linux/drivers/scsi/scsi_lib.c

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/*
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
* Copyright (C) 1999 Eric Youngdale
* Copyright (C) 2014 Christoph Hellwig
*
* SCSI queueing library.
* Initial versions: Eric Youngdale (eric@andante.org).
* Based upon conversations with large numbers
* of people at Linux Expo.
*/
#include <linux/bio.h>
#include <linux/bitops.h>
#include <linux/blkdev.h>
#include <linux/completion.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <linux/scatterlist.h>
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
#include <linux/blk-mq.h>
#include <linux/ratelimit.h>
#include <asm/unaligned.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_dh.h>
#include <trace/events/scsi.h>
#include "scsi_priv.h"
#include "scsi_logging.h"
static struct kmem_cache *scsi_sdb_cache;
static struct kmem_cache *scsi_sense_cache;
static struct kmem_cache *scsi_sense_isadma_cache;
static DEFINE_MUTEX(scsi_sense_cache_mutex);
static inline struct kmem_cache *
scsi_select_sense_cache(struct Scsi_Host *shost)
{
return shost->unchecked_isa_dma ?
scsi_sense_isadma_cache : scsi_sense_cache;
}
static void scsi_free_sense_buffer(struct Scsi_Host *shost,
unsigned char *sense_buffer)
{
kmem_cache_free(scsi_select_sense_cache(shost), sense_buffer);
}
static unsigned char *scsi_alloc_sense_buffer(struct Scsi_Host *shost,
gfp_t gfp_mask, int numa_node)
{
return kmem_cache_alloc_node(scsi_select_sense_cache(shost), gfp_mask,
numa_node);
}
int scsi_init_sense_cache(struct Scsi_Host *shost)
{
struct kmem_cache *cache;
int ret = 0;
cache = scsi_select_sense_cache(shost);
if (cache)
return 0;
mutex_lock(&scsi_sense_cache_mutex);
if (shost->unchecked_isa_dma) {
scsi_sense_isadma_cache =
kmem_cache_create("scsi_sense_cache(DMA)",
SCSI_SENSE_BUFFERSIZE, 0,
SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA, NULL);
if (!scsi_sense_isadma_cache)
ret = -ENOMEM;
} else {
scsi_sense_cache =
kmem_cache_create("scsi_sense_cache",
SCSI_SENSE_BUFFERSIZE, 0, SLAB_HWCACHE_ALIGN, NULL);
if (!scsi_sense_cache)
ret = -ENOMEM;
}
mutex_unlock(&scsi_sense_cache_mutex);
return ret;
}
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
/*
* When to reinvoke queueing after a resource shortage. It's 3 msecs to
* not change behaviour from the previous unplug mechanism, experimentation
* may prove this needs changing.
*/
#define SCSI_QUEUE_DELAY 3
static void
scsi_set_blocked(struct scsi_cmnd *cmd, int reason)
{
struct Scsi_Host *host = cmd->device->host;
struct scsi_device *device = cmd->device;
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
struct scsi_target *starget = scsi_target(device);
/*
* Set the appropriate busy bit for the device/host.
*
* If the host/device isn't busy, assume that something actually
* completed, and that we should be able to queue a command now.
*
* Note that the prior mid-layer assumption that any host could
* always queue at least one command is now broken. The mid-layer
* will implement a user specifiable stall (see
* scsi_host.max_host_blocked and scsi_device.max_device_blocked)
* if a command is requeued with no other commands outstanding
* either for the device or for the host.
*/
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
switch (reason) {
case SCSI_MLQUEUE_HOST_BUSY:
atomic_set(&host->host_blocked, host->max_host_blocked);
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
break;
case SCSI_MLQUEUE_DEVICE_BUSY:
[SCSI] scsi_lib: pause between error retries During cable pull tests on our 16G FC adapter, we are seeing errors, typically reads to close targets, which fail due to CRC or framing errors caused by the cable being pull (return status DID_ERROR). The adapter detects the error on one of the first frames received, marks the FC exchange as dead (further frames go to bit bucket) and signals the host of the error. This action is so quick, and coupled with fast host CPUs, creates a scenario in which the midlayer sees the failure and retries the io almost immediately. We've seen link traces with the retry on the link while the original i/o is still being processed by the target. We're also seeing the time window for the "link to pull-apart" and the physical interface to report disconnected to be in the few millisecond range. Which means, we're encountering scenarios where the full retry count is exhausted (all with error) by the midlayer before the link disconnect state is detected. We looked at 8G FC behavior and occasionally see the same behavior, but as the link was slower, it rarely could exhaust all retries before the link reported disconnect. What is needed is a slight delay between io retries due to DID_ERROR to cover this error. It is inappropriate to put this delay in the driver, as the error is indistinguishable from other link-related errors, nor does the driver track whether the io is a retry or not. This is also easier than tracking between-io-error bursts that are seen in this scenario. The patch below updates the retry path so that it inserts a delay as if the target was busy. The busy delay is on the order of 6ms. This delay is sufficient to ensure the link down condition is reported before the retry count is exhausted (at most 1 retry is seen). Signed-off-by: Alex Iannicelli <alex.iannicelli@emulex.com> Signed-off-by: James Smart <james.smart@emulex.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2011-07-06 16:45:17 +00:00
case SCSI_MLQUEUE_EH_RETRY:
atomic_set(&device->device_blocked,
device->max_device_blocked);
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
break;
case SCSI_MLQUEUE_TARGET_BUSY:
atomic_set(&starget->target_blocked,
starget->max_target_blocked);
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
break;
}
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd)
{
struct scsi_device *sdev = cmd->device;
blk_mq_requeue_request(cmd->request, true);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
put_device(&sdev->sdev_gendev);
}
/**
* __scsi_queue_insert - private queue insertion
* @cmd: The SCSI command being requeued
* @reason: The reason for the requeue
* @unbusy: Whether the queue should be unbusied
*
* This is a private queue insertion. The public interface
* scsi_queue_insert() always assumes the queue should be unbusied
* because it's always called before the completion. This function is
* for a requeue after completion, which should only occur in this
* file.
*/
static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
{
struct scsi_device *device = cmd->device;
struct request_queue *q = device->request_queue;
unsigned long flags;
SCSI_LOG_MLQUEUE(1, scmd_printk(KERN_INFO, cmd,
"Inserting command %p into mlqueue\n", cmd));
scsi_set_blocked(cmd, reason);
/*
* Decrement the counters, since these commands are no longer
* active on the host/device.
*/
if (unbusy)
scsi_device_unbusy(device);
/*
* Requeue this command. It will go before all other commands
* that are already in the queue. Schedule requeue work under
* lock such that the kblockd_schedule_work() call happens
* before blk_cleanup_queue() finishes.
*/
cmd->result = 0;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (q->mq_ops) {
scsi_mq_requeue_cmd(cmd);
return;
}
spin_lock_irqsave(q->queue_lock, flags);
blk_requeue_request(q, cmd->request);
kblockd_schedule_work(&device->requeue_work);
spin_unlock_irqrestore(q->queue_lock, flags);
}
/*
* Function: scsi_queue_insert()
*
* Purpose: Insert a command in the midlevel queue.
*
* Arguments: cmd - command that we are adding to queue.
* reason - why we are inserting command to queue.
*
* Lock status: Assumed that lock is not held upon entry.
*
* Returns: Nothing.
*
* Notes: We do this for one of two cases. Either the host is busy
* and it cannot accept any more commands for the time being,
* or the device returned QUEUE_FULL and can accept no more
* commands.
* Notes: This could be called either from an interrupt context or a
* normal process context.
*/
void scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
{
__scsi_queue_insert(cmd, reason, 1);
}
static int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
int data_direction, void *buffer, unsigned bufflen,
unsigned char *sense, int timeout, int retries, u64 flags,
req_flags_t rq_flags, int *resid)
{
struct request *req;
struct scsi_request *rq;
int ret = DRIVER_ERROR << 24;
req = blk_get_request(sdev->request_queue,
data_direction == DMA_TO_DEVICE ?
REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, __GFP_RECLAIM);
if (IS_ERR(req))
return ret;
rq = scsi_req(req);
scsi_req_init(req);
if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
buffer, bufflen, __GFP_RECLAIM))
goto out;
rq->cmd_len = COMMAND_SIZE(cmd[0]);
memcpy(rq->cmd, cmd, rq->cmd_len);
req->retries = retries;
req->timeout = timeout;
req->cmd_flags |= flags;
req->rq_flags |= rq_flags | RQF_QUIET | RQF_PREEMPT;
/*
* head injection *required* here otherwise quiesce won't work
*/
blk_execute_rq(req->q, NULL, req, 1);
/*
* Some devices (USB mass-storage in particular) may transfer
* garbage data together with a residue indicating that the data
* is invalid. Prevent the garbage from being misinterpreted
* and prevent security leaks by zeroing out the excess data.
*/
if (unlikely(rq->resid_len > 0 && rq->resid_len <= bufflen))
memset(buffer + (bufflen - rq->resid_len), 0, rq->resid_len);
if (resid)
*resid = rq->resid_len;
if (sense && rq->sense_len)
memcpy(sense, rq->sense, SCSI_SENSE_BUFFERSIZE);
ret = req->errors;
out:
blk_put_request(req);
return ret;
}
/**
* scsi_execute - insert request and wait for the result
* @sdev: scsi device
* @cmd: scsi command
* @data_direction: data direction
* @buffer: data buffer
* @bufflen: len of buffer
* @sense: optional sense buffer
* @timeout: request timeout in seconds
* @retries: number of times to retry request
* @flags: or into request flags;
* @resid: optional residual length
*
* returns the req->errors value which is the scsi_cmnd result
* field.
*/
int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
int data_direction, void *buffer, unsigned bufflen,
unsigned char *sense, int timeout, int retries, u64 flags,
int *resid)
{
return __scsi_execute(sdev, cmd, data_direction, buffer, bufflen, sense,
timeout, retries, flags, 0, resid);
}
EXPORT_SYMBOL(scsi_execute);
int scsi_execute_req_flags(struct scsi_device *sdev, const unsigned char *cmd,
int data_direction, void *buffer, unsigned bufflen,
struct scsi_sense_hdr *sshdr, int timeout, int retries,
int *resid, u64 flags, req_flags_t rq_flags)
{
char *sense = NULL;
int result;
if (sshdr) {
sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
if (!sense)
return DRIVER_ERROR << 24;
}
result = __scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
sense, timeout, retries, flags, rq_flags, resid);
if (sshdr)
scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
kfree(sense);
return result;
}
EXPORT_SYMBOL(scsi_execute_req_flags);
/*
* Function: scsi_init_cmd_errh()
*
* Purpose: Initialize cmd fields related to error handling.
*
* Arguments: cmd - command that is ready to be queued.
*
* Notes: This function has the job of initializing a number of
* fields related to error handling. Typically this will
* be called once for each command, as required.
*/
static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
{
cmd->serial_number = 0;
scsi_set_resid(cmd, 0);
memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
if (cmd->cmd_len == 0)
cmd->cmd_len = scsi_command_size(cmd->cmnd);
}
void scsi_device_unbusy(struct scsi_device *sdev)
{
struct Scsi_Host *shost = sdev->host;
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
struct scsi_target *starget = scsi_target(sdev);
unsigned long flags;
atomic_dec(&shost->host_busy);
if (starget->can_queue > 0)
atomic_dec(&starget->target_busy);
if (unlikely(scsi_host_in_recovery(shost) &&
(shost->host_failed || shost->host_eh_scheduled))) {
spin_lock_irqsave(shost->host_lock, flags);
scsi_eh_wakeup(shost);
spin_unlock_irqrestore(shost->host_lock, flags);
}
atomic_dec(&sdev->device_busy);
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
static void scsi_kick_queue(struct request_queue *q)
{
if (q->mq_ops)
blk_mq_start_hw_queues(q);
else
blk_run_queue(q);
}
/*
* Called for single_lun devices on IO completion. Clear starget_sdev_user,
* and call blk_run_queue for all the scsi_devices on the target -
* including current_sdev first.
*
* Called with *no* scsi locks held.
*/
static void scsi_single_lun_run(struct scsi_device *current_sdev)
{
struct Scsi_Host *shost = current_sdev->host;
struct scsi_device *sdev, *tmp;
struct scsi_target *starget = scsi_target(current_sdev);
unsigned long flags;
spin_lock_irqsave(shost->host_lock, flags);
starget->starget_sdev_user = NULL;
spin_unlock_irqrestore(shost->host_lock, flags);
/*
* Call blk_run_queue for all LUNs on the target, starting with
* current_sdev. We race with others (to set starget_sdev_user),
* but in most cases, we will be first. Ideally, each LU on the
* target would get some limited time or requests on the target.
*/
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
scsi_kick_queue(current_sdev->request_queue);
spin_lock_irqsave(shost->host_lock, flags);
if (starget->starget_sdev_user)
goto out;
list_for_each_entry_safe(sdev, tmp, &starget->devices,
same_target_siblings) {
if (sdev == current_sdev)
continue;
if (scsi_device_get(sdev))
continue;
spin_unlock_irqrestore(shost->host_lock, flags);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
scsi_kick_queue(sdev->request_queue);
spin_lock_irqsave(shost->host_lock, flags);
scsi_device_put(sdev);
}
out:
spin_unlock_irqrestore(shost->host_lock, flags);
}
static inline bool scsi_device_is_busy(struct scsi_device *sdev)
{
if (atomic_read(&sdev->device_busy) >= sdev->queue_depth)
return true;
if (atomic_read(&sdev->device_blocked) > 0)
return true;
return false;
}
static inline bool scsi_target_is_busy(struct scsi_target *starget)
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
{
if (starget->can_queue > 0) {
if (atomic_read(&starget->target_busy) >= starget->can_queue)
return true;
if (atomic_read(&starget->target_blocked) > 0)
return true;
}
return false;
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
}
static inline bool scsi_host_is_busy(struct Scsi_Host *shost)
{
if (shost->can_queue > 0 &&
atomic_read(&shost->host_busy) >= shost->can_queue)
return true;
if (atomic_read(&shost->host_blocked) > 0)
return true;
if (shost->host_self_blocked)
return true;
return false;
}
static void scsi_starved_list_run(struct Scsi_Host *shost)
{
LIST_HEAD(starved_list);
struct scsi_device *sdev;
unsigned long flags;
spin_lock_irqsave(shost->host_lock, flags);
list_splice_init(&shost->starved_list, &starved_list);
while (!list_empty(&starved_list)) {
struct request_queue *slq;
/*
* As long as shost is accepting commands and we have
* starved queues, call blk_run_queue. scsi_request_fn
* drops the queue_lock and can add us back to the
* starved_list.
*
* host_lock protects the starved_list and starved_entry.
* scsi_request_fn must get the host_lock before checking
* or modifying starved_list or starved_entry.
*/
if (scsi_host_is_busy(shost))
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
break;
sdev = list_entry(starved_list.next,
struct scsi_device, starved_entry);
list_del_init(&sdev->starved_entry);
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
if (scsi_target_is_busy(scsi_target(sdev))) {
list_move_tail(&sdev->starved_entry,
&shost->starved_list);
continue;
}
/*
* Once we drop the host lock, a racing scsi_remove_device()
* call may remove the sdev from the starved list and destroy
* it and the queue. Mitigate by taking a reference to the
* queue and never touching the sdev again after we drop the
* host lock. Note: if __scsi_remove_device() invokes
* blk_cleanup_queue() before the queue is run from this
* function then blk_run_queue() will return immediately since
* blk_cleanup_queue() marks the queue with QUEUE_FLAG_DYING.
*/
slq = sdev->request_queue;
if (!blk_get_queue(slq))
continue;
spin_unlock_irqrestore(shost->host_lock, flags);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
scsi_kick_queue(slq);
blk_put_queue(slq);
spin_lock_irqsave(shost->host_lock, flags);
}
/* put any unprocessed entries back */
list_splice(&starved_list, &shost->starved_list);
spin_unlock_irqrestore(shost->host_lock, flags);
}
/*
* Function: scsi_run_queue()
*
* Purpose: Select a proper request queue to serve next
*
* Arguments: q - last request's queue
*
* Returns: Nothing
*
* Notes: The previous command was completely finished, start
* a new one if possible.
*/
static void scsi_run_queue(struct request_queue *q)
{
struct scsi_device *sdev = q->queuedata;
if (scsi_target(sdev)->single_lun)
scsi_single_lun_run(sdev);
if (!list_empty(&sdev->host->starved_list))
scsi_starved_list_run(sdev->host);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (q->mq_ops)
blk_mq_start_stopped_hw_queues(q, false);
else
blk_run_queue(q);
}
void scsi_requeue_run_queue(struct work_struct *work)
{
struct scsi_device *sdev;
struct request_queue *q;
sdev = container_of(work, struct scsi_device, requeue_work);
q = sdev->request_queue;
scsi_run_queue(q);
}
/*
* Function: scsi_requeue_command()
*
* Purpose: Handle post-processing of completed commands.
*
* Arguments: q - queue to operate on
* cmd - command that may need to be requeued.
*
* Returns: Nothing
*
* Notes: After command completion, there may be blocks left
* over which weren't finished by the previous command
* this can be for a number of reasons - the main one is
* I/O errors in the middle of the request, in which case
* we need to request the blocks that come after the bad
* sector.
* Notes: Upon return, cmd is a stale pointer.
*/
static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
{
struct scsi_device *sdev = cmd->device;
struct request *req = cmd->request;
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
blk_unprep_request(req);
req->special = NULL;
scsi_put_command(cmd);
blk_requeue_request(q, req);
spin_unlock_irqrestore(q->queue_lock, flags);
scsi_run_queue(q);
put_device(&sdev->sdev_gendev);
}
void scsi_run_host_queues(struct Scsi_Host *shost)
{
struct scsi_device *sdev;
shost_for_each_device(sdev, shost)
scsi_run_queue(sdev->request_queue);
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
{
if (!blk_rq_is_passthrough(cmd->request)) {
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
if (drv->uninit_command)
drv->uninit_command(cmd);
}
}
static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
{
struct scsi_data_buffer *sdb;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (cmd->sdb.table.nents)
sg_free_table_chained(&cmd->sdb.table, true);
if (cmd->request->next_rq) {
sdb = cmd->request->next_rq->special;
if (sdb)
sg_free_table_chained(&sdb->table, true);
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (scsi_prot_sg_count(cmd))
sg_free_table_chained(&cmd->prot_sdb->table, true);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
}
static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
{
struct scsi_device *sdev = cmd->device;
struct Scsi_Host *shost = sdev->host;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
unsigned long flags;
scsi_mq_free_sgtables(cmd);
scsi_uninit_cmd(cmd);
if (shost->use_cmd_list) {
BUG_ON(list_empty(&cmd->list));
spin_lock_irqsave(&sdev->list_lock, flags);
list_del_init(&cmd->list);
spin_unlock_irqrestore(&sdev->list_lock, flags);
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
}
/*
* Function: scsi_release_buffers()
*
* Purpose: Free resources allocate for a scsi_command.
*
* Arguments: cmd - command that we are bailing.
*
* Lock status: Assumed that no lock is held upon entry.
*
* Returns: Nothing
*
* Notes: In the event that an upper level driver rejects a
* command, we must release resources allocated during
* the __init_io() function. Primarily this would involve
* the scatter-gather table.
*/
static void scsi_release_buffers(struct scsi_cmnd *cmd)
{
if (cmd->sdb.table.nents)
sg_free_table_chained(&cmd->sdb.table, false);
memset(&cmd->sdb, 0, sizeof(cmd->sdb));
if (scsi_prot_sg_count(cmd))
sg_free_table_chained(&cmd->prot_sdb->table, false);
}
static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd)
{
struct scsi_data_buffer *bidi_sdb = cmd->request->next_rq->special;
sg_free_table_chained(&bidi_sdb->table, false);
kmem_cache_free(scsi_sdb_cache, bidi_sdb);
cmd->request->next_rq->special = NULL;
}
static bool scsi_end_request(struct request *req, int error,
unsigned int bytes, unsigned int bidi_bytes)
{
struct scsi_cmnd *cmd = req->special;
struct scsi_device *sdev = cmd->device;
struct request_queue *q = sdev->request_queue;
if (blk_update_request(req, error, bytes))
return true;
/* Bidi request must be completed as a whole */
if (unlikely(bidi_bytes) &&
blk_update_request(req->next_rq, error, bidi_bytes))
return true;
if (blk_queue_add_random(q))
add_disk_randomness(req->rq_disk);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (req->mq_ctx) {
/*
* In the MQ case the command gets freed by __blk_mq_end_request,
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
* so we have to do all cleanup that depends on it earlier.
*
* We also can't kick the queues from irq context, so we
* will have to defer it to a workqueue.
*/
scsi_mq_uninit_cmd(cmd);
__blk_mq_end_request(req, error);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (scsi_target(sdev)->single_lun ||
!list_empty(&sdev->host->starved_list))
kblockd_schedule_work(&sdev->requeue_work);
else
blk_mq_start_stopped_hw_queues(q, true);
} else {
unsigned long flags;
if (bidi_bytes)
scsi_release_bidi_buffers(cmd);
scsi_release_buffers(cmd);
scsi_put_command(cmd);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
spin_lock_irqsave(q->queue_lock, flags);
blk_finish_request(req, error);
spin_unlock_irqrestore(q->queue_lock, flags);
scsi_run_queue(q);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
}
put_device(&sdev->sdev_gendev);
return false;
}
/**
* __scsi_error_from_host_byte - translate SCSI error code into errno
* @cmd: SCSI command (unused)
* @result: scsi error code
*
* Translate SCSI error code into standard UNIX errno.
* Return values:
* -ENOLINK temporary transport failure
* -EREMOTEIO permanent target failure, do not retry
* -EBADE permanent nexus failure, retry on other path
* -ENOSPC No write space available
* -ENODATA Medium error
* -EIO unspecified I/O error
*/
static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
{
int error = 0;
switch(host_byte(result)) {
case DID_TRANSPORT_FAILFAST:
error = -ENOLINK;
break;
case DID_TARGET_FAILURE:
set_host_byte(cmd, DID_OK);
error = -EREMOTEIO;
break;
case DID_NEXUS_FAILURE:
set_host_byte(cmd, DID_OK);
error = -EBADE;
break;
case DID_ALLOC_FAILURE:
set_host_byte(cmd, DID_OK);
error = -ENOSPC;
break;
case DID_MEDIUM_ERROR:
set_host_byte(cmd, DID_OK);
error = -ENODATA;
break;
default:
error = -EIO;
break;
}
return error;
}
/*
* Function: scsi_io_completion()
*
* Purpose: Completion processing for block device I/O requests.
*
* Arguments: cmd - command that is finished.
*
* Lock status: Assumed that no lock is held upon entry.
*
* Returns: Nothing
*
* Notes: We will finish off the specified number of sectors. If we
* are done, the command block will be released and the queue
* function will be goosed. If we are not done then we have to
* figure out what to do next:
*
* a) We can call scsi_requeue_command(). The request
* will be unprepared and put back on the queue. Then
* a new command will be created for it. This should
* be used if we made forward progress, or if we want
* to switch from READ(10) to READ(6) for example.
*
* b) We can call __scsi_queue_insert(). The request will
* be put back on the queue and retried using the same
* command as before, possibly after a delay.
*
* c) We can call scsi_end_request() with -EIO to fail
* the remainder of the request.
*/
void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
{
int result = cmd->result;
struct request_queue *q = cmd->device->request_queue;
struct request *req = cmd->request;
int error = 0;
struct scsi_sense_hdr sshdr;
bool sense_valid = false;
int sense_deferred = 0, level = 0;
enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
ACTION_DELAYED_RETRY} action;
unsigned long wait_for = (cmd->allowed + 1) * req->timeout;
if (result) {
sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
if (sense_valid)
sense_deferred = scsi_sense_is_deferred(&sshdr);
}
if (blk_rq_is_passthrough(req)) {
if (result) {
if (sense_valid) {
/*
* SG_IO wants current and deferred errors
*/
scsi_req(req)->sense_len =
min(8 + cmd->sense_buffer[7],
SCSI_SENSE_BUFFERSIZE);
}
if (!sense_deferred)
error = __scsi_error_from_host_byte(cmd, result);
}
[SCSI] scsi_lib: fix scsi_io_completion's SG_IO error propagation The following v3.4-rc1 commit unmasked an existing bug in scsi_io_completion's SG_IO error handling: 47ac56d [SCSI] scsi_error: classify some ILLEGAL_REQUEST sense as a permanent TARGET_ERROR Given that certain ILLEGAL_REQUEST are now properly categorized as TARGET_ERROR the host_byte is being set (before host_byte wasn't ever set for these ILLEGAL_REQUEST). In scsi_io_completion, initialize req->errors with cmd->result _after_ the SG_IO block that calls __scsi_error_from_host_byte (which may modify the host_byte). Before this fix: cdb to send: 12 01 01 00 00 00 ioctl(3, SG_IO, {'S', SG_DXFER_NONE, cmd[6]=[12, 01, 01, 00, 00, 00], mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=20000, flags=0, status=02, masked_status=01, sb[19]=[70, 00, 05, 00, 00, 00, 00, 0b, 00, 00, 00, 00, 24, 00, 00, 00, 00, 00, 00], host_status=0x10, driver_status=0x8, resid=0, duration=0, info=0x1}) = 0 SCSI Status: Check Condition Sense Information: sense buffer empty After: cdb to send: 12 01 01 00 00 00 ioctl(3, SG_IO, {'S', SG_DXFER_NONE, cmd[6]=[12, 01, 01, 00, 00, 00], mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=20000, flags=0, status=02, masked_status=01, sb[19]=[70, 00, 05, 00, 00, 00, 00, 0b, 00, 00, 00, 00, 24, 00, 00, 00, 00, 00, 00], host_status=0, driver_status=0x8, resid=0, duration=0, info=0x1}) = 0 SCSI Status: Check Condition Sense Information: Fixed format, current; Sense key: Illegal Request Additional sense: Invalid field in cdb Raw sense data (in hex): 70 00 05 00 00 00 00 0b 00 00 00 00 24 00 00 00 00 00 00 Reported-by: Paolo Bonzini <pbonzini@redhat.com> Tested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Babu Moger <babu.moger@netapp.com> Cc: stable@vger.kernel.org # 3.4 Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2012-05-31 19:05:33 +00:00
/*
* __scsi_error_from_host_byte may have reset the host_byte
*/
req->errors = cmd->result;
scsi_req(req)->resid_len = scsi_get_resid(cmd);
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
if (scsi_bidi_cmnd(cmd)) {
/*
* Bidi commands Must be complete as a whole,
* both sides at once.
*/
scsi_req(req->next_rq)->resid_len = scsi_in(cmd)->resid;
if (scsi_end_request(req, 0, blk_rq_bytes(req),
blk_rq_bytes(req->next_rq)))
BUG();
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
return;
}
} else if (blk_rq_bytes(req) == 0 && result && !sense_deferred) {
/*
* Flush commands do not transfers any data, and thus cannot use
* good_bytes != blk_rq_bytes(req) as the signal for an error.
* This sets the error explicitly for the problem case.
*/
error = __scsi_error_from_host_byte(cmd, result);
}
/* no bidi support for !blk_rq_is_passthrough yet */
BUG_ON(blk_bidi_rq(req));
/*
* Next deal with any sectors which we were able to correctly
* handle.
*/
SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, cmd,
"%u sectors total, %d bytes done.\n",
blk_rq_sectors(req), good_bytes));
/*
* Recovered errors need reporting, but they're always treated as
* success, so fiddle the result code here. For passthrough requests
* we already took a copy of the original into rq->errors which
* is what gets returned to the user
*/
if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
/* if ATA PASS-THROUGH INFORMATION AVAILABLE skip
* print since caller wants ATA registers. Only occurs on
* SCSI ATA PASS_THROUGH commands when CK_COND=1
*/
if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
;
else if (!(req->rq_flags & RQF_QUIET))
scsi_print_sense(cmd);
result = 0;
/* for passthrough error may be set */
error = 0;
}
/*
* special case: failed zero length commands always need to
* drop down into the retry code. Otherwise, if we finished
* all bytes in the request we are done now.
*/
if (!(blk_rq_bytes(req) == 0 && error) &&
!scsi_end_request(req, error, good_bytes, 0))
return;
/*
* Kill remainder if no retrys.
*/
if (error && scsi_noretry_cmd(cmd)) {
if (scsi_end_request(req, error, blk_rq_bytes(req), 0))
BUG();
return;
}
/*
* If there had been no error, but we have leftover bytes in the
* requeues just queue the command up again.
*/
if (result == 0)
goto requeue;
error = __scsi_error_from_host_byte(cmd, result);
if (host_byte(result) == DID_RESET) {
/* Third party bus reset or reset for error recovery
* reasons. Just retry the command and see what
* happens.
*/
action = ACTION_RETRY;
} else if (sense_valid && !sense_deferred) {
switch (sshdr.sense_key) {
case UNIT_ATTENTION:
if (cmd->device->removable) {
/* Detected disc change. Set a bit
* and quietly refuse further access.
*/
cmd->device->changed = 1;
action = ACTION_FAIL;
} else {
/* Must have been a power glitch, or a
* bus reset. Could not have been a
* media change, so we just retry the
* command and see what happens.
*/
action = ACTION_RETRY;
}
break;
case ILLEGAL_REQUEST:
/* If we had an ILLEGAL REQUEST returned, then
* we may have performed an unsupported
* command. The only thing this should be
* would be a ten byte read where only a six
* byte read was supported. Also, on a system
* where READ CAPACITY failed, we may have
* read past the end of the disk.
*/
if ((cmd->device->use_10_for_rw &&
sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
(cmd->cmnd[0] == READ_10 ||
cmd->cmnd[0] == WRITE_10)) {
/* This will issue a new 6-byte command. */
cmd->device->use_10_for_rw = 0;
action = ACTION_REPREP;
} else if (sshdr.asc == 0x10) /* DIX */ {
action = ACTION_FAIL;
error = -EILSEQ;
/* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
} else if (sshdr.asc == 0x20 || sshdr.asc == 0x24) {
action = ACTION_FAIL;
error = -EREMOTEIO;
} else
action = ACTION_FAIL;
break;
case ABORTED_COMMAND:
action = ACTION_FAIL;
if (sshdr.asc == 0x10) /* DIF */
error = -EILSEQ;
break;
case NOT_READY:
/* If the device is in the process of becoming
* ready, or has a temporary blockage, retry.
*/
if (sshdr.asc == 0x04) {
switch (sshdr.ascq) {
case 0x01: /* becoming ready */
case 0x04: /* format in progress */
case 0x05: /* rebuild in progress */
case 0x06: /* recalculation in progress */
case 0x07: /* operation in progress */
case 0x08: /* Long write in progress */
case 0x09: /* self test in progress */
case 0x14: /* space allocation in progress */
action = ACTION_DELAYED_RETRY;
break;
default:
action = ACTION_FAIL;
break;
}
} else
action = ACTION_FAIL;
break;
case VOLUME_OVERFLOW:
/* See SSC3rXX or current. */
action = ACTION_FAIL;
break;
default:
action = ACTION_FAIL;
break;
}
} else
action = ACTION_FAIL;
if (action != ACTION_FAIL &&
time_before(cmd->jiffies_at_alloc + wait_for, jiffies))
action = ACTION_FAIL;
switch (action) {
case ACTION_FAIL:
/* Give up and fail the remainder of the request */
if (!(req->rq_flags & RQF_QUIET)) {
static DEFINE_RATELIMIT_STATE(_rs,
DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
if (unlikely(scsi_logging_level))
level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
SCSI_LOG_MLCOMPLETE_BITS);
/*
* if logging is enabled the failure will be printed
* in scsi_log_completion(), so avoid duplicate messages
*/
if (!level && __ratelimit(&_rs)) {
scsi_print_result(cmd, NULL, FAILED);
if (driver_byte(result) & DRIVER_SENSE)
scsi_print_sense(cmd);
scsi_print_command(cmd);
}
}
if (!scsi_end_request(req, error, blk_rq_err_bytes(req), 0))
return;
/*FALLTHRU*/
case ACTION_REPREP:
requeue:
/* Unprep the request and put it back at the head of the queue.
* A new command will be prepared and issued.
*/
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (q->mq_ops) {
cmd->request->rq_flags &= ~RQF_DONTPREP;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
scsi_mq_uninit_cmd(cmd);
scsi_mq_requeue_cmd(cmd);
} else {
scsi_release_buffers(cmd);
scsi_requeue_command(q, cmd);
}
break;
case ACTION_RETRY:
/* Retry the same command immediately */
__scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
break;
case ACTION_DELAYED_RETRY:
/* Retry the same command after a delay */
__scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
break;
}
}
static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb)
{
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
int count;
/*
* If sg table allocation fails, requeue request later.
*/
if (unlikely(sg_alloc_table_chained(&sdb->table,
blk_rq_nr_phys_segments(req), sdb->table.sgl)))
return BLKPREP_DEFER;
/*
* Next, walk the list, and fill in the addresses and sizes of
* each segment.
*/
count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
BUG_ON(count > sdb->table.nents);
sdb->table.nents = count;
sdb->length = blk_rq_payload_bytes(req);
return BLKPREP_OK;
}
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
/*
* Function: scsi_init_io()
*
* Purpose: SCSI I/O initialize function.
*
* Arguments: cmd - Command descriptor we wish to initialize
*
* Returns: 0 on success
* BLKPREP_DEFER if the failure is retryable
* BLKPREP_KILL if the failure is fatal
*/
int scsi_init_io(struct scsi_cmnd *cmd)
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
{
struct scsi_device *sdev = cmd->device;
struct request *rq = cmd->request;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
bool is_mq = (rq->mq_ctx != NULL);
int error;
BUG_ON(!blk_rq_nr_phys_segments(rq));
error = scsi_init_sgtable(rq, &cmd->sdb);
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
if (error)
goto err_exit;
if (blk_bidi_rq(rq)) {
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (!rq->q->mq_ops) {
struct scsi_data_buffer *bidi_sdb =
kmem_cache_zalloc(scsi_sdb_cache, GFP_ATOMIC);
if (!bidi_sdb) {
error = BLKPREP_DEFER;
goto err_exit;
}
rq->next_rq->special = bidi_sdb;
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
}
error = scsi_init_sgtable(rq->next_rq, rq->next_rq->special);
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
if (error)
goto err_exit;
}
if (blk_integrity_rq(rq)) {
struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
int ivecs, count;
if (prot_sdb == NULL) {
/*
* This can happen if someone (e.g. multipath)
* queues a command to a device on an adapter
* that does not support DIX.
*/
WARN_ON_ONCE(1);
error = BLKPREP_KILL;
goto err_exit;
}
ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
if (sg_alloc_table_chained(&prot_sdb->table, ivecs,
prot_sdb->table.sgl)) {
error = BLKPREP_DEFER;
goto err_exit;
}
count = blk_rq_map_integrity_sg(rq->q, rq->bio,
prot_sdb->table.sgl);
BUG_ON(unlikely(count > ivecs));
BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q)));
cmd->prot_sdb = prot_sdb;
cmd->prot_sdb->table.nents = count;
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
return BLKPREP_OK;
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
err_exit:
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (is_mq) {
scsi_mq_free_sgtables(cmd);
} else {
scsi_release_buffers(cmd);
cmd->request->special = NULL;
scsi_put_command(cmd);
put_device(&sdev->sdev_gendev);
}
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
return error;
}
EXPORT_SYMBOL(scsi_init_io);
void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
{
void *buf = cmd->sense_buffer;
void *prot = cmd->prot_sdb;
unsigned long flags;
/* zero out the cmd, except for the embedded scsi_request */
memset((char *)cmd + sizeof(cmd->req), 0,
sizeof(*cmd) - sizeof(cmd->req));
cmd->device = dev;
cmd->sense_buffer = buf;
cmd->prot_sdb = prot;
INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
cmd->jiffies_at_alloc = jiffies;
[SCSI] Let scsi_cmnd->cmnd use request->cmd buffer - struct scsi_cmnd had a 16 bytes command buffer of its own. This is an unnecessary duplication and copy of request's cmd. It is probably left overs from the time that scsi_cmnd could function without a request attached. So clean that up. - Once above is done, few places, apart from scsi-ml, needed adjustments due to changing the data type of scsi_cmnd->cmnd. - Lots of drivers still use MAX_COMMAND_SIZE. So I have left that #define but equate it to BLK_MAX_CDB. The way I see it and is reflected in the patch below is. MAX_COMMAND_SIZE - means: The longest fixed-length (*) SCSI CDB as per the SCSI standard and is not related to the implementation. BLK_MAX_CDB. - The allocated space at the request level - I have audit all ISA drivers and made sure none use ->cmnd in a DMA Operation. Same audit was done by Andi Kleen. (*)fixed-length here means commands that their size can be determined by their opcode and the CDB does not carry a length specifier, (unlike the VARIABLE_LENGTH_CMD(0x7f) command). This is actually not exactly true and the SCSI standard also defines extended commands and vendor specific commands that can be bigger than 16 bytes. The kernel will support these using the same infrastructure used for VARLEN CDB's. So in effect MAX_COMMAND_SIZE means the maximum size command scsi-ml supports without specifying a cmd_len by ULD's Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-04-30 08:19:47 +00:00
spin_lock_irqsave(&dev->list_lock, flags);
list_add_tail(&cmd->list, &dev->cmd_list);
spin_unlock_irqrestore(&dev->list_lock, flags);
}
static int scsi_setup_scsi_cmnd(struct scsi_device *sdev, struct request *req)
{
struct scsi_cmnd *cmd = req->special;
/*
* Passthrough requests may transfer data, in which case they must
* a bio attached to them. Or they might contain a SCSI command
* that does not transfer data, in which case they may optionally
* submit a request without an attached bio.
*/
if (req->bio) {
int ret = scsi_init_io(cmd);
if (unlikely(ret))
return ret;
} else {
BUG_ON(blk_rq_bytes(req));
memset(&cmd->sdb, 0, sizeof(cmd->sdb));
}
cmd->cmd_len = scsi_req(req)->cmd_len;
cmd->cmnd = scsi_req(req)->cmd;
cmd->transfersize = blk_rq_bytes(req);
cmd->allowed = req->retries;
return BLKPREP_OK;
}
/*
* Setup a normal block command. These are simple request from filesystems
* that still need to be translated to SCSI CDBs from the ULD.
*/
static int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
{
struct scsi_cmnd *cmd = req->special;
if (unlikely(sdev->handler && sdev->handler->prep_fn)) {
int ret = sdev->handler->prep_fn(sdev, req);
if (ret != BLKPREP_OK)
return ret;
}
cmd->cmnd = scsi_req(req)->cmd = scsi_req(req)->__cmd;
[SCSI] Let scsi_cmnd->cmnd use request->cmd buffer - struct scsi_cmnd had a 16 bytes command buffer of its own. This is an unnecessary duplication and copy of request's cmd. It is probably left overs from the time that scsi_cmnd could function without a request attached. So clean that up. - Once above is done, few places, apart from scsi-ml, needed adjustments due to changing the data type of scsi_cmnd->cmnd. - Lots of drivers still use MAX_COMMAND_SIZE. So I have left that #define but equate it to BLK_MAX_CDB. The way I see it and is reflected in the patch below is. MAX_COMMAND_SIZE - means: The longest fixed-length (*) SCSI CDB as per the SCSI standard and is not related to the implementation. BLK_MAX_CDB. - The allocated space at the request level - I have audit all ISA drivers and made sure none use ->cmnd in a DMA Operation. Same audit was done by Andi Kleen. (*)fixed-length here means commands that their size can be determined by their opcode and the CDB does not carry a length specifier, (unlike the VARIABLE_LENGTH_CMD(0x7f) command). This is actually not exactly true and the SCSI standard also defines extended commands and vendor specific commands that can be bigger than 16 bytes. The kernel will support these using the same infrastructure used for VARLEN CDB's. So in effect MAX_COMMAND_SIZE means the maximum size command scsi-ml supports without specifying a cmd_len by ULD's Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-04-30 08:19:47 +00:00
memset(cmd->cmnd, 0, BLK_MAX_CDB);
return scsi_cmd_to_driver(cmd)->init_command(cmd);
}
static int scsi_setup_cmnd(struct scsi_device *sdev, struct request *req)
{
struct scsi_cmnd *cmd = req->special;
if (!blk_rq_bytes(req))
cmd->sc_data_direction = DMA_NONE;
else if (rq_data_dir(req) == WRITE)
cmd->sc_data_direction = DMA_TO_DEVICE;
else
cmd->sc_data_direction = DMA_FROM_DEVICE;
if (blk_rq_is_scsi(req))
return scsi_setup_scsi_cmnd(sdev, req);
else
return scsi_setup_fs_cmnd(sdev, req);
}
static int
scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
{
int ret = BLKPREP_OK;
/*
* If the device is not in running state we will reject some
* or all commands.
*/
if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
switch (sdev->sdev_state) {
case SDEV_OFFLINE:
case SDEV_TRANSPORT_OFFLINE:
/*
* If the device is offline we refuse to process any
* commands. The device must be brought online
* before trying any recovery commands.
*/
sdev_printk(KERN_ERR, sdev,
"rejecting I/O to offline device\n");
ret = BLKPREP_KILL;
break;
case SDEV_DEL:
/*
* If the device is fully deleted, we refuse to
* process any commands as well.
*/
sdev_printk(KERN_ERR, sdev,
"rejecting I/O to dead device\n");
ret = BLKPREP_KILL;
break;
case SDEV_BLOCK:
case SDEV_CREATED_BLOCK:
Defer processing of REQ_PREEMPT requests for blocked devices SCSI transport drivers and SCSI LLDs block a SCSI device if the transport layer is not operational. This means that in this state no requests should be processed, even if the REQ_PREEMPT flag has been set. This patch avoids that a rescan shortly after a cable pull sporadically triggers the following kernel oops: BUG: unable to handle kernel paging request at ffffc9001a6bc084 IP: [<ffffffffa04e08f2>] mlx4_ib_post_send+0xd2/0xb30 [mlx4_ib] Process rescan-scsi-bus (pid: 9241, threadinfo ffff88053484a000, task ffff880534aae100) Call Trace: [<ffffffffa0718135>] srp_post_send+0x65/0x70 [ib_srp] [<ffffffffa071b9df>] srp_queuecommand+0x1cf/0x3e0 [ib_srp] [<ffffffffa0001ff1>] scsi_dispatch_cmd+0x101/0x280 [scsi_mod] [<ffffffffa0009ad1>] scsi_request_fn+0x411/0x4d0 [scsi_mod] [<ffffffff81223b37>] __blk_run_queue+0x27/0x30 [<ffffffff8122a8d2>] blk_execute_rq_nowait+0x82/0x110 [<ffffffff8122a9c2>] blk_execute_rq+0x62/0xf0 [<ffffffffa000b0e8>] scsi_execute+0xe8/0x190 [scsi_mod] [<ffffffffa000b2f3>] scsi_execute_req+0xa3/0x130 [scsi_mod] [<ffffffffa000c1aa>] scsi_probe_lun+0x17a/0x450 [scsi_mod] [<ffffffffa000ce86>] scsi_probe_and_add_lun+0x156/0x480 [scsi_mod] [<ffffffffa000dc2f>] __scsi_scan_target+0xdf/0x1f0 [scsi_mod] [<ffffffffa000dfa3>] scsi_scan_host_selected+0x183/0x1c0 [scsi_mod] [<ffffffffa000edfb>] scsi_scan+0xdb/0xe0 [scsi_mod] [<ffffffffa000ee13>] store_scan+0x13/0x20 [scsi_mod] [<ffffffff811c8d9b>] sysfs_write_file+0xcb/0x160 [<ffffffff811589de>] vfs_write+0xce/0x140 [<ffffffff81158b53>] sys_write+0x53/0xa0 [<ffffffff81464592>] system_call_fastpath+0x16/0x1b [<00007f611c9d9300>] 0x7f611c9d92ff Reported-by: Max Gurtuvoy <maxg@mellanox.com> Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Mike Christie <michaelc@cs.wisc.edu> Cc: <stable@vger.kernel.org> Signed-off-by: James Bottomley <JBottomley@Odin.com>
2015-03-04 09:31:47 +00:00
ret = BLKPREP_DEFER;
break;
case SDEV_QUIESCE:
/*
* If the devices is blocked we defer normal commands.
*/
if (!(req->rq_flags & RQF_PREEMPT))
ret = BLKPREP_DEFER;
break;
default:
/*
* For any other not fully online state we only allow
* special commands. In particular any user initiated
* command is not allowed.
*/
if (!(req->rq_flags & RQF_PREEMPT))
ret = BLKPREP_KILL;
break;
}
}
return ret;
}
static int
scsi_prep_return(struct request_queue *q, struct request *req, int ret)
{
struct scsi_device *sdev = q->queuedata;
switch (ret) {
case BLKPREP_KILL:
case BLKPREP_INVALID:
req->errors = DID_NO_CONNECT << 16;
/* release the command and kill it */
if (req->special) {
struct scsi_cmnd *cmd = req->special;
scsi_release_buffers(cmd);
scsi_put_command(cmd);
put_device(&sdev->sdev_gendev);
req->special = NULL;
}
break;
case BLKPREP_DEFER:
/*
block: implement and enforce request peek/start/fetch Till now block layer allowed two separate modes of request execution. A request is always acquired from the request queue via elv_next_request(). After that, drivers are free to either dequeue it or process it without dequeueing. Dequeue allows elv_next_request() to return the next request so that multiple requests can be in flight. Executing requests without dequeueing has its merits mostly in allowing drivers for simpler devices which can't do sg to deal with segments only without considering request boundary. However, the benefit this brings is dubious and declining while the cost of the API ambiguity is increasing. Segment based drivers are usually for very old or limited devices and as converting to dequeueing model isn't difficult, it doesn't justify the API overhead it puts on block layer and its more modern users. Previous patches converted all block low level drivers to dequeueing model. This patch completes the API transition by... * renaming elv_next_request() to blk_peek_request() * renaming blkdev_dequeue_request() to blk_start_request() * adding blk_fetch_request() which is combination of peek and start * disallowing completion of queued (not started) requests * applying new API to all LLDs Renamings are for consistency and to break out of tree code so that it's apparent that out of tree drivers need updating. [ Impact: block request issue API cleanup, no functional change ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Mike Miller <mike.miller@hp.com> Cc: unsik Kim <donari75@gmail.com> Cc: Paul Clements <paul.clements@steeleye.com> Cc: Tim Waugh <tim@cyberelk.net> Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Cc: David S. Miller <davem@davemloft.net> Cc: Laurent Vivier <Laurent@lvivier.info> Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: Adrian McMenamin <adrian@mcmen.demon.co.uk> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Alex Dubov <oakad@yahoo.com> Cc: Pierre Ossman <drzeus@drzeus.cx> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Markus Lidel <Markus.Lidel@shadowconnect.com> Cc: Stefan Weinhuber <wein@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-08 02:54:16 +00:00
* If we defer, the blk_peek_request() returns NULL, but the
* queue must be restarted, so we schedule a callback to happen
* shortly.
*/
if (atomic_read(&sdev->device_busy) == 0)
blk_delay_queue(q, SCSI_QUEUE_DELAY);
break;
default:
req->rq_flags |= RQF_DONTPREP;
}
return ret;
}
static int scsi_prep_fn(struct request_queue *q, struct request *req)
{
struct scsi_device *sdev = q->queuedata;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
int ret;
ret = scsi_prep_state_check(sdev, req);
if (ret != BLKPREP_OK)
goto out;
if (!req->special) {
/* Bail if we can't get a reference to the device */
if (unlikely(!get_device(&sdev->sdev_gendev))) {
ret = BLKPREP_DEFER;
goto out;
}
scsi_init_command(sdev, cmd);
req->special = cmd;
}
cmd->tag = req->tag;
cmd->request = req;
cmd->prot_op = SCSI_PROT_NORMAL;
ret = scsi_setup_cmnd(sdev, req);
out:
return scsi_prep_return(q, req, ret);
}
static void scsi_unprep_fn(struct request_queue *q, struct request *req)
{
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
scsi_uninit_cmd(req->special);
}
/*
* scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
* return 0.
*
* Called with the queue_lock held.
*/
static inline int scsi_dev_queue_ready(struct request_queue *q,
struct scsi_device *sdev)
{
unsigned int busy;
busy = atomic_inc_return(&sdev->device_busy) - 1;
if (atomic_read(&sdev->device_blocked)) {
if (busy)
goto out_dec;
/*
* unblock after device_blocked iterates to zero
*/
if (atomic_dec_return(&sdev->device_blocked) > 0) {
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
/*
* For the MQ case we take care of this in the caller.
*/
if (!q->mq_ops)
blk_delay_queue(q, SCSI_QUEUE_DELAY);
goto out_dec;
}
SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev,
"unblocking device at zero depth\n"));
}
if (busy >= sdev->queue_depth)
goto out_dec;
return 1;
out_dec:
atomic_dec(&sdev->device_busy);
return 0;
}
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
/*
* scsi_target_queue_ready: checks if there we can send commands to target
* @sdev: scsi device on starget to check.
*/
static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
struct scsi_device *sdev)
{
struct scsi_target *starget = scsi_target(sdev);
unsigned int busy;
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
if (starget->single_lun) {
spin_lock_irq(shost->host_lock);
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
if (starget->starget_sdev_user &&
starget->starget_sdev_user != sdev) {
spin_unlock_irq(shost->host_lock);
return 0;
}
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
starget->starget_sdev_user = sdev;
spin_unlock_irq(shost->host_lock);
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
}
if (starget->can_queue <= 0)
return 1;
busy = atomic_inc_return(&starget->target_busy) - 1;
if (atomic_read(&starget->target_blocked) > 0) {
if (busy)
goto starved;
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
/*
* unblock after target_blocked iterates to zero
*/
if (atomic_dec_return(&starget->target_blocked) > 0)
goto out_dec;
SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
"unblocking target at zero depth\n"));
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
}
if (busy >= starget->can_queue)
goto starved;
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
return 1;
starved:
spin_lock_irq(shost->host_lock);
list_move_tail(&sdev->starved_entry, &shost->starved_list);
spin_unlock_irq(shost->host_lock);
out_dec:
if (starget->can_queue > 0)
atomic_dec(&starget->target_busy);
return 0;
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
}
/*
* scsi_host_queue_ready: if we can send requests to shost, return 1 else
* return 0. We must end up running the queue again whenever 0 is
* returned, else IO can hang.
*/
static inline int scsi_host_queue_ready(struct request_queue *q,
struct Scsi_Host *shost,
struct scsi_device *sdev)
{
unsigned int busy;
if (scsi_host_in_recovery(shost))
return 0;
busy = atomic_inc_return(&shost->host_busy) - 1;
if (atomic_read(&shost->host_blocked) > 0) {
if (busy)
goto starved;
/*
* unblock after host_blocked iterates to zero
*/
if (atomic_dec_return(&shost->host_blocked) > 0)
goto out_dec;
SCSI_LOG_MLQUEUE(3,
shost_printk(KERN_INFO, shost,
"unblocking host at zero depth\n"));
}
if (shost->can_queue > 0 && busy >= shost->can_queue)
goto starved;
if (shost->host_self_blocked)
goto starved;
/* We're OK to process the command, so we can't be starved */
if (!list_empty(&sdev->starved_entry)) {
spin_lock_irq(shost->host_lock);
if (!list_empty(&sdev->starved_entry))
list_del_init(&sdev->starved_entry);
spin_unlock_irq(shost->host_lock);
}
return 1;
starved:
spin_lock_irq(shost->host_lock);
if (list_empty(&sdev->starved_entry))
list_add_tail(&sdev->starved_entry, &shost->starved_list);
spin_unlock_irq(shost->host_lock);
out_dec:
atomic_dec(&shost->host_busy);
return 0;
}
/*
* Busy state exporting function for request stacking drivers.
*
* For efficiency, no lock is taken to check the busy state of
* shost/starget/sdev, since the returned value is not guaranteed and
* may be changed after request stacking drivers call the function,
* regardless of taking lock or not.
*
* When scsi can't dispatch I/Os anymore and needs to kill I/Os scsi
* needs to return 'not busy'. Otherwise, request stacking drivers
* may hold requests forever.
*/
static int scsi_lld_busy(struct request_queue *q)
{
struct scsi_device *sdev = q->queuedata;
struct Scsi_Host *shost;
if (blk_queue_dying(q))
return 0;
shost = sdev->host;
/*
* Ignore host/starget busy state.
* Since block layer does not have a concept of fairness across
* multiple queues, congestion of host/starget needs to be handled
* in SCSI layer.
*/
if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev))
return 1;
return 0;
}
/*
* Kill a request for a dead device
*/
static void scsi_kill_request(struct request *req, struct request_queue *q)
{
struct scsi_cmnd *cmd = req->special;
struct scsi_device *sdev;
struct scsi_target *starget;
struct Scsi_Host *shost;
block: implement and enforce request peek/start/fetch Till now block layer allowed two separate modes of request execution. A request is always acquired from the request queue via elv_next_request(). After that, drivers are free to either dequeue it or process it without dequeueing. Dequeue allows elv_next_request() to return the next request so that multiple requests can be in flight. Executing requests without dequeueing has its merits mostly in allowing drivers for simpler devices which can't do sg to deal with segments only without considering request boundary. However, the benefit this brings is dubious and declining while the cost of the API ambiguity is increasing. Segment based drivers are usually for very old or limited devices and as converting to dequeueing model isn't difficult, it doesn't justify the API overhead it puts on block layer and its more modern users. Previous patches converted all block low level drivers to dequeueing model. This patch completes the API transition by... * renaming elv_next_request() to blk_peek_request() * renaming blkdev_dequeue_request() to blk_start_request() * adding blk_fetch_request() which is combination of peek and start * disallowing completion of queued (not started) requests * applying new API to all LLDs Renamings are for consistency and to break out of tree code so that it's apparent that out of tree drivers need updating. [ Impact: block request issue API cleanup, no functional change ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Mike Miller <mike.miller@hp.com> Cc: unsik Kim <donari75@gmail.com> Cc: Paul Clements <paul.clements@steeleye.com> Cc: Tim Waugh <tim@cyberelk.net> Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Cc: David S. Miller <davem@davemloft.net> Cc: Laurent Vivier <Laurent@lvivier.info> Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: Adrian McMenamin <adrian@mcmen.demon.co.uk> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Alex Dubov <oakad@yahoo.com> Cc: Pierre Ossman <drzeus@drzeus.cx> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Markus Lidel <Markus.Lidel@shadowconnect.com> Cc: Stefan Weinhuber <wein@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-08 02:54:16 +00:00
blk_start_request(req);
scmd_printk(KERN_INFO, cmd, "killing request\n");
sdev = cmd->device;
starget = scsi_target(sdev);
shost = sdev->host;
scsi_init_cmd_errh(cmd);
cmd->result = DID_NO_CONNECT << 16;
atomic_inc(&cmd->device->iorequest_cnt);
/*
* SCSI request completion path will do scsi_device_unbusy(),
* bump busy counts. To bump the counters, we need to dance
* with the locks as normal issue path does.
*/
atomic_inc(&sdev->device_busy);
atomic_inc(&shost->host_busy);
if (starget->can_queue > 0)
atomic_inc(&starget->target_busy);
blk_complete_request(req);
}
static void scsi_softirq_done(struct request *rq)
{
struct scsi_cmnd *cmd = rq->special;
unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
int disposition;
INIT_LIST_HEAD(&cmd->eh_entry);
atomic_inc(&cmd->device->iodone_cnt);
if (cmd->result)
atomic_inc(&cmd->device->ioerr_cnt);
disposition = scsi_decide_disposition(cmd);
if (disposition != SUCCESS &&
time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
sdev_printk(KERN_ERR, cmd->device,
"timing out command, waited %lus\n",
wait_for/HZ);
disposition = SUCCESS;
}
scsi_log_completion(cmd, disposition);
switch (disposition) {
case SUCCESS:
scsi_finish_command(cmd);
break;
case NEEDS_RETRY:
scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
break;
case ADD_TO_MLQUEUE:
scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
break;
default:
if (!scsi_eh_scmd_add(cmd, 0))
scsi_finish_command(cmd);
}
}
/**
* scsi_dispatch_command - Dispatch a command to the low-level driver.
* @cmd: command block we are dispatching.
*
* Return: nonzero return request was rejected and device's queue needs to be
* plugged.
*/
static int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
{
struct Scsi_Host *host = cmd->device->host;
int rtn = 0;
atomic_inc(&cmd->device->iorequest_cnt);
/* check if the device is still usable */
if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
/* in SDEV_DEL we error all commands. DID_NO_CONNECT
* returns an immediate error upwards, and signals
* that the device is no longer present */
cmd->result = DID_NO_CONNECT << 16;
goto done;
}
/* Check to see if the scsi lld made this device blocked. */
if (unlikely(scsi_device_blocked(cmd->device))) {
/*
* in blocked state, the command is just put back on
* the device queue. The suspend state has already
* blocked the queue so future requests should not
* occur until the device transitions out of the
* suspend state.
*/
SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
"queuecommand : device blocked\n"));
return SCSI_MLQUEUE_DEVICE_BUSY;
}
/* Store the LUN value in cmnd, if needed. */
if (cmd->device->lun_in_cdb)
cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
(cmd->device->lun << 5 & 0xe0);
scsi_log_send(cmd);
/*
* Before we queue this command, check if the command
* length exceeds what the host adapter can handle.
*/
if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
"queuecommand : command too long. "
"cdb_size=%d host->max_cmd_len=%d\n",
cmd->cmd_len, cmd->device->host->max_cmd_len));
cmd->result = (DID_ABORT << 16);
goto done;
}
if (unlikely(host->shost_state == SHOST_DEL)) {
cmd->result = (DID_NO_CONNECT << 16);
goto done;
}
trace_scsi_dispatch_cmd_start(cmd);
rtn = host->hostt->queuecommand(host, cmd);
if (rtn) {
trace_scsi_dispatch_cmd_error(cmd, rtn);
if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
rtn != SCSI_MLQUEUE_TARGET_BUSY)
rtn = SCSI_MLQUEUE_HOST_BUSY;
SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
"queuecommand : request rejected\n"));
}
return rtn;
done:
cmd->scsi_done(cmd);
return 0;
}
/**
* scsi_done - Invoke completion on finished SCSI command.
* @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
* ownership back to SCSI Core -- i.e. the LLDD has finished with it.
*
* Description: This function is the mid-level's (SCSI Core) interrupt routine,
* which regains ownership of the SCSI command (de facto) from a LLDD, and
* calls blk_complete_request() for further processing.
*
* This function is interrupt context safe.
*/
static void scsi_done(struct scsi_cmnd *cmd)
{
trace_scsi_dispatch_cmd_done(cmd);
blk_complete_request(cmd->request);
}
/*
* Function: scsi_request_fn()
*
* Purpose: Main strategy routine for SCSI.
*
* Arguments: q - Pointer to actual queue.
*
* Returns: Nothing
*
* Lock status: IO request lock assumed to be held when called.
*/
static void scsi_request_fn(struct request_queue *q)
__releases(q->queue_lock)
__acquires(q->queue_lock)
{
struct scsi_device *sdev = q->queuedata;
struct Scsi_Host *shost;
struct scsi_cmnd *cmd;
struct request *req;
/*
* To start with, we keep looping until the queue is empty, or until
* the host is no longer able to accept any more requests.
*/
shost = sdev->host;
for (;;) {
int rtn;
/*
* get next queueable request. We do this early to make sure
* that the request is fully prepared even if we cannot
* accept it.
*/
block: implement and enforce request peek/start/fetch Till now block layer allowed two separate modes of request execution. A request is always acquired from the request queue via elv_next_request(). After that, drivers are free to either dequeue it or process it without dequeueing. Dequeue allows elv_next_request() to return the next request so that multiple requests can be in flight. Executing requests without dequeueing has its merits mostly in allowing drivers for simpler devices which can't do sg to deal with segments only without considering request boundary. However, the benefit this brings is dubious and declining while the cost of the API ambiguity is increasing. Segment based drivers are usually for very old or limited devices and as converting to dequeueing model isn't difficult, it doesn't justify the API overhead it puts on block layer and its more modern users. Previous patches converted all block low level drivers to dequeueing model. This patch completes the API transition by... * renaming elv_next_request() to blk_peek_request() * renaming blkdev_dequeue_request() to blk_start_request() * adding blk_fetch_request() which is combination of peek and start * disallowing completion of queued (not started) requests * applying new API to all LLDs Renamings are for consistency and to break out of tree code so that it's apparent that out of tree drivers need updating. [ Impact: block request issue API cleanup, no functional change ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Mike Miller <mike.miller@hp.com> Cc: unsik Kim <donari75@gmail.com> Cc: Paul Clements <paul.clements@steeleye.com> Cc: Tim Waugh <tim@cyberelk.net> Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Cc: David S. Miller <davem@davemloft.net> Cc: Laurent Vivier <Laurent@lvivier.info> Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: Adrian McMenamin <adrian@mcmen.demon.co.uk> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Alex Dubov <oakad@yahoo.com> Cc: Pierre Ossman <drzeus@drzeus.cx> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Markus Lidel <Markus.Lidel@shadowconnect.com> Cc: Stefan Weinhuber <wein@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-08 02:54:16 +00:00
req = blk_peek_request(q);
if (!req)
break;
if (unlikely(!scsi_device_online(sdev))) {
sdev_printk(KERN_ERR, sdev,
"rejecting I/O to offline device\n");
scsi_kill_request(req, q);
continue;
}
if (!scsi_dev_queue_ready(q, sdev))
break;
/*
* Remove the request from the request list.
*/
if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
block: implement and enforce request peek/start/fetch Till now block layer allowed two separate modes of request execution. A request is always acquired from the request queue via elv_next_request(). After that, drivers are free to either dequeue it or process it without dequeueing. Dequeue allows elv_next_request() to return the next request so that multiple requests can be in flight. Executing requests without dequeueing has its merits mostly in allowing drivers for simpler devices which can't do sg to deal with segments only without considering request boundary. However, the benefit this brings is dubious and declining while the cost of the API ambiguity is increasing. Segment based drivers are usually for very old or limited devices and as converting to dequeueing model isn't difficult, it doesn't justify the API overhead it puts on block layer and its more modern users. Previous patches converted all block low level drivers to dequeueing model. This patch completes the API transition by... * renaming elv_next_request() to blk_peek_request() * renaming blkdev_dequeue_request() to blk_start_request() * adding blk_fetch_request() which is combination of peek and start * disallowing completion of queued (not started) requests * applying new API to all LLDs Renamings are for consistency and to break out of tree code so that it's apparent that out of tree drivers need updating. [ Impact: block request issue API cleanup, no functional change ] Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Mike Miller <mike.miller@hp.com> Cc: unsik Kim <donari75@gmail.com> Cc: Paul Clements <paul.clements@steeleye.com> Cc: Tim Waugh <tim@cyberelk.net> Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Cc: David S. Miller <davem@davemloft.net> Cc: Laurent Vivier <Laurent@lvivier.info> Cc: Jeff Garzik <jgarzik@pobox.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: Adrian McMenamin <adrian@mcmen.demon.co.uk> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Cc: Borislav Petkov <petkovbb@googlemail.com> Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com> Cc: Alex Dubov <oakad@yahoo.com> Cc: Pierre Ossman <drzeus@drzeus.cx> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Markus Lidel <Markus.Lidel@shadowconnect.com> Cc: Stefan Weinhuber <wein@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Pete Zaitcev <zaitcev@redhat.com> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-08 02:54:16 +00:00
blk_start_request(req);
spin_unlock_irq(q->queue_lock);
cmd = req->special;
if (unlikely(cmd == NULL)) {
printk(KERN_CRIT "impossible request in %s.\n"
"please mail a stack trace to "
"linux-scsi@vger.kernel.org\n",
__func__);
blk_dump_rq_flags(req, "foo");
BUG();
}
/*
* We hit this when the driver is using a host wide
* tag map. For device level tag maps the queue_depth check
* in the device ready fn would prevent us from trying
* to allocate a tag. Since the map is a shared host resource
* we add the dev to the starved list so it eventually gets
* a run when a tag is freed.
*/
if (blk_queue_tagged(q) && !(req->rq_flags & RQF_QUEUED)) {
spin_lock_irq(shost->host_lock);
if (list_empty(&sdev->starved_entry))
list_add_tail(&sdev->starved_entry,
&shost->starved_list);
spin_unlock_irq(shost->host_lock);
goto not_ready;
}
[SCSI] Add helper code so transport classes/driver can control queueing (v3) SCSI-ml manages the queueing limits for the device and host, but does not do so at the target level. However something something similar can come in userful when a driver is transitioning a transport object to the the blocked state, becuase at that time we do not want to queue io and we do not want the queuecommand to be called again. The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers. You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit a transport level queueing issue like the hw cannot allocate some resource at the iscsi session/connection level, or the target has temporarily closed or shrunk the queueing window, or if we are transitioning to the blocked state. bnx2i, when they rework their firmware according to netdev developers requests, will also need to be able to limit queueing at this level. bnx2i will hook into libiscsi, but will allocate a scsi host per netdevice/hba, so unlike pure software iscsi/iser which is allocating a host per session, it cannot set the scsi_host->can_queue and return SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport. The iscsi class/driver can also set a scsi_target->can_queue value which reflects the max commands the driver/class can support. For iscsi this reflects the number of commands we can support for each session due to session/connection hw limits, driver limits, and to also reflect the session/targets's queueing window. Changes: v1 - initial patch. v2 - Fix scsi_run_queue handling of multiple blocked targets. Previously we would break from the main loop if a device was added back on the starved list. We now run over the list and check if any target is blocked. v3 - Rediff for scsi-misc. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-08-17 20:24:38 +00:00
if (!scsi_target_queue_ready(shost, sdev))
goto not_ready;
if (!scsi_host_queue_ready(q, shost, sdev))
goto host_not_ready;
if (sdev->simple_tags)
cmd->flags |= SCMD_TAGGED;
else
cmd->flags &= ~SCMD_TAGGED;
/*
* Finally, initialize any error handling parameters, and set up
* the timers for timeouts.
*/
scsi_init_cmd_errh(cmd);
/*
* Dispatch the command to the low-level driver.
*/
cmd->scsi_done = scsi_done;
rtn = scsi_dispatch_cmd(cmd);
if (rtn) {
scsi_queue_insert(cmd, rtn);
spin_lock_irq(q->queue_lock);
goto out_delay;
}
spin_lock_irq(q->queue_lock);
}
return;
host_not_ready:
if (scsi_target(sdev)->can_queue > 0)
atomic_dec(&scsi_target(sdev)->target_busy);
not_ready:
/*
* lock q, handle tag, requeue req, and decrement device_busy. We
* must return with queue_lock held.
*
* Decrementing device_busy without checking it is OK, as all such
* cases (host limits or settings) should run the queue at some
* later time.
*/
spin_lock_irq(q->queue_lock);
blk_requeue_request(q, req);
atomic_dec(&sdev->device_busy);
out_delay:
if (!atomic_read(&sdev->device_busy) && !scsi_device_blocked(sdev))
blk_delay_queue(q, SCSI_QUEUE_DELAY);
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
static inline int prep_to_mq(int ret)
{
switch (ret) {
case BLKPREP_OK:
return BLK_MQ_RQ_QUEUE_OK;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
case BLKPREP_DEFER:
return BLK_MQ_RQ_QUEUE_BUSY;
default:
return BLK_MQ_RQ_QUEUE_ERROR;
}
}
static int scsi_mq_prep_fn(struct request *req)
{
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
struct scsi_device *sdev = req->q->queuedata;
struct Scsi_Host *shost = sdev->host;
unsigned char *sense_buf = cmd->sense_buffer;
struct scatterlist *sg;
/* zero out the cmd, except for the embedded scsi_request */
memset((char *)cmd + sizeof(cmd->req), 0,
sizeof(*cmd) - sizeof(cmd->req));
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
req->special = cmd;
cmd->request = req;
cmd->device = sdev;
cmd->sense_buffer = sense_buf;
cmd->tag = req->tag;
cmd->prot_op = SCSI_PROT_NORMAL;
INIT_LIST_HEAD(&cmd->list);
INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
cmd->jiffies_at_alloc = jiffies;
if (shost->use_cmd_list) {
spin_lock_irq(&sdev->list_lock);
list_add_tail(&cmd->list, &sdev->cmd_list);
spin_unlock_irq(&sdev->list_lock);
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
cmd->sdb.table.sgl = sg;
if (scsi_host_get_prot(shost)) {
cmd->prot_sdb = (void *)sg +
min_t(unsigned int,
shost->sg_tablesize, SG_CHUNK_SIZE) *
sizeof(struct scatterlist);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
cmd->prot_sdb->table.sgl =
(struct scatterlist *)(cmd->prot_sdb + 1);
}
if (blk_bidi_rq(req)) {
struct request *next_rq = req->next_rq;
struct scsi_data_buffer *bidi_sdb = blk_mq_rq_to_pdu(next_rq);
memset(bidi_sdb, 0, sizeof(struct scsi_data_buffer));
bidi_sdb->table.sgl =
(struct scatterlist *)(bidi_sdb + 1);
next_rq->special = bidi_sdb;
}
blk_mq_start_request(req);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
return scsi_setup_cmnd(sdev, req);
}
static void scsi_mq_done(struct scsi_cmnd *cmd)
{
trace_scsi_dispatch_cmd_done(cmd);
blk_mq_complete_request(cmd->request, cmd->request->errors);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
}
static int scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
{
struct request *req = bd->rq;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
struct request_queue *q = req->q;
struct scsi_device *sdev = q->queuedata;
struct Scsi_Host *shost = sdev->host;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
int ret;
int reason;
ret = prep_to_mq(scsi_prep_state_check(sdev, req));
if (ret != BLK_MQ_RQ_QUEUE_OK)
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
goto out;
ret = BLK_MQ_RQ_QUEUE_BUSY;
if (!get_device(&sdev->sdev_gendev))
goto out;
if (!scsi_dev_queue_ready(q, sdev))
goto out_put_device;
if (!scsi_target_queue_ready(shost, sdev))
goto out_dec_device_busy;
if (!scsi_host_queue_ready(q, shost, sdev))
goto out_dec_target_busy;
if (!(req->rq_flags & RQF_DONTPREP)) {
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
ret = prep_to_mq(scsi_mq_prep_fn(req));
if (ret != BLK_MQ_RQ_QUEUE_OK)
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
goto out_dec_host_busy;
req->rq_flags |= RQF_DONTPREP;
} else {
blk_mq_start_request(req);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
}
if (sdev->simple_tags)
cmd->flags |= SCMD_TAGGED;
else
cmd->flags &= ~SCMD_TAGGED;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
scsi_init_cmd_errh(cmd);
cmd->scsi_done = scsi_mq_done;
reason = scsi_dispatch_cmd(cmd);
if (reason) {
scsi_set_blocked(cmd, reason);
ret = BLK_MQ_RQ_QUEUE_BUSY;
goto out_dec_host_busy;
}
return BLK_MQ_RQ_QUEUE_OK;
out_dec_host_busy:
atomic_dec(&shost->host_busy);
out_dec_target_busy:
if (scsi_target(sdev)->can_queue > 0)
atomic_dec(&scsi_target(sdev)->target_busy);
out_dec_device_busy:
atomic_dec(&sdev->device_busy);
out_put_device:
put_device(&sdev->sdev_gendev);
out:
switch (ret) {
case BLK_MQ_RQ_QUEUE_BUSY:
if (atomic_read(&sdev->device_busy) == 0 &&
!scsi_device_blocked(sdev))
blk_mq_delay_queue(hctx, SCSI_QUEUE_DELAY);
break;
case BLK_MQ_RQ_QUEUE_ERROR:
/*
* Make sure to release all allocated ressources when
* we hit an error, as we will never see this command
* again.
*/
if (req->rq_flags & RQF_DONTPREP)
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
scsi_mq_uninit_cmd(cmd);
break;
default:
break;
}
return ret;
}
static enum blk_eh_timer_return scsi_timeout(struct request *req,
bool reserved)
{
if (reserved)
return BLK_EH_RESET_TIMER;
return scsi_times_out(req);
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
static int scsi_init_request(void *data, struct request *rq,
unsigned int hctx_idx, unsigned int request_idx,
unsigned int numa_node)
{
struct Scsi_Host *shost = data;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
cmd->sense_buffer =
scsi_alloc_sense_buffer(shost, GFP_KERNEL, numa_node);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (!cmd->sense_buffer)
return -ENOMEM;
cmd->req.sense = cmd->sense_buffer;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
return 0;
}
static void scsi_exit_request(void *data, struct request *rq,
unsigned int hctx_idx, unsigned int request_idx)
{
struct Scsi_Host *shost = data;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
scsi_free_sense_buffer(shost, cmd->sense_buffer);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
}
static int scsi_map_queues(struct blk_mq_tag_set *set)
{
struct Scsi_Host *shost = container_of(set, struct Scsi_Host, tag_set);
if (shost->hostt->map_queues)
return shost->hostt->map_queues(shost);
return blk_mq_map_queues(set);
}
static u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
{
struct device *host_dev;
u64 bounce_limit = 0xffffffff;
if (shost->unchecked_isa_dma)
return BLK_BOUNCE_ISA;
/*
* Platforms with virtual-DMA translation
* hardware have no practical limit.
*/
if (!PCI_DMA_BUS_IS_PHYS)
return BLK_BOUNCE_ANY;
host_dev = scsi_get_device(shost);
if (host_dev && host_dev->dma_mask)
bounce_limit = (u64)dma_max_pfn(host_dev) << PAGE_SHIFT;
return bounce_limit;
}
void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
{
struct device *dev = shost->dma_dev;
/*
* this limit is imposed by hardware restrictions
*/
blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
SG_MAX_SEGMENTS));
if (scsi_host_prot_dma(shost)) {
shost->sg_prot_tablesize =
min_not_zero(shost->sg_prot_tablesize,
(unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
}
blk_queue_max_hw_sectors(q, shost->max_sectors);
blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
blk_queue_segment_boundary(q, shost->dma_boundary);
dma_set_seg_boundary(dev, shost->dma_boundary);
blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
if (!shost->use_clustering)
q->limits.cluster = 0;
/*
* set a reasonable default alignment on word boundaries: the
* host and device may alter it using
* blk_queue_update_dma_alignment() later.
*/
blk_queue_dma_alignment(q, 0x03);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
}
EXPORT_SYMBOL_GPL(__scsi_init_queue);
static int scsi_init_rq(struct request_queue *q, struct request *rq, gfp_t gfp)
{
struct Scsi_Host *shost = q->rq_alloc_data;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
memset(cmd, 0, sizeof(*cmd));
cmd->sense_buffer = scsi_alloc_sense_buffer(shost, gfp, NUMA_NO_NODE);
if (!cmd->sense_buffer)
goto fail;
cmd->req.sense = cmd->sense_buffer;
if (scsi_host_get_prot(shost) >= SHOST_DIX_TYPE0_PROTECTION) {
cmd->prot_sdb = kmem_cache_zalloc(scsi_sdb_cache, gfp);
if (!cmd->prot_sdb)
goto fail_free_sense;
}
return 0;
fail_free_sense:
scsi_free_sense_buffer(shost, cmd->sense_buffer);
fail:
return -ENOMEM;
}
static void scsi_exit_rq(struct request_queue *q, struct request *rq)
{
struct Scsi_Host *shost = q->rq_alloc_data;
struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
if (cmd->prot_sdb)
kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
scsi_free_sense_buffer(shost, cmd->sense_buffer);
}
struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
{
struct Scsi_Host *shost = sdev->host;
struct request_queue *q;
q = blk_alloc_queue_node(GFP_KERNEL, NUMA_NO_NODE);
if (!q)
return NULL;
q->cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
q->rq_alloc_data = shost;
q->request_fn = scsi_request_fn;
q->init_rq_fn = scsi_init_rq;
q->exit_rq_fn = scsi_exit_rq;
if (blk_init_allocated_queue(q) < 0) {
blk_cleanup_queue(q);
return NULL;
}
__scsi_init_queue(shost, q);
blk_queue_prep_rq(q, scsi_prep_fn);
blk_queue_unprep_rq(q, scsi_unprep_fn);
blk_queue_softirq_done(q, scsi_softirq_done);
blk_queue_rq_timed_out(q, scsi_times_out);
blk_queue_lld_busy(q, scsi_lld_busy);
return q;
}
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
static struct blk_mq_ops scsi_mq_ops = {
.queue_rq = scsi_queue_rq,
.complete = scsi_softirq_done,
.timeout = scsi_timeout,
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
.init_request = scsi_init_request,
.exit_request = scsi_exit_request,
.map_queues = scsi_map_queues,
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
};
struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
{
sdev->request_queue = blk_mq_init_queue(&sdev->host->tag_set);
if (IS_ERR(sdev->request_queue))
return NULL;
sdev->request_queue->queuedata = sdev;
__scsi_init_queue(sdev->host, sdev->request_queue);
return sdev->request_queue;
}
int scsi_mq_setup_tags(struct Scsi_Host *shost)
{
unsigned int cmd_size, sgl_size, tbl_size;
tbl_size = shost->sg_tablesize;
if (tbl_size > SG_CHUNK_SIZE)
tbl_size = SG_CHUNK_SIZE;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
sgl_size = tbl_size * sizeof(struct scatterlist);
cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size;
if (scsi_host_get_prot(shost))
cmd_size += sizeof(struct scsi_data_buffer) + sgl_size;
memset(&shost->tag_set, 0, sizeof(shost->tag_set));
shost->tag_set.ops = &scsi_mq_ops;
shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
shost->tag_set.queue_depth = shost->can_queue;
shost->tag_set.cmd_size = cmd_size;
shost->tag_set.numa_node = NUMA_NO_NODE;
shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
shost->tag_set.flags |=
BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
shost->tag_set.driver_data = shost;
return blk_mq_alloc_tag_set(&shost->tag_set);
}
void scsi_mq_destroy_tags(struct Scsi_Host *shost)
{
blk_mq_free_tag_set(&shost->tag_set);
}
/*
* Function: scsi_block_requests()
*
* Purpose: Utility function used by low-level drivers to prevent further
* commands from being queued to the device.
*
* Arguments: shost - Host in question
*
* Returns: Nothing
*
* Lock status: No locks are assumed held.
*
* Notes: There is no timer nor any other means by which the requests
* get unblocked other than the low-level driver calling
* scsi_unblock_requests().
*/
void scsi_block_requests(struct Scsi_Host *shost)
{
shost->host_self_blocked = 1;
}
EXPORT_SYMBOL(scsi_block_requests);
/*
* Function: scsi_unblock_requests()
*
* Purpose: Utility function used by low-level drivers to allow further
* commands from being queued to the device.
*
* Arguments: shost - Host in question
*
* Returns: Nothing
*
* Lock status: No locks are assumed held.
*
* Notes: There is no timer nor any other means by which the requests
* get unblocked other than the low-level driver calling
* scsi_unblock_requests().
*
* This is done as an API function so that changes to the
* internals of the scsi mid-layer won't require wholesale
* changes to drivers that use this feature.
*/
void scsi_unblock_requests(struct Scsi_Host *shost)
{
shost->host_self_blocked = 0;
scsi_run_host_queues(shost);
}
EXPORT_SYMBOL(scsi_unblock_requests);
int __init scsi_init_queue(void)
{
scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
sizeof(struct scsi_data_buffer),
0, 0, NULL);
if (!scsi_sdb_cache) {
printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
return -ENOMEM;
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
}
return 0;
}
void scsi_exit_queue(void)
{
kmem_cache_destroy(scsi_sense_cache);
kmem_cache_destroy(scsi_sense_isadma_cache);
kmem_cache_destroy(scsi_sdb_cache);
}
/**
* scsi_mode_select - issue a mode select
* @sdev: SCSI device to be queried
* @pf: Page format bit (1 == standard, 0 == vendor specific)
* @sp: Save page bit (0 == don't save, 1 == save)
* @modepage: mode page being requested
* @buffer: request buffer (may not be smaller than eight bytes)
* @len: length of request buffer.
* @timeout: command timeout
* @retries: number of retries before failing
* @data: returns a structure abstracting the mode header data
* @sshdr: place to put sense data (or NULL if no sense to be collected).
* must be SCSI_SENSE_BUFFERSIZE big.
*
* Returns zero if successful; negative error number or scsi
* status on error
*
*/
int
scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
unsigned char *buffer, int len, int timeout, int retries,
struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
{
unsigned char cmd[10];
unsigned char *real_buffer;
int ret;
memset(cmd, 0, sizeof(cmd));
cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
if (sdev->use_10_for_ms) {
if (len > 65535)
return -EINVAL;
real_buffer = kmalloc(8 + len, GFP_KERNEL);
if (!real_buffer)
return -ENOMEM;
memcpy(real_buffer + 8, buffer, len);
len += 8;
real_buffer[0] = 0;
real_buffer[1] = 0;
real_buffer[2] = data->medium_type;
real_buffer[3] = data->device_specific;
real_buffer[4] = data->longlba ? 0x01 : 0;
real_buffer[5] = 0;
real_buffer[6] = data->block_descriptor_length >> 8;
real_buffer[7] = data->block_descriptor_length;
cmd[0] = MODE_SELECT_10;
cmd[7] = len >> 8;
cmd[8] = len;
} else {
if (len > 255 || data->block_descriptor_length > 255 ||
data->longlba)
return -EINVAL;
real_buffer = kmalloc(4 + len, GFP_KERNEL);
if (!real_buffer)
return -ENOMEM;
memcpy(real_buffer + 4, buffer, len);
len += 4;
real_buffer[0] = 0;
real_buffer[1] = data->medium_type;
real_buffer[2] = data->device_specific;
real_buffer[3] = data->block_descriptor_length;
cmd[0] = MODE_SELECT;
cmd[4] = len;
}
ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
sshdr, timeout, retries, NULL);
kfree(real_buffer);
return ret;
}
EXPORT_SYMBOL_GPL(scsi_mode_select);
/**
* scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
* @sdev: SCSI device to be queried
* @dbd: set if mode sense will allow block descriptors to be returned
* @modepage: mode page being requested
* @buffer: request buffer (may not be smaller than eight bytes)
* @len: length of request buffer.
* @timeout: command timeout
* @retries: number of retries before failing
* @data: returns a structure abstracting the mode header data
* @sshdr: place to put sense data (or NULL if no sense to be collected).
* must be SCSI_SENSE_BUFFERSIZE big.
*
* Returns zero if unsuccessful, or the header offset (either 4
* or 8 depending on whether a six or ten byte command was
* issued) if successful.
*/
int
scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
unsigned char *buffer, int len, int timeout, int retries,
struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
{
unsigned char cmd[12];
int use_10_for_ms;
int header_length;
int result, retry_count = retries;
struct scsi_sense_hdr my_sshdr;
memset(data, 0, sizeof(*data));
memset(&cmd[0], 0, 12);
cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
cmd[2] = modepage;
/* caller might not be interested in sense, but we need it */
if (!sshdr)
sshdr = &my_sshdr;
retry:
use_10_for_ms = sdev->use_10_for_ms;
if (use_10_for_ms) {
if (len < 8)
len = 8;
cmd[0] = MODE_SENSE_10;
cmd[8] = len;
header_length = 8;
} else {
if (len < 4)
len = 4;
cmd[0] = MODE_SENSE;
cmd[4] = len;
header_length = 4;
}
memset(buffer, 0, len);
result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
sshdr, timeout, retries, NULL);
/* This code looks awful: what it's doing is making sure an
* ILLEGAL REQUEST sense return identifies the actual command
* byte as the problem. MODE_SENSE commands can return
* ILLEGAL REQUEST if the code page isn't supported */
if (use_10_for_ms && !scsi_status_is_good(result) &&
(driver_byte(result) & DRIVER_SENSE)) {
if (scsi_sense_valid(sshdr)) {
if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
(sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
/*
* Invalid command operation code
*/
sdev->use_10_for_ms = 0;
goto retry;
}
}
}
if(scsi_status_is_good(result)) {
if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
(modepage == 6 || modepage == 8))) {
/* Initio breakage? */
header_length = 0;
data->length = 13;
data->medium_type = 0;
data->device_specific = 0;
data->longlba = 0;
data->block_descriptor_length = 0;
} else if(use_10_for_ms) {
data->length = buffer[0]*256 + buffer[1] + 2;
data->medium_type = buffer[2];
data->device_specific = buffer[3];
data->longlba = buffer[4] & 0x01;
data->block_descriptor_length = buffer[6]*256
+ buffer[7];
} else {
data->length = buffer[0] + 1;
data->medium_type = buffer[1];
data->device_specific = buffer[2];
data->block_descriptor_length = buffer[3];
}
data->header_length = header_length;
} else if ((status_byte(result) == CHECK_CONDITION) &&
scsi_sense_valid(sshdr) &&
sshdr->sense_key == UNIT_ATTENTION && retry_count) {
retry_count--;
goto retry;
}
return result;
}
EXPORT_SYMBOL(scsi_mode_sense);
/**
* scsi_test_unit_ready - test if unit is ready
* @sdev: scsi device to change the state of.
* @timeout: command timeout
* @retries: number of retries before failing
* @sshdr_external: Optional pointer to struct scsi_sense_hdr for
* returning sense. Make sure that this is cleared before passing
* in.
*
* Returns zero if unsuccessful or an error if TUR failed. For
* removable media, UNIT_ATTENTION sets ->changed flag.
**/
int
scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
struct scsi_sense_hdr *sshdr_external)
{
char cmd[] = {
TEST_UNIT_READY, 0, 0, 0, 0, 0,
};
struct scsi_sense_hdr *sshdr;
int result;
if (!sshdr_external)
sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
else
sshdr = sshdr_external;
/* try to eat the UNIT_ATTENTION if there are enough retries */
do {
result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
timeout, retries, NULL);
if (sdev->removable && scsi_sense_valid(sshdr) &&
sshdr->sense_key == UNIT_ATTENTION)
sdev->changed = 1;
} while (scsi_sense_valid(sshdr) &&
sshdr->sense_key == UNIT_ATTENTION && --retries);
if (!sshdr_external)
kfree(sshdr);
return result;
}
EXPORT_SYMBOL(scsi_test_unit_ready);
/**
* scsi_device_set_state - Take the given device through the device state model.
* @sdev: scsi device to change the state of.
* @state: state to change to.
*
* Returns zero if unsuccessful or an error if the requested
* transition is illegal.
*/
int
scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
{
enum scsi_device_state oldstate = sdev->sdev_state;
if (state == oldstate)
return 0;
switch (state) {
case SDEV_CREATED:
switch (oldstate) {
case SDEV_CREATED_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_RUNNING:
switch (oldstate) {
case SDEV_CREATED:
case SDEV_OFFLINE:
case SDEV_TRANSPORT_OFFLINE:
case SDEV_QUIESCE:
case SDEV_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_QUIESCE:
switch (oldstate) {
case SDEV_RUNNING:
case SDEV_OFFLINE:
case SDEV_TRANSPORT_OFFLINE:
break;
default:
goto illegal;
}
break;
case SDEV_OFFLINE:
case SDEV_TRANSPORT_OFFLINE:
switch (oldstate) {
case SDEV_CREATED:
case SDEV_RUNNING:
case SDEV_QUIESCE:
case SDEV_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_BLOCK:
switch (oldstate) {
case SDEV_RUNNING:
case SDEV_CREATED_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_CREATED_BLOCK:
switch (oldstate) {
case SDEV_CREATED:
break;
default:
goto illegal;
}
break;
case SDEV_CANCEL:
switch (oldstate) {
case SDEV_CREATED:
case SDEV_RUNNING:
case SDEV_QUIESCE:
case SDEV_OFFLINE:
case SDEV_TRANSPORT_OFFLINE:
case SDEV_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_DEL:
switch (oldstate) {
[SCSI] scsi: Device scanning oops for offlined devices (resend) If a device gets offlined as a result of the Inquiry sent during scanning, the following oops can occur. After the disk gets put into the SDEV_OFFLINE state, the error handler sends back the failed inquiry, which wakes the thread doing the scan. This starts a race between the scanning thread freeing the scsi device and the error handler calling scsi_run_host_queues to restart the host. Since the disk is in the SDEV_OFFLINE state, scsi_device_get will still work, which results in __scsi_iterate_devices getting a reference to the scsi disk when it shouldn't. The following execution thread causes the oops: CPU 0 (scan) CPU 1 (eh) --------------------------------------------------------- scsi_probe_and_add_lun .... scsi_eh_offline_sdevs scsi_eh_flush_done_q scsi_destroy_sdev scsi_device_dev_release scsi_restart_operations scsi_run_host_queues __scsi_iterate_devices get_device scsi_device_dev_release_usercontext scsi_run_queue <---OOPS---> The patch fixes this by changing the state of the sdev to SDEV_DEL before doing the final put_device, which should prevent the race from occurring. Original oops follows: Badness in kref_get at lib/kref.c:32 Call Trace: [C00000002F4476D0] [C00000000000EE20] .show_stack+0x68/0x1b0 (unreliable) [C00000002F447770] [C00000000037515C] .program_check_exception+0x1cc/0x5a8 [C00000002F447840] [C00000000000446C] program_check_common+0xec/0x100 Exception: 700 at .kref_get+0x10/0x28 LR = .kobject_get+0x20/0x3c [C00000002F447B30] [C00000002F447BC0] 0xc00000002f447bc0 (unreliable) [C00000002F447BB0] [C000000000254BDC] .get_device+0x20/0x3c [C00000002F447C30] [D000000000063188] .scsi_device_get+0x34/0xdc [scsi_mod] [C00000002F447CC0] [D0000000000633EC] .__scsi_iterate_devices+0x50/0xbc [scsi_mod] [C00000002F447D60] [D00000000006A910] .scsi_run_host_queues+0x34/0x5c [scsi_mod] [C00000002F447DF0] [D000000000069054] .scsi_error_handler+0xdb4/0xe44 [scsi_mod] [C00000002F447EE0] [C00000000007B4E0] .kthread+0x128/0x178 [C00000002F447F90] [C000000000025E84] .kernel_thread+0x4c/0x68 Unable to handle kernel paging request for <7>PCI: Enabling device: (0002:41:01.1), cmd 143 data at address 0x000001b8 Faulting instruction address: 0xd0000000000698e4 sym1: <1010-66> rev 0x1 at pci 0002:41:01.1 irq 216 sym1: No NVRAM, ID 7, Fast-80, LVD, parity checking sym1: SCSI BUS has been reset. scsi2 : sym-2.2.2 cpu 0x0: Vector: 300 (Data Access) at [c00000002f447a30] pc: d0000000000698e4: .scsi_run_queue+0x2c/0x218 [scsi_mod] lr: d00000000006a904: .scsi_run_host_queues+0x28/0x5c [scsi_mod] sp: c00000002f447cb0 msr: 9000000000009032 dar: 1b8 dsisr: 40000000 current = 0xc0000000045fecd0 paca = 0xc00000000048ee80 pid = 1123, comm = scsi_eh_1 enter ? for help [c00000002f447d60] d00000000006a904 .scsi_run_host_queues+0x28/0x5c [scsi_mod] [c00000002f447df0] d000000000069054 .scsi_error_handler+0xdb4/0xe44 [scsi_mod] [c00000002f447ee0] c00000000007b4e0 .kthread+0x128/0x178 [c00000002f447f90] c000000000025e84 .kernel_thread+0x4c/0x68 Signed-off-by: Brian King <brking@us.ibm.com> Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-06-27 16:10:43 +00:00
case SDEV_CREATED:
case SDEV_RUNNING:
case SDEV_OFFLINE:
case SDEV_TRANSPORT_OFFLINE:
case SDEV_CANCEL:
case SDEV_CREATED_BLOCK:
break;
default:
goto illegal;
}
break;
}
sdev->sdev_state = state;
return 0;
illegal:
SCSI_LOG_ERROR_RECOVERY(1,
sdev_printk(KERN_ERR, sdev,
"Illegal state transition %s->%s",
scsi_device_state_name(oldstate),
scsi_device_state_name(state))
);
return -EINVAL;
}
EXPORT_SYMBOL(scsi_device_set_state);
/**
* sdev_evt_emit - emit a single SCSI device uevent
* @sdev: associated SCSI device
* @evt: event to emit
*
* Send a single uevent (scsi_event) to the associated scsi_device.
*/
static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
{
int idx = 0;
char *envp[3];
switch (evt->evt_type) {
case SDEV_EVT_MEDIA_CHANGE:
envp[idx++] = "SDEV_MEDIA_CHANGE=1";
break;
case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
scsi_rescan_device(&sdev->sdev_gendev);
envp[idx++] = "SDEV_UA=INQUIRY_DATA_HAS_CHANGED";
break;
case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
envp[idx++] = "SDEV_UA=CAPACITY_DATA_HAS_CHANGED";
break;
case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
envp[idx++] = "SDEV_UA=THIN_PROVISIONING_SOFT_THRESHOLD_REACHED";
break;
case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
envp[idx++] = "SDEV_UA=MODE_PARAMETERS_CHANGED";
break;
case SDEV_EVT_LUN_CHANGE_REPORTED:
envp[idx++] = "SDEV_UA=REPORTED_LUNS_DATA_HAS_CHANGED";
break;
case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
envp[idx++] = "SDEV_UA=ASYMMETRIC_ACCESS_STATE_CHANGED";
break;
default:
/* do nothing */
break;
}
envp[idx++] = NULL;
kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
}
/**
* sdev_evt_thread - send a uevent for each scsi event
* @work: work struct for scsi_device
*
* Dispatch queued events to their associated scsi_device kobjects
* as uevents.
*/
void scsi_evt_thread(struct work_struct *work)
{
struct scsi_device *sdev;
enum scsi_device_event evt_type;
LIST_HEAD(event_list);
sdev = container_of(work, struct scsi_device, event_work);
for (evt_type = SDEV_EVT_FIRST; evt_type <= SDEV_EVT_LAST; evt_type++)
if (test_and_clear_bit(evt_type, sdev->pending_events))
sdev_evt_send_simple(sdev, evt_type, GFP_KERNEL);
while (1) {
struct scsi_event *evt;
struct list_head *this, *tmp;
unsigned long flags;
spin_lock_irqsave(&sdev->list_lock, flags);
list_splice_init(&sdev->event_list, &event_list);
spin_unlock_irqrestore(&sdev->list_lock, flags);
if (list_empty(&event_list))
break;
list_for_each_safe(this, tmp, &event_list) {
evt = list_entry(this, struct scsi_event, node);
list_del(&evt->node);
scsi_evt_emit(sdev, evt);
kfree(evt);
}
}
}
/**
* sdev_evt_send - send asserted event to uevent thread
* @sdev: scsi_device event occurred on
* @evt: event to send
*
* Assert scsi device event asynchronously.
*/
void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
{
unsigned long flags;
#if 0
/* FIXME: currently this check eliminates all media change events
* for polled devices. Need to update to discriminate between AN
* and polled events */
if (!test_bit(evt->evt_type, sdev->supported_events)) {
kfree(evt);
return;
}
#endif
spin_lock_irqsave(&sdev->list_lock, flags);
list_add_tail(&evt->node, &sdev->event_list);
schedule_work(&sdev->event_work);
spin_unlock_irqrestore(&sdev->list_lock, flags);
}
EXPORT_SYMBOL_GPL(sdev_evt_send);
/**
* sdev_evt_alloc - allocate a new scsi event
* @evt_type: type of event to allocate
* @gfpflags: GFP flags for allocation
*
* Allocates and returns a new scsi_event.
*/
struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
gfp_t gfpflags)
{
struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
if (!evt)
return NULL;
evt->evt_type = evt_type;
INIT_LIST_HEAD(&evt->node);
/* evt_type-specific initialization, if any */
switch (evt_type) {
case SDEV_EVT_MEDIA_CHANGE:
case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
case SDEV_EVT_LUN_CHANGE_REPORTED:
case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
default:
/* do nothing */
break;
}
return evt;
}
EXPORT_SYMBOL_GPL(sdev_evt_alloc);
/**
* sdev_evt_send_simple - send asserted event to uevent thread
* @sdev: scsi_device event occurred on
* @evt_type: type of event to send
* @gfpflags: GFP flags for allocation
*
* Assert scsi device event asynchronously, given an event type.
*/
void sdev_evt_send_simple(struct scsi_device *sdev,
enum scsi_device_event evt_type, gfp_t gfpflags)
{
struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
if (!evt) {
sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
evt_type);
return;
}
sdev_evt_send(sdev, evt);
}
EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
/**
* scsi_request_fn_active() - number of kernel threads inside scsi_request_fn()
* @sdev: SCSI device to count the number of scsi_request_fn() callers for.
*/
static int scsi_request_fn_active(struct scsi_device *sdev)
{
struct request_queue *q = sdev->request_queue;
int request_fn_active;
WARN_ON_ONCE(sdev->host->use_blk_mq);
spin_lock_irq(q->queue_lock);
request_fn_active = q->request_fn_active;
spin_unlock_irq(q->queue_lock);
return request_fn_active;
}
/**
* scsi_wait_for_queuecommand() - wait for ongoing queuecommand() calls
* @sdev: SCSI device pointer.
*
* Wait until the ongoing shost->hostt->queuecommand() calls that are
* invoked from scsi_request_fn() have finished.
*/
static void scsi_wait_for_queuecommand(struct scsi_device *sdev)
{
WARN_ON_ONCE(sdev->host->use_blk_mq);
while (scsi_request_fn_active(sdev))
msleep(20);
}
/**
* scsi_device_quiesce - Block user issued commands.
* @sdev: scsi device to quiesce.
*
* This works by trying to transition to the SDEV_QUIESCE state
* (which must be a legal transition). When the device is in this
* state, only special requests will be accepted, all others will
* be deferred. Since special requests may also be requeued requests,
* a successful return doesn't guarantee the device will be
* totally quiescent.
*
* Must be called with user context, may sleep.
*
* Returns zero if unsuccessful or an error if not.
*/
int
scsi_device_quiesce(struct scsi_device *sdev)
{
int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
if (err)
return err;
scsi_run_queue(sdev->request_queue);
while (atomic_read(&sdev->device_busy)) {
msleep_interruptible(200);
scsi_run_queue(sdev->request_queue);
}
return 0;
}
EXPORT_SYMBOL(scsi_device_quiesce);
/**
* scsi_device_resume - Restart user issued commands to a quiesced device.
* @sdev: scsi device to resume.
*
* Moves the device from quiesced back to running and restarts the
* queues.
*
* Must be called with user context, may sleep.
*/
[SCSI] sd: limit the scope of the async probe domain sd injects and synchronizes probe work on the global kernel-wide domain. This runs into conflict with PM that wants to perform resume actions in async context: [ 494.237079] INFO: task kworker/u:3:554 blocked for more than 120 seconds. [ 494.294396] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 494.360809] kworker/u:3 D 0000000000000000 0 554 2 0x00000000 [ 494.420739] ffff88012e4d3af0 0000000000000046 ffff88013200c160 ffff88012e4d3fd8 [ 494.484392] ffff88012e4d3fd8 0000000000012500 ffff8801394ea0b0 ffff88013200c160 [ 494.548038] ffff88012e4d3ae0 00000000000001e3 ffffffff81a249e0 ffff8801321c5398 [ 494.611685] Call Trace: [ 494.632649] [<ffffffff8149dd25>] schedule+0x5a/0x5c [ 494.674687] [<ffffffff8104b968>] async_synchronize_cookie_domain+0xb6/0x112 [ 494.734177] [<ffffffff810461ff>] ? __init_waitqueue_head+0x50/0x50 [ 494.787134] [<ffffffff8131a224>] ? scsi_remove_target+0x48/0x48 [ 494.837900] [<ffffffff8104b9d9>] async_synchronize_cookie+0x15/0x17 [ 494.891567] [<ffffffff8104ba49>] async_synchronize_full+0x54/0x70 <-- here we wait for async contexts to complete [ 494.943783] [<ffffffff8104b9f5>] ? async_synchronize_full_domain+0x1a/0x1a [ 495.002547] [<ffffffffa00114b1>] sd_remove+0x2c/0xa2 [sd_mod] [ 495.051861] [<ffffffff812fe94f>] __device_release_driver+0x86/0xcf [ 495.104807] [<ffffffff812fe9bd>] device_release_driver+0x25/0x32 <-- here we take device_lock() [ 853.511341] INFO: task kworker/u:4:549 blocked for more than 120 seconds. [ 853.568693] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 853.635119] kworker/u:4 D ffff88013097b5d0 0 549 2 0x00000000 [ 853.695129] ffff880132773c40 0000000000000046 ffff880130790000 ffff880132773fd8 [ 853.758990] ffff880132773fd8 0000000000012500 ffff88013288a0b0 ffff880130790000 [ 853.822796] 0000000000000246 0000000000000040 ffff88013097b5c8 ffff880130790000 [ 853.886633] Call Trace: [ 853.907631] [<ffffffff8149dd25>] schedule+0x5a/0x5c [ 853.949670] [<ffffffff8149cc44>] __mutex_lock_common+0x220/0x351 [ 854.001225] [<ffffffff81304bd7>] ? device_resume+0x58/0x1c4 [ 854.049082] [<ffffffff81304bd7>] ? device_resume+0x58/0x1c4 [ 854.097011] [<ffffffff8149ce48>] mutex_lock_nested+0x2f/0x36 <-- here we wait for device_lock() [ 854.145591] [<ffffffff81304bd7>] device_resume+0x58/0x1c4 [ 854.192066] [<ffffffff81304d61>] async_resume+0x1e/0x45 [ 854.237019] [<ffffffff8104bc93>] async_run_entry_fn+0xc6/0x173 <-- ...while running in async context Provide a 'scsi_sd_probe_domain' so that async probe actions actions can be flushed without regard for the state of PM, and allow for the resume path to handle devices that have transitioned from SDEV_QUIESCE to SDEV_DEL prior to resume. Acked-by: Alan Stern <stern@rowland.harvard.edu> [alan: uplevel scsi_sd_probe_domain, clarify scsi_device_resume] Signed-off-by: Dan Williams <dan.j.williams@intel.com> [jejb: remove unneeded config guards in include file] Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2012-03-23 00:05:11 +00:00
void scsi_device_resume(struct scsi_device *sdev)
{
[SCSI] sd: limit the scope of the async probe domain sd injects and synchronizes probe work on the global kernel-wide domain. This runs into conflict with PM that wants to perform resume actions in async context: [ 494.237079] INFO: task kworker/u:3:554 blocked for more than 120 seconds. [ 494.294396] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 494.360809] kworker/u:3 D 0000000000000000 0 554 2 0x00000000 [ 494.420739] ffff88012e4d3af0 0000000000000046 ffff88013200c160 ffff88012e4d3fd8 [ 494.484392] ffff88012e4d3fd8 0000000000012500 ffff8801394ea0b0 ffff88013200c160 [ 494.548038] ffff88012e4d3ae0 00000000000001e3 ffffffff81a249e0 ffff8801321c5398 [ 494.611685] Call Trace: [ 494.632649] [<ffffffff8149dd25>] schedule+0x5a/0x5c [ 494.674687] [<ffffffff8104b968>] async_synchronize_cookie_domain+0xb6/0x112 [ 494.734177] [<ffffffff810461ff>] ? __init_waitqueue_head+0x50/0x50 [ 494.787134] [<ffffffff8131a224>] ? scsi_remove_target+0x48/0x48 [ 494.837900] [<ffffffff8104b9d9>] async_synchronize_cookie+0x15/0x17 [ 494.891567] [<ffffffff8104ba49>] async_synchronize_full+0x54/0x70 <-- here we wait for async contexts to complete [ 494.943783] [<ffffffff8104b9f5>] ? async_synchronize_full_domain+0x1a/0x1a [ 495.002547] [<ffffffffa00114b1>] sd_remove+0x2c/0xa2 [sd_mod] [ 495.051861] [<ffffffff812fe94f>] __device_release_driver+0x86/0xcf [ 495.104807] [<ffffffff812fe9bd>] device_release_driver+0x25/0x32 <-- here we take device_lock() [ 853.511341] INFO: task kworker/u:4:549 blocked for more than 120 seconds. [ 853.568693] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 853.635119] kworker/u:4 D ffff88013097b5d0 0 549 2 0x00000000 [ 853.695129] ffff880132773c40 0000000000000046 ffff880130790000 ffff880132773fd8 [ 853.758990] ffff880132773fd8 0000000000012500 ffff88013288a0b0 ffff880130790000 [ 853.822796] 0000000000000246 0000000000000040 ffff88013097b5c8 ffff880130790000 [ 853.886633] Call Trace: [ 853.907631] [<ffffffff8149dd25>] schedule+0x5a/0x5c [ 853.949670] [<ffffffff8149cc44>] __mutex_lock_common+0x220/0x351 [ 854.001225] [<ffffffff81304bd7>] ? device_resume+0x58/0x1c4 [ 854.049082] [<ffffffff81304bd7>] ? device_resume+0x58/0x1c4 [ 854.097011] [<ffffffff8149ce48>] mutex_lock_nested+0x2f/0x36 <-- here we wait for device_lock() [ 854.145591] [<ffffffff81304bd7>] device_resume+0x58/0x1c4 [ 854.192066] [<ffffffff81304d61>] async_resume+0x1e/0x45 [ 854.237019] [<ffffffff8104bc93>] async_run_entry_fn+0xc6/0x173 <-- ...while running in async context Provide a 'scsi_sd_probe_domain' so that async probe actions actions can be flushed without regard for the state of PM, and allow for the resume path to handle devices that have transitioned from SDEV_QUIESCE to SDEV_DEL prior to resume. Acked-by: Alan Stern <stern@rowland.harvard.edu> [alan: uplevel scsi_sd_probe_domain, clarify scsi_device_resume] Signed-off-by: Dan Williams <dan.j.williams@intel.com> [jejb: remove unneeded config guards in include file] Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2012-03-23 00:05:11 +00:00
/* check if the device state was mutated prior to resume, and if
* so assume the state is being managed elsewhere (for example
* device deleted during suspend)
*/
if (sdev->sdev_state != SDEV_QUIESCE ||
scsi_device_set_state(sdev, SDEV_RUNNING))
return;
scsi_run_queue(sdev->request_queue);
}
EXPORT_SYMBOL(scsi_device_resume);
static void
device_quiesce_fn(struct scsi_device *sdev, void *data)
{
scsi_device_quiesce(sdev);
}
void
scsi_target_quiesce(struct scsi_target *starget)
{
starget_for_each_device(starget, NULL, device_quiesce_fn);
}
EXPORT_SYMBOL(scsi_target_quiesce);
static void
device_resume_fn(struct scsi_device *sdev, void *data)
{
scsi_device_resume(sdev);
}
void
scsi_target_resume(struct scsi_target *starget)
{
starget_for_each_device(starget, NULL, device_resume_fn);
}
EXPORT_SYMBOL(scsi_target_resume);
/**
* scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
* @sdev: device to block
*
* Block request made by scsi lld's to temporarily stop all
* scsi commands on the specified device. May sleep.
*
* Returns zero if successful or error if not
*
* Notes:
* This routine transitions the device to the SDEV_BLOCK state
* (which must be a legal transition). When the device is in this
* state, all commands are deferred until the scsi lld reenables
* the device with scsi_device_unblock or device_block_tmo fires.
*
* To do: avoid that scsi_send_eh_cmnd() calls queuecommand() after
* scsi_internal_device_block() has blocked a SCSI device and also
* remove the rport mutex lock and unlock calls from srp_queuecommand().
*/
int
scsi_internal_device_block(struct scsi_device *sdev)
{
struct request_queue *q = sdev->request_queue;
unsigned long flags;
int err = 0;
err = scsi_device_set_state(sdev, SDEV_BLOCK);
if (err) {
err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
if (err)
return err;
}
/*
* The device has transitioned to SDEV_BLOCK. Stop the
* block layer from calling the midlayer with this device's
* request queue.
*/
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (q->mq_ops) {
blk_mq_quiesce_queue(q);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
} else {
spin_lock_irqsave(q->queue_lock, flags);
blk_stop_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
scsi_wait_for_queuecommand(sdev);
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
}
return 0;
}
EXPORT_SYMBOL_GPL(scsi_internal_device_block);
/**
* scsi_internal_device_unblock - resume a device after a block request
* @sdev: device to resume
* @new_state: state to set devices to after unblocking
*
* Called by scsi lld's or the midlayer to restart the device queue
* for the previously suspended scsi device. Called from interrupt or
* normal process context.
*
* Returns zero if successful or error if not.
*
* Notes:
* This routine transitions the device to the SDEV_RUNNING state
* or to one of the offline states (which must be a legal transition)
* allowing the midlayer to goose the queue for this device.
*/
int
scsi_internal_device_unblock(struct scsi_device *sdev,
enum scsi_device_state new_state)
{
struct request_queue *q = sdev->request_queue;
unsigned long flags;
/*
* Try to transition the scsi device to SDEV_RUNNING or one of the
* offlined states and goose the device queue if successful.
*/
if ((sdev->sdev_state == SDEV_BLOCK) ||
(sdev->sdev_state == SDEV_TRANSPORT_OFFLINE))
sdev->sdev_state = new_state;
else if (sdev->sdev_state == SDEV_CREATED_BLOCK) {
if (new_state == SDEV_TRANSPORT_OFFLINE ||
new_state == SDEV_OFFLINE)
sdev->sdev_state = new_state;
else
sdev->sdev_state = SDEV_CREATED;
} else if (sdev->sdev_state != SDEV_CANCEL &&
sdev->sdev_state != SDEV_OFFLINE)
return -EINVAL;
scsi: add support for a blk-mq based I/O path. This patch adds support for an alternate I/O path in the scsi midlayer which uses the blk-mq infrastructure instead of the legacy request code. Use of blk-mq is fully transparent to drivers, although for now a host template field is provided to opt out of blk-mq usage in case any unforseen incompatibilities arise. In general replacing the legacy request code with blk-mq is a simple and mostly mechanical transformation. The biggest exception is the new code that deals with the fact the I/O submissions in blk-mq must happen from process context, which slightly complicates the I/O completion handler. The second biggest differences is that blk-mq is build around the concept of preallocated requests that also include driver specific data, which in SCSI context means the scsi_cmnd structure. This completely avoids dynamic memory allocations for the fast path through I/O submission. Due the preallocated requests the MQ code path exclusively uses the host-wide shared tag allocator instead of a per-LUN one. This only affects drivers actually using the block layer provided tag allocator instead of their own. Unlike the old path blk-mq always provides a tag, although drivers don't have to use it. For now the blk-mq path is disable by defauly and must be enabled using the "use_blk_mq" module parameter. Once the remaining work in the block layer to make blk-mq more suitable for slow devices is complete I hope to make it the default and eventually even remove the old code path. Based on the earlier scsi-mq prototype by Nicholas Bellinger. Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and various sugestions and code contributions. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Webb Scales <webbnh@hp.com> Acked-by: Jens Axboe <axboe@kernel.dk> Tested-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Robert Elliott <elliott@hp.com>
2014-01-17 11:06:53 +00:00
if (q->mq_ops) {
blk_mq_start_stopped_hw_queues(q, false);
} else {
spin_lock_irqsave(q->queue_lock, flags);
blk_start_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
return 0;
}
EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
static void
device_block(struct scsi_device *sdev, void *data)
{
scsi_internal_device_block(sdev);
}
static int
target_block(struct device *dev, void *data)
{
if (scsi_is_target_device(dev))
starget_for_each_device(to_scsi_target(dev), NULL,
device_block);
return 0;
}
void
scsi_target_block(struct device *dev)
{
if (scsi_is_target_device(dev))
starget_for_each_device(to_scsi_target(dev), NULL,
device_block);
else
device_for_each_child(dev, NULL, target_block);
}
EXPORT_SYMBOL_GPL(scsi_target_block);
static void
device_unblock(struct scsi_device *sdev, void *data)
{
scsi_internal_device_unblock(sdev, *(enum scsi_device_state *)data);
}
static int
target_unblock(struct device *dev, void *data)
{
if (scsi_is_target_device(dev))
starget_for_each_device(to_scsi_target(dev), data,
device_unblock);
return 0;
}
void
scsi_target_unblock(struct device *dev, enum scsi_device_state new_state)
{
if (scsi_is_target_device(dev))
starget_for_each_device(to_scsi_target(dev), &new_state,
device_unblock);
else
device_for_each_child(dev, &new_state, target_unblock);
}
EXPORT_SYMBOL_GPL(scsi_target_unblock);
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
/**
* scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
* @sgl: scatter-gather list
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
* @sg_count: number of segments in sg
* @offset: offset in bytes into sg, on return offset into the mapped area
* @len: bytes to map, on return number of bytes mapped
*
* Returns virtual address of the start of the mapped page
*/
void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
size_t *offset, size_t *len)
{
int i;
size_t sg_len = 0, len_complete = 0;
struct scatterlist *sg;
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
struct page *page;
WARN_ON(!irqs_disabled());
for_each_sg(sgl, sg, sg_count, i) {
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
len_complete = sg_len; /* Complete sg-entries */
sg_len += sg->length;
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
if (sg_len > *offset)
break;
}
if (unlikely(i == sg_count)) {
printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
"elements %d\n",
__func__, sg_len, *offset, sg_count);
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
WARN_ON(1);
return NULL;
}
/* Offset starting from the beginning of first page in this sg-entry */
*offset = *offset - len_complete + sg->offset;
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
/* Assumption: contiguous pages can be accessed as "page + i" */
page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
*offset &= ~PAGE_MASK;
/* Bytes in this sg-entry from *offset to the end of the page */
sg_len = PAGE_SIZE - *offset;
if (*len > sg_len)
*len = sg_len;
return kmap_atomic(page);
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
}
EXPORT_SYMBOL(scsi_kmap_atomic_sg);
/**
* scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
* @virt: virtual address to be unmapped
*/
void scsi_kunmap_atomic_sg(void *virt)
{
kunmap_atomic(virt);
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
}
EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
void sdev_disable_disk_events(struct scsi_device *sdev)
{
atomic_inc(&sdev->disk_events_disable_depth);
}
EXPORT_SYMBOL(sdev_disable_disk_events);
void sdev_enable_disk_events(struct scsi_device *sdev)
{
if (WARN_ON_ONCE(atomic_read(&sdev->disk_events_disable_depth) <= 0))
return;
atomic_dec(&sdev->disk_events_disable_depth);
}
EXPORT_SYMBOL(sdev_enable_disk_events);
/**
* scsi_vpd_lun_id - return a unique device identification
* @sdev: SCSI device
* @id: buffer for the identification
* @id_len: length of the buffer
*
* Copies a unique device identification into @id based
* on the information in the VPD page 0x83 of the device.
* The string will be formatted as a SCSI name string.
*
* Returns the length of the identification or error on failure.
* If the identifier is longer than the supplied buffer the actual
* identifier length is returned and the buffer is not zero-padded.
*/
int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
{
u8 cur_id_type = 0xff;
u8 cur_id_size = 0;
unsigned char *d, *cur_id_str;
unsigned char __rcu *vpd_pg83;
int id_size = -EINVAL;
rcu_read_lock();
vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
if (!vpd_pg83) {
rcu_read_unlock();
return -ENXIO;
}
/*
* Look for the correct descriptor.
* Order of preference for lun descriptor:
* - SCSI name string
* - NAA IEEE Registered Extended
* - EUI-64 based 16-byte
* - EUI-64 based 12-byte
* - NAA IEEE Registered
* - NAA IEEE Extended
* - T10 Vendor ID
* as longer descriptors reduce the likelyhood
* of identification clashes.
*/
/* The id string must be at least 20 bytes + terminating NULL byte */
if (id_len < 21) {
rcu_read_unlock();
return -EINVAL;
}
memset(id, 0, id_len);
d = vpd_pg83 + 4;
while (d < vpd_pg83 + sdev->vpd_pg83_len) {
/* Skip designators not referring to the LUN */
if ((d[1] & 0x30) != 0x00)
goto next_desig;
switch (d[1] & 0xf) {
case 0x1:
/* T10 Vendor ID */
if (cur_id_size > d[3])
break;
/* Prefer anything */
if (cur_id_type > 0x01 && cur_id_type != 0xff)
break;
cur_id_size = d[3];
if (cur_id_size + 4 > id_len)
cur_id_size = id_len - 4;
cur_id_str = d + 4;
cur_id_type = d[1] & 0xf;
id_size = snprintf(id, id_len, "t10.%*pE",
cur_id_size, cur_id_str);
break;
case 0x2:
/* EUI-64 */
if (cur_id_size > d[3])
break;
/* Prefer NAA IEEE Registered Extended */
if (cur_id_type == 0x3 &&
cur_id_size == d[3])
break;
cur_id_size = d[3];
cur_id_str = d + 4;
cur_id_type = d[1] & 0xf;
switch (cur_id_size) {
case 8:
id_size = snprintf(id, id_len,
"eui.%8phN",
cur_id_str);
break;
case 12:
id_size = snprintf(id, id_len,
"eui.%12phN",
cur_id_str);
break;
case 16:
id_size = snprintf(id, id_len,
"eui.%16phN",
cur_id_str);
break;
default:
cur_id_size = 0;
break;
}
break;
case 0x3:
/* NAA */
if (cur_id_size > d[3])
break;
cur_id_size = d[3];
cur_id_str = d + 4;
cur_id_type = d[1] & 0xf;
switch (cur_id_size) {
case 8:
id_size = snprintf(id, id_len,
"naa.%8phN",
cur_id_str);
break;
case 16:
id_size = snprintf(id, id_len,
"naa.%16phN",
cur_id_str);
break;
default:
cur_id_size = 0;
break;
}
break;
case 0x8:
/* SCSI name string */
if (cur_id_size + 4 > d[3])
break;
/* Prefer others for truncated descriptor */
if (cur_id_size && d[3] > id_len)
break;
cur_id_size = id_size = d[3];
cur_id_str = d + 4;
cur_id_type = d[1] & 0xf;
if (cur_id_size >= id_len)
cur_id_size = id_len - 1;
memcpy(id, cur_id_str, cur_id_size);
/* Decrease priority for truncated descriptor */
if (cur_id_size != id_size)
cur_id_size = 6;
break;
default:
break;
}
next_desig:
d += d[3] + 4;
}
rcu_read_unlock();
return id_size;
}
EXPORT_SYMBOL(scsi_vpd_lun_id);
/*
* scsi_vpd_tpg_id - return a target port group identifier
* @sdev: SCSI device
*
* Returns the Target Port Group identifier from the information
* froom VPD page 0x83 of the device.
*
* Returns the identifier or error on failure.
*/
int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
{
unsigned char *d;
unsigned char __rcu *vpd_pg83;
int group_id = -EAGAIN, rel_port = -1;
rcu_read_lock();
vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
if (!vpd_pg83) {
rcu_read_unlock();
return -ENXIO;
}
d = sdev->vpd_pg83 + 4;
while (d < sdev->vpd_pg83 + sdev->vpd_pg83_len) {
switch (d[1] & 0xf) {
case 0x4:
/* Relative target port */
rel_port = get_unaligned_be16(&d[6]);
break;
case 0x5:
/* Target port group */
group_id = get_unaligned_be16(&d[6]);
break;
default:
break;
}
d += d[3] + 4;
}
rcu_read_unlock();
if (group_id >= 0 && rel_id && rel_port != -1)
*rel_id = rel_port;
return group_id;
}
EXPORT_SYMBOL(scsi_vpd_tpg_id);