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scsi: target: core: Break up target_submit_cmd_map_sgls()

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This breaks up target_submit_cmd_map_sgls() into 3 helpers:

 - target_init_cmd(): Do the basic general setup and get a refcount to the
   session to make sure the caller can execute the cmd.

 - target_submit_prep(): Do the mapping, cdb processing and get a ref to
   the LUN.

 - target_submit(): Pass the cmd to LIO core for execution.

The above functions must be used by drivers that either:

 1. Rely on LIO for session shutdown synchronization by calling
    target_stop_session().

 2. Need to map sgls.

When the next patches are applied then simple drivers that do not need the
extra functionality above can use target_submit_cmd() and not worry about
failures being returned and how to handle them, since many drivers were
getting this wrong and would have hit refcount bugs.

Also, by breaking target_submit_cmd_map_sgls() up into these 3 helper
functions, we can allow the later patches to do the init/prep from
interrupt context and then do the submission from a workqueue.

Link: https://lore.kernel.org/r/20210227170006.5077-5-michael.christie@oracle.com
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Nilesh Javali <njavali@marvell.com>
Cc: Michael Cyr <mikecyr@linux.ibm.com>
Cc: Chris Boot <bootc@bootc.net>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Mike Christie 2021-02-27 10:59:45 -06:00 committed by Martin K. Petersen
parent a78b713618
commit 750a1d93f9
2 changed files with 198 additions and 111 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

301
drivers/target/target_core_transport.c
View File

@ -1572,9 +1572,190 @@ transport_generic_map_mem_to_cmd(struct se_cmd *cmd, struct scatterlist *sgl,
return 0;
}
/**
* target_init_cmd - initialize se_cmd
* @se_cmd: command descriptor to init
* @se_sess: associated se_sess for endpoint
* @sense: pointer to SCSI sense buffer
* @unpacked_lun: unpacked LUN to reference for struct se_lun
* @data_length: fabric expected data transfer length
* @task_attr: SAM task attribute
* @data_dir: DMA data direction
* @flags: flags for command submission from target_sc_flags_tables
*
* Task tags are supported if the caller has set @se_cmd->tag.
*
* Returns:
* - less than zero to signal active I/O shutdown failure.
* - zero on success.
*
* If the fabric driver calls target_stop_session, then it must check the
* return code and handle failures. This will never fail for other drivers,
* and the return code can be ignored.
*/
int target_init_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,
unsigned char *sense, u64 unpacked_lun,
u32 data_length, int task_attr, int data_dir, int flags)
{
struct se_portal_group *se_tpg;
se_tpg = se_sess->se_tpg;
BUG_ON(!se_tpg);
BUG_ON(se_cmd->se_tfo || se_cmd->se_sess);
if (flags & TARGET_SCF_USE_CPUID)
se_cmd->se_cmd_flags |= SCF_USE_CPUID;
/*
* Signal bidirectional data payloads to target-core
*/
if (flags & TARGET_SCF_BIDI_OP)
se_cmd->se_cmd_flags |= SCF_BIDI;
if (flags & TARGET_SCF_UNKNOWN_SIZE)
se_cmd->unknown_data_length = 1;
/*
* Initialize se_cmd for target operation. From this point
* exceptions are handled by sending exception status via
* target_core_fabric_ops->queue_status() callback
*/
__target_init_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess, data_length,
data_dir, task_attr, sense, unpacked_lun);
/*
* Obtain struct se_cmd->cmd_kref reference. A second kref_get here is
* necessary for fabrics using TARGET_SCF_ACK_KREF that expect a second
* kref_put() to happen during fabric packet acknowledgement.
*/
return target_get_sess_cmd(se_cmd, flags & TARGET_SCF_ACK_KREF);
}
EXPORT_SYMBOL_GPL(target_init_cmd);
/**
* target_submit_prep - prepare cmd for submission
* @se_cmd: command descriptor to prep
* @cdb: pointer to SCSI CDB
* @sgl: struct scatterlist memory for unidirectional mapping
* @sgl_count: scatterlist count for unidirectional mapping
* @sgl_bidi: struct scatterlist memory for bidirectional READ mapping
* @sgl_bidi_count: scatterlist count for bidirectional READ mapping
* @sgl_prot: struct scatterlist memory protection information
* @sgl_prot_count: scatterlist count for protection information
*
* Returns:
* - less than zero to signal failure.
* - zero on success.
* If failure is returned, lio will the callers queue_status to complete
* the cmd.
*/
int target_submit_prep(struct se_cmd *se_cmd, unsigned char *cdb,
struct scatterlist *sgl, u32 sgl_count,
struct scatterlist *sgl_bidi, u32 sgl_bidi_count,
struct scatterlist *sgl_prot, u32 sgl_prot_count)
{
sense_reason_t rc;
rc = target_cmd_init_cdb(se_cmd, cdb);
if (rc)
goto send_cc_direct;
/*
* Locate se_lun pointer and attach it to struct se_cmd
*/
rc = transport_lookup_cmd_lun(se_cmd);
if (rc)
goto send_cc_direct;
rc = target_cmd_parse_cdb(se_cmd);
if (rc != 0)
goto generic_fail;
/*
* Save pointers for SGLs containing protection information,
* if present.
*/
if (sgl_prot_count) {
se_cmd->t_prot_sg = sgl_prot;
se_cmd->t_prot_nents = sgl_prot_count;
se_cmd->se_cmd_flags |= SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC;
}
/*
* When a non zero sgl_count has been passed perform SGL passthrough
* mapping for pre-allocated fabric memory instead of having target
* core perform an internal SGL allocation..
*/
if (sgl_count != 0) {
BUG_ON(!sgl);
rc = transport_generic_map_mem_to_cmd(se_cmd, sgl, sgl_count,
sgl_bidi, sgl_bidi_count);
if (rc != 0)
goto generic_fail;
}
return 0;
send_cc_direct:
transport_send_check_condition_and_sense(se_cmd, rc, 0);
target_put_sess_cmd(se_cmd);
return -EIO;
generic_fail:
transport_generic_request_failure(se_cmd, rc);
return -EIO;
}
EXPORT_SYMBOL_GPL(target_submit_prep);
/**
* target_submit - perform final initialization and submit cmd to LIO core
* @se_cmd: command descriptor to submit
*
* target_submit_prep must have been called on the cmd, and this must be
* called from process context.
*/
void target_submit(struct se_cmd *se_cmd)
{
struct scatterlist *sgl = se_cmd->t_data_sg;
unsigned char *buf = NULL;
might_sleep();
if (se_cmd->t_data_nents != 0) {
BUG_ON(!sgl);
/*
* A work-around for tcm_loop as some userspace code via
* scsi-generic do not memset their associated read buffers,
* so go ahead and do that here for type non-data CDBs. Also
* note that this is currently guaranteed to be a single SGL
* for this case by target core in target_setup_cmd_from_cdb()
* -> transport_generic_cmd_sequencer().
*/
if (!(se_cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) &&
se_cmd->data_direction == DMA_FROM_DEVICE) {
if (sgl)
buf = kmap(sg_page(sgl)) + sgl->offset;
if (buf) {
memset(buf, 0, sgl->length);
kunmap(sg_page(sgl));
}
}
}
/*
* Check if we need to delay processing because of ALUA
* Active/NonOptimized primary access state..
*/
core_alua_check_nonop_delay(se_cmd);
transport_handle_cdb_direct(se_cmd);
}
EXPORT_SYMBOL_GPL(target_submit);
/**
* target_submit_cmd_map_sgls - lookup unpacked lun and submit uninitialized
* se_cmd + use pre-allocated SGL memory.
* se_cmd + use pre-allocated SGL memory.
*
* @se_cmd: command descriptor to submit
* @se_sess: associated se_sess for endpoint
@ -1608,120 +1789,18 @@ int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess
struct scatterlist *sgl_bidi, u32 sgl_bidi_count,
struct scatterlist *sgl_prot, u32 sgl_prot_count)
{
struct se_portal_group *se_tpg;
sense_reason_t rc;
int ret;
int rc;
might_sleep();
rc = target_init_cmd(se_cmd, se_sess, sense, unpacked_lun,
data_length, task_attr, data_dir, flags);
if (rc < 0)
return rc;
se_tpg = se_sess->se_tpg;
BUG_ON(!se_tpg);
BUG_ON(se_cmd->se_tfo || se_cmd->se_sess);
if (flags & TARGET_SCF_USE_CPUID)
se_cmd->se_cmd_flags |= SCF_USE_CPUID;
/*
* Initialize se_cmd for target operation. From this point
* exceptions are handled by sending exception status via
* target_core_fabric_ops->queue_status() callback
*/
__target_init_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess,
data_length, data_dir, task_attr, sense,
unpacked_lun);
if (flags & TARGET_SCF_UNKNOWN_SIZE)
se_cmd->unknown_data_length = 1;
/*
* Obtain struct se_cmd->cmd_kref reference. A second kref_get here is
* necessary for fabrics using TARGET_SCF_ACK_KREF that expect a second
* kref_put() to happen during fabric packet acknowledgement.
*/
ret = target_get_sess_cmd(se_cmd, flags & TARGET_SCF_ACK_KREF);
if (ret)
return ret;
/*
* Signal bidirectional data payloads to target-core
*/
if (flags & TARGET_SCF_BIDI_OP)
se_cmd->se_cmd_flags |= SCF_BIDI;
rc = target_cmd_init_cdb(se_cmd, cdb);
if (rc) {
transport_send_check_condition_and_sense(se_cmd, rc, 0);
target_put_sess_cmd(se_cmd);
if (target_submit_prep(se_cmd, cdb, sgl, sgl_count, sgl_bidi,
sgl_bidi_count, sgl_prot, sgl_prot_count))
return 0;
}
/*
* Locate se_lun pointer and attach it to struct se_cmd
*/
rc = transport_lookup_cmd_lun(se_cmd);
if (rc) {
transport_send_check_condition_and_sense(se_cmd, rc, 0);
target_put_sess_cmd(se_cmd);
return 0;
}
rc = target_cmd_parse_cdb(se_cmd);
if (rc != 0) {
transport_generic_request_failure(se_cmd, rc);
return 0;
}
/*
* Save pointers for SGLs containing protection information,
* if present.
*/
if (sgl_prot_count) {
se_cmd->t_prot_sg = sgl_prot;
se_cmd->t_prot_nents = sgl_prot_count;
se_cmd->se_cmd_flags |= SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC;
}
/*
* When a non zero sgl_count has been passed perform SGL passthrough
* mapping for pre-allocated fabric memory instead of having target
* core perform an internal SGL allocation..
*/
if (sgl_count != 0) {
BUG_ON(!sgl);
/*
* A work-around for tcm_loop as some userspace code via
* scsi-generic do not memset their associated read buffers,
* so go ahead and do that here for type non-data CDBs. Also
* note that this is currently guaranteed to be a single SGL
* for this case by target core in target_setup_cmd_from_cdb()
* -> transport_generic_cmd_sequencer().
*/
if (!(se_cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) &&
se_cmd->data_direction == DMA_FROM_DEVICE) {
unsigned char *buf = NULL;
if (sgl)
buf = kmap(sg_page(sgl)) + sgl->offset;
if (buf) {
memset(buf, 0, sgl->length);
kunmap(sg_page(sgl));
}
}
rc = transport_generic_map_mem_to_cmd(se_cmd, sgl, sgl_count,
sgl_bidi, sgl_bidi_count);
if (rc != 0) {
transport_generic_request_failure(se_cmd, rc);
return 0;
}
}
/*
* Check if we need to delay processing because of ALUA
* Active/NonOptimized primary access state..
*/
core_alua_check_nonop_delay(se_cmd);
transport_handle_cdb_direct(se_cmd);
target_submit(se_cmd);
return 0;
}
EXPORT_SYMBOL(target_submit_cmd_map_sgls);

8
include/target/target_core_fabric.h
View File

@ -151,6 +151,14 @@ void transport_deregister_session(struct se_session *);
void __target_init_cmd(struct se_cmd *,
const struct target_core_fabric_ops *,
struct se_session *, u32, int, int, unsigned char *, u64);
int target_init_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,
unsigned char *sense, u64 unpacked_lun, u32 data_length,
int task_attr, int data_dir, int flags);
int target_submit_prep(struct se_cmd *se_cmd, unsigned char *cdb,
struct scatterlist *sgl, u32 sgl_count,
struct scatterlist *sgl_bidi, u32 sgl_bidi_count,
struct scatterlist *sgl_prot, u32 sgl_prot_count);
void target_submit(struct se_cmd *se_cmd);
sense_reason_t transport_lookup_cmd_lun(struct se_cmd *);
sense_reason_t target_cmd_init_cdb(struct se_cmd *, unsigned char *);
sense_reason_t target_cmd_parse_cdb(struct se_cmd *);