forked from Minki/linux
fd782a4a99
get_request is now expected to be holding on to queue_lock, with interrupts disabled, when it returns NULL; but one path forgot that, causing all kinds of nastiness under swap load - badness backtraces, strange failures, BUGs. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
3602 lines
91 KiB
C
3602 lines
91 KiB
C
/*
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* linux/drivers/block/ll_rw_blk.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright (C) 1994, Karl Keyte: Added support for disk statistics
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* Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
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* Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
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* kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> - July2000
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* bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
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*/
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/*
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* This handles all read/write requests to block devices
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*/
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#include <linux/config.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/backing-dev.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/highmem.h>
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#include <linux/mm.h>
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#include <linux/kernel_stat.h>
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#include <linux/string.h>
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#include <linux/init.h>
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#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
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#include <linux/completion.h>
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#include <linux/slab.h>
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#include <linux/swap.h>
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#include <linux/writeback.h>
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#include <linux/blkdev.h>
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/*
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* for max sense size
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*/
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#include <scsi/scsi_cmnd.h>
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static void blk_unplug_work(void *data);
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static void blk_unplug_timeout(unsigned long data);
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static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io);
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/*
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* For the allocated request tables
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*/
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static kmem_cache_t *request_cachep;
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/*
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* For queue allocation
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*/
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static kmem_cache_t *requestq_cachep;
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/*
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* For io context allocations
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*/
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static kmem_cache_t *iocontext_cachep;
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static wait_queue_head_t congestion_wqh[2] = {
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__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
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__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
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};
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/*
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* Controlling structure to kblockd
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*/
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static struct workqueue_struct *kblockd_workqueue;
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unsigned long blk_max_low_pfn, blk_max_pfn;
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EXPORT_SYMBOL(blk_max_low_pfn);
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EXPORT_SYMBOL(blk_max_pfn);
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/* Amount of time in which a process may batch requests */
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#define BLK_BATCH_TIME (HZ/50UL)
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/* Number of requests a "batching" process may submit */
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#define BLK_BATCH_REQ 32
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/*
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* Return the threshold (number of used requests) at which the queue is
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* considered to be congested. It include a little hysteresis to keep the
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* context switch rate down.
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*/
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static inline int queue_congestion_on_threshold(struct request_queue *q)
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{
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return q->nr_congestion_on;
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}
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/*
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* The threshold at which a queue is considered to be uncongested
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*/
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static inline int queue_congestion_off_threshold(struct request_queue *q)
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{
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return q->nr_congestion_off;
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}
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static void blk_queue_congestion_threshold(struct request_queue *q)
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{
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int nr;
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nr = q->nr_requests - (q->nr_requests / 8) + 1;
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if (nr > q->nr_requests)
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nr = q->nr_requests;
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q->nr_congestion_on = nr;
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nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
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if (nr < 1)
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nr = 1;
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q->nr_congestion_off = nr;
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}
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/*
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* A queue has just exitted congestion. Note this in the global counter of
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* congested queues, and wake up anyone who was waiting for requests to be
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* put back.
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*/
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static void clear_queue_congested(request_queue_t *q, int rw)
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{
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enum bdi_state bit;
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wait_queue_head_t *wqh = &congestion_wqh[rw];
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bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
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clear_bit(bit, &q->backing_dev_info.state);
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smp_mb__after_clear_bit();
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if (waitqueue_active(wqh))
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wake_up(wqh);
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}
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/*
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* A queue has just entered congestion. Flag that in the queue's VM-visible
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* state flags and increment the global gounter of congested queues.
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*/
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static void set_queue_congested(request_queue_t *q, int rw)
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{
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enum bdi_state bit;
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bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
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set_bit(bit, &q->backing_dev_info.state);
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}
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/**
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* blk_get_backing_dev_info - get the address of a queue's backing_dev_info
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* @bdev: device
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*
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* Locates the passed device's request queue and returns the address of its
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* backing_dev_info
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*
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* Will return NULL if the request queue cannot be located.
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*/
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struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
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{
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struct backing_dev_info *ret = NULL;
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request_queue_t *q = bdev_get_queue(bdev);
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if (q)
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ret = &q->backing_dev_info;
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return ret;
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}
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EXPORT_SYMBOL(blk_get_backing_dev_info);
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void blk_queue_activity_fn(request_queue_t *q, activity_fn *fn, void *data)
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{
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q->activity_fn = fn;
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q->activity_data = data;
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}
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EXPORT_SYMBOL(blk_queue_activity_fn);
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/**
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* blk_queue_prep_rq - set a prepare_request function for queue
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* @q: queue
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* @pfn: prepare_request function
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*
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* It's possible for a queue to register a prepare_request callback which
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* is invoked before the request is handed to the request_fn. The goal of
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* the function is to prepare a request for I/O, it can be used to build a
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* cdb from the request data for instance.
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*
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*/
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void blk_queue_prep_rq(request_queue_t *q, prep_rq_fn *pfn)
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{
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q->prep_rq_fn = pfn;
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}
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EXPORT_SYMBOL(blk_queue_prep_rq);
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/**
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* blk_queue_merge_bvec - set a merge_bvec function for queue
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* @q: queue
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* @mbfn: merge_bvec_fn
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*
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* Usually queues have static limitations on the max sectors or segments that
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* we can put in a request. Stacking drivers may have some settings that
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* are dynamic, and thus we have to query the queue whether it is ok to
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* add a new bio_vec to a bio at a given offset or not. If the block device
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* has such limitations, it needs to register a merge_bvec_fn to control
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* the size of bio's sent to it. Note that a block device *must* allow a
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* single page to be added to an empty bio. The block device driver may want
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* to use the bio_split() function to deal with these bio's. By default
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* no merge_bvec_fn is defined for a queue, and only the fixed limits are
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* honored.
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*/
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void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn)
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{
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q->merge_bvec_fn = mbfn;
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}
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EXPORT_SYMBOL(blk_queue_merge_bvec);
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/**
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* blk_queue_make_request - define an alternate make_request function for a device
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* @q: the request queue for the device to be affected
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* @mfn: the alternate make_request function
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*
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* Description:
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* The normal way for &struct bios to be passed to a device
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* driver is for them to be collected into requests on a request
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* queue, and then to allow the device driver to select requests
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* off that queue when it is ready. This works well for many block
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* devices. However some block devices (typically virtual devices
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* such as md or lvm) do not benefit from the processing on the
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* request queue, and are served best by having the requests passed
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* directly to them. This can be achieved by providing a function
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* to blk_queue_make_request().
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*
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* Caveat:
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* The driver that does this *must* be able to deal appropriately
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* with buffers in "highmemory". This can be accomplished by either calling
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* __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
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* blk_queue_bounce() to create a buffer in normal memory.
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**/
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void blk_queue_make_request(request_queue_t * q, make_request_fn * mfn)
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{
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/*
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* set defaults
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*/
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q->nr_requests = BLKDEV_MAX_RQ;
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q->max_phys_segments = MAX_PHYS_SEGMENTS;
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q->max_hw_segments = MAX_HW_SEGMENTS;
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q->make_request_fn = mfn;
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q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
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q->backing_dev_info.state = 0;
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q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
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blk_queue_max_sectors(q, MAX_SECTORS);
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blk_queue_hardsect_size(q, 512);
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blk_queue_dma_alignment(q, 511);
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blk_queue_congestion_threshold(q);
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q->nr_batching = BLK_BATCH_REQ;
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q->unplug_thresh = 4; /* hmm */
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q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */
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if (q->unplug_delay == 0)
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q->unplug_delay = 1;
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INIT_WORK(&q->unplug_work, blk_unplug_work, q);
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q->unplug_timer.function = blk_unplug_timeout;
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q->unplug_timer.data = (unsigned long)q;
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/*
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* by default assume old behaviour and bounce for any highmem page
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*/
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blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
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blk_queue_activity_fn(q, NULL, NULL);
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INIT_LIST_HEAD(&q->drain_list);
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}
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EXPORT_SYMBOL(blk_queue_make_request);
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static inline void rq_init(request_queue_t *q, struct request *rq)
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{
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INIT_LIST_HEAD(&rq->queuelist);
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rq->errors = 0;
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rq->rq_status = RQ_ACTIVE;
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rq->bio = rq->biotail = NULL;
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rq->ioprio = 0;
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rq->buffer = NULL;
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rq->ref_count = 1;
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rq->q = q;
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rq->waiting = NULL;
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rq->special = NULL;
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rq->data_len = 0;
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rq->data = NULL;
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rq->sense = NULL;
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rq->end_io = NULL;
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rq->end_io_data = NULL;
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}
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/**
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* blk_queue_ordered - does this queue support ordered writes
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* @q: the request queue
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* @flag: see below
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*
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* Description:
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* For journalled file systems, doing ordered writes on a commit
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* block instead of explicitly doing wait_on_buffer (which is bad
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* for performance) can be a big win. Block drivers supporting this
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* feature should call this function and indicate so.
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*
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**/
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void blk_queue_ordered(request_queue_t *q, int flag)
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{
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switch (flag) {
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case QUEUE_ORDERED_NONE:
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if (q->flush_rq)
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kmem_cache_free(request_cachep, q->flush_rq);
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q->flush_rq = NULL;
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q->ordered = flag;
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break;
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case QUEUE_ORDERED_TAG:
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q->ordered = flag;
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break;
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case QUEUE_ORDERED_FLUSH:
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q->ordered = flag;
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if (!q->flush_rq)
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q->flush_rq = kmem_cache_alloc(request_cachep,
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GFP_KERNEL);
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break;
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default:
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printk("blk_queue_ordered: bad value %d\n", flag);
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break;
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}
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}
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EXPORT_SYMBOL(blk_queue_ordered);
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/**
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* blk_queue_issue_flush_fn - set function for issuing a flush
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* @q: the request queue
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* @iff: the function to be called issuing the flush
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*
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* Description:
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* If a driver supports issuing a flush command, the support is notified
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* to the block layer by defining it through this call.
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*
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**/
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void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff)
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{
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q->issue_flush_fn = iff;
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}
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EXPORT_SYMBOL(blk_queue_issue_flush_fn);
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/*
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* Cache flushing for ordered writes handling
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*/
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static void blk_pre_flush_end_io(struct request *flush_rq)
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{
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struct request *rq = flush_rq->end_io_data;
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request_queue_t *q = rq->q;
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rq->flags |= REQ_BAR_PREFLUSH;
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if (!flush_rq->errors)
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elv_requeue_request(q, rq);
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else {
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q->end_flush_fn(q, flush_rq);
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clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
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q->request_fn(q);
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}
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}
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static void blk_post_flush_end_io(struct request *flush_rq)
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{
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struct request *rq = flush_rq->end_io_data;
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request_queue_t *q = rq->q;
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rq->flags |= REQ_BAR_POSTFLUSH;
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q->end_flush_fn(q, flush_rq);
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clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
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q->request_fn(q);
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}
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struct request *blk_start_pre_flush(request_queue_t *q, struct request *rq)
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{
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struct request *flush_rq = q->flush_rq;
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BUG_ON(!blk_barrier_rq(rq));
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if (test_and_set_bit(QUEUE_FLAG_FLUSH, &q->queue_flags))
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return NULL;
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rq_init(q, flush_rq);
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flush_rq->elevator_private = NULL;
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flush_rq->flags = REQ_BAR_FLUSH;
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flush_rq->rq_disk = rq->rq_disk;
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flush_rq->rl = NULL;
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/*
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* prepare_flush returns 0 if no flush is needed, just mark both
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* pre and post flush as done in that case
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*/
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if (!q->prepare_flush_fn(q, flush_rq)) {
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rq->flags |= REQ_BAR_PREFLUSH | REQ_BAR_POSTFLUSH;
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clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
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return rq;
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}
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|
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/*
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* some drivers dequeue requests right away, some only after io
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* completion. make sure the request is dequeued.
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*/
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if (!list_empty(&rq->queuelist))
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blkdev_dequeue_request(rq);
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elv_deactivate_request(q, rq);
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|
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flush_rq->end_io_data = rq;
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flush_rq->end_io = blk_pre_flush_end_io;
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|
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__elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0);
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return flush_rq;
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}
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|
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static void blk_start_post_flush(request_queue_t *q, struct request *rq)
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{
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struct request *flush_rq = q->flush_rq;
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BUG_ON(!blk_barrier_rq(rq));
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|
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rq_init(q, flush_rq);
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flush_rq->elevator_private = NULL;
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flush_rq->flags = REQ_BAR_FLUSH;
|
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flush_rq->rq_disk = rq->rq_disk;
|
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flush_rq->rl = NULL;
|
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|
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if (q->prepare_flush_fn(q, flush_rq)) {
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flush_rq->end_io_data = rq;
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flush_rq->end_io = blk_post_flush_end_io;
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|
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__elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0);
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q->request_fn(q);
|
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}
|
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}
|
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|
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static inline int blk_check_end_barrier(request_queue_t *q, struct request *rq,
|
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int sectors)
|
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{
|
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if (sectors > rq->nr_sectors)
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sectors = rq->nr_sectors;
|
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|
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rq->nr_sectors -= sectors;
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return rq->nr_sectors;
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}
|
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|
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static int __blk_complete_barrier_rq(request_queue_t *q, struct request *rq,
|
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int sectors, int queue_locked)
|
|
{
|
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if (q->ordered != QUEUE_ORDERED_FLUSH)
|
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return 0;
|
|
if (!blk_fs_request(rq) || !blk_barrier_rq(rq))
|
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return 0;
|
|
if (blk_barrier_postflush(rq))
|
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return 0;
|
|
|
|
if (!blk_check_end_barrier(q, rq, sectors)) {
|
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unsigned long flags = 0;
|
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|
|
if (!queue_locked)
|
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spin_lock_irqsave(q->queue_lock, flags);
|
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|
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blk_start_post_flush(q, rq);
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|
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if (!queue_locked)
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spin_unlock_irqrestore(q->queue_lock, flags);
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}
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|
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return 1;
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}
|
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|
|
/**
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* blk_complete_barrier_rq - complete possible barrier request
|
|
* @q: the request queue for the device
|
|
* @rq: the request
|
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* @sectors: number of sectors to complete
|
|
*
|
|
* Description:
|
|
* Used in driver end_io handling to determine whether to postpone
|
|
* completion of a barrier request until a post flush has been done. This
|
|
* is the unlocked variant, used if the caller doesn't already hold the
|
|
* queue lock.
|
|
**/
|
|
int blk_complete_barrier_rq(request_queue_t *q, struct request *rq, int sectors)
|
|
{
|
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return __blk_complete_barrier_rq(q, rq, sectors, 0);
|
|
}
|
|
EXPORT_SYMBOL(blk_complete_barrier_rq);
|
|
|
|
/**
|
|
* blk_complete_barrier_rq_locked - complete possible barrier request
|
|
* @q: the request queue for the device
|
|
* @rq: the request
|
|
* @sectors: number of sectors to complete
|
|
*
|
|
* Description:
|
|
* See blk_complete_barrier_rq(). This variant must be used if the caller
|
|
* holds the queue lock.
|
|
**/
|
|
int blk_complete_barrier_rq_locked(request_queue_t *q, struct request *rq,
|
|
int sectors)
|
|
{
|
|
return __blk_complete_barrier_rq(q, rq, sectors, 1);
|
|
}
|
|
EXPORT_SYMBOL(blk_complete_barrier_rq_locked);
|
|
|
|
/**
|
|
* blk_queue_bounce_limit - set bounce buffer limit for queue
|
|
* @q: the request queue for the device
|
|
* @dma_addr: bus address limit
|
|
*
|
|
* Description:
|
|
* Different hardware can have different requirements as to what pages
|
|
* it can do I/O directly to. A low level driver can call
|
|
* blk_queue_bounce_limit to have lower memory pages allocated as bounce
|
|
* buffers for doing I/O to pages residing above @page. By default
|
|
* the block layer sets this to the highest numbered "low" memory page.
|
|
**/
|
|
void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr)
|
|
{
|
|
unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT;
|
|
|
|
/*
|
|
* set appropriate bounce gfp mask -- unfortunately we don't have a
|
|
* full 4GB zone, so we have to resort to low memory for any bounces.
|
|
* ISA has its own < 16MB zone.
|
|
*/
|
|
if (bounce_pfn < blk_max_low_pfn) {
|
|
BUG_ON(dma_addr < BLK_BOUNCE_ISA);
|
|
init_emergency_isa_pool();
|
|
q->bounce_gfp = GFP_NOIO | GFP_DMA;
|
|
} else
|
|
q->bounce_gfp = GFP_NOIO;
|
|
|
|
q->bounce_pfn = bounce_pfn;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_bounce_limit);
|
|
|
|
/**
|
|
* blk_queue_max_sectors - set max sectors for a request for this queue
|
|
* @q: the request queue for the device
|
|
* @max_sectors: max sectors in the usual 512b unit
|
|
*
|
|
* Description:
|
|
* Enables a low level driver to set an upper limit on the size of
|
|
* received requests.
|
|
**/
|
|
void blk_queue_max_sectors(request_queue_t *q, unsigned short max_sectors)
|
|
{
|
|
if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
|
|
max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
|
|
printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors);
|
|
}
|
|
|
|
q->max_sectors = q->max_hw_sectors = max_sectors;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_max_sectors);
|
|
|
|
/**
|
|
* blk_queue_max_phys_segments - set max phys segments for a request for this queue
|
|
* @q: the request queue for the device
|
|
* @max_segments: max number of segments
|
|
*
|
|
* Description:
|
|
* Enables a low level driver to set an upper limit on the number of
|
|
* physical data segments in a request. This would be the largest sized
|
|
* scatter list the driver could handle.
|
|
**/
|
|
void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments)
|
|
{
|
|
if (!max_segments) {
|
|
max_segments = 1;
|
|
printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
|
|
}
|
|
|
|
q->max_phys_segments = max_segments;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_max_phys_segments);
|
|
|
|
/**
|
|
* blk_queue_max_hw_segments - set max hw segments for a request for this queue
|
|
* @q: the request queue for the device
|
|
* @max_segments: max number of segments
|
|
*
|
|
* Description:
|
|
* Enables a low level driver to set an upper limit on the number of
|
|
* hw data segments in a request. This would be the largest number of
|
|
* address/length pairs the host adapter can actually give as once
|
|
* to the device.
|
|
**/
|
|
void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments)
|
|
{
|
|
if (!max_segments) {
|
|
max_segments = 1;
|
|
printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
|
|
}
|
|
|
|
q->max_hw_segments = max_segments;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_max_hw_segments);
|
|
|
|
/**
|
|
* blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
|
|
* @q: the request queue for the device
|
|
* @max_size: max size of segment in bytes
|
|
*
|
|
* Description:
|
|
* Enables a low level driver to set an upper limit on the size of a
|
|
* coalesced segment
|
|
**/
|
|
void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size)
|
|
{
|
|
if (max_size < PAGE_CACHE_SIZE) {
|
|
max_size = PAGE_CACHE_SIZE;
|
|
printk("%s: set to minimum %d\n", __FUNCTION__, max_size);
|
|
}
|
|
|
|
q->max_segment_size = max_size;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_max_segment_size);
|
|
|
|
/**
|
|
* blk_queue_hardsect_size - set hardware sector size for the queue
|
|
* @q: the request queue for the device
|
|
* @size: the hardware sector size, in bytes
|
|
*
|
|
* Description:
|
|
* This should typically be set to the lowest possible sector size
|
|
* that the hardware can operate on (possible without reverting to
|
|
* even internal read-modify-write operations). Usually the default
|
|
* of 512 covers most hardware.
|
|
**/
|
|
void blk_queue_hardsect_size(request_queue_t *q, unsigned short size)
|
|
{
|
|
q->hardsect_size = size;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_hardsect_size);
|
|
|
|
/*
|
|
* Returns the minimum that is _not_ zero, unless both are zero.
|
|
*/
|
|
#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
|
|
|
|
/**
|
|
* blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
|
|
* @t: the stacking driver (top)
|
|
* @b: the underlying device (bottom)
|
|
**/
|
|
void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b)
|
|
{
|
|
/* zero is "infinity" */
|
|
t->max_sectors = t->max_hw_sectors =
|
|
min_not_zero(t->max_sectors,b->max_sectors);
|
|
|
|
t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
|
|
t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
|
|
t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
|
|
t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_stack_limits);
|
|
|
|
/**
|
|
* blk_queue_segment_boundary - set boundary rules for segment merging
|
|
* @q: the request queue for the device
|
|
* @mask: the memory boundary mask
|
|
**/
|
|
void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask)
|
|
{
|
|
if (mask < PAGE_CACHE_SIZE - 1) {
|
|
mask = PAGE_CACHE_SIZE - 1;
|
|
printk("%s: set to minimum %lx\n", __FUNCTION__, mask);
|
|
}
|
|
|
|
q->seg_boundary_mask = mask;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_segment_boundary);
|
|
|
|
/**
|
|
* blk_queue_dma_alignment - set dma length and memory alignment
|
|
* @q: the request queue for the device
|
|
* @mask: alignment mask
|
|
*
|
|
* description:
|
|
* set required memory and length aligment for direct dma transactions.
|
|
* this is used when buiding direct io requests for the queue.
|
|
*
|
|
**/
|
|
void blk_queue_dma_alignment(request_queue_t *q, int mask)
|
|
{
|
|
q->dma_alignment = mask;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_dma_alignment);
|
|
|
|
/**
|
|
* blk_queue_find_tag - find a request by its tag and queue
|
|
*
|
|
* @q: The request queue for the device
|
|
* @tag: The tag of the request
|
|
*
|
|
* Notes:
|
|
* Should be used when a device returns a tag and you want to match
|
|
* it with a request.
|
|
*
|
|
* no locks need be held.
|
|
**/
|
|
struct request *blk_queue_find_tag(request_queue_t *q, int tag)
|
|
{
|
|
struct blk_queue_tag *bqt = q->queue_tags;
|
|
|
|
if (unlikely(bqt == NULL || tag >= bqt->max_depth))
|
|
return NULL;
|
|
|
|
return bqt->tag_index[tag];
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_find_tag);
|
|
|
|
/**
|
|
* __blk_queue_free_tags - release tag maintenance info
|
|
* @q: the request queue for the device
|
|
*
|
|
* Notes:
|
|
* blk_cleanup_queue() will take care of calling this function, if tagging
|
|
* has been used. So there's no need to call this directly.
|
|
**/
|
|
static void __blk_queue_free_tags(request_queue_t *q)
|
|
{
|
|
struct blk_queue_tag *bqt = q->queue_tags;
|
|
|
|
if (!bqt)
|
|
return;
|
|
|
|
if (atomic_dec_and_test(&bqt->refcnt)) {
|
|
BUG_ON(bqt->busy);
|
|
BUG_ON(!list_empty(&bqt->busy_list));
|
|
|
|
kfree(bqt->tag_index);
|
|
bqt->tag_index = NULL;
|
|
|
|
kfree(bqt->tag_map);
|
|
bqt->tag_map = NULL;
|
|
|
|
kfree(bqt);
|
|
}
|
|
|
|
q->queue_tags = NULL;
|
|
q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED);
|
|
}
|
|
|
|
/**
|
|
* blk_queue_free_tags - release tag maintenance info
|
|
* @q: the request queue for the device
|
|
*
|
|
* Notes:
|
|
* This is used to disabled tagged queuing to a device, yet leave
|
|
* queue in function.
|
|
**/
|
|
void blk_queue_free_tags(request_queue_t *q)
|
|
{
|
|
clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_free_tags);
|
|
|
|
static int
|
|
init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth)
|
|
{
|
|
struct request **tag_index;
|
|
unsigned long *tag_map;
|
|
int nr_ulongs;
|
|
|
|
if (depth > q->nr_requests * 2) {
|
|
depth = q->nr_requests * 2;
|
|
printk(KERN_ERR "%s: adjusted depth to %d\n",
|
|
__FUNCTION__, depth);
|
|
}
|
|
|
|
tag_index = kmalloc(depth * sizeof(struct request *), GFP_ATOMIC);
|
|
if (!tag_index)
|
|
goto fail;
|
|
|
|
nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG;
|
|
tag_map = kmalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC);
|
|
if (!tag_map)
|
|
goto fail;
|
|
|
|
memset(tag_index, 0, depth * sizeof(struct request *));
|
|
memset(tag_map, 0, nr_ulongs * sizeof(unsigned long));
|
|
tags->max_depth = depth;
|
|
tags->tag_index = tag_index;
|
|
tags->tag_map = tag_map;
|
|
|
|
return 0;
|
|
fail:
|
|
kfree(tag_index);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/**
|
|
* blk_queue_init_tags - initialize the queue tag info
|
|
* @q: the request queue for the device
|
|
* @depth: the maximum queue depth supported
|
|
* @tags: the tag to use
|
|
**/
|
|
int blk_queue_init_tags(request_queue_t *q, int depth,
|
|
struct blk_queue_tag *tags)
|
|
{
|
|
int rc;
|
|
|
|
BUG_ON(tags && q->queue_tags && tags != q->queue_tags);
|
|
|
|
if (!tags && !q->queue_tags) {
|
|
tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
|
|
if (!tags)
|
|
goto fail;
|
|
|
|
if (init_tag_map(q, tags, depth))
|
|
goto fail;
|
|
|
|
INIT_LIST_HEAD(&tags->busy_list);
|
|
tags->busy = 0;
|
|
atomic_set(&tags->refcnt, 1);
|
|
} else if (q->queue_tags) {
|
|
if ((rc = blk_queue_resize_tags(q, depth)))
|
|
return rc;
|
|
set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
|
|
return 0;
|
|
} else
|
|
atomic_inc(&tags->refcnt);
|
|
|
|
/*
|
|
* assign it, all done
|
|
*/
|
|
q->queue_tags = tags;
|
|
q->queue_flags |= (1 << QUEUE_FLAG_QUEUED);
|
|
return 0;
|
|
fail:
|
|
kfree(tags);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_init_tags);
|
|
|
|
/**
|
|
* blk_queue_resize_tags - change the queueing depth
|
|
* @q: the request queue for the device
|
|
* @new_depth: the new max command queueing depth
|
|
*
|
|
* Notes:
|
|
* Must be called with the queue lock held.
|
|
**/
|
|
int blk_queue_resize_tags(request_queue_t *q, int new_depth)
|
|
{
|
|
struct blk_queue_tag *bqt = q->queue_tags;
|
|
struct request **tag_index;
|
|
unsigned long *tag_map;
|
|
int max_depth, nr_ulongs;
|
|
|
|
if (!bqt)
|
|
return -ENXIO;
|
|
|
|
/*
|
|
* save the old state info, so we can copy it back
|
|
*/
|
|
tag_index = bqt->tag_index;
|
|
tag_map = bqt->tag_map;
|
|
max_depth = bqt->max_depth;
|
|
|
|
if (init_tag_map(q, bqt, new_depth))
|
|
return -ENOMEM;
|
|
|
|
memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *));
|
|
nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG;
|
|
memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long));
|
|
|
|
kfree(tag_index);
|
|
kfree(tag_map);
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_resize_tags);
|
|
|
|
/**
|
|
* blk_queue_end_tag - end tag operations for a request
|
|
* @q: the request queue for the device
|
|
* @rq: the request that has completed
|
|
*
|
|
* Description:
|
|
* Typically called when end_that_request_first() returns 0, meaning
|
|
* all transfers have been done for a request. It's important to call
|
|
* this function before end_that_request_last(), as that will put the
|
|
* request back on the free list thus corrupting the internal tag list.
|
|
*
|
|
* Notes:
|
|
* queue lock must be held.
|
|
**/
|
|
void blk_queue_end_tag(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct blk_queue_tag *bqt = q->queue_tags;
|
|
int tag = rq->tag;
|
|
|
|
BUG_ON(tag == -1);
|
|
|
|
if (unlikely(tag >= bqt->max_depth))
|
|
/*
|
|
* This can happen after tag depth has been reduced.
|
|
* FIXME: how about a warning or info message here?
|
|
*/
|
|
return;
|
|
|
|
if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) {
|
|
printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
|
|
__FUNCTION__, tag);
|
|
return;
|
|
}
|
|
|
|
list_del_init(&rq->queuelist);
|
|
rq->flags &= ~REQ_QUEUED;
|
|
rq->tag = -1;
|
|
|
|
if (unlikely(bqt->tag_index[tag] == NULL))
|
|
printk(KERN_ERR "%s: tag %d is missing\n",
|
|
__FUNCTION__, tag);
|
|
|
|
bqt->tag_index[tag] = NULL;
|
|
bqt->busy--;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_end_tag);
|
|
|
|
/**
|
|
* blk_queue_start_tag - find a free tag and assign it
|
|
* @q: the request queue for the device
|
|
* @rq: the block request that needs tagging
|
|
*
|
|
* Description:
|
|
* This can either be used as a stand-alone helper, or possibly be
|
|
* assigned as the queue &prep_rq_fn (in which case &struct request
|
|
* automagically gets a tag assigned). Note that this function
|
|
* assumes that any type of request can be queued! if this is not
|
|
* true for your device, you must check the request type before
|
|
* calling this function. The request will also be removed from
|
|
* the request queue, so it's the drivers responsibility to readd
|
|
* it if it should need to be restarted for some reason.
|
|
*
|
|
* Notes:
|
|
* queue lock must be held.
|
|
**/
|
|
int blk_queue_start_tag(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct blk_queue_tag *bqt = q->queue_tags;
|
|
int tag;
|
|
|
|
if (unlikely((rq->flags & REQ_QUEUED))) {
|
|
printk(KERN_ERR
|
|
"%s: request %p for device [%s] already tagged %d",
|
|
__FUNCTION__, rq,
|
|
rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag);
|
|
BUG();
|
|
}
|
|
|
|
tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth);
|
|
if (tag >= bqt->max_depth)
|
|
return 1;
|
|
|
|
__set_bit(tag, bqt->tag_map);
|
|
|
|
rq->flags |= REQ_QUEUED;
|
|
rq->tag = tag;
|
|
bqt->tag_index[tag] = rq;
|
|
blkdev_dequeue_request(rq);
|
|
list_add(&rq->queuelist, &bqt->busy_list);
|
|
bqt->busy++;
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_start_tag);
|
|
|
|
/**
|
|
* blk_queue_invalidate_tags - invalidate all pending tags
|
|
* @q: the request queue for the device
|
|
*
|
|
* Description:
|
|
* Hardware conditions may dictate a need to stop all pending requests.
|
|
* In this case, we will safely clear the block side of the tag queue and
|
|
* readd all requests to the request queue in the right order.
|
|
*
|
|
* Notes:
|
|
* queue lock must be held.
|
|
**/
|
|
void blk_queue_invalidate_tags(request_queue_t *q)
|
|
{
|
|
struct blk_queue_tag *bqt = q->queue_tags;
|
|
struct list_head *tmp, *n;
|
|
struct request *rq;
|
|
|
|
list_for_each_safe(tmp, n, &bqt->busy_list) {
|
|
rq = list_entry_rq(tmp);
|
|
|
|
if (rq->tag == -1) {
|
|
printk(KERN_ERR
|
|
"%s: bad tag found on list\n", __FUNCTION__);
|
|
list_del_init(&rq->queuelist);
|
|
rq->flags &= ~REQ_QUEUED;
|
|
} else
|
|
blk_queue_end_tag(q, rq);
|
|
|
|
rq->flags &= ~REQ_STARTED;
|
|
__elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
|
|
}
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_queue_invalidate_tags);
|
|
|
|
static char *rq_flags[] = {
|
|
"REQ_RW",
|
|
"REQ_FAILFAST",
|
|
"REQ_SOFTBARRIER",
|
|
"REQ_HARDBARRIER",
|
|
"REQ_CMD",
|
|
"REQ_NOMERGE",
|
|
"REQ_STARTED",
|
|
"REQ_DONTPREP",
|
|
"REQ_QUEUED",
|
|
"REQ_PC",
|
|
"REQ_BLOCK_PC",
|
|
"REQ_SENSE",
|
|
"REQ_FAILED",
|
|
"REQ_QUIET",
|
|
"REQ_SPECIAL",
|
|
"REQ_DRIVE_CMD",
|
|
"REQ_DRIVE_TASK",
|
|
"REQ_DRIVE_TASKFILE",
|
|
"REQ_PREEMPT",
|
|
"REQ_PM_SUSPEND",
|
|
"REQ_PM_RESUME",
|
|
"REQ_PM_SHUTDOWN",
|
|
};
|
|
|
|
void blk_dump_rq_flags(struct request *rq, char *msg)
|
|
{
|
|
int bit;
|
|
|
|
printk("%s: dev %s: flags = ", msg,
|
|
rq->rq_disk ? rq->rq_disk->disk_name : "?");
|
|
bit = 0;
|
|
do {
|
|
if (rq->flags & (1 << bit))
|
|
printk("%s ", rq_flags[bit]);
|
|
bit++;
|
|
} while (bit < __REQ_NR_BITS);
|
|
|
|
printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector,
|
|
rq->nr_sectors,
|
|
rq->current_nr_sectors);
|
|
printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len);
|
|
|
|
if (rq->flags & (REQ_BLOCK_PC | REQ_PC)) {
|
|
printk("cdb: ");
|
|
for (bit = 0; bit < sizeof(rq->cmd); bit++)
|
|
printk("%02x ", rq->cmd[bit]);
|
|
printk("\n");
|
|
}
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_dump_rq_flags);
|
|
|
|
void blk_recount_segments(request_queue_t *q, struct bio *bio)
|
|
{
|
|
struct bio_vec *bv, *bvprv = NULL;
|
|
int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster;
|
|
int high, highprv = 1;
|
|
|
|
if (unlikely(!bio->bi_io_vec))
|
|
return;
|
|
|
|
cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
|
|
hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0;
|
|
bio_for_each_segment(bv, bio, i) {
|
|
/*
|
|
* the trick here is making sure that a high page is never
|
|
* considered part of another segment, since that might
|
|
* change with the bounce page.
|
|
*/
|
|
high = page_to_pfn(bv->bv_page) >= q->bounce_pfn;
|
|
if (high || highprv)
|
|
goto new_hw_segment;
|
|
if (cluster) {
|
|
if (seg_size + bv->bv_len > q->max_segment_size)
|
|
goto new_segment;
|
|
if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
|
|
goto new_segment;
|
|
if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
|
|
goto new_segment;
|
|
if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
|
|
goto new_hw_segment;
|
|
|
|
seg_size += bv->bv_len;
|
|
hw_seg_size += bv->bv_len;
|
|
bvprv = bv;
|
|
continue;
|
|
}
|
|
new_segment:
|
|
if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
|
|
!BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) {
|
|
hw_seg_size += bv->bv_len;
|
|
} else {
|
|
new_hw_segment:
|
|
if (hw_seg_size > bio->bi_hw_front_size)
|
|
bio->bi_hw_front_size = hw_seg_size;
|
|
hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
|
|
nr_hw_segs++;
|
|
}
|
|
|
|
nr_phys_segs++;
|
|
bvprv = bv;
|
|
seg_size = bv->bv_len;
|
|
highprv = high;
|
|
}
|
|
if (hw_seg_size > bio->bi_hw_back_size)
|
|
bio->bi_hw_back_size = hw_seg_size;
|
|
if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size)
|
|
bio->bi_hw_front_size = hw_seg_size;
|
|
bio->bi_phys_segments = nr_phys_segs;
|
|
bio->bi_hw_segments = nr_hw_segs;
|
|
bio->bi_flags |= (1 << BIO_SEG_VALID);
|
|
}
|
|
|
|
|
|
static int blk_phys_contig_segment(request_queue_t *q, struct bio *bio,
|
|
struct bio *nxt)
|
|
{
|
|
if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
|
|
return 0;
|
|
|
|
if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
|
|
return 0;
|
|
if (bio->bi_size + nxt->bi_size > q->max_segment_size)
|
|
return 0;
|
|
|
|
/*
|
|
* bio and nxt are contigous in memory, check if the queue allows
|
|
* these two to be merged into one
|
|
*/
|
|
if (BIO_SEG_BOUNDARY(q, bio, nxt))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int blk_hw_contig_segment(request_queue_t *q, struct bio *bio,
|
|
struct bio *nxt)
|
|
{
|
|
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
|
|
blk_recount_segments(q, bio);
|
|
if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID)))
|
|
blk_recount_segments(q, nxt);
|
|
if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
|
|
BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size))
|
|
return 0;
|
|
if (bio->bi_size + nxt->bi_size > q->max_segment_size)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* map a request to scatterlist, return number of sg entries setup. Caller
|
|
* must make sure sg can hold rq->nr_phys_segments entries
|
|
*/
|
|
int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg)
|
|
{
|
|
struct bio_vec *bvec, *bvprv;
|
|
struct bio *bio;
|
|
int nsegs, i, cluster;
|
|
|
|
nsegs = 0;
|
|
cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
|
|
|
|
/*
|
|
* for each bio in rq
|
|
*/
|
|
bvprv = NULL;
|
|
rq_for_each_bio(bio, rq) {
|
|
/*
|
|
* for each segment in bio
|
|
*/
|
|
bio_for_each_segment(bvec, bio, i) {
|
|
int nbytes = bvec->bv_len;
|
|
|
|
if (bvprv && cluster) {
|
|
if (sg[nsegs - 1].length + nbytes > q->max_segment_size)
|
|
goto new_segment;
|
|
|
|
if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
|
|
goto new_segment;
|
|
if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
|
|
goto new_segment;
|
|
|
|
sg[nsegs - 1].length += nbytes;
|
|
} else {
|
|
new_segment:
|
|
memset(&sg[nsegs],0,sizeof(struct scatterlist));
|
|
sg[nsegs].page = bvec->bv_page;
|
|
sg[nsegs].length = nbytes;
|
|
sg[nsegs].offset = bvec->bv_offset;
|
|
|
|
nsegs++;
|
|
}
|
|
bvprv = bvec;
|
|
} /* segments in bio */
|
|
} /* bios in rq */
|
|
|
|
return nsegs;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_rq_map_sg);
|
|
|
|
/*
|
|
* the standard queue merge functions, can be overridden with device
|
|
* specific ones if so desired
|
|
*/
|
|
|
|
static inline int ll_new_mergeable(request_queue_t *q,
|
|
struct request *req,
|
|
struct bio *bio)
|
|
{
|
|
int nr_phys_segs = bio_phys_segments(q, bio);
|
|
|
|
if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
|
|
req->flags |= REQ_NOMERGE;
|
|
if (req == q->last_merge)
|
|
q->last_merge = NULL;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* A hw segment is just getting larger, bump just the phys
|
|
* counter.
|
|
*/
|
|
req->nr_phys_segments += nr_phys_segs;
|
|
return 1;
|
|
}
|
|
|
|
static inline int ll_new_hw_segment(request_queue_t *q,
|
|
struct request *req,
|
|
struct bio *bio)
|
|
{
|
|
int nr_hw_segs = bio_hw_segments(q, bio);
|
|
int nr_phys_segs = bio_phys_segments(q, bio);
|
|
|
|
if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments
|
|
|| req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
|
|
req->flags |= REQ_NOMERGE;
|
|
if (req == q->last_merge)
|
|
q->last_merge = NULL;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* This will form the start of a new hw segment. Bump both
|
|
* counters.
|
|
*/
|
|
req->nr_hw_segments += nr_hw_segs;
|
|
req->nr_phys_segments += nr_phys_segs;
|
|
return 1;
|
|
}
|
|
|
|
static int ll_back_merge_fn(request_queue_t *q, struct request *req,
|
|
struct bio *bio)
|
|
{
|
|
int len;
|
|
|
|
if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) {
|
|
req->flags |= REQ_NOMERGE;
|
|
if (req == q->last_merge)
|
|
q->last_merge = NULL;
|
|
return 0;
|
|
}
|
|
if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID)))
|
|
blk_recount_segments(q, req->biotail);
|
|
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
|
|
blk_recount_segments(q, bio);
|
|
len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
|
|
if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) &&
|
|
!BIOVEC_VIRT_OVERSIZE(len)) {
|
|
int mergeable = ll_new_mergeable(q, req, bio);
|
|
|
|
if (mergeable) {
|
|
if (req->nr_hw_segments == 1)
|
|
req->bio->bi_hw_front_size = len;
|
|
if (bio->bi_hw_segments == 1)
|
|
bio->bi_hw_back_size = len;
|
|
}
|
|
return mergeable;
|
|
}
|
|
|
|
return ll_new_hw_segment(q, req, bio);
|
|
}
|
|
|
|
static int ll_front_merge_fn(request_queue_t *q, struct request *req,
|
|
struct bio *bio)
|
|
{
|
|
int len;
|
|
|
|
if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) {
|
|
req->flags |= REQ_NOMERGE;
|
|
if (req == q->last_merge)
|
|
q->last_merge = NULL;
|
|
return 0;
|
|
}
|
|
len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
|
|
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
|
|
blk_recount_segments(q, bio);
|
|
if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID)))
|
|
blk_recount_segments(q, req->bio);
|
|
if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
|
|
!BIOVEC_VIRT_OVERSIZE(len)) {
|
|
int mergeable = ll_new_mergeable(q, req, bio);
|
|
|
|
if (mergeable) {
|
|
if (bio->bi_hw_segments == 1)
|
|
bio->bi_hw_front_size = len;
|
|
if (req->nr_hw_segments == 1)
|
|
req->biotail->bi_hw_back_size = len;
|
|
}
|
|
return mergeable;
|
|
}
|
|
|
|
return ll_new_hw_segment(q, req, bio);
|
|
}
|
|
|
|
static int ll_merge_requests_fn(request_queue_t *q, struct request *req,
|
|
struct request *next)
|
|
{
|
|
int total_phys_segments;
|
|
int total_hw_segments;
|
|
|
|
/*
|
|
* First check if the either of the requests are re-queued
|
|
* requests. Can't merge them if they are.
|
|
*/
|
|
if (req->special || next->special)
|
|
return 0;
|
|
|
|
/*
|
|
* Will it become too large?
|
|
*/
|
|
if ((req->nr_sectors + next->nr_sectors) > q->max_sectors)
|
|
return 0;
|
|
|
|
total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
|
|
if (blk_phys_contig_segment(q, req->biotail, next->bio))
|
|
total_phys_segments--;
|
|
|
|
if (total_phys_segments > q->max_phys_segments)
|
|
return 0;
|
|
|
|
total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
|
|
if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
|
|
int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size;
|
|
/*
|
|
* propagate the combined length to the end of the requests
|
|
*/
|
|
if (req->nr_hw_segments == 1)
|
|
req->bio->bi_hw_front_size = len;
|
|
if (next->nr_hw_segments == 1)
|
|
next->biotail->bi_hw_back_size = len;
|
|
total_hw_segments--;
|
|
}
|
|
|
|
if (total_hw_segments > q->max_hw_segments)
|
|
return 0;
|
|
|
|
/* Merge is OK... */
|
|
req->nr_phys_segments = total_phys_segments;
|
|
req->nr_hw_segments = total_hw_segments;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* "plug" the device if there are no outstanding requests: this will
|
|
* force the transfer to start only after we have put all the requests
|
|
* on the list.
|
|
*
|
|
* This is called with interrupts off and no requests on the queue and
|
|
* with the queue lock held.
|
|
*/
|
|
void blk_plug_device(request_queue_t *q)
|
|
{
|
|
WARN_ON(!irqs_disabled());
|
|
|
|
/*
|
|
* don't plug a stopped queue, it must be paired with blk_start_queue()
|
|
* which will restart the queueing
|
|
*/
|
|
if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))
|
|
return;
|
|
|
|
if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
|
|
mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_plug_device);
|
|
|
|
/*
|
|
* remove the queue from the plugged list, if present. called with
|
|
* queue lock held and interrupts disabled.
|
|
*/
|
|
int blk_remove_plug(request_queue_t *q)
|
|
{
|
|
WARN_ON(!irqs_disabled());
|
|
|
|
if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
|
|
return 0;
|
|
|
|
del_timer(&q->unplug_timer);
|
|
return 1;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_remove_plug);
|
|
|
|
/*
|
|
* remove the plug and let it rip..
|
|
*/
|
|
void __generic_unplug_device(request_queue_t *q)
|
|
{
|
|
if (unlikely(test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)))
|
|
return;
|
|
|
|
if (!blk_remove_plug(q))
|
|
return;
|
|
|
|
q->request_fn(q);
|
|
}
|
|
EXPORT_SYMBOL(__generic_unplug_device);
|
|
|
|
/**
|
|
* generic_unplug_device - fire a request queue
|
|
* @q: The &request_queue_t in question
|
|
*
|
|
* Description:
|
|
* Linux uses plugging to build bigger requests queues before letting
|
|
* the device have at them. If a queue is plugged, the I/O scheduler
|
|
* is still adding and merging requests on the queue. Once the queue
|
|
* gets unplugged, the request_fn defined for the queue is invoked and
|
|
* transfers started.
|
|
**/
|
|
void generic_unplug_device(request_queue_t *q)
|
|
{
|
|
spin_lock_irq(q->queue_lock);
|
|
__generic_unplug_device(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
EXPORT_SYMBOL(generic_unplug_device);
|
|
|
|
static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
|
|
struct page *page)
|
|
{
|
|
request_queue_t *q = bdi->unplug_io_data;
|
|
|
|
/*
|
|
* devices don't necessarily have an ->unplug_fn defined
|
|
*/
|
|
if (q->unplug_fn)
|
|
q->unplug_fn(q);
|
|
}
|
|
|
|
static void blk_unplug_work(void *data)
|
|
{
|
|
request_queue_t *q = data;
|
|
|
|
q->unplug_fn(q);
|
|
}
|
|
|
|
static void blk_unplug_timeout(unsigned long data)
|
|
{
|
|
request_queue_t *q = (request_queue_t *)data;
|
|
|
|
kblockd_schedule_work(&q->unplug_work);
|
|
}
|
|
|
|
/**
|
|
* blk_start_queue - restart a previously stopped queue
|
|
* @q: The &request_queue_t in question
|
|
*
|
|
* Description:
|
|
* blk_start_queue() will clear the stop flag on the queue, and call
|
|
* the request_fn for the queue if it was in a stopped state when
|
|
* entered. Also see blk_stop_queue(). Queue lock must be held.
|
|
**/
|
|
void blk_start_queue(request_queue_t *q)
|
|
{
|
|
clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
|
|
|
|
/*
|
|
* one level of recursion is ok and is much faster than kicking
|
|
* the unplug handling
|
|
*/
|
|
if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
|
|
q->request_fn(q);
|
|
clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
|
|
} else {
|
|
blk_plug_device(q);
|
|
kblockd_schedule_work(&q->unplug_work);
|
|
}
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_start_queue);
|
|
|
|
/**
|
|
* blk_stop_queue - stop a queue
|
|
* @q: The &request_queue_t in question
|
|
*
|
|
* Description:
|
|
* The Linux block layer assumes that a block driver will consume all
|
|
* entries on the request queue when the request_fn strategy is called.
|
|
* Often this will not happen, because of hardware limitations (queue
|
|
* depth settings). If a device driver gets a 'queue full' response,
|
|
* or if it simply chooses not to queue more I/O at one point, it can
|
|
* call this function to prevent the request_fn from being called until
|
|
* the driver has signalled it's ready to go again. This happens by calling
|
|
* blk_start_queue() to restart queue operations. Queue lock must be held.
|
|
**/
|
|
void blk_stop_queue(request_queue_t *q)
|
|
{
|
|
blk_remove_plug(q);
|
|
set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
|
|
}
|
|
EXPORT_SYMBOL(blk_stop_queue);
|
|
|
|
/**
|
|
* blk_sync_queue - cancel any pending callbacks on a queue
|
|
* @q: the queue
|
|
*
|
|
* Description:
|
|
* The block layer may perform asynchronous callback activity
|
|
* on a queue, such as calling the unplug function after a timeout.
|
|
* A block device may call blk_sync_queue to ensure that any
|
|
* such activity is cancelled, thus allowing it to release resources
|
|
* the the callbacks might use. The caller must already have made sure
|
|
* that its ->make_request_fn will not re-add plugging prior to calling
|
|
* this function.
|
|
*
|
|
*/
|
|
void blk_sync_queue(struct request_queue *q)
|
|
{
|
|
del_timer_sync(&q->unplug_timer);
|
|
kblockd_flush();
|
|
}
|
|
EXPORT_SYMBOL(blk_sync_queue);
|
|
|
|
/**
|
|
* blk_run_queue - run a single device queue
|
|
* @q: The queue to run
|
|
*/
|
|
void blk_run_queue(struct request_queue *q)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
blk_remove_plug(q);
|
|
if (!elv_queue_empty(q))
|
|
q->request_fn(q);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(blk_run_queue);
|
|
|
|
/**
|
|
* blk_cleanup_queue: - release a &request_queue_t when it is no longer needed
|
|
* @q: the request queue to be released
|
|
*
|
|
* Description:
|
|
* blk_cleanup_queue is the pair to blk_init_queue() or
|
|
* blk_queue_make_request(). It should be called when a request queue is
|
|
* being released; typically when a block device is being de-registered.
|
|
* Currently, its primary task it to free all the &struct request
|
|
* structures that were allocated to the queue and the queue itself.
|
|
*
|
|
* Caveat:
|
|
* Hopefully the low level driver will have finished any
|
|
* outstanding requests first...
|
|
**/
|
|
void blk_cleanup_queue(request_queue_t * q)
|
|
{
|
|
struct request_list *rl = &q->rq;
|
|
|
|
if (!atomic_dec_and_test(&q->refcnt))
|
|
return;
|
|
|
|
if (q->elevator)
|
|
elevator_exit(q->elevator);
|
|
|
|
blk_sync_queue(q);
|
|
|
|
if (rl->rq_pool)
|
|
mempool_destroy(rl->rq_pool);
|
|
|
|
if (q->queue_tags)
|
|
__blk_queue_free_tags(q);
|
|
|
|
blk_queue_ordered(q, QUEUE_ORDERED_NONE);
|
|
|
|
kmem_cache_free(requestq_cachep, q);
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_cleanup_queue);
|
|
|
|
static int blk_init_free_list(request_queue_t *q)
|
|
{
|
|
struct request_list *rl = &q->rq;
|
|
|
|
rl->count[READ] = rl->count[WRITE] = 0;
|
|
rl->starved[READ] = rl->starved[WRITE] = 0;
|
|
init_waitqueue_head(&rl->wait[READ]);
|
|
init_waitqueue_head(&rl->wait[WRITE]);
|
|
init_waitqueue_head(&rl->drain);
|
|
|
|
rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
|
|
mempool_free_slab, request_cachep, q->node);
|
|
|
|
if (!rl->rq_pool)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __make_request(request_queue_t *, struct bio *);
|
|
|
|
request_queue_t *blk_alloc_queue(int gfp_mask)
|
|
{
|
|
return blk_alloc_queue_node(gfp_mask, -1);
|
|
}
|
|
EXPORT_SYMBOL(blk_alloc_queue);
|
|
|
|
request_queue_t *blk_alloc_queue_node(int gfp_mask, int node_id)
|
|
{
|
|
request_queue_t *q;
|
|
|
|
q = kmem_cache_alloc_node(requestq_cachep, gfp_mask, node_id);
|
|
if (!q)
|
|
return NULL;
|
|
|
|
memset(q, 0, sizeof(*q));
|
|
init_timer(&q->unplug_timer);
|
|
atomic_set(&q->refcnt, 1);
|
|
|
|
q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
|
|
q->backing_dev_info.unplug_io_data = q;
|
|
|
|
return q;
|
|
}
|
|
EXPORT_SYMBOL(blk_alloc_queue_node);
|
|
|
|
/**
|
|
* blk_init_queue - prepare a request queue for use with a block device
|
|
* @rfn: The function to be called to process requests that have been
|
|
* placed on the queue.
|
|
* @lock: Request queue spin lock
|
|
*
|
|
* Description:
|
|
* If a block device wishes to use the standard request handling procedures,
|
|
* which sorts requests and coalesces adjacent requests, then it must
|
|
* call blk_init_queue(). The function @rfn will be called when there
|
|
* are requests on the queue that need to be processed. If the device
|
|
* supports plugging, then @rfn may not be called immediately when requests
|
|
* are available on the queue, but may be called at some time later instead.
|
|
* Plugged queues are generally unplugged when a buffer belonging to one
|
|
* of the requests on the queue is needed, or due to memory pressure.
|
|
*
|
|
* @rfn is not required, or even expected, to remove all requests off the
|
|
* queue, but only as many as it can handle at a time. If it does leave
|
|
* requests on the queue, it is responsible for arranging that the requests
|
|
* get dealt with eventually.
|
|
*
|
|
* The queue spin lock must be held while manipulating the requests on the
|
|
* request queue.
|
|
*
|
|
* Function returns a pointer to the initialized request queue, or NULL if
|
|
* it didn't succeed.
|
|
*
|
|
* Note:
|
|
* blk_init_queue() must be paired with a blk_cleanup_queue() call
|
|
* when the block device is deactivated (such as at module unload).
|
|
**/
|
|
|
|
request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
|
|
{
|
|
return blk_init_queue_node(rfn, lock, -1);
|
|
}
|
|
EXPORT_SYMBOL(blk_init_queue);
|
|
|
|
request_queue_t *
|
|
blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
|
|
{
|
|
request_queue_t *q = blk_alloc_queue_node(GFP_KERNEL, node_id);
|
|
|
|
if (!q)
|
|
return NULL;
|
|
|
|
q->node = node_id;
|
|
if (blk_init_free_list(q))
|
|
goto out_init;
|
|
|
|
/*
|
|
* if caller didn't supply a lock, they get per-queue locking with
|
|
* our embedded lock
|
|
*/
|
|
if (!lock) {
|
|
spin_lock_init(&q->__queue_lock);
|
|
lock = &q->__queue_lock;
|
|
}
|
|
|
|
q->request_fn = rfn;
|
|
q->back_merge_fn = ll_back_merge_fn;
|
|
q->front_merge_fn = ll_front_merge_fn;
|
|
q->merge_requests_fn = ll_merge_requests_fn;
|
|
q->prep_rq_fn = NULL;
|
|
q->unplug_fn = generic_unplug_device;
|
|
q->queue_flags = (1 << QUEUE_FLAG_CLUSTER);
|
|
q->queue_lock = lock;
|
|
|
|
blk_queue_segment_boundary(q, 0xffffffff);
|
|
|
|
blk_queue_make_request(q, __make_request);
|
|
blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
|
|
|
|
blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
|
|
blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
|
|
|
|
/*
|
|
* all done
|
|
*/
|
|
if (!elevator_init(q, NULL)) {
|
|
blk_queue_congestion_threshold(q);
|
|
return q;
|
|
}
|
|
|
|
blk_cleanup_queue(q);
|
|
out_init:
|
|
kmem_cache_free(requestq_cachep, q);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(blk_init_queue_node);
|
|
|
|
int blk_get_queue(request_queue_t *q)
|
|
{
|
|
if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
|
|
atomic_inc(&q->refcnt);
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_get_queue);
|
|
|
|
static inline void blk_free_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
elv_put_request(q, rq);
|
|
mempool_free(rq, q->rq.rq_pool);
|
|
}
|
|
|
|
static inline struct request *
|
|
blk_alloc_request(request_queue_t *q, int rw, struct bio *bio, int gfp_mask)
|
|
{
|
|
struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
|
|
|
|
if (!rq)
|
|
return NULL;
|
|
|
|
/*
|
|
* first three bits are identical in rq->flags and bio->bi_rw,
|
|
* see bio.h and blkdev.h
|
|
*/
|
|
rq->flags = rw;
|
|
|
|
if (!elv_set_request(q, rq, bio, gfp_mask))
|
|
return rq;
|
|
|
|
mempool_free(rq, q->rq.rq_pool);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* ioc_batching returns true if the ioc is a valid batching request and
|
|
* should be given priority access to a request.
|
|
*/
|
|
static inline int ioc_batching(request_queue_t *q, struct io_context *ioc)
|
|
{
|
|
if (!ioc)
|
|
return 0;
|
|
|
|
/*
|
|
* Make sure the process is able to allocate at least 1 request
|
|
* even if the batch times out, otherwise we could theoretically
|
|
* lose wakeups.
|
|
*/
|
|
return ioc->nr_batch_requests == q->nr_batching ||
|
|
(ioc->nr_batch_requests > 0
|
|
&& time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
|
|
}
|
|
|
|
/*
|
|
* ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
|
|
* will cause the process to be a "batcher" on all queues in the system. This
|
|
* is the behaviour we want though - once it gets a wakeup it should be given
|
|
* a nice run.
|
|
*/
|
|
static void ioc_set_batching(request_queue_t *q, struct io_context *ioc)
|
|
{
|
|
if (!ioc || ioc_batching(q, ioc))
|
|
return;
|
|
|
|
ioc->nr_batch_requests = q->nr_batching;
|
|
ioc->last_waited = jiffies;
|
|
}
|
|
|
|
static void __freed_request(request_queue_t *q, int rw)
|
|
{
|
|
struct request_list *rl = &q->rq;
|
|
|
|
if (rl->count[rw] < queue_congestion_off_threshold(q))
|
|
clear_queue_congested(q, rw);
|
|
|
|
if (rl->count[rw] + 1 <= q->nr_requests) {
|
|
if (waitqueue_active(&rl->wait[rw]))
|
|
wake_up(&rl->wait[rw]);
|
|
|
|
blk_clear_queue_full(q, rw);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* A request has just been released. Account for it, update the full and
|
|
* congestion status, wake up any waiters. Called under q->queue_lock.
|
|
*/
|
|
static void freed_request(request_queue_t *q, int rw)
|
|
{
|
|
struct request_list *rl = &q->rq;
|
|
|
|
rl->count[rw]--;
|
|
|
|
__freed_request(q, rw);
|
|
|
|
if (unlikely(rl->starved[rw ^ 1]))
|
|
__freed_request(q, rw ^ 1);
|
|
|
|
if (!rl->count[READ] && !rl->count[WRITE]) {
|
|
smp_mb();
|
|
if (unlikely(waitqueue_active(&rl->drain)))
|
|
wake_up(&rl->drain);
|
|
}
|
|
}
|
|
|
|
#define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
|
|
/*
|
|
* Get a free request, queue_lock must be held.
|
|
* Returns NULL on failure, with queue_lock held.
|
|
* Returns !NULL on success, with queue_lock *not held*.
|
|
*/
|
|
static struct request *get_request(request_queue_t *q, int rw, struct bio *bio,
|
|
int gfp_mask)
|
|
{
|
|
struct request *rq = NULL;
|
|
struct request_list *rl = &q->rq;
|
|
struct io_context *ioc = current_io_context(GFP_ATOMIC);
|
|
|
|
if (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)))
|
|
goto out;
|
|
|
|
if (rl->count[rw]+1 >= q->nr_requests) {
|
|
/*
|
|
* The queue will fill after this allocation, so set it as
|
|
* full, and mark this process as "batching". This process
|
|
* will be allowed to complete a batch of requests, others
|
|
* will be blocked.
|
|
*/
|
|
if (!blk_queue_full(q, rw)) {
|
|
ioc_set_batching(q, ioc);
|
|
blk_set_queue_full(q, rw);
|
|
}
|
|
}
|
|
|
|
switch (elv_may_queue(q, rw, bio)) {
|
|
case ELV_MQUEUE_NO:
|
|
goto rq_starved;
|
|
case ELV_MQUEUE_MAY:
|
|
break;
|
|
case ELV_MQUEUE_MUST:
|
|
goto get_rq;
|
|
}
|
|
|
|
if (blk_queue_full(q, rw) && !ioc_batching(q, ioc)) {
|
|
/*
|
|
* The queue is full and the allocating process is not a
|
|
* "batcher", and not exempted by the IO scheduler
|
|
*/
|
|
goto out;
|
|
}
|
|
|
|
get_rq:
|
|
/*
|
|
* Only allow batching queuers to allocate up to 50% over the defined
|
|
* limit of requests, otherwise we could have thousands of requests
|
|
* allocated with any setting of ->nr_requests
|
|
*/
|
|
if (rl->count[rw] >= (3 * q->nr_requests / 2))
|
|
goto out;
|
|
|
|
rl->count[rw]++;
|
|
rl->starved[rw] = 0;
|
|
if (rl->count[rw] >= queue_congestion_on_threshold(q))
|
|
set_queue_congested(q, rw);
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
rq = blk_alloc_request(q, rw, bio, gfp_mask);
|
|
if (!rq) {
|
|
/*
|
|
* Allocation failed presumably due to memory. Undo anything
|
|
* we might have messed up.
|
|
*
|
|
* Allocating task should really be put onto the front of the
|
|
* wait queue, but this is pretty rare.
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
freed_request(q, rw);
|
|
|
|
/*
|
|
* in the very unlikely event that allocation failed and no
|
|
* requests for this direction was pending, mark us starved
|
|
* so that freeing of a request in the other direction will
|
|
* notice us. another possible fix would be to split the
|
|
* rq mempool into READ and WRITE
|
|
*/
|
|
rq_starved:
|
|
if (unlikely(rl->count[rw] == 0))
|
|
rl->starved[rw] = 1;
|
|
|
|
goto out;
|
|
}
|
|
|
|
if (ioc_batching(q, ioc))
|
|
ioc->nr_batch_requests--;
|
|
|
|
rq_init(q, rq);
|
|
rq->rl = rl;
|
|
out:
|
|
return rq;
|
|
}
|
|
|
|
/*
|
|
* No available requests for this queue, unplug the device and wait for some
|
|
* requests to become available.
|
|
*
|
|
* Called with q->queue_lock held, and returns with it unlocked.
|
|
*/
|
|
static struct request *get_request_wait(request_queue_t *q, int rw,
|
|
struct bio *bio)
|
|
{
|
|
struct request *rq;
|
|
|
|
rq = get_request(q, rw, bio, GFP_NOIO);
|
|
while (!rq) {
|
|
DEFINE_WAIT(wait);
|
|
struct request_list *rl = &q->rq;
|
|
|
|
prepare_to_wait_exclusive(&rl->wait[rw], &wait,
|
|
TASK_UNINTERRUPTIBLE);
|
|
|
|
rq = get_request(q, rw, bio, GFP_NOIO);
|
|
|
|
if (!rq) {
|
|
struct io_context *ioc;
|
|
|
|
__generic_unplug_device(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
io_schedule();
|
|
|
|
/*
|
|
* After sleeping, we become a "batching" process and
|
|
* will be able to allocate at least one request, and
|
|
* up to a big batch of them for a small period time.
|
|
* See ioc_batching, ioc_set_batching
|
|
*/
|
|
ioc = current_io_context(GFP_NOIO);
|
|
ioc_set_batching(q, ioc);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
}
|
|
finish_wait(&rl->wait[rw], &wait);
|
|
}
|
|
|
|
return rq;
|
|
}
|
|
|
|
struct request *blk_get_request(request_queue_t *q, int rw, int gfp_mask)
|
|
{
|
|
struct request *rq;
|
|
|
|
BUG_ON(rw != READ && rw != WRITE);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
if (gfp_mask & __GFP_WAIT) {
|
|
rq = get_request_wait(q, rw, NULL);
|
|
} else {
|
|
rq = get_request(q, rw, NULL, gfp_mask);
|
|
if (!rq)
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
/* q->queue_lock is unlocked at this point */
|
|
|
|
return rq;
|
|
}
|
|
EXPORT_SYMBOL(blk_get_request);
|
|
|
|
/**
|
|
* blk_requeue_request - put a request back on queue
|
|
* @q: request queue where request should be inserted
|
|
* @rq: request to be inserted
|
|
*
|
|
* Description:
|
|
* Drivers often keep queueing requests until the hardware cannot accept
|
|
* more, when that condition happens we need to put the request back
|
|
* on the queue. Must be called with queue lock held.
|
|
*/
|
|
void blk_requeue_request(request_queue_t *q, struct request *rq)
|
|
{
|
|
if (blk_rq_tagged(rq))
|
|
blk_queue_end_tag(q, rq);
|
|
|
|
elv_requeue_request(q, rq);
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_requeue_request);
|
|
|
|
/**
|
|
* blk_insert_request - insert a special request in to a request queue
|
|
* @q: request queue where request should be inserted
|
|
* @rq: request to be inserted
|
|
* @at_head: insert request at head or tail of queue
|
|
* @data: private data
|
|
*
|
|
* Description:
|
|
* Many block devices need to execute commands asynchronously, so they don't
|
|
* block the whole kernel from preemption during request execution. This is
|
|
* accomplished normally by inserting aritficial requests tagged as
|
|
* REQ_SPECIAL in to the corresponding request queue, and letting them be
|
|
* scheduled for actual execution by the request queue.
|
|
*
|
|
* We have the option of inserting the head or the tail of the queue.
|
|
* Typically we use the tail for new ioctls and so forth. We use the head
|
|
* of the queue for things like a QUEUE_FULL message from a device, or a
|
|
* host that is unable to accept a particular command.
|
|
*/
|
|
void blk_insert_request(request_queue_t *q, struct request *rq,
|
|
int at_head, void *data)
|
|
{
|
|
int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* tell I/O scheduler that this isn't a regular read/write (ie it
|
|
* must not attempt merges on this) and that it acts as a soft
|
|
* barrier
|
|
*/
|
|
rq->flags |= REQ_SPECIAL | REQ_SOFTBARRIER;
|
|
|
|
rq->special = data;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
/*
|
|
* If command is tagged, release the tag
|
|
*/
|
|
if (blk_rq_tagged(rq))
|
|
blk_queue_end_tag(q, rq);
|
|
|
|
drive_stat_acct(rq, rq->nr_sectors, 1);
|
|
__elv_add_request(q, rq, where, 0);
|
|
|
|
if (blk_queue_plugged(q))
|
|
__generic_unplug_device(q);
|
|
else
|
|
q->request_fn(q);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_insert_request);
|
|
|
|
/**
|
|
* blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
|
|
* @q: request queue where request should be inserted
|
|
* @rw: READ or WRITE data
|
|
* @ubuf: the user buffer
|
|
* @len: length of user data
|
|
*
|
|
* Description:
|
|
* Data will be mapped directly for zero copy io, if possible. Otherwise
|
|
* a kernel bounce buffer is used.
|
|
*
|
|
* A matching blk_rq_unmap_user() must be issued at the end of io, while
|
|
* still in process context.
|
|
*
|
|
* Note: The mapped bio may need to be bounced through blk_queue_bounce()
|
|
* before being submitted to the device, as pages mapped may be out of
|
|
* reach. It's the callers responsibility to make sure this happens. The
|
|
* original bio must be passed back in to blk_rq_unmap_user() for proper
|
|
* unmapping.
|
|
*/
|
|
struct request *blk_rq_map_user(request_queue_t *q, int rw, void __user *ubuf,
|
|
unsigned int len)
|
|
{
|
|
unsigned long uaddr;
|
|
struct request *rq;
|
|
struct bio *bio;
|
|
|
|
if (len > (q->max_sectors << 9))
|
|
return ERR_PTR(-EINVAL);
|
|
if ((!len && ubuf) || (len && !ubuf))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
rq = blk_get_request(q, rw, __GFP_WAIT);
|
|
if (!rq)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
/*
|
|
* if alignment requirement is satisfied, map in user pages for
|
|
* direct dma. else, set up kernel bounce buffers
|
|
*/
|
|
uaddr = (unsigned long) ubuf;
|
|
if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
|
|
bio = bio_map_user(q, NULL, uaddr, len, rw == READ);
|
|
else
|
|
bio = bio_copy_user(q, uaddr, len, rw == READ);
|
|
|
|
if (!IS_ERR(bio)) {
|
|
rq->bio = rq->biotail = bio;
|
|
blk_rq_bio_prep(q, rq, bio);
|
|
|
|
rq->buffer = rq->data = NULL;
|
|
rq->data_len = len;
|
|
return rq;
|
|
}
|
|
|
|
/*
|
|
* bio is the err-ptr
|
|
*/
|
|
blk_put_request(rq);
|
|
return (struct request *) bio;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_rq_map_user);
|
|
|
|
/**
|
|
* blk_rq_unmap_user - unmap a request with user data
|
|
* @rq: request to be unmapped
|
|
* @bio: bio for the request
|
|
* @ulen: length of user buffer
|
|
*
|
|
* Description:
|
|
* Unmap a request previously mapped by blk_rq_map_user().
|
|
*/
|
|
int blk_rq_unmap_user(struct request *rq, struct bio *bio, unsigned int ulen)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (bio) {
|
|
if (bio_flagged(bio, BIO_USER_MAPPED))
|
|
bio_unmap_user(bio);
|
|
else
|
|
ret = bio_uncopy_user(bio);
|
|
}
|
|
|
|
blk_put_request(rq);
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_rq_unmap_user);
|
|
|
|
/**
|
|
* blk_execute_rq - insert a request into queue for execution
|
|
* @q: queue to insert the request in
|
|
* @bd_disk: matching gendisk
|
|
* @rq: request to insert
|
|
*
|
|
* Description:
|
|
* Insert a fully prepared request at the back of the io scheduler queue
|
|
* for execution.
|
|
*/
|
|
int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk,
|
|
struct request *rq)
|
|
{
|
|
DECLARE_COMPLETION(wait);
|
|
char sense[SCSI_SENSE_BUFFERSIZE];
|
|
int err = 0;
|
|
|
|
rq->rq_disk = bd_disk;
|
|
|
|
/*
|
|
* we need an extra reference to the request, so we can look at
|
|
* it after io completion
|
|
*/
|
|
rq->ref_count++;
|
|
|
|
if (!rq->sense) {
|
|
memset(sense, 0, sizeof(sense));
|
|
rq->sense = sense;
|
|
rq->sense_len = 0;
|
|
}
|
|
|
|
rq->flags |= REQ_NOMERGE;
|
|
rq->waiting = &wait;
|
|
rq->end_io = blk_end_sync_rq;
|
|
elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 1);
|
|
generic_unplug_device(q);
|
|
wait_for_completion(&wait);
|
|
rq->waiting = NULL;
|
|
|
|
if (rq->errors)
|
|
err = -EIO;
|
|
|
|
return err;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_execute_rq);
|
|
|
|
/**
|
|
* blkdev_issue_flush - queue a flush
|
|
* @bdev: blockdev to issue flush for
|
|
* @error_sector: error sector
|
|
*
|
|
* Description:
|
|
* Issue a flush for the block device in question. Caller can supply
|
|
* room for storing the error offset in case of a flush error, if they
|
|
* wish to. Caller must run wait_for_completion() on its own.
|
|
*/
|
|
int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
|
|
{
|
|
request_queue_t *q;
|
|
|
|
if (bdev->bd_disk == NULL)
|
|
return -ENXIO;
|
|
|
|
q = bdev_get_queue(bdev);
|
|
if (!q)
|
|
return -ENXIO;
|
|
if (!q->issue_flush_fn)
|
|
return -EOPNOTSUPP;
|
|
|
|
return q->issue_flush_fn(q, bdev->bd_disk, error_sector);
|
|
}
|
|
|
|
EXPORT_SYMBOL(blkdev_issue_flush);
|
|
|
|
static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io)
|
|
{
|
|
int rw = rq_data_dir(rq);
|
|
|
|
if (!blk_fs_request(rq) || !rq->rq_disk)
|
|
return;
|
|
|
|
if (rw == READ) {
|
|
__disk_stat_add(rq->rq_disk, read_sectors, nr_sectors);
|
|
if (!new_io)
|
|
__disk_stat_inc(rq->rq_disk, read_merges);
|
|
} else if (rw == WRITE) {
|
|
__disk_stat_add(rq->rq_disk, write_sectors, nr_sectors);
|
|
if (!new_io)
|
|
__disk_stat_inc(rq->rq_disk, write_merges);
|
|
}
|
|
if (new_io) {
|
|
disk_round_stats(rq->rq_disk);
|
|
rq->rq_disk->in_flight++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* add-request adds a request to the linked list.
|
|
* queue lock is held and interrupts disabled, as we muck with the
|
|
* request queue list.
|
|
*/
|
|
static inline void add_request(request_queue_t * q, struct request * req)
|
|
{
|
|
drive_stat_acct(req, req->nr_sectors, 1);
|
|
|
|
if (q->activity_fn)
|
|
q->activity_fn(q->activity_data, rq_data_dir(req));
|
|
|
|
/*
|
|
* elevator indicated where it wants this request to be
|
|
* inserted at elevator_merge time
|
|
*/
|
|
__elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
|
|
}
|
|
|
|
/*
|
|
* disk_round_stats() - Round off the performance stats on a struct
|
|
* disk_stats.
|
|
*
|
|
* The average IO queue length and utilisation statistics are maintained
|
|
* by observing the current state of the queue length and the amount of
|
|
* time it has been in this state for.
|
|
*
|
|
* Normally, that accounting is done on IO completion, but that can result
|
|
* in more than a second's worth of IO being accounted for within any one
|
|
* second, leading to >100% utilisation. To deal with that, we call this
|
|
* function to do a round-off before returning the results when reading
|
|
* /proc/diskstats. This accounts immediately for all queue usage up to
|
|
* the current jiffies and restarts the counters again.
|
|
*/
|
|
void disk_round_stats(struct gendisk *disk)
|
|
{
|
|
unsigned long now = jiffies;
|
|
|
|
__disk_stat_add(disk, time_in_queue,
|
|
disk->in_flight * (now - disk->stamp));
|
|
disk->stamp = now;
|
|
|
|
if (disk->in_flight)
|
|
__disk_stat_add(disk, io_ticks, (now - disk->stamp_idle));
|
|
disk->stamp_idle = now;
|
|
}
|
|
|
|
/*
|
|
* queue lock must be held
|
|
*/
|
|
static void __blk_put_request(request_queue_t *q, struct request *req)
|
|
{
|
|
struct request_list *rl = req->rl;
|
|
|
|
if (unlikely(!q))
|
|
return;
|
|
if (unlikely(--req->ref_count))
|
|
return;
|
|
|
|
req->rq_status = RQ_INACTIVE;
|
|
req->rl = NULL;
|
|
|
|
/*
|
|
* Request may not have originated from ll_rw_blk. if not,
|
|
* it didn't come out of our reserved rq pools
|
|
*/
|
|
if (rl) {
|
|
int rw = rq_data_dir(req);
|
|
|
|
elv_completed_request(q, req);
|
|
|
|
BUG_ON(!list_empty(&req->queuelist));
|
|
|
|
blk_free_request(q, req);
|
|
freed_request(q, rw);
|
|
}
|
|
}
|
|
|
|
void blk_put_request(struct request *req)
|
|
{
|
|
/*
|
|
* if req->rl isn't set, this request didnt originate from the
|
|
* block layer, so it's safe to just disregard it
|
|
*/
|
|
if (req->rl) {
|
|
unsigned long flags;
|
|
request_queue_t *q = req->q;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
__blk_put_request(q, req);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_put_request);
|
|
|
|
/**
|
|
* blk_end_sync_rq - executes a completion event on a request
|
|
* @rq: request to complete
|
|
*/
|
|
void blk_end_sync_rq(struct request *rq)
|
|
{
|
|
struct completion *waiting = rq->waiting;
|
|
|
|
rq->waiting = NULL;
|
|
__blk_put_request(rq->q, rq);
|
|
|
|
/*
|
|
* complete last, if this is a stack request the process (and thus
|
|
* the rq pointer) could be invalid right after this complete()
|
|
*/
|
|
complete(waiting);
|
|
}
|
|
EXPORT_SYMBOL(blk_end_sync_rq);
|
|
|
|
/**
|
|
* blk_congestion_wait - wait for a queue to become uncongested
|
|
* @rw: READ or WRITE
|
|
* @timeout: timeout in jiffies
|
|
*
|
|
* Waits for up to @timeout jiffies for a queue (any queue) to exit congestion.
|
|
* If no queues are congested then just wait for the next request to be
|
|
* returned.
|
|
*/
|
|
long blk_congestion_wait(int rw, long timeout)
|
|
{
|
|
long ret;
|
|
DEFINE_WAIT(wait);
|
|
wait_queue_head_t *wqh = &congestion_wqh[rw];
|
|
|
|
prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
|
|
ret = io_schedule_timeout(timeout);
|
|
finish_wait(wqh, &wait);
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_congestion_wait);
|
|
|
|
/*
|
|
* Has to be called with the request spinlock acquired
|
|
*/
|
|
static int attempt_merge(request_queue_t *q, struct request *req,
|
|
struct request *next)
|
|
{
|
|
if (!rq_mergeable(req) || !rq_mergeable(next))
|
|
return 0;
|
|
|
|
/*
|
|
* not contigious
|
|
*/
|
|
if (req->sector + req->nr_sectors != next->sector)
|
|
return 0;
|
|
|
|
if (rq_data_dir(req) != rq_data_dir(next)
|
|
|| req->rq_disk != next->rq_disk
|
|
|| next->waiting || next->special)
|
|
return 0;
|
|
|
|
/*
|
|
* If we are allowed to merge, then append bio list
|
|
* from next to rq and release next. merge_requests_fn
|
|
* will have updated segment counts, update sector
|
|
* counts here.
|
|
*/
|
|
if (!q->merge_requests_fn(q, req, next))
|
|
return 0;
|
|
|
|
/*
|
|
* At this point we have either done a back merge
|
|
* or front merge. We need the smaller start_time of
|
|
* the merged requests to be the current request
|
|
* for accounting purposes.
|
|
*/
|
|
if (time_after(req->start_time, next->start_time))
|
|
req->start_time = next->start_time;
|
|
|
|
req->biotail->bi_next = next->bio;
|
|
req->biotail = next->biotail;
|
|
|
|
req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors;
|
|
|
|
elv_merge_requests(q, req, next);
|
|
|
|
if (req->rq_disk) {
|
|
disk_round_stats(req->rq_disk);
|
|
req->rq_disk->in_flight--;
|
|
}
|
|
|
|
req->ioprio = ioprio_best(req->ioprio, next->ioprio);
|
|
|
|
__blk_put_request(q, next);
|
|
return 1;
|
|
}
|
|
|
|
static inline int attempt_back_merge(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct request *next = elv_latter_request(q, rq);
|
|
|
|
if (next)
|
|
return attempt_merge(q, rq, next);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static inline int attempt_front_merge(request_queue_t *q, struct request *rq)
|
|
{
|
|
struct request *prev = elv_former_request(q, rq);
|
|
|
|
if (prev)
|
|
return attempt_merge(q, prev, rq);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* blk_attempt_remerge - attempt to remerge active head with next request
|
|
* @q: The &request_queue_t belonging to the device
|
|
* @rq: The head request (usually)
|
|
*
|
|
* Description:
|
|
* For head-active devices, the queue can easily be unplugged so quickly
|
|
* that proper merging is not done on the front request. This may hurt
|
|
* performance greatly for some devices. The block layer cannot safely
|
|
* do merging on that first request for these queues, but the driver can
|
|
* call this function and make it happen any way. Only the driver knows
|
|
* when it is safe to do so.
|
|
**/
|
|
void blk_attempt_remerge(request_queue_t *q, struct request *rq)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
attempt_back_merge(q, rq);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_attempt_remerge);
|
|
|
|
static int __make_request(request_queue_t *q, struct bio *bio)
|
|
{
|
|
struct request *req;
|
|
int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err, sync;
|
|
unsigned short prio;
|
|
sector_t sector;
|
|
|
|
sector = bio->bi_sector;
|
|
nr_sectors = bio_sectors(bio);
|
|
cur_nr_sectors = bio_cur_sectors(bio);
|
|
prio = bio_prio(bio);
|
|
|
|
rw = bio_data_dir(bio);
|
|
sync = bio_sync(bio);
|
|
|
|
/*
|
|
* low level driver can indicate that it wants pages above a
|
|
* certain limit bounced to low memory (ie for highmem, or even
|
|
* ISA dma in theory)
|
|
*/
|
|
blk_queue_bounce(q, &bio);
|
|
|
|
spin_lock_prefetch(q->queue_lock);
|
|
|
|
barrier = bio_barrier(bio);
|
|
if (unlikely(barrier) && (q->ordered == QUEUE_ORDERED_NONE)) {
|
|
err = -EOPNOTSUPP;
|
|
goto end_io;
|
|
}
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
if (unlikely(barrier) || elv_queue_empty(q))
|
|
goto get_rq;
|
|
|
|
el_ret = elv_merge(q, &req, bio);
|
|
switch (el_ret) {
|
|
case ELEVATOR_BACK_MERGE:
|
|
BUG_ON(!rq_mergeable(req));
|
|
|
|
if (!q->back_merge_fn(q, req, bio))
|
|
break;
|
|
|
|
req->biotail->bi_next = bio;
|
|
req->biotail = bio;
|
|
req->nr_sectors = req->hard_nr_sectors += nr_sectors;
|
|
req->ioprio = ioprio_best(req->ioprio, prio);
|
|
drive_stat_acct(req, nr_sectors, 0);
|
|
if (!attempt_back_merge(q, req))
|
|
elv_merged_request(q, req);
|
|
goto out;
|
|
|
|
case ELEVATOR_FRONT_MERGE:
|
|
BUG_ON(!rq_mergeable(req));
|
|
|
|
if (!q->front_merge_fn(q, req, bio))
|
|
break;
|
|
|
|
bio->bi_next = req->bio;
|
|
req->bio = bio;
|
|
|
|
/*
|
|
* may not be valid. if the low level driver said
|
|
* it didn't need a bounce buffer then it better
|
|
* not touch req->buffer either...
|
|
*/
|
|
req->buffer = bio_data(bio);
|
|
req->current_nr_sectors = cur_nr_sectors;
|
|
req->hard_cur_sectors = cur_nr_sectors;
|
|
req->sector = req->hard_sector = sector;
|
|
req->nr_sectors = req->hard_nr_sectors += nr_sectors;
|
|
req->ioprio = ioprio_best(req->ioprio, prio);
|
|
drive_stat_acct(req, nr_sectors, 0);
|
|
if (!attempt_front_merge(q, req))
|
|
elv_merged_request(q, req);
|
|
goto out;
|
|
|
|
/* ELV_NO_MERGE: elevator says don't/can't merge. */
|
|
default:
|
|
;
|
|
}
|
|
|
|
get_rq:
|
|
/*
|
|
* Grab a free request. This is might sleep but can not fail.
|
|
* Returns with the queue unlocked.
|
|
*/
|
|
req = get_request_wait(q, rw, bio);
|
|
|
|
/*
|
|
* After dropping the lock and possibly sleeping here, our request
|
|
* may now be mergeable after it had proven unmergeable (above).
|
|
* We don't worry about that case for efficiency. It won't happen
|
|
* often, and the elevators are able to handle it.
|
|
*/
|
|
|
|
req->flags |= REQ_CMD;
|
|
|
|
/*
|
|
* inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
|
|
*/
|
|
if (bio_rw_ahead(bio) || bio_failfast(bio))
|
|
req->flags |= REQ_FAILFAST;
|
|
|
|
/*
|
|
* REQ_BARRIER implies no merging, but lets make it explicit
|
|
*/
|
|
if (unlikely(barrier))
|
|
req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
|
|
|
|
req->errors = 0;
|
|
req->hard_sector = req->sector = sector;
|
|
req->hard_nr_sectors = req->nr_sectors = nr_sectors;
|
|
req->current_nr_sectors = req->hard_cur_sectors = cur_nr_sectors;
|
|
req->nr_phys_segments = bio_phys_segments(q, bio);
|
|
req->nr_hw_segments = bio_hw_segments(q, bio);
|
|
req->buffer = bio_data(bio); /* see ->buffer comment above */
|
|
req->waiting = NULL;
|
|
req->bio = req->biotail = bio;
|
|
req->ioprio = prio;
|
|
req->rq_disk = bio->bi_bdev->bd_disk;
|
|
req->start_time = jiffies;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
if (elv_queue_empty(q))
|
|
blk_plug_device(q);
|
|
add_request(q, req);
|
|
out:
|
|
if (sync)
|
|
__generic_unplug_device(q);
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
return 0;
|
|
|
|
end_io:
|
|
bio_endio(bio, nr_sectors << 9, err);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* If bio->bi_dev is a partition, remap the location
|
|
*/
|
|
static inline void blk_partition_remap(struct bio *bio)
|
|
{
|
|
struct block_device *bdev = bio->bi_bdev;
|
|
|
|
if (bdev != bdev->bd_contains) {
|
|
struct hd_struct *p = bdev->bd_part;
|
|
|
|
switch (bio_data_dir(bio)) {
|
|
case READ:
|
|
p->read_sectors += bio_sectors(bio);
|
|
p->reads++;
|
|
break;
|
|
case WRITE:
|
|
p->write_sectors += bio_sectors(bio);
|
|
p->writes++;
|
|
break;
|
|
}
|
|
bio->bi_sector += p->start_sect;
|
|
bio->bi_bdev = bdev->bd_contains;
|
|
}
|
|
}
|
|
|
|
void blk_finish_queue_drain(request_queue_t *q)
|
|
{
|
|
struct request_list *rl = &q->rq;
|
|
struct request *rq;
|
|
int requeued = 0;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
clear_bit(QUEUE_FLAG_DRAIN, &q->queue_flags);
|
|
|
|
while (!list_empty(&q->drain_list)) {
|
|
rq = list_entry_rq(q->drain_list.next);
|
|
|
|
list_del_init(&rq->queuelist);
|
|
elv_requeue_request(q, rq);
|
|
requeued++;
|
|
}
|
|
|
|
if (requeued)
|
|
q->request_fn(q);
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
wake_up(&rl->wait[0]);
|
|
wake_up(&rl->wait[1]);
|
|
wake_up(&rl->drain);
|
|
}
|
|
|
|
static int wait_drain(request_queue_t *q, struct request_list *rl, int dispatch)
|
|
{
|
|
int wait = rl->count[READ] + rl->count[WRITE];
|
|
|
|
if (dispatch)
|
|
wait += !list_empty(&q->queue_head);
|
|
|
|
return wait;
|
|
}
|
|
|
|
/*
|
|
* We rely on the fact that only requests allocated through blk_alloc_request()
|
|
* have io scheduler private data structures associated with them. Any other
|
|
* type of request (allocated on stack or through kmalloc()) should not go
|
|
* to the io scheduler core, but be attached to the queue head instead.
|
|
*/
|
|
void blk_wait_queue_drained(request_queue_t *q, int wait_dispatch)
|
|
{
|
|
struct request_list *rl = &q->rq;
|
|
DEFINE_WAIT(wait);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
set_bit(QUEUE_FLAG_DRAIN, &q->queue_flags);
|
|
|
|
while (wait_drain(q, rl, wait_dispatch)) {
|
|
prepare_to_wait(&rl->drain, &wait, TASK_UNINTERRUPTIBLE);
|
|
|
|
if (wait_drain(q, rl, wait_dispatch)) {
|
|
__generic_unplug_device(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
io_schedule();
|
|
spin_lock_irq(q->queue_lock);
|
|
}
|
|
|
|
finish_wait(&rl->drain, &wait);
|
|
}
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
|
|
/*
|
|
* block waiting for the io scheduler being started again.
|
|
*/
|
|
static inline void block_wait_queue_running(request_queue_t *q)
|
|
{
|
|
DEFINE_WAIT(wait);
|
|
|
|
while (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags))) {
|
|
struct request_list *rl = &q->rq;
|
|
|
|
prepare_to_wait_exclusive(&rl->drain, &wait,
|
|
TASK_UNINTERRUPTIBLE);
|
|
|
|
/*
|
|
* re-check the condition. avoids using prepare_to_wait()
|
|
* in the fast path (queue is running)
|
|
*/
|
|
if (test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags))
|
|
io_schedule();
|
|
|
|
finish_wait(&rl->drain, &wait);
|
|
}
|
|
}
|
|
|
|
static void handle_bad_sector(struct bio *bio)
|
|
{
|
|
char b[BDEVNAME_SIZE];
|
|
|
|
printk(KERN_INFO "attempt to access beyond end of device\n");
|
|
printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
|
|
bdevname(bio->bi_bdev, b),
|
|
bio->bi_rw,
|
|
(unsigned long long)bio->bi_sector + bio_sectors(bio),
|
|
(long long)(bio->bi_bdev->bd_inode->i_size >> 9));
|
|
|
|
set_bit(BIO_EOF, &bio->bi_flags);
|
|
}
|
|
|
|
/**
|
|
* generic_make_request: hand a buffer to its device driver for I/O
|
|
* @bio: The bio describing the location in memory and on the device.
|
|
*
|
|
* generic_make_request() is used to make I/O requests of block
|
|
* devices. It is passed a &struct bio, which describes the I/O that needs
|
|
* to be done.
|
|
*
|
|
* generic_make_request() does not return any status. The
|
|
* success/failure status of the request, along with notification of
|
|
* completion, is delivered asynchronously through the bio->bi_end_io
|
|
* function described (one day) else where.
|
|
*
|
|
* The caller of generic_make_request must make sure that bi_io_vec
|
|
* are set to describe the memory buffer, and that bi_dev and bi_sector are
|
|
* set to describe the device address, and the
|
|
* bi_end_io and optionally bi_private are set to describe how
|
|
* completion notification should be signaled.
|
|
*
|
|
* generic_make_request and the drivers it calls may use bi_next if this
|
|
* bio happens to be merged with someone else, and may change bi_dev and
|
|
* bi_sector for remaps as it sees fit. So the values of these fields
|
|
* should NOT be depended on after the call to generic_make_request.
|
|
*/
|
|
void generic_make_request(struct bio *bio)
|
|
{
|
|
request_queue_t *q;
|
|
sector_t maxsector;
|
|
int ret, nr_sectors = bio_sectors(bio);
|
|
|
|
might_sleep();
|
|
/* Test device or partition size, when known. */
|
|
maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
|
|
if (maxsector) {
|
|
sector_t sector = bio->bi_sector;
|
|
|
|
if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
|
|
/*
|
|
* This may well happen - the kernel calls bread()
|
|
* without checking the size of the device, e.g., when
|
|
* mounting a device.
|
|
*/
|
|
handle_bad_sector(bio);
|
|
goto end_io;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Resolve the mapping until finished. (drivers are
|
|
* still free to implement/resolve their own stacking
|
|
* by explicitly returning 0)
|
|
*
|
|
* NOTE: we don't repeat the blk_size check for each new device.
|
|
* Stacking drivers are expected to know what they are doing.
|
|
*/
|
|
do {
|
|
char b[BDEVNAME_SIZE];
|
|
|
|
q = bdev_get_queue(bio->bi_bdev);
|
|
if (!q) {
|
|
printk(KERN_ERR
|
|
"generic_make_request: Trying to access "
|
|
"nonexistent block-device %s (%Lu)\n",
|
|
bdevname(bio->bi_bdev, b),
|
|
(long long) bio->bi_sector);
|
|
end_io:
|
|
bio_endio(bio, bio->bi_size, -EIO);
|
|
break;
|
|
}
|
|
|
|
if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) {
|
|
printk("bio too big device %s (%u > %u)\n",
|
|
bdevname(bio->bi_bdev, b),
|
|
bio_sectors(bio),
|
|
q->max_hw_sectors);
|
|
goto end_io;
|
|
}
|
|
|
|
if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
|
|
goto end_io;
|
|
|
|
block_wait_queue_running(q);
|
|
|
|
/*
|
|
* If this device has partitions, remap block n
|
|
* of partition p to block n+start(p) of the disk.
|
|
*/
|
|
blk_partition_remap(bio);
|
|
|
|
ret = q->make_request_fn(q, bio);
|
|
} while (ret);
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_make_request);
|
|
|
|
/**
|
|
* submit_bio: submit a bio to the block device layer for I/O
|
|
* @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
|
|
* @bio: The &struct bio which describes the I/O
|
|
*
|
|
* submit_bio() is very similar in purpose to generic_make_request(), and
|
|
* uses that function to do most of the work. Both are fairly rough
|
|
* interfaces, @bio must be presetup and ready for I/O.
|
|
*
|
|
*/
|
|
void submit_bio(int rw, struct bio *bio)
|
|
{
|
|
int count = bio_sectors(bio);
|
|
|
|
BIO_BUG_ON(!bio->bi_size);
|
|
BIO_BUG_ON(!bio->bi_io_vec);
|
|
bio->bi_rw |= rw;
|
|
if (rw & WRITE)
|
|
mod_page_state(pgpgout, count);
|
|
else
|
|
mod_page_state(pgpgin, count);
|
|
|
|
if (unlikely(block_dump)) {
|
|
char b[BDEVNAME_SIZE];
|
|
printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
|
|
current->comm, current->pid,
|
|
(rw & WRITE) ? "WRITE" : "READ",
|
|
(unsigned long long)bio->bi_sector,
|
|
bdevname(bio->bi_bdev,b));
|
|
}
|
|
|
|
generic_make_request(bio);
|
|
}
|
|
|
|
EXPORT_SYMBOL(submit_bio);
|
|
|
|
static void blk_recalc_rq_segments(struct request *rq)
|
|
{
|
|
struct bio *bio, *prevbio = NULL;
|
|
int nr_phys_segs, nr_hw_segs;
|
|
unsigned int phys_size, hw_size;
|
|
request_queue_t *q = rq->q;
|
|
|
|
if (!rq->bio)
|
|
return;
|
|
|
|
phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
|
|
rq_for_each_bio(bio, rq) {
|
|
/* Force bio hw/phys segs to be recalculated. */
|
|
bio->bi_flags &= ~(1 << BIO_SEG_VALID);
|
|
|
|
nr_phys_segs += bio_phys_segments(q, bio);
|
|
nr_hw_segs += bio_hw_segments(q, bio);
|
|
if (prevbio) {
|
|
int pseg = phys_size + prevbio->bi_size + bio->bi_size;
|
|
int hseg = hw_size + prevbio->bi_size + bio->bi_size;
|
|
|
|
if (blk_phys_contig_segment(q, prevbio, bio) &&
|
|
pseg <= q->max_segment_size) {
|
|
nr_phys_segs--;
|
|
phys_size += prevbio->bi_size + bio->bi_size;
|
|
} else
|
|
phys_size = 0;
|
|
|
|
if (blk_hw_contig_segment(q, prevbio, bio) &&
|
|
hseg <= q->max_segment_size) {
|
|
nr_hw_segs--;
|
|
hw_size += prevbio->bi_size + bio->bi_size;
|
|
} else
|
|
hw_size = 0;
|
|
}
|
|
prevbio = bio;
|
|
}
|
|
|
|
rq->nr_phys_segments = nr_phys_segs;
|
|
rq->nr_hw_segments = nr_hw_segs;
|
|
}
|
|
|
|
static void blk_recalc_rq_sectors(struct request *rq, int nsect)
|
|
{
|
|
if (blk_fs_request(rq)) {
|
|
rq->hard_sector += nsect;
|
|
rq->hard_nr_sectors -= nsect;
|
|
|
|
/*
|
|
* Move the I/O submission pointers ahead if required.
|
|
*/
|
|
if ((rq->nr_sectors >= rq->hard_nr_sectors) &&
|
|
(rq->sector <= rq->hard_sector)) {
|
|
rq->sector = rq->hard_sector;
|
|
rq->nr_sectors = rq->hard_nr_sectors;
|
|
rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
|
|
rq->current_nr_sectors = rq->hard_cur_sectors;
|
|
rq->buffer = bio_data(rq->bio);
|
|
}
|
|
|
|
/*
|
|
* if total number of sectors is less than the first segment
|
|
* size, something has gone terribly wrong
|
|
*/
|
|
if (rq->nr_sectors < rq->current_nr_sectors) {
|
|
printk("blk: request botched\n");
|
|
rq->nr_sectors = rq->current_nr_sectors;
|
|
}
|
|
}
|
|
}
|
|
|
|
static int __end_that_request_first(struct request *req, int uptodate,
|
|
int nr_bytes)
|
|
{
|
|
int total_bytes, bio_nbytes, error, next_idx = 0;
|
|
struct bio *bio;
|
|
|
|
/*
|
|
* extend uptodate bool to allow < 0 value to be direct io error
|
|
*/
|
|
error = 0;
|
|
if (end_io_error(uptodate))
|
|
error = !uptodate ? -EIO : uptodate;
|
|
|
|
/*
|
|
* for a REQ_BLOCK_PC request, we want to carry any eventual
|
|
* sense key with us all the way through
|
|
*/
|
|
if (!blk_pc_request(req))
|
|
req->errors = 0;
|
|
|
|
if (!uptodate) {
|
|
if (blk_fs_request(req) && !(req->flags & REQ_QUIET))
|
|
printk("end_request: I/O error, dev %s, sector %llu\n",
|
|
req->rq_disk ? req->rq_disk->disk_name : "?",
|
|
(unsigned long long)req->sector);
|
|
}
|
|
|
|
total_bytes = bio_nbytes = 0;
|
|
while ((bio = req->bio) != NULL) {
|
|
int nbytes;
|
|
|
|
if (nr_bytes >= bio->bi_size) {
|
|
req->bio = bio->bi_next;
|
|
nbytes = bio->bi_size;
|
|
bio_endio(bio, nbytes, error);
|
|
next_idx = 0;
|
|
bio_nbytes = 0;
|
|
} else {
|
|
int idx = bio->bi_idx + next_idx;
|
|
|
|
if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
|
|
blk_dump_rq_flags(req, "__end_that");
|
|
printk("%s: bio idx %d >= vcnt %d\n",
|
|
__FUNCTION__,
|
|
bio->bi_idx, bio->bi_vcnt);
|
|
break;
|
|
}
|
|
|
|
nbytes = bio_iovec_idx(bio, idx)->bv_len;
|
|
BIO_BUG_ON(nbytes > bio->bi_size);
|
|
|
|
/*
|
|
* not a complete bvec done
|
|
*/
|
|
if (unlikely(nbytes > nr_bytes)) {
|
|
bio_nbytes += nr_bytes;
|
|
total_bytes += nr_bytes;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* advance to the next vector
|
|
*/
|
|
next_idx++;
|
|
bio_nbytes += nbytes;
|
|
}
|
|
|
|
total_bytes += nbytes;
|
|
nr_bytes -= nbytes;
|
|
|
|
if ((bio = req->bio)) {
|
|
/*
|
|
* end more in this run, or just return 'not-done'
|
|
*/
|
|
if (unlikely(nr_bytes <= 0))
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* completely done
|
|
*/
|
|
if (!req->bio)
|
|
return 0;
|
|
|
|
/*
|
|
* if the request wasn't completed, update state
|
|
*/
|
|
if (bio_nbytes) {
|
|
bio_endio(bio, bio_nbytes, error);
|
|
bio->bi_idx += next_idx;
|
|
bio_iovec(bio)->bv_offset += nr_bytes;
|
|
bio_iovec(bio)->bv_len -= nr_bytes;
|
|
}
|
|
|
|
blk_recalc_rq_sectors(req, total_bytes >> 9);
|
|
blk_recalc_rq_segments(req);
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* end_that_request_first - end I/O on a request
|
|
* @req: the request being processed
|
|
* @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
|
|
* @nr_sectors: number of sectors to end I/O on
|
|
*
|
|
* Description:
|
|
* Ends I/O on a number of sectors attached to @req, and sets it up
|
|
* for the next range of segments (if any) in the cluster.
|
|
*
|
|
* Return:
|
|
* 0 - we are done with this request, call end_that_request_last()
|
|
* 1 - still buffers pending for this request
|
|
**/
|
|
int end_that_request_first(struct request *req, int uptodate, int nr_sectors)
|
|
{
|
|
return __end_that_request_first(req, uptodate, nr_sectors << 9);
|
|
}
|
|
|
|
EXPORT_SYMBOL(end_that_request_first);
|
|
|
|
/**
|
|
* end_that_request_chunk - end I/O on a request
|
|
* @req: the request being processed
|
|
* @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
|
|
* @nr_bytes: number of bytes to complete
|
|
*
|
|
* Description:
|
|
* Ends I/O on a number of bytes attached to @req, and sets it up
|
|
* for the next range of segments (if any). Like end_that_request_first(),
|
|
* but deals with bytes instead of sectors.
|
|
*
|
|
* Return:
|
|
* 0 - we are done with this request, call end_that_request_last()
|
|
* 1 - still buffers pending for this request
|
|
**/
|
|
int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes)
|
|
{
|
|
return __end_that_request_first(req, uptodate, nr_bytes);
|
|
}
|
|
|
|
EXPORT_SYMBOL(end_that_request_chunk);
|
|
|
|
/*
|
|
* queue lock must be held
|
|
*/
|
|
void end_that_request_last(struct request *req)
|
|
{
|
|
struct gendisk *disk = req->rq_disk;
|
|
|
|
if (unlikely(laptop_mode) && blk_fs_request(req))
|
|
laptop_io_completion();
|
|
|
|
if (disk && blk_fs_request(req)) {
|
|
unsigned long duration = jiffies - req->start_time;
|
|
switch (rq_data_dir(req)) {
|
|
case WRITE:
|
|
__disk_stat_inc(disk, writes);
|
|
__disk_stat_add(disk, write_ticks, duration);
|
|
break;
|
|
case READ:
|
|
__disk_stat_inc(disk, reads);
|
|
__disk_stat_add(disk, read_ticks, duration);
|
|
break;
|
|
}
|
|
disk_round_stats(disk);
|
|
disk->in_flight--;
|
|
}
|
|
if (req->end_io)
|
|
req->end_io(req);
|
|
else
|
|
__blk_put_request(req->q, req);
|
|
}
|
|
|
|
EXPORT_SYMBOL(end_that_request_last);
|
|
|
|
void end_request(struct request *req, int uptodate)
|
|
{
|
|
if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) {
|
|
add_disk_randomness(req->rq_disk);
|
|
blkdev_dequeue_request(req);
|
|
end_that_request_last(req);
|
|
}
|
|
}
|
|
|
|
EXPORT_SYMBOL(end_request);
|
|
|
|
void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio)
|
|
{
|
|
/* first three bits are identical in rq->flags and bio->bi_rw */
|
|
rq->flags |= (bio->bi_rw & 7);
|
|
|
|
rq->nr_phys_segments = bio_phys_segments(q, bio);
|
|
rq->nr_hw_segments = bio_hw_segments(q, bio);
|
|
rq->current_nr_sectors = bio_cur_sectors(bio);
|
|
rq->hard_cur_sectors = rq->current_nr_sectors;
|
|
rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
|
|
rq->buffer = bio_data(bio);
|
|
|
|
rq->bio = rq->biotail = bio;
|
|
}
|
|
|
|
EXPORT_SYMBOL(blk_rq_bio_prep);
|
|
|
|
int kblockd_schedule_work(struct work_struct *work)
|
|
{
|
|
return queue_work(kblockd_workqueue, work);
|
|
}
|
|
|
|
EXPORT_SYMBOL(kblockd_schedule_work);
|
|
|
|
void kblockd_flush(void)
|
|
{
|
|
flush_workqueue(kblockd_workqueue);
|
|
}
|
|
EXPORT_SYMBOL(kblockd_flush);
|
|
|
|
int __init blk_dev_init(void)
|
|
{
|
|
kblockd_workqueue = create_workqueue("kblockd");
|
|
if (!kblockd_workqueue)
|
|
panic("Failed to create kblockd\n");
|
|
|
|
request_cachep = kmem_cache_create("blkdev_requests",
|
|
sizeof(struct request), 0, SLAB_PANIC, NULL, NULL);
|
|
|
|
requestq_cachep = kmem_cache_create("blkdev_queue",
|
|
sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL);
|
|
|
|
iocontext_cachep = kmem_cache_create("blkdev_ioc",
|
|
sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL);
|
|
|
|
blk_max_low_pfn = max_low_pfn;
|
|
blk_max_pfn = max_pfn;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* IO Context helper functions
|
|
*/
|
|
void put_io_context(struct io_context *ioc)
|
|
{
|
|
if (ioc == NULL)
|
|
return;
|
|
|
|
BUG_ON(atomic_read(&ioc->refcount) == 0);
|
|
|
|
if (atomic_dec_and_test(&ioc->refcount)) {
|
|
if (ioc->aic && ioc->aic->dtor)
|
|
ioc->aic->dtor(ioc->aic);
|
|
if (ioc->cic && ioc->cic->dtor)
|
|
ioc->cic->dtor(ioc->cic);
|
|
|
|
kmem_cache_free(iocontext_cachep, ioc);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(put_io_context);
|
|
|
|
/* Called by the exitting task */
|
|
void exit_io_context(void)
|
|
{
|
|
unsigned long flags;
|
|
struct io_context *ioc;
|
|
|
|
local_irq_save(flags);
|
|
task_lock(current);
|
|
ioc = current->io_context;
|
|
current->io_context = NULL;
|
|
ioc->task = NULL;
|
|
task_unlock(current);
|
|
local_irq_restore(flags);
|
|
|
|
if (ioc->aic && ioc->aic->exit)
|
|
ioc->aic->exit(ioc->aic);
|
|
if (ioc->cic && ioc->cic->exit)
|
|
ioc->cic->exit(ioc->cic);
|
|
|
|
put_io_context(ioc);
|
|
}
|
|
|
|
/*
|
|
* If the current task has no IO context then create one and initialise it.
|
|
* Otherwise, return its existing IO context.
|
|
*
|
|
* This returned IO context doesn't have a specifically elevated refcount,
|
|
* but since the current task itself holds a reference, the context can be
|
|
* used in general code, so long as it stays within `current` context.
|
|
*/
|
|
struct io_context *current_io_context(int gfp_flags)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
struct io_context *ret;
|
|
|
|
ret = tsk->io_context;
|
|
if (likely(ret))
|
|
return ret;
|
|
|
|
ret = kmem_cache_alloc(iocontext_cachep, gfp_flags);
|
|
if (ret) {
|
|
atomic_set(&ret->refcount, 1);
|
|
ret->task = current;
|
|
ret->set_ioprio = NULL;
|
|
ret->last_waited = jiffies; /* doesn't matter... */
|
|
ret->nr_batch_requests = 0; /* because this is 0 */
|
|
ret->aic = NULL;
|
|
ret->cic = NULL;
|
|
tsk->io_context = ret;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(current_io_context);
|
|
|
|
/*
|
|
* If the current task has no IO context then create one and initialise it.
|
|
* If it does have a context, take a ref on it.
|
|
*
|
|
* This is always called in the context of the task which submitted the I/O.
|
|
*/
|
|
struct io_context *get_io_context(int gfp_flags)
|
|
{
|
|
struct io_context *ret;
|
|
ret = current_io_context(gfp_flags);
|
|
if (likely(ret))
|
|
atomic_inc(&ret->refcount);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(get_io_context);
|
|
|
|
void copy_io_context(struct io_context **pdst, struct io_context **psrc)
|
|
{
|
|
struct io_context *src = *psrc;
|
|
struct io_context *dst = *pdst;
|
|
|
|
if (src) {
|
|
BUG_ON(atomic_read(&src->refcount) == 0);
|
|
atomic_inc(&src->refcount);
|
|
put_io_context(dst);
|
|
*pdst = src;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(copy_io_context);
|
|
|
|
void swap_io_context(struct io_context **ioc1, struct io_context **ioc2)
|
|
{
|
|
struct io_context *temp;
|
|
temp = *ioc1;
|
|
*ioc1 = *ioc2;
|
|
*ioc2 = temp;
|
|
}
|
|
EXPORT_SYMBOL(swap_io_context);
|
|
|
|
/*
|
|
* sysfs parts below
|
|
*/
|
|
struct queue_sysfs_entry {
|
|
struct attribute attr;
|
|
ssize_t (*show)(struct request_queue *, char *);
|
|
ssize_t (*store)(struct request_queue *, const char *, size_t);
|
|
};
|
|
|
|
static ssize_t
|
|
queue_var_show(unsigned int var, char *page)
|
|
{
|
|
return sprintf(page, "%d\n", var);
|
|
}
|
|
|
|
static ssize_t
|
|
queue_var_store(unsigned long *var, const char *page, size_t count)
|
|
{
|
|
char *p = (char *) page;
|
|
|
|
*var = simple_strtoul(p, &p, 10);
|
|
return count;
|
|
}
|
|
|
|
static ssize_t queue_requests_show(struct request_queue *q, char *page)
|
|
{
|
|
return queue_var_show(q->nr_requests, (page));
|
|
}
|
|
|
|
static ssize_t
|
|
queue_requests_store(struct request_queue *q, const char *page, size_t count)
|
|
{
|
|
struct request_list *rl = &q->rq;
|
|
|
|
int ret = queue_var_store(&q->nr_requests, page, count);
|
|
if (q->nr_requests < BLKDEV_MIN_RQ)
|
|
q->nr_requests = BLKDEV_MIN_RQ;
|
|
blk_queue_congestion_threshold(q);
|
|
|
|
if (rl->count[READ] >= queue_congestion_on_threshold(q))
|
|
set_queue_congested(q, READ);
|
|
else if (rl->count[READ] < queue_congestion_off_threshold(q))
|
|
clear_queue_congested(q, READ);
|
|
|
|
if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
|
|
set_queue_congested(q, WRITE);
|
|
else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
|
|
clear_queue_congested(q, WRITE);
|
|
|
|
if (rl->count[READ] >= q->nr_requests) {
|
|
blk_set_queue_full(q, READ);
|
|
} else if (rl->count[READ]+1 <= q->nr_requests) {
|
|
blk_clear_queue_full(q, READ);
|
|
wake_up(&rl->wait[READ]);
|
|
}
|
|
|
|
if (rl->count[WRITE] >= q->nr_requests) {
|
|
blk_set_queue_full(q, WRITE);
|
|
} else if (rl->count[WRITE]+1 <= q->nr_requests) {
|
|
blk_clear_queue_full(q, WRITE);
|
|
wake_up(&rl->wait[WRITE]);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t queue_ra_show(struct request_queue *q, char *page)
|
|
{
|
|
int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
|
|
|
|
return queue_var_show(ra_kb, (page));
|
|
}
|
|
|
|
static ssize_t
|
|
queue_ra_store(struct request_queue *q, const char *page, size_t count)
|
|
{
|
|
unsigned long ra_kb;
|
|
ssize_t ret = queue_var_store(&ra_kb, page, count);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
if (ra_kb > (q->max_sectors >> 1))
|
|
ra_kb = (q->max_sectors >> 1);
|
|
|
|
q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
|
|
{
|
|
int max_sectors_kb = q->max_sectors >> 1;
|
|
|
|
return queue_var_show(max_sectors_kb, (page));
|
|
}
|
|
|
|
static ssize_t
|
|
queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
|
|
{
|
|
unsigned long max_sectors_kb,
|
|
max_hw_sectors_kb = q->max_hw_sectors >> 1,
|
|
page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
|
|
ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
|
|
int ra_kb;
|
|
|
|
if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
|
|
return -EINVAL;
|
|
/*
|
|
* Take the queue lock to update the readahead and max_sectors
|
|
* values synchronously:
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
/*
|
|
* Trim readahead window as well, if necessary:
|
|
*/
|
|
ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
|
|
if (ra_kb > max_sectors_kb)
|
|
q->backing_dev_info.ra_pages =
|
|
max_sectors_kb >> (PAGE_CACHE_SHIFT - 10);
|
|
|
|
q->max_sectors = max_sectors_kb << 1;
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
|
|
{
|
|
int max_hw_sectors_kb = q->max_hw_sectors >> 1;
|
|
|
|
return queue_var_show(max_hw_sectors_kb, (page));
|
|
}
|
|
|
|
|
|
static struct queue_sysfs_entry queue_requests_entry = {
|
|
.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
|
|
.show = queue_requests_show,
|
|
.store = queue_requests_store,
|
|
};
|
|
|
|
static struct queue_sysfs_entry queue_ra_entry = {
|
|
.attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
|
|
.show = queue_ra_show,
|
|
.store = queue_ra_store,
|
|
};
|
|
|
|
static struct queue_sysfs_entry queue_max_sectors_entry = {
|
|
.attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
|
|
.show = queue_max_sectors_show,
|
|
.store = queue_max_sectors_store,
|
|
};
|
|
|
|
static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
|
|
.attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
|
|
.show = queue_max_hw_sectors_show,
|
|
};
|
|
|
|
static struct queue_sysfs_entry queue_iosched_entry = {
|
|
.attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
|
|
.show = elv_iosched_show,
|
|
.store = elv_iosched_store,
|
|
};
|
|
|
|
static struct attribute *default_attrs[] = {
|
|
&queue_requests_entry.attr,
|
|
&queue_ra_entry.attr,
|
|
&queue_max_hw_sectors_entry.attr,
|
|
&queue_max_sectors_entry.attr,
|
|
&queue_iosched_entry.attr,
|
|
NULL,
|
|
};
|
|
|
|
#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
|
|
|
|
static ssize_t
|
|
queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
|
|
{
|
|
struct queue_sysfs_entry *entry = to_queue(attr);
|
|
struct request_queue *q;
|
|
|
|
q = container_of(kobj, struct request_queue, kobj);
|
|
if (!entry->show)
|
|
return -EIO;
|
|
|
|
return entry->show(q, page);
|
|
}
|
|
|
|
static ssize_t
|
|
queue_attr_store(struct kobject *kobj, struct attribute *attr,
|
|
const char *page, size_t length)
|
|
{
|
|
struct queue_sysfs_entry *entry = to_queue(attr);
|
|
struct request_queue *q;
|
|
|
|
q = container_of(kobj, struct request_queue, kobj);
|
|
if (!entry->store)
|
|
return -EIO;
|
|
|
|
return entry->store(q, page, length);
|
|
}
|
|
|
|
static struct sysfs_ops queue_sysfs_ops = {
|
|
.show = queue_attr_show,
|
|
.store = queue_attr_store,
|
|
};
|
|
|
|
static struct kobj_type queue_ktype = {
|
|
.sysfs_ops = &queue_sysfs_ops,
|
|
.default_attrs = default_attrs,
|
|
};
|
|
|
|
int blk_register_queue(struct gendisk *disk)
|
|
{
|
|
int ret;
|
|
|
|
request_queue_t *q = disk->queue;
|
|
|
|
if (!q || !q->request_fn)
|
|
return -ENXIO;
|
|
|
|
q->kobj.parent = kobject_get(&disk->kobj);
|
|
if (!q->kobj.parent)
|
|
return -EBUSY;
|
|
|
|
snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue");
|
|
q->kobj.ktype = &queue_ktype;
|
|
|
|
ret = kobject_register(&q->kobj);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
ret = elv_register_queue(q);
|
|
if (ret) {
|
|
kobject_unregister(&q->kobj);
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void blk_unregister_queue(struct gendisk *disk)
|
|
{
|
|
request_queue_t *q = disk->queue;
|
|
|
|
if (q && q->request_fn) {
|
|
elv_unregister_queue(q);
|
|
|
|
kobject_unregister(&q->kobj);
|
|
kobject_put(&disk->kobj);
|
|
}
|
|
}
|