2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics
4 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
5 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
6 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
8 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
12 * This handles all read/write requests to block devices
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/backing-dev.h>
17 #include <linux/bio.h>
18 #include <linux/blkdev.h>
19 #include <linux/highmem.h>
21 #include <linux/kernel_stat.h>
22 #include <linux/string.h>
23 #include <linux/init.h>
24 #include <linux/completion.h>
25 #include <linux/slab.h>
26 #include <linux/swap.h>
27 #include <linux/writeback.h>
28 #include <linux/task_io_accounting_ops.h>
29 #include <linux/blktrace_api.h>
30 #include <linux/fault-inject.h>
34 static int __make_request(struct request_queue *q, struct bio *bio);
37 * For the allocated request tables
39 static struct kmem_cache *request_cachep;
42 * For queue allocation
44 struct kmem_cache *blk_requestq_cachep;
47 * Controlling structure to kblockd
49 static struct workqueue_struct *kblockd_workqueue;
51 static void drive_stat_acct(struct request *rq, int new_io)
53 struct hd_struct *part;
54 int rw = rq_data_dir(rq);
57 if (!blk_fs_request(rq) || !rq->rq_disk)
60 cpu = part_stat_lock();
61 part = disk_map_sector_rcu(rq->rq_disk, rq->sector);
64 part_stat_inc(cpu, part, merges[rw]);
66 part_round_stats(cpu, part);
67 part_inc_in_flight(part);
73 void blk_queue_congestion_threshold(struct request_queue *q)
77 nr = q->nr_requests - (q->nr_requests / 8) + 1;
78 if (nr > q->nr_requests)
80 q->nr_congestion_on = nr;
82 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
85 q->nr_congestion_off = nr;
89 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
92 * Locates the passed device's request queue and returns the address of its
95 * Will return NULL if the request queue cannot be located.
97 struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
99 struct backing_dev_info *ret = NULL;
100 struct request_queue *q = bdev_get_queue(bdev);
103 ret = &q->backing_dev_info;
106 EXPORT_SYMBOL(blk_get_backing_dev_info);
108 void blk_rq_init(struct request_queue *q, struct request *rq)
110 memset(rq, 0, sizeof(*rq));
112 INIT_LIST_HEAD(&rq->queuelist);
113 INIT_LIST_HEAD(&rq->timeout_list);
116 rq->sector = rq->hard_sector = (sector_t) -1;
117 INIT_HLIST_NODE(&rq->hash);
118 RB_CLEAR_NODE(&rq->rb_node);
123 EXPORT_SYMBOL(blk_rq_init);
125 static void req_bio_endio(struct request *rq, struct bio *bio,
126 unsigned int nbytes, int error)
128 struct request_queue *q = rq->q;
130 if (&q->bar_rq != rq) {
132 clear_bit(BIO_UPTODATE, &bio->bi_flags);
133 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
136 if (unlikely(nbytes > bio->bi_size)) {
137 printk(KERN_ERR "%s: want %u bytes done, %u left\n",
138 __func__, nbytes, bio->bi_size);
139 nbytes = bio->bi_size;
142 bio->bi_size -= nbytes;
143 bio->bi_sector += (nbytes >> 9);
145 if (bio_integrity(bio))
146 bio_integrity_advance(bio, nbytes);
148 if (bio->bi_size == 0)
149 bio_endio(bio, error);
153 * Okay, this is the barrier request in progress, just
156 if (error && !q->orderr)
161 void blk_dump_rq_flags(struct request *rq, char *msg)
165 printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg,
166 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
169 printk(KERN_INFO " sector %llu, nr/cnr %lu/%u\n",
170 (unsigned long long)rq->sector,
172 rq->current_nr_sectors);
173 printk(KERN_INFO " bio %p, biotail %p, buffer %p, data %p, len %u\n",
174 rq->bio, rq->biotail,
175 rq->buffer, rq->data,
178 if (blk_pc_request(rq)) {
179 printk(KERN_INFO " cdb: ");
180 for (bit = 0; bit < BLK_MAX_CDB; bit++)
181 printk("%02x ", rq->cmd[bit]);
185 EXPORT_SYMBOL(blk_dump_rq_flags);
188 * "plug" the device if there are no outstanding requests: this will
189 * force the transfer to start only after we have put all the requests
192 * This is called with interrupts off and no requests on the queue and
193 * with the queue lock held.
195 void blk_plug_device(struct request_queue *q)
197 WARN_ON(!irqs_disabled());
200 * don't plug a stopped queue, it must be paired with blk_start_queue()
201 * which will restart the queueing
203 if (blk_queue_stopped(q))
206 if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) {
207 mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
208 blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
211 EXPORT_SYMBOL(blk_plug_device);
214 * blk_plug_device_unlocked - plug a device without queue lock held
215 * @q: The &struct request_queue to plug
218 * Like @blk_plug_device(), but grabs the queue lock and disables
221 void blk_plug_device_unlocked(struct request_queue *q)
225 spin_lock_irqsave(q->queue_lock, flags);
227 spin_unlock_irqrestore(q->queue_lock, flags);
229 EXPORT_SYMBOL(blk_plug_device_unlocked);
232 * remove the queue from the plugged list, if present. called with
233 * queue lock held and interrupts disabled.
235 int blk_remove_plug(struct request_queue *q)
237 WARN_ON(!irqs_disabled());
239 if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q))
242 del_timer(&q->unplug_timer);
245 EXPORT_SYMBOL(blk_remove_plug);
248 * remove the plug and let it rip..
250 void __generic_unplug_device(struct request_queue *q)
252 if (unlikely(blk_queue_stopped(q)))
255 if (!blk_remove_plug(q))
260 EXPORT_SYMBOL(__generic_unplug_device);
263 * generic_unplug_device - fire a request queue
264 * @q: The &struct request_queue in question
267 * Linux uses plugging to build bigger requests queues before letting
268 * the device have at them. If a queue is plugged, the I/O scheduler
269 * is still adding and merging requests on the queue. Once the queue
270 * gets unplugged, the request_fn defined for the queue is invoked and
273 void generic_unplug_device(struct request_queue *q)
275 if (blk_queue_plugged(q)) {
276 spin_lock_irq(q->queue_lock);
277 __generic_unplug_device(q);
278 spin_unlock_irq(q->queue_lock);
281 EXPORT_SYMBOL(generic_unplug_device);
283 static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
286 struct request_queue *q = bdi->unplug_io_data;
291 void blk_unplug_work(struct work_struct *work)
293 struct request_queue *q =
294 container_of(work, struct request_queue, unplug_work);
296 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
297 q->rq.count[READ] + q->rq.count[WRITE]);
302 void blk_unplug_timeout(unsigned long data)
304 struct request_queue *q = (struct request_queue *)data;
306 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL,
307 q->rq.count[READ] + q->rq.count[WRITE]);
309 kblockd_schedule_work(q, &q->unplug_work);
312 void blk_unplug(struct request_queue *q)
315 * devices don't necessarily have an ->unplug_fn defined
318 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
319 q->rq.count[READ] + q->rq.count[WRITE]);
324 EXPORT_SYMBOL(blk_unplug);
326 static void blk_invoke_request_fn(struct request_queue *q)
329 * one level of recursion is ok and is much faster than kicking
330 * the unplug handling
332 if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
334 queue_flag_clear(QUEUE_FLAG_REENTER, q);
336 queue_flag_set(QUEUE_FLAG_PLUGGED, q);
337 kblockd_schedule_work(q, &q->unplug_work);
342 * blk_start_queue - restart a previously stopped queue
343 * @q: The &struct request_queue in question
346 * blk_start_queue() will clear the stop flag on the queue, and call
347 * the request_fn for the queue if it was in a stopped state when
348 * entered. Also see blk_stop_queue(). Queue lock must be held.
350 void blk_start_queue(struct request_queue *q)
352 WARN_ON(!irqs_disabled());
354 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
355 blk_invoke_request_fn(q);
357 EXPORT_SYMBOL(blk_start_queue);
360 * blk_stop_queue - stop a queue
361 * @q: The &struct request_queue in question
364 * The Linux block layer assumes that a block driver will consume all
365 * entries on the request queue when the request_fn strategy is called.
366 * Often this will not happen, because of hardware limitations (queue
367 * depth settings). If a device driver gets a 'queue full' response,
368 * or if it simply chooses not to queue more I/O at one point, it can
369 * call this function to prevent the request_fn from being called until
370 * the driver has signalled it's ready to go again. This happens by calling
371 * blk_start_queue() to restart queue operations. Queue lock must be held.
373 void blk_stop_queue(struct request_queue *q)
376 queue_flag_set(QUEUE_FLAG_STOPPED, q);
378 EXPORT_SYMBOL(blk_stop_queue);
381 * blk_sync_queue - cancel any pending callbacks on a queue
385 * The block layer may perform asynchronous callback activity
386 * on a queue, such as calling the unplug function after a timeout.
387 * A block device may call blk_sync_queue to ensure that any
388 * such activity is cancelled, thus allowing it to release resources
389 * that the callbacks might use. The caller must already have made sure
390 * that its ->make_request_fn will not re-add plugging prior to calling
394 void blk_sync_queue(struct request_queue *q)
396 del_timer_sync(&q->unplug_timer);
397 kblockd_flush_work(&q->unplug_work);
399 EXPORT_SYMBOL(blk_sync_queue);
402 * blk_run_queue - run a single device queue
403 * @q: The queue to run
405 void __blk_run_queue(struct request_queue *q)
410 * Only recurse once to avoid overrunning the stack, let the unplug
411 * handling reinvoke the handler shortly if we already got there.
413 if (!elv_queue_empty(q))
414 blk_invoke_request_fn(q);
416 EXPORT_SYMBOL(__blk_run_queue);
419 * blk_run_queue - run a single device queue
420 * @q: The queue to run
422 void blk_run_queue(struct request_queue *q)
426 spin_lock_irqsave(q->queue_lock, flags);
428 spin_unlock_irqrestore(q->queue_lock, flags);
430 EXPORT_SYMBOL(blk_run_queue);
432 void blk_put_queue(struct request_queue *q)
434 kobject_put(&q->kobj);
437 void blk_cleanup_queue(struct request_queue *q)
440 * We know we have process context here, so we can be a little
441 * cautious and ensure that pending block actions on this device
442 * are done before moving on. Going into this function, we should
443 * not have processes doing IO to this device.
447 mutex_lock(&q->sysfs_lock);
448 queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
449 mutex_unlock(&q->sysfs_lock);
452 elevator_exit(q->elevator);
456 EXPORT_SYMBOL(blk_cleanup_queue);
458 static int blk_init_free_list(struct request_queue *q)
460 struct request_list *rl = &q->rq;
462 rl->count[READ] = rl->count[WRITE] = 0;
463 rl->starved[READ] = rl->starved[WRITE] = 0;
465 init_waitqueue_head(&rl->wait[READ]);
466 init_waitqueue_head(&rl->wait[WRITE]);
468 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
469 mempool_free_slab, request_cachep, q->node);
477 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
479 return blk_alloc_queue_node(gfp_mask, -1);
481 EXPORT_SYMBOL(blk_alloc_queue);
483 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
485 struct request_queue *q;
488 q = kmem_cache_alloc_node(blk_requestq_cachep,
489 gfp_mask | __GFP_ZERO, node_id);
493 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
494 q->backing_dev_info.unplug_io_data = q;
495 err = bdi_init(&q->backing_dev_info);
497 kmem_cache_free(blk_requestq_cachep, q);
501 init_timer(&q->unplug_timer);
502 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
503 INIT_LIST_HEAD(&q->timeout_list);
505 kobject_init(&q->kobj, &blk_queue_ktype);
507 mutex_init(&q->sysfs_lock);
508 spin_lock_init(&q->__queue_lock);
512 EXPORT_SYMBOL(blk_alloc_queue_node);
515 * blk_init_queue - prepare a request queue for use with a block device
516 * @rfn: The function to be called to process requests that have been
517 * placed on the queue.
518 * @lock: Request queue spin lock
521 * If a block device wishes to use the standard request handling procedures,
522 * which sorts requests and coalesces adjacent requests, then it must
523 * call blk_init_queue(). The function @rfn will be called when there
524 * are requests on the queue that need to be processed. If the device
525 * supports plugging, then @rfn may not be called immediately when requests
526 * are available on the queue, but may be called at some time later instead.
527 * Plugged queues are generally unplugged when a buffer belonging to one
528 * of the requests on the queue is needed, or due to memory pressure.
530 * @rfn is not required, or even expected, to remove all requests off the
531 * queue, but only as many as it can handle at a time. If it does leave
532 * requests on the queue, it is responsible for arranging that the requests
533 * get dealt with eventually.
535 * The queue spin lock must be held while manipulating the requests on the
536 * request queue; this lock will be taken also from interrupt context, so irq
537 * disabling is needed for it.
539 * Function returns a pointer to the initialized request queue, or %NULL if
543 * blk_init_queue() must be paired with a blk_cleanup_queue() call
544 * when the block device is deactivated (such as at module unload).
547 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
549 return blk_init_queue_node(rfn, lock, -1);
551 EXPORT_SYMBOL(blk_init_queue);
553 struct request_queue *
554 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
556 struct request_queue *q = blk_alloc_queue_node(GFP_KERNEL, node_id);
562 if (blk_init_free_list(q)) {
563 kmem_cache_free(blk_requestq_cachep, q);
568 * if caller didn't supply a lock, they get per-queue locking with
572 lock = &q->__queue_lock;
575 q->prep_rq_fn = NULL;
576 q->unplug_fn = generic_unplug_device;
577 q->queue_flags = (1 << QUEUE_FLAG_CLUSTER |
578 1 << QUEUE_FLAG_STACKABLE);
579 q->queue_lock = lock;
581 blk_queue_segment_boundary(q, 0xffffffff);
583 blk_queue_make_request(q, __make_request);
584 blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
586 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
587 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
589 q->sg_reserved_size = INT_MAX;
591 blk_set_cmd_filter_defaults(&q->cmd_filter);
596 if (!elevator_init(q, NULL)) {
597 blk_queue_congestion_threshold(q);
604 EXPORT_SYMBOL(blk_init_queue_node);
606 int blk_get_queue(struct request_queue *q)
608 if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
609 kobject_get(&q->kobj);
616 static inline void blk_free_request(struct request_queue *q, struct request *rq)
618 if (rq->cmd_flags & REQ_ELVPRIV)
619 elv_put_request(q, rq);
620 mempool_free(rq, q->rq.rq_pool);
623 static struct request *
624 blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask)
626 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
633 rq->cmd_flags = rw | REQ_ALLOCED;
636 if (unlikely(elv_set_request(q, rq, gfp_mask))) {
637 mempool_free(rq, q->rq.rq_pool);
640 rq->cmd_flags |= REQ_ELVPRIV;
647 * ioc_batching returns true if the ioc is a valid batching request and
648 * should be given priority access to a request.
650 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
656 * Make sure the process is able to allocate at least 1 request
657 * even if the batch times out, otherwise we could theoretically
660 return ioc->nr_batch_requests == q->nr_batching ||
661 (ioc->nr_batch_requests > 0
662 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
666 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
667 * will cause the process to be a "batcher" on all queues in the system. This
668 * is the behaviour we want though - once it gets a wakeup it should be given
671 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
673 if (!ioc || ioc_batching(q, ioc))
676 ioc->nr_batch_requests = q->nr_batching;
677 ioc->last_waited = jiffies;
680 static void __freed_request(struct request_queue *q, int rw)
682 struct request_list *rl = &q->rq;
684 if (rl->count[rw] < queue_congestion_off_threshold(q))
685 blk_clear_queue_congested(q, rw);
687 if (rl->count[rw] + 1 <= q->nr_requests) {
688 if (waitqueue_active(&rl->wait[rw]))
689 wake_up(&rl->wait[rw]);
691 blk_clear_queue_full(q, rw);
696 * A request has just been released. Account for it, update the full and
697 * congestion status, wake up any waiters. Called under q->queue_lock.
699 static void freed_request(struct request_queue *q, int rw, int priv)
701 struct request_list *rl = &q->rq;
707 __freed_request(q, rw);
709 if (unlikely(rl->starved[rw ^ 1]))
710 __freed_request(q, rw ^ 1);
713 #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
715 * Get a free request, queue_lock must be held.
716 * Returns NULL on failure, with queue_lock held.
717 * Returns !NULL on success, with queue_lock *not held*.
719 static struct request *get_request(struct request_queue *q, int rw_flags,
720 struct bio *bio, gfp_t gfp_mask)
722 struct request *rq = NULL;
723 struct request_list *rl = &q->rq;
724 struct io_context *ioc = NULL;
725 const int rw = rw_flags & 0x01;
728 may_queue = elv_may_queue(q, rw_flags);
729 if (may_queue == ELV_MQUEUE_NO)
732 if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
733 if (rl->count[rw]+1 >= q->nr_requests) {
734 ioc = current_io_context(GFP_ATOMIC, q->node);
736 * The queue will fill after this allocation, so set
737 * it as full, and mark this process as "batching".
738 * This process will be allowed to complete a batch of
739 * requests, others will be blocked.
741 if (!blk_queue_full(q, rw)) {
742 ioc_set_batching(q, ioc);
743 blk_set_queue_full(q, rw);
745 if (may_queue != ELV_MQUEUE_MUST
746 && !ioc_batching(q, ioc)) {
748 * The queue is full and the allocating
749 * process is not a "batcher", and not
750 * exempted by the IO scheduler
756 blk_set_queue_congested(q, rw);
760 * Only allow batching queuers to allocate up to 50% over the defined
761 * limit of requests, otherwise we could have thousands of requests
762 * allocated with any setting of ->nr_requests
764 if (rl->count[rw] >= (3 * q->nr_requests / 2))
770 priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
774 spin_unlock_irq(q->queue_lock);
776 rq = blk_alloc_request(q, rw_flags, priv, gfp_mask);
779 * Allocation failed presumably due to memory. Undo anything
780 * we might have messed up.
782 * Allocating task should really be put onto the front of the
783 * wait queue, but this is pretty rare.
785 spin_lock_irq(q->queue_lock);
786 freed_request(q, rw, priv);
789 * in the very unlikely event that allocation failed and no
790 * requests for this direction was pending, mark us starved
791 * so that freeing of a request in the other direction will
792 * notice us. another possible fix would be to split the
793 * rq mempool into READ and WRITE
796 if (unlikely(rl->count[rw] == 0))
803 * ioc may be NULL here, and ioc_batching will be false. That's
804 * OK, if the queue is under the request limit then requests need
805 * not count toward the nr_batch_requests limit. There will always
806 * be some limit enforced by BLK_BATCH_TIME.
808 if (ioc_batching(q, ioc))
809 ioc->nr_batch_requests--;
811 blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ);
817 * No available requests for this queue, unplug the device and wait for some
818 * requests to become available.
820 * Called with q->queue_lock held, and returns with it unlocked.
822 static struct request *get_request_wait(struct request_queue *q, int rw_flags,
825 const int rw = rw_flags & 0x01;
828 rq = get_request(q, rw_flags, bio, GFP_NOIO);
831 struct io_context *ioc;
832 struct request_list *rl = &q->rq;
834 prepare_to_wait_exclusive(&rl->wait[rw], &wait,
835 TASK_UNINTERRUPTIBLE);
837 blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
839 __generic_unplug_device(q);
840 spin_unlock_irq(q->queue_lock);
844 * After sleeping, we become a "batching" process and
845 * will be able to allocate at least one request, and
846 * up to a big batch of them for a small period time.
847 * See ioc_batching, ioc_set_batching
849 ioc = current_io_context(GFP_NOIO, q->node);
850 ioc_set_batching(q, ioc);
852 spin_lock_irq(q->queue_lock);
853 finish_wait(&rl->wait[rw], &wait);
855 rq = get_request(q, rw_flags, bio, GFP_NOIO);
861 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
865 BUG_ON(rw != READ && rw != WRITE);
867 spin_lock_irq(q->queue_lock);
868 if (gfp_mask & __GFP_WAIT) {
869 rq = get_request_wait(q, rw, NULL);
871 rq = get_request(q, rw, NULL, gfp_mask);
873 spin_unlock_irq(q->queue_lock);
875 /* q->queue_lock is unlocked at this point */
879 EXPORT_SYMBOL(blk_get_request);
882 * blk_start_queueing - initiate dispatch of requests to device
883 * @q: request queue to kick into gear
885 * This is basically a helper to remove the need to know whether a queue
886 * is plugged or not if someone just wants to initiate dispatch of requests
889 * The queue lock must be held with interrupts disabled.
891 void blk_start_queueing(struct request_queue *q)
893 if (!blk_queue_plugged(q))
896 __generic_unplug_device(q);
898 EXPORT_SYMBOL(blk_start_queueing);
901 * blk_requeue_request - put a request back on queue
902 * @q: request queue where request should be inserted
903 * @rq: request to be inserted
906 * Drivers often keep queueing requests until the hardware cannot accept
907 * more, when that condition happens we need to put the request back
908 * on the queue. Must be called with queue lock held.
910 void blk_requeue_request(struct request_queue *q, struct request *rq)
912 blk_delete_timer(rq);
913 blk_clear_rq_complete(rq);
914 blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
916 if (blk_rq_tagged(rq))
917 blk_queue_end_tag(q, rq);
919 elv_requeue_request(q, rq);
921 EXPORT_SYMBOL(blk_requeue_request);
924 * blk_insert_request - insert a special request into a request queue
925 * @q: request queue where request should be inserted
926 * @rq: request to be inserted
927 * @at_head: insert request at head or tail of queue
928 * @data: private data
931 * Many block devices need to execute commands asynchronously, so they don't
932 * block the whole kernel from preemption during request execution. This is
933 * accomplished normally by inserting aritficial requests tagged as
934 * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them
935 * be scheduled for actual execution by the request queue.
937 * We have the option of inserting the head or the tail of the queue.
938 * Typically we use the tail for new ioctls and so forth. We use the head
939 * of the queue for things like a QUEUE_FULL message from a device, or a
940 * host that is unable to accept a particular command.
942 void blk_insert_request(struct request_queue *q, struct request *rq,
943 int at_head, void *data)
945 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
949 * tell I/O scheduler that this isn't a regular read/write (ie it
950 * must not attempt merges on this) and that it acts as a soft
953 rq->cmd_type = REQ_TYPE_SPECIAL;
954 rq->cmd_flags |= REQ_SOFTBARRIER;
958 spin_lock_irqsave(q->queue_lock, flags);
961 * If command is tagged, release the tag
963 if (blk_rq_tagged(rq))
964 blk_queue_end_tag(q, rq);
966 drive_stat_acct(rq, 1);
967 __elv_add_request(q, rq, where, 0);
968 blk_start_queueing(q);
969 spin_unlock_irqrestore(q->queue_lock, flags);
971 EXPORT_SYMBOL(blk_insert_request);
974 * add-request adds a request to the linked list.
975 * queue lock is held and interrupts disabled, as we muck with the
976 * request queue list.
978 static inline void add_request(struct request_queue *q, struct request *req)
980 drive_stat_acct(req, 1);
983 * elevator indicated where it wants this request to be
984 * inserted at elevator_merge time
986 __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
989 static void part_round_stats_single(int cpu, struct hd_struct *part,
992 if (now == part->stamp)
995 if (part->in_flight) {
996 __part_stat_add(cpu, part, time_in_queue,
997 part->in_flight * (now - part->stamp));
998 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1004 * part_round_stats() - Round off the performance stats on a struct
1007 * The average IO queue length and utilisation statistics are maintained
1008 * by observing the current state of the queue length and the amount of
1009 * time it has been in this state for.
1011 * Normally, that accounting is done on IO completion, but that can result
1012 * in more than a second's worth of IO being accounted for within any one
1013 * second, leading to >100% utilisation. To deal with that, we call this
1014 * function to do a round-off before returning the results when reading
1015 * /proc/diskstats. This accounts immediately for all queue usage up to
1016 * the current jiffies and restarts the counters again.
1018 void part_round_stats(int cpu, struct hd_struct *part)
1020 unsigned long now = jiffies;
1023 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1024 part_round_stats_single(cpu, part, now);
1026 EXPORT_SYMBOL_GPL(part_round_stats);
1029 * queue lock must be held
1031 void __blk_put_request(struct request_queue *q, struct request *req)
1035 if (unlikely(--req->ref_count))
1038 elv_completed_request(q, req);
1041 * Request may not have originated from ll_rw_blk. if not,
1042 * it didn't come out of our reserved rq pools
1044 if (req->cmd_flags & REQ_ALLOCED) {
1045 int rw = rq_data_dir(req);
1046 int priv = req->cmd_flags & REQ_ELVPRIV;
1048 BUG_ON(!list_empty(&req->queuelist));
1049 BUG_ON(!hlist_unhashed(&req->hash));
1051 blk_free_request(q, req);
1052 freed_request(q, rw, priv);
1055 EXPORT_SYMBOL_GPL(__blk_put_request);
1057 void blk_put_request(struct request *req)
1059 unsigned long flags;
1060 struct request_queue *q = req->q;
1062 spin_lock_irqsave(q->queue_lock, flags);
1063 __blk_put_request(q, req);
1064 spin_unlock_irqrestore(q->queue_lock, flags);
1066 EXPORT_SYMBOL(blk_put_request);
1068 void init_request_from_bio(struct request *req, struct bio *bio)
1070 req->cpu = bio->bi_comp_cpu;
1071 req->cmd_type = REQ_TYPE_FS;
1074 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
1076 if (bio_rw_ahead(bio) || bio_failfast(bio))
1077 req->cmd_flags |= REQ_FAILFAST;
1080 * REQ_BARRIER implies no merging, but lets make it explicit
1082 if (unlikely(bio_discard(bio))) {
1083 req->cmd_flags |= REQ_DISCARD;
1084 if (bio_barrier(bio))
1085 req->cmd_flags |= REQ_SOFTBARRIER;
1086 req->q->prepare_discard_fn(req->q, req);
1087 } else if (unlikely(bio_barrier(bio)))
1088 req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
1091 req->cmd_flags |= REQ_RW_SYNC;
1092 if (bio_rw_meta(bio))
1093 req->cmd_flags |= REQ_RW_META;
1096 req->hard_sector = req->sector = bio->bi_sector;
1097 req->ioprio = bio_prio(bio);
1098 req->start_time = jiffies;
1099 blk_rq_bio_prep(req->q, req, bio);
1102 static int __make_request(struct request_queue *q, struct bio *bio)
1104 struct request *req;
1105 int el_ret, nr_sectors, barrier, discard, err;
1106 const unsigned short prio = bio_prio(bio);
1107 const int sync = bio_sync(bio);
1110 nr_sectors = bio_sectors(bio);
1113 * low level driver can indicate that it wants pages above a
1114 * certain limit bounced to low memory (ie for highmem, or even
1115 * ISA dma in theory)
1117 blk_queue_bounce(q, &bio);
1119 barrier = bio_barrier(bio);
1120 if (unlikely(barrier) && bio_has_data(bio) &&
1121 (q->next_ordered == QUEUE_ORDERED_NONE)) {
1126 discard = bio_discard(bio);
1127 if (unlikely(discard) && !q->prepare_discard_fn) {
1132 spin_lock_irq(q->queue_lock);
1134 if (unlikely(barrier) || elv_queue_empty(q))
1137 el_ret = elv_merge(q, &req, bio);
1139 case ELEVATOR_BACK_MERGE:
1140 BUG_ON(!rq_mergeable(req));
1142 if (!ll_back_merge_fn(q, req, bio))
1145 blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
1147 req->biotail->bi_next = bio;
1149 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
1150 req->ioprio = ioprio_best(req->ioprio, prio);
1151 if (!blk_rq_cpu_valid(req))
1152 req->cpu = bio->bi_comp_cpu;
1153 drive_stat_acct(req, 0);
1154 if (!attempt_back_merge(q, req))
1155 elv_merged_request(q, req, el_ret);
1158 case ELEVATOR_FRONT_MERGE:
1159 BUG_ON(!rq_mergeable(req));
1161 if (!ll_front_merge_fn(q, req, bio))
1164 blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
1166 bio->bi_next = req->bio;
1170 * may not be valid. if the low level driver said
1171 * it didn't need a bounce buffer then it better
1172 * not touch req->buffer either...
1174 req->buffer = bio_data(bio);
1175 req->current_nr_sectors = bio_cur_sectors(bio);
1176 req->hard_cur_sectors = req->current_nr_sectors;
1177 req->sector = req->hard_sector = bio->bi_sector;
1178 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
1179 req->ioprio = ioprio_best(req->ioprio, prio);
1180 if (!blk_rq_cpu_valid(req))
1181 req->cpu = bio->bi_comp_cpu;
1182 drive_stat_acct(req, 0);
1183 if (!attempt_front_merge(q, req))
1184 elv_merged_request(q, req, el_ret);
1187 /* ELV_NO_MERGE: elevator says don't/can't merge. */
1194 * This sync check and mask will be re-done in init_request_from_bio(),
1195 * but we need to set it earlier to expose the sync flag to the
1196 * rq allocator and io schedulers.
1198 rw_flags = bio_data_dir(bio);
1200 rw_flags |= REQ_RW_SYNC;
1203 * Grab a free request. This is might sleep but can not fail.
1204 * Returns with the queue unlocked.
1206 req = get_request_wait(q, rw_flags, bio);
1209 * After dropping the lock and possibly sleeping here, our request
1210 * may now be mergeable after it had proven unmergeable (above).
1211 * We don't worry about that case for efficiency. It won't happen
1212 * often, and the elevators are able to handle it.
1214 init_request_from_bio(req, bio);
1216 spin_lock_irq(q->queue_lock);
1217 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) ||
1218 bio_flagged(bio, BIO_CPU_AFFINE))
1219 req->cpu = blk_cpu_to_group(smp_processor_id());
1220 if (elv_queue_empty(q))
1222 add_request(q, req);
1225 __generic_unplug_device(q);
1226 spin_unlock_irq(q->queue_lock);
1230 bio_endio(bio, err);
1235 * If bio->bi_dev is a partition, remap the location
1237 static inline void blk_partition_remap(struct bio *bio)
1239 struct block_device *bdev = bio->bi_bdev;
1241 if (bio_sectors(bio) && bdev != bdev->bd_contains) {
1242 struct hd_struct *p = bdev->bd_part;
1244 bio->bi_sector += p->start_sect;
1245 bio->bi_bdev = bdev->bd_contains;
1247 blk_add_trace_remap(bdev_get_queue(bio->bi_bdev), bio,
1248 bdev->bd_dev, bio->bi_sector,
1249 bio->bi_sector - p->start_sect);
1253 static void handle_bad_sector(struct bio *bio)
1255 char b[BDEVNAME_SIZE];
1257 printk(KERN_INFO "attempt to access beyond end of device\n");
1258 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1259 bdevname(bio->bi_bdev, b),
1261 (unsigned long long)bio->bi_sector + bio_sectors(bio),
1262 (long long)(bio->bi_bdev->bd_inode->i_size >> 9));
1264 set_bit(BIO_EOF, &bio->bi_flags);
1267 #ifdef CONFIG_FAIL_MAKE_REQUEST
1269 static DECLARE_FAULT_ATTR(fail_make_request);
1271 static int __init setup_fail_make_request(char *str)
1273 return setup_fault_attr(&fail_make_request, str);
1275 __setup("fail_make_request=", setup_fail_make_request);
1277 static int should_fail_request(struct bio *bio)
1279 struct hd_struct *part = bio->bi_bdev->bd_part;
1281 if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail)
1282 return should_fail(&fail_make_request, bio->bi_size);
1287 static int __init fail_make_request_debugfs(void)
1289 return init_fault_attr_dentries(&fail_make_request,
1290 "fail_make_request");
1293 late_initcall(fail_make_request_debugfs);
1295 #else /* CONFIG_FAIL_MAKE_REQUEST */
1297 static inline int should_fail_request(struct bio *bio)
1302 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1305 * Check whether this bio extends beyond the end of the device.
1307 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1314 /* Test device or partition size, when known. */
1315 maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
1317 sector_t sector = bio->bi_sector;
1319 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1321 * This may well happen - the kernel calls bread()
1322 * without checking the size of the device, e.g., when
1323 * mounting a device.
1325 handle_bad_sector(bio);
1334 * generic_make_request - hand a buffer to its device driver for I/O
1335 * @bio: The bio describing the location in memory and on the device.
1337 * generic_make_request() is used to make I/O requests of block
1338 * devices. It is passed a &struct bio, which describes the I/O that needs
1341 * generic_make_request() does not return any status. The
1342 * success/failure status of the request, along with notification of
1343 * completion, is delivered asynchronously through the bio->bi_end_io
1344 * function described (one day) else where.
1346 * The caller of generic_make_request must make sure that bi_io_vec
1347 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1348 * set to describe the device address, and the
1349 * bi_end_io and optionally bi_private are set to describe how
1350 * completion notification should be signaled.
1352 * generic_make_request and the drivers it calls may use bi_next if this
1353 * bio happens to be merged with someone else, and may change bi_dev and
1354 * bi_sector for remaps as it sees fit. So the values of these fields
1355 * should NOT be depended on after the call to generic_make_request.
1357 static inline void __generic_make_request(struct bio *bio)
1359 struct request_queue *q;
1360 sector_t old_sector;
1361 int ret, nr_sectors = bio_sectors(bio);
1367 if (bio_check_eod(bio, nr_sectors))
1371 * Resolve the mapping until finished. (drivers are
1372 * still free to implement/resolve their own stacking
1373 * by explicitly returning 0)
1375 * NOTE: we don't repeat the blk_size check for each new device.
1376 * Stacking drivers are expected to know what they are doing.
1381 char b[BDEVNAME_SIZE];
1383 q = bdev_get_queue(bio->bi_bdev);
1386 "generic_make_request: Trying to access "
1387 "nonexistent block-device %s (%Lu)\n",
1388 bdevname(bio->bi_bdev, b),
1389 (long long) bio->bi_sector);
1391 bio_endio(bio, err);
1395 if (unlikely(nr_sectors > q->max_hw_sectors)) {
1396 printk(KERN_ERR "bio too big device %s (%u > %u)\n",
1397 bdevname(bio->bi_bdev, b),
1403 if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
1406 if (should_fail_request(bio))
1410 * If this device has partitions, remap block n
1411 * of partition p to block n+start(p) of the disk.
1413 blk_partition_remap(bio);
1415 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio))
1418 if (old_sector != -1)
1419 blk_add_trace_remap(q, bio, old_dev, bio->bi_sector,
1422 blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
1424 old_sector = bio->bi_sector;
1425 old_dev = bio->bi_bdev->bd_dev;
1427 if (bio_check_eod(bio, nr_sectors))
1429 if ((bio_empty_barrier(bio) && !q->prepare_flush_fn) ||
1430 (bio_discard(bio) && !q->prepare_discard_fn)) {
1435 ret = q->make_request_fn(q, bio);
1440 * We only want one ->make_request_fn to be active at a time,
1441 * else stack usage with stacked devices could be a problem.
1442 * So use current->bio_{list,tail} to keep a list of requests
1443 * submited by a make_request_fn function.
1444 * current->bio_tail is also used as a flag to say if
1445 * generic_make_request is currently active in this task or not.
1446 * If it is NULL, then no make_request is active. If it is non-NULL,
1447 * then a make_request is active, and new requests should be added
1450 void generic_make_request(struct bio *bio)
1452 if (current->bio_tail) {
1453 /* make_request is active */
1454 *(current->bio_tail) = bio;
1455 bio->bi_next = NULL;
1456 current->bio_tail = &bio->bi_next;
1459 /* following loop may be a bit non-obvious, and so deserves some
1461 * Before entering the loop, bio->bi_next is NULL (as all callers
1462 * ensure that) so we have a list with a single bio.
1463 * We pretend that we have just taken it off a longer list, so
1464 * we assign bio_list to the next (which is NULL) and bio_tail
1465 * to &bio_list, thus initialising the bio_list of new bios to be
1466 * added. __generic_make_request may indeed add some more bios
1467 * through a recursive call to generic_make_request. If it
1468 * did, we find a non-NULL value in bio_list and re-enter the loop
1469 * from the top. In this case we really did just take the bio
1470 * of the top of the list (no pretending) and so fixup bio_list and
1471 * bio_tail or bi_next, and call into __generic_make_request again.
1473 * The loop was structured like this to make only one call to
1474 * __generic_make_request (which is important as it is large and
1475 * inlined) and to keep the structure simple.
1477 BUG_ON(bio->bi_next);
1479 current->bio_list = bio->bi_next;
1480 if (bio->bi_next == NULL)
1481 current->bio_tail = ¤t->bio_list;
1483 bio->bi_next = NULL;
1484 __generic_make_request(bio);
1485 bio = current->bio_list;
1487 current->bio_tail = NULL; /* deactivate */
1489 EXPORT_SYMBOL(generic_make_request);
1492 * submit_bio - submit a bio to the block device layer for I/O
1493 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
1494 * @bio: The &struct bio which describes the I/O
1496 * submit_bio() is very similar in purpose to generic_make_request(), and
1497 * uses that function to do most of the work. Both are fairly rough
1498 * interfaces; @bio must be presetup and ready for I/O.
1501 void submit_bio(int rw, struct bio *bio)
1503 int count = bio_sectors(bio);
1508 * If it's a regular read/write or a barrier with data attached,
1509 * go through the normal accounting stuff before submission.
1511 if (bio_has_data(bio)) {
1513 count_vm_events(PGPGOUT, count);
1515 task_io_account_read(bio->bi_size);
1516 count_vm_events(PGPGIN, count);
1519 if (unlikely(block_dump)) {
1520 char b[BDEVNAME_SIZE];
1521 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
1522 current->comm, task_pid_nr(current),
1523 (rw & WRITE) ? "WRITE" : "READ",
1524 (unsigned long long)bio->bi_sector,
1525 bdevname(bio->bi_bdev, b));
1529 generic_make_request(bio);
1531 EXPORT_SYMBOL(submit_bio);
1534 * blk_rq_check_limits - Helper function to check a request for the queue limit
1536 * @rq: the request being checked
1539 * @rq may have been made based on weaker limitations of upper-level queues
1540 * in request stacking drivers, and it may violate the limitation of @q.
1541 * Since the block layer and the underlying device driver trust @rq
1542 * after it is inserted to @q, it should be checked against @q before
1543 * the insertion using this generic function.
1545 * This function should also be useful for request stacking drivers
1546 * in some cases below, so export this fuction.
1547 * Request stacking drivers like request-based dm may change the queue
1548 * limits while requests are in the queue (e.g. dm's table swapping).
1549 * Such request stacking drivers should check those requests agaist
1550 * the new queue limits again when they dispatch those requests,
1551 * although such checkings are also done against the old queue limits
1552 * when submitting requests.
1554 int blk_rq_check_limits(struct request_queue *q, struct request *rq)
1556 if (rq->nr_sectors > q->max_sectors ||
1557 rq->data_len > q->max_hw_sectors << 9) {
1558 printk(KERN_ERR "%s: over max size limit.\n", __func__);
1563 * queue's settings related to segment counting like q->bounce_pfn
1564 * may differ from that of other stacking queues.
1565 * Recalculate it to check the request correctly on this queue's
1568 blk_recalc_rq_segments(rq);
1569 if (rq->nr_phys_segments > q->max_phys_segments ||
1570 rq->nr_phys_segments > q->max_hw_segments) {
1571 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
1577 EXPORT_SYMBOL_GPL(blk_rq_check_limits);
1580 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1581 * @q: the queue to submit the request
1582 * @rq: the request being queued
1584 int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
1586 unsigned long flags;
1588 if (blk_rq_check_limits(q, rq))
1591 #ifdef CONFIG_FAIL_MAKE_REQUEST
1592 if (rq->rq_disk && rq->rq_disk->part0.make_it_fail &&
1593 should_fail(&fail_make_request, blk_rq_bytes(rq)))
1597 spin_lock_irqsave(q->queue_lock, flags);
1600 * Submitting request must be dequeued before calling this function
1601 * because it will be linked to another request_queue
1603 BUG_ON(blk_queued_rq(rq));
1605 drive_stat_acct(rq, 1);
1606 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
1608 spin_unlock_irqrestore(q->queue_lock, flags);
1612 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
1615 * __end_that_request_first - end I/O on a request
1616 * @req: the request being processed
1617 * @error: %0 for success, < %0 for error
1618 * @nr_bytes: number of bytes to complete
1621 * Ends I/O on a number of bytes attached to @req, and sets it up
1622 * for the next range of segments (if any) in the cluster.
1625 * %0 - we are done with this request, call end_that_request_last()
1626 * %1 - still buffers pending for this request
1628 static int __end_that_request_first(struct request *req, int error,
1631 int total_bytes, bio_nbytes, next_idx = 0;
1634 blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE);
1637 * for a REQ_TYPE_BLOCK_PC request, we want to carry any eventual
1638 * sense key with us all the way through
1640 if (!blk_pc_request(req))
1643 if (error && (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET))) {
1644 printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n",
1645 req->rq_disk ? req->rq_disk->disk_name : "?",
1646 (unsigned long long)req->sector);
1649 if (blk_fs_request(req) && req->rq_disk) {
1650 const int rw = rq_data_dir(req);
1651 struct hd_struct *part;
1654 cpu = part_stat_lock();
1655 part = disk_map_sector_rcu(req->rq_disk, req->sector);
1656 part_stat_add(cpu, part, sectors[rw], nr_bytes >> 9);
1660 total_bytes = bio_nbytes = 0;
1661 while ((bio = req->bio) != NULL) {
1665 * For an empty barrier request, the low level driver must
1666 * store a potential error location in ->sector. We pass
1667 * that back up in ->bi_sector.
1669 if (blk_empty_barrier(req))
1670 bio->bi_sector = req->sector;
1672 if (nr_bytes >= bio->bi_size) {
1673 req->bio = bio->bi_next;
1674 nbytes = bio->bi_size;
1675 req_bio_endio(req, bio, nbytes, error);
1679 int idx = bio->bi_idx + next_idx;
1681 if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
1682 blk_dump_rq_flags(req, "__end_that");
1683 printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n",
1684 __func__, bio->bi_idx, bio->bi_vcnt);
1688 nbytes = bio_iovec_idx(bio, idx)->bv_len;
1689 BIO_BUG_ON(nbytes > bio->bi_size);
1692 * not a complete bvec done
1694 if (unlikely(nbytes > nr_bytes)) {
1695 bio_nbytes += nr_bytes;
1696 total_bytes += nr_bytes;
1701 * advance to the next vector
1704 bio_nbytes += nbytes;
1707 total_bytes += nbytes;
1713 * end more in this run, or just return 'not-done'
1715 if (unlikely(nr_bytes <= 0))
1727 * if the request wasn't completed, update state
1730 req_bio_endio(req, bio, bio_nbytes, error);
1731 bio->bi_idx += next_idx;
1732 bio_iovec(bio)->bv_offset += nr_bytes;
1733 bio_iovec(bio)->bv_len -= nr_bytes;
1736 blk_recalc_rq_sectors(req, total_bytes >> 9);
1737 blk_recalc_rq_segments(req);
1742 * queue lock must be held
1744 static void end_that_request_last(struct request *req, int error)
1746 struct gendisk *disk = req->rq_disk;
1748 blk_delete_timer(req);
1750 if (blk_rq_tagged(req))
1751 blk_queue_end_tag(req->q, req);
1753 if (blk_queued_rq(req))
1754 blkdev_dequeue_request(req);
1756 if (unlikely(laptop_mode) && blk_fs_request(req))
1757 laptop_io_completion();
1760 * Account IO completion. bar_rq isn't accounted as a normal
1761 * IO on queueing nor completion. Accounting the containing
1762 * request is enough.
1764 if (disk && blk_fs_request(req) && req != &req->q->bar_rq) {
1765 unsigned long duration = jiffies - req->start_time;
1766 const int rw = rq_data_dir(req);
1767 struct hd_struct *part;
1770 cpu = part_stat_lock();
1771 part = disk_map_sector_rcu(disk, req->sector);
1773 part_stat_inc(cpu, part, ios[rw]);
1774 part_stat_add(cpu, part, ticks[rw], duration);
1775 part_round_stats(cpu, part);
1776 part_dec_in_flight(part);
1782 req->end_io(req, error);
1784 if (blk_bidi_rq(req))
1785 __blk_put_request(req->next_rq->q, req->next_rq);
1787 __blk_put_request(req->q, req);
1791 static inline void __end_request(struct request *rq, int uptodate,
1792 unsigned int nr_bytes)
1797 error = uptodate ? uptodate : -EIO;
1799 __blk_end_request(rq, error, nr_bytes);
1803 * blk_rq_bytes - Returns bytes left to complete in the entire request
1804 * @rq: the request being processed
1806 unsigned int blk_rq_bytes(struct request *rq)
1808 if (blk_fs_request(rq))
1809 return rq->hard_nr_sectors << 9;
1811 return rq->data_len;
1813 EXPORT_SYMBOL_GPL(blk_rq_bytes);
1816 * blk_rq_cur_bytes - Returns bytes left to complete in the current segment
1817 * @rq: the request being processed
1819 unsigned int blk_rq_cur_bytes(struct request *rq)
1821 if (blk_fs_request(rq))
1822 return rq->current_nr_sectors << 9;
1825 return rq->bio->bi_size;
1827 return rq->data_len;
1829 EXPORT_SYMBOL_GPL(blk_rq_cur_bytes);
1832 * end_queued_request - end all I/O on a queued request
1833 * @rq: the request being processed
1834 * @uptodate: error value or %0/%1 uptodate flag
1837 * Ends all I/O on a request, and removes it from the block layer queues.
1838 * Not suitable for normal I/O completion, unless the driver still has
1839 * the request attached to the block layer.
1842 void end_queued_request(struct request *rq, int uptodate)
1844 __end_request(rq, uptodate, blk_rq_bytes(rq));
1846 EXPORT_SYMBOL(end_queued_request);
1849 * end_dequeued_request - end all I/O on a dequeued request
1850 * @rq: the request being processed
1851 * @uptodate: error value or %0/%1 uptodate flag
1854 * Ends all I/O on a request. The request must already have been
1855 * dequeued using blkdev_dequeue_request(), as is normally the case
1859 void end_dequeued_request(struct request *rq, int uptodate)
1861 __end_request(rq, uptodate, blk_rq_bytes(rq));
1863 EXPORT_SYMBOL(end_dequeued_request);
1867 * end_request - end I/O on the current segment of the request
1868 * @req: the request being processed
1869 * @uptodate: error value or %0/%1 uptodate flag
1872 * Ends I/O on the current segment of a request. If that is the only
1873 * remaining segment, the request is also completed and freed.
1875 * This is a remnant of how older block drivers handled I/O completions.
1876 * Modern drivers typically end I/O on the full request in one go, unless
1877 * they have a residual value to account for. For that case this function
1878 * isn't really useful, unless the residual just happens to be the
1879 * full current segment. In other words, don't use this function in new
1880 * code. Use blk_end_request() or __blk_end_request() to end partial parts
1881 * of a request, or end_dequeued_request() and end_queued_request() to
1882 * completely end IO on a dequeued/queued request.
1885 void end_request(struct request *req, int uptodate)
1887 __end_request(req, uptodate, req->hard_cur_sectors << 9);
1889 EXPORT_SYMBOL(end_request);
1891 static int end_that_request_data(struct request *rq, int error,
1892 unsigned int nr_bytes, unsigned int bidi_bytes)
1895 if (__end_that_request_first(rq, error, nr_bytes))
1898 /* Bidi request must be completed as a whole */
1899 if (blk_bidi_rq(rq) &&
1900 __end_that_request_first(rq->next_rq, error, bidi_bytes))
1908 * blk_end_io - Generic end_io function to complete a request.
1909 * @rq: the request being processed
1910 * @error: %0 for success, < %0 for error
1911 * @nr_bytes: number of bytes to complete @rq
1912 * @bidi_bytes: number of bytes to complete @rq->next_rq
1913 * @drv_callback: function called between completion of bios in the request
1914 * and completion of the request.
1915 * If the callback returns non %0, this helper returns without
1916 * completion of the request.
1919 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
1920 * If @rq has leftover, sets it up for the next range of segments.
1923 * %0 - we are done with this request
1924 * %1 - this request is not freed yet, it still has pending buffers.
1926 static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes,
1927 unsigned int bidi_bytes,
1928 int (drv_callback)(struct request *))
1930 struct request_queue *q = rq->q;
1931 unsigned long flags = 0UL;
1933 if (end_that_request_data(rq, error, nr_bytes, bidi_bytes))
1936 /* Special feature for tricky drivers */
1937 if (drv_callback && drv_callback(rq))
1940 add_disk_randomness(rq->rq_disk);
1942 spin_lock_irqsave(q->queue_lock, flags);
1943 end_that_request_last(rq, error);
1944 spin_unlock_irqrestore(q->queue_lock, flags);
1950 * blk_end_request - Helper function for drivers to complete the request.
1951 * @rq: the request being processed
1952 * @error: %0 for success, < %0 for error
1953 * @nr_bytes: number of bytes to complete
1956 * Ends I/O on a number of bytes attached to @rq.
1957 * If @rq has leftover, sets it up for the next range of segments.
1960 * %0 - we are done with this request
1961 * %1 - still buffers pending for this request
1963 int blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
1965 return blk_end_io(rq, error, nr_bytes, 0, NULL);
1967 EXPORT_SYMBOL_GPL(blk_end_request);
1970 * __blk_end_request - Helper function for drivers to complete the request.
1971 * @rq: the request being processed
1972 * @error: %0 for success, < %0 for error
1973 * @nr_bytes: number of bytes to complete
1976 * Must be called with queue lock held unlike blk_end_request().
1979 * %0 - we are done with this request
1980 * %1 - still buffers pending for this request
1982 int __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
1984 if (rq->bio && __end_that_request_first(rq, error, nr_bytes))
1987 add_disk_randomness(rq->rq_disk);
1989 end_that_request_last(rq, error);
1993 EXPORT_SYMBOL_GPL(__blk_end_request);
1996 * blk_end_bidi_request - Helper function for drivers to complete bidi request.
1997 * @rq: the bidi request being processed
1998 * @error: %0 for success, < %0 for error
1999 * @nr_bytes: number of bytes to complete @rq
2000 * @bidi_bytes: number of bytes to complete @rq->next_rq
2003 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2006 * %0 - we are done with this request
2007 * %1 - still buffers pending for this request
2009 int blk_end_bidi_request(struct request *rq, int error, unsigned int nr_bytes,
2010 unsigned int bidi_bytes)
2012 return blk_end_io(rq, error, nr_bytes, bidi_bytes, NULL);
2014 EXPORT_SYMBOL_GPL(blk_end_bidi_request);
2017 * blk_update_request - Special helper function for request stacking drivers
2018 * @rq: the request being processed
2019 * @error: %0 for success, < %0 for error
2020 * @nr_bytes: number of bytes to complete @rq
2023 * Ends I/O on a number of bytes attached to @rq, but doesn't complete
2024 * the request structure even if @rq doesn't have leftover.
2025 * If @rq has leftover, sets it up for the next range of segments.
2027 * This special helper function is only for request stacking drivers
2028 * (e.g. request-based dm) so that they can handle partial completion.
2029 * Actual device drivers should use blk_end_request instead.
2031 void blk_update_request(struct request *rq, int error, unsigned int nr_bytes)
2033 if (!end_that_request_data(rq, error, nr_bytes, 0)) {
2035 * These members are not updated in end_that_request_data()
2036 * when all bios are completed.
2037 * Update them so that the request stacking driver can find
2038 * how many bytes remain in the request later.
2040 rq->nr_sectors = rq->hard_nr_sectors = 0;
2041 rq->current_nr_sectors = rq->hard_cur_sectors = 0;
2044 EXPORT_SYMBOL_GPL(blk_update_request);
2047 * blk_end_request_callback - Special helper function for tricky drivers
2048 * @rq: the request being processed
2049 * @error: %0 for success, < %0 for error
2050 * @nr_bytes: number of bytes to complete
2051 * @drv_callback: function called between completion of bios in the request
2052 * and completion of the request.
2053 * If the callback returns non %0, this helper returns without
2054 * completion of the request.
2057 * Ends I/O on a number of bytes attached to @rq.
2058 * If @rq has leftover, sets it up for the next range of segments.
2060 * This special helper function is used only for existing tricky drivers.
2061 * (e.g. cdrom_newpc_intr() of ide-cd)
2062 * This interface will be removed when such drivers are rewritten.
2063 * Don't use this interface in other places anymore.
2066 * %0 - we are done with this request
2067 * %1 - this request is not freed yet.
2068 * this request still has pending buffers or
2069 * the driver doesn't want to finish this request yet.
2071 int blk_end_request_callback(struct request *rq, int error,
2072 unsigned int nr_bytes,
2073 int (drv_callback)(struct request *))
2075 return blk_end_io(rq, error, nr_bytes, 0, drv_callback);
2077 EXPORT_SYMBOL_GPL(blk_end_request_callback);
2079 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2082 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw, and
2083 we want BIO_RW_AHEAD (bit 1) to imply REQ_FAILFAST (bit 1). */
2084 rq->cmd_flags |= (bio->bi_rw & 3);
2086 if (bio_has_data(bio)) {
2087 rq->nr_phys_segments = bio_phys_segments(q, bio);
2088 rq->buffer = bio_data(bio);
2090 rq->current_nr_sectors = bio_cur_sectors(bio);
2091 rq->hard_cur_sectors = rq->current_nr_sectors;
2092 rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
2093 rq->data_len = bio->bi_size;
2095 rq->bio = rq->biotail = bio;
2098 rq->rq_disk = bio->bi_bdev->bd_disk;
2101 int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
2103 return queue_work(kblockd_workqueue, work);
2105 EXPORT_SYMBOL(kblockd_schedule_work);
2107 void kblockd_flush_work(struct work_struct *work)
2109 cancel_work_sync(work);
2111 EXPORT_SYMBOL(kblockd_flush_work);
2113 int __init blk_dev_init(void)
2115 kblockd_workqueue = create_workqueue("kblockd");
2116 if (!kblockd_workqueue)
2117 panic("Failed to create kblockd\n");
2119 request_cachep = kmem_cache_create("blkdev_requests",
2120 sizeof(struct request), 0, SLAB_PANIC, NULL);
2122 blk_requestq_cachep = kmem_cache_create("blkdev_queue",
2123 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);