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/blk-mq.h>
20 #include <linux/highmem.h>
22 #include <linux/kernel_stat.h>
23 #include <linux/string.h>
24 #include <linux/init.h>
25 #include <linux/completion.h>
26 #include <linux/slab.h>
27 #include <linux/swap.h>
28 #include <linux/writeback.h>
29 #include <linux/task_io_accounting_ops.h>
30 #include <linux/fault-inject.h>
31 #include <linux/list_sort.h>
32 #include <linux/delay.h>
33 #include <linux/ratelimit.h>
34 #include <linux/pm_runtime.h>
35 #include <linux/blk-cgroup.h>
37 #define CREATE_TRACE_POINTS
38 #include <trace/events/block.h>
43 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
44 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
45 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
46 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
47 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
49 DEFINE_IDA(blk_queue_ida);
52 * For the allocated request tables
54 struct kmem_cache *request_cachep = NULL;
57 * For queue allocation
59 struct kmem_cache *blk_requestq_cachep;
62 * Controlling structure to kblockd
64 static struct workqueue_struct *kblockd_workqueue;
66 static void blk_clear_congested(struct request_list *rl, int sync)
68 #ifdef CONFIG_CGROUP_WRITEBACK
69 clear_wb_congested(rl->blkg->wb_congested, sync);
72 * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't
73 * flip its congestion state for events on other blkcgs.
75 if (rl == &rl->q->root_rl)
76 clear_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
80 static void blk_set_congested(struct request_list *rl, int sync)
82 #ifdef CONFIG_CGROUP_WRITEBACK
83 set_wb_congested(rl->blkg->wb_congested, sync);
85 /* see blk_clear_congested() */
86 if (rl == &rl->q->root_rl)
87 set_wb_congested(rl->q->backing_dev_info.wb.congested, sync);
91 void blk_queue_congestion_threshold(struct request_queue *q)
95 nr = q->nr_requests - (q->nr_requests / 8) + 1;
96 if (nr > q->nr_requests)
98 q->nr_congestion_on = nr;
100 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
103 q->nr_congestion_off = nr;
107 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
110 * Locates the passed device's request queue and returns the address of its
111 * backing_dev_info. This function can only be called if @bdev is opened
112 * and the return value is never NULL.
114 struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
116 struct request_queue *q = bdev_get_queue(bdev);
118 return &q->backing_dev_info;
120 EXPORT_SYMBOL(blk_get_backing_dev_info);
122 void blk_rq_init(struct request_queue *q, struct request *rq)
124 memset(rq, 0, sizeof(*rq));
126 INIT_LIST_HEAD(&rq->queuelist);
127 INIT_LIST_HEAD(&rq->timeout_list);
130 rq->__sector = (sector_t) -1;
131 INIT_HLIST_NODE(&rq->hash);
132 RB_CLEAR_NODE(&rq->rb_node);
134 rq->cmd_len = BLK_MAX_CDB;
136 rq->start_time = jiffies;
137 set_start_time_ns(rq);
140 EXPORT_SYMBOL(blk_rq_init);
142 static void req_bio_endio(struct request *rq, struct bio *bio,
143 unsigned int nbytes, int error)
146 bio->bi_error = error;
148 if (unlikely(rq->cmd_flags & REQ_QUIET))
149 bio_set_flag(bio, BIO_QUIET);
151 bio_advance(bio, nbytes);
153 /* don't actually finish bio if it's part of flush sequence */
154 if (bio->bi_iter.bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
158 void blk_dump_rq_flags(struct request *rq, char *msg)
162 printk(KERN_INFO "%s: dev %s: type=%x, flags=%llx\n", msg,
163 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
164 (unsigned long long) rq->cmd_flags);
166 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
167 (unsigned long long)blk_rq_pos(rq),
168 blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
169 printk(KERN_INFO " bio %p, biotail %p, len %u\n",
170 rq->bio, rq->biotail, blk_rq_bytes(rq));
172 if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
173 printk(KERN_INFO " cdb: ");
174 for (bit = 0; bit < BLK_MAX_CDB; bit++)
175 printk("%02x ", rq->cmd[bit]);
179 EXPORT_SYMBOL(blk_dump_rq_flags);
181 static void blk_delay_work(struct work_struct *work)
183 struct request_queue *q;
185 q = container_of(work, struct request_queue, delay_work.work);
186 spin_lock_irq(q->queue_lock);
188 spin_unlock_irq(q->queue_lock);
192 * blk_delay_queue - restart queueing after defined interval
193 * @q: The &struct request_queue in question
194 * @msecs: Delay in msecs
197 * Sometimes queueing needs to be postponed for a little while, to allow
198 * resources to come back. This function will make sure that queueing is
199 * restarted around the specified time. Queue lock must be held.
201 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
203 if (likely(!blk_queue_dead(q)))
204 queue_delayed_work(kblockd_workqueue, &q->delay_work,
205 msecs_to_jiffies(msecs));
207 EXPORT_SYMBOL(blk_delay_queue);
210 * blk_start_queue - restart a previously stopped queue
211 * @q: The &struct request_queue in question
214 * blk_start_queue() will clear the stop flag on the queue, and call
215 * the request_fn for the queue if it was in a stopped state when
216 * entered. Also see blk_stop_queue(). Queue lock must be held.
218 void blk_start_queue(struct request_queue *q)
220 WARN_ON(!irqs_disabled());
222 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
225 EXPORT_SYMBOL(blk_start_queue);
228 * blk_stop_queue - stop a queue
229 * @q: The &struct request_queue in question
232 * The Linux block layer assumes that a block driver will consume all
233 * entries on the request queue when the request_fn strategy is called.
234 * Often this will not happen, because of hardware limitations (queue
235 * depth settings). If a device driver gets a 'queue full' response,
236 * or if it simply chooses not to queue more I/O at one point, it can
237 * call this function to prevent the request_fn from being called until
238 * the driver has signalled it's ready to go again. This happens by calling
239 * blk_start_queue() to restart queue operations. Queue lock must be held.
241 void blk_stop_queue(struct request_queue *q)
243 cancel_delayed_work(&q->delay_work);
244 queue_flag_set(QUEUE_FLAG_STOPPED, q);
246 EXPORT_SYMBOL(blk_stop_queue);
249 * blk_sync_queue - cancel any pending callbacks on a queue
253 * The block layer may perform asynchronous callback activity
254 * on a queue, such as calling the unplug function after a timeout.
255 * A block device may call blk_sync_queue to ensure that any
256 * such activity is cancelled, thus allowing it to release resources
257 * that the callbacks might use. The caller must already have made sure
258 * that its ->make_request_fn will not re-add plugging prior to calling
261 * This function does not cancel any asynchronous activity arising
262 * out of elevator or throttling code. That would require elevator_exit()
263 * and blkcg_exit_queue() to be called with queue lock initialized.
266 void blk_sync_queue(struct request_queue *q)
268 del_timer_sync(&q->timeout);
271 struct blk_mq_hw_ctx *hctx;
274 queue_for_each_hw_ctx(q, hctx, i) {
275 cancel_delayed_work_sync(&hctx->run_work);
276 cancel_delayed_work_sync(&hctx->delay_work);
279 cancel_delayed_work_sync(&q->delay_work);
282 EXPORT_SYMBOL(blk_sync_queue);
285 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
286 * @q: The queue to run
289 * Invoke request handling on a queue if there are any pending requests.
290 * May be used to restart request handling after a request has completed.
291 * This variant runs the queue whether or not the queue has been
292 * stopped. Must be called with the queue lock held and interrupts
293 * disabled. See also @blk_run_queue.
295 inline void __blk_run_queue_uncond(struct request_queue *q)
297 if (unlikely(blk_queue_dead(q)))
301 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
302 * the queue lock internally. As a result multiple threads may be
303 * running such a request function concurrently. Keep track of the
304 * number of active request_fn invocations such that blk_drain_queue()
305 * can wait until all these request_fn calls have finished.
307 q->request_fn_active++;
309 q->request_fn_active--;
311 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond);
314 * __blk_run_queue - run a single device queue
315 * @q: The queue to run
318 * See @blk_run_queue. This variant must be called with the queue lock
319 * held and interrupts disabled.
321 void __blk_run_queue(struct request_queue *q)
323 if (unlikely(blk_queue_stopped(q)))
326 __blk_run_queue_uncond(q);
328 EXPORT_SYMBOL(__blk_run_queue);
331 * blk_run_queue_async - run a single device queue in workqueue context
332 * @q: The queue to run
335 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
336 * of us. The caller must hold the queue lock.
338 void blk_run_queue_async(struct request_queue *q)
340 if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
341 mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
343 EXPORT_SYMBOL(blk_run_queue_async);
346 * blk_run_queue - run a single device queue
347 * @q: The queue to run
350 * Invoke request handling on this queue, if it has pending work to do.
351 * May be used to restart queueing when a request has completed.
353 void blk_run_queue(struct request_queue *q)
357 spin_lock_irqsave(q->queue_lock, flags);
359 spin_unlock_irqrestore(q->queue_lock, flags);
361 EXPORT_SYMBOL(blk_run_queue);
363 void blk_put_queue(struct request_queue *q)
365 kobject_put(&q->kobj);
367 EXPORT_SYMBOL(blk_put_queue);
370 * __blk_drain_queue - drain requests from request_queue
372 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
374 * Drain requests from @q. If @drain_all is set, all requests are drained.
375 * If not, only ELVPRIV requests are drained. The caller is responsible
376 * for ensuring that no new requests which need to be drained are queued.
378 static void __blk_drain_queue(struct request_queue *q, bool drain_all)
379 __releases(q->queue_lock)
380 __acquires(q->queue_lock)
384 lockdep_assert_held(q->queue_lock);
390 * The caller might be trying to drain @q before its
391 * elevator is initialized.
394 elv_drain_elevator(q);
396 blkcg_drain_queue(q);
399 * This function might be called on a queue which failed
400 * driver init after queue creation or is not yet fully
401 * active yet. Some drivers (e.g. fd and loop) get unhappy
402 * in such cases. Kick queue iff dispatch queue has
403 * something on it and @q has request_fn set.
405 if (!list_empty(&q->queue_head) && q->request_fn)
408 drain |= q->nr_rqs_elvpriv;
409 drain |= q->request_fn_active;
412 * Unfortunately, requests are queued at and tracked from
413 * multiple places and there's no single counter which can
414 * be drained. Check all the queues and counters.
417 struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
418 drain |= !list_empty(&q->queue_head);
419 for (i = 0; i < 2; i++) {
420 drain |= q->nr_rqs[i];
421 drain |= q->in_flight[i];
423 drain |= !list_empty(&fq->flush_queue[i]);
430 spin_unlock_irq(q->queue_lock);
434 spin_lock_irq(q->queue_lock);
438 * With queue marked dead, any woken up waiter will fail the
439 * allocation path, so the wakeup chaining is lost and we're
440 * left with hung waiters. We need to wake up those waiters.
443 struct request_list *rl;
445 blk_queue_for_each_rl(rl, q)
446 for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
447 wake_up_all(&rl->wait[i]);
452 * blk_queue_bypass_start - enter queue bypass mode
453 * @q: queue of interest
455 * In bypass mode, only the dispatch FIFO queue of @q is used. This
456 * function makes @q enter bypass mode and drains all requests which were
457 * throttled or issued before. On return, it's guaranteed that no request
458 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
459 * inside queue or RCU read lock.
461 void blk_queue_bypass_start(struct request_queue *q)
463 spin_lock_irq(q->queue_lock);
465 queue_flag_set(QUEUE_FLAG_BYPASS, q);
466 spin_unlock_irq(q->queue_lock);
469 * Queues start drained. Skip actual draining till init is
470 * complete. This avoids lenghty delays during queue init which
471 * can happen many times during boot.
473 if (blk_queue_init_done(q)) {
474 spin_lock_irq(q->queue_lock);
475 __blk_drain_queue(q, false);
476 spin_unlock_irq(q->queue_lock);
478 /* ensure blk_queue_bypass() is %true inside RCU read lock */
482 EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
485 * blk_queue_bypass_end - leave queue bypass mode
486 * @q: queue of interest
488 * Leave bypass mode and restore the normal queueing behavior.
490 void blk_queue_bypass_end(struct request_queue *q)
492 spin_lock_irq(q->queue_lock);
493 if (!--q->bypass_depth)
494 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
495 WARN_ON_ONCE(q->bypass_depth < 0);
496 spin_unlock_irq(q->queue_lock);
498 EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
500 void blk_set_queue_dying(struct request_queue *q)
502 queue_flag_set_unlocked(QUEUE_FLAG_DYING, q);
505 blk_mq_wake_waiters(q);
507 struct request_list *rl;
509 blk_queue_for_each_rl(rl, q) {
511 wake_up(&rl->wait[BLK_RW_SYNC]);
512 wake_up(&rl->wait[BLK_RW_ASYNC]);
517 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
520 * blk_cleanup_queue - shutdown a request queue
521 * @q: request queue to shutdown
523 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
524 * put it. All future requests will be failed immediately with -ENODEV.
526 void blk_cleanup_queue(struct request_queue *q)
528 spinlock_t *lock = q->queue_lock;
530 /* mark @q DYING, no new request or merges will be allowed afterwards */
531 mutex_lock(&q->sysfs_lock);
532 blk_set_queue_dying(q);
536 * A dying queue is permanently in bypass mode till released. Note
537 * that, unlike blk_queue_bypass_start(), we aren't performing
538 * synchronize_rcu() after entering bypass mode to avoid the delay
539 * as some drivers create and destroy a lot of queues while
540 * probing. This is still safe because blk_release_queue() will be
541 * called only after the queue refcnt drops to zero and nothing,
542 * RCU or not, would be traversing the queue by then.
545 queue_flag_set(QUEUE_FLAG_BYPASS, q);
547 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
548 queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
549 queue_flag_set(QUEUE_FLAG_DYING, q);
550 spin_unlock_irq(lock);
551 mutex_unlock(&q->sysfs_lock);
554 * Drain all requests queued before DYING marking. Set DEAD flag to
555 * prevent that q->request_fn() gets invoked after draining finished.
558 blk_mq_freeze_queue(q);
562 __blk_drain_queue(q, true);
564 queue_flag_set(QUEUE_FLAG_DEAD, q);
565 spin_unlock_irq(lock);
567 /* @q won't process any more request, flush async actions */
568 del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
572 blk_mq_free_queue(q);
575 if (q->queue_lock != &q->__queue_lock)
576 q->queue_lock = &q->__queue_lock;
577 spin_unlock_irq(lock);
579 bdi_destroy(&q->backing_dev_info);
581 /* @q is and will stay empty, shutdown and put */
584 EXPORT_SYMBOL(blk_cleanup_queue);
586 /* Allocate memory local to the request queue */
587 static void *alloc_request_struct(gfp_t gfp_mask, void *data)
589 int nid = (int)(long)data;
590 return kmem_cache_alloc_node(request_cachep, gfp_mask, nid);
593 static void free_request_struct(void *element, void *unused)
595 kmem_cache_free(request_cachep, element);
598 int blk_init_rl(struct request_list *rl, struct request_queue *q,
601 if (unlikely(rl->rq_pool))
605 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
606 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
607 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
608 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
610 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, alloc_request_struct,
612 (void *)(long)q->node, gfp_mask,
620 void blk_exit_rl(struct request_list *rl)
623 mempool_destroy(rl->rq_pool);
626 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
628 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
630 EXPORT_SYMBOL(blk_alloc_queue);
632 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
634 struct request_queue *q;
637 q = kmem_cache_alloc_node(blk_requestq_cachep,
638 gfp_mask | __GFP_ZERO, node_id);
642 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
646 q->bio_split = bioset_create(BIO_POOL_SIZE, 0);
650 q->backing_dev_info.ra_pages =
651 (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
652 q->backing_dev_info.capabilities = BDI_CAP_CGROUP_WRITEBACK;
653 q->backing_dev_info.name = "block";
656 err = bdi_init(&q->backing_dev_info);
660 setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
661 laptop_mode_timer_fn, (unsigned long) q);
662 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
663 INIT_LIST_HEAD(&q->queue_head);
664 INIT_LIST_HEAD(&q->timeout_list);
665 INIT_LIST_HEAD(&q->icq_list);
666 #ifdef CONFIG_BLK_CGROUP
667 INIT_LIST_HEAD(&q->blkg_list);
669 INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
671 kobject_init(&q->kobj, &blk_queue_ktype);
673 mutex_init(&q->sysfs_lock);
674 spin_lock_init(&q->__queue_lock);
677 * By default initialize queue_lock to internal lock and driver can
678 * override it later if need be.
680 q->queue_lock = &q->__queue_lock;
683 * A queue starts its life with bypass turned on to avoid
684 * unnecessary bypass on/off overhead and nasty surprises during
685 * init. The initial bypass will be finished when the queue is
686 * registered by blk_register_queue().
689 __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
691 init_waitqueue_head(&q->mq_freeze_wq);
693 if (blkcg_init_queue(q))
699 bdi_destroy(&q->backing_dev_info);
701 bioset_free(q->bio_split);
703 ida_simple_remove(&blk_queue_ida, q->id);
705 kmem_cache_free(blk_requestq_cachep, q);
708 EXPORT_SYMBOL(blk_alloc_queue_node);
711 * blk_init_queue - prepare a request queue for use with a block device
712 * @rfn: The function to be called to process requests that have been
713 * placed on the queue.
714 * @lock: Request queue spin lock
717 * If a block device wishes to use the standard request handling procedures,
718 * which sorts requests and coalesces adjacent requests, then it must
719 * call blk_init_queue(). The function @rfn will be called when there
720 * are requests on the queue that need to be processed. If the device
721 * supports plugging, then @rfn may not be called immediately when requests
722 * are available on the queue, but may be called at some time later instead.
723 * Plugged queues are generally unplugged when a buffer belonging to one
724 * of the requests on the queue is needed, or due to memory pressure.
726 * @rfn is not required, or even expected, to remove all requests off the
727 * queue, but only as many as it can handle at a time. If it does leave
728 * requests on the queue, it is responsible for arranging that the requests
729 * get dealt with eventually.
731 * The queue spin lock must be held while manipulating the requests on the
732 * request queue; this lock will be taken also from interrupt context, so irq
733 * disabling is needed for it.
735 * Function returns a pointer to the initialized request queue, or %NULL if
739 * blk_init_queue() must be paired with a blk_cleanup_queue() call
740 * when the block device is deactivated (such as at module unload).
743 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
745 return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
747 EXPORT_SYMBOL(blk_init_queue);
749 struct request_queue *
750 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
752 struct request_queue *uninit_q, *q;
754 uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
758 q = blk_init_allocated_queue(uninit_q, rfn, lock);
760 blk_cleanup_queue(uninit_q);
764 EXPORT_SYMBOL(blk_init_queue_node);
766 static void blk_queue_bio(struct request_queue *q, struct bio *bio);
768 struct request_queue *
769 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
775 q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, 0);
779 if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
783 q->prep_rq_fn = NULL;
784 q->unprep_rq_fn = NULL;
785 q->queue_flags |= QUEUE_FLAG_DEFAULT;
787 /* Override internal queue lock with supplied lock pointer */
789 q->queue_lock = lock;
792 * This also sets hw/phys segments, boundary and size
794 blk_queue_make_request(q, blk_queue_bio);
796 q->sg_reserved_size = INT_MAX;
798 /* Protect q->elevator from elevator_change */
799 mutex_lock(&q->sysfs_lock);
802 if (elevator_init(q, NULL)) {
803 mutex_unlock(&q->sysfs_lock);
807 mutex_unlock(&q->sysfs_lock);
812 blk_free_flush_queue(q->fq);
815 EXPORT_SYMBOL(blk_init_allocated_queue);
817 bool blk_get_queue(struct request_queue *q)
819 if (likely(!blk_queue_dying(q))) {
826 EXPORT_SYMBOL(blk_get_queue);
828 static inline void blk_free_request(struct request_list *rl, struct request *rq)
830 if (rq->cmd_flags & REQ_ELVPRIV) {
831 elv_put_request(rl->q, rq);
833 put_io_context(rq->elv.icq->ioc);
836 mempool_free(rq, rl->rq_pool);
840 * ioc_batching returns true if the ioc is a valid batching request and
841 * should be given priority access to a request.
843 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
849 * Make sure the process is able to allocate at least 1 request
850 * even if the batch times out, otherwise we could theoretically
853 return ioc->nr_batch_requests == q->nr_batching ||
854 (ioc->nr_batch_requests > 0
855 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
859 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
860 * will cause the process to be a "batcher" on all queues in the system. This
861 * is the behaviour we want though - once it gets a wakeup it should be given
864 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
866 if (!ioc || ioc_batching(q, ioc))
869 ioc->nr_batch_requests = q->nr_batching;
870 ioc->last_waited = jiffies;
873 static void __freed_request(struct request_list *rl, int sync)
875 struct request_queue *q = rl->q;
877 if (rl->count[sync] < queue_congestion_off_threshold(q))
878 blk_clear_congested(rl, sync);
880 if (rl->count[sync] + 1 <= q->nr_requests) {
881 if (waitqueue_active(&rl->wait[sync]))
882 wake_up(&rl->wait[sync]);
884 blk_clear_rl_full(rl, sync);
889 * A request has just been released. Account for it, update the full and
890 * congestion status, wake up any waiters. Called under q->queue_lock.
892 static void freed_request(struct request_list *rl, unsigned int flags)
894 struct request_queue *q = rl->q;
895 int sync = rw_is_sync(flags);
899 if (flags & REQ_ELVPRIV)
902 __freed_request(rl, sync);
904 if (unlikely(rl->starved[sync ^ 1]))
905 __freed_request(rl, sync ^ 1);
908 int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
910 struct request_list *rl;
911 int on_thresh, off_thresh;
913 spin_lock_irq(q->queue_lock);
915 blk_queue_congestion_threshold(q);
916 on_thresh = queue_congestion_on_threshold(q);
917 off_thresh = queue_congestion_off_threshold(q);
919 blk_queue_for_each_rl(rl, q) {
920 if (rl->count[BLK_RW_SYNC] >= on_thresh)
921 blk_set_congested(rl, BLK_RW_SYNC);
922 else if (rl->count[BLK_RW_SYNC] < off_thresh)
923 blk_clear_congested(rl, BLK_RW_SYNC);
925 if (rl->count[BLK_RW_ASYNC] >= on_thresh)
926 blk_set_congested(rl, BLK_RW_ASYNC);
927 else if (rl->count[BLK_RW_ASYNC] < off_thresh)
928 blk_clear_congested(rl, BLK_RW_ASYNC);
930 if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
931 blk_set_rl_full(rl, BLK_RW_SYNC);
933 blk_clear_rl_full(rl, BLK_RW_SYNC);
934 wake_up(&rl->wait[BLK_RW_SYNC]);
937 if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
938 blk_set_rl_full(rl, BLK_RW_ASYNC);
940 blk_clear_rl_full(rl, BLK_RW_ASYNC);
941 wake_up(&rl->wait[BLK_RW_ASYNC]);
945 spin_unlock_irq(q->queue_lock);
950 * Determine if elevator data should be initialized when allocating the
951 * request associated with @bio.
953 static bool blk_rq_should_init_elevator(struct bio *bio)
959 * Flush requests do not use the elevator so skip initialization.
960 * This allows a request to share the flush and elevator data.
962 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
969 * rq_ioc - determine io_context for request allocation
970 * @bio: request being allocated is for this bio (can be %NULL)
972 * Determine io_context to use for request allocation for @bio. May return
973 * %NULL if %current->io_context doesn't exist.
975 static struct io_context *rq_ioc(struct bio *bio)
977 #ifdef CONFIG_BLK_CGROUP
978 if (bio && bio->bi_ioc)
981 return current->io_context;
985 * __get_request - get a free request
986 * @rl: request list to allocate from
987 * @rw_flags: RW and SYNC flags
988 * @bio: bio to allocate request for (can be %NULL)
989 * @gfp_mask: allocation mask
991 * Get a free request from @q. This function may fail under memory
992 * pressure or if @q is dead.
994 * Must be called with @q->queue_lock held and,
995 * Returns ERR_PTR on failure, with @q->queue_lock held.
996 * Returns request pointer on success, with @q->queue_lock *not held*.
998 static struct request *__get_request(struct request_list *rl, int rw_flags,
999 struct bio *bio, gfp_t gfp_mask)
1001 struct request_queue *q = rl->q;
1003 struct elevator_type *et = q->elevator->type;
1004 struct io_context *ioc = rq_ioc(bio);
1005 struct io_cq *icq = NULL;
1006 const bool is_sync = rw_is_sync(rw_flags) != 0;
1009 if (unlikely(blk_queue_dying(q)))
1010 return ERR_PTR(-ENODEV);
1012 may_queue = elv_may_queue(q, rw_flags);
1013 if (may_queue == ELV_MQUEUE_NO)
1016 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
1017 if (rl->count[is_sync]+1 >= q->nr_requests) {
1019 * The queue will fill after this allocation, so set
1020 * it as full, and mark this process as "batching".
1021 * This process will be allowed to complete a batch of
1022 * requests, others will be blocked.
1024 if (!blk_rl_full(rl, is_sync)) {
1025 ioc_set_batching(q, ioc);
1026 blk_set_rl_full(rl, is_sync);
1028 if (may_queue != ELV_MQUEUE_MUST
1029 && !ioc_batching(q, ioc)) {
1031 * The queue is full and the allocating
1032 * process is not a "batcher", and not
1033 * exempted by the IO scheduler
1035 return ERR_PTR(-ENOMEM);
1039 blk_set_congested(rl, is_sync);
1043 * Only allow batching queuers to allocate up to 50% over the defined
1044 * limit of requests, otherwise we could have thousands of requests
1045 * allocated with any setting of ->nr_requests
1047 if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
1048 return ERR_PTR(-ENOMEM);
1050 q->nr_rqs[is_sync]++;
1051 rl->count[is_sync]++;
1052 rl->starved[is_sync] = 0;
1055 * Decide whether the new request will be managed by elevator. If
1056 * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
1057 * prevent the current elevator from being destroyed until the new
1058 * request is freed. This guarantees icq's won't be destroyed and
1059 * makes creating new ones safe.
1061 * Also, lookup icq while holding queue_lock. If it doesn't exist,
1062 * it will be created after releasing queue_lock.
1064 if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
1065 rw_flags |= REQ_ELVPRIV;
1066 q->nr_rqs_elvpriv++;
1067 if (et->icq_cache && ioc)
1068 icq = ioc_lookup_icq(ioc, q);
1071 if (blk_queue_io_stat(q))
1072 rw_flags |= REQ_IO_STAT;
1073 spin_unlock_irq(q->queue_lock);
1075 /* allocate and init request */
1076 rq = mempool_alloc(rl->rq_pool, gfp_mask);
1081 blk_rq_set_rl(rq, rl);
1082 rq->cmd_flags = rw_flags | REQ_ALLOCED;
1085 if (rw_flags & REQ_ELVPRIV) {
1086 if (unlikely(et->icq_cache && !icq)) {
1088 icq = ioc_create_icq(ioc, q, gfp_mask);
1094 if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
1097 /* @rq->elv.icq holds io_context until @rq is freed */
1099 get_io_context(icq->ioc);
1103 * ioc may be NULL here, and ioc_batching will be false. That's
1104 * OK, if the queue is under the request limit then requests need
1105 * not count toward the nr_batch_requests limit. There will always
1106 * be some limit enforced by BLK_BATCH_TIME.
1108 if (ioc_batching(q, ioc))
1109 ioc->nr_batch_requests--;
1111 trace_block_getrq(q, bio, rw_flags & 1);
1116 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1117 * and may fail indefinitely under memory pressure and thus
1118 * shouldn't stall IO. Treat this request as !elvpriv. This will
1119 * disturb iosched and blkcg but weird is bettern than dead.
1121 printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1122 __func__, dev_name(q->backing_dev_info.dev));
1124 rq->cmd_flags &= ~REQ_ELVPRIV;
1127 spin_lock_irq(q->queue_lock);
1128 q->nr_rqs_elvpriv--;
1129 spin_unlock_irq(q->queue_lock);
1134 * Allocation failed presumably due to memory. Undo anything we
1135 * might have messed up.
1137 * Allocating task should really be put onto the front of the wait
1138 * queue, but this is pretty rare.
1140 spin_lock_irq(q->queue_lock);
1141 freed_request(rl, rw_flags);
1144 * in the very unlikely event that allocation failed and no
1145 * requests for this direction was pending, mark us starved so that
1146 * freeing of a request in the other direction will notice
1147 * us. another possible fix would be to split the rq mempool into
1151 if (unlikely(rl->count[is_sync] == 0))
1152 rl->starved[is_sync] = 1;
1153 return ERR_PTR(-ENOMEM);
1157 * get_request - get a free request
1158 * @q: request_queue to allocate request from
1159 * @rw_flags: RW and SYNC flags
1160 * @bio: bio to allocate request for (can be %NULL)
1161 * @gfp_mask: allocation mask
1163 * Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this
1164 * function keeps retrying under memory pressure and fails iff @q is dead.
1166 * Must be called with @q->queue_lock held and,
1167 * Returns ERR_PTR on failure, with @q->queue_lock held.
1168 * Returns request pointer on success, with @q->queue_lock *not held*.
1170 static struct request *get_request(struct request_queue *q, int rw_flags,
1171 struct bio *bio, gfp_t gfp_mask)
1173 const bool is_sync = rw_is_sync(rw_flags) != 0;
1175 struct request_list *rl;
1178 rl = blk_get_rl(q, bio); /* transferred to @rq on success */
1180 rq = __get_request(rl, rw_flags, bio, gfp_mask);
1184 if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) {
1189 /* wait on @rl and retry */
1190 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
1191 TASK_UNINTERRUPTIBLE);
1193 trace_block_sleeprq(q, bio, rw_flags & 1);
1195 spin_unlock_irq(q->queue_lock);
1199 * After sleeping, we become a "batching" process and will be able
1200 * to allocate at least one request, and up to a big batch of them
1201 * for a small period time. See ioc_batching, ioc_set_batching
1203 ioc_set_batching(q, current->io_context);
1205 spin_lock_irq(q->queue_lock);
1206 finish_wait(&rl->wait[is_sync], &wait);
1211 static struct request *blk_old_get_request(struct request_queue *q, int rw,
1216 BUG_ON(rw != READ && rw != WRITE);
1218 /* create ioc upfront */
1219 create_io_context(gfp_mask, q->node);
1221 spin_lock_irq(q->queue_lock);
1222 rq = get_request(q, rw, NULL, gfp_mask);
1224 spin_unlock_irq(q->queue_lock);
1225 /* q->queue_lock is unlocked at this point */
1230 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
1233 return blk_mq_alloc_request(q, rw, gfp_mask, false);
1235 return blk_old_get_request(q, rw, gfp_mask);
1237 EXPORT_SYMBOL(blk_get_request);
1240 * blk_make_request - given a bio, allocate a corresponding struct request.
1241 * @q: target request queue
1242 * @bio: The bio describing the memory mappings that will be submitted for IO.
1243 * It may be a chained-bio properly constructed by block/bio layer.
1244 * @gfp_mask: gfp flags to be used for memory allocation
1246 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1247 * type commands. Where the struct request needs to be farther initialized by
1248 * the caller. It is passed a &struct bio, which describes the memory info of
1251 * The caller of blk_make_request must make sure that bi_io_vec
1252 * are set to describe the memory buffers. That bio_data_dir() will return
1253 * the needed direction of the request. (And all bio's in the passed bio-chain
1254 * are properly set accordingly)
1256 * If called under none-sleepable conditions, mapped bio buffers must not
1257 * need bouncing, by calling the appropriate masked or flagged allocator,
1258 * suitable for the target device. Otherwise the call to blk_queue_bounce will
1261 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1262 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
1263 * anything but the first bio in the chain. Otherwise you risk waiting for IO
1264 * completion of a bio that hasn't been submitted yet, thus resulting in a
1265 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
1266 * of bio_alloc(), as that avoids the mempool deadlock.
1267 * If possible a big IO should be split into smaller parts when allocation
1268 * fails. Partial allocation should not be an error, or you risk a live-lock.
1270 struct request *blk_make_request(struct request_queue *q, struct bio *bio,
1273 struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
1278 blk_rq_set_block_pc(rq);
1281 struct bio *bounce_bio = bio;
1284 blk_queue_bounce(q, &bounce_bio);
1285 ret = blk_rq_append_bio(q, rq, bounce_bio);
1286 if (unlikely(ret)) {
1287 blk_put_request(rq);
1288 return ERR_PTR(ret);
1294 EXPORT_SYMBOL(blk_make_request);
1297 * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
1298 * @rq: request to be initialized
1301 void blk_rq_set_block_pc(struct request *rq)
1303 rq->cmd_type = REQ_TYPE_BLOCK_PC;
1305 rq->__sector = (sector_t) -1;
1306 rq->bio = rq->biotail = NULL;
1307 memset(rq->__cmd, 0, sizeof(rq->__cmd));
1309 EXPORT_SYMBOL(blk_rq_set_block_pc);
1312 * blk_requeue_request - put a request back on queue
1313 * @q: request queue where request should be inserted
1314 * @rq: request to be inserted
1317 * Drivers often keep queueing requests until the hardware cannot accept
1318 * more, when that condition happens we need to put the request back
1319 * on the queue. Must be called with queue lock held.
1321 void blk_requeue_request(struct request_queue *q, struct request *rq)
1323 blk_delete_timer(rq);
1324 blk_clear_rq_complete(rq);
1325 trace_block_rq_requeue(q, rq);
1327 if (rq->cmd_flags & REQ_QUEUED)
1328 blk_queue_end_tag(q, rq);
1330 BUG_ON(blk_queued_rq(rq));
1332 elv_requeue_request(q, rq);
1334 EXPORT_SYMBOL(blk_requeue_request);
1336 static void add_acct_request(struct request_queue *q, struct request *rq,
1339 blk_account_io_start(rq, true);
1340 __elv_add_request(q, rq, where);
1343 static void part_round_stats_single(int cpu, struct hd_struct *part,
1348 if (now == part->stamp)
1351 inflight = part_in_flight(part);
1353 __part_stat_add(cpu, part, time_in_queue,
1354 inflight * (now - part->stamp));
1355 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1361 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1362 * @cpu: cpu number for stats access
1363 * @part: target partition
1365 * The average IO queue length and utilisation statistics are maintained
1366 * by observing the current state of the queue length and the amount of
1367 * time it has been in this state for.
1369 * Normally, that accounting is done on IO completion, but that can result
1370 * in more than a second's worth of IO being accounted for within any one
1371 * second, leading to >100% utilisation. To deal with that, we call this
1372 * function to do a round-off before returning the results when reading
1373 * /proc/diskstats. This accounts immediately for all queue usage up to
1374 * the current jiffies and restarts the counters again.
1376 void part_round_stats(int cpu, struct hd_struct *part)
1378 unsigned long now = jiffies;
1381 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1382 part_round_stats_single(cpu, part, now);
1384 EXPORT_SYMBOL_GPL(part_round_stats);
1387 static void blk_pm_put_request(struct request *rq)
1389 if (rq->q->dev && !(rq->cmd_flags & REQ_PM) && !--rq->q->nr_pending)
1390 pm_runtime_mark_last_busy(rq->q->dev);
1393 static inline void blk_pm_put_request(struct request *rq) {}
1397 * queue lock must be held
1399 void __blk_put_request(struct request_queue *q, struct request *req)
1405 blk_mq_free_request(req);
1409 blk_pm_put_request(req);
1411 elv_completed_request(q, req);
1413 /* this is a bio leak */
1414 WARN_ON(req->bio != NULL);
1417 * Request may not have originated from ll_rw_blk. if not,
1418 * it didn't come out of our reserved rq pools
1420 if (req->cmd_flags & REQ_ALLOCED) {
1421 unsigned int flags = req->cmd_flags;
1422 struct request_list *rl = blk_rq_rl(req);
1424 BUG_ON(!list_empty(&req->queuelist));
1425 BUG_ON(ELV_ON_HASH(req));
1427 blk_free_request(rl, req);
1428 freed_request(rl, flags);
1432 EXPORT_SYMBOL_GPL(__blk_put_request);
1434 void blk_put_request(struct request *req)
1436 struct request_queue *q = req->q;
1439 blk_mq_free_request(req);
1441 unsigned long flags;
1443 spin_lock_irqsave(q->queue_lock, flags);
1444 __blk_put_request(q, req);
1445 spin_unlock_irqrestore(q->queue_lock, flags);
1448 EXPORT_SYMBOL(blk_put_request);
1451 * blk_add_request_payload - add a payload to a request
1452 * @rq: request to update
1453 * @page: page backing the payload
1454 * @len: length of the payload.
1456 * This allows to later add a payload to an already submitted request by
1457 * a block driver. The driver needs to take care of freeing the payload
1460 * Note that this is a quite horrible hack and nothing but handling of
1461 * discard requests should ever use it.
1463 void blk_add_request_payload(struct request *rq, struct page *page,
1466 struct bio *bio = rq->bio;
1468 bio->bi_io_vec->bv_page = page;
1469 bio->bi_io_vec->bv_offset = 0;
1470 bio->bi_io_vec->bv_len = len;
1472 bio->bi_iter.bi_size = len;
1474 bio->bi_phys_segments = 1;
1476 rq->__data_len = rq->resid_len = len;
1477 rq->nr_phys_segments = 1;
1479 EXPORT_SYMBOL_GPL(blk_add_request_payload);
1481 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
1484 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1486 if (!ll_back_merge_fn(q, req, bio))
1489 trace_block_bio_backmerge(q, req, bio);
1491 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1492 blk_rq_set_mixed_merge(req);
1494 req->biotail->bi_next = bio;
1496 req->__data_len += bio->bi_iter.bi_size;
1497 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1499 blk_account_io_start(req, false);
1503 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
1506 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1508 if (!ll_front_merge_fn(q, req, bio))
1511 trace_block_bio_frontmerge(q, req, bio);
1513 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1514 blk_rq_set_mixed_merge(req);
1516 bio->bi_next = req->bio;
1519 req->__sector = bio->bi_iter.bi_sector;
1520 req->__data_len += bio->bi_iter.bi_size;
1521 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1523 blk_account_io_start(req, false);
1528 * blk_attempt_plug_merge - try to merge with %current's plugged list
1529 * @q: request_queue new bio is being queued at
1530 * @bio: new bio being queued
1531 * @request_count: out parameter for number of traversed plugged requests
1533 * Determine whether @bio being queued on @q can be merged with a request
1534 * on %current's plugged list. Returns %true if merge was successful,
1537 * Plugging coalesces IOs from the same issuer for the same purpose without
1538 * going through @q->queue_lock. As such it's more of an issuing mechanism
1539 * than scheduling, and the request, while may have elvpriv data, is not
1540 * added on the elevator at this point. In addition, we don't have
1541 * reliable access to the elevator outside queue lock. Only check basic
1542 * merging parameters without querying the elevator.
1544 * Caller must ensure !blk_queue_nomerges(q) beforehand.
1546 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
1547 unsigned int *request_count,
1548 struct request **same_queue_rq)
1550 struct blk_plug *plug;
1553 struct list_head *plug_list;
1555 plug = current->plug;
1561 plug_list = &plug->mq_list;
1563 plug_list = &plug->list;
1565 list_for_each_entry_reverse(rq, plug_list, queuelist) {
1571 * Only blk-mq multiple hardware queues case checks the
1572 * rq in the same queue, there should be only one such
1576 *same_queue_rq = rq;
1579 if (rq->q != q || !blk_rq_merge_ok(rq, bio))
1582 el_ret = blk_try_merge(rq, bio);
1583 if (el_ret == ELEVATOR_BACK_MERGE) {
1584 ret = bio_attempt_back_merge(q, rq, bio);
1587 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1588 ret = bio_attempt_front_merge(q, rq, bio);
1597 unsigned int blk_plug_queued_count(struct request_queue *q)
1599 struct blk_plug *plug;
1601 struct list_head *plug_list;
1602 unsigned int ret = 0;
1604 plug = current->plug;
1609 plug_list = &plug->mq_list;
1611 plug_list = &plug->list;
1613 list_for_each_entry(rq, plug_list, queuelist) {
1621 void init_request_from_bio(struct request *req, struct bio *bio)
1623 req->cmd_type = REQ_TYPE_FS;
1625 req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK;
1626 if (bio->bi_rw & REQ_RAHEAD)
1627 req->cmd_flags |= REQ_FAILFAST_MASK;
1630 req->__sector = bio->bi_iter.bi_sector;
1631 req->ioprio = bio_prio(bio);
1632 blk_rq_bio_prep(req->q, req, bio);
1635 static void blk_queue_bio(struct request_queue *q, struct bio *bio)
1637 const bool sync = !!(bio->bi_rw & REQ_SYNC);
1638 struct blk_plug *plug;
1639 int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
1640 struct request *req;
1641 unsigned int request_count = 0;
1643 blk_queue_split(q, &bio, q->bio_split);
1646 * low level driver can indicate that it wants pages above a
1647 * certain limit bounced to low memory (ie for highmem, or even
1648 * ISA dma in theory)
1650 blk_queue_bounce(q, &bio);
1652 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1653 bio->bi_error = -EIO;
1658 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
1659 spin_lock_irq(q->queue_lock);
1660 where = ELEVATOR_INSERT_FLUSH;
1665 * Check if we can merge with the plugged list before grabbing
1668 if (!blk_queue_nomerges(q)) {
1669 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1672 request_count = blk_plug_queued_count(q);
1674 spin_lock_irq(q->queue_lock);
1676 el_ret = elv_merge(q, &req, bio);
1677 if (el_ret == ELEVATOR_BACK_MERGE) {
1678 if (bio_attempt_back_merge(q, req, bio)) {
1679 elv_bio_merged(q, req, bio);
1680 if (!attempt_back_merge(q, req))
1681 elv_merged_request(q, req, el_ret);
1684 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1685 if (bio_attempt_front_merge(q, req, bio)) {
1686 elv_bio_merged(q, req, bio);
1687 if (!attempt_front_merge(q, req))
1688 elv_merged_request(q, req, el_ret);
1695 * This sync check and mask will be re-done in init_request_from_bio(),
1696 * but we need to set it earlier to expose the sync flag to the
1697 * rq allocator and io schedulers.
1699 rw_flags = bio_data_dir(bio);
1701 rw_flags |= REQ_SYNC;
1704 * Grab a free request. This is might sleep but can not fail.
1705 * Returns with the queue unlocked.
1707 req = get_request(q, rw_flags, bio, GFP_NOIO);
1709 bio->bi_error = PTR_ERR(req);
1715 * After dropping the lock and possibly sleeping here, our request
1716 * may now be mergeable after it had proven unmergeable (above).
1717 * We don't worry about that case for efficiency. It won't happen
1718 * often, and the elevators are able to handle it.
1720 init_request_from_bio(req, bio);
1722 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
1723 req->cpu = raw_smp_processor_id();
1725 plug = current->plug;
1728 * If this is the first request added after a plug, fire
1732 trace_block_plug(q);
1734 if (request_count >= BLK_MAX_REQUEST_COUNT) {
1735 blk_flush_plug_list(plug, false);
1736 trace_block_plug(q);
1739 list_add_tail(&req->queuelist, &plug->list);
1740 blk_account_io_start(req, true);
1742 spin_lock_irq(q->queue_lock);
1743 add_acct_request(q, req, where);
1746 spin_unlock_irq(q->queue_lock);
1751 * If bio->bi_dev is a partition, remap the location
1753 static inline void blk_partition_remap(struct bio *bio)
1755 struct block_device *bdev = bio->bi_bdev;
1757 if (bio_sectors(bio) && bdev != bdev->bd_contains) {
1758 struct hd_struct *p = bdev->bd_part;
1760 bio->bi_iter.bi_sector += p->start_sect;
1761 bio->bi_bdev = bdev->bd_contains;
1763 trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
1765 bio->bi_iter.bi_sector - p->start_sect);
1769 static void handle_bad_sector(struct bio *bio)
1771 char b[BDEVNAME_SIZE];
1773 printk(KERN_INFO "attempt to access beyond end of device\n");
1774 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1775 bdevname(bio->bi_bdev, b),
1777 (unsigned long long)bio_end_sector(bio),
1778 (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
1781 #ifdef CONFIG_FAIL_MAKE_REQUEST
1783 static DECLARE_FAULT_ATTR(fail_make_request);
1785 static int __init setup_fail_make_request(char *str)
1787 return setup_fault_attr(&fail_make_request, str);
1789 __setup("fail_make_request=", setup_fail_make_request);
1791 static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
1793 return part->make_it_fail && should_fail(&fail_make_request, bytes);
1796 static int __init fail_make_request_debugfs(void)
1798 struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
1799 NULL, &fail_make_request);
1801 return PTR_ERR_OR_ZERO(dir);
1804 late_initcall(fail_make_request_debugfs);
1806 #else /* CONFIG_FAIL_MAKE_REQUEST */
1808 static inline bool should_fail_request(struct hd_struct *part,
1814 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1817 * Check whether this bio extends beyond the end of the device.
1819 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1826 /* Test device or partition size, when known. */
1827 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
1829 sector_t sector = bio->bi_iter.bi_sector;
1831 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1833 * This may well happen - the kernel calls bread()
1834 * without checking the size of the device, e.g., when
1835 * mounting a device.
1837 handle_bad_sector(bio);
1845 static noinline_for_stack bool
1846 generic_make_request_checks(struct bio *bio)
1848 struct request_queue *q;
1849 int nr_sectors = bio_sectors(bio);
1851 char b[BDEVNAME_SIZE];
1852 struct hd_struct *part;
1856 if (bio_check_eod(bio, nr_sectors))
1859 q = bdev_get_queue(bio->bi_bdev);
1862 "generic_make_request: Trying to access "
1863 "nonexistent block-device %s (%Lu)\n",
1864 bdevname(bio->bi_bdev, b),
1865 (long long) bio->bi_iter.bi_sector);
1869 part = bio->bi_bdev->bd_part;
1870 if (should_fail_request(part, bio->bi_iter.bi_size) ||
1871 should_fail_request(&part_to_disk(part)->part0,
1872 bio->bi_iter.bi_size))
1876 * If this device has partitions, remap block n
1877 * of partition p to block n+start(p) of the disk.
1879 blk_partition_remap(bio);
1881 if (bio_check_eod(bio, nr_sectors))
1885 * Filter flush bio's early so that make_request based
1886 * drivers without flush support don't have to worry
1889 if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
1890 bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
1897 if ((bio->bi_rw & REQ_DISCARD) &&
1898 (!blk_queue_discard(q) ||
1899 ((bio->bi_rw & REQ_SECURE) && !blk_queue_secdiscard(q)))) {
1904 if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) {
1910 * Various block parts want %current->io_context and lazy ioc
1911 * allocation ends up trading a lot of pain for a small amount of
1912 * memory. Just allocate it upfront. This may fail and block
1913 * layer knows how to live with it.
1915 create_io_context(GFP_ATOMIC, q->node);
1917 if (!blkcg_bio_issue_check(q, bio))
1920 trace_block_bio_queue(q, bio);
1924 bio->bi_error = err;
1930 * generic_make_request - hand a buffer to its device driver for I/O
1931 * @bio: The bio describing the location in memory and on the device.
1933 * generic_make_request() is used to make I/O requests of block
1934 * devices. It is passed a &struct bio, which describes the I/O that needs
1937 * generic_make_request() does not return any status. The
1938 * success/failure status of the request, along with notification of
1939 * completion, is delivered asynchronously through the bio->bi_end_io
1940 * function described (one day) else where.
1942 * The caller of generic_make_request must make sure that bi_io_vec
1943 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1944 * set to describe the device address, and the
1945 * bi_end_io and optionally bi_private are set to describe how
1946 * completion notification should be signaled.
1948 * generic_make_request and the drivers it calls may use bi_next if this
1949 * bio happens to be merged with someone else, and may resubmit the bio to
1950 * a lower device by calling into generic_make_request recursively, which
1951 * means the bio should NOT be touched after the call to ->make_request_fn.
1953 void generic_make_request(struct bio *bio)
1955 struct bio_list bio_list_on_stack;
1957 if (!generic_make_request_checks(bio))
1961 * We only want one ->make_request_fn to be active at a time, else
1962 * stack usage with stacked devices could be a problem. So use
1963 * current->bio_list to keep a list of requests submited by a
1964 * make_request_fn function. current->bio_list is also used as a
1965 * flag to say if generic_make_request is currently active in this
1966 * task or not. If it is NULL, then no make_request is active. If
1967 * it is non-NULL, then a make_request is active, and new requests
1968 * should be added at the tail
1970 if (current->bio_list) {
1971 bio_list_add(current->bio_list, bio);
1975 /* following loop may be a bit non-obvious, and so deserves some
1977 * Before entering the loop, bio->bi_next is NULL (as all callers
1978 * ensure that) so we have a list with a single bio.
1979 * We pretend that we have just taken it off a longer list, so
1980 * we assign bio_list to a pointer to the bio_list_on_stack,
1981 * thus initialising the bio_list of new bios to be
1982 * added. ->make_request() may indeed add some more bios
1983 * through a recursive call to generic_make_request. If it
1984 * did, we find a non-NULL value in bio_list and re-enter the loop
1985 * from the top. In this case we really did just take the bio
1986 * of the top of the list (no pretending) and so remove it from
1987 * bio_list, and call into ->make_request() again.
1989 BUG_ON(bio->bi_next);
1990 bio_list_init(&bio_list_on_stack);
1991 current->bio_list = &bio_list_on_stack;
1993 struct request_queue *q = bdev_get_queue(bio->bi_bdev);
1995 q->make_request_fn(q, bio);
1997 bio = bio_list_pop(current->bio_list);
1999 current->bio_list = NULL; /* deactivate */
2001 EXPORT_SYMBOL(generic_make_request);
2004 * submit_bio - submit a bio to the block device layer for I/O
2005 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
2006 * @bio: The &struct bio which describes the I/O
2008 * submit_bio() is very similar in purpose to generic_make_request(), and
2009 * uses that function to do most of the work. Both are fairly rough
2010 * interfaces; @bio must be presetup and ready for I/O.
2013 void submit_bio(int rw, struct bio *bio)
2018 * If it's a regular read/write or a barrier with data attached,
2019 * go through the normal accounting stuff before submission.
2021 if (bio_has_data(bio)) {
2024 if (unlikely(rw & REQ_WRITE_SAME))
2025 count = bdev_logical_block_size(bio->bi_bdev) >> 9;
2027 count = bio_sectors(bio);
2030 count_vm_events(PGPGOUT, count);
2032 task_io_account_read(bio->bi_iter.bi_size);
2033 count_vm_events(PGPGIN, count);
2036 if (unlikely(block_dump)) {
2037 char b[BDEVNAME_SIZE];
2038 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
2039 current->comm, task_pid_nr(current),
2040 (rw & WRITE) ? "WRITE" : "READ",
2041 (unsigned long long)bio->bi_iter.bi_sector,
2042 bdevname(bio->bi_bdev, b),
2047 generic_make_request(bio);
2049 EXPORT_SYMBOL(submit_bio);
2052 * blk_rq_check_limits - Helper function to check a request for the queue limit
2054 * @rq: the request being checked
2057 * @rq may have been made based on weaker limitations of upper-level queues
2058 * in request stacking drivers, and it may violate the limitation of @q.
2059 * Since the block layer and the underlying device driver trust @rq
2060 * after it is inserted to @q, it should be checked against @q before
2061 * the insertion using this generic function.
2063 * This function should also be useful for request stacking drivers
2064 * in some cases below, so export this function.
2065 * Request stacking drivers like request-based dm may change the queue
2066 * limits while requests are in the queue (e.g. dm's table swapping).
2067 * Such request stacking drivers should check those requests against
2068 * the new queue limits again when they dispatch those requests,
2069 * although such checkings are also done against the old queue limits
2070 * when submitting requests.
2072 int blk_rq_check_limits(struct request_queue *q, struct request *rq)
2074 if (!rq_mergeable(rq))
2077 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) {
2078 printk(KERN_ERR "%s: over max size limit.\n", __func__);
2083 * queue's settings related to segment counting like q->bounce_pfn
2084 * may differ from that of other stacking queues.
2085 * Recalculate it to check the request correctly on this queue's
2088 blk_recalc_rq_segments(rq);
2089 if (rq->nr_phys_segments > queue_max_segments(q)) {
2090 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
2096 EXPORT_SYMBOL_GPL(blk_rq_check_limits);
2099 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2100 * @q: the queue to submit the request
2101 * @rq: the request being queued
2103 int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
2105 unsigned long flags;
2106 int where = ELEVATOR_INSERT_BACK;
2108 if (blk_rq_check_limits(q, rq))
2112 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
2116 if (blk_queue_io_stat(q))
2117 blk_account_io_start(rq, true);
2118 blk_mq_insert_request(rq, false, true, true);
2122 spin_lock_irqsave(q->queue_lock, flags);
2123 if (unlikely(blk_queue_dying(q))) {
2124 spin_unlock_irqrestore(q->queue_lock, flags);
2129 * Submitting request must be dequeued before calling this function
2130 * because it will be linked to another request_queue
2132 BUG_ON(blk_queued_rq(rq));
2134 if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA))
2135 where = ELEVATOR_INSERT_FLUSH;
2137 add_acct_request(q, rq, where);
2138 if (where == ELEVATOR_INSERT_FLUSH)
2140 spin_unlock_irqrestore(q->queue_lock, flags);
2144 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
2147 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2148 * @rq: request to examine
2151 * A request could be merge of IOs which require different failure
2152 * handling. This function determines the number of bytes which
2153 * can be failed from the beginning of the request without
2154 * crossing into area which need to be retried further.
2157 * The number of bytes to fail.
2160 * queue_lock must be held.
2162 unsigned int blk_rq_err_bytes(const struct request *rq)
2164 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
2165 unsigned int bytes = 0;
2168 if (!(rq->cmd_flags & REQ_MIXED_MERGE))
2169 return blk_rq_bytes(rq);
2172 * Currently the only 'mixing' which can happen is between
2173 * different fastfail types. We can safely fail portions
2174 * which have all the failfast bits that the first one has -
2175 * the ones which are at least as eager to fail as the first
2178 for (bio = rq->bio; bio; bio = bio->bi_next) {
2179 if ((bio->bi_rw & ff) != ff)
2181 bytes += bio->bi_iter.bi_size;
2184 /* this could lead to infinite loop */
2185 BUG_ON(blk_rq_bytes(rq) && !bytes);
2188 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
2190 void blk_account_io_completion(struct request *req, unsigned int bytes)
2192 if (blk_do_io_stat(req)) {
2193 const int rw = rq_data_dir(req);
2194 struct hd_struct *part;
2197 cpu = part_stat_lock();
2199 part_stat_add(cpu, part, sectors[rw], bytes >> 9);
2204 void blk_account_io_done(struct request *req)
2207 * Account IO completion. flush_rq isn't accounted as a
2208 * normal IO on queueing nor completion. Accounting the
2209 * containing request is enough.
2211 if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
2212 unsigned long duration = jiffies - req->start_time;
2213 const int rw = rq_data_dir(req);
2214 struct hd_struct *part;
2217 cpu = part_stat_lock();
2220 part_stat_inc(cpu, part, ios[rw]);
2221 part_stat_add(cpu, part, ticks[rw], duration);
2222 part_round_stats(cpu, part);
2223 part_dec_in_flight(part, rw);
2225 hd_struct_put(part);
2232 * Don't process normal requests when queue is suspended
2233 * or in the process of suspending/resuming
2235 static struct request *blk_pm_peek_request(struct request_queue *q,
2238 if (q->dev && (q->rpm_status == RPM_SUSPENDED ||
2239 (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM))))
2245 static inline struct request *blk_pm_peek_request(struct request_queue *q,
2252 void blk_account_io_start(struct request *rq, bool new_io)
2254 struct hd_struct *part;
2255 int rw = rq_data_dir(rq);
2258 if (!blk_do_io_stat(rq))
2261 cpu = part_stat_lock();
2265 part_stat_inc(cpu, part, merges[rw]);
2267 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
2268 if (!hd_struct_try_get(part)) {
2270 * The partition is already being removed,
2271 * the request will be accounted on the disk only
2273 * We take a reference on disk->part0 although that
2274 * partition will never be deleted, so we can treat
2275 * it as any other partition.
2277 part = &rq->rq_disk->part0;
2278 hd_struct_get(part);
2280 part_round_stats(cpu, part);
2281 part_inc_in_flight(part, rw);
2289 * blk_peek_request - peek at the top of a request queue
2290 * @q: request queue to peek at
2293 * Return the request at the top of @q. The returned request
2294 * should be started using blk_start_request() before LLD starts
2298 * Pointer to the request at the top of @q if available. Null
2302 * queue_lock must be held.
2304 struct request *blk_peek_request(struct request_queue *q)
2309 while ((rq = __elv_next_request(q)) != NULL) {
2311 rq = blk_pm_peek_request(q, rq);
2315 if (!(rq->cmd_flags & REQ_STARTED)) {
2317 * This is the first time the device driver
2318 * sees this request (possibly after
2319 * requeueing). Notify IO scheduler.
2321 if (rq->cmd_flags & REQ_SORTED)
2322 elv_activate_rq(q, rq);
2325 * just mark as started even if we don't start
2326 * it, a request that has been delayed should
2327 * not be passed by new incoming requests
2329 rq->cmd_flags |= REQ_STARTED;
2330 trace_block_rq_issue(q, rq);
2333 if (!q->boundary_rq || q->boundary_rq == rq) {
2334 q->end_sector = rq_end_sector(rq);
2335 q->boundary_rq = NULL;
2338 if (rq->cmd_flags & REQ_DONTPREP)
2341 if (q->dma_drain_size && blk_rq_bytes(rq)) {
2343 * make sure space for the drain appears we
2344 * know we can do this because max_hw_segments
2345 * has been adjusted to be one fewer than the
2348 rq->nr_phys_segments++;
2354 ret = q->prep_rq_fn(q, rq);
2355 if (ret == BLKPREP_OK) {
2357 } else if (ret == BLKPREP_DEFER) {
2359 * the request may have been (partially) prepped.
2360 * we need to keep this request in the front to
2361 * avoid resource deadlock. REQ_STARTED will
2362 * prevent other fs requests from passing this one.
2364 if (q->dma_drain_size && blk_rq_bytes(rq) &&
2365 !(rq->cmd_flags & REQ_DONTPREP)) {
2367 * remove the space for the drain we added
2368 * so that we don't add it again
2370 --rq->nr_phys_segments;
2375 } else if (ret == BLKPREP_KILL) {
2376 rq->cmd_flags |= REQ_QUIET;
2378 * Mark this request as started so we don't trigger
2379 * any debug logic in the end I/O path.
2381 blk_start_request(rq);
2382 __blk_end_request_all(rq, -EIO);
2384 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
2391 EXPORT_SYMBOL(blk_peek_request);
2393 void blk_dequeue_request(struct request *rq)
2395 struct request_queue *q = rq->q;
2397 BUG_ON(list_empty(&rq->queuelist));
2398 BUG_ON(ELV_ON_HASH(rq));
2400 list_del_init(&rq->queuelist);
2403 * the time frame between a request being removed from the lists
2404 * and to it is freed is accounted as io that is in progress at
2407 if (blk_account_rq(rq)) {
2408 q->in_flight[rq_is_sync(rq)]++;
2409 set_io_start_time_ns(rq);
2414 * blk_start_request - start request processing on the driver
2415 * @req: request to dequeue
2418 * Dequeue @req and start timeout timer on it. This hands off the
2419 * request to the driver.
2421 * Block internal functions which don't want to start timer should
2422 * call blk_dequeue_request().
2425 * queue_lock must be held.
2427 void blk_start_request(struct request *req)
2429 blk_dequeue_request(req);
2432 * We are now handing the request to the hardware, initialize
2433 * resid_len to full count and add the timeout handler.
2435 req->resid_len = blk_rq_bytes(req);
2436 if (unlikely(blk_bidi_rq(req)))
2437 req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
2439 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
2442 EXPORT_SYMBOL(blk_start_request);
2445 * blk_fetch_request - fetch a request from a request queue
2446 * @q: request queue to fetch a request from
2449 * Return the request at the top of @q. The request is started on
2450 * return and LLD can start processing it immediately.
2453 * Pointer to the request at the top of @q if available. Null
2457 * queue_lock must be held.
2459 struct request *blk_fetch_request(struct request_queue *q)
2463 rq = blk_peek_request(q);
2465 blk_start_request(rq);
2468 EXPORT_SYMBOL(blk_fetch_request);
2471 * blk_update_request - Special helper function for request stacking drivers
2472 * @req: the request being processed
2473 * @error: %0 for success, < %0 for error
2474 * @nr_bytes: number of bytes to complete @req
2477 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2478 * the request structure even if @req doesn't have leftover.
2479 * If @req has leftover, sets it up for the next range of segments.
2481 * This special helper function is only for request stacking drivers
2482 * (e.g. request-based dm) so that they can handle partial completion.
2483 * Actual device drivers should use blk_end_request instead.
2485 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2486 * %false return from this function.
2489 * %false - this request doesn't have any more data
2490 * %true - this request has more data
2492 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
2496 trace_block_rq_complete(req->q, req, nr_bytes);
2502 * For fs requests, rq is just carrier of independent bio's
2503 * and each partial completion should be handled separately.
2504 * Reset per-request error on each partial completion.
2506 * TODO: tj: This is too subtle. It would be better to let
2507 * low level drivers do what they see fit.
2509 if (req->cmd_type == REQ_TYPE_FS)
2512 if (error && req->cmd_type == REQ_TYPE_FS &&
2513 !(req->cmd_flags & REQ_QUIET)) {
2518 error_type = "recoverable transport";
2521 error_type = "critical target";
2524 error_type = "critical nexus";
2527 error_type = "timeout";
2530 error_type = "critical space allocation";
2533 error_type = "critical medium";
2540 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
2541 __func__, error_type, req->rq_disk ?
2542 req->rq_disk->disk_name : "?",
2543 (unsigned long long)blk_rq_pos(req));
2547 blk_account_io_completion(req, nr_bytes);
2551 struct bio *bio = req->bio;
2552 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
2554 if (bio_bytes == bio->bi_iter.bi_size)
2555 req->bio = bio->bi_next;
2557 req_bio_endio(req, bio, bio_bytes, error);
2559 total_bytes += bio_bytes;
2560 nr_bytes -= bio_bytes;
2571 * Reset counters so that the request stacking driver
2572 * can find how many bytes remain in the request
2575 req->__data_len = 0;
2579 req->__data_len -= total_bytes;
2581 /* update sector only for requests with clear definition of sector */
2582 if (req->cmd_type == REQ_TYPE_FS)
2583 req->__sector += total_bytes >> 9;
2585 /* mixed attributes always follow the first bio */
2586 if (req->cmd_flags & REQ_MIXED_MERGE) {
2587 req->cmd_flags &= ~REQ_FAILFAST_MASK;
2588 req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
2592 * If total number of sectors is less than the first segment
2593 * size, something has gone terribly wrong.
2595 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
2596 blk_dump_rq_flags(req, "request botched");
2597 req->__data_len = blk_rq_cur_bytes(req);
2600 /* recalculate the number of segments */
2601 blk_recalc_rq_segments(req);
2605 EXPORT_SYMBOL_GPL(blk_update_request);
2607 static bool blk_update_bidi_request(struct request *rq, int error,
2608 unsigned int nr_bytes,
2609 unsigned int bidi_bytes)
2611 if (blk_update_request(rq, error, nr_bytes))
2614 /* Bidi request must be completed as a whole */
2615 if (unlikely(blk_bidi_rq(rq)) &&
2616 blk_update_request(rq->next_rq, error, bidi_bytes))
2619 if (blk_queue_add_random(rq->q))
2620 add_disk_randomness(rq->rq_disk);
2626 * blk_unprep_request - unprepare a request
2629 * This function makes a request ready for complete resubmission (or
2630 * completion). It happens only after all error handling is complete,
2631 * so represents the appropriate moment to deallocate any resources
2632 * that were allocated to the request in the prep_rq_fn. The queue
2633 * lock is held when calling this.
2635 void blk_unprep_request(struct request *req)
2637 struct request_queue *q = req->q;
2639 req->cmd_flags &= ~REQ_DONTPREP;
2640 if (q->unprep_rq_fn)
2641 q->unprep_rq_fn(q, req);
2643 EXPORT_SYMBOL_GPL(blk_unprep_request);
2646 * queue lock must be held
2648 void blk_finish_request(struct request *req, int error)
2650 if (req->cmd_flags & REQ_QUEUED)
2651 blk_queue_end_tag(req->q, req);
2653 BUG_ON(blk_queued_rq(req));
2655 if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
2656 laptop_io_completion(&req->q->backing_dev_info);
2658 blk_delete_timer(req);
2660 if (req->cmd_flags & REQ_DONTPREP)
2661 blk_unprep_request(req);
2663 blk_account_io_done(req);
2666 req->end_io(req, error);
2668 if (blk_bidi_rq(req))
2669 __blk_put_request(req->next_rq->q, req->next_rq);
2671 __blk_put_request(req->q, req);
2674 EXPORT_SYMBOL(blk_finish_request);
2677 * blk_end_bidi_request - Complete a bidi request
2678 * @rq: the request to complete
2679 * @error: %0 for success, < %0 for error
2680 * @nr_bytes: number of bytes to complete @rq
2681 * @bidi_bytes: number of bytes to complete @rq->next_rq
2684 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2685 * Drivers that supports bidi can safely call this member for any
2686 * type of request, bidi or uni. In the later case @bidi_bytes is
2690 * %false - we are done with this request
2691 * %true - still buffers pending for this request
2693 static bool blk_end_bidi_request(struct request *rq, int error,
2694 unsigned int nr_bytes, unsigned int bidi_bytes)
2696 struct request_queue *q = rq->q;
2697 unsigned long flags;
2699 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2702 spin_lock_irqsave(q->queue_lock, flags);
2703 blk_finish_request(rq, error);
2704 spin_unlock_irqrestore(q->queue_lock, flags);
2710 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2711 * @rq: the request to complete
2712 * @error: %0 for success, < %0 for error
2713 * @nr_bytes: number of bytes to complete @rq
2714 * @bidi_bytes: number of bytes to complete @rq->next_rq
2717 * Identical to blk_end_bidi_request() except that queue lock is
2718 * assumed to be locked on entry and remains so on return.
2721 * %false - we are done with this request
2722 * %true - still buffers pending for this request
2724 bool __blk_end_bidi_request(struct request *rq, int error,
2725 unsigned int nr_bytes, unsigned int bidi_bytes)
2727 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2730 blk_finish_request(rq, error);
2736 * blk_end_request - Helper function for drivers to complete the request.
2737 * @rq: the request being processed
2738 * @error: %0 for success, < %0 for error
2739 * @nr_bytes: number of bytes to complete
2742 * Ends I/O on a number of bytes attached to @rq.
2743 * If @rq has leftover, sets it up for the next range of segments.
2746 * %false - we are done with this request
2747 * %true - still buffers pending for this request
2749 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2751 return blk_end_bidi_request(rq, error, nr_bytes, 0);
2753 EXPORT_SYMBOL(blk_end_request);
2756 * blk_end_request_all - Helper function for drives to finish the request.
2757 * @rq: the request to finish
2758 * @error: %0 for success, < %0 for error
2761 * Completely finish @rq.
2763 void blk_end_request_all(struct request *rq, int error)
2766 unsigned int bidi_bytes = 0;
2768 if (unlikely(blk_bidi_rq(rq)))
2769 bidi_bytes = blk_rq_bytes(rq->next_rq);
2771 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2774 EXPORT_SYMBOL(blk_end_request_all);
2777 * blk_end_request_cur - Helper function to finish the current request chunk.
2778 * @rq: the request to finish the current chunk for
2779 * @error: %0 for success, < %0 for error
2782 * Complete the current consecutively mapped chunk from @rq.
2785 * %false - we are done with this request
2786 * %true - still buffers pending for this request
2788 bool blk_end_request_cur(struct request *rq, int error)
2790 return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2792 EXPORT_SYMBOL(blk_end_request_cur);
2795 * blk_end_request_err - Finish a request till the next failure boundary.
2796 * @rq: the request to finish till the next failure boundary for
2797 * @error: must be negative errno
2800 * Complete @rq till the next failure boundary.
2803 * %false - we are done with this request
2804 * %true - still buffers pending for this request
2806 bool blk_end_request_err(struct request *rq, int error)
2808 WARN_ON(error >= 0);
2809 return blk_end_request(rq, error, blk_rq_err_bytes(rq));
2811 EXPORT_SYMBOL_GPL(blk_end_request_err);
2814 * __blk_end_request - Helper function for drivers to complete the request.
2815 * @rq: the request being processed
2816 * @error: %0 for success, < %0 for error
2817 * @nr_bytes: number of bytes to complete
2820 * Must be called with queue lock held unlike blk_end_request().
2823 * %false - we are done with this request
2824 * %true - still buffers pending for this request
2826 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2828 return __blk_end_bidi_request(rq, error, nr_bytes, 0);
2830 EXPORT_SYMBOL(__blk_end_request);
2833 * __blk_end_request_all - Helper function for drives to finish the request.
2834 * @rq: the request to finish
2835 * @error: %0 for success, < %0 for error
2838 * Completely finish @rq. Must be called with queue lock held.
2840 void __blk_end_request_all(struct request *rq, int error)
2843 unsigned int bidi_bytes = 0;
2845 if (unlikely(blk_bidi_rq(rq)))
2846 bidi_bytes = blk_rq_bytes(rq->next_rq);
2848 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2851 EXPORT_SYMBOL(__blk_end_request_all);
2854 * __blk_end_request_cur - Helper function to finish the current request chunk.
2855 * @rq: the request to finish the current chunk for
2856 * @error: %0 for success, < %0 for error
2859 * Complete the current consecutively mapped chunk from @rq. Must
2860 * be called with queue lock held.
2863 * %false - we are done with this request
2864 * %true - still buffers pending for this request
2866 bool __blk_end_request_cur(struct request *rq, int error)
2868 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2870 EXPORT_SYMBOL(__blk_end_request_cur);
2873 * __blk_end_request_err - Finish a request till the next failure boundary.
2874 * @rq: the request to finish till the next failure boundary for
2875 * @error: must be negative errno
2878 * Complete @rq till the next failure boundary. Must be called
2879 * with queue lock held.
2882 * %false - we are done with this request
2883 * %true - still buffers pending for this request
2885 bool __blk_end_request_err(struct request *rq, int error)
2887 WARN_ON(error >= 0);
2888 return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
2890 EXPORT_SYMBOL_GPL(__blk_end_request_err);
2892 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2895 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2896 rq->cmd_flags |= bio->bi_rw & REQ_WRITE;
2898 if (bio_has_data(bio))
2899 rq->nr_phys_segments = bio_phys_segments(q, bio);
2901 rq->__data_len = bio->bi_iter.bi_size;
2902 rq->bio = rq->biotail = bio;
2905 rq->rq_disk = bio->bi_bdev->bd_disk;
2908 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2910 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2911 * @rq: the request to be flushed
2914 * Flush all pages in @rq.
2916 void rq_flush_dcache_pages(struct request *rq)
2918 struct req_iterator iter;
2919 struct bio_vec bvec;
2921 rq_for_each_segment(bvec, rq, iter)
2922 flush_dcache_page(bvec.bv_page);
2924 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
2928 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2929 * @q : the queue of the device being checked
2932 * Check if underlying low-level drivers of a device are busy.
2933 * If the drivers want to export their busy state, they must set own
2934 * exporting function using blk_queue_lld_busy() first.
2936 * Basically, this function is used only by request stacking drivers
2937 * to stop dispatching requests to underlying devices when underlying
2938 * devices are busy. This behavior helps more I/O merging on the queue
2939 * of the request stacking driver and prevents I/O throughput regression
2940 * on burst I/O load.
2943 * 0 - Not busy (The request stacking driver should dispatch request)
2944 * 1 - Busy (The request stacking driver should stop dispatching request)
2946 int blk_lld_busy(struct request_queue *q)
2949 return q->lld_busy_fn(q);
2953 EXPORT_SYMBOL_GPL(blk_lld_busy);
2956 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
2957 * @rq: the clone request to be cleaned up
2960 * Free all bios in @rq for a cloned request.
2962 void blk_rq_unprep_clone(struct request *rq)
2966 while ((bio = rq->bio) != NULL) {
2967 rq->bio = bio->bi_next;
2972 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
2975 * Copy attributes of the original request to the clone request.
2976 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
2978 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
2980 dst->cpu = src->cpu;
2981 dst->cmd_flags |= (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
2982 dst->cmd_type = src->cmd_type;
2983 dst->__sector = blk_rq_pos(src);
2984 dst->__data_len = blk_rq_bytes(src);
2985 dst->nr_phys_segments = src->nr_phys_segments;
2986 dst->ioprio = src->ioprio;
2987 dst->extra_len = src->extra_len;
2991 * blk_rq_prep_clone - Helper function to setup clone request
2992 * @rq: the request to be setup
2993 * @rq_src: original request to be cloned
2994 * @bs: bio_set that bios for clone are allocated from
2995 * @gfp_mask: memory allocation mask for bio
2996 * @bio_ctr: setup function to be called for each clone bio.
2997 * Returns %0 for success, non %0 for failure.
2998 * @data: private data to be passed to @bio_ctr
3001 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3002 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3003 * are not copied, and copying such parts is the caller's responsibility.
3004 * Also, pages which the original bios are pointing to are not copied
3005 * and the cloned bios just point same pages.
3006 * So cloned bios must be completed before original bios, which means
3007 * the caller must complete @rq before @rq_src.
3009 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
3010 struct bio_set *bs, gfp_t gfp_mask,
3011 int (*bio_ctr)(struct bio *, struct bio *, void *),
3014 struct bio *bio, *bio_src;
3019 __rq_for_each_bio(bio_src, rq_src) {
3020 bio = bio_clone_fast(bio_src, gfp_mask, bs);
3024 if (bio_ctr && bio_ctr(bio, bio_src, data))
3028 rq->biotail->bi_next = bio;
3031 rq->bio = rq->biotail = bio;
3034 __blk_rq_prep_clone(rq, rq_src);
3041 blk_rq_unprep_clone(rq);
3045 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
3047 int kblockd_schedule_work(struct work_struct *work)
3049 return queue_work(kblockd_workqueue, work);
3051 EXPORT_SYMBOL(kblockd_schedule_work);
3053 int kblockd_schedule_delayed_work(struct delayed_work *dwork,
3054 unsigned long delay)
3056 return queue_delayed_work(kblockd_workqueue, dwork, delay);
3058 EXPORT_SYMBOL(kblockd_schedule_delayed_work);
3060 int kblockd_schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
3061 unsigned long delay)
3063 return queue_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
3065 EXPORT_SYMBOL(kblockd_schedule_delayed_work_on);
3068 * blk_start_plug - initialize blk_plug and track it inside the task_struct
3069 * @plug: The &struct blk_plug that needs to be initialized
3072 * Tracking blk_plug inside the task_struct will help with auto-flushing the
3073 * pending I/O should the task end up blocking between blk_start_plug() and
3074 * blk_finish_plug(). This is important from a performance perspective, but
3075 * also ensures that we don't deadlock. For instance, if the task is blocking
3076 * for a memory allocation, memory reclaim could end up wanting to free a
3077 * page belonging to that request that is currently residing in our private
3078 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
3079 * this kind of deadlock.
3081 void blk_start_plug(struct blk_plug *plug)
3083 struct task_struct *tsk = current;
3086 * If this is a nested plug, don't actually assign it.
3091 INIT_LIST_HEAD(&plug->list);
3092 INIT_LIST_HEAD(&plug->mq_list);
3093 INIT_LIST_HEAD(&plug->cb_list);
3095 * Store ordering should not be needed here, since a potential
3096 * preempt will imply a full memory barrier
3100 EXPORT_SYMBOL(blk_start_plug);
3102 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
3104 struct request *rqa = container_of(a, struct request, queuelist);
3105 struct request *rqb = container_of(b, struct request, queuelist);
3107 return !(rqa->q < rqb->q ||
3108 (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
3112 * If 'from_schedule' is true, then postpone the dispatch of requests
3113 * until a safe kblockd context. We due this to avoid accidental big
3114 * additional stack usage in driver dispatch, in places where the originally
3115 * plugger did not intend it.
3117 static void queue_unplugged(struct request_queue *q, unsigned int depth,
3119 __releases(q->queue_lock)
3121 trace_block_unplug(q, depth, !from_schedule);
3124 blk_run_queue_async(q);
3127 spin_unlock(q->queue_lock);
3130 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
3132 LIST_HEAD(callbacks);
3134 while (!list_empty(&plug->cb_list)) {
3135 list_splice_init(&plug->cb_list, &callbacks);
3137 while (!list_empty(&callbacks)) {
3138 struct blk_plug_cb *cb = list_first_entry(&callbacks,
3141 list_del(&cb->list);
3142 cb->callback(cb, from_schedule);
3147 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
3150 struct blk_plug *plug = current->plug;
3151 struct blk_plug_cb *cb;
3156 list_for_each_entry(cb, &plug->cb_list, list)
3157 if (cb->callback == unplug && cb->data == data)
3160 /* Not currently on the callback list */
3161 BUG_ON(size < sizeof(*cb));
3162 cb = kzalloc(size, GFP_ATOMIC);
3165 cb->callback = unplug;
3166 list_add(&cb->list, &plug->cb_list);
3170 EXPORT_SYMBOL(blk_check_plugged);
3172 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
3174 struct request_queue *q;
3175 unsigned long flags;
3180 flush_plug_callbacks(plug, from_schedule);
3182 if (!list_empty(&plug->mq_list))
3183 blk_mq_flush_plug_list(plug, from_schedule);
3185 if (list_empty(&plug->list))
3188 list_splice_init(&plug->list, &list);
3190 list_sort(NULL, &list, plug_rq_cmp);
3196 * Save and disable interrupts here, to avoid doing it for every
3197 * queue lock we have to take.
3199 local_irq_save(flags);
3200 while (!list_empty(&list)) {
3201 rq = list_entry_rq(list.next);
3202 list_del_init(&rq->queuelist);
3206 * This drops the queue lock
3209 queue_unplugged(q, depth, from_schedule);
3212 spin_lock(q->queue_lock);
3216 * Short-circuit if @q is dead
3218 if (unlikely(blk_queue_dying(q))) {
3219 __blk_end_request_all(rq, -ENODEV);
3224 * rq is already accounted, so use raw insert
3226 if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA))
3227 __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
3229 __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
3235 * This drops the queue lock
3238 queue_unplugged(q, depth, from_schedule);
3240 local_irq_restore(flags);
3243 void blk_finish_plug(struct blk_plug *plug)
3245 if (plug != current->plug)
3247 blk_flush_plug_list(plug, false);
3249 current->plug = NULL;
3251 EXPORT_SYMBOL(blk_finish_plug);
3255 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3256 * @q: the queue of the device
3257 * @dev: the device the queue belongs to
3260 * Initialize runtime-PM-related fields for @q and start auto suspend for
3261 * @dev. Drivers that want to take advantage of request-based runtime PM
3262 * should call this function after @dev has been initialized, and its
3263 * request queue @q has been allocated, and runtime PM for it can not happen
3264 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3265 * cases, driver should call this function before any I/O has taken place.
3267 * This function takes care of setting up using auto suspend for the device,
3268 * the autosuspend delay is set to -1 to make runtime suspend impossible
3269 * until an updated value is either set by user or by driver. Drivers do
3270 * not need to touch other autosuspend settings.
3272 * The block layer runtime PM is request based, so only works for drivers
3273 * that use request as their IO unit instead of those directly use bio's.
3275 void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
3278 q->rpm_status = RPM_ACTIVE;
3279 pm_runtime_set_autosuspend_delay(q->dev, -1);
3280 pm_runtime_use_autosuspend(q->dev);
3282 EXPORT_SYMBOL(blk_pm_runtime_init);
3285 * blk_pre_runtime_suspend - Pre runtime suspend check
3286 * @q: the queue of the device
3289 * This function will check if runtime suspend is allowed for the device
3290 * by examining if there are any requests pending in the queue. If there
3291 * are requests pending, the device can not be runtime suspended; otherwise,
3292 * the queue's status will be updated to SUSPENDING and the driver can
3293 * proceed to suspend the device.
3295 * For the not allowed case, we mark last busy for the device so that
3296 * runtime PM core will try to autosuspend it some time later.
3298 * This function should be called near the start of the device's
3299 * runtime_suspend callback.
3302 * 0 - OK to runtime suspend the device
3303 * -EBUSY - Device should not be runtime suspended
3305 int blk_pre_runtime_suspend(struct request_queue *q)
3309 spin_lock_irq(q->queue_lock);
3310 if (q->nr_pending) {
3312 pm_runtime_mark_last_busy(q->dev);
3314 q->rpm_status = RPM_SUSPENDING;
3316 spin_unlock_irq(q->queue_lock);
3319 EXPORT_SYMBOL(blk_pre_runtime_suspend);
3322 * blk_post_runtime_suspend - Post runtime suspend processing
3323 * @q: the queue of the device
3324 * @err: return value of the device's runtime_suspend function
3327 * Update the queue's runtime status according to the return value of the
3328 * device's runtime suspend function and mark last busy for the device so
3329 * that PM core will try to auto suspend the device at a later time.
3331 * This function should be called near the end of the device's
3332 * runtime_suspend callback.
3334 void blk_post_runtime_suspend(struct request_queue *q, int err)
3336 spin_lock_irq(q->queue_lock);
3338 q->rpm_status = RPM_SUSPENDED;
3340 q->rpm_status = RPM_ACTIVE;
3341 pm_runtime_mark_last_busy(q->dev);
3343 spin_unlock_irq(q->queue_lock);
3345 EXPORT_SYMBOL(blk_post_runtime_suspend);
3348 * blk_pre_runtime_resume - Pre runtime resume processing
3349 * @q: the queue of the device
3352 * Update the queue's runtime status to RESUMING in preparation for the
3353 * runtime resume of the device.
3355 * This function should be called near the start of the device's
3356 * runtime_resume callback.
3358 void blk_pre_runtime_resume(struct request_queue *q)
3360 spin_lock_irq(q->queue_lock);
3361 q->rpm_status = RPM_RESUMING;
3362 spin_unlock_irq(q->queue_lock);
3364 EXPORT_SYMBOL(blk_pre_runtime_resume);
3367 * blk_post_runtime_resume - Post runtime resume processing
3368 * @q: the queue of the device
3369 * @err: return value of the device's runtime_resume function
3372 * Update the queue's runtime status according to the return value of the
3373 * device's runtime_resume function. If it is successfully resumed, process
3374 * the requests that are queued into the device's queue when it is resuming
3375 * and then mark last busy and initiate autosuspend for it.
3377 * This function should be called near the end of the device's
3378 * runtime_resume callback.
3380 void blk_post_runtime_resume(struct request_queue *q, int err)
3382 spin_lock_irq(q->queue_lock);
3384 q->rpm_status = RPM_ACTIVE;
3386 pm_runtime_mark_last_busy(q->dev);
3387 pm_request_autosuspend(q->dev);
3389 q->rpm_status = RPM_SUSPENDED;
3391 spin_unlock_irq(q->queue_lock);
3393 EXPORT_SYMBOL(blk_post_runtime_resume);
3396 int __init blk_dev_init(void)
3398 BUILD_BUG_ON(__REQ_NR_BITS > 8 *
3399 FIELD_SIZEOF(struct request, cmd_flags));
3401 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3402 kblockd_workqueue = alloc_workqueue("kblockd",
3403 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
3404 if (!kblockd_workqueue)
3405 panic("Failed to create kblockd\n");
3407 request_cachep = kmem_cache_create("blkdev_requests",
3408 sizeof(struct request), 0, SLAB_PANIC, NULL);
3410 blk_requestq_cachep = kmem_cache_create("blkdev_queue",
3411 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);