Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
[linux/fpc-iii.git] / block / blk-core.c
blobc00e0bdeab4ab4724c42b379717200d405d9c584
1 /*
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>
7 * - July2000
8 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
9 */
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>
21 #include <linux/mm.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>
36 #define CREATE_TRACE_POINTS
37 #include <trace/events/block.h>
39 #include "blk.h"
40 #include "blk-cgroup.h"
41 #include "blk-mq.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_unplug);
48 DEFINE_IDA(blk_queue_ida);
51 * For the allocated request tables
53 struct kmem_cache *request_cachep = NULL;
56 * For queue allocation
58 struct kmem_cache *blk_requestq_cachep;
61 * Controlling structure to kblockd
63 static struct workqueue_struct *kblockd_workqueue;
65 void blk_queue_congestion_threshold(struct request_queue *q)
67 int nr;
69 nr = q->nr_requests - (q->nr_requests / 8) + 1;
70 if (nr > q->nr_requests)
71 nr = q->nr_requests;
72 q->nr_congestion_on = nr;
74 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
75 if (nr < 1)
76 nr = 1;
77 q->nr_congestion_off = nr;
80 /**
81 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
82 * @bdev: device
84 * Locates the passed device's request queue and returns the address of its
85 * backing_dev_info
87 * Will return NULL if the request queue cannot be located.
89 struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
91 struct backing_dev_info *ret = NULL;
92 struct request_queue *q = bdev_get_queue(bdev);
94 if (q)
95 ret = &q->backing_dev_info;
96 return ret;
98 EXPORT_SYMBOL(blk_get_backing_dev_info);
100 void blk_rq_init(struct request_queue *q, struct request *rq)
102 memset(rq, 0, sizeof(*rq));
104 INIT_LIST_HEAD(&rq->queuelist);
105 INIT_LIST_HEAD(&rq->timeout_list);
106 rq->cpu = -1;
107 rq->q = q;
108 rq->__sector = (sector_t) -1;
109 INIT_HLIST_NODE(&rq->hash);
110 RB_CLEAR_NODE(&rq->rb_node);
111 rq->cmd = rq->__cmd;
112 rq->cmd_len = BLK_MAX_CDB;
113 rq->tag = -1;
114 rq->start_time = jiffies;
115 set_start_time_ns(rq);
116 rq->part = NULL;
118 EXPORT_SYMBOL(blk_rq_init);
120 static void req_bio_endio(struct request *rq, struct bio *bio,
121 unsigned int nbytes, int error)
123 if (error)
124 clear_bit(BIO_UPTODATE, &bio->bi_flags);
125 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
126 error = -EIO;
128 if (unlikely(rq->cmd_flags & REQ_QUIET))
129 set_bit(BIO_QUIET, &bio->bi_flags);
131 bio_advance(bio, nbytes);
133 /* don't actually finish bio if it's part of flush sequence */
134 if (bio->bi_iter.bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
135 bio_endio(bio, error);
138 void blk_dump_rq_flags(struct request *rq, char *msg)
140 int bit;
142 printk(KERN_INFO "%s: dev %s: type=%x, flags=%llx\n", msg,
143 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
144 (unsigned long long) rq->cmd_flags);
146 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
147 (unsigned long long)blk_rq_pos(rq),
148 blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
149 printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n",
150 rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq));
152 if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
153 printk(KERN_INFO " cdb: ");
154 for (bit = 0; bit < BLK_MAX_CDB; bit++)
155 printk("%02x ", rq->cmd[bit]);
156 printk("\n");
159 EXPORT_SYMBOL(blk_dump_rq_flags);
161 static void blk_delay_work(struct work_struct *work)
163 struct request_queue *q;
165 q = container_of(work, struct request_queue, delay_work.work);
166 spin_lock_irq(q->queue_lock);
167 __blk_run_queue(q);
168 spin_unlock_irq(q->queue_lock);
172 * blk_delay_queue - restart queueing after defined interval
173 * @q: The &struct request_queue in question
174 * @msecs: Delay in msecs
176 * Description:
177 * Sometimes queueing needs to be postponed for a little while, to allow
178 * resources to come back. This function will make sure that queueing is
179 * restarted around the specified time. Queue lock must be held.
181 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
183 if (likely(!blk_queue_dead(q)))
184 queue_delayed_work(kblockd_workqueue, &q->delay_work,
185 msecs_to_jiffies(msecs));
187 EXPORT_SYMBOL(blk_delay_queue);
190 * blk_start_queue - restart a previously stopped queue
191 * @q: The &struct request_queue in question
193 * Description:
194 * blk_start_queue() will clear the stop flag on the queue, and call
195 * the request_fn for the queue if it was in a stopped state when
196 * entered. Also see blk_stop_queue(). Queue lock must be held.
198 void blk_start_queue(struct request_queue *q)
200 WARN_ON(!irqs_disabled());
202 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
203 __blk_run_queue(q);
205 EXPORT_SYMBOL(blk_start_queue);
208 * blk_stop_queue - stop a queue
209 * @q: The &struct request_queue in question
211 * Description:
212 * The Linux block layer assumes that a block driver will consume all
213 * entries on the request queue when the request_fn strategy is called.
214 * Often this will not happen, because of hardware limitations (queue
215 * depth settings). If a device driver gets a 'queue full' response,
216 * or if it simply chooses not to queue more I/O at one point, it can
217 * call this function to prevent the request_fn from being called until
218 * the driver has signalled it's ready to go again. This happens by calling
219 * blk_start_queue() to restart queue operations. Queue lock must be held.
221 void blk_stop_queue(struct request_queue *q)
223 cancel_delayed_work(&q->delay_work);
224 queue_flag_set(QUEUE_FLAG_STOPPED, q);
226 EXPORT_SYMBOL(blk_stop_queue);
229 * blk_sync_queue - cancel any pending callbacks on a queue
230 * @q: the queue
232 * Description:
233 * The block layer may perform asynchronous callback activity
234 * on a queue, such as calling the unplug function after a timeout.
235 * A block device may call blk_sync_queue to ensure that any
236 * such activity is cancelled, thus allowing it to release resources
237 * that the callbacks might use. The caller must already have made sure
238 * that its ->make_request_fn will not re-add plugging prior to calling
239 * this function.
241 * This function does not cancel any asynchronous activity arising
242 * out of elevator or throttling code. That would require elevaotor_exit()
243 * and blkcg_exit_queue() to be called with queue lock initialized.
246 void blk_sync_queue(struct request_queue *q)
248 del_timer_sync(&q->timeout);
250 if (q->mq_ops) {
251 struct blk_mq_hw_ctx *hctx;
252 int i;
254 queue_for_each_hw_ctx(q, hctx, i)
255 cancel_delayed_work_sync(&hctx->delayed_work);
256 } else {
257 cancel_delayed_work_sync(&q->delay_work);
260 EXPORT_SYMBOL(blk_sync_queue);
263 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
264 * @q: The queue to run
266 * Description:
267 * Invoke request handling on a queue if there are any pending requests.
268 * May be used to restart request handling after a request has completed.
269 * This variant runs the queue whether or not the queue has been
270 * stopped. Must be called with the queue lock held and interrupts
271 * disabled. See also @blk_run_queue.
273 inline void __blk_run_queue_uncond(struct request_queue *q)
275 if (unlikely(blk_queue_dead(q)))
276 return;
279 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
280 * the queue lock internally. As a result multiple threads may be
281 * running such a request function concurrently. Keep track of the
282 * number of active request_fn invocations such that blk_drain_queue()
283 * can wait until all these request_fn calls have finished.
285 q->request_fn_active++;
286 q->request_fn(q);
287 q->request_fn_active--;
291 * __blk_run_queue - run a single device queue
292 * @q: The queue to run
294 * Description:
295 * See @blk_run_queue. This variant must be called with the queue lock
296 * held and interrupts disabled.
298 void __blk_run_queue(struct request_queue *q)
300 if (unlikely(blk_queue_stopped(q)))
301 return;
303 __blk_run_queue_uncond(q);
305 EXPORT_SYMBOL(__blk_run_queue);
308 * blk_run_queue_async - run a single device queue in workqueue context
309 * @q: The queue to run
311 * Description:
312 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
313 * of us. The caller must hold the queue lock.
315 void blk_run_queue_async(struct request_queue *q)
317 if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
318 mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
320 EXPORT_SYMBOL(blk_run_queue_async);
323 * blk_run_queue - run a single device queue
324 * @q: The queue to run
326 * Description:
327 * Invoke request handling on this queue, if it has pending work to do.
328 * May be used to restart queueing when a request has completed.
330 void blk_run_queue(struct request_queue *q)
332 unsigned long flags;
334 spin_lock_irqsave(q->queue_lock, flags);
335 __blk_run_queue(q);
336 spin_unlock_irqrestore(q->queue_lock, flags);
338 EXPORT_SYMBOL(blk_run_queue);
340 void blk_put_queue(struct request_queue *q)
342 kobject_put(&q->kobj);
344 EXPORT_SYMBOL(blk_put_queue);
347 * __blk_drain_queue - drain requests from request_queue
348 * @q: queue to drain
349 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
351 * Drain requests from @q. If @drain_all is set, all requests are drained.
352 * If not, only ELVPRIV requests are drained. The caller is responsible
353 * for ensuring that no new requests which need to be drained are queued.
355 static void __blk_drain_queue(struct request_queue *q, bool drain_all)
356 __releases(q->queue_lock)
357 __acquires(q->queue_lock)
359 int i;
361 lockdep_assert_held(q->queue_lock);
363 while (true) {
364 bool drain = false;
367 * The caller might be trying to drain @q before its
368 * elevator is initialized.
370 if (q->elevator)
371 elv_drain_elevator(q);
373 blkcg_drain_queue(q);
376 * This function might be called on a queue which failed
377 * driver init after queue creation or is not yet fully
378 * active yet. Some drivers (e.g. fd and loop) get unhappy
379 * in such cases. Kick queue iff dispatch queue has
380 * something on it and @q has request_fn set.
382 if (!list_empty(&q->queue_head) && q->request_fn)
383 __blk_run_queue(q);
385 drain |= q->nr_rqs_elvpriv;
386 drain |= q->request_fn_active;
389 * Unfortunately, requests are queued at and tracked from
390 * multiple places and there's no single counter which can
391 * be drained. Check all the queues and counters.
393 if (drain_all) {
394 drain |= !list_empty(&q->queue_head);
395 for (i = 0; i < 2; i++) {
396 drain |= q->nr_rqs[i];
397 drain |= q->in_flight[i];
398 drain |= !list_empty(&q->flush_queue[i]);
402 if (!drain)
403 break;
405 spin_unlock_irq(q->queue_lock);
407 msleep(10);
409 spin_lock_irq(q->queue_lock);
413 * With queue marked dead, any woken up waiter will fail the
414 * allocation path, so the wakeup chaining is lost and we're
415 * left with hung waiters. We need to wake up those waiters.
417 if (q->request_fn) {
418 struct request_list *rl;
420 blk_queue_for_each_rl(rl, q)
421 for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
422 wake_up_all(&rl->wait[i]);
427 * blk_queue_bypass_start - enter queue bypass mode
428 * @q: queue of interest
430 * In bypass mode, only the dispatch FIFO queue of @q is used. This
431 * function makes @q enter bypass mode and drains all requests which were
432 * throttled or issued before. On return, it's guaranteed that no request
433 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
434 * inside queue or RCU read lock.
436 void blk_queue_bypass_start(struct request_queue *q)
438 bool drain;
440 spin_lock_irq(q->queue_lock);
441 drain = !q->bypass_depth++;
442 queue_flag_set(QUEUE_FLAG_BYPASS, q);
443 spin_unlock_irq(q->queue_lock);
445 if (drain) {
446 spin_lock_irq(q->queue_lock);
447 __blk_drain_queue(q, false);
448 spin_unlock_irq(q->queue_lock);
450 /* ensure blk_queue_bypass() is %true inside RCU read lock */
451 synchronize_rcu();
454 EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
457 * blk_queue_bypass_end - leave queue bypass mode
458 * @q: queue of interest
460 * Leave bypass mode and restore the normal queueing behavior.
462 void blk_queue_bypass_end(struct request_queue *q)
464 spin_lock_irq(q->queue_lock);
465 if (!--q->bypass_depth)
466 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
467 WARN_ON_ONCE(q->bypass_depth < 0);
468 spin_unlock_irq(q->queue_lock);
470 EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
473 * blk_cleanup_queue - shutdown a request queue
474 * @q: request queue to shutdown
476 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
477 * put it. All future requests will be failed immediately with -ENODEV.
479 void blk_cleanup_queue(struct request_queue *q)
481 spinlock_t *lock = q->queue_lock;
483 /* mark @q DYING, no new request or merges will be allowed afterwards */
484 mutex_lock(&q->sysfs_lock);
485 queue_flag_set_unlocked(QUEUE_FLAG_DYING, q);
486 spin_lock_irq(lock);
489 * A dying queue is permanently in bypass mode till released. Note
490 * that, unlike blk_queue_bypass_start(), we aren't performing
491 * synchronize_rcu() after entering bypass mode to avoid the delay
492 * as some drivers create and destroy a lot of queues while
493 * probing. This is still safe because blk_release_queue() will be
494 * called only after the queue refcnt drops to zero and nothing,
495 * RCU or not, would be traversing the queue by then.
497 q->bypass_depth++;
498 queue_flag_set(QUEUE_FLAG_BYPASS, q);
500 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
501 queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
502 queue_flag_set(QUEUE_FLAG_DYING, q);
503 spin_unlock_irq(lock);
504 mutex_unlock(&q->sysfs_lock);
507 * Drain all requests queued before DYING marking. Set DEAD flag to
508 * prevent that q->request_fn() gets invoked after draining finished.
510 if (q->mq_ops) {
511 blk_mq_drain_queue(q);
512 spin_lock_irq(lock);
513 } else {
514 spin_lock_irq(lock);
515 __blk_drain_queue(q, true);
517 queue_flag_set(QUEUE_FLAG_DEAD, q);
518 spin_unlock_irq(lock);
520 /* @q won't process any more request, flush async actions */
521 del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
522 blk_sync_queue(q);
524 spin_lock_irq(lock);
525 if (q->queue_lock != &q->__queue_lock)
526 q->queue_lock = &q->__queue_lock;
527 spin_unlock_irq(lock);
529 /* @q is and will stay empty, shutdown and put */
530 blk_put_queue(q);
532 EXPORT_SYMBOL(blk_cleanup_queue);
534 int blk_init_rl(struct request_list *rl, struct request_queue *q,
535 gfp_t gfp_mask)
537 if (unlikely(rl->rq_pool))
538 return 0;
540 rl->q = q;
541 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
542 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
543 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
544 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
546 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
547 mempool_free_slab, request_cachep,
548 gfp_mask, q->node);
549 if (!rl->rq_pool)
550 return -ENOMEM;
552 return 0;
555 void blk_exit_rl(struct request_list *rl)
557 if (rl->rq_pool)
558 mempool_destroy(rl->rq_pool);
561 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
563 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
565 EXPORT_SYMBOL(blk_alloc_queue);
567 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
569 struct request_queue *q;
570 int err;
572 q = kmem_cache_alloc_node(blk_requestq_cachep,
573 gfp_mask | __GFP_ZERO, node_id);
574 if (!q)
575 return NULL;
577 if (percpu_counter_init(&q->mq_usage_counter, 0))
578 goto fail_q;
580 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
581 if (q->id < 0)
582 goto fail_c;
584 q->backing_dev_info.ra_pages =
585 (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
586 q->backing_dev_info.state = 0;
587 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
588 q->backing_dev_info.name = "block";
589 q->node = node_id;
591 err = bdi_init(&q->backing_dev_info);
592 if (err)
593 goto fail_id;
595 setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
596 laptop_mode_timer_fn, (unsigned long) q);
597 setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
598 INIT_LIST_HEAD(&q->queue_head);
599 INIT_LIST_HEAD(&q->timeout_list);
600 INIT_LIST_HEAD(&q->icq_list);
601 #ifdef CONFIG_BLK_CGROUP
602 INIT_LIST_HEAD(&q->blkg_list);
603 #endif
604 INIT_LIST_HEAD(&q->flush_queue[0]);
605 INIT_LIST_HEAD(&q->flush_queue[1]);
606 INIT_LIST_HEAD(&q->flush_data_in_flight);
607 INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
609 kobject_init(&q->kobj, &blk_queue_ktype);
611 mutex_init(&q->sysfs_lock);
612 spin_lock_init(&q->__queue_lock);
615 * By default initialize queue_lock to internal lock and driver can
616 * override it later if need be.
618 q->queue_lock = &q->__queue_lock;
621 * A queue starts its life with bypass turned on to avoid
622 * unnecessary bypass on/off overhead and nasty surprises during
623 * init. The initial bypass will be finished when the queue is
624 * registered by blk_register_queue().
626 q->bypass_depth = 1;
627 __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
629 init_waitqueue_head(&q->mq_freeze_wq);
631 if (blkcg_init_queue(q))
632 goto fail_bdi;
634 return q;
636 fail_bdi:
637 bdi_destroy(&q->backing_dev_info);
638 fail_id:
639 ida_simple_remove(&blk_queue_ida, q->id);
640 fail_c:
641 percpu_counter_destroy(&q->mq_usage_counter);
642 fail_q:
643 kmem_cache_free(blk_requestq_cachep, q);
644 return NULL;
646 EXPORT_SYMBOL(blk_alloc_queue_node);
649 * blk_init_queue - prepare a request queue for use with a block device
650 * @rfn: The function to be called to process requests that have been
651 * placed on the queue.
652 * @lock: Request queue spin lock
654 * Description:
655 * If a block device wishes to use the standard request handling procedures,
656 * which sorts requests and coalesces adjacent requests, then it must
657 * call blk_init_queue(). The function @rfn will be called when there
658 * are requests on the queue that need to be processed. If the device
659 * supports plugging, then @rfn may not be called immediately when requests
660 * are available on the queue, but may be called at some time later instead.
661 * Plugged queues are generally unplugged when a buffer belonging to one
662 * of the requests on the queue is needed, or due to memory pressure.
664 * @rfn is not required, or even expected, to remove all requests off the
665 * queue, but only as many as it can handle at a time. If it does leave
666 * requests on the queue, it is responsible for arranging that the requests
667 * get dealt with eventually.
669 * The queue spin lock must be held while manipulating the requests on the
670 * request queue; this lock will be taken also from interrupt context, so irq
671 * disabling is needed for it.
673 * Function returns a pointer to the initialized request queue, or %NULL if
674 * it didn't succeed.
676 * Note:
677 * blk_init_queue() must be paired with a blk_cleanup_queue() call
678 * when the block device is deactivated (such as at module unload).
681 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
683 return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
685 EXPORT_SYMBOL(blk_init_queue);
687 struct request_queue *
688 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
690 struct request_queue *uninit_q, *q;
692 uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
693 if (!uninit_q)
694 return NULL;
696 q = blk_init_allocated_queue(uninit_q, rfn, lock);
697 if (!q)
698 blk_cleanup_queue(uninit_q);
700 return q;
702 EXPORT_SYMBOL(blk_init_queue_node);
704 struct request_queue *
705 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
706 spinlock_t *lock)
708 if (!q)
709 return NULL;
711 if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
712 return NULL;
714 q->request_fn = rfn;
715 q->prep_rq_fn = NULL;
716 q->unprep_rq_fn = NULL;
717 q->queue_flags |= QUEUE_FLAG_DEFAULT;
719 /* Override internal queue lock with supplied lock pointer */
720 if (lock)
721 q->queue_lock = lock;
724 * This also sets hw/phys segments, boundary and size
726 blk_queue_make_request(q, blk_queue_bio);
728 q->sg_reserved_size = INT_MAX;
730 /* Protect q->elevator from elevator_change */
731 mutex_lock(&q->sysfs_lock);
733 /* init elevator */
734 if (elevator_init(q, NULL)) {
735 mutex_unlock(&q->sysfs_lock);
736 return NULL;
739 mutex_unlock(&q->sysfs_lock);
741 return q;
743 EXPORT_SYMBOL(blk_init_allocated_queue);
745 bool blk_get_queue(struct request_queue *q)
747 if (likely(!blk_queue_dying(q))) {
748 __blk_get_queue(q);
749 return true;
752 return false;
754 EXPORT_SYMBOL(blk_get_queue);
756 static inline void blk_free_request(struct request_list *rl, struct request *rq)
758 if (rq->cmd_flags & REQ_ELVPRIV) {
759 elv_put_request(rl->q, rq);
760 if (rq->elv.icq)
761 put_io_context(rq->elv.icq->ioc);
764 mempool_free(rq, rl->rq_pool);
768 * ioc_batching returns true if the ioc is a valid batching request and
769 * should be given priority access to a request.
771 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
773 if (!ioc)
774 return 0;
777 * Make sure the process is able to allocate at least 1 request
778 * even if the batch times out, otherwise we could theoretically
779 * lose wakeups.
781 return ioc->nr_batch_requests == q->nr_batching ||
782 (ioc->nr_batch_requests > 0
783 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
787 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
788 * will cause the process to be a "batcher" on all queues in the system. This
789 * is the behaviour we want though - once it gets a wakeup it should be given
790 * a nice run.
792 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
794 if (!ioc || ioc_batching(q, ioc))
795 return;
797 ioc->nr_batch_requests = q->nr_batching;
798 ioc->last_waited = jiffies;
801 static void __freed_request(struct request_list *rl, int sync)
803 struct request_queue *q = rl->q;
806 * bdi isn't aware of blkcg yet. As all async IOs end up root
807 * blkcg anyway, just use root blkcg state.
809 if (rl == &q->root_rl &&
810 rl->count[sync] < queue_congestion_off_threshold(q))
811 blk_clear_queue_congested(q, sync);
813 if (rl->count[sync] + 1 <= q->nr_requests) {
814 if (waitqueue_active(&rl->wait[sync]))
815 wake_up(&rl->wait[sync]);
817 blk_clear_rl_full(rl, sync);
822 * A request has just been released. Account for it, update the full and
823 * congestion status, wake up any waiters. Called under q->queue_lock.
825 static void freed_request(struct request_list *rl, unsigned int flags)
827 struct request_queue *q = rl->q;
828 int sync = rw_is_sync(flags);
830 q->nr_rqs[sync]--;
831 rl->count[sync]--;
832 if (flags & REQ_ELVPRIV)
833 q->nr_rqs_elvpriv--;
835 __freed_request(rl, sync);
837 if (unlikely(rl->starved[sync ^ 1]))
838 __freed_request(rl, sync ^ 1);
842 * Determine if elevator data should be initialized when allocating the
843 * request associated with @bio.
845 static bool blk_rq_should_init_elevator(struct bio *bio)
847 if (!bio)
848 return true;
851 * Flush requests do not use the elevator so skip initialization.
852 * This allows a request to share the flush and elevator data.
854 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
855 return false;
857 return true;
861 * rq_ioc - determine io_context for request allocation
862 * @bio: request being allocated is for this bio (can be %NULL)
864 * Determine io_context to use for request allocation for @bio. May return
865 * %NULL if %current->io_context doesn't exist.
867 static struct io_context *rq_ioc(struct bio *bio)
869 #ifdef CONFIG_BLK_CGROUP
870 if (bio && bio->bi_ioc)
871 return bio->bi_ioc;
872 #endif
873 return current->io_context;
877 * __get_request - get a free request
878 * @rl: request list to allocate from
879 * @rw_flags: RW and SYNC flags
880 * @bio: bio to allocate request for (can be %NULL)
881 * @gfp_mask: allocation mask
883 * Get a free request from @q. This function may fail under memory
884 * pressure or if @q is dead.
886 * Must be callled with @q->queue_lock held and,
887 * Returns %NULL on failure, with @q->queue_lock held.
888 * Returns !%NULL on success, with @q->queue_lock *not held*.
890 static struct request *__get_request(struct request_list *rl, int rw_flags,
891 struct bio *bio, gfp_t gfp_mask)
893 struct request_queue *q = rl->q;
894 struct request *rq;
895 struct elevator_type *et = q->elevator->type;
896 struct io_context *ioc = rq_ioc(bio);
897 struct io_cq *icq = NULL;
898 const bool is_sync = rw_is_sync(rw_flags) != 0;
899 int may_queue;
901 if (unlikely(blk_queue_dying(q)))
902 return NULL;
904 may_queue = elv_may_queue(q, rw_flags);
905 if (may_queue == ELV_MQUEUE_NO)
906 goto rq_starved;
908 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
909 if (rl->count[is_sync]+1 >= q->nr_requests) {
911 * The queue will fill after this allocation, so set
912 * it as full, and mark this process as "batching".
913 * This process will be allowed to complete a batch of
914 * requests, others will be blocked.
916 if (!blk_rl_full(rl, is_sync)) {
917 ioc_set_batching(q, ioc);
918 blk_set_rl_full(rl, is_sync);
919 } else {
920 if (may_queue != ELV_MQUEUE_MUST
921 && !ioc_batching(q, ioc)) {
923 * The queue is full and the allocating
924 * process is not a "batcher", and not
925 * exempted by the IO scheduler
927 return NULL;
932 * bdi isn't aware of blkcg yet. As all async IOs end up
933 * root blkcg anyway, just use root blkcg state.
935 if (rl == &q->root_rl)
936 blk_set_queue_congested(q, is_sync);
940 * Only allow batching queuers to allocate up to 50% over the defined
941 * limit of requests, otherwise we could have thousands of requests
942 * allocated with any setting of ->nr_requests
944 if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
945 return NULL;
947 q->nr_rqs[is_sync]++;
948 rl->count[is_sync]++;
949 rl->starved[is_sync] = 0;
952 * Decide whether the new request will be managed by elevator. If
953 * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
954 * prevent the current elevator from being destroyed until the new
955 * request is freed. This guarantees icq's won't be destroyed and
956 * makes creating new ones safe.
958 * Also, lookup icq while holding queue_lock. If it doesn't exist,
959 * it will be created after releasing queue_lock.
961 if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
962 rw_flags |= REQ_ELVPRIV;
963 q->nr_rqs_elvpriv++;
964 if (et->icq_cache && ioc)
965 icq = ioc_lookup_icq(ioc, q);
968 if (blk_queue_io_stat(q))
969 rw_flags |= REQ_IO_STAT;
970 spin_unlock_irq(q->queue_lock);
972 /* allocate and init request */
973 rq = mempool_alloc(rl->rq_pool, gfp_mask);
974 if (!rq)
975 goto fail_alloc;
977 blk_rq_init(q, rq);
978 blk_rq_set_rl(rq, rl);
979 rq->cmd_flags = rw_flags | REQ_ALLOCED;
981 /* init elvpriv */
982 if (rw_flags & REQ_ELVPRIV) {
983 if (unlikely(et->icq_cache && !icq)) {
984 if (ioc)
985 icq = ioc_create_icq(ioc, q, gfp_mask);
986 if (!icq)
987 goto fail_elvpriv;
990 rq->elv.icq = icq;
991 if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
992 goto fail_elvpriv;
994 /* @rq->elv.icq holds io_context until @rq is freed */
995 if (icq)
996 get_io_context(icq->ioc);
998 out:
1000 * ioc may be NULL here, and ioc_batching will be false. That's
1001 * OK, if the queue is under the request limit then requests need
1002 * not count toward the nr_batch_requests limit. There will always
1003 * be some limit enforced by BLK_BATCH_TIME.
1005 if (ioc_batching(q, ioc))
1006 ioc->nr_batch_requests--;
1008 trace_block_getrq(q, bio, rw_flags & 1);
1009 return rq;
1011 fail_elvpriv:
1013 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1014 * and may fail indefinitely under memory pressure and thus
1015 * shouldn't stall IO. Treat this request as !elvpriv. This will
1016 * disturb iosched and blkcg but weird is bettern than dead.
1018 printk_ratelimited(KERN_WARNING "%s: request aux data allocation failed, iosched may be disturbed\n",
1019 dev_name(q->backing_dev_info.dev));
1021 rq->cmd_flags &= ~REQ_ELVPRIV;
1022 rq->elv.icq = NULL;
1024 spin_lock_irq(q->queue_lock);
1025 q->nr_rqs_elvpriv--;
1026 spin_unlock_irq(q->queue_lock);
1027 goto out;
1029 fail_alloc:
1031 * Allocation failed presumably due to memory. Undo anything we
1032 * might have messed up.
1034 * Allocating task should really be put onto the front of the wait
1035 * queue, but this is pretty rare.
1037 spin_lock_irq(q->queue_lock);
1038 freed_request(rl, rw_flags);
1041 * in the very unlikely event that allocation failed and no
1042 * requests for this direction was pending, mark us starved so that
1043 * freeing of a request in the other direction will notice
1044 * us. another possible fix would be to split the rq mempool into
1045 * READ and WRITE
1047 rq_starved:
1048 if (unlikely(rl->count[is_sync] == 0))
1049 rl->starved[is_sync] = 1;
1050 return NULL;
1054 * get_request - get a free request
1055 * @q: request_queue to allocate request from
1056 * @rw_flags: RW and SYNC flags
1057 * @bio: bio to allocate request for (can be %NULL)
1058 * @gfp_mask: allocation mask
1060 * Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this
1061 * function keeps retrying under memory pressure and fails iff @q is dead.
1063 * Must be callled with @q->queue_lock held and,
1064 * Returns %NULL on failure, with @q->queue_lock held.
1065 * Returns !%NULL on success, with @q->queue_lock *not held*.
1067 static struct request *get_request(struct request_queue *q, int rw_flags,
1068 struct bio *bio, gfp_t gfp_mask)
1070 const bool is_sync = rw_is_sync(rw_flags) != 0;
1071 DEFINE_WAIT(wait);
1072 struct request_list *rl;
1073 struct request *rq;
1075 rl = blk_get_rl(q, bio); /* transferred to @rq on success */
1076 retry:
1077 rq = __get_request(rl, rw_flags, bio, gfp_mask);
1078 if (rq)
1079 return rq;
1081 if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) {
1082 blk_put_rl(rl);
1083 return NULL;
1086 /* wait on @rl and retry */
1087 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
1088 TASK_UNINTERRUPTIBLE);
1090 trace_block_sleeprq(q, bio, rw_flags & 1);
1092 spin_unlock_irq(q->queue_lock);
1093 io_schedule();
1096 * After sleeping, we become a "batching" process and will be able
1097 * to allocate at least one request, and up to a big batch of them
1098 * for a small period time. See ioc_batching, ioc_set_batching
1100 ioc_set_batching(q, current->io_context);
1102 spin_lock_irq(q->queue_lock);
1103 finish_wait(&rl->wait[is_sync], &wait);
1105 goto retry;
1108 static struct request *blk_old_get_request(struct request_queue *q, int rw,
1109 gfp_t gfp_mask)
1111 struct request *rq;
1113 BUG_ON(rw != READ && rw != WRITE);
1115 /* create ioc upfront */
1116 create_io_context(gfp_mask, q->node);
1118 spin_lock_irq(q->queue_lock);
1119 rq = get_request(q, rw, NULL, gfp_mask);
1120 if (!rq)
1121 spin_unlock_irq(q->queue_lock);
1122 /* q->queue_lock is unlocked at this point */
1124 return rq;
1127 struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
1129 if (q->mq_ops)
1130 return blk_mq_alloc_request(q, rw, gfp_mask, false);
1131 else
1132 return blk_old_get_request(q, rw, gfp_mask);
1134 EXPORT_SYMBOL(blk_get_request);
1137 * blk_make_request - given a bio, allocate a corresponding struct request.
1138 * @q: target request queue
1139 * @bio: The bio describing the memory mappings that will be submitted for IO.
1140 * It may be a chained-bio properly constructed by block/bio layer.
1141 * @gfp_mask: gfp flags to be used for memory allocation
1143 * blk_make_request is the parallel of generic_make_request for BLOCK_PC
1144 * type commands. Where the struct request needs to be farther initialized by
1145 * the caller. It is passed a &struct bio, which describes the memory info of
1146 * the I/O transfer.
1148 * The caller of blk_make_request must make sure that bi_io_vec
1149 * are set to describe the memory buffers. That bio_data_dir() will return
1150 * the needed direction of the request. (And all bio's in the passed bio-chain
1151 * are properly set accordingly)
1153 * If called under none-sleepable conditions, mapped bio buffers must not
1154 * need bouncing, by calling the appropriate masked or flagged allocator,
1155 * suitable for the target device. Otherwise the call to blk_queue_bounce will
1156 * BUG.
1158 * WARNING: When allocating/cloning a bio-chain, careful consideration should be
1159 * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
1160 * anything but the first bio in the chain. Otherwise you risk waiting for IO
1161 * completion of a bio that hasn't been submitted yet, thus resulting in a
1162 * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
1163 * of bio_alloc(), as that avoids the mempool deadlock.
1164 * If possible a big IO should be split into smaller parts when allocation
1165 * fails. Partial allocation should not be an error, or you risk a live-lock.
1167 struct request *blk_make_request(struct request_queue *q, struct bio *bio,
1168 gfp_t gfp_mask)
1170 struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
1172 if (unlikely(!rq))
1173 return ERR_PTR(-ENOMEM);
1175 for_each_bio(bio) {
1176 struct bio *bounce_bio = bio;
1177 int ret;
1179 blk_queue_bounce(q, &bounce_bio);
1180 ret = blk_rq_append_bio(q, rq, bounce_bio);
1181 if (unlikely(ret)) {
1182 blk_put_request(rq);
1183 return ERR_PTR(ret);
1187 return rq;
1189 EXPORT_SYMBOL(blk_make_request);
1192 * blk_requeue_request - put a request back on queue
1193 * @q: request queue where request should be inserted
1194 * @rq: request to be inserted
1196 * Description:
1197 * Drivers often keep queueing requests until the hardware cannot accept
1198 * more, when that condition happens we need to put the request back
1199 * on the queue. Must be called with queue lock held.
1201 void blk_requeue_request(struct request_queue *q, struct request *rq)
1203 blk_delete_timer(rq);
1204 blk_clear_rq_complete(rq);
1205 trace_block_rq_requeue(q, rq);
1207 if (blk_rq_tagged(rq))
1208 blk_queue_end_tag(q, rq);
1210 BUG_ON(blk_queued_rq(rq));
1212 elv_requeue_request(q, rq);
1214 EXPORT_SYMBOL(blk_requeue_request);
1216 static void add_acct_request(struct request_queue *q, struct request *rq,
1217 int where)
1219 blk_account_io_start(rq, true);
1220 __elv_add_request(q, rq, where);
1223 static void part_round_stats_single(int cpu, struct hd_struct *part,
1224 unsigned long now)
1226 if (now == part->stamp)
1227 return;
1229 if (part_in_flight(part)) {
1230 __part_stat_add(cpu, part, time_in_queue,
1231 part_in_flight(part) * (now - part->stamp));
1232 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1234 part->stamp = now;
1238 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1239 * @cpu: cpu number for stats access
1240 * @part: target partition
1242 * The average IO queue length and utilisation statistics are maintained
1243 * by observing the current state of the queue length and the amount of
1244 * time it has been in this state for.
1246 * Normally, that accounting is done on IO completion, but that can result
1247 * in more than a second's worth of IO being accounted for within any one
1248 * second, leading to >100% utilisation. To deal with that, we call this
1249 * function to do a round-off before returning the results when reading
1250 * /proc/diskstats. This accounts immediately for all queue usage up to
1251 * the current jiffies and restarts the counters again.
1253 void part_round_stats(int cpu, struct hd_struct *part)
1255 unsigned long now = jiffies;
1257 if (part->partno)
1258 part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
1259 part_round_stats_single(cpu, part, now);
1261 EXPORT_SYMBOL_GPL(part_round_stats);
1263 #ifdef CONFIG_PM_RUNTIME
1264 static void blk_pm_put_request(struct request *rq)
1266 if (rq->q->dev && !(rq->cmd_flags & REQ_PM) && !--rq->q->nr_pending)
1267 pm_runtime_mark_last_busy(rq->q->dev);
1269 #else
1270 static inline void blk_pm_put_request(struct request *rq) {}
1271 #endif
1274 * queue lock must be held
1276 void __blk_put_request(struct request_queue *q, struct request *req)
1278 if (unlikely(!q))
1279 return;
1281 blk_pm_put_request(req);
1283 elv_completed_request(q, req);
1285 /* this is a bio leak */
1286 WARN_ON(req->bio != NULL);
1289 * Request may not have originated from ll_rw_blk. if not,
1290 * it didn't come out of our reserved rq pools
1292 if (req->cmd_flags & REQ_ALLOCED) {
1293 unsigned int flags = req->cmd_flags;
1294 struct request_list *rl = blk_rq_rl(req);
1296 BUG_ON(!list_empty(&req->queuelist));
1297 BUG_ON(!hlist_unhashed(&req->hash));
1299 blk_free_request(rl, req);
1300 freed_request(rl, flags);
1301 blk_put_rl(rl);
1304 EXPORT_SYMBOL_GPL(__blk_put_request);
1306 void blk_put_request(struct request *req)
1308 struct request_queue *q = req->q;
1310 if (q->mq_ops)
1311 blk_mq_free_request(req);
1312 else {
1313 unsigned long flags;
1315 spin_lock_irqsave(q->queue_lock, flags);
1316 __blk_put_request(q, req);
1317 spin_unlock_irqrestore(q->queue_lock, flags);
1320 EXPORT_SYMBOL(blk_put_request);
1323 * blk_add_request_payload - add a payload to a request
1324 * @rq: request to update
1325 * @page: page backing the payload
1326 * @len: length of the payload.
1328 * This allows to later add a payload to an already submitted request by
1329 * a block driver. The driver needs to take care of freeing the payload
1330 * itself.
1332 * Note that this is a quite horrible hack and nothing but handling of
1333 * discard requests should ever use it.
1335 void blk_add_request_payload(struct request *rq, struct page *page,
1336 unsigned int len)
1338 struct bio *bio = rq->bio;
1340 bio->bi_io_vec->bv_page = page;
1341 bio->bi_io_vec->bv_offset = 0;
1342 bio->bi_io_vec->bv_len = len;
1344 bio->bi_iter.bi_size = len;
1345 bio->bi_vcnt = 1;
1346 bio->bi_phys_segments = 1;
1348 rq->__data_len = rq->resid_len = len;
1349 rq->nr_phys_segments = 1;
1350 rq->buffer = bio_data(bio);
1352 EXPORT_SYMBOL_GPL(blk_add_request_payload);
1354 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
1355 struct bio *bio)
1357 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1359 if (!ll_back_merge_fn(q, req, bio))
1360 return false;
1362 trace_block_bio_backmerge(q, req, bio);
1364 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1365 blk_rq_set_mixed_merge(req);
1367 req->biotail->bi_next = bio;
1368 req->biotail = bio;
1369 req->__data_len += bio->bi_iter.bi_size;
1370 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1372 blk_account_io_start(req, false);
1373 return true;
1376 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
1377 struct bio *bio)
1379 const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
1381 if (!ll_front_merge_fn(q, req, bio))
1382 return false;
1384 trace_block_bio_frontmerge(q, req, bio);
1386 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1387 blk_rq_set_mixed_merge(req);
1389 bio->bi_next = req->bio;
1390 req->bio = bio;
1393 * may not be valid. if the low level driver said
1394 * it didn't need a bounce buffer then it better
1395 * not touch req->buffer either...
1397 req->buffer = bio_data(bio);
1398 req->__sector = bio->bi_iter.bi_sector;
1399 req->__data_len += bio->bi_iter.bi_size;
1400 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1402 blk_account_io_start(req, false);
1403 return true;
1407 * blk_attempt_plug_merge - try to merge with %current's plugged list
1408 * @q: request_queue new bio is being queued at
1409 * @bio: new bio being queued
1410 * @request_count: out parameter for number of traversed plugged requests
1412 * Determine whether @bio being queued on @q can be merged with a request
1413 * on %current's plugged list. Returns %true if merge was successful,
1414 * otherwise %false.
1416 * Plugging coalesces IOs from the same issuer for the same purpose without
1417 * going through @q->queue_lock. As such it's more of an issuing mechanism
1418 * than scheduling, and the request, while may have elvpriv data, is not
1419 * added on the elevator at this point. In addition, we don't have
1420 * reliable access to the elevator outside queue lock. Only check basic
1421 * merging parameters without querying the elevator.
1423 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
1424 unsigned int *request_count)
1426 struct blk_plug *plug;
1427 struct request *rq;
1428 bool ret = false;
1429 struct list_head *plug_list;
1431 if (blk_queue_nomerges(q))
1432 goto out;
1434 plug = current->plug;
1435 if (!plug)
1436 goto out;
1437 *request_count = 0;
1439 if (q->mq_ops)
1440 plug_list = &plug->mq_list;
1441 else
1442 plug_list = &plug->list;
1444 list_for_each_entry_reverse(rq, plug_list, queuelist) {
1445 int el_ret;
1447 if (rq->q == q)
1448 (*request_count)++;
1450 if (rq->q != q || !blk_rq_merge_ok(rq, bio))
1451 continue;
1453 el_ret = blk_try_merge(rq, bio);
1454 if (el_ret == ELEVATOR_BACK_MERGE) {
1455 ret = bio_attempt_back_merge(q, rq, bio);
1456 if (ret)
1457 break;
1458 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1459 ret = bio_attempt_front_merge(q, rq, bio);
1460 if (ret)
1461 break;
1464 out:
1465 return ret;
1468 void init_request_from_bio(struct request *req, struct bio *bio)
1470 req->cmd_type = REQ_TYPE_FS;
1472 req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK;
1473 if (bio->bi_rw & REQ_RAHEAD)
1474 req->cmd_flags |= REQ_FAILFAST_MASK;
1476 req->errors = 0;
1477 req->__sector = bio->bi_iter.bi_sector;
1478 req->ioprio = bio_prio(bio);
1479 blk_rq_bio_prep(req->q, req, bio);
1482 void blk_queue_bio(struct request_queue *q, struct bio *bio)
1484 const bool sync = !!(bio->bi_rw & REQ_SYNC);
1485 struct blk_plug *plug;
1486 int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
1487 struct request *req;
1488 unsigned int request_count = 0;
1491 * low level driver can indicate that it wants pages above a
1492 * certain limit bounced to low memory (ie for highmem, or even
1493 * ISA dma in theory)
1495 blk_queue_bounce(q, &bio);
1497 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1498 bio_endio(bio, -EIO);
1499 return;
1502 if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
1503 spin_lock_irq(q->queue_lock);
1504 where = ELEVATOR_INSERT_FLUSH;
1505 goto get_rq;
1509 * Check if we can merge with the plugged list before grabbing
1510 * any locks.
1512 if (blk_attempt_plug_merge(q, bio, &request_count))
1513 return;
1515 spin_lock_irq(q->queue_lock);
1517 el_ret = elv_merge(q, &req, bio);
1518 if (el_ret == ELEVATOR_BACK_MERGE) {
1519 if (bio_attempt_back_merge(q, req, bio)) {
1520 elv_bio_merged(q, req, bio);
1521 if (!attempt_back_merge(q, req))
1522 elv_merged_request(q, req, el_ret);
1523 goto out_unlock;
1525 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
1526 if (bio_attempt_front_merge(q, req, bio)) {
1527 elv_bio_merged(q, req, bio);
1528 if (!attempt_front_merge(q, req))
1529 elv_merged_request(q, req, el_ret);
1530 goto out_unlock;
1534 get_rq:
1536 * This sync check and mask will be re-done in init_request_from_bio(),
1537 * but we need to set it earlier to expose the sync flag to the
1538 * rq allocator and io schedulers.
1540 rw_flags = bio_data_dir(bio);
1541 if (sync)
1542 rw_flags |= REQ_SYNC;
1545 * Grab a free request. This is might sleep but can not fail.
1546 * Returns with the queue unlocked.
1548 req = get_request(q, rw_flags, bio, GFP_NOIO);
1549 if (unlikely(!req)) {
1550 bio_endio(bio, -ENODEV); /* @q is dead */
1551 goto out_unlock;
1555 * After dropping the lock and possibly sleeping here, our request
1556 * may now be mergeable after it had proven unmergeable (above).
1557 * We don't worry about that case for efficiency. It won't happen
1558 * often, and the elevators are able to handle it.
1560 init_request_from_bio(req, bio);
1562 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
1563 req->cpu = raw_smp_processor_id();
1565 plug = current->plug;
1566 if (plug) {
1568 * If this is the first request added after a plug, fire
1569 * of a plug trace.
1571 if (!request_count)
1572 trace_block_plug(q);
1573 else {
1574 if (request_count >= BLK_MAX_REQUEST_COUNT) {
1575 blk_flush_plug_list(plug, false);
1576 trace_block_plug(q);
1579 list_add_tail(&req->queuelist, &plug->list);
1580 blk_account_io_start(req, true);
1581 } else {
1582 spin_lock_irq(q->queue_lock);
1583 add_acct_request(q, req, where);
1584 __blk_run_queue(q);
1585 out_unlock:
1586 spin_unlock_irq(q->queue_lock);
1589 EXPORT_SYMBOL_GPL(blk_queue_bio); /* for device mapper only */
1592 * If bio->bi_dev is a partition, remap the location
1594 static inline void blk_partition_remap(struct bio *bio)
1596 struct block_device *bdev = bio->bi_bdev;
1598 if (bio_sectors(bio) && bdev != bdev->bd_contains) {
1599 struct hd_struct *p = bdev->bd_part;
1601 bio->bi_iter.bi_sector += p->start_sect;
1602 bio->bi_bdev = bdev->bd_contains;
1604 trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
1605 bdev->bd_dev,
1606 bio->bi_iter.bi_sector - p->start_sect);
1610 static void handle_bad_sector(struct bio *bio)
1612 char b[BDEVNAME_SIZE];
1614 printk(KERN_INFO "attempt to access beyond end of device\n");
1615 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
1616 bdevname(bio->bi_bdev, b),
1617 bio->bi_rw,
1618 (unsigned long long)bio_end_sector(bio),
1619 (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
1621 set_bit(BIO_EOF, &bio->bi_flags);
1624 #ifdef CONFIG_FAIL_MAKE_REQUEST
1626 static DECLARE_FAULT_ATTR(fail_make_request);
1628 static int __init setup_fail_make_request(char *str)
1630 return setup_fault_attr(&fail_make_request, str);
1632 __setup("fail_make_request=", setup_fail_make_request);
1634 static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
1636 return part->make_it_fail && should_fail(&fail_make_request, bytes);
1639 static int __init fail_make_request_debugfs(void)
1641 struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
1642 NULL, &fail_make_request);
1644 return IS_ERR(dir) ? PTR_ERR(dir) : 0;
1647 late_initcall(fail_make_request_debugfs);
1649 #else /* CONFIG_FAIL_MAKE_REQUEST */
1651 static inline bool should_fail_request(struct hd_struct *part,
1652 unsigned int bytes)
1654 return false;
1657 #endif /* CONFIG_FAIL_MAKE_REQUEST */
1660 * Check whether this bio extends beyond the end of the device.
1662 static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
1664 sector_t maxsector;
1666 if (!nr_sectors)
1667 return 0;
1669 /* Test device or partition size, when known. */
1670 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
1671 if (maxsector) {
1672 sector_t sector = bio->bi_iter.bi_sector;
1674 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
1676 * This may well happen - the kernel calls bread()
1677 * without checking the size of the device, e.g., when
1678 * mounting a device.
1680 handle_bad_sector(bio);
1681 return 1;
1685 return 0;
1688 static noinline_for_stack bool
1689 generic_make_request_checks(struct bio *bio)
1691 struct request_queue *q;
1692 int nr_sectors = bio_sectors(bio);
1693 int err = -EIO;
1694 char b[BDEVNAME_SIZE];
1695 struct hd_struct *part;
1697 might_sleep();
1699 if (bio_check_eod(bio, nr_sectors))
1700 goto end_io;
1702 q = bdev_get_queue(bio->bi_bdev);
1703 if (unlikely(!q)) {
1704 printk(KERN_ERR
1705 "generic_make_request: Trying to access "
1706 "nonexistent block-device %s (%Lu)\n",
1707 bdevname(bio->bi_bdev, b),
1708 (long long) bio->bi_iter.bi_sector);
1709 goto end_io;
1712 if (likely(bio_is_rw(bio) &&
1713 nr_sectors > queue_max_hw_sectors(q))) {
1714 printk(KERN_ERR "bio too big device %s (%u > %u)\n",
1715 bdevname(bio->bi_bdev, b),
1716 bio_sectors(bio),
1717 queue_max_hw_sectors(q));
1718 goto end_io;
1721 part = bio->bi_bdev->bd_part;
1722 if (should_fail_request(part, bio->bi_iter.bi_size) ||
1723 should_fail_request(&part_to_disk(part)->part0,
1724 bio->bi_iter.bi_size))
1725 goto end_io;
1728 * If this device has partitions, remap block n
1729 * of partition p to block n+start(p) of the disk.
1731 blk_partition_remap(bio);
1733 if (bio_check_eod(bio, nr_sectors))
1734 goto end_io;
1737 * Filter flush bio's early so that make_request based
1738 * drivers without flush support don't have to worry
1739 * about them.
1741 if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
1742 bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
1743 if (!nr_sectors) {
1744 err = 0;
1745 goto end_io;
1749 if ((bio->bi_rw & REQ_DISCARD) &&
1750 (!blk_queue_discard(q) ||
1751 ((bio->bi_rw & REQ_SECURE) && !blk_queue_secdiscard(q)))) {
1752 err = -EOPNOTSUPP;
1753 goto end_io;
1756 if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) {
1757 err = -EOPNOTSUPP;
1758 goto end_io;
1762 * Various block parts want %current->io_context and lazy ioc
1763 * allocation ends up trading a lot of pain for a small amount of
1764 * memory. Just allocate it upfront. This may fail and block
1765 * layer knows how to live with it.
1767 create_io_context(GFP_ATOMIC, q->node);
1769 if (blk_throtl_bio(q, bio))
1770 return false; /* throttled, will be resubmitted later */
1772 trace_block_bio_queue(q, bio);
1773 return true;
1775 end_io:
1776 bio_endio(bio, err);
1777 return false;
1781 * generic_make_request - hand a buffer to its device driver for I/O
1782 * @bio: The bio describing the location in memory and on the device.
1784 * generic_make_request() is used to make I/O requests of block
1785 * devices. It is passed a &struct bio, which describes the I/O that needs
1786 * to be done.
1788 * generic_make_request() does not return any status. The
1789 * success/failure status of the request, along with notification of
1790 * completion, is delivered asynchronously through the bio->bi_end_io
1791 * function described (one day) else where.
1793 * The caller of generic_make_request must make sure that bi_io_vec
1794 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1795 * set to describe the device address, and the
1796 * bi_end_io and optionally bi_private are set to describe how
1797 * completion notification should be signaled.
1799 * generic_make_request and the drivers it calls may use bi_next if this
1800 * bio happens to be merged with someone else, and may resubmit the bio to
1801 * a lower device by calling into generic_make_request recursively, which
1802 * means the bio should NOT be touched after the call to ->make_request_fn.
1804 void generic_make_request(struct bio *bio)
1806 struct bio_list bio_list_on_stack;
1808 if (!generic_make_request_checks(bio))
1809 return;
1812 * We only want one ->make_request_fn to be active at a time, else
1813 * stack usage with stacked devices could be a problem. So use
1814 * current->bio_list to keep a list of requests submited by a
1815 * make_request_fn function. current->bio_list is also used as a
1816 * flag to say if generic_make_request is currently active in this
1817 * task or not. If it is NULL, then no make_request is active. If
1818 * it is non-NULL, then a make_request is active, and new requests
1819 * should be added at the tail
1821 if (current->bio_list) {
1822 bio_list_add(current->bio_list, bio);
1823 return;
1826 /* following loop may be a bit non-obvious, and so deserves some
1827 * explanation.
1828 * Before entering the loop, bio->bi_next is NULL (as all callers
1829 * ensure that) so we have a list with a single bio.
1830 * We pretend that we have just taken it off a longer list, so
1831 * we assign bio_list to a pointer to the bio_list_on_stack,
1832 * thus initialising the bio_list of new bios to be
1833 * added. ->make_request() may indeed add some more bios
1834 * through a recursive call to generic_make_request. If it
1835 * did, we find a non-NULL value in bio_list and re-enter the loop
1836 * from the top. In this case we really did just take the bio
1837 * of the top of the list (no pretending) and so remove it from
1838 * bio_list, and call into ->make_request() again.
1840 BUG_ON(bio->bi_next);
1841 bio_list_init(&bio_list_on_stack);
1842 current->bio_list = &bio_list_on_stack;
1843 do {
1844 struct request_queue *q = bdev_get_queue(bio->bi_bdev);
1846 q->make_request_fn(q, bio);
1848 bio = bio_list_pop(current->bio_list);
1849 } while (bio);
1850 current->bio_list = NULL; /* deactivate */
1852 EXPORT_SYMBOL(generic_make_request);
1855 * submit_bio - submit a bio to the block device layer for I/O
1856 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
1857 * @bio: The &struct bio which describes the I/O
1859 * submit_bio() is very similar in purpose to generic_make_request(), and
1860 * uses that function to do most of the work. Both are fairly rough
1861 * interfaces; @bio must be presetup and ready for I/O.
1864 void submit_bio(int rw, struct bio *bio)
1866 bio->bi_rw |= rw;
1869 * If it's a regular read/write or a barrier with data attached,
1870 * go through the normal accounting stuff before submission.
1872 if (bio_has_data(bio)) {
1873 unsigned int count;
1875 if (unlikely(rw & REQ_WRITE_SAME))
1876 count = bdev_logical_block_size(bio->bi_bdev) >> 9;
1877 else
1878 count = bio_sectors(bio);
1880 if (rw & WRITE) {
1881 count_vm_events(PGPGOUT, count);
1882 } else {
1883 task_io_account_read(bio->bi_iter.bi_size);
1884 count_vm_events(PGPGIN, count);
1887 if (unlikely(block_dump)) {
1888 char b[BDEVNAME_SIZE];
1889 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
1890 current->comm, task_pid_nr(current),
1891 (rw & WRITE) ? "WRITE" : "READ",
1892 (unsigned long long)bio->bi_iter.bi_sector,
1893 bdevname(bio->bi_bdev, b),
1894 count);
1898 generic_make_request(bio);
1900 EXPORT_SYMBOL(submit_bio);
1903 * blk_rq_check_limits - Helper function to check a request for the queue limit
1904 * @q: the queue
1905 * @rq: the request being checked
1907 * Description:
1908 * @rq may have been made based on weaker limitations of upper-level queues
1909 * in request stacking drivers, and it may violate the limitation of @q.
1910 * Since the block layer and the underlying device driver trust @rq
1911 * after it is inserted to @q, it should be checked against @q before
1912 * the insertion using this generic function.
1914 * This function should also be useful for request stacking drivers
1915 * in some cases below, so export this function.
1916 * Request stacking drivers like request-based dm may change the queue
1917 * limits while requests are in the queue (e.g. dm's table swapping).
1918 * Such request stacking drivers should check those requests agaist
1919 * the new queue limits again when they dispatch those requests,
1920 * although such checkings are also done against the old queue limits
1921 * when submitting requests.
1923 int blk_rq_check_limits(struct request_queue *q, struct request *rq)
1925 if (!rq_mergeable(rq))
1926 return 0;
1928 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) {
1929 printk(KERN_ERR "%s: over max size limit.\n", __func__);
1930 return -EIO;
1934 * queue's settings related to segment counting like q->bounce_pfn
1935 * may differ from that of other stacking queues.
1936 * Recalculate it to check the request correctly on this queue's
1937 * limitation.
1939 blk_recalc_rq_segments(rq);
1940 if (rq->nr_phys_segments > queue_max_segments(q)) {
1941 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
1942 return -EIO;
1945 return 0;
1947 EXPORT_SYMBOL_GPL(blk_rq_check_limits);
1950 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1951 * @q: the queue to submit the request
1952 * @rq: the request being queued
1954 int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
1956 unsigned long flags;
1957 int where = ELEVATOR_INSERT_BACK;
1959 if (blk_rq_check_limits(q, rq))
1960 return -EIO;
1962 if (rq->rq_disk &&
1963 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
1964 return -EIO;
1966 spin_lock_irqsave(q->queue_lock, flags);
1967 if (unlikely(blk_queue_dying(q))) {
1968 spin_unlock_irqrestore(q->queue_lock, flags);
1969 return -ENODEV;
1973 * Submitting request must be dequeued before calling this function
1974 * because it will be linked to another request_queue
1976 BUG_ON(blk_queued_rq(rq));
1978 if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA))
1979 where = ELEVATOR_INSERT_FLUSH;
1981 add_acct_request(q, rq, where);
1982 if (where == ELEVATOR_INSERT_FLUSH)
1983 __blk_run_queue(q);
1984 spin_unlock_irqrestore(q->queue_lock, flags);
1986 return 0;
1988 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
1991 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
1992 * @rq: request to examine
1994 * Description:
1995 * A request could be merge of IOs which require different failure
1996 * handling. This function determines the number of bytes which
1997 * can be failed from the beginning of the request without
1998 * crossing into area which need to be retried further.
2000 * Return:
2001 * The number of bytes to fail.
2003 * Context:
2004 * queue_lock must be held.
2006 unsigned int blk_rq_err_bytes(const struct request *rq)
2008 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
2009 unsigned int bytes = 0;
2010 struct bio *bio;
2012 if (!(rq->cmd_flags & REQ_MIXED_MERGE))
2013 return blk_rq_bytes(rq);
2016 * Currently the only 'mixing' which can happen is between
2017 * different fastfail types. We can safely fail portions
2018 * which have all the failfast bits that the first one has -
2019 * the ones which are at least as eager to fail as the first
2020 * one.
2022 for (bio = rq->bio; bio; bio = bio->bi_next) {
2023 if ((bio->bi_rw & ff) != ff)
2024 break;
2025 bytes += bio->bi_iter.bi_size;
2028 /* this could lead to infinite loop */
2029 BUG_ON(blk_rq_bytes(rq) && !bytes);
2030 return bytes;
2032 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
2034 void blk_account_io_completion(struct request *req, unsigned int bytes)
2036 if (blk_do_io_stat(req)) {
2037 const int rw = rq_data_dir(req);
2038 struct hd_struct *part;
2039 int cpu;
2041 cpu = part_stat_lock();
2042 part = req->part;
2043 part_stat_add(cpu, part, sectors[rw], bytes >> 9);
2044 part_stat_unlock();
2048 void blk_account_io_done(struct request *req)
2051 * Account IO completion. flush_rq isn't accounted as a
2052 * normal IO on queueing nor completion. Accounting the
2053 * containing request is enough.
2055 if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
2056 unsigned long duration = jiffies - req->start_time;
2057 const int rw = rq_data_dir(req);
2058 struct hd_struct *part;
2059 int cpu;
2061 cpu = part_stat_lock();
2062 part = req->part;
2064 part_stat_inc(cpu, part, ios[rw]);
2065 part_stat_add(cpu, part, ticks[rw], duration);
2066 part_round_stats(cpu, part);
2067 part_dec_in_flight(part, rw);
2069 hd_struct_put(part);
2070 part_stat_unlock();
2074 #ifdef CONFIG_PM_RUNTIME
2076 * Don't process normal requests when queue is suspended
2077 * or in the process of suspending/resuming
2079 static struct request *blk_pm_peek_request(struct request_queue *q,
2080 struct request *rq)
2082 if (q->dev && (q->rpm_status == RPM_SUSPENDED ||
2083 (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM))))
2084 return NULL;
2085 else
2086 return rq;
2088 #else
2089 static inline struct request *blk_pm_peek_request(struct request_queue *q,
2090 struct request *rq)
2092 return rq;
2094 #endif
2096 void blk_account_io_start(struct request *rq, bool new_io)
2098 struct hd_struct *part;
2099 int rw = rq_data_dir(rq);
2100 int cpu;
2102 if (!blk_do_io_stat(rq))
2103 return;
2105 cpu = part_stat_lock();
2107 if (!new_io) {
2108 part = rq->part;
2109 part_stat_inc(cpu, part, merges[rw]);
2110 } else {
2111 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
2112 if (!hd_struct_try_get(part)) {
2114 * The partition is already being removed,
2115 * the request will be accounted on the disk only
2117 * We take a reference on disk->part0 although that
2118 * partition will never be deleted, so we can treat
2119 * it as any other partition.
2121 part = &rq->rq_disk->part0;
2122 hd_struct_get(part);
2124 part_round_stats(cpu, part);
2125 part_inc_in_flight(part, rw);
2126 rq->part = part;
2129 part_stat_unlock();
2133 * blk_peek_request - peek at the top of a request queue
2134 * @q: request queue to peek at
2136 * Description:
2137 * Return the request at the top of @q. The returned request
2138 * should be started using blk_start_request() before LLD starts
2139 * processing it.
2141 * Return:
2142 * Pointer to the request at the top of @q if available. Null
2143 * otherwise.
2145 * Context:
2146 * queue_lock must be held.
2148 struct request *blk_peek_request(struct request_queue *q)
2150 struct request *rq;
2151 int ret;
2153 while ((rq = __elv_next_request(q)) != NULL) {
2155 rq = blk_pm_peek_request(q, rq);
2156 if (!rq)
2157 break;
2159 if (!(rq->cmd_flags & REQ_STARTED)) {
2161 * This is the first time the device driver
2162 * sees this request (possibly after
2163 * requeueing). Notify IO scheduler.
2165 if (rq->cmd_flags & REQ_SORTED)
2166 elv_activate_rq(q, rq);
2169 * just mark as started even if we don't start
2170 * it, a request that has been delayed should
2171 * not be passed by new incoming requests
2173 rq->cmd_flags |= REQ_STARTED;
2174 trace_block_rq_issue(q, rq);
2177 if (!q->boundary_rq || q->boundary_rq == rq) {
2178 q->end_sector = rq_end_sector(rq);
2179 q->boundary_rq = NULL;
2182 if (rq->cmd_flags & REQ_DONTPREP)
2183 break;
2185 if (q->dma_drain_size && blk_rq_bytes(rq)) {
2187 * make sure space for the drain appears we
2188 * know we can do this because max_hw_segments
2189 * has been adjusted to be one fewer than the
2190 * device can handle
2192 rq->nr_phys_segments++;
2195 if (!q->prep_rq_fn)
2196 break;
2198 ret = q->prep_rq_fn(q, rq);
2199 if (ret == BLKPREP_OK) {
2200 break;
2201 } else if (ret == BLKPREP_DEFER) {
2203 * the request may have been (partially) prepped.
2204 * we need to keep this request in the front to
2205 * avoid resource deadlock. REQ_STARTED will
2206 * prevent other fs requests from passing this one.
2208 if (q->dma_drain_size && blk_rq_bytes(rq) &&
2209 !(rq->cmd_flags & REQ_DONTPREP)) {
2211 * remove the space for the drain we added
2212 * so that we don't add it again
2214 --rq->nr_phys_segments;
2217 rq = NULL;
2218 break;
2219 } else if (ret == BLKPREP_KILL) {
2220 rq->cmd_flags |= REQ_QUIET;
2222 * Mark this request as started so we don't trigger
2223 * any debug logic in the end I/O path.
2225 blk_start_request(rq);
2226 __blk_end_request_all(rq, -EIO);
2227 } else {
2228 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
2229 break;
2233 return rq;
2235 EXPORT_SYMBOL(blk_peek_request);
2237 void blk_dequeue_request(struct request *rq)
2239 struct request_queue *q = rq->q;
2241 BUG_ON(list_empty(&rq->queuelist));
2242 BUG_ON(ELV_ON_HASH(rq));
2244 list_del_init(&rq->queuelist);
2247 * the time frame between a request being removed from the lists
2248 * and to it is freed is accounted as io that is in progress at
2249 * the driver side.
2251 if (blk_account_rq(rq)) {
2252 q->in_flight[rq_is_sync(rq)]++;
2253 set_io_start_time_ns(rq);
2258 * blk_start_request - start request processing on the driver
2259 * @req: request to dequeue
2261 * Description:
2262 * Dequeue @req and start timeout timer on it. This hands off the
2263 * request to the driver.
2265 * Block internal functions which don't want to start timer should
2266 * call blk_dequeue_request().
2268 * Context:
2269 * queue_lock must be held.
2271 void blk_start_request(struct request *req)
2273 blk_dequeue_request(req);
2276 * We are now handing the request to the hardware, initialize
2277 * resid_len to full count and add the timeout handler.
2279 req->resid_len = blk_rq_bytes(req);
2280 if (unlikely(blk_bidi_rq(req)))
2281 req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
2283 BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
2284 blk_add_timer(req);
2286 EXPORT_SYMBOL(blk_start_request);
2289 * blk_fetch_request - fetch a request from a request queue
2290 * @q: request queue to fetch a request from
2292 * Description:
2293 * Return the request at the top of @q. The request is started on
2294 * return and LLD can start processing it immediately.
2296 * Return:
2297 * Pointer to the request at the top of @q if available. Null
2298 * otherwise.
2300 * Context:
2301 * queue_lock must be held.
2303 struct request *blk_fetch_request(struct request_queue *q)
2305 struct request *rq;
2307 rq = blk_peek_request(q);
2308 if (rq)
2309 blk_start_request(rq);
2310 return rq;
2312 EXPORT_SYMBOL(blk_fetch_request);
2315 * blk_update_request - Special helper function for request stacking drivers
2316 * @req: the request being processed
2317 * @error: %0 for success, < %0 for error
2318 * @nr_bytes: number of bytes to complete @req
2320 * Description:
2321 * Ends I/O on a number of bytes attached to @req, but doesn't complete
2322 * the request structure even if @req doesn't have leftover.
2323 * If @req has leftover, sets it up for the next range of segments.
2325 * This special helper function is only for request stacking drivers
2326 * (e.g. request-based dm) so that they can handle partial completion.
2327 * Actual device drivers should use blk_end_request instead.
2329 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
2330 * %false return from this function.
2332 * Return:
2333 * %false - this request doesn't have any more data
2334 * %true - this request has more data
2336 bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
2338 int total_bytes;
2340 if (!req->bio)
2341 return false;
2343 trace_block_rq_complete(req->q, req);
2346 * For fs requests, rq is just carrier of independent bio's
2347 * and each partial completion should be handled separately.
2348 * Reset per-request error on each partial completion.
2350 * TODO: tj: This is too subtle. It would be better to let
2351 * low level drivers do what they see fit.
2353 if (req->cmd_type == REQ_TYPE_FS)
2354 req->errors = 0;
2356 if (error && req->cmd_type == REQ_TYPE_FS &&
2357 !(req->cmd_flags & REQ_QUIET)) {
2358 char *error_type;
2360 switch (error) {
2361 case -ENOLINK:
2362 error_type = "recoverable transport";
2363 break;
2364 case -EREMOTEIO:
2365 error_type = "critical target";
2366 break;
2367 case -EBADE:
2368 error_type = "critical nexus";
2369 break;
2370 case -ETIMEDOUT:
2371 error_type = "timeout";
2372 break;
2373 case -ENOSPC:
2374 error_type = "critical space allocation";
2375 break;
2376 case -ENODATA:
2377 error_type = "critical medium";
2378 break;
2379 case -EIO:
2380 default:
2381 error_type = "I/O";
2382 break;
2384 printk_ratelimited(KERN_ERR "end_request: %s error, dev %s, sector %llu\n",
2385 error_type, req->rq_disk ?
2386 req->rq_disk->disk_name : "?",
2387 (unsigned long long)blk_rq_pos(req));
2391 blk_account_io_completion(req, nr_bytes);
2393 total_bytes = 0;
2394 while (req->bio) {
2395 struct bio *bio = req->bio;
2396 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
2398 if (bio_bytes == bio->bi_iter.bi_size)
2399 req->bio = bio->bi_next;
2401 req_bio_endio(req, bio, bio_bytes, error);
2403 total_bytes += bio_bytes;
2404 nr_bytes -= bio_bytes;
2406 if (!nr_bytes)
2407 break;
2411 * completely done
2413 if (!req->bio) {
2415 * Reset counters so that the request stacking driver
2416 * can find how many bytes remain in the request
2417 * later.
2419 req->__data_len = 0;
2420 return false;
2423 req->__data_len -= total_bytes;
2424 req->buffer = bio_data(req->bio);
2426 /* update sector only for requests with clear definition of sector */
2427 if (req->cmd_type == REQ_TYPE_FS)
2428 req->__sector += total_bytes >> 9;
2430 /* mixed attributes always follow the first bio */
2431 if (req->cmd_flags & REQ_MIXED_MERGE) {
2432 req->cmd_flags &= ~REQ_FAILFAST_MASK;
2433 req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
2437 * If total number of sectors is less than the first segment
2438 * size, something has gone terribly wrong.
2440 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
2441 blk_dump_rq_flags(req, "request botched");
2442 req->__data_len = blk_rq_cur_bytes(req);
2445 /* recalculate the number of segments */
2446 blk_recalc_rq_segments(req);
2448 return true;
2450 EXPORT_SYMBOL_GPL(blk_update_request);
2452 static bool blk_update_bidi_request(struct request *rq, int error,
2453 unsigned int nr_bytes,
2454 unsigned int bidi_bytes)
2456 if (blk_update_request(rq, error, nr_bytes))
2457 return true;
2459 /* Bidi request must be completed as a whole */
2460 if (unlikely(blk_bidi_rq(rq)) &&
2461 blk_update_request(rq->next_rq, error, bidi_bytes))
2462 return true;
2464 if (blk_queue_add_random(rq->q))
2465 add_disk_randomness(rq->rq_disk);
2467 return false;
2471 * blk_unprep_request - unprepare a request
2472 * @req: the request
2474 * This function makes a request ready for complete resubmission (or
2475 * completion). It happens only after all error handling is complete,
2476 * so represents the appropriate moment to deallocate any resources
2477 * that were allocated to the request in the prep_rq_fn. The queue
2478 * lock is held when calling this.
2480 void blk_unprep_request(struct request *req)
2482 struct request_queue *q = req->q;
2484 req->cmd_flags &= ~REQ_DONTPREP;
2485 if (q->unprep_rq_fn)
2486 q->unprep_rq_fn(q, req);
2488 EXPORT_SYMBOL_GPL(blk_unprep_request);
2491 * queue lock must be held
2493 static void blk_finish_request(struct request *req, int error)
2495 if (blk_rq_tagged(req))
2496 blk_queue_end_tag(req->q, req);
2498 BUG_ON(blk_queued_rq(req));
2500 if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
2501 laptop_io_completion(&req->q->backing_dev_info);
2503 blk_delete_timer(req);
2505 if (req->cmd_flags & REQ_DONTPREP)
2506 blk_unprep_request(req);
2508 blk_account_io_done(req);
2510 if (req->end_io)
2511 req->end_io(req, error);
2512 else {
2513 if (blk_bidi_rq(req))
2514 __blk_put_request(req->next_rq->q, req->next_rq);
2516 __blk_put_request(req->q, req);
2521 * blk_end_bidi_request - Complete a bidi request
2522 * @rq: the request to complete
2523 * @error: %0 for success, < %0 for error
2524 * @nr_bytes: number of bytes to complete @rq
2525 * @bidi_bytes: number of bytes to complete @rq->next_rq
2527 * Description:
2528 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
2529 * Drivers that supports bidi can safely call this member for any
2530 * type of request, bidi or uni. In the later case @bidi_bytes is
2531 * just ignored.
2533 * Return:
2534 * %false - we are done with this request
2535 * %true - still buffers pending for this request
2537 static bool blk_end_bidi_request(struct request *rq, int error,
2538 unsigned int nr_bytes, unsigned int bidi_bytes)
2540 struct request_queue *q = rq->q;
2541 unsigned long flags;
2543 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2544 return true;
2546 spin_lock_irqsave(q->queue_lock, flags);
2547 blk_finish_request(rq, error);
2548 spin_unlock_irqrestore(q->queue_lock, flags);
2550 return false;
2554 * __blk_end_bidi_request - Complete a bidi request with queue lock held
2555 * @rq: the request to complete
2556 * @error: %0 for success, < %0 for error
2557 * @nr_bytes: number of bytes to complete @rq
2558 * @bidi_bytes: number of bytes to complete @rq->next_rq
2560 * Description:
2561 * Identical to blk_end_bidi_request() except that queue lock is
2562 * assumed to be locked on entry and remains so on return.
2564 * Return:
2565 * %false - we are done with this request
2566 * %true - still buffers pending for this request
2568 bool __blk_end_bidi_request(struct request *rq, int error,
2569 unsigned int nr_bytes, unsigned int bidi_bytes)
2571 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
2572 return true;
2574 blk_finish_request(rq, error);
2576 return false;
2580 * blk_end_request - Helper function for drivers to complete the request.
2581 * @rq: the request being processed
2582 * @error: %0 for success, < %0 for error
2583 * @nr_bytes: number of bytes to complete
2585 * Description:
2586 * Ends I/O on a number of bytes attached to @rq.
2587 * If @rq has leftover, sets it up for the next range of segments.
2589 * Return:
2590 * %false - we are done with this request
2591 * %true - still buffers pending for this request
2593 bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2595 return blk_end_bidi_request(rq, error, nr_bytes, 0);
2597 EXPORT_SYMBOL(blk_end_request);
2600 * blk_end_request_all - Helper function for drives to finish the request.
2601 * @rq: the request to finish
2602 * @error: %0 for success, < %0 for error
2604 * Description:
2605 * Completely finish @rq.
2607 void blk_end_request_all(struct request *rq, int error)
2609 bool pending;
2610 unsigned int bidi_bytes = 0;
2612 if (unlikely(blk_bidi_rq(rq)))
2613 bidi_bytes = blk_rq_bytes(rq->next_rq);
2615 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2616 BUG_ON(pending);
2618 EXPORT_SYMBOL(blk_end_request_all);
2621 * blk_end_request_cur - Helper function to finish the current request chunk.
2622 * @rq: the request to finish the current chunk for
2623 * @error: %0 for success, < %0 for error
2625 * Description:
2626 * Complete the current consecutively mapped chunk from @rq.
2628 * Return:
2629 * %false - we are done with this request
2630 * %true - still buffers pending for this request
2632 bool blk_end_request_cur(struct request *rq, int error)
2634 return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2636 EXPORT_SYMBOL(blk_end_request_cur);
2639 * blk_end_request_err - Finish a request till the next failure boundary.
2640 * @rq: the request to finish till the next failure boundary for
2641 * @error: must be negative errno
2643 * Description:
2644 * Complete @rq till the next failure boundary.
2646 * Return:
2647 * %false - we are done with this request
2648 * %true - still buffers pending for this request
2650 bool blk_end_request_err(struct request *rq, int error)
2652 WARN_ON(error >= 0);
2653 return blk_end_request(rq, error, blk_rq_err_bytes(rq));
2655 EXPORT_SYMBOL_GPL(blk_end_request_err);
2658 * __blk_end_request - Helper function for drivers to complete the request.
2659 * @rq: the request being processed
2660 * @error: %0 for success, < %0 for error
2661 * @nr_bytes: number of bytes to complete
2663 * Description:
2664 * Must be called with queue lock held unlike blk_end_request().
2666 * Return:
2667 * %false - we are done with this request
2668 * %true - still buffers pending for this request
2670 bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
2672 return __blk_end_bidi_request(rq, error, nr_bytes, 0);
2674 EXPORT_SYMBOL(__blk_end_request);
2677 * __blk_end_request_all - Helper function for drives to finish the request.
2678 * @rq: the request to finish
2679 * @error: %0 for success, < %0 for error
2681 * Description:
2682 * Completely finish @rq. Must be called with queue lock held.
2684 void __blk_end_request_all(struct request *rq, int error)
2686 bool pending;
2687 unsigned int bidi_bytes = 0;
2689 if (unlikely(blk_bidi_rq(rq)))
2690 bidi_bytes = blk_rq_bytes(rq->next_rq);
2692 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
2693 BUG_ON(pending);
2695 EXPORT_SYMBOL(__blk_end_request_all);
2698 * __blk_end_request_cur - Helper function to finish the current request chunk.
2699 * @rq: the request to finish the current chunk for
2700 * @error: %0 for success, < %0 for error
2702 * Description:
2703 * Complete the current consecutively mapped chunk from @rq. Must
2704 * be called with queue lock held.
2706 * Return:
2707 * %false - we are done with this request
2708 * %true - still buffers pending for this request
2710 bool __blk_end_request_cur(struct request *rq, int error)
2712 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
2714 EXPORT_SYMBOL(__blk_end_request_cur);
2717 * __blk_end_request_err - Finish a request till the next failure boundary.
2718 * @rq: the request to finish till the next failure boundary for
2719 * @error: must be negative errno
2721 * Description:
2722 * Complete @rq till the next failure boundary. Must be called
2723 * with queue lock held.
2725 * Return:
2726 * %false - we are done with this request
2727 * %true - still buffers pending for this request
2729 bool __blk_end_request_err(struct request *rq, int error)
2731 WARN_ON(error >= 0);
2732 return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
2734 EXPORT_SYMBOL_GPL(__blk_end_request_err);
2736 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
2737 struct bio *bio)
2739 /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
2740 rq->cmd_flags |= bio->bi_rw & REQ_WRITE;
2742 if (bio_has_data(bio)) {
2743 rq->nr_phys_segments = bio_phys_segments(q, bio);
2744 rq->buffer = bio_data(bio);
2746 rq->__data_len = bio->bi_iter.bi_size;
2747 rq->bio = rq->biotail = bio;
2749 if (bio->bi_bdev)
2750 rq->rq_disk = bio->bi_bdev->bd_disk;
2753 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
2755 * rq_flush_dcache_pages - Helper function to flush all pages in a request
2756 * @rq: the request to be flushed
2758 * Description:
2759 * Flush all pages in @rq.
2761 void rq_flush_dcache_pages(struct request *rq)
2763 struct req_iterator iter;
2764 struct bio_vec bvec;
2766 rq_for_each_segment(bvec, rq, iter)
2767 flush_dcache_page(bvec.bv_page);
2769 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
2770 #endif
2773 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
2774 * @q : the queue of the device being checked
2776 * Description:
2777 * Check if underlying low-level drivers of a device are busy.
2778 * If the drivers want to export their busy state, they must set own
2779 * exporting function using blk_queue_lld_busy() first.
2781 * Basically, this function is used only by request stacking drivers
2782 * to stop dispatching requests to underlying devices when underlying
2783 * devices are busy. This behavior helps more I/O merging on the queue
2784 * of the request stacking driver and prevents I/O throughput regression
2785 * on burst I/O load.
2787 * Return:
2788 * 0 - Not busy (The request stacking driver should dispatch request)
2789 * 1 - Busy (The request stacking driver should stop dispatching request)
2791 int blk_lld_busy(struct request_queue *q)
2793 if (q->lld_busy_fn)
2794 return q->lld_busy_fn(q);
2796 return 0;
2798 EXPORT_SYMBOL_GPL(blk_lld_busy);
2801 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
2802 * @rq: the clone request to be cleaned up
2804 * Description:
2805 * Free all bios in @rq for a cloned request.
2807 void blk_rq_unprep_clone(struct request *rq)
2809 struct bio *bio;
2811 while ((bio = rq->bio) != NULL) {
2812 rq->bio = bio->bi_next;
2814 bio_put(bio);
2817 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
2820 * Copy attributes of the original request to the clone request.
2821 * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied.
2823 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
2825 dst->cpu = src->cpu;
2826 dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
2827 dst->cmd_type = src->cmd_type;
2828 dst->__sector = blk_rq_pos(src);
2829 dst->__data_len = blk_rq_bytes(src);
2830 dst->nr_phys_segments = src->nr_phys_segments;
2831 dst->ioprio = src->ioprio;
2832 dst->extra_len = src->extra_len;
2836 * blk_rq_prep_clone - Helper function to setup clone request
2837 * @rq: the request to be setup
2838 * @rq_src: original request to be cloned
2839 * @bs: bio_set that bios for clone are allocated from
2840 * @gfp_mask: memory allocation mask for bio
2841 * @bio_ctr: setup function to be called for each clone bio.
2842 * Returns %0 for success, non %0 for failure.
2843 * @data: private data to be passed to @bio_ctr
2845 * Description:
2846 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
2847 * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense)
2848 * are not copied, and copying such parts is the caller's responsibility.
2849 * Also, pages which the original bios are pointing to are not copied
2850 * and the cloned bios just point same pages.
2851 * So cloned bios must be completed before original bios, which means
2852 * the caller must complete @rq before @rq_src.
2854 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
2855 struct bio_set *bs, gfp_t gfp_mask,
2856 int (*bio_ctr)(struct bio *, struct bio *, void *),
2857 void *data)
2859 struct bio *bio, *bio_src;
2861 if (!bs)
2862 bs = fs_bio_set;
2864 blk_rq_init(NULL, rq);
2866 __rq_for_each_bio(bio_src, rq_src) {
2867 bio = bio_clone_bioset(bio_src, gfp_mask, bs);
2868 if (!bio)
2869 goto free_and_out;
2871 if (bio_ctr && bio_ctr(bio, bio_src, data))
2872 goto free_and_out;
2874 if (rq->bio) {
2875 rq->biotail->bi_next = bio;
2876 rq->biotail = bio;
2877 } else
2878 rq->bio = rq->biotail = bio;
2881 __blk_rq_prep_clone(rq, rq_src);
2883 return 0;
2885 free_and_out:
2886 if (bio)
2887 bio_put(bio);
2888 blk_rq_unprep_clone(rq);
2890 return -ENOMEM;
2892 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
2894 int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
2896 return queue_work(kblockd_workqueue, work);
2898 EXPORT_SYMBOL(kblockd_schedule_work);
2900 int kblockd_schedule_delayed_work(struct request_queue *q,
2901 struct delayed_work *dwork, unsigned long delay)
2903 return queue_delayed_work(kblockd_workqueue, dwork, delay);
2905 EXPORT_SYMBOL(kblockd_schedule_delayed_work);
2907 #define PLUG_MAGIC 0x91827364
2910 * blk_start_plug - initialize blk_plug and track it inside the task_struct
2911 * @plug: The &struct blk_plug that needs to be initialized
2913 * Description:
2914 * Tracking blk_plug inside the task_struct will help with auto-flushing the
2915 * pending I/O should the task end up blocking between blk_start_plug() and
2916 * blk_finish_plug(). This is important from a performance perspective, but
2917 * also ensures that we don't deadlock. For instance, if the task is blocking
2918 * for a memory allocation, memory reclaim could end up wanting to free a
2919 * page belonging to that request that is currently residing in our private
2920 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
2921 * this kind of deadlock.
2923 void blk_start_plug(struct blk_plug *plug)
2925 struct task_struct *tsk = current;
2927 plug->magic = PLUG_MAGIC;
2928 INIT_LIST_HEAD(&plug->list);
2929 INIT_LIST_HEAD(&plug->mq_list);
2930 INIT_LIST_HEAD(&plug->cb_list);
2933 * If this is a nested plug, don't actually assign it. It will be
2934 * flushed on its own.
2936 if (!tsk->plug) {
2938 * Store ordering should not be needed here, since a potential
2939 * preempt will imply a full memory barrier
2941 tsk->plug = plug;
2944 EXPORT_SYMBOL(blk_start_plug);
2946 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
2948 struct request *rqa = container_of(a, struct request, queuelist);
2949 struct request *rqb = container_of(b, struct request, queuelist);
2951 return !(rqa->q < rqb->q ||
2952 (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
2956 * If 'from_schedule' is true, then postpone the dispatch of requests
2957 * until a safe kblockd context. We due this to avoid accidental big
2958 * additional stack usage in driver dispatch, in places where the originally
2959 * plugger did not intend it.
2961 static void queue_unplugged(struct request_queue *q, unsigned int depth,
2962 bool from_schedule)
2963 __releases(q->queue_lock)
2965 trace_block_unplug(q, depth, !from_schedule);
2967 if (from_schedule)
2968 blk_run_queue_async(q);
2969 else
2970 __blk_run_queue(q);
2971 spin_unlock(q->queue_lock);
2974 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
2976 LIST_HEAD(callbacks);
2978 while (!list_empty(&plug->cb_list)) {
2979 list_splice_init(&plug->cb_list, &callbacks);
2981 while (!list_empty(&callbacks)) {
2982 struct blk_plug_cb *cb = list_first_entry(&callbacks,
2983 struct blk_plug_cb,
2984 list);
2985 list_del(&cb->list);
2986 cb->callback(cb, from_schedule);
2991 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
2992 int size)
2994 struct blk_plug *plug = current->plug;
2995 struct blk_plug_cb *cb;
2997 if (!plug)
2998 return NULL;
3000 list_for_each_entry(cb, &plug->cb_list, list)
3001 if (cb->callback == unplug && cb->data == data)
3002 return cb;
3004 /* Not currently on the callback list */
3005 BUG_ON(size < sizeof(*cb));
3006 cb = kzalloc(size, GFP_ATOMIC);
3007 if (cb) {
3008 cb->data = data;
3009 cb->callback = unplug;
3010 list_add(&cb->list, &plug->cb_list);
3012 return cb;
3014 EXPORT_SYMBOL(blk_check_plugged);
3016 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
3018 struct request_queue *q;
3019 unsigned long flags;
3020 struct request *rq;
3021 LIST_HEAD(list);
3022 unsigned int depth;
3024 BUG_ON(plug->magic != PLUG_MAGIC);
3026 flush_plug_callbacks(plug, from_schedule);
3028 if (!list_empty(&plug->mq_list))
3029 blk_mq_flush_plug_list(plug, from_schedule);
3031 if (list_empty(&plug->list))
3032 return;
3034 list_splice_init(&plug->list, &list);
3036 list_sort(NULL, &list, plug_rq_cmp);
3038 q = NULL;
3039 depth = 0;
3042 * Save and disable interrupts here, to avoid doing it for every
3043 * queue lock we have to take.
3045 local_irq_save(flags);
3046 while (!list_empty(&list)) {
3047 rq = list_entry_rq(list.next);
3048 list_del_init(&rq->queuelist);
3049 BUG_ON(!rq->q);
3050 if (rq->q != q) {
3052 * This drops the queue lock
3054 if (q)
3055 queue_unplugged(q, depth, from_schedule);
3056 q = rq->q;
3057 depth = 0;
3058 spin_lock(q->queue_lock);
3062 * Short-circuit if @q is dead
3064 if (unlikely(blk_queue_dying(q))) {
3065 __blk_end_request_all(rq, -ENODEV);
3066 continue;
3070 * rq is already accounted, so use raw insert
3072 if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA))
3073 __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
3074 else
3075 __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
3077 depth++;
3081 * This drops the queue lock
3083 if (q)
3084 queue_unplugged(q, depth, from_schedule);
3086 local_irq_restore(flags);
3089 void blk_finish_plug(struct blk_plug *plug)
3091 blk_flush_plug_list(plug, false);
3093 if (plug == current->plug)
3094 current->plug = NULL;
3096 EXPORT_SYMBOL(blk_finish_plug);
3098 #ifdef CONFIG_PM_RUNTIME
3100 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3101 * @q: the queue of the device
3102 * @dev: the device the queue belongs to
3104 * Description:
3105 * Initialize runtime-PM-related fields for @q and start auto suspend for
3106 * @dev. Drivers that want to take advantage of request-based runtime PM
3107 * should call this function after @dev has been initialized, and its
3108 * request queue @q has been allocated, and runtime PM for it can not happen
3109 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3110 * cases, driver should call this function before any I/O has taken place.
3112 * This function takes care of setting up using auto suspend for the device,
3113 * the autosuspend delay is set to -1 to make runtime suspend impossible
3114 * until an updated value is either set by user or by driver. Drivers do
3115 * not need to touch other autosuspend settings.
3117 * The block layer runtime PM is request based, so only works for drivers
3118 * that use request as their IO unit instead of those directly use bio's.
3120 void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
3122 q->dev = dev;
3123 q->rpm_status = RPM_ACTIVE;
3124 pm_runtime_set_autosuspend_delay(q->dev, -1);
3125 pm_runtime_use_autosuspend(q->dev);
3127 EXPORT_SYMBOL(blk_pm_runtime_init);
3130 * blk_pre_runtime_suspend - Pre runtime suspend check
3131 * @q: the queue of the device
3133 * Description:
3134 * This function will check if runtime suspend is allowed for the device
3135 * by examining if there are any requests pending in the queue. If there
3136 * are requests pending, the device can not be runtime suspended; otherwise,
3137 * the queue's status will be updated to SUSPENDING and the driver can
3138 * proceed to suspend the device.
3140 * For the not allowed case, we mark last busy for the device so that
3141 * runtime PM core will try to autosuspend it some time later.
3143 * This function should be called near the start of the device's
3144 * runtime_suspend callback.
3146 * Return:
3147 * 0 - OK to runtime suspend the device
3148 * -EBUSY - Device should not be runtime suspended
3150 int blk_pre_runtime_suspend(struct request_queue *q)
3152 int ret = 0;
3154 spin_lock_irq(q->queue_lock);
3155 if (q->nr_pending) {
3156 ret = -EBUSY;
3157 pm_runtime_mark_last_busy(q->dev);
3158 } else {
3159 q->rpm_status = RPM_SUSPENDING;
3161 spin_unlock_irq(q->queue_lock);
3162 return ret;
3164 EXPORT_SYMBOL(blk_pre_runtime_suspend);
3167 * blk_post_runtime_suspend - Post runtime suspend processing
3168 * @q: the queue of the device
3169 * @err: return value of the device's runtime_suspend function
3171 * Description:
3172 * Update the queue's runtime status according to the return value of the
3173 * device's runtime suspend function and mark last busy for the device so
3174 * that PM core will try to auto suspend the device at a later time.
3176 * This function should be called near the end of the device's
3177 * runtime_suspend callback.
3179 void blk_post_runtime_suspend(struct request_queue *q, int err)
3181 spin_lock_irq(q->queue_lock);
3182 if (!err) {
3183 q->rpm_status = RPM_SUSPENDED;
3184 } else {
3185 q->rpm_status = RPM_ACTIVE;
3186 pm_runtime_mark_last_busy(q->dev);
3188 spin_unlock_irq(q->queue_lock);
3190 EXPORT_SYMBOL(blk_post_runtime_suspend);
3193 * blk_pre_runtime_resume - Pre runtime resume processing
3194 * @q: the queue of the device
3196 * Description:
3197 * Update the queue's runtime status to RESUMING in preparation for the
3198 * runtime resume of the device.
3200 * This function should be called near the start of the device's
3201 * runtime_resume callback.
3203 void blk_pre_runtime_resume(struct request_queue *q)
3205 spin_lock_irq(q->queue_lock);
3206 q->rpm_status = RPM_RESUMING;
3207 spin_unlock_irq(q->queue_lock);
3209 EXPORT_SYMBOL(blk_pre_runtime_resume);
3212 * blk_post_runtime_resume - Post runtime resume processing
3213 * @q: the queue of the device
3214 * @err: return value of the device's runtime_resume function
3216 * Description:
3217 * Update the queue's runtime status according to the return value of the
3218 * device's runtime_resume function. If it is successfully resumed, process
3219 * the requests that are queued into the device's queue when it is resuming
3220 * and then mark last busy and initiate autosuspend for it.
3222 * This function should be called near the end of the device's
3223 * runtime_resume callback.
3225 void blk_post_runtime_resume(struct request_queue *q, int err)
3227 spin_lock_irq(q->queue_lock);
3228 if (!err) {
3229 q->rpm_status = RPM_ACTIVE;
3230 __blk_run_queue(q);
3231 pm_runtime_mark_last_busy(q->dev);
3232 pm_request_autosuspend(q->dev);
3233 } else {
3234 q->rpm_status = RPM_SUSPENDED;
3236 spin_unlock_irq(q->queue_lock);
3238 EXPORT_SYMBOL(blk_post_runtime_resume);
3239 #endif
3241 int __init blk_dev_init(void)
3243 BUILD_BUG_ON(__REQ_NR_BITS > 8 *
3244 sizeof(((struct request *)0)->cmd_flags));
3246 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3247 kblockd_workqueue = alloc_workqueue("kblockd",
3248 WQ_MEM_RECLAIM | WQ_HIGHPRI |
3249 WQ_POWER_EFFICIENT, 0);
3250 if (!kblockd_workqueue)
3251 panic("Failed to create kblockd\n");
3253 request_cachep = kmem_cache_create("blkdev_requests",
3254 sizeof(struct request), 0, SLAB_PANIC, NULL);
3256 blk_requestq_cachep = kmem_cache_create("blkdev_queue",
3257 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
3259 return 0;