ACPI / LPSS: Make acpi_lpss_find_device() also find PCI devices
[linux/fpc-iii.git] / block / blk-core.c
blob4dbc93f43b38231657ec2c97e836b5063a7265cf
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>
35 #include <linux/blk-cgroup.h>
36 #include <linux/debugfs.h>
37 #include <linux/bpf.h>
39 #define CREATE_TRACE_POINTS
40 #include <trace/events/block.h>
42 #include "blk.h"
43 #include "blk-mq.h"
44 #include "blk-mq-sched.h"
45 #include "blk-rq-qos.h"
47 #ifdef CONFIG_DEBUG_FS
48 struct dentry *blk_debugfs_root;
49 #endif
51 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
52 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
53 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
54 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
55 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
57 DEFINE_IDA(blk_queue_ida);
60 * For the allocated request tables
62 struct kmem_cache *request_cachep;
65 * For queue allocation
67 struct kmem_cache *blk_requestq_cachep;
70 * Controlling structure to kblockd
72 static struct workqueue_struct *kblockd_workqueue;
74 /**
75 * blk_queue_flag_set - atomically set a queue flag
76 * @flag: flag to be set
77 * @q: request queue
79 void blk_queue_flag_set(unsigned int flag, struct request_queue *q)
81 unsigned long flags;
83 spin_lock_irqsave(q->queue_lock, flags);
84 queue_flag_set(flag, q);
85 spin_unlock_irqrestore(q->queue_lock, flags);
87 EXPORT_SYMBOL(blk_queue_flag_set);
89 /**
90 * blk_queue_flag_clear - atomically clear a queue flag
91 * @flag: flag to be cleared
92 * @q: request queue
94 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
96 unsigned long flags;
98 spin_lock_irqsave(q->queue_lock, flags);
99 queue_flag_clear(flag, q);
100 spin_unlock_irqrestore(q->queue_lock, flags);
102 EXPORT_SYMBOL(blk_queue_flag_clear);
105 * blk_queue_flag_test_and_set - atomically test and set a queue flag
106 * @flag: flag to be set
107 * @q: request queue
109 * Returns the previous value of @flag - 0 if the flag was not set and 1 if
110 * the flag was already set.
112 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q)
114 unsigned long flags;
115 bool res;
117 spin_lock_irqsave(q->queue_lock, flags);
118 res = queue_flag_test_and_set(flag, q);
119 spin_unlock_irqrestore(q->queue_lock, flags);
121 return res;
123 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set);
126 * blk_queue_flag_test_and_clear - atomically test and clear a queue flag
127 * @flag: flag to be cleared
128 * @q: request queue
130 * Returns the previous value of @flag - 0 if the flag was not set and 1 if
131 * the flag was set.
133 bool blk_queue_flag_test_and_clear(unsigned int flag, struct request_queue *q)
135 unsigned long flags;
136 bool res;
138 spin_lock_irqsave(q->queue_lock, flags);
139 res = queue_flag_test_and_clear(flag, q);
140 spin_unlock_irqrestore(q->queue_lock, flags);
142 return res;
144 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_clear);
146 static void blk_clear_congested(struct request_list *rl, int sync)
148 #ifdef CONFIG_CGROUP_WRITEBACK
149 clear_wb_congested(rl->blkg->wb_congested, sync);
150 #else
152 * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't
153 * flip its congestion state for events on other blkcgs.
155 if (rl == &rl->q->root_rl)
156 clear_wb_congested(rl->q->backing_dev_info->wb.congested, sync);
157 #endif
160 static void blk_set_congested(struct request_list *rl, int sync)
162 #ifdef CONFIG_CGROUP_WRITEBACK
163 set_wb_congested(rl->blkg->wb_congested, sync);
164 #else
165 /* see blk_clear_congested() */
166 if (rl == &rl->q->root_rl)
167 set_wb_congested(rl->q->backing_dev_info->wb.congested, sync);
168 #endif
171 void blk_queue_congestion_threshold(struct request_queue *q)
173 int nr;
175 nr = q->nr_requests - (q->nr_requests / 8) + 1;
176 if (nr > q->nr_requests)
177 nr = q->nr_requests;
178 q->nr_congestion_on = nr;
180 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
181 if (nr < 1)
182 nr = 1;
183 q->nr_congestion_off = nr;
186 void blk_rq_init(struct request_queue *q, struct request *rq)
188 memset(rq, 0, sizeof(*rq));
190 INIT_LIST_HEAD(&rq->queuelist);
191 INIT_LIST_HEAD(&rq->timeout_list);
192 rq->cpu = -1;
193 rq->q = q;
194 rq->__sector = (sector_t) -1;
195 INIT_HLIST_NODE(&rq->hash);
196 RB_CLEAR_NODE(&rq->rb_node);
197 rq->tag = -1;
198 rq->internal_tag = -1;
199 rq->start_time_ns = ktime_get_ns();
200 rq->part = NULL;
202 EXPORT_SYMBOL(blk_rq_init);
204 static const struct {
205 int errno;
206 const char *name;
207 } blk_errors[] = {
208 [BLK_STS_OK] = { 0, "" },
209 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" },
210 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" },
211 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" },
212 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" },
213 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" },
214 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" },
215 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" },
216 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" },
217 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" },
218 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" },
219 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" },
221 /* device mapper special case, should not leak out: */
222 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" },
224 /* everything else not covered above: */
225 [BLK_STS_IOERR] = { -EIO, "I/O" },
228 blk_status_t errno_to_blk_status(int errno)
230 int i;
232 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) {
233 if (blk_errors[i].errno == errno)
234 return (__force blk_status_t)i;
237 return BLK_STS_IOERR;
239 EXPORT_SYMBOL_GPL(errno_to_blk_status);
241 int blk_status_to_errno(blk_status_t status)
243 int idx = (__force int)status;
245 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
246 return -EIO;
247 return blk_errors[idx].errno;
249 EXPORT_SYMBOL_GPL(blk_status_to_errno);
251 static void print_req_error(struct request *req, blk_status_t status)
253 int idx = (__force int)status;
255 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
256 return;
258 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
259 __func__, blk_errors[idx].name, req->rq_disk ?
260 req->rq_disk->disk_name : "?",
261 (unsigned long long)blk_rq_pos(req));
264 static void req_bio_endio(struct request *rq, struct bio *bio,
265 unsigned int nbytes, blk_status_t error)
267 if (error)
268 bio->bi_status = error;
270 if (unlikely(rq->rq_flags & RQF_QUIET))
271 bio_set_flag(bio, BIO_QUIET);
273 bio_advance(bio, nbytes);
275 /* don't actually finish bio if it's part of flush sequence */
276 if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
277 bio_endio(bio);
280 void blk_dump_rq_flags(struct request *rq, char *msg)
282 printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg,
283 rq->rq_disk ? rq->rq_disk->disk_name : "?",
284 (unsigned long long) rq->cmd_flags);
286 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
287 (unsigned long long)blk_rq_pos(rq),
288 blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
289 printk(KERN_INFO " bio %p, biotail %p, len %u\n",
290 rq->bio, rq->biotail, blk_rq_bytes(rq));
292 EXPORT_SYMBOL(blk_dump_rq_flags);
294 static void blk_delay_work(struct work_struct *work)
296 struct request_queue *q;
298 q = container_of(work, struct request_queue, delay_work.work);
299 spin_lock_irq(q->queue_lock);
300 __blk_run_queue(q);
301 spin_unlock_irq(q->queue_lock);
305 * blk_delay_queue - restart queueing after defined interval
306 * @q: The &struct request_queue in question
307 * @msecs: Delay in msecs
309 * Description:
310 * Sometimes queueing needs to be postponed for a little while, to allow
311 * resources to come back. This function will make sure that queueing is
312 * restarted around the specified time.
314 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
316 lockdep_assert_held(q->queue_lock);
317 WARN_ON_ONCE(q->mq_ops);
319 if (likely(!blk_queue_dead(q)))
320 queue_delayed_work(kblockd_workqueue, &q->delay_work,
321 msecs_to_jiffies(msecs));
323 EXPORT_SYMBOL(blk_delay_queue);
326 * blk_start_queue_async - asynchronously restart a previously stopped queue
327 * @q: The &struct request_queue in question
329 * Description:
330 * blk_start_queue_async() will clear the stop flag on the queue, and
331 * ensure that the request_fn for the queue is run from an async
332 * context.
334 void blk_start_queue_async(struct request_queue *q)
336 lockdep_assert_held(q->queue_lock);
337 WARN_ON_ONCE(q->mq_ops);
339 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
340 blk_run_queue_async(q);
342 EXPORT_SYMBOL(blk_start_queue_async);
345 * blk_start_queue - restart a previously stopped queue
346 * @q: The &struct request_queue in question
348 * Description:
349 * blk_start_queue() will clear the stop flag on the queue, and call
350 * the request_fn for the queue if it was in a stopped state when
351 * entered. Also see blk_stop_queue().
353 void blk_start_queue(struct request_queue *q)
355 lockdep_assert_held(q->queue_lock);
356 WARN_ON_ONCE(q->mq_ops);
358 queue_flag_clear(QUEUE_FLAG_STOPPED, q);
359 __blk_run_queue(q);
361 EXPORT_SYMBOL(blk_start_queue);
364 * blk_stop_queue - stop a queue
365 * @q: The &struct request_queue in question
367 * Description:
368 * The Linux block layer assumes that a block driver will consume all
369 * entries on the request queue when the request_fn strategy is called.
370 * Often this will not happen, because of hardware limitations (queue
371 * depth settings). If a device driver gets a 'queue full' response,
372 * or if it simply chooses not to queue more I/O at one point, it can
373 * call this function to prevent the request_fn from being called until
374 * the driver has signalled it's ready to go again. This happens by calling
375 * blk_start_queue() to restart queue operations.
377 void blk_stop_queue(struct request_queue *q)
379 lockdep_assert_held(q->queue_lock);
380 WARN_ON_ONCE(q->mq_ops);
382 cancel_delayed_work(&q->delay_work);
383 queue_flag_set(QUEUE_FLAG_STOPPED, q);
385 EXPORT_SYMBOL(blk_stop_queue);
388 * blk_sync_queue - cancel any pending callbacks on a queue
389 * @q: the queue
391 * Description:
392 * The block layer may perform asynchronous callback activity
393 * on a queue, such as calling the unplug function after a timeout.
394 * A block device may call blk_sync_queue to ensure that any
395 * such activity is cancelled, thus allowing it to release resources
396 * that the callbacks might use. The caller must already have made sure
397 * that its ->make_request_fn will not re-add plugging prior to calling
398 * this function.
400 * This function does not cancel any asynchronous activity arising
401 * out of elevator or throttling code. That would require elevator_exit()
402 * and blkcg_exit_queue() to be called with queue lock initialized.
405 void blk_sync_queue(struct request_queue *q)
407 del_timer_sync(&q->timeout);
408 cancel_work_sync(&q->timeout_work);
410 if (q->mq_ops) {
411 struct blk_mq_hw_ctx *hctx;
412 int i;
414 cancel_delayed_work_sync(&q->requeue_work);
415 queue_for_each_hw_ctx(q, hctx, i)
416 cancel_delayed_work_sync(&hctx->run_work);
417 } else {
418 cancel_delayed_work_sync(&q->delay_work);
421 EXPORT_SYMBOL(blk_sync_queue);
424 * blk_set_preempt_only - set QUEUE_FLAG_PREEMPT_ONLY
425 * @q: request queue pointer
427 * Returns the previous value of the PREEMPT_ONLY flag - 0 if the flag was not
428 * set and 1 if the flag was already set.
430 int blk_set_preempt_only(struct request_queue *q)
432 return blk_queue_flag_test_and_set(QUEUE_FLAG_PREEMPT_ONLY, q);
434 EXPORT_SYMBOL_GPL(blk_set_preempt_only);
436 void blk_clear_preempt_only(struct request_queue *q)
438 blk_queue_flag_clear(QUEUE_FLAG_PREEMPT_ONLY, q);
439 wake_up_all(&q->mq_freeze_wq);
441 EXPORT_SYMBOL_GPL(blk_clear_preempt_only);
444 * __blk_run_queue_uncond - run a queue whether or not it has been stopped
445 * @q: The queue to run
447 * Description:
448 * Invoke request handling on a queue if there are any pending requests.
449 * May be used to restart request handling after a request has completed.
450 * This variant runs the queue whether or not the queue has been
451 * stopped. Must be called with the queue lock held and interrupts
452 * disabled. See also @blk_run_queue.
454 inline void __blk_run_queue_uncond(struct request_queue *q)
456 lockdep_assert_held(q->queue_lock);
457 WARN_ON_ONCE(q->mq_ops);
459 if (unlikely(blk_queue_dead(q)))
460 return;
463 * Some request_fn implementations, e.g. scsi_request_fn(), unlock
464 * the queue lock internally. As a result multiple threads may be
465 * running such a request function concurrently. Keep track of the
466 * number of active request_fn invocations such that blk_drain_queue()
467 * can wait until all these request_fn calls have finished.
469 q->request_fn_active++;
470 q->request_fn(q);
471 q->request_fn_active--;
473 EXPORT_SYMBOL_GPL(__blk_run_queue_uncond);
476 * __blk_run_queue - run a single device queue
477 * @q: The queue to run
479 * Description:
480 * See @blk_run_queue.
482 void __blk_run_queue(struct request_queue *q)
484 lockdep_assert_held(q->queue_lock);
485 WARN_ON_ONCE(q->mq_ops);
487 if (unlikely(blk_queue_stopped(q)))
488 return;
490 __blk_run_queue_uncond(q);
492 EXPORT_SYMBOL(__blk_run_queue);
495 * blk_run_queue_async - run a single device queue in workqueue context
496 * @q: The queue to run
498 * Description:
499 * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
500 * of us.
502 * Note:
503 * Since it is not allowed to run q->delay_work after blk_cleanup_queue()
504 * has canceled q->delay_work, callers must hold the queue lock to avoid
505 * race conditions between blk_cleanup_queue() and blk_run_queue_async().
507 void blk_run_queue_async(struct request_queue *q)
509 lockdep_assert_held(q->queue_lock);
510 WARN_ON_ONCE(q->mq_ops);
512 if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
513 mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
515 EXPORT_SYMBOL(blk_run_queue_async);
518 * blk_run_queue - run a single device queue
519 * @q: The queue to run
521 * Description:
522 * Invoke request handling on this queue, if it has pending work to do.
523 * May be used to restart queueing when a request has completed.
525 void blk_run_queue(struct request_queue *q)
527 unsigned long flags;
529 WARN_ON_ONCE(q->mq_ops);
531 spin_lock_irqsave(q->queue_lock, flags);
532 __blk_run_queue(q);
533 spin_unlock_irqrestore(q->queue_lock, flags);
535 EXPORT_SYMBOL(blk_run_queue);
537 void blk_put_queue(struct request_queue *q)
539 kobject_put(&q->kobj);
541 EXPORT_SYMBOL(blk_put_queue);
544 * __blk_drain_queue - drain requests from request_queue
545 * @q: queue to drain
546 * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
548 * Drain requests from @q. If @drain_all is set, all requests are drained.
549 * If not, only ELVPRIV requests are drained. The caller is responsible
550 * for ensuring that no new requests which need to be drained are queued.
552 static void __blk_drain_queue(struct request_queue *q, bool drain_all)
553 __releases(q->queue_lock)
554 __acquires(q->queue_lock)
556 int i;
558 lockdep_assert_held(q->queue_lock);
559 WARN_ON_ONCE(q->mq_ops);
561 while (true) {
562 bool drain = false;
565 * The caller might be trying to drain @q before its
566 * elevator is initialized.
568 if (q->elevator)
569 elv_drain_elevator(q);
571 blkcg_drain_queue(q);
574 * This function might be called on a queue which failed
575 * driver init after queue creation or is not yet fully
576 * active yet. Some drivers (e.g. fd and loop) get unhappy
577 * in such cases. Kick queue iff dispatch queue has
578 * something on it and @q has request_fn set.
580 if (!list_empty(&q->queue_head) && q->request_fn)
581 __blk_run_queue(q);
583 drain |= q->nr_rqs_elvpriv;
584 drain |= q->request_fn_active;
587 * Unfortunately, requests are queued at and tracked from
588 * multiple places and there's no single counter which can
589 * be drained. Check all the queues and counters.
591 if (drain_all) {
592 struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
593 drain |= !list_empty(&q->queue_head);
594 for (i = 0; i < 2; i++) {
595 drain |= q->nr_rqs[i];
596 drain |= q->in_flight[i];
597 if (fq)
598 drain |= !list_empty(&fq->flush_queue[i]);
602 if (!drain)
603 break;
605 spin_unlock_irq(q->queue_lock);
607 msleep(10);
609 spin_lock_irq(q->queue_lock);
613 * With queue marked dead, any woken up waiter will fail the
614 * allocation path, so the wakeup chaining is lost and we're
615 * left with hung waiters. We need to wake up those waiters.
617 if (q->request_fn) {
618 struct request_list *rl;
620 blk_queue_for_each_rl(rl, q)
621 for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
622 wake_up_all(&rl->wait[i]);
626 void blk_drain_queue(struct request_queue *q)
628 spin_lock_irq(q->queue_lock);
629 __blk_drain_queue(q, true);
630 spin_unlock_irq(q->queue_lock);
634 * blk_queue_bypass_start - enter queue bypass mode
635 * @q: queue of interest
637 * In bypass mode, only the dispatch FIFO queue of @q is used. This
638 * function makes @q enter bypass mode and drains all requests which were
639 * throttled or issued before. On return, it's guaranteed that no request
640 * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
641 * inside queue or RCU read lock.
643 void blk_queue_bypass_start(struct request_queue *q)
645 WARN_ON_ONCE(q->mq_ops);
647 spin_lock_irq(q->queue_lock);
648 q->bypass_depth++;
649 queue_flag_set(QUEUE_FLAG_BYPASS, q);
650 spin_unlock_irq(q->queue_lock);
653 * Queues start drained. Skip actual draining till init is
654 * complete. This avoids lenghty delays during queue init which
655 * can happen many times during boot.
657 if (blk_queue_init_done(q)) {
658 spin_lock_irq(q->queue_lock);
659 __blk_drain_queue(q, false);
660 spin_unlock_irq(q->queue_lock);
662 /* ensure blk_queue_bypass() is %true inside RCU read lock */
663 synchronize_rcu();
666 EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
669 * blk_queue_bypass_end - leave queue bypass mode
670 * @q: queue of interest
672 * Leave bypass mode and restore the normal queueing behavior.
674 * Note: although blk_queue_bypass_start() is only called for blk-sq queues,
675 * this function is called for both blk-sq and blk-mq queues.
677 void blk_queue_bypass_end(struct request_queue *q)
679 spin_lock_irq(q->queue_lock);
680 if (!--q->bypass_depth)
681 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
682 WARN_ON_ONCE(q->bypass_depth < 0);
683 spin_unlock_irq(q->queue_lock);
685 EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
687 void blk_set_queue_dying(struct request_queue *q)
689 blk_queue_flag_set(QUEUE_FLAG_DYING, q);
692 * When queue DYING flag is set, we need to block new req
693 * entering queue, so we call blk_freeze_queue_start() to
694 * prevent I/O from crossing blk_queue_enter().
696 blk_freeze_queue_start(q);
698 if (q->mq_ops)
699 blk_mq_wake_waiters(q);
700 else {
701 struct request_list *rl;
703 spin_lock_irq(q->queue_lock);
704 blk_queue_for_each_rl(rl, q) {
705 if (rl->rq_pool) {
706 wake_up_all(&rl->wait[BLK_RW_SYNC]);
707 wake_up_all(&rl->wait[BLK_RW_ASYNC]);
710 spin_unlock_irq(q->queue_lock);
713 /* Make blk_queue_enter() reexamine the DYING flag. */
714 wake_up_all(&q->mq_freeze_wq);
716 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
718 /* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */
719 void blk_exit_queue(struct request_queue *q)
722 * Since the I/O scheduler exit code may access cgroup information,
723 * perform I/O scheduler exit before disassociating from the block
724 * cgroup controller.
726 if (q->elevator) {
727 ioc_clear_queue(q);
728 elevator_exit(q, q->elevator);
729 q->elevator = NULL;
733 * Remove all references to @q from the block cgroup controller before
734 * restoring @q->queue_lock to avoid that restoring this pointer causes
735 * e.g. blkcg_print_blkgs() to crash.
737 blkcg_exit_queue(q);
740 * Since the cgroup code may dereference the @q->backing_dev_info
741 * pointer, only decrease its reference count after having removed the
742 * association with the block cgroup controller.
744 bdi_put(q->backing_dev_info);
748 * blk_cleanup_queue - shutdown a request queue
749 * @q: request queue to shutdown
751 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
752 * put it. All future requests will be failed immediately with -ENODEV.
754 void blk_cleanup_queue(struct request_queue *q)
756 spinlock_t *lock = q->queue_lock;
758 /* mark @q DYING, no new request or merges will be allowed afterwards */
759 mutex_lock(&q->sysfs_lock);
760 blk_set_queue_dying(q);
761 spin_lock_irq(lock);
764 * A dying queue is permanently in bypass mode till released. Note
765 * that, unlike blk_queue_bypass_start(), we aren't performing
766 * synchronize_rcu() after entering bypass mode to avoid the delay
767 * as some drivers create and destroy a lot of queues while
768 * probing. This is still safe because blk_release_queue() will be
769 * called only after the queue refcnt drops to zero and nothing,
770 * RCU or not, would be traversing the queue by then.
772 q->bypass_depth++;
773 queue_flag_set(QUEUE_FLAG_BYPASS, q);
775 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
776 queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
777 queue_flag_set(QUEUE_FLAG_DYING, q);
778 spin_unlock_irq(lock);
779 mutex_unlock(&q->sysfs_lock);
782 * Drain all requests queued before DYING marking. Set DEAD flag to
783 * prevent that q->request_fn() gets invoked after draining finished.
785 blk_freeze_queue(q);
786 spin_lock_irq(lock);
787 queue_flag_set(QUEUE_FLAG_DEAD, q);
788 spin_unlock_irq(lock);
791 * make sure all in-progress dispatch are completed because
792 * blk_freeze_queue() can only complete all requests, and
793 * dispatch may still be in-progress since we dispatch requests
794 * from more than one contexts.
796 * No need to quiesce queue if it isn't initialized yet since
797 * blk_freeze_queue() should be enough for cases of passthrough
798 * request.
800 if (q->mq_ops && blk_queue_init_done(q))
801 blk_mq_quiesce_queue(q);
803 /* for synchronous bio-based driver finish in-flight integrity i/o */
804 blk_flush_integrity();
806 /* @q won't process any more request, flush async actions */
807 del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer);
808 blk_sync_queue(q);
811 * I/O scheduler exit is only safe after the sysfs scheduler attribute
812 * has been removed.
814 WARN_ON_ONCE(q->kobj.state_in_sysfs);
816 blk_exit_queue(q);
818 if (q->mq_ops)
819 blk_mq_free_queue(q);
820 percpu_ref_exit(&q->q_usage_counter);
822 spin_lock_irq(lock);
823 if (q->queue_lock != &q->__queue_lock)
824 q->queue_lock = &q->__queue_lock;
825 spin_unlock_irq(lock);
827 /* @q is and will stay empty, shutdown and put */
828 blk_put_queue(q);
830 EXPORT_SYMBOL(blk_cleanup_queue);
832 /* Allocate memory local to the request queue */
833 static void *alloc_request_simple(gfp_t gfp_mask, void *data)
835 struct request_queue *q = data;
837 return kmem_cache_alloc_node(request_cachep, gfp_mask, q->node);
840 static void free_request_simple(void *element, void *data)
842 kmem_cache_free(request_cachep, element);
845 static void *alloc_request_size(gfp_t gfp_mask, void *data)
847 struct request_queue *q = data;
848 struct request *rq;
850 rq = kmalloc_node(sizeof(struct request) + q->cmd_size, gfp_mask,
851 q->node);
852 if (rq && q->init_rq_fn && q->init_rq_fn(q, rq, gfp_mask) < 0) {
853 kfree(rq);
854 rq = NULL;
856 return rq;
859 static void free_request_size(void *element, void *data)
861 struct request_queue *q = data;
863 if (q->exit_rq_fn)
864 q->exit_rq_fn(q, element);
865 kfree(element);
868 int blk_init_rl(struct request_list *rl, struct request_queue *q,
869 gfp_t gfp_mask)
871 if (unlikely(rl->rq_pool) || q->mq_ops)
872 return 0;
874 rl->q = q;
875 rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
876 rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
877 init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
878 init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
880 if (q->cmd_size) {
881 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ,
882 alloc_request_size, free_request_size,
883 q, gfp_mask, q->node);
884 } else {
885 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ,
886 alloc_request_simple, free_request_simple,
887 q, gfp_mask, q->node);
889 if (!rl->rq_pool)
890 return -ENOMEM;
892 if (rl != &q->root_rl)
893 WARN_ON_ONCE(!blk_get_queue(q));
895 return 0;
898 void blk_exit_rl(struct request_queue *q, struct request_list *rl)
900 if (rl->rq_pool) {
901 mempool_destroy(rl->rq_pool);
902 if (rl != &q->root_rl)
903 blk_put_queue(q);
907 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
909 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE, NULL);
911 EXPORT_SYMBOL(blk_alloc_queue);
914 * blk_queue_enter() - try to increase q->q_usage_counter
915 * @q: request queue pointer
916 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT
918 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
920 const bool preempt = flags & BLK_MQ_REQ_PREEMPT;
922 while (true) {
923 bool success = false;
925 rcu_read_lock();
926 if (percpu_ref_tryget_live(&q->q_usage_counter)) {
928 * The code that sets the PREEMPT_ONLY flag is
929 * responsible for ensuring that that flag is globally
930 * visible before the queue is unfrozen.
932 if (preempt || !blk_queue_preempt_only(q)) {
933 success = true;
934 } else {
935 percpu_ref_put(&q->q_usage_counter);
938 rcu_read_unlock();
940 if (success)
941 return 0;
943 if (flags & BLK_MQ_REQ_NOWAIT)
944 return -EBUSY;
947 * read pair of barrier in blk_freeze_queue_start(),
948 * we need to order reading __PERCPU_REF_DEAD flag of
949 * .q_usage_counter and reading .mq_freeze_depth or
950 * queue dying flag, otherwise the following wait may
951 * never return if the two reads are reordered.
953 smp_rmb();
955 wait_event(q->mq_freeze_wq,
956 (atomic_read(&q->mq_freeze_depth) == 0 &&
957 (preempt || !blk_queue_preempt_only(q))) ||
958 blk_queue_dying(q));
959 if (blk_queue_dying(q))
960 return -ENODEV;
964 void blk_queue_exit(struct request_queue *q)
966 percpu_ref_put(&q->q_usage_counter);
969 static void blk_queue_usage_counter_release(struct percpu_ref *ref)
971 struct request_queue *q =
972 container_of(ref, struct request_queue, q_usage_counter);
974 wake_up_all(&q->mq_freeze_wq);
977 static void blk_rq_timed_out_timer(struct timer_list *t)
979 struct request_queue *q = from_timer(q, t, timeout);
981 kblockd_schedule_work(&q->timeout_work);
985 * blk_alloc_queue_node - allocate a request queue
986 * @gfp_mask: memory allocation flags
987 * @node_id: NUMA node to allocate memory from
988 * @lock: For legacy queues, pointer to a spinlock that will be used to e.g.
989 * serialize calls to the legacy .request_fn() callback. Ignored for
990 * blk-mq request queues.
992 * Note: pass the queue lock as the third argument to this function instead of
993 * setting the queue lock pointer explicitly to avoid triggering a sporadic
994 * crash in the blkcg code. This function namely calls blkcg_init_queue() and
995 * the queue lock pointer must be set before blkcg_init_queue() is called.
997 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id,
998 spinlock_t *lock)
1000 struct request_queue *q;
1001 int ret;
1003 q = kmem_cache_alloc_node(blk_requestq_cachep,
1004 gfp_mask | __GFP_ZERO, node_id);
1005 if (!q)
1006 return NULL;
1008 INIT_LIST_HEAD(&q->queue_head);
1009 q->last_merge = NULL;
1010 q->end_sector = 0;
1011 q->boundary_rq = NULL;
1013 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
1014 if (q->id < 0)
1015 goto fail_q;
1017 ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
1018 if (ret)
1019 goto fail_id;
1021 q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id);
1022 if (!q->backing_dev_info)
1023 goto fail_split;
1025 q->stats = blk_alloc_queue_stats();
1026 if (!q->stats)
1027 goto fail_stats;
1029 q->backing_dev_info->ra_pages =
1030 (VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
1031 q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;
1032 q->backing_dev_info->name = "block";
1033 q->node = node_id;
1035 timer_setup(&q->backing_dev_info->laptop_mode_wb_timer,
1036 laptop_mode_timer_fn, 0);
1037 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
1038 INIT_WORK(&q->timeout_work, NULL);
1039 INIT_LIST_HEAD(&q->timeout_list);
1040 INIT_LIST_HEAD(&q->icq_list);
1041 #ifdef CONFIG_BLK_CGROUP
1042 INIT_LIST_HEAD(&q->blkg_list);
1043 #endif
1044 INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
1046 kobject_init(&q->kobj, &blk_queue_ktype);
1048 #ifdef CONFIG_BLK_DEV_IO_TRACE
1049 mutex_init(&q->blk_trace_mutex);
1050 #endif
1051 mutex_init(&q->sysfs_lock);
1052 spin_lock_init(&q->__queue_lock);
1054 if (!q->mq_ops)
1055 q->queue_lock = lock ? : &q->__queue_lock;
1058 * A queue starts its life with bypass turned on to avoid
1059 * unnecessary bypass on/off overhead and nasty surprises during
1060 * init. The initial bypass will be finished when the queue is
1061 * registered by blk_register_queue().
1063 q->bypass_depth = 1;
1064 queue_flag_set_unlocked(QUEUE_FLAG_BYPASS, q);
1066 init_waitqueue_head(&q->mq_freeze_wq);
1069 * Init percpu_ref in atomic mode so that it's faster to shutdown.
1070 * See blk_register_queue() for details.
1072 if (percpu_ref_init(&q->q_usage_counter,
1073 blk_queue_usage_counter_release,
1074 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
1075 goto fail_bdi;
1077 if (blkcg_init_queue(q))
1078 goto fail_ref;
1080 return q;
1082 fail_ref:
1083 percpu_ref_exit(&q->q_usage_counter);
1084 fail_bdi:
1085 blk_free_queue_stats(q->stats);
1086 fail_stats:
1087 bdi_put(q->backing_dev_info);
1088 fail_split:
1089 bioset_exit(&q->bio_split);
1090 fail_id:
1091 ida_simple_remove(&blk_queue_ida, q->id);
1092 fail_q:
1093 kmem_cache_free(blk_requestq_cachep, q);
1094 return NULL;
1096 EXPORT_SYMBOL(blk_alloc_queue_node);
1099 * blk_init_queue - prepare a request queue for use with a block device
1100 * @rfn: The function to be called to process requests that have been
1101 * placed on the queue.
1102 * @lock: Request queue spin lock
1104 * Description:
1105 * If a block device wishes to use the standard request handling procedures,
1106 * which sorts requests and coalesces adjacent requests, then it must
1107 * call blk_init_queue(). The function @rfn will be called when there
1108 * are requests on the queue that need to be processed. If the device
1109 * supports plugging, then @rfn may not be called immediately when requests
1110 * are available on the queue, but may be called at some time later instead.
1111 * Plugged queues are generally unplugged when a buffer belonging to one
1112 * of the requests on the queue is needed, or due to memory pressure.
1114 * @rfn is not required, or even expected, to remove all requests off the
1115 * queue, but only as many as it can handle at a time. If it does leave
1116 * requests on the queue, it is responsible for arranging that the requests
1117 * get dealt with eventually.
1119 * The queue spin lock must be held while manipulating the requests on the
1120 * request queue; this lock will be taken also from interrupt context, so irq
1121 * disabling is needed for it.
1123 * Function returns a pointer to the initialized request queue, or %NULL if
1124 * it didn't succeed.
1126 * Note:
1127 * blk_init_queue() must be paired with a blk_cleanup_queue() call
1128 * when the block device is deactivated (such as at module unload).
1131 struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
1133 return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
1135 EXPORT_SYMBOL(blk_init_queue);
1137 struct request_queue *
1138 blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
1140 struct request_queue *q;
1142 q = blk_alloc_queue_node(GFP_KERNEL, node_id, lock);
1143 if (!q)
1144 return NULL;
1146 q->request_fn = rfn;
1147 if (blk_init_allocated_queue(q) < 0) {
1148 blk_cleanup_queue(q);
1149 return NULL;
1152 return q;
1154 EXPORT_SYMBOL(blk_init_queue_node);
1156 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio);
1159 int blk_init_allocated_queue(struct request_queue *q)
1161 WARN_ON_ONCE(q->mq_ops);
1163 q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size);
1164 if (!q->fq)
1165 return -ENOMEM;
1167 if (q->init_rq_fn && q->init_rq_fn(q, q->fq->flush_rq, GFP_KERNEL))
1168 goto out_free_flush_queue;
1170 if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
1171 goto out_exit_flush_rq;
1173 INIT_WORK(&q->timeout_work, blk_timeout_work);
1174 q->queue_flags |= QUEUE_FLAG_DEFAULT;
1177 * This also sets hw/phys segments, boundary and size
1179 blk_queue_make_request(q, blk_queue_bio);
1181 q->sg_reserved_size = INT_MAX;
1183 if (elevator_init(q))
1184 goto out_exit_flush_rq;
1185 return 0;
1187 out_exit_flush_rq:
1188 if (q->exit_rq_fn)
1189 q->exit_rq_fn(q, q->fq->flush_rq);
1190 out_free_flush_queue:
1191 blk_free_flush_queue(q->fq);
1192 q->fq = NULL;
1193 return -ENOMEM;
1195 EXPORT_SYMBOL(blk_init_allocated_queue);
1197 bool blk_get_queue(struct request_queue *q)
1199 if (likely(!blk_queue_dying(q))) {
1200 __blk_get_queue(q);
1201 return true;
1204 return false;
1206 EXPORT_SYMBOL(blk_get_queue);
1208 static inline void blk_free_request(struct request_list *rl, struct request *rq)
1210 if (rq->rq_flags & RQF_ELVPRIV) {
1211 elv_put_request(rl->q, rq);
1212 if (rq->elv.icq)
1213 put_io_context(rq->elv.icq->ioc);
1216 mempool_free(rq, rl->rq_pool);
1220 * ioc_batching returns true if the ioc is a valid batching request and
1221 * should be given priority access to a request.
1223 static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
1225 if (!ioc)
1226 return 0;
1229 * Make sure the process is able to allocate at least 1 request
1230 * even if the batch times out, otherwise we could theoretically
1231 * lose wakeups.
1233 return ioc->nr_batch_requests == q->nr_batching ||
1234 (ioc->nr_batch_requests > 0
1235 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
1239 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
1240 * will cause the process to be a "batcher" on all queues in the system. This
1241 * is the behaviour we want though - once it gets a wakeup it should be given
1242 * a nice run.
1244 static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
1246 if (!ioc || ioc_batching(q, ioc))
1247 return;
1249 ioc->nr_batch_requests = q->nr_batching;
1250 ioc->last_waited = jiffies;
1253 static void __freed_request(struct request_list *rl, int sync)
1255 struct request_queue *q = rl->q;
1257 if (rl->count[sync] < queue_congestion_off_threshold(q))
1258 blk_clear_congested(rl, sync);
1260 if (rl->count[sync] + 1 <= q->nr_requests) {
1261 if (waitqueue_active(&rl->wait[sync]))
1262 wake_up(&rl->wait[sync]);
1264 blk_clear_rl_full(rl, sync);
1269 * A request has just been released. Account for it, update the full and
1270 * congestion status, wake up any waiters. Called under q->queue_lock.
1272 static void freed_request(struct request_list *rl, bool sync,
1273 req_flags_t rq_flags)
1275 struct request_queue *q = rl->q;
1277 q->nr_rqs[sync]--;
1278 rl->count[sync]--;
1279 if (rq_flags & RQF_ELVPRIV)
1280 q->nr_rqs_elvpriv--;
1282 __freed_request(rl, sync);
1284 if (unlikely(rl->starved[sync ^ 1]))
1285 __freed_request(rl, sync ^ 1);
1288 int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
1290 struct request_list *rl;
1291 int on_thresh, off_thresh;
1293 WARN_ON_ONCE(q->mq_ops);
1295 spin_lock_irq(q->queue_lock);
1296 q->nr_requests = nr;
1297 blk_queue_congestion_threshold(q);
1298 on_thresh = queue_congestion_on_threshold(q);
1299 off_thresh = queue_congestion_off_threshold(q);
1301 blk_queue_for_each_rl(rl, q) {
1302 if (rl->count[BLK_RW_SYNC] >= on_thresh)
1303 blk_set_congested(rl, BLK_RW_SYNC);
1304 else if (rl->count[BLK_RW_SYNC] < off_thresh)
1305 blk_clear_congested(rl, BLK_RW_SYNC);
1307 if (rl->count[BLK_RW_ASYNC] >= on_thresh)
1308 blk_set_congested(rl, BLK_RW_ASYNC);
1309 else if (rl->count[BLK_RW_ASYNC] < off_thresh)
1310 blk_clear_congested(rl, BLK_RW_ASYNC);
1312 if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
1313 blk_set_rl_full(rl, BLK_RW_SYNC);
1314 } else {
1315 blk_clear_rl_full(rl, BLK_RW_SYNC);
1316 wake_up(&rl->wait[BLK_RW_SYNC]);
1319 if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
1320 blk_set_rl_full(rl, BLK_RW_ASYNC);
1321 } else {
1322 blk_clear_rl_full(rl, BLK_RW_ASYNC);
1323 wake_up(&rl->wait[BLK_RW_ASYNC]);
1327 spin_unlock_irq(q->queue_lock);
1328 return 0;
1332 * __get_request - get a free request
1333 * @rl: request list to allocate from
1334 * @op: operation and flags
1335 * @bio: bio to allocate request for (can be %NULL)
1336 * @flags: BLQ_MQ_REQ_* flags
1337 * @gfp_mask: allocator flags
1339 * Get a free request from @q. This function may fail under memory
1340 * pressure or if @q is dead.
1342 * Must be called with @q->queue_lock held and,
1343 * Returns ERR_PTR on failure, with @q->queue_lock held.
1344 * Returns request pointer on success, with @q->queue_lock *not held*.
1346 static struct request *__get_request(struct request_list *rl, unsigned int op,
1347 struct bio *bio, blk_mq_req_flags_t flags, gfp_t gfp_mask)
1349 struct request_queue *q = rl->q;
1350 struct request *rq;
1351 struct elevator_type *et = q->elevator->type;
1352 struct io_context *ioc = rq_ioc(bio);
1353 struct io_cq *icq = NULL;
1354 const bool is_sync = op_is_sync(op);
1355 int may_queue;
1356 req_flags_t rq_flags = RQF_ALLOCED;
1358 lockdep_assert_held(q->queue_lock);
1360 if (unlikely(blk_queue_dying(q)))
1361 return ERR_PTR(-ENODEV);
1363 may_queue = elv_may_queue(q, op);
1364 if (may_queue == ELV_MQUEUE_NO)
1365 goto rq_starved;
1367 if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
1368 if (rl->count[is_sync]+1 >= q->nr_requests) {
1370 * The queue will fill after this allocation, so set
1371 * it as full, and mark this process as "batching".
1372 * This process will be allowed to complete a batch of
1373 * requests, others will be blocked.
1375 if (!blk_rl_full(rl, is_sync)) {
1376 ioc_set_batching(q, ioc);
1377 blk_set_rl_full(rl, is_sync);
1378 } else {
1379 if (may_queue != ELV_MQUEUE_MUST
1380 && !ioc_batching(q, ioc)) {
1382 * The queue is full and the allocating
1383 * process is not a "batcher", and not
1384 * exempted by the IO scheduler
1386 return ERR_PTR(-ENOMEM);
1390 blk_set_congested(rl, is_sync);
1394 * Only allow batching queuers to allocate up to 50% over the defined
1395 * limit of requests, otherwise we could have thousands of requests
1396 * allocated with any setting of ->nr_requests
1398 if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
1399 return ERR_PTR(-ENOMEM);
1401 q->nr_rqs[is_sync]++;
1402 rl->count[is_sync]++;
1403 rl->starved[is_sync] = 0;
1406 * Decide whether the new request will be managed by elevator. If
1407 * so, mark @rq_flags and increment elvpriv. Non-zero elvpriv will
1408 * prevent the current elevator from being destroyed until the new
1409 * request is freed. This guarantees icq's won't be destroyed and
1410 * makes creating new ones safe.
1412 * Flush requests do not use the elevator so skip initialization.
1413 * This allows a request to share the flush and elevator data.
1415 * Also, lookup icq while holding queue_lock. If it doesn't exist,
1416 * it will be created after releasing queue_lock.
1418 if (!op_is_flush(op) && !blk_queue_bypass(q)) {
1419 rq_flags |= RQF_ELVPRIV;
1420 q->nr_rqs_elvpriv++;
1421 if (et->icq_cache && ioc)
1422 icq = ioc_lookup_icq(ioc, q);
1425 if (blk_queue_io_stat(q))
1426 rq_flags |= RQF_IO_STAT;
1427 spin_unlock_irq(q->queue_lock);
1429 /* allocate and init request */
1430 rq = mempool_alloc(rl->rq_pool, gfp_mask);
1431 if (!rq)
1432 goto fail_alloc;
1434 blk_rq_init(q, rq);
1435 blk_rq_set_rl(rq, rl);
1436 rq->cmd_flags = op;
1437 rq->rq_flags = rq_flags;
1438 if (flags & BLK_MQ_REQ_PREEMPT)
1439 rq->rq_flags |= RQF_PREEMPT;
1441 /* init elvpriv */
1442 if (rq_flags & RQF_ELVPRIV) {
1443 if (unlikely(et->icq_cache && !icq)) {
1444 if (ioc)
1445 icq = ioc_create_icq(ioc, q, gfp_mask);
1446 if (!icq)
1447 goto fail_elvpriv;
1450 rq->elv.icq = icq;
1451 if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
1452 goto fail_elvpriv;
1454 /* @rq->elv.icq holds io_context until @rq is freed */
1455 if (icq)
1456 get_io_context(icq->ioc);
1458 out:
1460 * ioc may be NULL here, and ioc_batching will be false. That's
1461 * OK, if the queue is under the request limit then requests need
1462 * not count toward the nr_batch_requests limit. There will always
1463 * be some limit enforced by BLK_BATCH_TIME.
1465 if (ioc_batching(q, ioc))
1466 ioc->nr_batch_requests--;
1468 trace_block_getrq(q, bio, op);
1469 return rq;
1471 fail_elvpriv:
1473 * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
1474 * and may fail indefinitely under memory pressure and thus
1475 * shouldn't stall IO. Treat this request as !elvpriv. This will
1476 * disturb iosched and blkcg but weird is bettern than dead.
1478 printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
1479 __func__, dev_name(q->backing_dev_info->dev));
1481 rq->rq_flags &= ~RQF_ELVPRIV;
1482 rq->elv.icq = NULL;
1484 spin_lock_irq(q->queue_lock);
1485 q->nr_rqs_elvpriv--;
1486 spin_unlock_irq(q->queue_lock);
1487 goto out;
1489 fail_alloc:
1491 * Allocation failed presumably due to memory. Undo anything we
1492 * might have messed up.
1494 * Allocating task should really be put onto the front of the wait
1495 * queue, but this is pretty rare.
1497 spin_lock_irq(q->queue_lock);
1498 freed_request(rl, is_sync, rq_flags);
1501 * in the very unlikely event that allocation failed and no
1502 * requests for this direction was pending, mark us starved so that
1503 * freeing of a request in the other direction will notice
1504 * us. another possible fix would be to split the rq mempool into
1505 * READ and WRITE
1507 rq_starved:
1508 if (unlikely(rl->count[is_sync] == 0))
1509 rl->starved[is_sync] = 1;
1510 return ERR_PTR(-ENOMEM);
1514 * get_request - get a free request
1515 * @q: request_queue to allocate request from
1516 * @op: operation and flags
1517 * @bio: bio to allocate request for (can be %NULL)
1518 * @flags: BLK_MQ_REQ_* flags.
1519 * @gfp: allocator flags
1521 * Get a free request from @q. If %BLK_MQ_REQ_NOWAIT is set in @flags,
1522 * this function keeps retrying under memory pressure and fails iff @q is dead.
1524 * Must be called with @q->queue_lock held and,
1525 * Returns ERR_PTR on failure, with @q->queue_lock held.
1526 * Returns request pointer on success, with @q->queue_lock *not held*.
1528 static struct request *get_request(struct request_queue *q, unsigned int op,
1529 struct bio *bio, blk_mq_req_flags_t flags, gfp_t gfp)
1531 const bool is_sync = op_is_sync(op);
1532 DEFINE_WAIT(wait);
1533 struct request_list *rl;
1534 struct request *rq;
1536 lockdep_assert_held(q->queue_lock);
1537 WARN_ON_ONCE(q->mq_ops);
1539 rl = blk_get_rl(q, bio); /* transferred to @rq on success */
1540 retry:
1541 rq = __get_request(rl, op, bio, flags, gfp);
1542 if (!IS_ERR(rq))
1543 return rq;
1545 if (op & REQ_NOWAIT) {
1546 blk_put_rl(rl);
1547 return ERR_PTR(-EAGAIN);
1550 if ((flags & BLK_MQ_REQ_NOWAIT) || unlikely(blk_queue_dying(q))) {
1551 blk_put_rl(rl);
1552 return rq;
1555 /* wait on @rl and retry */
1556 prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
1557 TASK_UNINTERRUPTIBLE);
1559 trace_block_sleeprq(q, bio, op);
1561 spin_unlock_irq(q->queue_lock);
1562 io_schedule();
1565 * After sleeping, we become a "batching" process and will be able
1566 * to allocate at least one request, and up to a big batch of them
1567 * for a small period time. See ioc_batching, ioc_set_batching
1569 ioc_set_batching(q, current->io_context);
1571 spin_lock_irq(q->queue_lock);
1572 finish_wait(&rl->wait[is_sync], &wait);
1574 goto retry;
1577 /* flags: BLK_MQ_REQ_PREEMPT and/or BLK_MQ_REQ_NOWAIT. */
1578 static struct request *blk_old_get_request(struct request_queue *q,
1579 unsigned int op, blk_mq_req_flags_t flags)
1581 struct request *rq;
1582 gfp_t gfp_mask = flags & BLK_MQ_REQ_NOWAIT ? GFP_ATOMIC : GFP_NOIO;
1583 int ret = 0;
1585 WARN_ON_ONCE(q->mq_ops);
1587 /* create ioc upfront */
1588 create_io_context(gfp_mask, q->node);
1590 ret = blk_queue_enter(q, flags);
1591 if (ret)
1592 return ERR_PTR(ret);
1593 spin_lock_irq(q->queue_lock);
1594 rq = get_request(q, op, NULL, flags, gfp_mask);
1595 if (IS_ERR(rq)) {
1596 spin_unlock_irq(q->queue_lock);
1597 blk_queue_exit(q);
1598 return rq;
1601 /* q->queue_lock is unlocked at this point */
1602 rq->__data_len = 0;
1603 rq->__sector = (sector_t) -1;
1604 rq->bio = rq->biotail = NULL;
1605 return rq;
1609 * blk_get_request - allocate a request
1610 * @q: request queue to allocate a request for
1611 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC.
1612 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT.
1614 struct request *blk_get_request(struct request_queue *q, unsigned int op,
1615 blk_mq_req_flags_t flags)
1617 struct request *req;
1619 WARN_ON_ONCE(op & REQ_NOWAIT);
1620 WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT));
1622 if (q->mq_ops) {
1623 req = blk_mq_alloc_request(q, op, flags);
1624 if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn)
1625 q->mq_ops->initialize_rq_fn(req);
1626 } else {
1627 req = blk_old_get_request(q, op, flags);
1628 if (!IS_ERR(req) && q->initialize_rq_fn)
1629 q->initialize_rq_fn(req);
1632 return req;
1634 EXPORT_SYMBOL(blk_get_request);
1637 * blk_requeue_request - put a request back on queue
1638 * @q: request queue where request should be inserted
1639 * @rq: request to be inserted
1641 * Description:
1642 * Drivers often keep queueing requests until the hardware cannot accept
1643 * more, when that condition happens we need to put the request back
1644 * on the queue. Must be called with queue lock held.
1646 void blk_requeue_request(struct request_queue *q, struct request *rq)
1648 lockdep_assert_held(q->queue_lock);
1649 WARN_ON_ONCE(q->mq_ops);
1651 blk_delete_timer(rq);
1652 blk_clear_rq_complete(rq);
1653 trace_block_rq_requeue(q, rq);
1654 rq_qos_requeue(q, rq);
1656 if (rq->rq_flags & RQF_QUEUED)
1657 blk_queue_end_tag(q, rq);
1659 BUG_ON(blk_queued_rq(rq));
1661 elv_requeue_request(q, rq);
1663 EXPORT_SYMBOL(blk_requeue_request);
1665 static void add_acct_request(struct request_queue *q, struct request *rq,
1666 int where)
1668 blk_account_io_start(rq, true);
1669 __elv_add_request(q, rq, where);
1672 static void part_round_stats_single(struct request_queue *q, int cpu,
1673 struct hd_struct *part, unsigned long now,
1674 unsigned int inflight)
1676 if (inflight) {
1677 __part_stat_add(cpu, part, time_in_queue,
1678 inflight * (now - part->stamp));
1679 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
1681 part->stamp = now;
1685 * part_round_stats() - Round off the performance stats on a struct disk_stats.
1686 * @q: target block queue
1687 * @cpu: cpu number for stats access
1688 * @part: target partition
1690 * The average IO queue length and utilisation statistics are maintained
1691 * by observing the current state of the queue length and the amount of
1692 * time it has been in this state for.
1694 * Normally, that accounting is done on IO completion, but that can result
1695 * in more than a second's worth of IO being accounted for within any one
1696 * second, leading to >100% utilisation. To deal with that, we call this
1697 * function to do a round-off before returning the results when reading
1698 * /proc/diskstats. This accounts immediately for all queue usage up to
1699 * the current jiffies and restarts the counters again.
1701 void part_round_stats(struct request_queue *q, int cpu, struct hd_struct *part)
1703 struct hd_struct *part2 = NULL;
1704 unsigned long now = jiffies;
1705 unsigned int inflight[2];
1706 int stats = 0;
1708 if (part->stamp != now)
1709 stats |= 1;
1711 if (part->partno) {
1712 part2 = &part_to_disk(part)->part0;
1713 if (part2->stamp != now)
1714 stats |= 2;
1717 if (!stats)
1718 return;
1720 part_in_flight(q, part, inflight);
1722 if (stats & 2)
1723 part_round_stats_single(q, cpu, part2, now, inflight[1]);
1724 if (stats & 1)
1725 part_round_stats_single(q, cpu, part, now, inflight[0]);
1727 EXPORT_SYMBOL_GPL(part_round_stats);
1729 #ifdef CONFIG_PM
1730 static void blk_pm_put_request(struct request *rq)
1732 if (rq->q->dev && !(rq->rq_flags & RQF_PM) && !--rq->q->nr_pending)
1733 pm_runtime_mark_last_busy(rq->q->dev);
1735 #else
1736 static inline void blk_pm_put_request(struct request *rq) {}
1737 #endif
1739 void __blk_put_request(struct request_queue *q, struct request *req)
1741 req_flags_t rq_flags = req->rq_flags;
1743 if (unlikely(!q))
1744 return;
1746 if (q->mq_ops) {
1747 blk_mq_free_request(req);
1748 return;
1751 lockdep_assert_held(q->queue_lock);
1753 blk_req_zone_write_unlock(req);
1754 blk_pm_put_request(req);
1756 elv_completed_request(q, req);
1758 /* this is a bio leak */
1759 WARN_ON(req->bio != NULL);
1761 rq_qos_done(q, req);
1764 * Request may not have originated from ll_rw_blk. if not,
1765 * it didn't come out of our reserved rq pools
1767 if (rq_flags & RQF_ALLOCED) {
1768 struct request_list *rl = blk_rq_rl(req);
1769 bool sync = op_is_sync(req->cmd_flags);
1771 BUG_ON(!list_empty(&req->queuelist));
1772 BUG_ON(ELV_ON_HASH(req));
1774 blk_free_request(rl, req);
1775 freed_request(rl, sync, rq_flags);
1776 blk_put_rl(rl);
1777 blk_queue_exit(q);
1780 EXPORT_SYMBOL_GPL(__blk_put_request);
1782 void blk_put_request(struct request *req)
1784 struct request_queue *q = req->q;
1786 if (q->mq_ops)
1787 blk_mq_free_request(req);
1788 else {
1789 unsigned long flags;
1791 spin_lock_irqsave(q->queue_lock, flags);
1792 __blk_put_request(q, req);
1793 spin_unlock_irqrestore(q->queue_lock, flags);
1796 EXPORT_SYMBOL(blk_put_request);
1798 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
1799 struct bio *bio)
1801 const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
1803 if (!ll_back_merge_fn(q, req, bio))
1804 return false;
1806 trace_block_bio_backmerge(q, req, bio);
1808 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1809 blk_rq_set_mixed_merge(req);
1811 req->biotail->bi_next = bio;
1812 req->biotail = bio;
1813 req->__data_len += bio->bi_iter.bi_size;
1814 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1816 blk_account_io_start(req, false);
1817 return true;
1820 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
1821 struct bio *bio)
1823 const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
1825 if (!ll_front_merge_fn(q, req, bio))
1826 return false;
1828 trace_block_bio_frontmerge(q, req, bio);
1830 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
1831 blk_rq_set_mixed_merge(req);
1833 bio->bi_next = req->bio;
1834 req->bio = bio;
1836 req->__sector = bio->bi_iter.bi_sector;
1837 req->__data_len += bio->bi_iter.bi_size;
1838 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1840 blk_account_io_start(req, false);
1841 return true;
1844 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
1845 struct bio *bio)
1847 unsigned short segments = blk_rq_nr_discard_segments(req);
1849 if (segments >= queue_max_discard_segments(q))
1850 goto no_merge;
1851 if (blk_rq_sectors(req) + bio_sectors(bio) >
1852 blk_rq_get_max_sectors(req, blk_rq_pos(req)))
1853 goto no_merge;
1855 req->biotail->bi_next = bio;
1856 req->biotail = bio;
1857 req->__data_len += bio->bi_iter.bi_size;
1858 req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
1859 req->nr_phys_segments = segments + 1;
1861 blk_account_io_start(req, false);
1862 return true;
1863 no_merge:
1864 req_set_nomerge(q, req);
1865 return false;
1869 * blk_attempt_plug_merge - try to merge with %current's plugged list
1870 * @q: request_queue new bio is being queued at
1871 * @bio: new bio being queued
1872 * @request_count: out parameter for number of traversed plugged requests
1873 * @same_queue_rq: pointer to &struct request that gets filled in when
1874 * another request associated with @q is found on the plug list
1875 * (optional, may be %NULL)
1877 * Determine whether @bio being queued on @q can be merged with a request
1878 * on %current's plugged list. Returns %true if merge was successful,
1879 * otherwise %false.
1881 * Plugging coalesces IOs from the same issuer for the same purpose without
1882 * going through @q->queue_lock. As such it's more of an issuing mechanism
1883 * than scheduling, and the request, while may have elvpriv data, is not
1884 * added on the elevator at this point. In addition, we don't have
1885 * reliable access to the elevator outside queue lock. Only check basic
1886 * merging parameters without querying the elevator.
1888 * Caller must ensure !blk_queue_nomerges(q) beforehand.
1890 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
1891 unsigned int *request_count,
1892 struct request **same_queue_rq)
1894 struct blk_plug *plug;
1895 struct request *rq;
1896 struct list_head *plug_list;
1898 plug = current->plug;
1899 if (!plug)
1900 return false;
1901 *request_count = 0;
1903 if (q->mq_ops)
1904 plug_list = &plug->mq_list;
1905 else
1906 plug_list = &plug->list;
1908 list_for_each_entry_reverse(rq, plug_list, queuelist) {
1909 bool merged = false;
1911 if (rq->q == q) {
1912 (*request_count)++;
1914 * Only blk-mq multiple hardware queues case checks the
1915 * rq in the same queue, there should be only one such
1916 * rq in a queue
1918 if (same_queue_rq)
1919 *same_queue_rq = rq;
1922 if (rq->q != q || !blk_rq_merge_ok(rq, bio))
1923 continue;
1925 switch (blk_try_merge(rq, bio)) {
1926 case ELEVATOR_BACK_MERGE:
1927 merged = bio_attempt_back_merge(q, rq, bio);
1928 break;
1929 case ELEVATOR_FRONT_MERGE:
1930 merged = bio_attempt_front_merge(q, rq, bio);
1931 break;
1932 case ELEVATOR_DISCARD_MERGE:
1933 merged = bio_attempt_discard_merge(q, rq, bio);
1934 break;
1935 default:
1936 break;
1939 if (merged)
1940 return true;
1943 return false;
1946 unsigned int blk_plug_queued_count(struct request_queue *q)
1948 struct blk_plug *plug;
1949 struct request *rq;
1950 struct list_head *plug_list;
1951 unsigned int ret = 0;
1953 plug = current->plug;
1954 if (!plug)
1955 goto out;
1957 if (q->mq_ops)
1958 plug_list = &plug->mq_list;
1959 else
1960 plug_list = &plug->list;
1962 list_for_each_entry(rq, plug_list, queuelist) {
1963 if (rq->q == q)
1964 ret++;
1966 out:
1967 return ret;
1970 void blk_init_request_from_bio(struct request *req, struct bio *bio)
1972 struct io_context *ioc = rq_ioc(bio);
1974 if (bio->bi_opf & REQ_RAHEAD)
1975 req->cmd_flags |= REQ_FAILFAST_MASK;
1977 req->__sector = bio->bi_iter.bi_sector;
1978 if (ioprio_valid(bio_prio(bio)))
1979 req->ioprio = bio_prio(bio);
1980 else if (ioc)
1981 req->ioprio = ioc->ioprio;
1982 else
1983 req->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
1984 req->write_hint = bio->bi_write_hint;
1985 blk_rq_bio_prep(req->q, req, bio);
1987 EXPORT_SYMBOL_GPL(blk_init_request_from_bio);
1989 static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio)
1991 struct blk_plug *plug;
1992 int where = ELEVATOR_INSERT_SORT;
1993 struct request *req, *free;
1994 unsigned int request_count = 0;
1997 * low level driver can indicate that it wants pages above a
1998 * certain limit bounced to low memory (ie for highmem, or even
1999 * ISA dma in theory)
2001 blk_queue_bounce(q, &bio);
2003 blk_queue_split(q, &bio);
2005 if (!bio_integrity_prep(bio))
2006 return BLK_QC_T_NONE;
2008 if (op_is_flush(bio->bi_opf)) {
2009 spin_lock_irq(q->queue_lock);
2010 where = ELEVATOR_INSERT_FLUSH;
2011 goto get_rq;
2015 * Check if we can merge with the plugged list before grabbing
2016 * any locks.
2018 if (!blk_queue_nomerges(q)) {
2019 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
2020 return BLK_QC_T_NONE;
2021 } else
2022 request_count = blk_plug_queued_count(q);
2024 spin_lock_irq(q->queue_lock);
2026 switch (elv_merge(q, &req, bio)) {
2027 case ELEVATOR_BACK_MERGE:
2028 if (!bio_attempt_back_merge(q, req, bio))
2029 break;
2030 elv_bio_merged(q, req, bio);
2031 free = attempt_back_merge(q, req);
2032 if (free)
2033 __blk_put_request(q, free);
2034 else
2035 elv_merged_request(q, req, ELEVATOR_BACK_MERGE);
2036 goto out_unlock;
2037 case ELEVATOR_FRONT_MERGE:
2038 if (!bio_attempt_front_merge(q, req, bio))
2039 break;
2040 elv_bio_merged(q, req, bio);
2041 free = attempt_front_merge(q, req);
2042 if (free)
2043 __blk_put_request(q, free);
2044 else
2045 elv_merged_request(q, req, ELEVATOR_FRONT_MERGE);
2046 goto out_unlock;
2047 default:
2048 break;
2051 get_rq:
2052 rq_qos_throttle(q, bio, q->queue_lock);
2055 * Grab a free request. This is might sleep but can not fail.
2056 * Returns with the queue unlocked.
2058 blk_queue_enter_live(q);
2059 req = get_request(q, bio->bi_opf, bio, 0, GFP_NOIO);
2060 if (IS_ERR(req)) {
2061 blk_queue_exit(q);
2062 rq_qos_cleanup(q, bio);
2063 if (PTR_ERR(req) == -ENOMEM)
2064 bio->bi_status = BLK_STS_RESOURCE;
2065 else
2066 bio->bi_status = BLK_STS_IOERR;
2067 bio_endio(bio);
2068 goto out_unlock;
2071 rq_qos_track(q, req, bio);
2074 * After dropping the lock and possibly sleeping here, our request
2075 * may now be mergeable after it had proven unmergeable (above).
2076 * We don't worry about that case for efficiency. It won't happen
2077 * often, and the elevators are able to handle it.
2079 blk_init_request_from_bio(req, bio);
2081 if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
2082 req->cpu = raw_smp_processor_id();
2084 plug = current->plug;
2085 if (plug) {
2087 * If this is the first request added after a plug, fire
2088 * of a plug trace.
2090 * @request_count may become stale because of schedule
2091 * out, so check plug list again.
2093 if (!request_count || list_empty(&plug->list))
2094 trace_block_plug(q);
2095 else {
2096 struct request *last = list_entry_rq(plug->list.prev);
2097 if (request_count >= BLK_MAX_REQUEST_COUNT ||
2098 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE) {
2099 blk_flush_plug_list(plug, false);
2100 trace_block_plug(q);
2103 list_add_tail(&req->queuelist, &plug->list);
2104 blk_account_io_start(req, true);
2105 } else {
2106 spin_lock_irq(q->queue_lock);
2107 add_acct_request(q, req, where);
2108 __blk_run_queue(q);
2109 out_unlock:
2110 spin_unlock_irq(q->queue_lock);
2113 return BLK_QC_T_NONE;
2116 static void handle_bad_sector(struct bio *bio, sector_t maxsector)
2118 char b[BDEVNAME_SIZE];
2120 printk(KERN_INFO "attempt to access beyond end of device\n");
2121 printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n",
2122 bio_devname(bio, b), bio->bi_opf,
2123 (unsigned long long)bio_end_sector(bio),
2124 (long long)maxsector);
2127 #ifdef CONFIG_FAIL_MAKE_REQUEST
2129 static DECLARE_FAULT_ATTR(fail_make_request);
2131 static int __init setup_fail_make_request(char *str)
2133 return setup_fault_attr(&fail_make_request, str);
2135 __setup("fail_make_request=", setup_fail_make_request);
2137 static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
2139 return part->make_it_fail && should_fail(&fail_make_request, bytes);
2142 static int __init fail_make_request_debugfs(void)
2144 struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
2145 NULL, &fail_make_request);
2147 return PTR_ERR_OR_ZERO(dir);
2150 late_initcall(fail_make_request_debugfs);
2152 #else /* CONFIG_FAIL_MAKE_REQUEST */
2154 static inline bool should_fail_request(struct hd_struct *part,
2155 unsigned int bytes)
2157 return false;
2160 #endif /* CONFIG_FAIL_MAKE_REQUEST */
2162 static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part)
2164 const int op = bio_op(bio);
2166 if (part->policy && op_is_write(op)) {
2167 char b[BDEVNAME_SIZE];
2169 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
2170 return false;
2172 WARN_ONCE(1,
2173 "generic_make_request: Trying to write "
2174 "to read-only block-device %s (partno %d)\n",
2175 bio_devname(bio, b), part->partno);
2176 /* Older lvm-tools actually trigger this */
2177 return false;
2180 return false;
2183 static noinline int should_fail_bio(struct bio *bio)
2185 if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size))
2186 return -EIO;
2187 return 0;
2189 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO);
2192 * Check whether this bio extends beyond the end of the device or partition.
2193 * This may well happen - the kernel calls bread() without checking the size of
2194 * the device, e.g., when mounting a file system.
2196 static inline int bio_check_eod(struct bio *bio, sector_t maxsector)
2198 unsigned int nr_sectors = bio_sectors(bio);
2200 if (nr_sectors && maxsector &&
2201 (nr_sectors > maxsector ||
2202 bio->bi_iter.bi_sector > maxsector - nr_sectors)) {
2203 handle_bad_sector(bio, maxsector);
2204 return -EIO;
2206 return 0;
2210 * Remap block n of partition p to block n+start(p) of the disk.
2212 static inline int blk_partition_remap(struct bio *bio)
2214 struct hd_struct *p;
2215 int ret = -EIO;
2217 rcu_read_lock();
2218 p = __disk_get_part(bio->bi_disk, bio->bi_partno);
2219 if (unlikely(!p))
2220 goto out;
2221 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size)))
2222 goto out;
2223 if (unlikely(bio_check_ro(bio, p)))
2224 goto out;
2227 * Zone reset does not include bi_size so bio_sectors() is always 0.
2228 * Include a test for the reset op code and perform the remap if needed.
2230 if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) {
2231 if (bio_check_eod(bio, part_nr_sects_read(p)))
2232 goto out;
2233 bio->bi_iter.bi_sector += p->start_sect;
2234 trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p),
2235 bio->bi_iter.bi_sector - p->start_sect);
2237 bio->bi_partno = 0;
2238 ret = 0;
2239 out:
2240 rcu_read_unlock();
2241 return ret;
2244 static noinline_for_stack bool
2245 generic_make_request_checks(struct bio *bio)
2247 struct request_queue *q;
2248 int nr_sectors = bio_sectors(bio);
2249 blk_status_t status = BLK_STS_IOERR;
2250 char b[BDEVNAME_SIZE];
2252 might_sleep();
2254 q = bio->bi_disk->queue;
2255 if (unlikely(!q)) {
2256 printk(KERN_ERR
2257 "generic_make_request: Trying to access "
2258 "nonexistent block-device %s (%Lu)\n",
2259 bio_devname(bio, b), (long long)bio->bi_iter.bi_sector);
2260 goto end_io;
2264 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
2265 * if queue is not a request based queue.
2267 if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q))
2268 goto not_supported;
2270 if (should_fail_bio(bio))
2271 goto end_io;
2273 if (bio->bi_partno) {
2274 if (unlikely(blk_partition_remap(bio)))
2275 goto end_io;
2276 } else {
2277 if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0)))
2278 goto end_io;
2279 if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk))))
2280 goto end_io;
2284 * Filter flush bio's early so that make_request based
2285 * drivers without flush support don't have to worry
2286 * about them.
2288 if (op_is_flush(bio->bi_opf) &&
2289 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
2290 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
2291 if (!nr_sectors) {
2292 status = BLK_STS_OK;
2293 goto end_io;
2297 switch (bio_op(bio)) {
2298 case REQ_OP_DISCARD:
2299 if (!blk_queue_discard(q))
2300 goto not_supported;
2301 break;
2302 case REQ_OP_SECURE_ERASE:
2303 if (!blk_queue_secure_erase(q))
2304 goto not_supported;
2305 break;
2306 case REQ_OP_WRITE_SAME:
2307 if (!q->limits.max_write_same_sectors)
2308 goto not_supported;
2309 break;
2310 case REQ_OP_ZONE_REPORT:
2311 case REQ_OP_ZONE_RESET:
2312 if (!blk_queue_is_zoned(q))
2313 goto not_supported;
2314 break;
2315 case REQ_OP_WRITE_ZEROES:
2316 if (!q->limits.max_write_zeroes_sectors)
2317 goto not_supported;
2318 break;
2319 default:
2320 break;
2324 * Various block parts want %current->io_context and lazy ioc
2325 * allocation ends up trading a lot of pain for a small amount of
2326 * memory. Just allocate it upfront. This may fail and block
2327 * layer knows how to live with it.
2329 create_io_context(GFP_ATOMIC, q->node);
2331 if (!blkcg_bio_issue_check(q, bio))
2332 return false;
2334 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
2335 trace_block_bio_queue(q, bio);
2336 /* Now that enqueuing has been traced, we need to trace
2337 * completion as well.
2339 bio_set_flag(bio, BIO_TRACE_COMPLETION);
2341 return true;
2343 not_supported:
2344 status = BLK_STS_NOTSUPP;
2345 end_io:
2346 bio->bi_status = status;
2347 bio_endio(bio);
2348 return false;
2352 * generic_make_request - hand a buffer to its device driver for I/O
2353 * @bio: The bio describing the location in memory and on the device.
2355 * generic_make_request() is used to make I/O requests of block
2356 * devices. It is passed a &struct bio, which describes the I/O that needs
2357 * to be done.
2359 * generic_make_request() does not return any status. The
2360 * success/failure status of the request, along with notification of
2361 * completion, is delivered asynchronously through the bio->bi_end_io
2362 * function described (one day) else where.
2364 * The caller of generic_make_request must make sure that bi_io_vec
2365 * are set to describe the memory buffer, and that bi_dev and bi_sector are
2366 * set to describe the device address, and the
2367 * bi_end_io and optionally bi_private are set to describe how
2368 * completion notification should be signaled.
2370 * generic_make_request and the drivers it calls may use bi_next if this
2371 * bio happens to be merged with someone else, and may resubmit the bio to
2372 * a lower device by calling into generic_make_request recursively, which
2373 * means the bio should NOT be touched after the call to ->make_request_fn.
2375 blk_qc_t generic_make_request(struct bio *bio)
2378 * bio_list_on_stack[0] contains bios submitted by the current
2379 * make_request_fn.
2380 * bio_list_on_stack[1] contains bios that were submitted before
2381 * the current make_request_fn, but that haven't been processed
2382 * yet.
2384 struct bio_list bio_list_on_stack[2];
2385 blk_mq_req_flags_t flags = 0;
2386 struct request_queue *q = bio->bi_disk->queue;
2387 blk_qc_t ret = BLK_QC_T_NONE;
2389 if (bio->bi_opf & REQ_NOWAIT)
2390 flags = BLK_MQ_REQ_NOWAIT;
2391 if (bio_flagged(bio, BIO_QUEUE_ENTERED))
2392 blk_queue_enter_live(q);
2393 else if (blk_queue_enter(q, flags) < 0) {
2394 if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT))
2395 bio_wouldblock_error(bio);
2396 else
2397 bio_io_error(bio);
2398 return ret;
2401 if (!generic_make_request_checks(bio))
2402 goto out;
2405 * We only want one ->make_request_fn to be active at a time, else
2406 * stack usage with stacked devices could be a problem. So use
2407 * current->bio_list to keep a list of requests submited by a
2408 * make_request_fn function. current->bio_list is also used as a
2409 * flag to say if generic_make_request is currently active in this
2410 * task or not. If it is NULL, then no make_request is active. If
2411 * it is non-NULL, then a make_request is active, and new requests
2412 * should be added at the tail
2414 if (current->bio_list) {
2415 bio_list_add(&current->bio_list[0], bio);
2416 goto out;
2419 /* following loop may be a bit non-obvious, and so deserves some
2420 * explanation.
2421 * Before entering the loop, bio->bi_next is NULL (as all callers
2422 * ensure that) so we have a list with a single bio.
2423 * We pretend that we have just taken it off a longer list, so
2424 * we assign bio_list to a pointer to the bio_list_on_stack,
2425 * thus initialising the bio_list of new bios to be
2426 * added. ->make_request() may indeed add some more bios
2427 * through a recursive call to generic_make_request. If it
2428 * did, we find a non-NULL value in bio_list and re-enter the loop
2429 * from the top. In this case we really did just take the bio
2430 * of the top of the list (no pretending) and so remove it from
2431 * bio_list, and call into ->make_request() again.
2433 BUG_ON(bio->bi_next);
2434 bio_list_init(&bio_list_on_stack[0]);
2435 current->bio_list = bio_list_on_stack;
2436 do {
2437 bool enter_succeeded = true;
2439 if (unlikely(q != bio->bi_disk->queue)) {
2440 if (q)
2441 blk_queue_exit(q);
2442 q = bio->bi_disk->queue;
2443 flags = 0;
2444 if (bio->bi_opf & REQ_NOWAIT)
2445 flags = BLK_MQ_REQ_NOWAIT;
2446 if (blk_queue_enter(q, flags) < 0) {
2447 enter_succeeded = false;
2448 q = NULL;
2452 if (enter_succeeded) {
2453 struct bio_list lower, same;
2455 /* Create a fresh bio_list for all subordinate requests */
2456 bio_list_on_stack[1] = bio_list_on_stack[0];
2457 bio_list_init(&bio_list_on_stack[0]);
2458 ret = q->make_request_fn(q, bio);
2460 /* sort new bios into those for a lower level
2461 * and those for the same level
2463 bio_list_init(&lower);
2464 bio_list_init(&same);
2465 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
2466 if (q == bio->bi_disk->queue)
2467 bio_list_add(&same, bio);
2468 else
2469 bio_list_add(&lower, bio);
2470 /* now assemble so we handle the lowest level first */
2471 bio_list_merge(&bio_list_on_stack[0], &lower);
2472 bio_list_merge(&bio_list_on_stack[0], &same);
2473 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
2474 } else {
2475 if (unlikely(!blk_queue_dying(q) &&
2476 (bio->bi_opf & REQ_NOWAIT)))
2477 bio_wouldblock_error(bio);
2478 else
2479 bio_io_error(bio);
2481 bio = bio_list_pop(&bio_list_on_stack[0]);
2482 } while (bio);
2483 current->bio_list = NULL; /* deactivate */
2485 out:
2486 if (q)
2487 blk_queue_exit(q);
2488 return ret;
2490 EXPORT_SYMBOL(generic_make_request);
2493 * direct_make_request - hand a buffer directly to its device driver for I/O
2494 * @bio: The bio describing the location in memory and on the device.
2496 * This function behaves like generic_make_request(), but does not protect
2497 * against recursion. Must only be used if the called driver is known
2498 * to not call generic_make_request (or direct_make_request) again from
2499 * its make_request function. (Calling direct_make_request again from
2500 * a workqueue is perfectly fine as that doesn't recurse).
2502 blk_qc_t direct_make_request(struct bio *bio)
2504 struct request_queue *q = bio->bi_disk->queue;
2505 bool nowait = bio->bi_opf & REQ_NOWAIT;
2506 blk_qc_t ret;
2508 if (!generic_make_request_checks(bio))
2509 return BLK_QC_T_NONE;
2511 if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) {
2512 if (nowait && !blk_queue_dying(q))
2513 bio->bi_status = BLK_STS_AGAIN;
2514 else
2515 bio->bi_status = BLK_STS_IOERR;
2516 bio_endio(bio);
2517 return BLK_QC_T_NONE;
2520 ret = q->make_request_fn(q, bio);
2521 blk_queue_exit(q);
2522 return ret;
2524 EXPORT_SYMBOL_GPL(direct_make_request);
2527 * submit_bio - submit a bio to the block device layer for I/O
2528 * @bio: The &struct bio which describes the I/O
2530 * submit_bio() is very similar in purpose to generic_make_request(), and
2531 * uses that function to do most of the work. Both are fairly rough
2532 * interfaces; @bio must be presetup and ready for I/O.
2535 blk_qc_t submit_bio(struct bio *bio)
2538 * If it's a regular read/write or a barrier with data attached,
2539 * go through the normal accounting stuff before submission.
2541 if (bio_has_data(bio)) {
2542 unsigned int count;
2544 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
2545 count = queue_logical_block_size(bio->bi_disk->queue) >> 9;
2546 else
2547 count = bio_sectors(bio);
2549 if (op_is_write(bio_op(bio))) {
2550 count_vm_events(PGPGOUT, count);
2551 } else {
2552 task_io_account_read(bio->bi_iter.bi_size);
2553 count_vm_events(PGPGIN, count);
2556 if (unlikely(block_dump)) {
2557 char b[BDEVNAME_SIZE];
2558 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
2559 current->comm, task_pid_nr(current),
2560 op_is_write(bio_op(bio)) ? "WRITE" : "READ",
2561 (unsigned long long)bio->bi_iter.bi_sector,
2562 bio_devname(bio, b), count);
2566 return generic_make_request(bio);
2568 EXPORT_SYMBOL(submit_bio);
2570 bool blk_poll(struct request_queue *q, blk_qc_t cookie)
2572 if (!q->poll_fn || !blk_qc_t_valid(cookie))
2573 return false;
2575 if (current->plug)
2576 blk_flush_plug_list(current->plug, false);
2577 return q->poll_fn(q, cookie);
2579 EXPORT_SYMBOL_GPL(blk_poll);
2582 * blk_cloned_rq_check_limits - Helper function to check a cloned request
2583 * for new the queue limits
2584 * @q: the queue
2585 * @rq: the request being checked
2587 * Description:
2588 * @rq may have been made based on weaker limitations of upper-level queues
2589 * in request stacking drivers, and it may violate the limitation of @q.
2590 * Since the block layer and the underlying device driver trust @rq
2591 * after it is inserted to @q, it should be checked against @q before
2592 * the insertion using this generic function.
2594 * Request stacking drivers like request-based dm may change the queue
2595 * limits when retrying requests on other queues. Those requests need
2596 * to be checked against the new queue limits again during dispatch.
2598 static int blk_cloned_rq_check_limits(struct request_queue *q,
2599 struct request *rq)
2601 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) {
2602 printk(KERN_ERR "%s: over max size limit.\n", __func__);
2603 return -EIO;
2607 * queue's settings related to segment counting like q->bounce_pfn
2608 * may differ from that of other stacking queues.
2609 * Recalculate it to check the request correctly on this queue's
2610 * limitation.
2612 blk_recalc_rq_segments(rq);
2613 if (rq->nr_phys_segments > queue_max_segments(q)) {
2614 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
2615 return -EIO;
2618 return 0;
2622 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
2623 * @q: the queue to submit the request
2624 * @rq: the request being queued
2626 blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq)
2628 unsigned long flags;
2629 int where = ELEVATOR_INSERT_BACK;
2631 if (blk_cloned_rq_check_limits(q, rq))
2632 return BLK_STS_IOERR;
2634 if (rq->rq_disk &&
2635 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
2636 return BLK_STS_IOERR;
2638 if (q->mq_ops) {
2639 if (blk_queue_io_stat(q))
2640 blk_account_io_start(rq, true);
2642 * Since we have a scheduler attached on the top device,
2643 * bypass a potential scheduler on the bottom device for
2644 * insert.
2646 return blk_mq_request_issue_directly(rq);
2649 spin_lock_irqsave(q->queue_lock, flags);
2650 if (unlikely(blk_queue_dying(q))) {
2651 spin_unlock_irqrestore(q->queue_lock, flags);
2652 return BLK_STS_IOERR;
2656 * Submitting request must be dequeued before calling this function
2657 * because it will be linked to another request_queue
2659 BUG_ON(blk_queued_rq(rq));
2661 if (op_is_flush(rq->cmd_flags))
2662 where = ELEVATOR_INSERT_FLUSH;
2664 add_acct_request(q, rq, where);
2665 if (where == ELEVATOR_INSERT_FLUSH)
2666 __blk_run_queue(q);
2667 spin_unlock_irqrestore(q->queue_lock, flags);
2669 return BLK_STS_OK;
2671 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
2674 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
2675 * @rq: request to examine
2677 * Description:
2678 * A request could be merge of IOs which require different failure
2679 * handling. This function determines the number of bytes which
2680 * can be failed from the beginning of the request without
2681 * crossing into area which need to be retried further.
2683 * Return:
2684 * The number of bytes to fail.
2686 unsigned int blk_rq_err_bytes(const struct request *rq)
2688 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
2689 unsigned int bytes = 0;
2690 struct bio *bio;
2692 if (!(rq->rq_flags & RQF_MIXED_MERGE))
2693 return blk_rq_bytes(rq);
2696 * Currently the only 'mixing' which can happen is between
2697 * different fastfail types. We can safely fail portions
2698 * which have all the failfast bits that the first one has -
2699 * the ones which are at least as eager to fail as the first
2700 * one.
2702 for (bio = rq->bio; bio; bio = bio->bi_next) {
2703 if ((bio->bi_opf & ff) != ff)
2704 break;
2705 bytes += bio->bi_iter.bi_size;
2708 /* this could lead to infinite loop */
2709 BUG_ON(blk_rq_bytes(rq) && !bytes);
2710 return bytes;
2712 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
2714 void blk_account_io_completion(struct request *req, unsigned int bytes)
2716 if (blk_do_io_stat(req)) {
2717 const int sgrp = op_stat_group(req_op(req));
2718 struct hd_struct *part;
2719 int cpu;
2721 cpu = part_stat_lock();
2722 part = req->part;
2723 part_stat_add(cpu, part, sectors[sgrp], bytes >> 9);
2724 part_stat_unlock();
2728 void blk_account_io_done(struct request *req, u64 now)
2731 * Account IO completion. flush_rq isn't accounted as a
2732 * normal IO on queueing nor completion. Accounting the
2733 * containing request is enough.
2735 if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) {
2736 unsigned long duration;
2737 const int sgrp = op_stat_group(req_op(req));
2738 struct hd_struct *part;
2739 int cpu;
2741 duration = nsecs_to_jiffies(now - req->start_time_ns);
2742 cpu = part_stat_lock();
2743 part = req->part;
2745 part_stat_inc(cpu, part, ios[sgrp]);
2746 part_stat_add(cpu, part, ticks[sgrp], duration);
2747 part_round_stats(req->q, cpu, part);
2748 part_dec_in_flight(req->q, part, rq_data_dir(req));
2750 hd_struct_put(part);
2751 part_stat_unlock();
2755 #ifdef CONFIG_PM
2757 * Don't process normal requests when queue is suspended
2758 * or in the process of suspending/resuming
2760 static bool blk_pm_allow_request(struct request *rq)
2762 switch (rq->q->rpm_status) {
2763 case RPM_RESUMING:
2764 case RPM_SUSPENDING:
2765 return rq->rq_flags & RQF_PM;
2766 case RPM_SUSPENDED:
2767 return false;
2768 default:
2769 return true;
2772 #else
2773 static bool blk_pm_allow_request(struct request *rq)
2775 return true;
2777 #endif
2779 void blk_account_io_start(struct request *rq, bool new_io)
2781 struct hd_struct *part;
2782 int rw = rq_data_dir(rq);
2783 int cpu;
2785 if (!blk_do_io_stat(rq))
2786 return;
2788 cpu = part_stat_lock();
2790 if (!new_io) {
2791 part = rq->part;
2792 part_stat_inc(cpu, part, merges[rw]);
2793 } else {
2794 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
2795 if (!hd_struct_try_get(part)) {
2797 * The partition is already being removed,
2798 * the request will be accounted on the disk only
2800 * We take a reference on disk->part0 although that
2801 * partition will never be deleted, so we can treat
2802 * it as any other partition.
2804 part = &rq->rq_disk->part0;
2805 hd_struct_get(part);
2807 part_round_stats(rq->q, cpu, part);
2808 part_inc_in_flight(rq->q, part, rw);
2809 rq->part = part;
2812 part_stat_unlock();
2815 static struct request *elv_next_request(struct request_queue *q)
2817 struct request *rq;
2818 struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
2820 WARN_ON_ONCE(q->mq_ops);
2822 while (1) {
2823 list_for_each_entry(rq, &q->queue_head, queuelist) {
2824 if (blk_pm_allow_request(rq))
2825 return rq;
2827 if (rq->rq_flags & RQF_SOFTBARRIER)
2828 break;
2832 * Flush request is running and flush request isn't queueable
2833 * in the drive, we can hold the queue till flush request is
2834 * finished. Even we don't do this, driver can't dispatch next
2835 * requests and will requeue them. And this can improve
2836 * throughput too. For example, we have request flush1, write1,
2837 * flush 2. flush1 is dispatched, then queue is hold, write1
2838 * isn't inserted to queue. After flush1 is finished, flush2
2839 * will be dispatched. Since disk cache is already clean,
2840 * flush2 will be finished very soon, so looks like flush2 is
2841 * folded to flush1.
2842 * Since the queue is hold, a flag is set to indicate the queue
2843 * should be restarted later. Please see flush_end_io() for
2844 * details.
2846 if (fq->flush_pending_idx != fq->flush_running_idx &&
2847 !queue_flush_queueable(q)) {
2848 fq->flush_queue_delayed = 1;
2849 return NULL;
2851 if (unlikely(blk_queue_bypass(q)) ||
2852 !q->elevator->type->ops.sq.elevator_dispatch_fn(q, 0))
2853 return NULL;
2858 * blk_peek_request - peek at the top of a request queue
2859 * @q: request queue to peek at
2861 * Description:
2862 * Return the request at the top of @q. The returned request
2863 * should be started using blk_start_request() before LLD starts
2864 * processing it.
2866 * Return:
2867 * Pointer to the request at the top of @q if available. Null
2868 * otherwise.
2870 struct request *blk_peek_request(struct request_queue *q)
2872 struct request *rq;
2873 int ret;
2875 lockdep_assert_held(q->queue_lock);
2876 WARN_ON_ONCE(q->mq_ops);
2878 while ((rq = elv_next_request(q)) != NULL) {
2879 if (!(rq->rq_flags & RQF_STARTED)) {
2881 * This is the first time the device driver
2882 * sees this request (possibly after
2883 * requeueing). Notify IO scheduler.
2885 if (rq->rq_flags & RQF_SORTED)
2886 elv_activate_rq(q, rq);
2889 * just mark as started even if we don't start
2890 * it, a request that has been delayed should
2891 * not be passed by new incoming requests
2893 rq->rq_flags |= RQF_STARTED;
2894 trace_block_rq_issue(q, rq);
2897 if (!q->boundary_rq || q->boundary_rq == rq) {
2898 q->end_sector = rq_end_sector(rq);
2899 q->boundary_rq = NULL;
2902 if (rq->rq_flags & RQF_DONTPREP)
2903 break;
2905 if (q->dma_drain_size && blk_rq_bytes(rq)) {
2907 * make sure space for the drain appears we
2908 * know we can do this because max_hw_segments
2909 * has been adjusted to be one fewer than the
2910 * device can handle
2912 rq->nr_phys_segments++;
2915 if (!q->prep_rq_fn)
2916 break;
2918 ret = q->prep_rq_fn(q, rq);
2919 if (ret == BLKPREP_OK) {
2920 break;
2921 } else if (ret == BLKPREP_DEFER) {
2923 * the request may have been (partially) prepped.
2924 * we need to keep this request in the front to
2925 * avoid resource deadlock. RQF_STARTED will
2926 * prevent other fs requests from passing this one.
2928 if (q->dma_drain_size && blk_rq_bytes(rq) &&
2929 !(rq->rq_flags & RQF_DONTPREP)) {
2931 * remove the space for the drain we added
2932 * so that we don't add it again
2934 --rq->nr_phys_segments;
2937 rq = NULL;
2938 break;
2939 } else if (ret == BLKPREP_KILL || ret == BLKPREP_INVALID) {
2940 rq->rq_flags |= RQF_QUIET;
2942 * Mark this request as started so we don't trigger
2943 * any debug logic in the end I/O path.
2945 blk_start_request(rq);
2946 __blk_end_request_all(rq, ret == BLKPREP_INVALID ?
2947 BLK_STS_TARGET : BLK_STS_IOERR);
2948 } else {
2949 printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
2950 break;
2954 return rq;
2956 EXPORT_SYMBOL(blk_peek_request);
2958 static void blk_dequeue_request(struct request *rq)
2960 struct request_queue *q = rq->q;
2962 BUG_ON(list_empty(&rq->queuelist));
2963 BUG_ON(ELV_ON_HASH(rq));
2965 list_del_init(&rq->queuelist);
2968 * the time frame between a request being removed from the lists
2969 * and to it is freed is accounted as io that is in progress at
2970 * the driver side.
2972 if (blk_account_rq(rq))
2973 q->in_flight[rq_is_sync(rq)]++;
2977 * blk_start_request - start request processing on the driver
2978 * @req: request to dequeue
2980 * Description:
2981 * Dequeue @req and start timeout timer on it. This hands off the
2982 * request to the driver.
2984 void blk_start_request(struct request *req)
2986 lockdep_assert_held(req->q->queue_lock);
2987 WARN_ON_ONCE(req->q->mq_ops);
2989 blk_dequeue_request(req);
2991 if (test_bit(QUEUE_FLAG_STATS, &req->q->queue_flags)) {
2992 req->io_start_time_ns = ktime_get_ns();
2993 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
2994 req->throtl_size = blk_rq_sectors(req);
2995 #endif
2996 req->rq_flags |= RQF_STATS;
2997 rq_qos_issue(req->q, req);
3000 BUG_ON(blk_rq_is_complete(req));
3001 blk_add_timer(req);
3003 EXPORT_SYMBOL(blk_start_request);
3006 * blk_fetch_request - fetch a request from a request queue
3007 * @q: request queue to fetch a request from
3009 * Description:
3010 * Return the request at the top of @q. The request is started on
3011 * return and LLD can start processing it immediately.
3013 * Return:
3014 * Pointer to the request at the top of @q if available. Null
3015 * otherwise.
3017 struct request *blk_fetch_request(struct request_queue *q)
3019 struct request *rq;
3021 lockdep_assert_held(q->queue_lock);
3022 WARN_ON_ONCE(q->mq_ops);
3024 rq = blk_peek_request(q);
3025 if (rq)
3026 blk_start_request(rq);
3027 return rq;
3029 EXPORT_SYMBOL(blk_fetch_request);
3032 * Steal bios from a request and add them to a bio list.
3033 * The request must not have been partially completed before.
3035 void blk_steal_bios(struct bio_list *list, struct request *rq)
3037 if (rq->bio) {
3038 if (list->tail)
3039 list->tail->bi_next = rq->bio;
3040 else
3041 list->head = rq->bio;
3042 list->tail = rq->biotail;
3044 rq->bio = NULL;
3045 rq->biotail = NULL;
3048 rq->__data_len = 0;
3050 EXPORT_SYMBOL_GPL(blk_steal_bios);
3053 * blk_update_request - Special helper function for request stacking drivers
3054 * @req: the request being processed
3055 * @error: block status code
3056 * @nr_bytes: number of bytes to complete @req
3058 * Description:
3059 * Ends I/O on a number of bytes attached to @req, but doesn't complete
3060 * the request structure even if @req doesn't have leftover.
3061 * If @req has leftover, sets it up for the next range of segments.
3063 * This special helper function is only for request stacking drivers
3064 * (e.g. request-based dm) so that they can handle partial completion.
3065 * Actual device drivers should use blk_end_request instead.
3067 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
3068 * %false return from this function.
3070 * Note:
3071 * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both
3072 * blk_rq_bytes() and in blk_update_request().
3074 * Return:
3075 * %false - this request doesn't have any more data
3076 * %true - this request has more data
3078 bool blk_update_request(struct request *req, blk_status_t error,
3079 unsigned int nr_bytes)
3081 int total_bytes;
3083 trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes);
3085 if (!req->bio)
3086 return false;
3088 if (unlikely(error && !blk_rq_is_passthrough(req) &&
3089 !(req->rq_flags & RQF_QUIET)))
3090 print_req_error(req, error);
3092 blk_account_io_completion(req, nr_bytes);
3094 total_bytes = 0;
3095 while (req->bio) {
3096 struct bio *bio = req->bio;
3097 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
3099 if (bio_bytes == bio->bi_iter.bi_size)
3100 req->bio = bio->bi_next;
3102 /* Completion has already been traced */
3103 bio_clear_flag(bio, BIO_TRACE_COMPLETION);
3104 req_bio_endio(req, bio, bio_bytes, error);
3106 total_bytes += bio_bytes;
3107 nr_bytes -= bio_bytes;
3109 if (!nr_bytes)
3110 break;
3114 * completely done
3116 if (!req->bio) {
3118 * Reset counters so that the request stacking driver
3119 * can find how many bytes remain in the request
3120 * later.
3122 req->__data_len = 0;
3123 return false;
3126 req->__data_len -= total_bytes;
3128 /* update sector only for requests with clear definition of sector */
3129 if (!blk_rq_is_passthrough(req))
3130 req->__sector += total_bytes >> 9;
3132 /* mixed attributes always follow the first bio */
3133 if (req->rq_flags & RQF_MIXED_MERGE) {
3134 req->cmd_flags &= ~REQ_FAILFAST_MASK;
3135 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK;
3138 if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) {
3140 * If total number of sectors is less than the first segment
3141 * size, something has gone terribly wrong.
3143 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
3144 blk_dump_rq_flags(req, "request botched");
3145 req->__data_len = blk_rq_cur_bytes(req);
3148 /* recalculate the number of segments */
3149 blk_recalc_rq_segments(req);
3152 return true;
3154 EXPORT_SYMBOL_GPL(blk_update_request);
3156 static bool blk_update_bidi_request(struct request *rq, blk_status_t error,
3157 unsigned int nr_bytes,
3158 unsigned int bidi_bytes)
3160 if (blk_update_request(rq, error, nr_bytes))
3161 return true;
3163 /* Bidi request must be completed as a whole */
3164 if (unlikely(blk_bidi_rq(rq)) &&
3165 blk_update_request(rq->next_rq, error, bidi_bytes))
3166 return true;
3168 if (blk_queue_add_random(rq->q))
3169 add_disk_randomness(rq->rq_disk);
3171 return false;
3175 * blk_unprep_request - unprepare a request
3176 * @req: the request
3178 * This function makes a request ready for complete resubmission (or
3179 * completion). It happens only after all error handling is complete,
3180 * so represents the appropriate moment to deallocate any resources
3181 * that were allocated to the request in the prep_rq_fn. The queue
3182 * lock is held when calling this.
3184 void blk_unprep_request(struct request *req)
3186 struct request_queue *q = req->q;
3188 req->rq_flags &= ~RQF_DONTPREP;
3189 if (q->unprep_rq_fn)
3190 q->unprep_rq_fn(q, req);
3192 EXPORT_SYMBOL_GPL(blk_unprep_request);
3194 void blk_finish_request(struct request *req, blk_status_t error)
3196 struct request_queue *q = req->q;
3197 u64 now = ktime_get_ns();
3199 lockdep_assert_held(req->q->queue_lock);
3200 WARN_ON_ONCE(q->mq_ops);
3202 if (req->rq_flags & RQF_STATS)
3203 blk_stat_add(req, now);
3205 if (req->rq_flags & RQF_QUEUED)
3206 blk_queue_end_tag(q, req);
3208 BUG_ON(blk_queued_rq(req));
3210 if (unlikely(laptop_mode) && !blk_rq_is_passthrough(req))
3211 laptop_io_completion(req->q->backing_dev_info);
3213 blk_delete_timer(req);
3215 if (req->rq_flags & RQF_DONTPREP)
3216 blk_unprep_request(req);
3218 blk_account_io_done(req, now);
3220 if (req->end_io) {
3221 rq_qos_done(q, req);
3222 req->end_io(req, error);
3223 } else {
3224 if (blk_bidi_rq(req))
3225 __blk_put_request(req->next_rq->q, req->next_rq);
3227 __blk_put_request(q, req);
3230 EXPORT_SYMBOL(blk_finish_request);
3233 * blk_end_bidi_request - Complete a bidi request
3234 * @rq: the request to complete
3235 * @error: block status code
3236 * @nr_bytes: number of bytes to complete @rq
3237 * @bidi_bytes: number of bytes to complete @rq->next_rq
3239 * Description:
3240 * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
3241 * Drivers that supports bidi can safely call this member for any
3242 * type of request, bidi or uni. In the later case @bidi_bytes is
3243 * just ignored.
3245 * Return:
3246 * %false - we are done with this request
3247 * %true - still buffers pending for this request
3249 static bool blk_end_bidi_request(struct request *rq, blk_status_t error,
3250 unsigned int nr_bytes, unsigned int bidi_bytes)
3252 struct request_queue *q = rq->q;
3253 unsigned long flags;
3255 WARN_ON_ONCE(q->mq_ops);
3257 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
3258 return true;
3260 spin_lock_irqsave(q->queue_lock, flags);
3261 blk_finish_request(rq, error);
3262 spin_unlock_irqrestore(q->queue_lock, flags);
3264 return false;
3268 * __blk_end_bidi_request - Complete a bidi request with queue lock held
3269 * @rq: the request to complete
3270 * @error: block status code
3271 * @nr_bytes: number of bytes to complete @rq
3272 * @bidi_bytes: number of bytes to complete @rq->next_rq
3274 * Description:
3275 * Identical to blk_end_bidi_request() except that queue lock is
3276 * assumed to be locked on entry and remains so on return.
3278 * Return:
3279 * %false - we are done with this request
3280 * %true - still buffers pending for this request
3282 static bool __blk_end_bidi_request(struct request *rq, blk_status_t error,
3283 unsigned int nr_bytes, unsigned int bidi_bytes)
3285 lockdep_assert_held(rq->q->queue_lock);
3286 WARN_ON_ONCE(rq->q->mq_ops);
3288 if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
3289 return true;
3291 blk_finish_request(rq, error);
3293 return false;
3297 * blk_end_request - Helper function for drivers to complete the request.
3298 * @rq: the request being processed
3299 * @error: block status code
3300 * @nr_bytes: number of bytes to complete
3302 * Description:
3303 * Ends I/O on a number of bytes attached to @rq.
3304 * If @rq has leftover, sets it up for the next range of segments.
3306 * Return:
3307 * %false - we are done with this request
3308 * %true - still buffers pending for this request
3310 bool blk_end_request(struct request *rq, blk_status_t error,
3311 unsigned int nr_bytes)
3313 WARN_ON_ONCE(rq->q->mq_ops);
3314 return blk_end_bidi_request(rq, error, nr_bytes, 0);
3316 EXPORT_SYMBOL(blk_end_request);
3319 * blk_end_request_all - Helper function for drives to finish the request.
3320 * @rq: the request to finish
3321 * @error: block status code
3323 * Description:
3324 * Completely finish @rq.
3326 void blk_end_request_all(struct request *rq, blk_status_t error)
3328 bool pending;
3329 unsigned int bidi_bytes = 0;
3331 if (unlikely(blk_bidi_rq(rq)))
3332 bidi_bytes = blk_rq_bytes(rq->next_rq);
3334 pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
3335 BUG_ON(pending);
3337 EXPORT_SYMBOL(blk_end_request_all);
3340 * __blk_end_request - Helper function for drivers to complete the request.
3341 * @rq: the request being processed
3342 * @error: block status code
3343 * @nr_bytes: number of bytes to complete
3345 * Description:
3346 * Must be called with queue lock held unlike blk_end_request().
3348 * Return:
3349 * %false - we are done with this request
3350 * %true - still buffers pending for this request
3352 bool __blk_end_request(struct request *rq, blk_status_t error,
3353 unsigned int nr_bytes)
3355 lockdep_assert_held(rq->q->queue_lock);
3356 WARN_ON_ONCE(rq->q->mq_ops);
3358 return __blk_end_bidi_request(rq, error, nr_bytes, 0);
3360 EXPORT_SYMBOL(__blk_end_request);
3363 * __blk_end_request_all - Helper function for drives to finish the request.
3364 * @rq: the request to finish
3365 * @error: block status code
3367 * Description:
3368 * Completely finish @rq. Must be called with queue lock held.
3370 void __blk_end_request_all(struct request *rq, blk_status_t error)
3372 bool pending;
3373 unsigned int bidi_bytes = 0;
3375 lockdep_assert_held(rq->q->queue_lock);
3376 WARN_ON_ONCE(rq->q->mq_ops);
3378 if (unlikely(blk_bidi_rq(rq)))
3379 bidi_bytes = blk_rq_bytes(rq->next_rq);
3381 pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
3382 BUG_ON(pending);
3384 EXPORT_SYMBOL(__blk_end_request_all);
3387 * __blk_end_request_cur - Helper function to finish the current request chunk.
3388 * @rq: the request to finish the current chunk for
3389 * @error: block status code
3391 * Description:
3392 * Complete the current consecutively mapped chunk from @rq. Must
3393 * be called with queue lock held.
3395 * Return:
3396 * %false - we are done with this request
3397 * %true - still buffers pending for this request
3399 bool __blk_end_request_cur(struct request *rq, blk_status_t error)
3401 return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
3403 EXPORT_SYMBOL(__blk_end_request_cur);
3405 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
3406 struct bio *bio)
3408 if (bio_has_data(bio))
3409 rq->nr_phys_segments = bio_phys_segments(q, bio);
3410 else if (bio_op(bio) == REQ_OP_DISCARD)
3411 rq->nr_phys_segments = 1;
3413 rq->__data_len = bio->bi_iter.bi_size;
3414 rq->bio = rq->biotail = bio;
3416 if (bio->bi_disk)
3417 rq->rq_disk = bio->bi_disk;
3420 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
3422 * rq_flush_dcache_pages - Helper function to flush all pages in a request
3423 * @rq: the request to be flushed
3425 * Description:
3426 * Flush all pages in @rq.
3428 void rq_flush_dcache_pages(struct request *rq)
3430 struct req_iterator iter;
3431 struct bio_vec bvec;
3433 rq_for_each_segment(bvec, rq, iter)
3434 flush_dcache_page(bvec.bv_page);
3436 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
3437 #endif
3440 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
3441 * @q : the queue of the device being checked
3443 * Description:
3444 * Check if underlying low-level drivers of a device are busy.
3445 * If the drivers want to export their busy state, they must set own
3446 * exporting function using blk_queue_lld_busy() first.
3448 * Basically, this function is used only by request stacking drivers
3449 * to stop dispatching requests to underlying devices when underlying
3450 * devices are busy. This behavior helps more I/O merging on the queue
3451 * of the request stacking driver and prevents I/O throughput regression
3452 * on burst I/O load.
3454 * Return:
3455 * 0 - Not busy (The request stacking driver should dispatch request)
3456 * 1 - Busy (The request stacking driver should stop dispatching request)
3458 int blk_lld_busy(struct request_queue *q)
3460 if (q->lld_busy_fn)
3461 return q->lld_busy_fn(q);
3463 return 0;
3465 EXPORT_SYMBOL_GPL(blk_lld_busy);
3468 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
3469 * @rq: the clone request to be cleaned up
3471 * Description:
3472 * Free all bios in @rq for a cloned request.
3474 void blk_rq_unprep_clone(struct request *rq)
3476 struct bio *bio;
3478 while ((bio = rq->bio) != NULL) {
3479 rq->bio = bio->bi_next;
3481 bio_put(bio);
3484 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
3487 * Copy attributes of the original request to the clone request.
3488 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
3490 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
3492 dst->cpu = src->cpu;
3493 dst->__sector = blk_rq_pos(src);
3494 dst->__data_len = blk_rq_bytes(src);
3495 if (src->rq_flags & RQF_SPECIAL_PAYLOAD) {
3496 dst->rq_flags |= RQF_SPECIAL_PAYLOAD;
3497 dst->special_vec = src->special_vec;
3499 dst->nr_phys_segments = src->nr_phys_segments;
3500 dst->ioprio = src->ioprio;
3501 dst->extra_len = src->extra_len;
3505 * blk_rq_prep_clone - Helper function to setup clone request
3506 * @rq: the request to be setup
3507 * @rq_src: original request to be cloned
3508 * @bs: bio_set that bios for clone are allocated from
3509 * @gfp_mask: memory allocation mask for bio
3510 * @bio_ctr: setup function to be called for each clone bio.
3511 * Returns %0 for success, non %0 for failure.
3512 * @data: private data to be passed to @bio_ctr
3514 * Description:
3515 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
3516 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
3517 * are not copied, and copying such parts is the caller's responsibility.
3518 * Also, pages which the original bios are pointing to are not copied
3519 * and the cloned bios just point same pages.
3520 * So cloned bios must be completed before original bios, which means
3521 * the caller must complete @rq before @rq_src.
3523 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
3524 struct bio_set *bs, gfp_t gfp_mask,
3525 int (*bio_ctr)(struct bio *, struct bio *, void *),
3526 void *data)
3528 struct bio *bio, *bio_src;
3530 if (!bs)
3531 bs = &fs_bio_set;
3533 __rq_for_each_bio(bio_src, rq_src) {
3534 bio = bio_clone_fast(bio_src, gfp_mask, bs);
3535 if (!bio)
3536 goto free_and_out;
3538 if (bio_ctr && bio_ctr(bio, bio_src, data))
3539 goto free_and_out;
3541 if (rq->bio) {
3542 rq->biotail->bi_next = bio;
3543 rq->biotail = bio;
3544 } else
3545 rq->bio = rq->biotail = bio;
3548 __blk_rq_prep_clone(rq, rq_src);
3550 return 0;
3552 free_and_out:
3553 if (bio)
3554 bio_put(bio);
3555 blk_rq_unprep_clone(rq);
3557 return -ENOMEM;
3559 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
3561 int kblockd_schedule_work(struct work_struct *work)
3563 return queue_work(kblockd_workqueue, work);
3565 EXPORT_SYMBOL(kblockd_schedule_work);
3567 int kblockd_schedule_work_on(int cpu, struct work_struct *work)
3569 return queue_work_on(cpu, kblockd_workqueue, work);
3571 EXPORT_SYMBOL(kblockd_schedule_work_on);
3573 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
3574 unsigned long delay)
3576 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
3578 EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
3581 * blk_start_plug - initialize blk_plug and track it inside the task_struct
3582 * @plug: The &struct blk_plug that needs to be initialized
3584 * Description:
3585 * Tracking blk_plug inside the task_struct will help with auto-flushing the
3586 * pending I/O should the task end up blocking between blk_start_plug() and
3587 * blk_finish_plug(). This is important from a performance perspective, but
3588 * also ensures that we don't deadlock. For instance, if the task is blocking
3589 * for a memory allocation, memory reclaim could end up wanting to free a
3590 * page belonging to that request that is currently residing in our private
3591 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
3592 * this kind of deadlock.
3594 void blk_start_plug(struct blk_plug *plug)
3596 struct task_struct *tsk = current;
3599 * If this is a nested plug, don't actually assign it.
3601 if (tsk->plug)
3602 return;
3604 INIT_LIST_HEAD(&plug->list);
3605 INIT_LIST_HEAD(&plug->mq_list);
3606 INIT_LIST_HEAD(&plug->cb_list);
3608 * Store ordering should not be needed here, since a potential
3609 * preempt will imply a full memory barrier
3611 tsk->plug = plug;
3613 EXPORT_SYMBOL(blk_start_plug);
3615 static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
3617 struct request *rqa = container_of(a, struct request, queuelist);
3618 struct request *rqb = container_of(b, struct request, queuelist);
3620 return !(rqa->q < rqb->q ||
3621 (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
3625 * If 'from_schedule' is true, then postpone the dispatch of requests
3626 * until a safe kblockd context. We due this to avoid accidental big
3627 * additional stack usage in driver dispatch, in places where the originally
3628 * plugger did not intend it.
3630 static void queue_unplugged(struct request_queue *q, unsigned int depth,
3631 bool from_schedule)
3632 __releases(q->queue_lock)
3634 lockdep_assert_held(q->queue_lock);
3636 trace_block_unplug(q, depth, !from_schedule);
3638 if (from_schedule)
3639 blk_run_queue_async(q);
3640 else
3641 __blk_run_queue(q);
3642 spin_unlock_irq(q->queue_lock);
3645 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
3647 LIST_HEAD(callbacks);
3649 while (!list_empty(&plug->cb_list)) {
3650 list_splice_init(&plug->cb_list, &callbacks);
3652 while (!list_empty(&callbacks)) {
3653 struct blk_plug_cb *cb = list_first_entry(&callbacks,
3654 struct blk_plug_cb,
3655 list);
3656 list_del(&cb->list);
3657 cb->callback(cb, from_schedule);
3662 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
3663 int size)
3665 struct blk_plug *plug = current->plug;
3666 struct blk_plug_cb *cb;
3668 if (!plug)
3669 return NULL;
3671 list_for_each_entry(cb, &plug->cb_list, list)
3672 if (cb->callback == unplug && cb->data == data)
3673 return cb;
3675 /* Not currently on the callback list */
3676 BUG_ON(size < sizeof(*cb));
3677 cb = kzalloc(size, GFP_ATOMIC);
3678 if (cb) {
3679 cb->data = data;
3680 cb->callback = unplug;
3681 list_add(&cb->list, &plug->cb_list);
3683 return cb;
3685 EXPORT_SYMBOL(blk_check_plugged);
3687 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
3689 struct request_queue *q;
3690 struct request *rq;
3691 LIST_HEAD(list);
3692 unsigned int depth;
3694 flush_plug_callbacks(plug, from_schedule);
3696 if (!list_empty(&plug->mq_list))
3697 blk_mq_flush_plug_list(plug, from_schedule);
3699 if (list_empty(&plug->list))
3700 return;
3702 list_splice_init(&plug->list, &list);
3704 list_sort(NULL, &list, plug_rq_cmp);
3706 q = NULL;
3707 depth = 0;
3709 while (!list_empty(&list)) {
3710 rq = list_entry_rq(list.next);
3711 list_del_init(&rq->queuelist);
3712 BUG_ON(!rq->q);
3713 if (rq->q != q) {
3715 * This drops the queue lock
3717 if (q)
3718 queue_unplugged(q, depth, from_schedule);
3719 q = rq->q;
3720 depth = 0;
3721 spin_lock_irq(q->queue_lock);
3725 * Short-circuit if @q is dead
3727 if (unlikely(blk_queue_dying(q))) {
3728 __blk_end_request_all(rq, BLK_STS_IOERR);
3729 continue;
3733 * rq is already accounted, so use raw insert
3735 if (op_is_flush(rq->cmd_flags))
3736 __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
3737 else
3738 __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
3740 depth++;
3744 * This drops the queue lock
3746 if (q)
3747 queue_unplugged(q, depth, from_schedule);
3750 void blk_finish_plug(struct blk_plug *plug)
3752 if (plug != current->plug)
3753 return;
3754 blk_flush_plug_list(plug, false);
3756 current->plug = NULL;
3758 EXPORT_SYMBOL(blk_finish_plug);
3760 #ifdef CONFIG_PM
3762 * blk_pm_runtime_init - Block layer runtime PM initialization routine
3763 * @q: the queue of the device
3764 * @dev: the device the queue belongs to
3766 * Description:
3767 * Initialize runtime-PM-related fields for @q and start auto suspend for
3768 * @dev. Drivers that want to take advantage of request-based runtime PM
3769 * should call this function after @dev has been initialized, and its
3770 * request queue @q has been allocated, and runtime PM for it can not happen
3771 * yet(either due to disabled/forbidden or its usage_count > 0). In most
3772 * cases, driver should call this function before any I/O has taken place.
3774 * This function takes care of setting up using auto suspend for the device,
3775 * the autosuspend delay is set to -1 to make runtime suspend impossible
3776 * until an updated value is either set by user or by driver. Drivers do
3777 * not need to touch other autosuspend settings.
3779 * The block layer runtime PM is request based, so only works for drivers
3780 * that use request as their IO unit instead of those directly use bio's.
3782 void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
3784 /* Don't enable runtime PM for blk-mq until it is ready */
3785 if (q->mq_ops) {
3786 pm_runtime_disable(dev);
3787 return;
3790 q->dev = dev;
3791 q->rpm_status = RPM_ACTIVE;
3792 pm_runtime_set_autosuspend_delay(q->dev, -1);
3793 pm_runtime_use_autosuspend(q->dev);
3795 EXPORT_SYMBOL(blk_pm_runtime_init);
3798 * blk_pre_runtime_suspend - Pre runtime suspend check
3799 * @q: the queue of the device
3801 * Description:
3802 * This function will check if runtime suspend is allowed for the device
3803 * by examining if there are any requests pending in the queue. If there
3804 * are requests pending, the device can not be runtime suspended; otherwise,
3805 * the queue's status will be updated to SUSPENDING and the driver can
3806 * proceed to suspend the device.
3808 * For the not allowed case, we mark last busy for the device so that
3809 * runtime PM core will try to autosuspend it some time later.
3811 * This function should be called near the start of the device's
3812 * runtime_suspend callback.
3814 * Return:
3815 * 0 - OK to runtime suspend the device
3816 * -EBUSY - Device should not be runtime suspended
3818 int blk_pre_runtime_suspend(struct request_queue *q)
3820 int ret = 0;
3822 if (!q->dev)
3823 return ret;
3825 spin_lock_irq(q->queue_lock);
3826 if (q->nr_pending) {
3827 ret = -EBUSY;
3828 pm_runtime_mark_last_busy(q->dev);
3829 } else {
3830 q->rpm_status = RPM_SUSPENDING;
3832 spin_unlock_irq(q->queue_lock);
3833 return ret;
3835 EXPORT_SYMBOL(blk_pre_runtime_suspend);
3838 * blk_post_runtime_suspend - Post runtime suspend processing
3839 * @q: the queue of the device
3840 * @err: return value of the device's runtime_suspend function
3842 * Description:
3843 * Update the queue's runtime status according to the return value of the
3844 * device's runtime suspend function and mark last busy for the device so
3845 * that PM core will try to auto suspend the device at a later time.
3847 * This function should be called near the end of the device's
3848 * runtime_suspend callback.
3850 void blk_post_runtime_suspend(struct request_queue *q, int err)
3852 if (!q->dev)
3853 return;
3855 spin_lock_irq(q->queue_lock);
3856 if (!err) {
3857 q->rpm_status = RPM_SUSPENDED;
3858 } else {
3859 q->rpm_status = RPM_ACTIVE;
3860 pm_runtime_mark_last_busy(q->dev);
3862 spin_unlock_irq(q->queue_lock);
3864 EXPORT_SYMBOL(blk_post_runtime_suspend);
3867 * blk_pre_runtime_resume - Pre runtime resume processing
3868 * @q: the queue of the device
3870 * Description:
3871 * Update the queue's runtime status to RESUMING in preparation for the
3872 * runtime resume of the device.
3874 * This function should be called near the start of the device's
3875 * runtime_resume callback.
3877 void blk_pre_runtime_resume(struct request_queue *q)
3879 if (!q->dev)
3880 return;
3882 spin_lock_irq(q->queue_lock);
3883 q->rpm_status = RPM_RESUMING;
3884 spin_unlock_irq(q->queue_lock);
3886 EXPORT_SYMBOL(blk_pre_runtime_resume);
3889 * blk_post_runtime_resume - Post runtime resume processing
3890 * @q: the queue of the device
3891 * @err: return value of the device's runtime_resume function
3893 * Description:
3894 * Update the queue's runtime status according to the return value of the
3895 * device's runtime_resume function. If it is successfully resumed, process
3896 * the requests that are queued into the device's queue when it is resuming
3897 * and then mark last busy and initiate autosuspend for it.
3899 * This function should be called near the end of the device's
3900 * runtime_resume callback.
3902 void blk_post_runtime_resume(struct request_queue *q, int err)
3904 if (!q->dev)
3905 return;
3907 spin_lock_irq(q->queue_lock);
3908 if (!err) {
3909 q->rpm_status = RPM_ACTIVE;
3910 __blk_run_queue(q);
3911 pm_runtime_mark_last_busy(q->dev);
3912 pm_request_autosuspend(q->dev);
3913 } else {
3914 q->rpm_status = RPM_SUSPENDED;
3916 spin_unlock_irq(q->queue_lock);
3918 EXPORT_SYMBOL(blk_post_runtime_resume);
3921 * blk_set_runtime_active - Force runtime status of the queue to be active
3922 * @q: the queue of the device
3924 * If the device is left runtime suspended during system suspend the resume
3925 * hook typically resumes the device and corrects runtime status
3926 * accordingly. However, that does not affect the queue runtime PM status
3927 * which is still "suspended". This prevents processing requests from the
3928 * queue.
3930 * This function can be used in driver's resume hook to correct queue
3931 * runtime PM status and re-enable peeking requests from the queue. It
3932 * should be called before first request is added to the queue.
3934 void blk_set_runtime_active(struct request_queue *q)
3936 spin_lock_irq(q->queue_lock);
3937 q->rpm_status = RPM_ACTIVE;
3938 pm_runtime_mark_last_busy(q->dev);
3939 pm_request_autosuspend(q->dev);
3940 spin_unlock_irq(q->queue_lock);
3942 EXPORT_SYMBOL(blk_set_runtime_active);
3943 #endif
3945 int __init blk_dev_init(void)
3947 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS));
3948 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
3949 FIELD_SIZEOF(struct request, cmd_flags));
3950 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
3951 FIELD_SIZEOF(struct bio, bi_opf));
3953 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
3954 kblockd_workqueue = alloc_workqueue("kblockd",
3955 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
3956 if (!kblockd_workqueue)
3957 panic("Failed to create kblockd\n");
3959 request_cachep = kmem_cache_create("blkdev_requests",
3960 sizeof(struct request), 0, SLAB_PANIC, NULL);
3962 blk_requestq_cachep = kmem_cache_create("request_queue",
3963 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
3965 #ifdef CONFIG_DEBUG_FS
3966 blk_debugfs_root = debugfs_create_dir("block", NULL);
3967 #endif
3969 return 0;