1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics
5 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
6 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
7 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
9 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
13 * This handles all read/write requests to block devices
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/bio.h>
18 #include <linux/blkdev.h>
19 #include <linux/blk-pm.h>
20 #include <linux/blk-integrity.h>
21 #include <linux/highmem.h>
23 #include <linux/pagemap.h>
24 #include <linux/kernel_stat.h>
25 #include <linux/string.h>
26 #include <linux/init.h>
27 #include <linux/completion.h>
28 #include <linux/slab.h>
29 #include <linux/swap.h>
30 #include <linux/writeback.h>
31 #include <linux/task_io_accounting_ops.h>
32 #include <linux/fault-inject.h>
33 #include <linux/list_sort.h>
34 #include <linux/delay.h>
35 #include <linux/ratelimit.h>
36 #include <linux/pm_runtime.h>
37 #include <linux/t10-pi.h>
38 #include <linux/debugfs.h>
39 #include <linux/bpf.h>
40 #include <linux/part_stat.h>
41 #include <linux/sched/sysctl.h>
42 #include <linux/blk-crypto.h>
44 #define CREATE_TRACE_POINTS
45 #include <trace/events/block.h>
48 #include "blk-mq-sched.h"
50 #include "blk-cgroup.h"
51 #include "blk-throttle.h"
53 struct dentry *blk_debugfs_root;
55 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
58 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
59 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
60 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_insert);
62 static DEFINE_IDA(blk_queue_ida);
65 * For queue allocation
67 static struct kmem_cache *blk_requestq_cachep;
70 * Controlling structure to kblockd
72 static struct workqueue_struct *kblockd_workqueue;
75 * blk_queue_flag_set - atomically set a queue flag
76 * @flag: flag to be set
79 void blk_queue_flag_set(unsigned int flag, struct request_queue *q)
81 set_bit(flag, &q->queue_flags);
83 EXPORT_SYMBOL(blk_queue_flag_set);
86 * blk_queue_flag_clear - atomically clear a queue flag
87 * @flag: flag to be cleared
90 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
92 clear_bit(flag, &q->queue_flags);
94 EXPORT_SYMBOL(blk_queue_flag_clear);
97 * blk_queue_flag_test_and_set - atomically test and set a queue flag
98 * @flag: flag to be set
101 * Returns the previous value of @flag - 0 if the flag was not set and 1 if
102 * the flag was already set.
104 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q)
106 return test_and_set_bit(flag, &q->queue_flags);
108 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set);
110 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name
111 static const char *const blk_op_name[] = {
115 REQ_OP_NAME(DISCARD),
116 REQ_OP_NAME(SECURE_ERASE),
117 REQ_OP_NAME(ZONE_RESET),
118 REQ_OP_NAME(ZONE_RESET_ALL),
119 REQ_OP_NAME(ZONE_OPEN),
120 REQ_OP_NAME(ZONE_CLOSE),
121 REQ_OP_NAME(ZONE_FINISH),
122 REQ_OP_NAME(ZONE_APPEND),
123 REQ_OP_NAME(WRITE_ZEROES),
125 REQ_OP_NAME(DRV_OUT),
130 * blk_op_str - Return string XXX in the REQ_OP_XXX.
133 * Description: Centralize block layer function to convert REQ_OP_XXX into
134 * string format. Useful in the debugging and tracing bio or request. For
135 * invalid REQ_OP_XXX it returns string "UNKNOWN".
137 inline const char *blk_op_str(enum req_op op)
139 const char *op_str = "UNKNOWN";
141 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op])
142 op_str = blk_op_name[op];
146 EXPORT_SYMBOL_GPL(blk_op_str);
148 static const struct {
152 [BLK_STS_OK] = { 0, "" },
153 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" },
154 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" },
155 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" },
156 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" },
157 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" },
158 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" },
159 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" },
160 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" },
161 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" },
162 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" },
163 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" },
164 [BLK_STS_OFFLINE] = { -ENODEV, "device offline" },
166 /* device mapper special case, should not leak out: */
167 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" },
169 /* zone device specific errors */
170 [BLK_STS_ZONE_OPEN_RESOURCE] = { -ETOOMANYREFS, "open zones exceeded" },
171 [BLK_STS_ZONE_ACTIVE_RESOURCE] = { -EOVERFLOW, "active zones exceeded" },
173 /* everything else not covered above: */
174 [BLK_STS_IOERR] = { -EIO, "I/O" },
177 blk_status_t errno_to_blk_status(int errno)
181 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) {
182 if (blk_errors[i].errno == errno)
183 return (__force blk_status_t)i;
186 return BLK_STS_IOERR;
188 EXPORT_SYMBOL_GPL(errno_to_blk_status);
190 int blk_status_to_errno(blk_status_t status)
192 int idx = (__force int)status;
194 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
196 return blk_errors[idx].errno;
198 EXPORT_SYMBOL_GPL(blk_status_to_errno);
200 const char *blk_status_to_str(blk_status_t status)
202 int idx = (__force int)status;
204 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
206 return blk_errors[idx].name;
210 * blk_sync_queue - cancel any pending callbacks on a queue
214 * The block layer may perform asynchronous callback activity
215 * on a queue, such as calling the unplug function after a timeout.
216 * A block device may call blk_sync_queue to ensure that any
217 * such activity is cancelled, thus allowing it to release resources
218 * that the callbacks might use. The caller must already have made sure
219 * that its ->submit_bio will not re-add plugging prior to calling
222 * This function does not cancel any asynchronous activity arising
223 * out of elevator or throttling code. That would require elevator_exit()
224 * and blkcg_exit_queue() to be called with queue lock initialized.
227 void blk_sync_queue(struct request_queue *q)
229 del_timer_sync(&q->timeout);
230 cancel_work_sync(&q->timeout_work);
232 EXPORT_SYMBOL(blk_sync_queue);
235 * blk_set_pm_only - increment pm_only counter
236 * @q: request queue pointer
238 void blk_set_pm_only(struct request_queue *q)
240 atomic_inc(&q->pm_only);
242 EXPORT_SYMBOL_GPL(blk_set_pm_only);
244 void blk_clear_pm_only(struct request_queue *q)
248 pm_only = atomic_dec_return(&q->pm_only);
249 WARN_ON_ONCE(pm_only < 0);
251 wake_up_all(&q->mq_freeze_wq);
253 EXPORT_SYMBOL_GPL(blk_clear_pm_only);
255 static void blk_free_queue_rcu(struct rcu_head *rcu_head)
257 struct request_queue *q = container_of(rcu_head,
258 struct request_queue, rcu_head);
260 percpu_ref_exit(&q->q_usage_counter);
261 kmem_cache_free(blk_requestq_cachep, q);
264 static void blk_free_queue(struct request_queue *q)
266 blk_free_queue_stats(q->stats);
270 ida_free(&blk_queue_ida, q->id);
271 call_rcu(&q->rcu_head, blk_free_queue_rcu);
275 * blk_put_queue - decrement the request_queue refcount
276 * @q: the request_queue structure to decrement the refcount for
278 * Decrements the refcount of the request_queue and free it when the refcount
281 void blk_put_queue(struct request_queue *q)
283 if (refcount_dec_and_test(&q->refs))
286 EXPORT_SYMBOL(blk_put_queue);
288 void blk_queue_start_drain(struct request_queue *q)
291 * When queue DYING flag is set, we need to block new req
292 * entering queue, so we call blk_freeze_queue_start() to
293 * prevent I/O from crossing blk_queue_enter().
295 blk_freeze_queue_start(q);
297 blk_mq_wake_waiters(q);
298 /* Make blk_queue_enter() reexamine the DYING flag. */
299 wake_up_all(&q->mq_freeze_wq);
303 * blk_queue_enter() - try to increase q->q_usage_counter
304 * @q: request queue pointer
305 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM
307 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
309 const bool pm = flags & BLK_MQ_REQ_PM;
311 while (!blk_try_enter_queue(q, pm)) {
312 if (flags & BLK_MQ_REQ_NOWAIT)
316 * read pair of barrier in blk_freeze_queue_start(), we need to
317 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and
318 * reading .mq_freeze_depth or queue dying flag, otherwise the
319 * following wait may never return if the two reads are
323 wait_event(q->mq_freeze_wq,
324 (!q->mq_freeze_depth &&
325 blk_pm_resume_queue(pm, q)) ||
327 if (blk_queue_dying(q))
334 int __bio_queue_enter(struct request_queue *q, struct bio *bio)
336 while (!blk_try_enter_queue(q, false)) {
337 struct gendisk *disk = bio->bi_bdev->bd_disk;
339 if (bio->bi_opf & REQ_NOWAIT) {
340 if (test_bit(GD_DEAD, &disk->state))
342 bio_wouldblock_error(bio);
347 * read pair of barrier in blk_freeze_queue_start(), we need to
348 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and
349 * reading .mq_freeze_depth or queue dying flag, otherwise the
350 * following wait may never return if the two reads are
354 wait_event(q->mq_freeze_wq,
355 (!q->mq_freeze_depth &&
356 blk_pm_resume_queue(false, q)) ||
357 test_bit(GD_DEAD, &disk->state));
358 if (test_bit(GD_DEAD, &disk->state))
368 void blk_queue_exit(struct request_queue *q)
370 percpu_ref_put(&q->q_usage_counter);
373 static void blk_queue_usage_counter_release(struct percpu_ref *ref)
375 struct request_queue *q =
376 container_of(ref, struct request_queue, q_usage_counter);
378 wake_up_all(&q->mq_freeze_wq);
381 static void blk_rq_timed_out_timer(struct timer_list *t)
383 struct request_queue *q = from_timer(q, t, timeout);
385 kblockd_schedule_work(&q->timeout_work);
388 static void blk_timeout_work(struct work_struct *work)
392 struct request_queue *blk_alloc_queue(int node_id)
394 struct request_queue *q;
396 q = kmem_cache_alloc_node(blk_requestq_cachep, GFP_KERNEL | __GFP_ZERO,
401 q->last_merge = NULL;
403 q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL);
407 q->stats = blk_alloc_queue_stats();
413 atomic_set(&q->nr_active_requests_shared_tags, 0);
415 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
416 INIT_WORK(&q->timeout_work, blk_timeout_work);
417 INIT_LIST_HEAD(&q->icq_list);
419 refcount_set(&q->refs, 1);
420 mutex_init(&q->debugfs_mutex);
421 mutex_init(&q->sysfs_lock);
422 mutex_init(&q->sysfs_dir_lock);
423 mutex_init(&q->rq_qos_mutex);
424 spin_lock_init(&q->queue_lock);
426 init_waitqueue_head(&q->mq_freeze_wq);
427 mutex_init(&q->mq_freeze_lock);
430 * Init percpu_ref in atomic mode so that it's faster to shutdown.
431 * See blk_register_queue() for details.
433 if (percpu_ref_init(&q->q_usage_counter,
434 blk_queue_usage_counter_release,
435 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
438 blk_set_default_limits(&q->limits);
439 q->nr_requests = BLKDEV_DEFAULT_RQ;
444 blk_free_queue_stats(q->stats);
446 ida_free(&blk_queue_ida, q->id);
448 kmem_cache_free(blk_requestq_cachep, q);
453 * blk_get_queue - increment the request_queue refcount
454 * @q: the request_queue structure to increment the refcount for
456 * Increment the refcount of the request_queue kobject.
458 * Context: Any context.
460 bool blk_get_queue(struct request_queue *q)
462 if (unlikely(blk_queue_dying(q)))
464 refcount_inc(&q->refs);
467 EXPORT_SYMBOL(blk_get_queue);
469 #ifdef CONFIG_FAIL_MAKE_REQUEST
471 static DECLARE_FAULT_ATTR(fail_make_request);
473 static int __init setup_fail_make_request(char *str)
475 return setup_fault_attr(&fail_make_request, str);
477 __setup("fail_make_request=", setup_fail_make_request);
479 bool should_fail_request(struct block_device *part, unsigned int bytes)
481 return part->bd_make_it_fail && should_fail(&fail_make_request, bytes);
484 static int __init fail_make_request_debugfs(void)
486 struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
487 NULL, &fail_make_request);
489 return PTR_ERR_OR_ZERO(dir);
492 late_initcall(fail_make_request_debugfs);
493 #endif /* CONFIG_FAIL_MAKE_REQUEST */
495 static inline void bio_check_ro(struct bio *bio)
497 if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) {
498 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
500 pr_warn("Trying to write to read-only block-device %pg\n",
502 /* Older lvm-tools actually trigger this */
506 static noinline int should_fail_bio(struct bio *bio)
508 if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size))
512 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO);
515 * Check whether this bio extends beyond the end of the device or partition.
516 * This may well happen - the kernel calls bread() without checking the size of
517 * the device, e.g., when mounting a file system.
519 static inline int bio_check_eod(struct bio *bio)
521 sector_t maxsector = bdev_nr_sectors(bio->bi_bdev);
522 unsigned int nr_sectors = bio_sectors(bio);
525 (nr_sectors > maxsector ||
526 bio->bi_iter.bi_sector > maxsector - nr_sectors)) {
527 pr_info_ratelimited("%s: attempt to access beyond end of device\n"
528 "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n",
529 current->comm, bio->bi_bdev, bio->bi_opf,
530 bio->bi_iter.bi_sector, nr_sectors, maxsector);
537 * Remap block n of partition p to block n+start(p) of the disk.
539 static int blk_partition_remap(struct bio *bio)
541 struct block_device *p = bio->bi_bdev;
543 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size)))
545 if (bio_sectors(bio)) {
546 bio->bi_iter.bi_sector += p->bd_start_sect;
547 trace_block_bio_remap(bio, p->bd_dev,
548 bio->bi_iter.bi_sector -
551 bio_set_flag(bio, BIO_REMAPPED);
556 * Check write append to a zoned block device.
558 static inline blk_status_t blk_check_zone_append(struct request_queue *q,
561 int nr_sectors = bio_sectors(bio);
563 /* Only applicable to zoned block devices */
564 if (!bdev_is_zoned(bio->bi_bdev))
565 return BLK_STS_NOTSUPP;
567 /* The bio sector must point to the start of a sequential zone */
568 if (!bdev_is_zone_start(bio->bi_bdev, bio->bi_iter.bi_sector) ||
569 !bio_zone_is_seq(bio))
570 return BLK_STS_IOERR;
573 * Not allowed to cross zone boundaries. Otherwise, the BIO will be
574 * split and could result in non-contiguous sectors being written in
577 if (nr_sectors > q->limits.chunk_sectors)
578 return BLK_STS_IOERR;
580 /* Make sure the BIO is small enough and will not get split */
581 if (nr_sectors > q->limits.max_zone_append_sectors)
582 return BLK_STS_IOERR;
584 bio->bi_opf |= REQ_NOMERGE;
589 static void __submit_bio(struct bio *bio)
591 if (unlikely(!blk_crypto_bio_prep(&bio)))
594 if (!bio->bi_bdev->bd_has_submit_bio) {
595 blk_mq_submit_bio(bio);
596 } else if (likely(bio_queue_enter(bio) == 0)) {
597 struct gendisk *disk = bio->bi_bdev->bd_disk;
599 disk->fops->submit_bio(bio);
600 blk_queue_exit(disk->queue);
605 * The loop in this function may be a bit non-obvious, and so deserves some
608 * - Before entering the loop, bio->bi_next is NULL (as all callers ensure
609 * that), so we have a list with a single bio.
610 * - We pretend that we have just taken it off a longer list, so we assign
611 * bio_list to a pointer to the bio_list_on_stack, thus initialising the
612 * bio_list of new bios to be added. ->submit_bio() may indeed add some more
613 * bios through a recursive call to submit_bio_noacct. If it did, we find a
614 * non-NULL value in bio_list and re-enter the loop from the top.
615 * - In this case we really did just take the bio of the top of the list (no
616 * pretending) and so remove it from bio_list, and call into ->submit_bio()
619 * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio.
620 * bio_list_on_stack[1] contains bios that were submitted before the current
621 * ->submit_bio, but that haven't been processed yet.
623 static void __submit_bio_noacct(struct bio *bio)
625 struct bio_list bio_list_on_stack[2];
627 BUG_ON(bio->bi_next);
629 bio_list_init(&bio_list_on_stack[0]);
630 current->bio_list = bio_list_on_stack;
633 struct request_queue *q = bdev_get_queue(bio->bi_bdev);
634 struct bio_list lower, same;
637 * Create a fresh bio_list for all subordinate requests.
639 bio_list_on_stack[1] = bio_list_on_stack[0];
640 bio_list_init(&bio_list_on_stack[0]);
645 * Sort new bios into those for a lower level and those for the
648 bio_list_init(&lower);
649 bio_list_init(&same);
650 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
651 if (q == bdev_get_queue(bio->bi_bdev))
652 bio_list_add(&same, bio);
654 bio_list_add(&lower, bio);
657 * Now assemble so we handle the lowest level first.
659 bio_list_merge(&bio_list_on_stack[0], &lower);
660 bio_list_merge(&bio_list_on_stack[0], &same);
661 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
662 } while ((bio = bio_list_pop(&bio_list_on_stack[0])));
664 current->bio_list = NULL;
667 static void __submit_bio_noacct_mq(struct bio *bio)
669 struct bio_list bio_list[2] = { };
671 current->bio_list = bio_list;
675 } while ((bio = bio_list_pop(&bio_list[0])));
677 current->bio_list = NULL;
680 void submit_bio_noacct_nocheck(struct bio *bio)
682 blk_cgroup_bio_start(bio);
683 blkcg_bio_issue_init(bio);
685 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
686 trace_block_bio_queue(bio);
688 * Now that enqueuing has been traced, we need to trace
689 * completion as well.
691 bio_set_flag(bio, BIO_TRACE_COMPLETION);
695 * We only want one ->submit_bio to be active at a time, else stack
696 * usage with stacked devices could be a problem. Use current->bio_list
697 * to collect a list of requests submited by a ->submit_bio method while
698 * it is active, and then process them after it returned.
700 if (current->bio_list)
701 bio_list_add(¤t->bio_list[0], bio);
702 else if (!bio->bi_bdev->bd_has_submit_bio)
703 __submit_bio_noacct_mq(bio);
705 __submit_bio_noacct(bio);
709 * submit_bio_noacct - re-submit a bio to the block device layer for I/O
710 * @bio: The bio describing the location in memory and on the device.
712 * This is a version of submit_bio() that shall only be used for I/O that is
713 * resubmitted to lower level drivers by stacking block drivers. All file
714 * systems and other upper level users of the block layer should use
715 * submit_bio() instead.
717 void submit_bio_noacct(struct bio *bio)
719 struct block_device *bdev = bio->bi_bdev;
720 struct request_queue *q = bdev_get_queue(bdev);
721 blk_status_t status = BLK_STS_IOERR;
722 struct blk_plug *plug;
726 plug = blk_mq_plug(bio);
727 if (plug && plug->nowait)
728 bio->bi_opf |= REQ_NOWAIT;
731 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
732 * if queue does not support NOWAIT.
734 if ((bio->bi_opf & REQ_NOWAIT) && !bdev_nowait(bdev))
737 if (should_fail_bio(bio))
740 if (!bio_flagged(bio, BIO_REMAPPED)) {
741 if (unlikely(bio_check_eod(bio)))
743 if (bdev->bd_partno && unlikely(blk_partition_remap(bio)))
748 * Filter flush bio's early so that bio based drivers without flush
749 * support don't have to worry about them.
751 if (op_is_flush(bio->bi_opf)) {
752 if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_WRITE &&
753 bio_op(bio) != REQ_OP_ZONE_APPEND))
755 if (!test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
756 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
757 if (!bio_sectors(bio)) {
764 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
765 bio_clear_polled(bio);
767 switch (bio_op(bio)) {
769 if (!bdev_max_discard_sectors(bdev))
772 case REQ_OP_SECURE_ERASE:
773 if (!bdev_max_secure_erase_sectors(bdev))
776 case REQ_OP_ZONE_APPEND:
777 status = blk_check_zone_append(q, bio);
778 if (status != BLK_STS_OK)
781 case REQ_OP_ZONE_RESET:
782 case REQ_OP_ZONE_OPEN:
783 case REQ_OP_ZONE_CLOSE:
784 case REQ_OP_ZONE_FINISH:
785 if (!bdev_is_zoned(bio->bi_bdev))
788 case REQ_OP_ZONE_RESET_ALL:
789 if (!bdev_is_zoned(bio->bi_bdev) || !blk_queue_zone_resetall(q))
792 case REQ_OP_WRITE_ZEROES:
793 if (!q->limits.max_write_zeroes_sectors)
800 if (blk_throtl_bio(bio))
802 submit_bio_noacct_nocheck(bio);
806 status = BLK_STS_NOTSUPP;
808 bio->bi_status = status;
811 EXPORT_SYMBOL(submit_bio_noacct);
814 * submit_bio - submit a bio to the block device layer for I/O
815 * @bio: The &struct bio which describes the I/O
817 * submit_bio() is used to submit I/O requests to block devices. It is passed a
818 * fully set up &struct bio that describes the I/O that needs to be done. The
819 * bio will be send to the device described by the bi_bdev field.
821 * The success/failure status of the request, along with notification of
822 * completion, is delivered asynchronously through the ->bi_end_io() callback
823 * in @bio. The bio must NOT be touched by the caller until ->bi_end_io() has
826 void submit_bio(struct bio *bio)
828 if (bio_op(bio) == REQ_OP_READ) {
829 task_io_account_read(bio->bi_iter.bi_size);
830 count_vm_events(PGPGIN, bio_sectors(bio));
831 } else if (bio_op(bio) == REQ_OP_WRITE) {
832 count_vm_events(PGPGOUT, bio_sectors(bio));
835 submit_bio_noacct(bio);
837 EXPORT_SYMBOL(submit_bio);
840 * bio_poll - poll for BIO completions
841 * @bio: bio to poll for
842 * @iob: batches of IO
843 * @flags: BLK_POLL_* flags that control the behavior
845 * Poll for completions on queue associated with the bio. Returns number of
846 * completed entries found.
848 * Note: the caller must either be the context that submitted @bio, or
849 * be in a RCU critical section to prevent freeing of @bio.
851 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags)
853 blk_qc_t cookie = READ_ONCE(bio->bi_cookie);
854 struct block_device *bdev;
855 struct request_queue *q;
858 bdev = READ_ONCE(bio->bi_bdev);
862 q = bdev_get_queue(bdev);
863 if (cookie == BLK_QC_T_NONE ||
864 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
868 * As the requests that require a zone lock are not plugged in the
869 * first place, directly accessing the plug instead of using
870 * blk_mq_plug() should not have any consequences during flushing for
873 blk_flush_plug(current->plug, false);
876 * We need to be able to enter a frozen queue, similar to how
877 * timeouts also need to do that. If that is blocked, then we can
878 * have pending IO when a queue freeze is started, and then the
879 * wait for the freeze to finish will wait for polled requests to
880 * timeout as the poller is preventer from entering the queue and
881 * completing them. As long as we prevent new IO from being queued,
882 * that should be all that matters.
884 if (!percpu_ref_tryget(&q->q_usage_counter))
886 if (queue_is_mq(q)) {
887 ret = blk_mq_poll(q, cookie, iob, flags);
889 struct gendisk *disk = q->disk;
891 if (disk && disk->fops->poll_bio)
892 ret = disk->fops->poll_bio(bio, iob, flags);
897 EXPORT_SYMBOL_GPL(bio_poll);
900 * Helper to implement file_operations.iopoll. Requires the bio to be stored
901 * in iocb->private, and cleared before freeing the bio.
903 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob,
910 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can
911 * point to a freshly allocated bio at this point. If that happens
912 * we have a few cases to consider:
914 * 1) the bio is beeing initialized and bi_bdev is NULL. We can just
915 * simply nothing in this case
916 * 2) the bio points to a not poll enabled device. bio_poll will catch
918 * 3) the bio points to a poll capable device, including but not
919 * limited to the one that the original bio pointed to. In this
920 * case we will call into the actual poll method and poll for I/O,
921 * even if we don't need to, but it won't cause harm either.
923 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev
924 * is still allocated. Because partitions hold a reference to the whole
925 * device bdev and thus disk, the disk is also still valid. Grabbing
926 * a reference to the queue in bio_poll() ensures the hctxs and requests
927 * are still valid as well.
930 bio = READ_ONCE(kiocb->private);
932 ret = bio_poll(bio, iob, flags);
937 EXPORT_SYMBOL_GPL(iocb_bio_iopoll);
939 void update_io_ticks(struct block_device *part, unsigned long now, bool end)
943 stamp = READ_ONCE(part->bd_stamp);
944 if (unlikely(time_after(now, stamp))) {
945 if (likely(try_cmpxchg(&part->bd_stamp, &stamp, now)))
946 __part_stat_add(part, io_ticks, end ? now - stamp : 1);
948 if (part->bd_partno) {
949 part = bdev_whole(part);
954 unsigned long bdev_start_io_acct(struct block_device *bdev, enum req_op op,
955 unsigned long start_time)
958 update_io_ticks(bdev, start_time, false);
959 part_stat_local_inc(bdev, in_flight[op_is_write(op)]);
964 EXPORT_SYMBOL(bdev_start_io_acct);
967 * bio_start_io_acct - start I/O accounting for bio based drivers
968 * @bio: bio to start account for
970 * Returns the start time that should be passed back to bio_end_io_acct().
972 unsigned long bio_start_io_acct(struct bio *bio)
974 return bdev_start_io_acct(bio->bi_bdev, bio_op(bio), jiffies);
976 EXPORT_SYMBOL_GPL(bio_start_io_acct);
978 void bdev_end_io_acct(struct block_device *bdev, enum req_op op,
979 unsigned int sectors, unsigned long start_time)
981 const int sgrp = op_stat_group(op);
982 unsigned long now = READ_ONCE(jiffies);
983 unsigned long duration = now - start_time;
986 update_io_ticks(bdev, now, true);
987 part_stat_inc(bdev, ios[sgrp]);
988 part_stat_add(bdev, sectors[sgrp], sectors);
989 part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration));
990 part_stat_local_dec(bdev, in_flight[op_is_write(op)]);
993 EXPORT_SYMBOL(bdev_end_io_acct);
995 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time,
996 struct block_device *orig_bdev)
998 bdev_end_io_acct(orig_bdev, bio_op(bio), bio_sectors(bio), start_time);
1000 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped);
1003 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
1004 * @q : the queue of the device being checked
1007 * Check if underlying low-level drivers of a device are busy.
1008 * If the drivers want to export their busy state, they must set own
1009 * exporting function using blk_queue_lld_busy() first.
1011 * Basically, this function is used only by request stacking drivers
1012 * to stop dispatching requests to underlying devices when underlying
1013 * devices are busy. This behavior helps more I/O merging on the queue
1014 * of the request stacking driver and prevents I/O throughput regression
1015 * on burst I/O load.
1018 * 0 - Not busy (The request stacking driver should dispatch request)
1019 * 1 - Busy (The request stacking driver should stop dispatching request)
1021 int blk_lld_busy(struct request_queue *q)
1023 if (queue_is_mq(q) && q->mq_ops->busy)
1024 return q->mq_ops->busy(q);
1028 EXPORT_SYMBOL_GPL(blk_lld_busy);
1030 int kblockd_schedule_work(struct work_struct *work)
1032 return queue_work(kblockd_workqueue, work);
1034 EXPORT_SYMBOL(kblockd_schedule_work);
1036 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
1037 unsigned long delay)
1039 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
1041 EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
1043 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios)
1045 struct task_struct *tsk = current;
1048 * If this is a nested plug, don't actually assign it.
1053 plug->mq_list = NULL;
1054 plug->cached_rq = NULL;
1055 plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT);
1057 plug->multiple_queues = false;
1058 plug->has_elevator = false;
1059 plug->nowait = false;
1060 INIT_LIST_HEAD(&plug->cb_list);
1063 * Store ordering should not be needed here, since a potential
1064 * preempt will imply a full memory barrier
1070 * blk_start_plug - initialize blk_plug and track it inside the task_struct
1071 * @plug: The &struct blk_plug that needs to be initialized
1074 * blk_start_plug() indicates to the block layer an intent by the caller
1075 * to submit multiple I/O requests in a batch. The block layer may use
1076 * this hint to defer submitting I/Os from the caller until blk_finish_plug()
1077 * is called. However, the block layer may choose to submit requests
1078 * before a call to blk_finish_plug() if the number of queued I/Os
1079 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than
1080 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if
1081 * the task schedules (see below).
1083 * Tracking blk_plug inside the task_struct will help with auto-flushing the
1084 * pending I/O should the task end up blocking between blk_start_plug() and
1085 * blk_finish_plug(). This is important from a performance perspective, but
1086 * also ensures that we don't deadlock. For instance, if the task is blocking
1087 * for a memory allocation, memory reclaim could end up wanting to free a
1088 * page belonging to that request that is currently residing in our private
1089 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
1090 * this kind of deadlock.
1092 void blk_start_plug(struct blk_plug *plug)
1094 blk_start_plug_nr_ios(plug, 1);
1096 EXPORT_SYMBOL(blk_start_plug);
1098 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
1100 LIST_HEAD(callbacks);
1102 while (!list_empty(&plug->cb_list)) {
1103 list_splice_init(&plug->cb_list, &callbacks);
1105 while (!list_empty(&callbacks)) {
1106 struct blk_plug_cb *cb = list_first_entry(&callbacks,
1109 list_del(&cb->list);
1110 cb->callback(cb, from_schedule);
1115 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
1118 struct blk_plug *plug = current->plug;
1119 struct blk_plug_cb *cb;
1124 list_for_each_entry(cb, &plug->cb_list, list)
1125 if (cb->callback == unplug && cb->data == data)
1128 /* Not currently on the callback list */
1129 BUG_ON(size < sizeof(*cb));
1130 cb = kzalloc(size, GFP_ATOMIC);
1133 cb->callback = unplug;
1134 list_add(&cb->list, &plug->cb_list);
1138 EXPORT_SYMBOL(blk_check_plugged);
1140 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule)
1142 if (!list_empty(&plug->cb_list))
1143 flush_plug_callbacks(plug, from_schedule);
1144 if (!rq_list_empty(plug->mq_list))
1145 blk_mq_flush_plug_list(plug, from_schedule);
1147 * Unconditionally flush out cached requests, even if the unplug
1148 * event came from schedule. Since we know hold references to the
1149 * queue for cached requests, we don't want a blocked task holding
1150 * up a queue freeze/quiesce event.
1152 if (unlikely(!rq_list_empty(plug->cached_rq)))
1153 blk_mq_free_plug_rqs(plug);
1157 * blk_finish_plug - mark the end of a batch of submitted I/O
1158 * @plug: The &struct blk_plug passed to blk_start_plug()
1161 * Indicate that a batch of I/O submissions is complete. This function
1162 * must be paired with an initial call to blk_start_plug(). The intent
1163 * is to allow the block layer to optimize I/O submission. See the
1164 * documentation for blk_start_plug() for more information.
1166 void blk_finish_plug(struct blk_plug *plug)
1168 if (plug == current->plug) {
1169 __blk_flush_plug(plug, false);
1170 current->plug = NULL;
1173 EXPORT_SYMBOL(blk_finish_plug);
1175 void blk_io_schedule(void)
1177 /* Prevent hang_check timer from firing at us during very long I/O */
1178 unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2;
1181 io_schedule_timeout(timeout);
1185 EXPORT_SYMBOL_GPL(blk_io_schedule);
1187 int __init blk_dev_init(void)
1189 BUILD_BUG_ON((__force u32)REQ_OP_LAST >= (1 << REQ_OP_BITS));
1190 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
1191 sizeof_field(struct request, cmd_flags));
1192 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
1193 sizeof_field(struct bio, bi_opf));
1195 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
1196 kblockd_workqueue = alloc_workqueue("kblockd",
1197 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1198 if (!kblockd_workqueue)
1199 panic("Failed to create kblockd\n");
1201 blk_requestq_cachep = kmem_cache_create("request_queue",
1202 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
1204 blk_debugfs_root = debugfs_create_dir("block", NULL);