2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics
4 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
5 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
6 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
8 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
12 * This handles all read/write requests to block devices
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/backing-dev.h>
17 #include <linux/bio.h>
18 #include <linux/blkdev.h>
19 #include <linux/blk-mq.h>
20 #include <linux/highmem.h>
22 #include <linux/kernel_stat.h>
23 #include <linux/string.h>
24 #include <linux/init.h>
25 #include <linux/completion.h>
26 #include <linux/slab.h>
27 #include <linux/swap.h>
28 #include <linux/writeback.h>
29 #include <linux/task_io_accounting_ops.h>
30 #include <linux/fault-inject.h>
31 #include <linux/list_sort.h>
32 #include <linux/delay.h>
33 #include <linux/ratelimit.h>
34 #include <linux/pm_runtime.h>
35 #include <linux/blk-cgroup.h>
36 #include <linux/debugfs.h>
37 #include <linux/bpf.h>
39 #define CREATE_TRACE_POINTS
40 #include <trace/events/block.h>
44 #include "blk-mq-sched.h"
46 #include "blk-rq-qos.h"
48 #ifdef CONFIG_DEBUG_FS
49 struct dentry *blk_debugfs_root;
52 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
53 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
54 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
55 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
58 DEFINE_IDA(blk_queue_ida);
61 * For queue allocation
63 struct kmem_cache *blk_requestq_cachep;
66 * Controlling structure to kblockd
68 static struct workqueue_struct *kblockd_workqueue;
71 * blk_queue_flag_set - atomically set a queue flag
72 * @flag: flag to be set
75 void blk_queue_flag_set(unsigned int flag, struct request_queue *q)
77 set_bit(flag, &q->queue_flags);
79 EXPORT_SYMBOL(blk_queue_flag_set);
82 * blk_queue_flag_clear - atomically clear a queue flag
83 * @flag: flag to be cleared
86 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
88 clear_bit(flag, &q->queue_flags);
90 EXPORT_SYMBOL(blk_queue_flag_clear);
93 * blk_queue_flag_test_and_set - atomically test and set a queue flag
94 * @flag: flag to be set
97 * Returns the previous value of @flag - 0 if the flag was not set and 1 if
98 * the flag was already set.
100 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q)
102 return test_and_set_bit(flag, &q->queue_flags);
104 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set);
106 void blk_rq_init(struct request_queue *q, struct request *rq)
108 memset(rq, 0, sizeof(*rq));
110 INIT_LIST_HEAD(&rq->queuelist);
112 rq->__sector = (sector_t) -1;
113 INIT_HLIST_NODE(&rq->hash);
114 RB_CLEAR_NODE(&rq->rb_node);
116 rq->internal_tag = -1;
117 rq->start_time_ns = ktime_get_ns();
120 EXPORT_SYMBOL(blk_rq_init);
122 static const struct {
126 [BLK_STS_OK] = { 0, "" },
127 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" },
128 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" },
129 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" },
130 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" },
131 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" },
132 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" },
133 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" },
134 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" },
135 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" },
136 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" },
137 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" },
139 /* device mapper special case, should not leak out: */
140 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" },
142 /* everything else not covered above: */
143 [BLK_STS_IOERR] = { -EIO, "I/O" },
146 blk_status_t errno_to_blk_status(int errno)
150 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) {
151 if (blk_errors[i].errno == errno)
152 return (__force blk_status_t)i;
155 return BLK_STS_IOERR;
157 EXPORT_SYMBOL_GPL(errno_to_blk_status);
159 int blk_status_to_errno(blk_status_t status)
161 int idx = (__force int)status;
163 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
165 return blk_errors[idx].errno;
167 EXPORT_SYMBOL_GPL(blk_status_to_errno);
169 static void print_req_error(struct request *req, blk_status_t status)
171 int idx = (__force int)status;
173 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
176 printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
177 __func__, blk_errors[idx].name, req->rq_disk ?
178 req->rq_disk->disk_name : "?",
179 (unsigned long long)blk_rq_pos(req));
182 static void req_bio_endio(struct request *rq, struct bio *bio,
183 unsigned int nbytes, blk_status_t error)
186 bio->bi_status = error;
188 if (unlikely(rq->rq_flags & RQF_QUIET))
189 bio_set_flag(bio, BIO_QUIET);
191 bio_advance(bio, nbytes);
193 /* don't actually finish bio if it's part of flush sequence */
194 if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
198 void blk_dump_rq_flags(struct request *rq, char *msg)
200 printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg,
201 rq->rq_disk ? rq->rq_disk->disk_name : "?",
202 (unsigned long long) rq->cmd_flags);
204 printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
205 (unsigned long long)blk_rq_pos(rq),
206 blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
207 printk(KERN_INFO " bio %p, biotail %p, len %u\n",
208 rq->bio, rq->biotail, blk_rq_bytes(rq));
210 EXPORT_SYMBOL(blk_dump_rq_flags);
213 * blk_sync_queue - cancel any pending callbacks on a queue
217 * The block layer may perform asynchronous callback activity
218 * on a queue, such as calling the unplug function after a timeout.
219 * A block device may call blk_sync_queue to ensure that any
220 * such activity is cancelled, thus allowing it to release resources
221 * that the callbacks might use. The caller must already have made sure
222 * that its ->make_request_fn will not re-add plugging prior to calling
225 * This function does not cancel any asynchronous activity arising
226 * out of elevator or throttling code. That would require elevator_exit()
227 * and blkcg_exit_queue() to be called with queue lock initialized.
230 void blk_sync_queue(struct request_queue *q)
232 del_timer_sync(&q->timeout);
233 cancel_work_sync(&q->timeout_work);
235 if (queue_is_mq(q)) {
236 struct blk_mq_hw_ctx *hctx;
239 cancel_delayed_work_sync(&q->requeue_work);
240 queue_for_each_hw_ctx(q, hctx, i)
241 cancel_delayed_work_sync(&hctx->run_work);
244 EXPORT_SYMBOL(blk_sync_queue);
247 * blk_set_pm_only - increment pm_only counter
248 * @q: request queue pointer
250 void blk_set_pm_only(struct request_queue *q)
252 atomic_inc(&q->pm_only);
254 EXPORT_SYMBOL_GPL(blk_set_pm_only);
256 void blk_clear_pm_only(struct request_queue *q)
260 pm_only = atomic_dec_return(&q->pm_only);
261 WARN_ON_ONCE(pm_only < 0);
263 wake_up_all(&q->mq_freeze_wq);
265 EXPORT_SYMBOL_GPL(blk_clear_pm_only);
267 void blk_put_queue(struct request_queue *q)
269 kobject_put(&q->kobj);
271 EXPORT_SYMBOL(blk_put_queue);
273 void blk_set_queue_dying(struct request_queue *q)
275 blk_queue_flag_set(QUEUE_FLAG_DYING, q);
278 * When queue DYING flag is set, we need to block new req
279 * entering queue, so we call blk_freeze_queue_start() to
280 * prevent I/O from crossing blk_queue_enter().
282 blk_freeze_queue_start(q);
285 blk_mq_wake_waiters(q);
287 /* Make blk_queue_enter() reexamine the DYING flag. */
288 wake_up_all(&q->mq_freeze_wq);
290 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
292 /* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */
293 void blk_exit_queue(struct request_queue *q)
296 * Since the I/O scheduler exit code may access cgroup information,
297 * perform I/O scheduler exit before disassociating from the block
302 elevator_exit(q, q->elevator);
307 * Remove all references to @q from the block cgroup controller before
308 * restoring @q->queue_lock to avoid that restoring this pointer causes
309 * e.g. blkcg_print_blkgs() to crash.
314 * Since the cgroup code may dereference the @q->backing_dev_info
315 * pointer, only decrease its reference count after having removed the
316 * association with the block cgroup controller.
318 bdi_put(q->backing_dev_info);
322 * blk_cleanup_queue - shutdown a request queue
323 * @q: request queue to shutdown
325 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
326 * put it. All future requests will be failed immediately with -ENODEV.
328 void blk_cleanup_queue(struct request_queue *q)
330 /* mark @q DYING, no new request or merges will be allowed afterwards */
331 mutex_lock(&q->sysfs_lock);
332 blk_set_queue_dying(q);
334 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q);
335 blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
336 blk_queue_flag_set(QUEUE_FLAG_DYING, q);
337 mutex_unlock(&q->sysfs_lock);
340 * Drain all requests queued before DYING marking. Set DEAD flag to
341 * prevent that q->request_fn() gets invoked after draining finished.
347 blk_queue_flag_set(QUEUE_FLAG_DEAD, q);
350 * make sure all in-progress dispatch are completed because
351 * blk_freeze_queue() can only complete all requests, and
352 * dispatch may still be in-progress since we dispatch requests
353 * from more than one contexts.
355 * We rely on driver to deal with the race in case that queue
356 * initialization isn't done.
358 if (queue_is_mq(q) && blk_queue_init_done(q))
359 blk_mq_quiesce_queue(q);
361 /* for synchronous bio-based driver finish in-flight integrity i/o */
362 blk_flush_integrity();
364 /* @q won't process any more request, flush async actions */
365 del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer);
369 * I/O scheduler exit is only safe after the sysfs scheduler attribute
372 WARN_ON_ONCE(q->kobj.state_in_sysfs);
377 blk_mq_free_queue(q);
379 percpu_ref_exit(&q->q_usage_counter);
381 /* @q is and will stay empty, shutdown and put */
384 EXPORT_SYMBOL(blk_cleanup_queue);
386 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
388 return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
390 EXPORT_SYMBOL(blk_alloc_queue);
393 * blk_queue_enter() - try to increase q->q_usage_counter
394 * @q: request queue pointer
395 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT
397 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
399 const bool pm = flags & BLK_MQ_REQ_PREEMPT;
402 bool success = false;
405 if (percpu_ref_tryget_live(&q->q_usage_counter)) {
407 * The code that increments the pm_only counter is
408 * responsible for ensuring that that counter is
409 * globally visible before the queue is unfrozen.
411 if (pm || !blk_queue_pm_only(q)) {
414 percpu_ref_put(&q->q_usage_counter);
422 if (flags & BLK_MQ_REQ_NOWAIT)
426 * read pair of barrier in blk_freeze_queue_start(),
427 * we need to order reading __PERCPU_REF_DEAD flag of
428 * .q_usage_counter and reading .mq_freeze_depth or
429 * queue dying flag, otherwise the following wait may
430 * never return if the two reads are reordered.
434 wait_event(q->mq_freeze_wq,
435 (atomic_read(&q->mq_freeze_depth) == 0 &&
436 (pm || (blk_pm_request_resume(q),
437 !blk_queue_pm_only(q)))) ||
439 if (blk_queue_dying(q))
444 void blk_queue_exit(struct request_queue *q)
446 percpu_ref_put(&q->q_usage_counter);
449 static void blk_queue_usage_counter_release(struct percpu_ref *ref)
451 struct request_queue *q =
452 container_of(ref, struct request_queue, q_usage_counter);
454 wake_up_all(&q->mq_freeze_wq);
457 static void blk_rq_timed_out_timer(struct timer_list *t)
459 struct request_queue *q = from_timer(q, t, timeout);
461 kblockd_schedule_work(&q->timeout_work);
465 * blk_alloc_queue_node - allocate a request queue
466 * @gfp_mask: memory allocation flags
467 * @node_id: NUMA node to allocate memory from
469 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
471 struct request_queue *q;
474 q = kmem_cache_alloc_node(blk_requestq_cachep,
475 gfp_mask | __GFP_ZERO, node_id);
479 INIT_LIST_HEAD(&q->queue_head);
480 q->last_merge = NULL;
482 q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
486 ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
490 q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id);
491 if (!q->backing_dev_info)
494 q->stats = blk_alloc_queue_stats();
498 q->backing_dev_info->ra_pages =
499 (VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
500 q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;
501 q->backing_dev_info->name = "block";
504 timer_setup(&q->backing_dev_info->laptop_mode_wb_timer,
505 laptop_mode_timer_fn, 0);
506 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
507 INIT_WORK(&q->timeout_work, NULL);
508 INIT_LIST_HEAD(&q->icq_list);
509 #ifdef CONFIG_BLK_CGROUP
510 INIT_LIST_HEAD(&q->blkg_list);
513 kobject_init(&q->kobj, &blk_queue_ktype);
515 #ifdef CONFIG_BLK_DEV_IO_TRACE
516 mutex_init(&q->blk_trace_mutex);
518 mutex_init(&q->sysfs_lock);
519 spin_lock_init(&q->queue_lock);
521 init_waitqueue_head(&q->mq_freeze_wq);
524 * Init percpu_ref in atomic mode so that it's faster to shutdown.
525 * See blk_register_queue() for details.
527 if (percpu_ref_init(&q->q_usage_counter,
528 blk_queue_usage_counter_release,
529 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
532 if (blkcg_init_queue(q))
538 percpu_ref_exit(&q->q_usage_counter);
540 blk_free_queue_stats(q->stats);
542 bdi_put(q->backing_dev_info);
544 bioset_exit(&q->bio_split);
546 ida_simple_remove(&blk_queue_ida, q->id);
548 kmem_cache_free(blk_requestq_cachep, q);
551 EXPORT_SYMBOL(blk_alloc_queue_node);
553 bool blk_get_queue(struct request_queue *q)
555 if (likely(!blk_queue_dying(q))) {
562 EXPORT_SYMBOL(blk_get_queue);
565 * blk_get_request - allocate a request
566 * @q: request queue to allocate a request for
567 * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC.
568 * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT.
570 struct request *blk_get_request(struct request_queue *q, unsigned int op,
571 blk_mq_req_flags_t flags)
575 WARN_ON_ONCE(op & REQ_NOWAIT);
576 WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT));
578 req = blk_mq_alloc_request(q, op, flags);
579 if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn)
580 q->mq_ops->initialize_rq_fn(req);
584 EXPORT_SYMBOL(blk_get_request);
586 static void part_round_stats_single(struct request_queue *q, int cpu,
587 struct hd_struct *part, unsigned long now,
588 unsigned int inflight)
591 __part_stat_add(cpu, part, time_in_queue,
592 inflight * (now - part->stamp));
593 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
599 * part_round_stats() - Round off the performance stats on a struct disk_stats.
600 * @q: target block queue
601 * @cpu: cpu number for stats access
602 * @part: target partition
604 * The average IO queue length and utilisation statistics are maintained
605 * by observing the current state of the queue length and the amount of
606 * time it has been in this state for.
608 * Normally, that accounting is done on IO completion, but that can result
609 * in more than a second's worth of IO being accounted for within any one
610 * second, leading to >100% utilisation. To deal with that, we call this
611 * function to do a round-off before returning the results when reading
612 * /proc/diskstats. This accounts immediately for all queue usage up to
613 * the current jiffies and restarts the counters again.
615 void part_round_stats(struct request_queue *q, int cpu, struct hd_struct *part)
617 struct hd_struct *part2 = NULL;
618 unsigned long now = jiffies;
619 unsigned int inflight[2];
622 if (part->stamp != now)
626 part2 = &part_to_disk(part)->part0;
627 if (part2->stamp != now)
634 part_in_flight(q, part, inflight);
637 part_round_stats_single(q, cpu, part2, now, inflight[1]);
639 part_round_stats_single(q, cpu, part, now, inflight[0]);
641 EXPORT_SYMBOL_GPL(part_round_stats);
643 void blk_put_request(struct request *req)
645 blk_mq_free_request(req);
647 EXPORT_SYMBOL(blk_put_request);
649 bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
652 const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
654 if (!ll_back_merge_fn(q, req, bio))
657 trace_block_bio_backmerge(q, req, bio);
659 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
660 blk_rq_set_mixed_merge(req);
662 req->biotail->bi_next = bio;
664 req->__data_len += bio->bi_iter.bi_size;
666 blk_account_io_start(req, false);
670 bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
673 const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
675 if (!ll_front_merge_fn(q, req, bio))
678 trace_block_bio_frontmerge(q, req, bio);
680 if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
681 blk_rq_set_mixed_merge(req);
683 bio->bi_next = req->bio;
686 req->__sector = bio->bi_iter.bi_sector;
687 req->__data_len += bio->bi_iter.bi_size;
689 blk_account_io_start(req, false);
693 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
696 unsigned short segments = blk_rq_nr_discard_segments(req);
698 if (segments >= queue_max_discard_segments(q))
700 if (blk_rq_sectors(req) + bio_sectors(bio) >
701 blk_rq_get_max_sectors(req, blk_rq_pos(req)))
704 req->biotail->bi_next = bio;
706 req->__data_len += bio->bi_iter.bi_size;
707 req->nr_phys_segments = segments + 1;
709 blk_account_io_start(req, false);
712 req_set_nomerge(q, req);
717 * blk_attempt_plug_merge - try to merge with %current's plugged list
718 * @q: request_queue new bio is being queued at
719 * @bio: new bio being queued
720 * @request_count: out parameter for number of traversed plugged requests
721 * @same_queue_rq: pointer to &struct request that gets filled in when
722 * another request associated with @q is found on the plug list
723 * (optional, may be %NULL)
725 * Determine whether @bio being queued on @q can be merged with a request
726 * on %current's plugged list. Returns %true if merge was successful,
729 * Plugging coalesces IOs from the same issuer for the same purpose without
730 * going through @q->queue_lock. As such it's more of an issuing mechanism
731 * than scheduling, and the request, while may have elvpriv data, is not
732 * added on the elevator at this point. In addition, we don't have
733 * reliable access to the elevator outside queue lock. Only check basic
734 * merging parameters without querying the elevator.
736 * Caller must ensure !blk_queue_nomerges(q) beforehand.
738 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
739 struct request **same_queue_rq)
741 struct blk_plug *plug;
743 struct list_head *plug_list;
745 plug = current->plug;
749 plug_list = &plug->mq_list;
751 list_for_each_entry_reverse(rq, plug_list, queuelist) {
754 if (rq->q == q && same_queue_rq) {
756 * Only blk-mq multiple hardware queues case checks the
757 * rq in the same queue, there should be only one such
763 if (rq->q != q || !blk_rq_merge_ok(rq, bio))
766 switch (blk_try_merge(rq, bio)) {
767 case ELEVATOR_BACK_MERGE:
768 merged = bio_attempt_back_merge(q, rq, bio);
770 case ELEVATOR_FRONT_MERGE:
771 merged = bio_attempt_front_merge(q, rq, bio);
773 case ELEVATOR_DISCARD_MERGE:
774 merged = bio_attempt_discard_merge(q, rq, bio);
787 void blk_init_request_from_bio(struct request *req, struct bio *bio)
789 if (bio->bi_opf & REQ_RAHEAD)
790 req->cmd_flags |= REQ_FAILFAST_MASK;
792 req->__sector = bio->bi_iter.bi_sector;
793 req->ioprio = bio_prio(bio);
794 req->write_hint = bio->bi_write_hint;
795 blk_rq_bio_prep(req->q, req, bio);
797 EXPORT_SYMBOL_GPL(blk_init_request_from_bio);
799 static void handle_bad_sector(struct bio *bio, sector_t maxsector)
801 char b[BDEVNAME_SIZE];
803 printk(KERN_INFO "attempt to access beyond end of device\n");
804 printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n",
805 bio_devname(bio, b), bio->bi_opf,
806 (unsigned long long)bio_end_sector(bio),
807 (long long)maxsector);
810 #ifdef CONFIG_FAIL_MAKE_REQUEST
812 static DECLARE_FAULT_ATTR(fail_make_request);
814 static int __init setup_fail_make_request(char *str)
816 return setup_fault_attr(&fail_make_request, str);
818 __setup("fail_make_request=", setup_fail_make_request);
820 static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
822 return part->make_it_fail && should_fail(&fail_make_request, bytes);
825 static int __init fail_make_request_debugfs(void)
827 struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
828 NULL, &fail_make_request);
830 return PTR_ERR_OR_ZERO(dir);
833 late_initcall(fail_make_request_debugfs);
835 #else /* CONFIG_FAIL_MAKE_REQUEST */
837 static inline bool should_fail_request(struct hd_struct *part,
843 #endif /* CONFIG_FAIL_MAKE_REQUEST */
845 static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part)
847 const int op = bio_op(bio);
849 if (part->policy && op_is_write(op)) {
850 char b[BDEVNAME_SIZE];
852 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
856 "generic_make_request: Trying to write "
857 "to read-only block-device %s (partno %d)\n",
858 bio_devname(bio, b), part->partno);
859 /* Older lvm-tools actually trigger this */
866 static noinline int should_fail_bio(struct bio *bio)
868 if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size))
872 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO);
875 * Check whether this bio extends beyond the end of the device or partition.
876 * This may well happen - the kernel calls bread() without checking the size of
877 * the device, e.g., when mounting a file system.
879 static inline int bio_check_eod(struct bio *bio, sector_t maxsector)
881 unsigned int nr_sectors = bio_sectors(bio);
883 if (nr_sectors && maxsector &&
884 (nr_sectors > maxsector ||
885 bio->bi_iter.bi_sector > maxsector - nr_sectors)) {
886 handle_bad_sector(bio, maxsector);
893 * Remap block n of partition p to block n+start(p) of the disk.
895 static inline int blk_partition_remap(struct bio *bio)
901 p = __disk_get_part(bio->bi_disk, bio->bi_partno);
904 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size)))
906 if (unlikely(bio_check_ro(bio, p)))
910 * Zone reset does not include bi_size so bio_sectors() is always 0.
911 * Include a test for the reset op code and perform the remap if needed.
913 if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) {
914 if (bio_check_eod(bio, part_nr_sects_read(p)))
916 bio->bi_iter.bi_sector += p->start_sect;
917 trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p),
918 bio->bi_iter.bi_sector - p->start_sect);
927 static noinline_for_stack bool
928 generic_make_request_checks(struct bio *bio)
930 struct request_queue *q;
931 int nr_sectors = bio_sectors(bio);
932 blk_status_t status = BLK_STS_IOERR;
933 char b[BDEVNAME_SIZE];
937 q = bio->bi_disk->queue;
940 "generic_make_request: Trying to access "
941 "nonexistent block-device %s (%Lu)\n",
942 bio_devname(bio, b), (long long)bio->bi_iter.bi_sector);
947 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
948 * if queue is not a request based queue.
950 if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q))
953 if (should_fail_bio(bio))
956 if (bio->bi_partno) {
957 if (unlikely(blk_partition_remap(bio)))
960 if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0)))
962 if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk))))
967 * Filter flush bio's early so that make_request based
968 * drivers without flush support don't have to worry
971 if (op_is_flush(bio->bi_opf) &&
972 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
973 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
980 switch (bio_op(bio)) {
982 if (!blk_queue_discard(q))
985 case REQ_OP_SECURE_ERASE:
986 if (!blk_queue_secure_erase(q))
989 case REQ_OP_WRITE_SAME:
990 if (!q->limits.max_write_same_sectors)
993 case REQ_OP_ZONE_RESET:
994 if (!blk_queue_is_zoned(q))
997 case REQ_OP_WRITE_ZEROES:
998 if (!q->limits.max_write_zeroes_sectors)
1006 * Various block parts want %current->io_context and lazy ioc
1007 * allocation ends up trading a lot of pain for a small amount of
1008 * memory. Just allocate it upfront. This may fail and block
1009 * layer knows how to live with it.
1011 create_io_context(GFP_ATOMIC, q->node);
1013 if (!blkcg_bio_issue_check(q, bio))
1016 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
1017 trace_block_bio_queue(q, bio);
1018 /* Now that enqueuing has been traced, we need to trace
1019 * completion as well.
1021 bio_set_flag(bio, BIO_TRACE_COMPLETION);
1026 status = BLK_STS_NOTSUPP;
1028 bio->bi_status = status;
1034 * generic_make_request - hand a buffer to its device driver for I/O
1035 * @bio: The bio describing the location in memory and on the device.
1037 * generic_make_request() is used to make I/O requests of block
1038 * devices. It is passed a &struct bio, which describes the I/O that needs
1041 * generic_make_request() does not return any status. The
1042 * success/failure status of the request, along with notification of
1043 * completion, is delivered asynchronously through the bio->bi_end_io
1044 * function described (one day) else where.
1046 * The caller of generic_make_request must make sure that bi_io_vec
1047 * are set to describe the memory buffer, and that bi_dev and bi_sector are
1048 * set to describe the device address, and the
1049 * bi_end_io and optionally bi_private are set to describe how
1050 * completion notification should be signaled.
1052 * generic_make_request and the drivers it calls may use bi_next if this
1053 * bio happens to be merged with someone else, and may resubmit the bio to
1054 * a lower device by calling into generic_make_request recursively, which
1055 * means the bio should NOT be touched after the call to ->make_request_fn.
1057 blk_qc_t generic_make_request(struct bio *bio)
1060 * bio_list_on_stack[0] contains bios submitted by the current
1062 * bio_list_on_stack[1] contains bios that were submitted before
1063 * the current make_request_fn, but that haven't been processed
1066 struct bio_list bio_list_on_stack[2];
1067 blk_mq_req_flags_t flags = 0;
1068 struct request_queue *q = bio->bi_disk->queue;
1069 blk_qc_t ret = BLK_QC_T_NONE;
1071 if (bio->bi_opf & REQ_NOWAIT)
1072 flags = BLK_MQ_REQ_NOWAIT;
1073 if (bio_flagged(bio, BIO_QUEUE_ENTERED))
1074 blk_queue_enter_live(q);
1075 else if (blk_queue_enter(q, flags) < 0) {
1076 if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT))
1077 bio_wouldblock_error(bio);
1083 if (!generic_make_request_checks(bio))
1087 * We only want one ->make_request_fn to be active at a time, else
1088 * stack usage with stacked devices could be a problem. So use
1089 * current->bio_list to keep a list of requests submited by a
1090 * make_request_fn function. current->bio_list is also used as a
1091 * flag to say if generic_make_request is currently active in this
1092 * task or not. If it is NULL, then no make_request is active. If
1093 * it is non-NULL, then a make_request is active, and new requests
1094 * should be added at the tail
1096 if (current->bio_list) {
1097 bio_list_add(¤t->bio_list[0], bio);
1101 /* following loop may be a bit non-obvious, and so deserves some
1103 * Before entering the loop, bio->bi_next is NULL (as all callers
1104 * ensure that) so we have a list with a single bio.
1105 * We pretend that we have just taken it off a longer list, so
1106 * we assign bio_list to a pointer to the bio_list_on_stack,
1107 * thus initialising the bio_list of new bios to be
1108 * added. ->make_request() may indeed add some more bios
1109 * through a recursive call to generic_make_request. If it
1110 * did, we find a non-NULL value in bio_list and re-enter the loop
1111 * from the top. In this case we really did just take the bio
1112 * of the top of the list (no pretending) and so remove it from
1113 * bio_list, and call into ->make_request() again.
1115 BUG_ON(bio->bi_next);
1116 bio_list_init(&bio_list_on_stack[0]);
1117 current->bio_list = bio_list_on_stack;
1119 bool enter_succeeded = true;
1121 if (unlikely(q != bio->bi_disk->queue)) {
1124 q = bio->bi_disk->queue;
1126 if (bio->bi_opf & REQ_NOWAIT)
1127 flags = BLK_MQ_REQ_NOWAIT;
1128 if (blk_queue_enter(q, flags) < 0) {
1129 enter_succeeded = false;
1134 if (enter_succeeded) {
1135 struct bio_list lower, same;
1137 /* Create a fresh bio_list for all subordinate requests */
1138 bio_list_on_stack[1] = bio_list_on_stack[0];
1139 bio_list_init(&bio_list_on_stack[0]);
1140 ret = q->make_request_fn(q, bio);
1142 /* sort new bios into those for a lower level
1143 * and those for the same level
1145 bio_list_init(&lower);
1146 bio_list_init(&same);
1147 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
1148 if (q == bio->bi_disk->queue)
1149 bio_list_add(&same, bio);
1151 bio_list_add(&lower, bio);
1152 /* now assemble so we handle the lowest level first */
1153 bio_list_merge(&bio_list_on_stack[0], &lower);
1154 bio_list_merge(&bio_list_on_stack[0], &same);
1155 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
1157 if (unlikely(!blk_queue_dying(q) &&
1158 (bio->bi_opf & REQ_NOWAIT)))
1159 bio_wouldblock_error(bio);
1163 bio = bio_list_pop(&bio_list_on_stack[0]);
1165 current->bio_list = NULL; /* deactivate */
1172 EXPORT_SYMBOL(generic_make_request);
1175 * direct_make_request - hand a buffer directly to its device driver for I/O
1176 * @bio: The bio describing the location in memory and on the device.
1178 * This function behaves like generic_make_request(), but does not protect
1179 * against recursion. Must only be used if the called driver is known
1180 * to not call generic_make_request (or direct_make_request) again from
1181 * its make_request function. (Calling direct_make_request again from
1182 * a workqueue is perfectly fine as that doesn't recurse).
1184 blk_qc_t direct_make_request(struct bio *bio)
1186 struct request_queue *q = bio->bi_disk->queue;
1187 bool nowait = bio->bi_opf & REQ_NOWAIT;
1190 if (!generic_make_request_checks(bio))
1191 return BLK_QC_T_NONE;
1193 if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) {
1194 if (nowait && !blk_queue_dying(q))
1195 bio->bi_status = BLK_STS_AGAIN;
1197 bio->bi_status = BLK_STS_IOERR;
1199 return BLK_QC_T_NONE;
1202 ret = q->make_request_fn(q, bio);
1206 EXPORT_SYMBOL_GPL(direct_make_request);
1209 * submit_bio - submit a bio to the block device layer for I/O
1210 * @bio: The &struct bio which describes the I/O
1212 * submit_bio() is very similar in purpose to generic_make_request(), and
1213 * uses that function to do most of the work. Both are fairly rough
1214 * interfaces; @bio must be presetup and ready for I/O.
1217 blk_qc_t submit_bio(struct bio *bio)
1220 * If it's a regular read/write or a barrier with data attached,
1221 * go through the normal accounting stuff before submission.
1223 if (bio_has_data(bio)) {
1226 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
1227 count = queue_logical_block_size(bio->bi_disk->queue) >> 9;
1229 count = bio_sectors(bio);
1231 if (op_is_write(bio_op(bio))) {
1232 count_vm_events(PGPGOUT, count);
1234 task_io_account_read(bio->bi_iter.bi_size);
1235 count_vm_events(PGPGIN, count);
1238 if (unlikely(block_dump)) {
1239 char b[BDEVNAME_SIZE];
1240 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
1241 current->comm, task_pid_nr(current),
1242 op_is_write(bio_op(bio)) ? "WRITE" : "READ",
1243 (unsigned long long)bio->bi_iter.bi_sector,
1244 bio_devname(bio, b), count);
1248 return generic_make_request(bio);
1250 EXPORT_SYMBOL(submit_bio);
1253 * blk_poll - poll for IO completions
1255 * @cookie: cookie passed back at IO submission time
1256 * @spin: whether to spin for completions
1259 * Poll for completions on the passed in queue. Returns number of
1260 * completed entries found. If @spin is true, then blk_poll will continue
1261 * looping until at least one completion is found, unless the task is
1262 * otherwise marked running (or we need to reschedule).
1264 int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
1266 if (!q->poll_fn || !blk_qc_t_valid(cookie))
1270 blk_flush_plug_list(current->plug, false);
1271 return q->poll_fn(q, cookie, spin);
1273 EXPORT_SYMBOL_GPL(blk_poll);
1276 * blk_cloned_rq_check_limits - Helper function to check a cloned request
1277 * for new the queue limits
1279 * @rq: the request being checked
1282 * @rq may have been made based on weaker limitations of upper-level queues
1283 * in request stacking drivers, and it may violate the limitation of @q.
1284 * Since the block layer and the underlying device driver trust @rq
1285 * after it is inserted to @q, it should be checked against @q before
1286 * the insertion using this generic function.
1288 * Request stacking drivers like request-based dm may change the queue
1289 * limits when retrying requests on other queues. Those requests need
1290 * to be checked against the new queue limits again during dispatch.
1292 static int blk_cloned_rq_check_limits(struct request_queue *q,
1295 if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) {
1296 printk(KERN_ERR "%s: over max size limit.\n", __func__);
1301 * queue's settings related to segment counting like q->bounce_pfn
1302 * may differ from that of other stacking queues.
1303 * Recalculate it to check the request correctly on this queue's
1306 blk_recalc_rq_segments(rq);
1307 if (rq->nr_phys_segments > queue_max_segments(q)) {
1308 printk(KERN_ERR "%s: over max segments limit.\n", __func__);
1316 * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1317 * @q: the queue to submit the request
1318 * @rq: the request being queued
1320 blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq)
1322 if (blk_cloned_rq_check_limits(q, rq))
1323 return BLK_STS_IOERR;
1326 should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
1327 return BLK_STS_IOERR;
1329 if (blk_queue_io_stat(q))
1330 blk_account_io_start(rq, true);
1333 * Since we have a scheduler attached on the top device,
1334 * bypass a potential scheduler on the bottom device for
1337 return blk_mq_request_issue_directly(rq);
1339 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
1342 * blk_rq_err_bytes - determine number of bytes till the next failure boundary
1343 * @rq: request to examine
1346 * A request could be merge of IOs which require different failure
1347 * handling. This function determines the number of bytes which
1348 * can be failed from the beginning of the request without
1349 * crossing into area which need to be retried further.
1352 * The number of bytes to fail.
1354 unsigned int blk_rq_err_bytes(const struct request *rq)
1356 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
1357 unsigned int bytes = 0;
1360 if (!(rq->rq_flags & RQF_MIXED_MERGE))
1361 return blk_rq_bytes(rq);
1364 * Currently the only 'mixing' which can happen is between
1365 * different fastfail types. We can safely fail portions
1366 * which have all the failfast bits that the first one has -
1367 * the ones which are at least as eager to fail as the first
1370 for (bio = rq->bio; bio; bio = bio->bi_next) {
1371 if ((bio->bi_opf & ff) != ff)
1373 bytes += bio->bi_iter.bi_size;
1376 /* this could lead to infinite loop */
1377 BUG_ON(blk_rq_bytes(rq) && !bytes);
1380 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
1382 void blk_account_io_completion(struct request *req, unsigned int bytes)
1384 if (blk_do_io_stat(req)) {
1385 const int sgrp = op_stat_group(req_op(req));
1386 struct hd_struct *part;
1389 cpu = part_stat_lock();
1391 part_stat_add(cpu, part, sectors[sgrp], bytes >> 9);
1396 void blk_account_io_done(struct request *req, u64 now)
1399 * Account IO completion. flush_rq isn't accounted as a
1400 * normal IO on queueing nor completion. Accounting the
1401 * containing request is enough.
1403 if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) {
1404 const int sgrp = op_stat_group(req_op(req));
1405 struct hd_struct *part;
1408 cpu = part_stat_lock();
1411 part_stat_inc(cpu, part, ios[sgrp]);
1412 part_stat_add(cpu, part, nsecs[sgrp], now - req->start_time_ns);
1413 part_round_stats(req->q, cpu, part);
1414 part_dec_in_flight(req->q, part, rq_data_dir(req));
1416 hd_struct_put(part);
1421 void blk_account_io_start(struct request *rq, bool new_io)
1423 struct hd_struct *part;
1424 int rw = rq_data_dir(rq);
1427 if (!blk_do_io_stat(rq))
1430 cpu = part_stat_lock();
1434 part_stat_inc(cpu, part, merges[rw]);
1436 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
1437 if (!hd_struct_try_get(part)) {
1439 * The partition is already being removed,
1440 * the request will be accounted on the disk only
1442 * We take a reference on disk->part0 although that
1443 * partition will never be deleted, so we can treat
1444 * it as any other partition.
1446 part = &rq->rq_disk->part0;
1447 hd_struct_get(part);
1449 part_round_stats(rq->q, cpu, part);
1450 part_inc_in_flight(rq->q, part, rw);
1458 * Steal bios from a request and add them to a bio list.
1459 * The request must not have been partially completed before.
1461 void blk_steal_bios(struct bio_list *list, struct request *rq)
1465 list->tail->bi_next = rq->bio;
1467 list->head = rq->bio;
1468 list->tail = rq->biotail;
1476 EXPORT_SYMBOL_GPL(blk_steal_bios);
1479 * blk_update_request - Special helper function for request stacking drivers
1480 * @req: the request being processed
1481 * @error: block status code
1482 * @nr_bytes: number of bytes to complete @req
1485 * Ends I/O on a number of bytes attached to @req, but doesn't complete
1486 * the request structure even if @req doesn't have leftover.
1487 * If @req has leftover, sets it up for the next range of segments.
1489 * This special helper function is only for request stacking drivers
1490 * (e.g. request-based dm) so that they can handle partial completion.
1491 * Actual device drivers should use blk_end_request instead.
1493 * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
1494 * %false return from this function.
1497 * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both
1498 * blk_rq_bytes() and in blk_update_request().
1501 * %false - this request doesn't have any more data
1502 * %true - this request has more data
1504 bool blk_update_request(struct request *req, blk_status_t error,
1505 unsigned int nr_bytes)
1509 trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes);
1514 if (unlikely(error && !blk_rq_is_passthrough(req) &&
1515 !(req->rq_flags & RQF_QUIET)))
1516 print_req_error(req, error);
1518 blk_account_io_completion(req, nr_bytes);
1522 struct bio *bio = req->bio;
1523 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
1525 if (bio_bytes == bio->bi_iter.bi_size)
1526 req->bio = bio->bi_next;
1528 /* Completion has already been traced */
1529 bio_clear_flag(bio, BIO_TRACE_COMPLETION);
1530 req_bio_endio(req, bio, bio_bytes, error);
1532 total_bytes += bio_bytes;
1533 nr_bytes -= bio_bytes;
1544 * Reset counters so that the request stacking driver
1545 * can find how many bytes remain in the request
1548 req->__data_len = 0;
1552 req->__data_len -= total_bytes;
1554 /* update sector only for requests with clear definition of sector */
1555 if (!blk_rq_is_passthrough(req))
1556 req->__sector += total_bytes >> 9;
1558 /* mixed attributes always follow the first bio */
1559 if (req->rq_flags & RQF_MIXED_MERGE) {
1560 req->cmd_flags &= ~REQ_FAILFAST_MASK;
1561 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK;
1564 if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) {
1566 * If total number of sectors is less than the first segment
1567 * size, something has gone terribly wrong.
1569 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
1570 blk_dump_rq_flags(req, "request botched");
1571 req->__data_len = blk_rq_cur_bytes(req);
1574 /* recalculate the number of segments */
1575 blk_recalc_rq_segments(req);
1580 EXPORT_SYMBOL_GPL(blk_update_request);
1582 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
1585 if (bio_has_data(bio))
1586 rq->nr_phys_segments = bio_phys_segments(q, bio);
1587 else if (bio_op(bio) == REQ_OP_DISCARD)
1588 rq->nr_phys_segments = 1;
1590 rq->__data_len = bio->bi_iter.bi_size;
1591 rq->bio = rq->biotail = bio;
1594 rq->rq_disk = bio->bi_disk;
1597 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1599 * rq_flush_dcache_pages - Helper function to flush all pages in a request
1600 * @rq: the request to be flushed
1603 * Flush all pages in @rq.
1605 void rq_flush_dcache_pages(struct request *rq)
1607 struct req_iterator iter;
1608 struct bio_vec bvec;
1610 rq_for_each_segment(bvec, rq, iter)
1611 flush_dcache_page(bvec.bv_page);
1613 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
1617 * blk_lld_busy - Check if underlying low-level drivers of a device are busy
1618 * @q : the queue of the device being checked
1621 * Check if underlying low-level drivers of a device are busy.
1622 * If the drivers want to export their busy state, they must set own
1623 * exporting function using blk_queue_lld_busy() first.
1625 * Basically, this function is used only by request stacking drivers
1626 * to stop dispatching requests to underlying devices when underlying
1627 * devices are busy. This behavior helps more I/O merging on the queue
1628 * of the request stacking driver and prevents I/O throughput regression
1629 * on burst I/O load.
1632 * 0 - Not busy (The request stacking driver should dispatch request)
1633 * 1 - Busy (The request stacking driver should stop dispatching request)
1635 int blk_lld_busy(struct request_queue *q)
1637 if (queue_is_mq(q) && q->mq_ops->busy)
1638 return q->mq_ops->busy(q);
1642 EXPORT_SYMBOL_GPL(blk_lld_busy);
1645 * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
1646 * @rq: the clone request to be cleaned up
1649 * Free all bios in @rq for a cloned request.
1651 void blk_rq_unprep_clone(struct request *rq)
1655 while ((bio = rq->bio) != NULL) {
1656 rq->bio = bio->bi_next;
1661 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
1664 * Copy attributes of the original request to the clone request.
1665 * The actual data parts (e.g. ->cmd, ->sense) are not copied.
1667 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
1669 dst->__sector = blk_rq_pos(src);
1670 dst->__data_len = blk_rq_bytes(src);
1671 if (src->rq_flags & RQF_SPECIAL_PAYLOAD) {
1672 dst->rq_flags |= RQF_SPECIAL_PAYLOAD;
1673 dst->special_vec = src->special_vec;
1675 dst->nr_phys_segments = src->nr_phys_segments;
1676 dst->ioprio = src->ioprio;
1677 dst->extra_len = src->extra_len;
1681 * blk_rq_prep_clone - Helper function to setup clone request
1682 * @rq: the request to be setup
1683 * @rq_src: original request to be cloned
1684 * @bs: bio_set that bios for clone are allocated from
1685 * @gfp_mask: memory allocation mask for bio
1686 * @bio_ctr: setup function to be called for each clone bio.
1687 * Returns %0 for success, non %0 for failure.
1688 * @data: private data to be passed to @bio_ctr
1691 * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
1692 * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
1693 * are not copied, and copying such parts is the caller's responsibility.
1694 * Also, pages which the original bios are pointing to are not copied
1695 * and the cloned bios just point same pages.
1696 * So cloned bios must be completed before original bios, which means
1697 * the caller must complete @rq before @rq_src.
1699 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
1700 struct bio_set *bs, gfp_t gfp_mask,
1701 int (*bio_ctr)(struct bio *, struct bio *, void *),
1704 struct bio *bio, *bio_src;
1709 __rq_for_each_bio(bio_src, rq_src) {
1710 bio = bio_clone_fast(bio_src, gfp_mask, bs);
1714 if (bio_ctr && bio_ctr(bio, bio_src, data))
1718 rq->biotail->bi_next = bio;
1721 rq->bio = rq->biotail = bio;
1724 __blk_rq_prep_clone(rq, rq_src);
1731 blk_rq_unprep_clone(rq);
1735 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
1737 int kblockd_schedule_work(struct work_struct *work)
1739 return queue_work(kblockd_workqueue, work);
1741 EXPORT_SYMBOL(kblockd_schedule_work);
1743 int kblockd_schedule_work_on(int cpu, struct work_struct *work)
1745 return queue_work_on(cpu, kblockd_workqueue, work);
1747 EXPORT_SYMBOL(kblockd_schedule_work_on);
1749 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
1750 unsigned long delay)
1752 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
1754 EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
1757 * blk_start_plug - initialize blk_plug and track it inside the task_struct
1758 * @plug: The &struct blk_plug that needs to be initialized
1761 * Tracking blk_plug inside the task_struct will help with auto-flushing the
1762 * pending I/O should the task end up blocking between blk_start_plug() and
1763 * blk_finish_plug(). This is important from a performance perspective, but
1764 * also ensures that we don't deadlock. For instance, if the task is blocking
1765 * for a memory allocation, memory reclaim could end up wanting to free a
1766 * page belonging to that request that is currently residing in our private
1767 * plug. By flushing the pending I/O when the process goes to sleep, we avoid
1768 * this kind of deadlock.
1770 void blk_start_plug(struct blk_plug *plug)
1772 struct task_struct *tsk = current;
1775 * If this is a nested plug, don't actually assign it.
1780 INIT_LIST_HEAD(&plug->mq_list);
1781 INIT_LIST_HEAD(&plug->cb_list);
1783 plug->multiple_queues = false;
1786 * Store ordering should not be needed here, since a potential
1787 * preempt will imply a full memory barrier
1791 EXPORT_SYMBOL(blk_start_plug);
1793 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
1795 LIST_HEAD(callbacks);
1797 while (!list_empty(&plug->cb_list)) {
1798 list_splice_init(&plug->cb_list, &callbacks);
1800 while (!list_empty(&callbacks)) {
1801 struct blk_plug_cb *cb = list_first_entry(&callbacks,
1804 list_del(&cb->list);
1805 cb->callback(cb, from_schedule);
1810 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
1813 struct blk_plug *plug = current->plug;
1814 struct blk_plug_cb *cb;
1819 list_for_each_entry(cb, &plug->cb_list, list)
1820 if (cb->callback == unplug && cb->data == data)
1823 /* Not currently on the callback list */
1824 BUG_ON(size < sizeof(*cb));
1825 cb = kzalloc(size, GFP_ATOMIC);
1828 cb->callback = unplug;
1829 list_add(&cb->list, &plug->cb_list);
1833 EXPORT_SYMBOL(blk_check_plugged);
1835 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1837 flush_plug_callbacks(plug, from_schedule);
1839 if (!list_empty(&plug->mq_list))
1840 blk_mq_flush_plug_list(plug, from_schedule);
1843 void blk_finish_plug(struct blk_plug *plug)
1845 if (plug != current->plug)
1847 blk_flush_plug_list(plug, false);
1849 current->plug = NULL;
1851 EXPORT_SYMBOL(blk_finish_plug);
1853 int __init blk_dev_init(void)
1855 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS));
1856 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
1857 FIELD_SIZEOF(struct request, cmd_flags));
1858 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
1859 FIELD_SIZEOF(struct bio, bi_opf));
1861 /* used for unplugging and affects IO latency/throughput - HIGHPRI */
1862 kblockd_workqueue = alloc_workqueue("kblockd",
1863 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1864 if (!kblockd_workqueue)
1865 panic("Failed to create kblockd\n");
1867 blk_requestq_cachep = kmem_cache_create("request_queue",
1868 sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
1870 #ifdef CONFIG_DEBUG_FS
1871 blk_debugfs_root = debugfs_create_dir("block", NULL);