2 * Block multiqueue core code
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/backing-dev.h>
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/kmemleak.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/workqueue.h>
17 #include <linux/smp.h>
18 #include <linux/llist.h>
19 #include <linux/list_sort.h>
20 #include <linux/cpu.h>
21 #include <linux/cache.h>
22 #include <linux/sched/sysctl.h>
23 #include <linux/delay.h>
24 #include <linux/crash_dump.h>
25 #include <linux/prefetch.h>
27 #include <trace/events/block.h>
29 #include <linux/blk-mq.h>
32 #include "blk-mq-tag.h"
35 #include "blk-mq-sched.h"
37 static DEFINE_MUTEX(all_q_mutex
);
38 static LIST_HEAD(all_q_list
);
41 * Check if any of the ctx's have pending work in this hardware queue
43 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
45 return sbitmap_any_bit_set(&hctx
->ctx_map
) ||
46 !list_empty_careful(&hctx
->dispatch
) ||
47 blk_mq_sched_has_work(hctx
);
51 * Mark this ctx as having pending work in this hardware queue
53 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
54 struct blk_mq_ctx
*ctx
)
56 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
57 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
60 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
61 struct blk_mq_ctx
*ctx
)
63 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
66 void blk_mq_freeze_queue_start(struct request_queue
*q
)
70 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
71 if (freeze_depth
== 1) {
72 percpu_ref_kill(&q
->q_usage_counter
);
73 blk_mq_run_hw_queues(q
, false);
76 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start
);
78 static void blk_mq_freeze_queue_wait(struct request_queue
*q
)
80 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
84 * Guarantee no request is in use, so we can change any data structure of
85 * the queue afterward.
87 void blk_freeze_queue(struct request_queue
*q
)
90 * In the !blk_mq case we are only calling this to kill the
91 * q_usage_counter, otherwise this increases the freeze depth
92 * and waits for it to return to zero. For this reason there is
93 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
94 * exported to drivers as the only user for unfreeze is blk_mq.
96 blk_mq_freeze_queue_start(q
);
97 blk_mq_freeze_queue_wait(q
);
100 void blk_mq_freeze_queue(struct request_queue
*q
)
103 * ...just an alias to keep freeze and unfreeze actions balanced
104 * in the blk_mq_* namespace
108 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
110 void blk_mq_unfreeze_queue(struct request_queue
*q
)
114 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
115 WARN_ON_ONCE(freeze_depth
< 0);
117 percpu_ref_reinit(&q
->q_usage_counter
);
118 wake_up_all(&q
->mq_freeze_wq
);
121 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
124 * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
127 * Note: this function does not prevent that the struct request end_io()
128 * callback function is invoked. Additionally, it is not prevented that
129 * new queue_rq() calls occur unless the queue has been stopped first.
131 void blk_mq_quiesce_queue(struct request_queue
*q
)
133 struct blk_mq_hw_ctx
*hctx
;
137 blk_mq_stop_hw_queues(q
);
139 queue_for_each_hw_ctx(q
, hctx
, i
) {
140 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
141 synchronize_srcu(&hctx
->queue_rq_srcu
);
148 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
150 void blk_mq_wake_waiters(struct request_queue
*q
)
152 struct blk_mq_hw_ctx
*hctx
;
155 queue_for_each_hw_ctx(q
, hctx
, i
)
156 if (blk_mq_hw_queue_mapped(hctx
))
157 blk_mq_tag_wakeup_all(hctx
->tags
, true);
160 * If we are called because the queue has now been marked as
161 * dying, we need to ensure that processes currently waiting on
162 * the queue are notified as well.
164 wake_up_all(&q
->mq_freeze_wq
);
167 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
169 return blk_mq_has_free_tags(hctx
->tags
);
171 EXPORT_SYMBOL(blk_mq_can_queue
);
173 void blk_mq_rq_ctx_init(struct request_queue
*q
, struct blk_mq_ctx
*ctx
,
174 struct request
*rq
, unsigned int op
)
176 INIT_LIST_HEAD(&rq
->queuelist
);
177 /* csd/requeue_work/fifo_time is initialized before use */
181 if (blk_queue_io_stat(q
))
182 rq
->rq_flags
|= RQF_IO_STAT
;
183 /* do not touch atomic flags, it needs atomic ops against the timer */
185 INIT_HLIST_NODE(&rq
->hash
);
186 RB_CLEAR_NODE(&rq
->rb_node
);
189 rq
->start_time
= jiffies
;
190 #ifdef CONFIG_BLK_CGROUP
192 set_start_time_ns(rq
);
193 rq
->io_start_time_ns
= 0;
195 rq
->nr_phys_segments
= 0;
196 #if defined(CONFIG_BLK_DEV_INTEGRITY)
197 rq
->nr_integrity_segments
= 0;
200 /* tag was already set */
210 INIT_LIST_HEAD(&rq
->timeout_list
);
214 rq
->end_io_data
= NULL
;
217 ctx
->rq_dispatched
[op_is_sync(op
)]++;
219 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init
);
221 struct request
*__blk_mq_alloc_request(struct blk_mq_alloc_data
*data
,
227 tag
= blk_mq_get_tag(data
);
228 if (tag
!= BLK_MQ_TAG_FAIL
) {
229 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
231 rq
= tags
->static_rqs
[tag
];
233 if (blk_mq_tag_busy(data
->hctx
)) {
234 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
235 atomic_inc(&data
->hctx
->nr_active
);
238 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
240 rq
->internal_tag
= tag
;
243 rq
->internal_tag
= -1;
246 blk_mq_rq_ctx_init(data
->q
, data
->ctx
, rq
, op
);
252 EXPORT_SYMBOL_GPL(__blk_mq_alloc_request
);
254 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
257 struct blk_mq_alloc_data alloc_data
;
261 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
265 rq
= blk_mq_sched_get_request(q
, NULL
, rw
, &alloc_data
);
267 blk_mq_put_ctx(alloc_data
.ctx
);
271 return ERR_PTR(-EWOULDBLOCK
);
274 rq
->__sector
= (sector_t
) -1;
275 rq
->bio
= rq
->biotail
= NULL
;
278 EXPORT_SYMBOL(blk_mq_alloc_request
);
280 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
, int rw
,
281 unsigned int flags
, unsigned int hctx_idx
)
283 struct blk_mq_hw_ctx
*hctx
;
284 struct blk_mq_ctx
*ctx
;
286 struct blk_mq_alloc_data alloc_data
;
290 * If the tag allocator sleeps we could get an allocation for a
291 * different hardware context. No need to complicate the low level
292 * allocator for this for the rare use case of a command tied to
295 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
296 return ERR_PTR(-EINVAL
);
298 if (hctx_idx
>= q
->nr_hw_queues
)
299 return ERR_PTR(-EIO
);
301 ret
= blk_queue_enter(q
, true);
306 * Check if the hardware context is actually mapped to anything.
307 * If not tell the caller that it should skip this queue.
309 hctx
= q
->queue_hw_ctx
[hctx_idx
];
310 if (!blk_mq_hw_queue_mapped(hctx
)) {
314 ctx
= __blk_mq_get_ctx(q
, cpumask_first(hctx
->cpumask
));
316 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
317 rq
= __blk_mq_alloc_request(&alloc_data
, rw
);
329 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
331 void __blk_mq_finish_request(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
334 const int sched_tag
= rq
->internal_tag
;
335 struct request_queue
*q
= rq
->q
;
337 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
338 atomic_dec(&hctx
->nr_active
);
340 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
343 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
344 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
346 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
348 blk_mq_sched_completed_request(hctx
, rq
);
352 static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx
*hctx
,
355 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
357 ctx
->rq_completed
[rq_is_sync(rq
)]++;
358 __blk_mq_finish_request(hctx
, ctx
, rq
);
361 void blk_mq_finish_request(struct request
*rq
)
363 blk_mq_finish_hctx_request(blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
), rq
);
366 void blk_mq_free_request(struct request
*rq
)
368 blk_mq_sched_put_request(rq
);
370 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
372 inline void __blk_mq_end_request(struct request
*rq
, int error
)
374 blk_account_io_done(rq
);
377 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
378 rq
->end_io(rq
, error
);
380 if (unlikely(blk_bidi_rq(rq
)))
381 blk_mq_free_request(rq
->next_rq
);
382 blk_mq_free_request(rq
);
385 EXPORT_SYMBOL(__blk_mq_end_request
);
387 void blk_mq_end_request(struct request
*rq
, int error
)
389 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
391 __blk_mq_end_request(rq
, error
);
393 EXPORT_SYMBOL(blk_mq_end_request
);
395 static void __blk_mq_complete_request_remote(void *data
)
397 struct request
*rq
= data
;
399 rq
->q
->softirq_done_fn(rq
);
402 static void blk_mq_ipi_complete_request(struct request
*rq
)
404 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
408 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
409 rq
->q
->softirq_done_fn(rq
);
414 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
415 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
417 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
418 rq
->csd
.func
= __blk_mq_complete_request_remote
;
421 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
423 rq
->q
->softirq_done_fn(rq
);
428 static void blk_mq_stat_add(struct request
*rq
)
430 if (rq
->rq_flags
& RQF_STATS
) {
432 * We could rq->mq_ctx here, but there's less of a risk
433 * of races if we have the completion event add the stats
434 * to the local software queue.
436 struct blk_mq_ctx
*ctx
;
438 ctx
= __blk_mq_get_ctx(rq
->q
, raw_smp_processor_id());
439 blk_stat_add(&ctx
->stat
[rq_data_dir(rq
)], rq
);
443 static void __blk_mq_complete_request(struct request
*rq
)
445 struct request_queue
*q
= rq
->q
;
449 if (!q
->softirq_done_fn
)
450 blk_mq_end_request(rq
, rq
->errors
);
452 blk_mq_ipi_complete_request(rq
);
456 * blk_mq_complete_request - end I/O on a request
457 * @rq: the request being processed
460 * Ends all I/O on a request. It does not handle partial completions.
461 * The actual completion happens out-of-order, through a IPI handler.
463 void blk_mq_complete_request(struct request
*rq
, int error
)
465 struct request_queue
*q
= rq
->q
;
467 if (unlikely(blk_should_fake_timeout(q
)))
469 if (!blk_mark_rq_complete(rq
)) {
471 __blk_mq_complete_request(rq
);
474 EXPORT_SYMBOL(blk_mq_complete_request
);
476 int blk_mq_request_started(struct request
*rq
)
478 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
480 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
482 void blk_mq_start_request(struct request
*rq
)
484 struct request_queue
*q
= rq
->q
;
486 blk_mq_sched_started_request(rq
);
488 trace_block_rq_issue(q
, rq
);
490 rq
->resid_len
= blk_rq_bytes(rq
);
491 if (unlikely(blk_bidi_rq(rq
)))
492 rq
->next_rq
->resid_len
= blk_rq_bytes(rq
->next_rq
);
494 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
495 blk_stat_set_issue_time(&rq
->issue_stat
);
496 rq
->rq_flags
|= RQF_STATS
;
497 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
503 * Ensure that ->deadline is visible before set the started
504 * flag and clear the completed flag.
506 smp_mb__before_atomic();
509 * Mark us as started and clear complete. Complete might have been
510 * set if requeue raced with timeout, which then marked it as
511 * complete. So be sure to clear complete again when we start
512 * the request, otherwise we'll ignore the completion event.
514 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
515 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
516 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
517 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
519 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
521 * Make sure space for the drain appears. We know we can do
522 * this because max_hw_segments has been adjusted to be one
523 * fewer than the device can handle.
525 rq
->nr_phys_segments
++;
528 EXPORT_SYMBOL(blk_mq_start_request
);
530 static void __blk_mq_requeue_request(struct request
*rq
)
532 struct request_queue
*q
= rq
->q
;
534 trace_block_rq_requeue(q
, rq
);
535 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
536 blk_mq_sched_requeue_request(rq
);
538 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
539 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
540 rq
->nr_phys_segments
--;
544 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
546 __blk_mq_requeue_request(rq
);
548 BUG_ON(blk_queued_rq(rq
));
549 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
551 EXPORT_SYMBOL(blk_mq_requeue_request
);
553 static void blk_mq_requeue_work(struct work_struct
*work
)
555 struct request_queue
*q
=
556 container_of(work
, struct request_queue
, requeue_work
.work
);
558 struct request
*rq
, *next
;
561 spin_lock_irqsave(&q
->requeue_lock
, flags
);
562 list_splice_init(&q
->requeue_list
, &rq_list
);
563 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
565 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
566 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
569 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
570 list_del_init(&rq
->queuelist
);
571 blk_mq_sched_insert_request(rq
, true, false, false);
574 while (!list_empty(&rq_list
)) {
575 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
576 list_del_init(&rq
->queuelist
);
577 blk_mq_sched_insert_request(rq
, false, false, false);
580 blk_mq_run_hw_queues(q
, false);
583 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
584 bool kick_requeue_list
)
586 struct request_queue
*q
= rq
->q
;
590 * We abuse this flag that is otherwise used by the I/O scheduler to
591 * request head insertation from the workqueue.
593 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
595 spin_lock_irqsave(&q
->requeue_lock
, flags
);
597 rq
->rq_flags
|= RQF_SOFTBARRIER
;
598 list_add(&rq
->queuelist
, &q
->requeue_list
);
600 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
602 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
604 if (kick_requeue_list
)
605 blk_mq_kick_requeue_list(q
);
607 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
609 void blk_mq_kick_requeue_list(struct request_queue
*q
)
611 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
613 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
615 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
618 kblockd_schedule_delayed_work(&q
->requeue_work
,
619 msecs_to_jiffies(msecs
));
621 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
623 void blk_mq_abort_requeue_list(struct request_queue
*q
)
628 spin_lock_irqsave(&q
->requeue_lock
, flags
);
629 list_splice_init(&q
->requeue_list
, &rq_list
);
630 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
632 while (!list_empty(&rq_list
)) {
635 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
636 list_del_init(&rq
->queuelist
);
638 blk_mq_end_request(rq
, rq
->errors
);
641 EXPORT_SYMBOL(blk_mq_abort_requeue_list
);
643 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
645 if (tag
< tags
->nr_tags
) {
646 prefetch(tags
->rqs
[tag
]);
647 return tags
->rqs
[tag
];
652 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
654 struct blk_mq_timeout_data
{
656 unsigned int next_set
;
659 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
661 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
662 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
665 * We know that complete is set at this point. If STARTED isn't set
666 * anymore, then the request isn't active and the "timeout" should
667 * just be ignored. This can happen due to the bitflag ordering.
668 * Timeout first checks if STARTED is set, and if it is, assumes
669 * the request is active. But if we race with completion, then
670 * we both flags will get cleared. So check here again, and ignore
671 * a timeout event with a request that isn't active.
673 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
677 ret
= ops
->timeout(req
, reserved
);
681 __blk_mq_complete_request(req
);
683 case BLK_EH_RESET_TIMER
:
685 blk_clear_rq_complete(req
);
687 case BLK_EH_NOT_HANDLED
:
690 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
695 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
696 struct request
*rq
, void *priv
, bool reserved
)
698 struct blk_mq_timeout_data
*data
= priv
;
700 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
702 * If a request wasn't started before the queue was
703 * marked dying, kill it here or it'll go unnoticed.
705 if (unlikely(blk_queue_dying(rq
->q
))) {
707 blk_mq_end_request(rq
, rq
->errors
);
712 if (time_after_eq(jiffies
, rq
->deadline
)) {
713 if (!blk_mark_rq_complete(rq
))
714 blk_mq_rq_timed_out(rq
, reserved
);
715 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
716 data
->next
= rq
->deadline
;
721 static void blk_mq_timeout_work(struct work_struct
*work
)
723 struct request_queue
*q
=
724 container_of(work
, struct request_queue
, timeout_work
);
725 struct blk_mq_timeout_data data
= {
731 /* A deadlock might occur if a request is stuck requiring a
732 * timeout at the same time a queue freeze is waiting
733 * completion, since the timeout code would not be able to
734 * acquire the queue reference here.
736 * That's why we don't use blk_queue_enter here; instead, we use
737 * percpu_ref_tryget directly, because we need to be able to
738 * obtain a reference even in the short window between the queue
739 * starting to freeze, by dropping the first reference in
740 * blk_mq_freeze_queue_start, and the moment the last request is
741 * consumed, marked by the instant q_usage_counter reaches
744 if (!percpu_ref_tryget(&q
->q_usage_counter
))
747 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
750 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
751 mod_timer(&q
->timeout
, data
.next
);
753 struct blk_mq_hw_ctx
*hctx
;
755 queue_for_each_hw_ctx(q
, hctx
, i
) {
756 /* the hctx may be unmapped, so check it here */
757 if (blk_mq_hw_queue_mapped(hctx
))
758 blk_mq_tag_idle(hctx
);
765 * Reverse check our software queue for entries that we could potentially
766 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
767 * too much time checking for merges.
769 static bool blk_mq_attempt_merge(struct request_queue
*q
,
770 struct blk_mq_ctx
*ctx
, struct bio
*bio
)
775 list_for_each_entry_reverse(rq
, &ctx
->rq_list
, queuelist
) {
781 if (!blk_rq_merge_ok(rq
, bio
))
784 el_ret
= blk_try_merge(rq
, bio
);
785 if (el_ret
== ELEVATOR_NO_MERGE
)
788 if (!blk_mq_sched_allow_merge(q
, rq
, bio
))
791 if (el_ret
== ELEVATOR_BACK_MERGE
) {
792 if (bio_attempt_back_merge(q
, rq
, bio
)) {
797 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
798 if (bio_attempt_front_merge(q
, rq
, bio
)) {
809 struct flush_busy_ctx_data
{
810 struct blk_mq_hw_ctx
*hctx
;
811 struct list_head
*list
;
814 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
816 struct flush_busy_ctx_data
*flush_data
= data
;
817 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
818 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
820 sbitmap_clear_bit(sb
, bitnr
);
821 spin_lock(&ctx
->lock
);
822 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
823 spin_unlock(&ctx
->lock
);
828 * Process software queues that have been marked busy, splicing them
829 * to the for-dispatch
831 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
833 struct flush_busy_ctx_data data
= {
838 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
840 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
842 static inline unsigned int queued_to_index(unsigned int queued
)
847 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
850 static bool blk_mq_get_driver_tag(struct request
*rq
,
851 struct blk_mq_hw_ctx
**hctx
, bool wait
)
853 struct blk_mq_alloc_data data
= {
856 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
857 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
860 if (blk_mq_hctx_stopped(data
.hctx
))
870 rq
->tag
= blk_mq_get_tag(&data
);
872 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
880 * If we fail getting a driver tag because all the driver tags are already
881 * assigned and on the dispatch list, BUT the first entry does not have a
882 * tag, then we could deadlock. For that case, move entries with assigned
883 * driver tags to the front, leaving the set of tagged requests in the
884 * same order, and the untagged set in the same order.
886 static bool reorder_tags_to_front(struct list_head
*list
)
888 struct request
*rq
, *tmp
, *first
= NULL
;
890 list_for_each_entry_safe_reverse(rq
, tmp
, list
, queuelist
) {
894 list_move(&rq
->queuelist
, list
);
900 return first
!= NULL
;
903 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
905 struct request_queue
*q
= hctx
->queue
;
907 LIST_HEAD(driver_list
);
908 struct list_head
*dptr
;
909 int queued
, ret
= BLK_MQ_RQ_QUEUE_OK
;
912 * Start off with dptr being NULL, so we start the first request
913 * immediately, even if we have more pending.
918 * Now process all the entries, sending them to the driver.
921 while (!list_empty(list
)) {
922 struct blk_mq_queue_data bd
;
924 rq
= list_first_entry(list
, struct request
, queuelist
);
925 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
926 if (!queued
&& reorder_tags_to_front(list
))
928 blk_mq_sched_mark_restart(hctx
);
931 list_del_init(&rq
->queuelist
);
935 bd
.last
= list_empty(list
);
937 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
939 case BLK_MQ_RQ_QUEUE_OK
:
942 case BLK_MQ_RQ_QUEUE_BUSY
:
943 list_add(&rq
->queuelist
, list
);
944 __blk_mq_requeue_request(rq
);
947 pr_err("blk-mq: bad return on queue: %d\n", ret
);
948 case BLK_MQ_RQ_QUEUE_ERROR
:
950 blk_mq_end_request(rq
, rq
->errors
);
954 if (ret
== BLK_MQ_RQ_QUEUE_BUSY
)
958 * We've done the first request. If we have more than 1
959 * left in the list, set dptr to defer issue.
961 if (!dptr
&& list
->next
!= list
->prev
)
965 hctx
->dispatched
[queued_to_index(queued
)]++;
968 * Any items that need requeuing? Stuff them into hctx->dispatch,
969 * that is where we will continue on next queue run.
971 if (!list_empty(list
)) {
972 spin_lock(&hctx
->lock
);
973 list_splice(list
, &hctx
->dispatch
);
974 spin_unlock(&hctx
->lock
);
977 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
978 * it's possible the queue is stopped and restarted again
979 * before this. Queue restart will dispatch requests. And since
980 * requests in rq_list aren't added into hctx->dispatch yet,
981 * the requests in rq_list might get lost.
983 * blk_mq_run_hw_queue() already checks the STOPPED bit
985 * If RESTART is set, then let completion restart the queue
986 * instead of potentially looping here.
988 if (!blk_mq_sched_needs_restart(hctx
))
989 blk_mq_run_hw_queue(hctx
, true);
992 return ret
!= BLK_MQ_RQ_QUEUE_BUSY
;
995 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
999 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1000 cpu_online(hctx
->next_cpu
));
1002 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1004 blk_mq_sched_dispatch_requests(hctx
);
1007 srcu_idx
= srcu_read_lock(&hctx
->queue_rq_srcu
);
1008 blk_mq_sched_dispatch_requests(hctx
);
1009 srcu_read_unlock(&hctx
->queue_rq_srcu
, srcu_idx
);
1014 * It'd be great if the workqueue API had a way to pass
1015 * in a mask and had some smarts for more clever placement.
1016 * For now we just round-robin here, switching for every
1017 * BLK_MQ_CPU_WORK_BATCH queued items.
1019 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1021 if (hctx
->queue
->nr_hw_queues
== 1)
1022 return WORK_CPU_UNBOUND
;
1024 if (--hctx
->next_cpu_batch
<= 0) {
1027 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
1028 if (next_cpu
>= nr_cpu_ids
)
1029 next_cpu
= cpumask_first(hctx
->cpumask
);
1031 hctx
->next_cpu
= next_cpu
;
1032 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1035 return hctx
->next_cpu
;
1038 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1040 if (unlikely(blk_mq_hctx_stopped(hctx
) ||
1041 !blk_mq_hw_queue_mapped(hctx
)))
1044 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1045 int cpu
= get_cpu();
1046 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1047 __blk_mq_run_hw_queue(hctx
);
1055 kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
);
1058 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1060 struct blk_mq_hw_ctx
*hctx
;
1063 queue_for_each_hw_ctx(q
, hctx
, i
) {
1064 if (!blk_mq_hctx_has_pending(hctx
) ||
1065 blk_mq_hctx_stopped(hctx
))
1068 blk_mq_run_hw_queue(hctx
, async
);
1071 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1074 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1075 * @q: request queue.
1077 * The caller is responsible for serializing this function against
1078 * blk_mq_{start,stop}_hw_queue().
1080 bool blk_mq_queue_stopped(struct request_queue
*q
)
1082 struct blk_mq_hw_ctx
*hctx
;
1085 queue_for_each_hw_ctx(q
, hctx
, i
)
1086 if (blk_mq_hctx_stopped(hctx
))
1091 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1093 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1095 cancel_work(&hctx
->run_work
);
1096 cancel_delayed_work(&hctx
->delay_work
);
1097 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1099 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1101 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1103 struct blk_mq_hw_ctx
*hctx
;
1106 queue_for_each_hw_ctx(q
, hctx
, i
)
1107 blk_mq_stop_hw_queue(hctx
);
1109 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1111 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1113 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1115 blk_mq_run_hw_queue(hctx
, false);
1117 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1119 void blk_mq_start_hw_queues(struct request_queue
*q
)
1121 struct blk_mq_hw_ctx
*hctx
;
1124 queue_for_each_hw_ctx(q
, hctx
, i
)
1125 blk_mq_start_hw_queue(hctx
);
1127 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1129 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1131 if (!blk_mq_hctx_stopped(hctx
))
1134 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1135 blk_mq_run_hw_queue(hctx
, async
);
1137 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1139 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1141 struct blk_mq_hw_ctx
*hctx
;
1144 queue_for_each_hw_ctx(q
, hctx
, i
)
1145 blk_mq_start_stopped_hw_queue(hctx
, async
);
1147 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1149 static void blk_mq_run_work_fn(struct work_struct
*work
)
1151 struct blk_mq_hw_ctx
*hctx
;
1153 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
);
1155 __blk_mq_run_hw_queue(hctx
);
1158 static void blk_mq_delay_work_fn(struct work_struct
*work
)
1160 struct blk_mq_hw_ctx
*hctx
;
1162 hctx
= container_of(work
, struct blk_mq_hw_ctx
, delay_work
.work
);
1164 if (test_and_clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1165 __blk_mq_run_hw_queue(hctx
);
1168 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1170 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
1173 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1174 &hctx
->delay_work
, msecs_to_jiffies(msecs
));
1176 EXPORT_SYMBOL(blk_mq_delay_queue
);
1178 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1182 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1184 trace_block_rq_insert(hctx
->queue
, rq
);
1187 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1189 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1192 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1195 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1197 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1198 blk_mq_hctx_mark_pending(hctx
, ctx
);
1201 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1202 struct list_head
*list
)
1206 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1209 spin_lock(&ctx
->lock
);
1210 while (!list_empty(list
)) {
1213 rq
= list_first_entry(list
, struct request
, queuelist
);
1214 BUG_ON(rq
->mq_ctx
!= ctx
);
1215 list_del_init(&rq
->queuelist
);
1216 __blk_mq_insert_req_list(hctx
, rq
, false);
1218 blk_mq_hctx_mark_pending(hctx
, ctx
);
1219 spin_unlock(&ctx
->lock
);
1222 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1224 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1225 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1227 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1228 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1229 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1232 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1234 struct blk_mq_ctx
*this_ctx
;
1235 struct request_queue
*this_q
;
1238 LIST_HEAD(ctx_list
);
1241 list_splice_init(&plug
->mq_list
, &list
);
1243 list_sort(NULL
, &list
, plug_ctx_cmp
);
1249 while (!list_empty(&list
)) {
1250 rq
= list_entry_rq(list
.next
);
1251 list_del_init(&rq
->queuelist
);
1253 if (rq
->mq_ctx
!= this_ctx
) {
1255 trace_block_unplug(this_q
, depth
, from_schedule
);
1256 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1261 this_ctx
= rq
->mq_ctx
;
1267 list_add_tail(&rq
->queuelist
, &ctx_list
);
1271 * If 'this_ctx' is set, we know we have entries to complete
1272 * on 'ctx_list'. Do those.
1275 trace_block_unplug(this_q
, depth
, from_schedule
);
1276 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1281 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1283 init_request_from_bio(rq
, bio
);
1285 blk_account_io_start(rq
, true);
1288 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1290 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1291 !blk_queue_nomerges(hctx
->queue
);
1294 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx
*hctx
,
1295 struct blk_mq_ctx
*ctx
,
1296 struct request
*rq
, struct bio
*bio
)
1298 if (!hctx_allow_merges(hctx
) || !bio_mergeable(bio
)) {
1299 blk_mq_bio_to_request(rq
, bio
);
1300 spin_lock(&ctx
->lock
);
1302 __blk_mq_insert_request(hctx
, rq
, false);
1303 spin_unlock(&ctx
->lock
);
1306 struct request_queue
*q
= hctx
->queue
;
1308 spin_lock(&ctx
->lock
);
1309 if (!blk_mq_attempt_merge(q
, ctx
, bio
)) {
1310 blk_mq_bio_to_request(rq
, bio
);
1314 spin_unlock(&ctx
->lock
);
1315 __blk_mq_finish_request(hctx
, ctx
, rq
);
1320 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1323 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1325 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1328 static void blk_mq_try_issue_directly(struct request
*rq
, blk_qc_t
*cookie
)
1330 struct request_queue
*q
= rq
->q
;
1331 struct blk_mq_queue_data bd
= {
1336 struct blk_mq_hw_ctx
*hctx
;
1337 blk_qc_t new_cookie
;
1343 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
1346 new_cookie
= request_to_qc_t(hctx
, rq
);
1349 * For OK queue, we are done. For error, kill it. Any other
1350 * error (busy), just add it to our list as we previously
1353 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1354 if (ret
== BLK_MQ_RQ_QUEUE_OK
) {
1355 *cookie
= new_cookie
;
1359 __blk_mq_requeue_request(rq
);
1361 if (ret
== BLK_MQ_RQ_QUEUE_ERROR
) {
1362 *cookie
= BLK_QC_T_NONE
;
1364 blk_mq_end_request(rq
, rq
->errors
);
1369 blk_mq_sched_insert_request(rq
, false, true, true);
1373 * Multiple hardware queue variant. This will not use per-process plugs,
1374 * but will attempt to bypass the hctx queueing if we can go straight to
1375 * hardware for SYNC IO.
1377 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1379 const int is_sync
= op_is_sync(bio
->bi_opf
);
1380 const int is_flush_fua
= bio
->bi_opf
& (REQ_PREFLUSH
| REQ_FUA
);
1381 struct blk_mq_alloc_data data
;
1383 unsigned int request_count
= 0, srcu_idx
;
1384 struct blk_plug
*plug
;
1385 struct request
*same_queue_rq
= NULL
;
1387 unsigned int wb_acct
;
1389 blk_queue_bounce(q
, &bio
);
1391 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1393 return BLK_QC_T_NONE
;
1396 blk_queue_split(q
, &bio
, q
->bio_split
);
1398 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1399 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1400 return BLK_QC_T_NONE
;
1402 if (blk_mq_sched_bio_merge(q
, bio
))
1403 return BLK_QC_T_NONE
;
1405 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1407 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1409 rq
= blk_mq_sched_get_request(q
, bio
, bio
->bi_opf
, &data
);
1410 if (unlikely(!rq
)) {
1411 __wbt_done(q
->rq_wb
, wb_acct
);
1412 return BLK_QC_T_NONE
;
1415 wbt_track(&rq
->issue_stat
, wb_acct
);
1417 cookie
= request_to_qc_t(data
.hctx
, rq
);
1419 if (unlikely(is_flush_fua
)) {
1420 blk_mq_bio_to_request(rq
, bio
);
1421 blk_mq_get_driver_tag(rq
, NULL
, true);
1422 blk_insert_flush(rq
);
1426 plug
= current
->plug
;
1428 * If the driver supports defer issued based on 'last', then
1429 * queue it up like normal since we can potentially save some
1432 if (((plug
&& !blk_queue_nomerges(q
)) || is_sync
) &&
1433 !(data
.hctx
->flags
& BLK_MQ_F_DEFER_ISSUE
)) {
1434 struct request
*old_rq
= NULL
;
1436 blk_mq_bio_to_request(rq
, bio
);
1439 * We do limited plugging. If the bio can be merged, do that.
1440 * Otherwise the existing request in the plug list will be
1441 * issued. So the plug list will have one request at most
1445 * The plug list might get flushed before this. If that
1446 * happens, same_queue_rq is invalid and plug list is
1449 if (same_queue_rq
&& !list_empty(&plug
->mq_list
)) {
1450 old_rq
= same_queue_rq
;
1451 list_del_init(&old_rq
->queuelist
);
1453 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1454 } else /* is_sync */
1456 blk_mq_put_ctx(data
.ctx
);
1460 if (!(data
.hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1462 blk_mq_try_issue_directly(old_rq
, &cookie
);
1465 srcu_idx
= srcu_read_lock(&data
.hctx
->queue_rq_srcu
);
1466 blk_mq_try_issue_directly(old_rq
, &cookie
);
1467 srcu_read_unlock(&data
.hctx
->queue_rq_srcu
, srcu_idx
);
1473 blk_mq_put_ctx(data
.ctx
);
1474 blk_mq_bio_to_request(rq
, bio
);
1475 blk_mq_sched_insert_request(rq
, false, true, true);
1478 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1480 * For a SYNC request, send it to the hardware immediately. For
1481 * an ASYNC request, just ensure that we run it later on. The
1482 * latter allows for merging opportunities and more efficient
1486 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1488 blk_mq_put_ctx(data
.ctx
);
1494 * Single hardware queue variant. This will attempt to use any per-process
1495 * plug for merging and IO deferral.
1497 static blk_qc_t
blk_sq_make_request(struct request_queue
*q
, struct bio
*bio
)
1499 const int is_sync
= op_is_sync(bio
->bi_opf
);
1500 const int is_flush_fua
= bio
->bi_opf
& (REQ_PREFLUSH
| REQ_FUA
);
1501 struct blk_plug
*plug
;
1502 unsigned int request_count
= 0;
1503 struct blk_mq_alloc_data data
;
1506 unsigned int wb_acct
;
1508 blk_queue_bounce(q
, &bio
);
1510 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1512 return BLK_QC_T_NONE
;
1515 blk_queue_split(q
, &bio
, q
->bio_split
);
1517 if (!is_flush_fua
&& !blk_queue_nomerges(q
)) {
1518 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1519 return BLK_QC_T_NONE
;
1521 request_count
= blk_plug_queued_count(q
);
1523 if (blk_mq_sched_bio_merge(q
, bio
))
1524 return BLK_QC_T_NONE
;
1526 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1528 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1530 rq
= blk_mq_sched_get_request(q
, bio
, bio
->bi_opf
, &data
);
1531 if (unlikely(!rq
)) {
1532 __wbt_done(q
->rq_wb
, wb_acct
);
1533 return BLK_QC_T_NONE
;
1536 wbt_track(&rq
->issue_stat
, wb_acct
);
1538 cookie
= request_to_qc_t(data
.hctx
, rq
);
1540 if (unlikely(is_flush_fua
)) {
1541 blk_mq_bio_to_request(rq
, bio
);
1542 blk_mq_get_driver_tag(rq
, NULL
, true);
1543 blk_insert_flush(rq
);
1548 * A task plug currently exists. Since this is completely lockless,
1549 * utilize that to temporarily store requests until the task is
1550 * either done or scheduled away.
1552 plug
= current
->plug
;
1554 struct request
*last
= NULL
;
1556 blk_mq_bio_to_request(rq
, bio
);
1559 * @request_count may become stale because of schedule
1560 * out, so check the list again.
1562 if (list_empty(&plug
->mq_list
))
1565 trace_block_plug(q
);
1567 last
= list_entry_rq(plug
->mq_list
.prev
);
1569 blk_mq_put_ctx(data
.ctx
);
1571 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1572 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1573 blk_flush_plug_list(plug
, false);
1574 trace_block_plug(q
);
1577 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1582 blk_mq_put_ctx(data
.ctx
);
1583 blk_mq_bio_to_request(rq
, bio
);
1584 blk_mq_sched_insert_request(rq
, false, true, true);
1587 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1589 * For a SYNC request, send it to the hardware immediately. For
1590 * an ASYNC request, just ensure that we run it later on. The
1591 * latter allows for merging opportunities and more efficient
1595 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1598 blk_mq_put_ctx(data
.ctx
);
1603 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1604 unsigned int hctx_idx
)
1608 if (tags
->rqs
&& set
->ops
->exit_request
) {
1611 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1612 struct request
*rq
= tags
->static_rqs
[i
];
1616 set
->ops
->exit_request(set
->driver_data
, rq
,
1618 tags
->static_rqs
[i
] = NULL
;
1622 while (!list_empty(&tags
->page_list
)) {
1623 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1624 list_del_init(&page
->lru
);
1626 * Remove kmemleak object previously allocated in
1627 * blk_mq_init_rq_map().
1629 kmemleak_free(page_address(page
));
1630 __free_pages(page
, page
->private);
1634 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1638 kfree(tags
->static_rqs
);
1639 tags
->static_rqs
= NULL
;
1641 blk_mq_free_tags(tags
);
1644 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1645 unsigned int hctx_idx
,
1646 unsigned int nr_tags
,
1647 unsigned int reserved_tags
)
1649 struct blk_mq_tags
*tags
;
1651 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
,
1653 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1657 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1658 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1661 blk_mq_free_tags(tags
);
1665 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1666 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1668 if (!tags
->static_rqs
) {
1670 blk_mq_free_tags(tags
);
1677 static size_t order_to_size(unsigned int order
)
1679 return (size_t)PAGE_SIZE
<< order
;
1682 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1683 unsigned int hctx_idx
, unsigned int depth
)
1685 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1686 size_t rq_size
, left
;
1688 INIT_LIST_HEAD(&tags
->page_list
);
1691 * rq_size is the size of the request plus driver payload, rounded
1692 * to the cacheline size
1694 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1696 left
= rq_size
* depth
;
1698 for (i
= 0; i
< depth
; ) {
1699 int this_order
= max_order
;
1704 while (this_order
&& left
< order_to_size(this_order
- 1))
1708 page
= alloc_pages_node(set
->numa_node
,
1709 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1715 if (order_to_size(this_order
) < rq_size
)
1722 page
->private = this_order
;
1723 list_add_tail(&page
->lru
, &tags
->page_list
);
1725 p
= page_address(page
);
1727 * Allow kmemleak to scan these pages as they contain pointers
1728 * to additional allocations like via ops->init_request().
1730 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1731 entries_per_page
= order_to_size(this_order
) / rq_size
;
1732 to_do
= min(entries_per_page
, depth
- i
);
1733 left
-= to_do
* rq_size
;
1734 for (j
= 0; j
< to_do
; j
++) {
1735 struct request
*rq
= p
;
1737 tags
->static_rqs
[i
] = rq
;
1738 if (set
->ops
->init_request
) {
1739 if (set
->ops
->init_request(set
->driver_data
,
1742 tags
->static_rqs
[i
] = NULL
;
1754 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1759 * 'cpu' is going away. splice any existing rq_list entries from this
1760 * software queue to the hw queue dispatch list, and ensure that it
1763 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1765 struct blk_mq_hw_ctx
*hctx
;
1766 struct blk_mq_ctx
*ctx
;
1769 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1770 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1772 spin_lock(&ctx
->lock
);
1773 if (!list_empty(&ctx
->rq_list
)) {
1774 list_splice_init(&ctx
->rq_list
, &tmp
);
1775 blk_mq_hctx_clear_pending(hctx
, ctx
);
1777 spin_unlock(&ctx
->lock
);
1779 if (list_empty(&tmp
))
1782 spin_lock(&hctx
->lock
);
1783 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1784 spin_unlock(&hctx
->lock
);
1786 blk_mq_run_hw_queue(hctx
, true);
1790 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
1792 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
1796 /* hctx->ctxs will be freed in queue's release handler */
1797 static void blk_mq_exit_hctx(struct request_queue
*q
,
1798 struct blk_mq_tag_set
*set
,
1799 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1801 unsigned flush_start_tag
= set
->queue_depth
;
1803 blk_mq_tag_idle(hctx
);
1805 if (set
->ops
->exit_request
)
1806 set
->ops
->exit_request(set
->driver_data
,
1807 hctx
->fq
->flush_rq
, hctx_idx
,
1808 flush_start_tag
+ hctx_idx
);
1810 if (set
->ops
->exit_hctx
)
1811 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1813 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1814 cleanup_srcu_struct(&hctx
->queue_rq_srcu
);
1816 blk_mq_remove_cpuhp(hctx
);
1817 blk_free_flush_queue(hctx
->fq
);
1818 sbitmap_free(&hctx
->ctx_map
);
1821 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1822 struct blk_mq_tag_set
*set
, int nr_queue
)
1824 struct blk_mq_hw_ctx
*hctx
;
1827 queue_for_each_hw_ctx(q
, hctx
, i
) {
1830 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1834 static void blk_mq_free_hw_queues(struct request_queue
*q
,
1835 struct blk_mq_tag_set
*set
)
1837 struct blk_mq_hw_ctx
*hctx
;
1840 queue_for_each_hw_ctx(q
, hctx
, i
)
1841 free_cpumask_var(hctx
->cpumask
);
1844 static int blk_mq_init_hctx(struct request_queue
*q
,
1845 struct blk_mq_tag_set
*set
,
1846 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1849 unsigned flush_start_tag
= set
->queue_depth
;
1851 node
= hctx
->numa_node
;
1852 if (node
== NUMA_NO_NODE
)
1853 node
= hctx
->numa_node
= set
->numa_node
;
1855 INIT_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1856 INIT_DELAYED_WORK(&hctx
->delay_work
, blk_mq_delay_work_fn
);
1857 spin_lock_init(&hctx
->lock
);
1858 INIT_LIST_HEAD(&hctx
->dispatch
);
1860 hctx
->queue_num
= hctx_idx
;
1861 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1863 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
1865 hctx
->tags
= set
->tags
[hctx_idx
];
1868 * Allocate space for all possible cpus to avoid allocation at
1871 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1874 goto unregister_cpu_notifier
;
1876 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
1882 if (set
->ops
->init_hctx
&&
1883 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1886 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
1890 if (set
->ops
->init_request
&&
1891 set
->ops
->init_request(set
->driver_data
,
1892 hctx
->fq
->flush_rq
, hctx_idx
,
1893 flush_start_tag
+ hctx_idx
, node
))
1896 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1897 init_srcu_struct(&hctx
->queue_rq_srcu
);
1904 if (set
->ops
->exit_hctx
)
1905 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1907 sbitmap_free(&hctx
->ctx_map
);
1910 unregister_cpu_notifier
:
1911 blk_mq_remove_cpuhp(hctx
);
1915 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
1916 unsigned int nr_hw_queues
)
1920 for_each_possible_cpu(i
) {
1921 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1922 struct blk_mq_hw_ctx
*hctx
;
1924 memset(__ctx
, 0, sizeof(*__ctx
));
1926 spin_lock_init(&__ctx
->lock
);
1927 INIT_LIST_HEAD(&__ctx
->rq_list
);
1929 blk_stat_init(&__ctx
->stat
[BLK_STAT_READ
]);
1930 blk_stat_init(&__ctx
->stat
[BLK_STAT_WRITE
]);
1932 /* If the cpu isn't online, the cpu is mapped to first hctx */
1936 hctx
= blk_mq_map_queue(q
, i
);
1939 * Set local node, IFF we have more than one hw queue. If
1940 * not, we remain on the home node of the device
1942 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
1943 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
1947 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
1951 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
1952 set
->queue_depth
, set
->reserved_tags
);
1953 if (!set
->tags
[hctx_idx
])
1956 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
1961 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
1962 set
->tags
[hctx_idx
] = NULL
;
1966 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
1967 unsigned int hctx_idx
)
1969 if (set
->tags
[hctx_idx
]) {
1970 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
1971 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
1972 set
->tags
[hctx_idx
] = NULL
;
1976 static void blk_mq_map_swqueue(struct request_queue
*q
,
1977 const struct cpumask
*online_mask
)
1979 unsigned int i
, hctx_idx
;
1980 struct blk_mq_hw_ctx
*hctx
;
1981 struct blk_mq_ctx
*ctx
;
1982 struct blk_mq_tag_set
*set
= q
->tag_set
;
1985 * Avoid others reading imcomplete hctx->cpumask through sysfs
1987 mutex_lock(&q
->sysfs_lock
);
1989 queue_for_each_hw_ctx(q
, hctx
, i
) {
1990 cpumask_clear(hctx
->cpumask
);
1995 * Map software to hardware queues
1997 for_each_possible_cpu(i
) {
1998 /* If the cpu isn't online, the cpu is mapped to first hctx */
1999 if (!cpumask_test_cpu(i
, online_mask
))
2002 hctx_idx
= q
->mq_map
[i
];
2003 /* unmapped hw queue can be remapped after CPU topo changed */
2004 if (!set
->tags
[hctx_idx
] &&
2005 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2007 * If tags initialization fail for some hctx,
2008 * that hctx won't be brought online. In this
2009 * case, remap the current ctx to hctx[0] which
2010 * is guaranteed to always have tags allocated
2015 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2016 hctx
= blk_mq_map_queue(q
, i
);
2018 cpumask_set_cpu(i
, hctx
->cpumask
);
2019 ctx
->index_hw
= hctx
->nr_ctx
;
2020 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2023 mutex_unlock(&q
->sysfs_lock
);
2025 queue_for_each_hw_ctx(q
, hctx
, i
) {
2027 * If no software queues are mapped to this hardware queue,
2028 * disable it and free the request entries.
2030 if (!hctx
->nr_ctx
) {
2031 /* Never unmap queue 0. We need it as a
2032 * fallback in case of a new remap fails
2035 if (i
&& set
->tags
[i
])
2036 blk_mq_free_map_and_requests(set
, i
);
2042 hctx
->tags
= set
->tags
[i
];
2043 WARN_ON(!hctx
->tags
);
2046 * Set the map size to the number of mapped software queues.
2047 * This is more accurate and more efficient than looping
2048 * over all possibly mapped software queues.
2050 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2053 * Initialize batch roundrobin counts
2055 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2056 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2060 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2062 struct blk_mq_hw_ctx
*hctx
;
2065 queue_for_each_hw_ctx(q
, hctx
, i
) {
2067 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2069 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2073 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
2075 struct request_queue
*q
;
2077 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2078 blk_mq_freeze_queue(q
);
2079 queue_set_hctx_shared(q
, shared
);
2080 blk_mq_unfreeze_queue(q
);
2084 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2086 struct blk_mq_tag_set
*set
= q
->tag_set
;
2088 mutex_lock(&set
->tag_list_lock
);
2089 list_del_init(&q
->tag_set_list
);
2090 if (list_is_singular(&set
->tag_list
)) {
2091 /* just transitioned to unshared */
2092 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2093 /* update existing queue */
2094 blk_mq_update_tag_set_depth(set
, false);
2096 mutex_unlock(&set
->tag_list_lock
);
2099 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2100 struct request_queue
*q
)
2104 mutex_lock(&set
->tag_list_lock
);
2106 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2107 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2108 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2109 /* update existing queue */
2110 blk_mq_update_tag_set_depth(set
, true);
2112 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2113 queue_set_hctx_shared(q
, true);
2114 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
2116 mutex_unlock(&set
->tag_list_lock
);
2120 * It is the actual release handler for mq, but we do it from
2121 * request queue's release handler for avoiding use-after-free
2122 * and headache because q->mq_kobj shouldn't have been introduced,
2123 * but we can't group ctx/kctx kobj without it.
2125 void blk_mq_release(struct request_queue
*q
)
2127 struct blk_mq_hw_ctx
*hctx
;
2130 blk_mq_sched_teardown(q
);
2132 /* hctx kobj stays in hctx */
2133 queue_for_each_hw_ctx(q
, hctx
, i
) {
2142 kfree(q
->queue_hw_ctx
);
2144 /* ctx kobj stays in queue_ctx */
2145 free_percpu(q
->queue_ctx
);
2148 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2150 struct request_queue
*uninit_q
, *q
;
2152 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2154 return ERR_PTR(-ENOMEM
);
2156 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2158 blk_cleanup_queue(uninit_q
);
2162 EXPORT_SYMBOL(blk_mq_init_queue
);
2164 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2165 struct request_queue
*q
)
2168 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2170 blk_mq_sysfs_unregister(q
);
2171 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2177 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2178 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
2183 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2190 atomic_set(&hctxs
[i
]->nr_active
, 0);
2191 hctxs
[i
]->numa_node
= node
;
2192 hctxs
[i
]->queue_num
= i
;
2194 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2195 free_cpumask_var(hctxs
[i
]->cpumask
);
2200 blk_mq_hctx_kobj_init(hctxs
[i
]);
2202 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2203 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2207 blk_mq_free_map_and_requests(set
, j
);
2208 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2209 free_cpumask_var(hctx
->cpumask
);
2210 kobject_put(&hctx
->kobj
);
2217 q
->nr_hw_queues
= i
;
2218 blk_mq_sysfs_register(q
);
2221 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2222 struct request_queue
*q
)
2224 /* mark the queue as mq asap */
2225 q
->mq_ops
= set
->ops
;
2227 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2231 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2232 GFP_KERNEL
, set
->numa_node
);
2233 if (!q
->queue_hw_ctx
)
2236 q
->mq_map
= set
->mq_map
;
2238 blk_mq_realloc_hw_ctxs(set
, q
);
2239 if (!q
->nr_hw_queues
)
2242 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2243 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2245 q
->nr_queues
= nr_cpu_ids
;
2247 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2249 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2250 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2252 q
->sg_reserved_size
= INT_MAX
;
2254 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2255 INIT_LIST_HEAD(&q
->requeue_list
);
2256 spin_lock_init(&q
->requeue_lock
);
2258 if (q
->nr_hw_queues
> 1)
2259 blk_queue_make_request(q
, blk_mq_make_request
);
2261 blk_queue_make_request(q
, blk_sq_make_request
);
2264 * Do this after blk_queue_make_request() overrides it...
2266 q
->nr_requests
= set
->queue_depth
;
2269 * Default to classic polling
2273 if (set
->ops
->complete
)
2274 blk_queue_softirq_done(q
, set
->ops
->complete
);
2276 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2279 mutex_lock(&all_q_mutex
);
2281 list_add_tail(&q
->all_q_node
, &all_q_list
);
2282 blk_mq_add_queue_tag_set(set
, q
);
2283 blk_mq_map_swqueue(q
, cpu_online_mask
);
2285 mutex_unlock(&all_q_mutex
);
2288 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2291 ret
= blk_mq_sched_init(q
);
2293 return ERR_PTR(ret
);
2299 kfree(q
->queue_hw_ctx
);
2301 free_percpu(q
->queue_ctx
);
2304 return ERR_PTR(-ENOMEM
);
2306 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2308 void blk_mq_free_queue(struct request_queue
*q
)
2310 struct blk_mq_tag_set
*set
= q
->tag_set
;
2312 mutex_lock(&all_q_mutex
);
2313 list_del_init(&q
->all_q_node
);
2314 mutex_unlock(&all_q_mutex
);
2318 blk_mq_del_queue_tag_set(q
);
2320 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2321 blk_mq_free_hw_queues(q
, set
);
2324 /* Basically redo blk_mq_init_queue with queue frozen */
2325 static void blk_mq_queue_reinit(struct request_queue
*q
,
2326 const struct cpumask
*online_mask
)
2328 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2330 blk_mq_sysfs_unregister(q
);
2333 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2334 * we should change hctx numa_node according to new topology (this
2335 * involves free and re-allocate memory, worthy doing?)
2338 blk_mq_map_swqueue(q
, online_mask
);
2340 blk_mq_sysfs_register(q
);
2344 * New online cpumask which is going to be set in this hotplug event.
2345 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2346 * one-by-one and dynamically allocating this could result in a failure.
2348 static struct cpumask cpuhp_online_new
;
2350 static void blk_mq_queue_reinit_work(void)
2352 struct request_queue
*q
;
2354 mutex_lock(&all_q_mutex
);
2356 * We need to freeze and reinit all existing queues. Freezing
2357 * involves synchronous wait for an RCU grace period and doing it
2358 * one by one may take a long time. Start freezing all queues in
2359 * one swoop and then wait for the completions so that freezing can
2360 * take place in parallel.
2362 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2363 blk_mq_freeze_queue_start(q
);
2364 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2365 blk_mq_freeze_queue_wait(q
);
2367 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2368 blk_mq_queue_reinit(q
, &cpuhp_online_new
);
2370 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2371 blk_mq_unfreeze_queue(q
);
2373 mutex_unlock(&all_q_mutex
);
2376 static int blk_mq_queue_reinit_dead(unsigned int cpu
)
2378 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2379 blk_mq_queue_reinit_work();
2384 * Before hotadded cpu starts handling requests, new mappings must be
2385 * established. Otherwise, these requests in hw queue might never be
2388 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2389 * for CPU0, and ctx1 for CPU1).
2391 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2392 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2394 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2395 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2396 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2399 static int blk_mq_queue_reinit_prepare(unsigned int cpu
)
2401 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2402 cpumask_set_cpu(cpu
, &cpuhp_online_new
);
2403 blk_mq_queue_reinit_work();
2407 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2411 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2412 if (!__blk_mq_alloc_rq_map(set
, i
))
2419 blk_mq_free_rq_map(set
->tags
[i
]);
2425 * Allocate the request maps associated with this tag_set. Note that this
2426 * may reduce the depth asked for, if memory is tight. set->queue_depth
2427 * will be updated to reflect the allocated depth.
2429 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2434 depth
= set
->queue_depth
;
2436 err
= __blk_mq_alloc_rq_maps(set
);
2440 set
->queue_depth
>>= 1;
2441 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2445 } while (set
->queue_depth
);
2447 if (!set
->queue_depth
|| err
) {
2448 pr_err("blk-mq: failed to allocate request map\n");
2452 if (depth
!= set
->queue_depth
)
2453 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2454 depth
, set
->queue_depth
);
2460 * Alloc a tag set to be associated with one or more request queues.
2461 * May fail with EINVAL for various error conditions. May adjust the
2462 * requested depth down, if if it too large. In that case, the set
2463 * value will be stored in set->queue_depth.
2465 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2469 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2471 if (!set
->nr_hw_queues
)
2473 if (!set
->queue_depth
)
2475 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2478 if (!set
->ops
->queue_rq
)
2481 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2482 pr_info("blk-mq: reduced tag depth to %u\n",
2484 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2488 * If a crashdump is active, then we are potentially in a very
2489 * memory constrained environment. Limit us to 1 queue and
2490 * 64 tags to prevent using too much memory.
2492 if (is_kdump_kernel()) {
2493 set
->nr_hw_queues
= 1;
2494 set
->queue_depth
= min(64U, set
->queue_depth
);
2497 * There is no use for more h/w queues than cpus.
2499 if (set
->nr_hw_queues
> nr_cpu_ids
)
2500 set
->nr_hw_queues
= nr_cpu_ids
;
2502 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2503 GFP_KERNEL
, set
->numa_node
);
2508 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2509 GFP_KERNEL
, set
->numa_node
);
2513 if (set
->ops
->map_queues
)
2514 ret
= set
->ops
->map_queues(set
);
2516 ret
= blk_mq_map_queues(set
);
2518 goto out_free_mq_map
;
2520 ret
= blk_mq_alloc_rq_maps(set
);
2522 goto out_free_mq_map
;
2524 mutex_init(&set
->tag_list_lock
);
2525 INIT_LIST_HEAD(&set
->tag_list
);
2537 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2539 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2543 for (i
= 0; i
< nr_cpu_ids
; i
++)
2544 blk_mq_free_map_and_requests(set
, i
);
2552 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2554 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2556 struct blk_mq_tag_set
*set
= q
->tag_set
;
2557 struct blk_mq_hw_ctx
*hctx
;
2564 queue_for_each_hw_ctx(q
, hctx
, i
) {
2568 * If we're using an MQ scheduler, just update the scheduler
2569 * queue depth. This is similar to what the old code would do.
2571 if (!hctx
->sched_tags
)
2572 ret
= blk_mq_tag_update_depth(hctx
->tags
,
2573 min(nr
, set
->queue_depth
));
2575 ret
= blk_mq_tag_update_depth(hctx
->sched_tags
, nr
);
2581 q
->nr_requests
= nr
;
2586 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2588 struct request_queue
*q
;
2590 if (nr_hw_queues
> nr_cpu_ids
)
2591 nr_hw_queues
= nr_cpu_ids
;
2592 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2595 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2596 blk_mq_freeze_queue(q
);
2598 set
->nr_hw_queues
= nr_hw_queues
;
2599 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2600 blk_mq_realloc_hw_ctxs(set
, q
);
2602 if (q
->nr_hw_queues
> 1)
2603 blk_queue_make_request(q
, blk_mq_make_request
);
2605 blk_queue_make_request(q
, blk_sq_make_request
);
2607 blk_mq_queue_reinit(q
, cpu_online_mask
);
2610 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2611 blk_mq_unfreeze_queue(q
);
2613 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2615 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2616 struct blk_mq_hw_ctx
*hctx
,
2619 struct blk_rq_stat stat
[2];
2620 unsigned long ret
= 0;
2623 * If stats collection isn't on, don't sleep but turn it on for
2626 if (!blk_stat_enable(q
))
2630 * We don't have to do this once per IO, should optimize this
2631 * to just use the current window of stats until it changes
2633 memset(&stat
, 0, sizeof(stat
));
2634 blk_hctx_stat_get(hctx
, stat
);
2637 * As an optimistic guess, use half of the mean service time
2638 * for this type of request. We can (and should) make this smarter.
2639 * For instance, if the completion latencies are tight, we can
2640 * get closer than just half the mean. This is especially
2641 * important on devices where the completion latencies are longer
2644 if (req_op(rq
) == REQ_OP_READ
&& stat
[BLK_STAT_READ
].nr_samples
)
2645 ret
= (stat
[BLK_STAT_READ
].mean
+ 1) / 2;
2646 else if (req_op(rq
) == REQ_OP_WRITE
&& stat
[BLK_STAT_WRITE
].nr_samples
)
2647 ret
= (stat
[BLK_STAT_WRITE
].mean
+ 1) / 2;
2652 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2653 struct blk_mq_hw_ctx
*hctx
,
2656 struct hrtimer_sleeper hs
;
2657 enum hrtimer_mode mode
;
2661 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2667 * -1: don't ever hybrid sleep
2668 * 0: use half of prev avg
2669 * >0: use this specific value
2671 if (q
->poll_nsec
== -1)
2673 else if (q
->poll_nsec
> 0)
2674 nsecs
= q
->poll_nsec
;
2676 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2681 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2684 * This will be replaced with the stats tracking code, using
2685 * 'avg_completion_time / 2' as the pre-sleep target.
2689 mode
= HRTIMER_MODE_REL
;
2690 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2691 hrtimer_set_expires(&hs
.timer
, kt
);
2693 hrtimer_init_sleeper(&hs
, current
);
2695 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2697 set_current_state(TASK_UNINTERRUPTIBLE
);
2698 hrtimer_start_expires(&hs
.timer
, mode
);
2701 hrtimer_cancel(&hs
.timer
);
2702 mode
= HRTIMER_MODE_ABS
;
2703 } while (hs
.task
&& !signal_pending(current
));
2705 __set_current_state(TASK_RUNNING
);
2706 destroy_hrtimer_on_stack(&hs
.timer
);
2710 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2712 struct request_queue
*q
= hctx
->queue
;
2716 * If we sleep, have the caller restart the poll loop to reset
2717 * the state. Like for the other success return cases, the
2718 * caller is responsible for checking if the IO completed. If
2719 * the IO isn't complete, we'll get called again and will go
2720 * straight to the busy poll loop.
2722 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2725 hctx
->poll_considered
++;
2727 state
= current
->state
;
2728 while (!need_resched()) {
2731 hctx
->poll_invoked
++;
2733 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2735 hctx
->poll_success
++;
2736 set_current_state(TASK_RUNNING
);
2740 if (signal_pending_state(state
, current
))
2741 set_current_state(TASK_RUNNING
);
2743 if (current
->state
== TASK_RUNNING
)
2753 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2755 struct blk_mq_hw_ctx
*hctx
;
2756 struct blk_plug
*plug
;
2759 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
2760 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2763 plug
= current
->plug
;
2765 blk_flush_plug_list(plug
, false);
2767 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2768 if (!blk_qc_t_is_internal(cookie
))
2769 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2771 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2773 return __blk_mq_poll(hctx
, rq
);
2775 EXPORT_SYMBOL_GPL(blk_mq_poll
);
2777 void blk_mq_disable_hotplug(void)
2779 mutex_lock(&all_q_mutex
);
2782 void blk_mq_enable_hotplug(void)
2784 mutex_unlock(&all_q_mutex
);
2787 static int __init
blk_mq_init(void)
2789 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
2790 blk_mq_hctx_notify_dead
);
2792 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE
, "block/mq:prepare",
2793 blk_mq_queue_reinit_prepare
,
2794 blk_mq_queue_reinit_dead
);
2797 subsys_initcall(blk_mq_init
);