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"
34 static DEFINE_MUTEX(all_q_mutex
);
35 static LIST_HEAD(all_q_list
);
38 * Check if any of the ctx's have pending work in this hardware queue
40 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
42 return sbitmap_any_bit_set(&hctx
->ctx_map
);
46 * Mark this ctx as having pending work in this hardware queue
48 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
49 struct blk_mq_ctx
*ctx
)
51 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
52 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
55 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
56 struct blk_mq_ctx
*ctx
)
58 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
61 void blk_mq_freeze_queue_start(struct request_queue
*q
)
65 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
66 if (freeze_depth
== 1) {
67 percpu_ref_kill(&q
->q_usage_counter
);
68 blk_mq_run_hw_queues(q
, false);
71 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start
);
73 static void blk_mq_freeze_queue_wait(struct request_queue
*q
)
75 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
79 * Guarantee no request is in use, so we can change any data structure of
80 * the queue afterward.
82 void blk_freeze_queue(struct request_queue
*q
)
85 * In the !blk_mq case we are only calling this to kill the
86 * q_usage_counter, otherwise this increases the freeze depth
87 * and waits for it to return to zero. For this reason there is
88 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
89 * exported to drivers as the only user for unfreeze is blk_mq.
91 blk_mq_freeze_queue_start(q
);
92 blk_mq_freeze_queue_wait(q
);
95 void blk_mq_freeze_queue(struct request_queue
*q
)
98 * ...just an alias to keep freeze and unfreeze actions balanced
99 * in the blk_mq_* namespace
103 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
105 void blk_mq_unfreeze_queue(struct request_queue
*q
)
109 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
110 WARN_ON_ONCE(freeze_depth
< 0);
112 percpu_ref_reinit(&q
->q_usage_counter
);
113 wake_up_all(&q
->mq_freeze_wq
);
116 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
118 void blk_mq_wake_waiters(struct request_queue
*q
)
120 struct blk_mq_hw_ctx
*hctx
;
123 queue_for_each_hw_ctx(q
, hctx
, i
)
124 if (blk_mq_hw_queue_mapped(hctx
))
125 blk_mq_tag_wakeup_all(hctx
->tags
, true);
128 * If we are called because the queue has now been marked as
129 * dying, we need to ensure that processes currently waiting on
130 * the queue are notified as well.
132 wake_up_all(&q
->mq_freeze_wq
);
135 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
137 return blk_mq_has_free_tags(hctx
->tags
);
139 EXPORT_SYMBOL(blk_mq_can_queue
);
141 static void blk_mq_rq_ctx_init(struct request_queue
*q
, struct blk_mq_ctx
*ctx
,
142 struct request
*rq
, int op
,
143 unsigned int op_flags
)
145 if (blk_queue_io_stat(q
))
146 op_flags
|= REQ_IO_STAT
;
148 INIT_LIST_HEAD(&rq
->queuelist
);
149 /* csd/requeue_work/fifo_time is initialized before use */
152 req_set_op_attrs(rq
, op
, op_flags
);
153 /* do not touch atomic flags, it needs atomic ops against the timer */
155 INIT_HLIST_NODE(&rq
->hash
);
156 RB_CLEAR_NODE(&rq
->rb_node
);
159 rq
->start_time
= jiffies
;
160 #ifdef CONFIG_BLK_CGROUP
162 set_start_time_ns(rq
);
163 rq
->io_start_time_ns
= 0;
165 rq
->nr_phys_segments
= 0;
166 #if defined(CONFIG_BLK_DEV_INTEGRITY)
167 rq
->nr_integrity_segments
= 0;
170 /* tag was already set */
180 INIT_LIST_HEAD(&rq
->timeout_list
);
184 rq
->end_io_data
= NULL
;
187 ctx
->rq_dispatched
[rw_is_sync(op
, op_flags
)]++;
190 static struct request
*
191 __blk_mq_alloc_request(struct blk_mq_alloc_data
*data
, int op
, int op_flags
)
196 tag
= blk_mq_get_tag(data
);
197 if (tag
!= BLK_MQ_TAG_FAIL
) {
198 rq
= data
->hctx
->tags
->rqs
[tag
];
200 if (blk_mq_tag_busy(data
->hctx
)) {
201 rq
->cmd_flags
= REQ_MQ_INFLIGHT
;
202 atomic_inc(&data
->hctx
->nr_active
);
206 blk_mq_rq_ctx_init(data
->q
, data
->ctx
, rq
, op
, op_flags
);
213 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
216 struct blk_mq_ctx
*ctx
;
217 struct blk_mq_hw_ctx
*hctx
;
219 struct blk_mq_alloc_data alloc_data
;
222 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
226 ctx
= blk_mq_get_ctx(q
);
227 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
228 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
229 rq
= __blk_mq_alloc_request(&alloc_data
, rw
, 0);
234 return ERR_PTR(-EWOULDBLOCK
);
238 rq
->__sector
= (sector_t
) -1;
239 rq
->bio
= rq
->biotail
= NULL
;
242 EXPORT_SYMBOL(blk_mq_alloc_request
);
244 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
, int rw
,
245 unsigned int flags
, unsigned int hctx_idx
)
247 struct blk_mq_hw_ctx
*hctx
;
248 struct blk_mq_ctx
*ctx
;
250 struct blk_mq_alloc_data alloc_data
;
254 * If the tag allocator sleeps we could get an allocation for a
255 * different hardware context. No need to complicate the low level
256 * allocator for this for the rare use case of a command tied to
259 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
260 return ERR_PTR(-EINVAL
);
262 if (hctx_idx
>= q
->nr_hw_queues
)
263 return ERR_PTR(-EIO
);
265 ret
= blk_queue_enter(q
, true);
270 * Check if the hardware context is actually mapped to anything.
271 * If not tell the caller that it should skip this queue.
273 hctx
= q
->queue_hw_ctx
[hctx_idx
];
274 if (!blk_mq_hw_queue_mapped(hctx
)) {
278 ctx
= __blk_mq_get_ctx(q
, cpumask_first(hctx
->cpumask
));
280 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
281 rq
= __blk_mq_alloc_request(&alloc_data
, rw
, 0);
293 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
295 static void __blk_mq_free_request(struct blk_mq_hw_ctx
*hctx
,
296 struct blk_mq_ctx
*ctx
, struct request
*rq
)
298 const int tag
= rq
->tag
;
299 struct request_queue
*q
= rq
->q
;
301 if (rq
->cmd_flags
& REQ_MQ_INFLIGHT
)
302 atomic_dec(&hctx
->nr_active
);
305 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
306 blk_mq_put_tag(hctx
, ctx
, tag
);
310 void blk_mq_free_hctx_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
312 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
314 ctx
->rq_completed
[rq_is_sync(rq
)]++;
315 __blk_mq_free_request(hctx
, ctx
, rq
);
318 EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request
);
320 void blk_mq_free_request(struct request
*rq
)
322 struct blk_mq_hw_ctx
*hctx
;
323 struct request_queue
*q
= rq
->q
;
325 hctx
= q
->mq_ops
->map_queue(q
, rq
->mq_ctx
->cpu
);
326 blk_mq_free_hctx_request(hctx
, rq
);
328 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
330 inline void __blk_mq_end_request(struct request
*rq
, int error
)
332 blk_account_io_done(rq
);
335 rq
->end_io(rq
, error
);
337 if (unlikely(blk_bidi_rq(rq
)))
338 blk_mq_free_request(rq
->next_rq
);
339 blk_mq_free_request(rq
);
342 EXPORT_SYMBOL(__blk_mq_end_request
);
344 void blk_mq_end_request(struct request
*rq
, int error
)
346 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
348 __blk_mq_end_request(rq
, error
);
350 EXPORT_SYMBOL(blk_mq_end_request
);
352 static void __blk_mq_complete_request_remote(void *data
)
354 struct request
*rq
= data
;
356 rq
->q
->softirq_done_fn(rq
);
359 static void blk_mq_ipi_complete_request(struct request
*rq
)
361 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
365 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
366 rq
->q
->softirq_done_fn(rq
);
371 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
372 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
374 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
375 rq
->csd
.func
= __blk_mq_complete_request_remote
;
378 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
380 rq
->q
->softirq_done_fn(rq
);
385 static void __blk_mq_complete_request(struct request
*rq
)
387 struct request_queue
*q
= rq
->q
;
389 if (!q
->softirq_done_fn
)
390 blk_mq_end_request(rq
, rq
->errors
);
392 blk_mq_ipi_complete_request(rq
);
396 * blk_mq_complete_request - end I/O on a request
397 * @rq: the request being processed
400 * Ends all I/O on a request. It does not handle partial completions.
401 * The actual completion happens out-of-order, through a IPI handler.
403 void blk_mq_complete_request(struct request
*rq
, int error
)
405 struct request_queue
*q
= rq
->q
;
407 if (unlikely(blk_should_fake_timeout(q
)))
409 if (!blk_mark_rq_complete(rq
)) {
411 __blk_mq_complete_request(rq
);
414 EXPORT_SYMBOL(blk_mq_complete_request
);
416 int blk_mq_request_started(struct request
*rq
)
418 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
420 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
422 void blk_mq_start_request(struct request
*rq
)
424 struct request_queue
*q
= rq
->q
;
426 trace_block_rq_issue(q
, rq
);
428 rq
->resid_len
= blk_rq_bytes(rq
);
429 if (unlikely(blk_bidi_rq(rq
)))
430 rq
->next_rq
->resid_len
= blk_rq_bytes(rq
->next_rq
);
435 * Ensure that ->deadline is visible before set the started
436 * flag and clear the completed flag.
438 smp_mb__before_atomic();
441 * Mark us as started and clear complete. Complete might have been
442 * set if requeue raced with timeout, which then marked it as
443 * complete. So be sure to clear complete again when we start
444 * the request, otherwise we'll ignore the completion event.
446 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
447 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
448 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
449 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
451 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
453 * Make sure space for the drain appears. We know we can do
454 * this because max_hw_segments has been adjusted to be one
455 * fewer than the device can handle.
457 rq
->nr_phys_segments
++;
460 EXPORT_SYMBOL(blk_mq_start_request
);
462 static void __blk_mq_requeue_request(struct request
*rq
)
464 struct request_queue
*q
= rq
->q
;
466 trace_block_rq_requeue(q
, rq
);
468 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
469 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
470 rq
->nr_phys_segments
--;
474 void blk_mq_requeue_request(struct request
*rq
)
476 __blk_mq_requeue_request(rq
);
478 BUG_ON(blk_queued_rq(rq
));
479 blk_mq_add_to_requeue_list(rq
, true);
481 EXPORT_SYMBOL(blk_mq_requeue_request
);
483 static void blk_mq_requeue_work(struct work_struct
*work
)
485 struct request_queue
*q
=
486 container_of(work
, struct request_queue
, requeue_work
.work
);
488 struct request
*rq
, *next
;
491 spin_lock_irqsave(&q
->requeue_lock
, flags
);
492 list_splice_init(&q
->requeue_list
, &rq_list
);
493 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
495 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
496 if (!(rq
->cmd_flags
& REQ_SOFTBARRIER
))
499 rq
->cmd_flags
&= ~REQ_SOFTBARRIER
;
500 list_del_init(&rq
->queuelist
);
501 blk_mq_insert_request(rq
, true, false, false);
504 while (!list_empty(&rq_list
)) {
505 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
506 list_del_init(&rq
->queuelist
);
507 blk_mq_insert_request(rq
, false, false, false);
511 * Use the start variant of queue running here, so that running
512 * the requeue work will kick stopped queues.
514 blk_mq_start_hw_queues(q
);
517 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
)
519 struct request_queue
*q
= rq
->q
;
523 * We abuse this flag that is otherwise used by the I/O scheduler to
524 * request head insertation from the workqueue.
526 BUG_ON(rq
->cmd_flags
& REQ_SOFTBARRIER
);
528 spin_lock_irqsave(&q
->requeue_lock
, flags
);
530 rq
->cmd_flags
|= REQ_SOFTBARRIER
;
531 list_add(&rq
->queuelist
, &q
->requeue_list
);
533 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
535 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
537 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
539 void blk_mq_cancel_requeue_work(struct request_queue
*q
)
541 cancel_delayed_work_sync(&q
->requeue_work
);
543 EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work
);
545 void blk_mq_kick_requeue_list(struct request_queue
*q
)
547 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
549 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
551 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
554 kblockd_schedule_delayed_work(&q
->requeue_work
,
555 msecs_to_jiffies(msecs
));
557 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
559 void blk_mq_abort_requeue_list(struct request_queue
*q
)
564 spin_lock_irqsave(&q
->requeue_lock
, flags
);
565 list_splice_init(&q
->requeue_list
, &rq_list
);
566 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
568 while (!list_empty(&rq_list
)) {
571 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
572 list_del_init(&rq
->queuelist
);
574 blk_mq_end_request(rq
, rq
->errors
);
577 EXPORT_SYMBOL(blk_mq_abort_requeue_list
);
579 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
581 if (tag
< tags
->nr_tags
) {
582 prefetch(tags
->rqs
[tag
]);
583 return tags
->rqs
[tag
];
588 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
590 struct blk_mq_timeout_data
{
592 unsigned int next_set
;
595 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
597 struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
598 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
601 * We know that complete is set at this point. If STARTED isn't set
602 * anymore, then the request isn't active and the "timeout" should
603 * just be ignored. This can happen due to the bitflag ordering.
604 * Timeout first checks if STARTED is set, and if it is, assumes
605 * the request is active. But if we race with completion, then
606 * we both flags will get cleared. So check here again, and ignore
607 * a timeout event with a request that isn't active.
609 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
613 ret
= ops
->timeout(req
, reserved
);
617 __blk_mq_complete_request(req
);
619 case BLK_EH_RESET_TIMER
:
621 blk_clear_rq_complete(req
);
623 case BLK_EH_NOT_HANDLED
:
626 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
631 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
632 struct request
*rq
, void *priv
, bool reserved
)
634 struct blk_mq_timeout_data
*data
= priv
;
636 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
638 * If a request wasn't started before the queue was
639 * marked dying, kill it here or it'll go unnoticed.
641 if (unlikely(blk_queue_dying(rq
->q
))) {
643 blk_mq_end_request(rq
, rq
->errors
);
648 if (time_after_eq(jiffies
, rq
->deadline
)) {
649 if (!blk_mark_rq_complete(rq
))
650 blk_mq_rq_timed_out(rq
, reserved
);
651 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
652 data
->next
= rq
->deadline
;
657 static void blk_mq_timeout_work(struct work_struct
*work
)
659 struct request_queue
*q
=
660 container_of(work
, struct request_queue
, timeout_work
);
661 struct blk_mq_timeout_data data
= {
667 /* A deadlock might occur if a request is stuck requiring a
668 * timeout at the same time a queue freeze is waiting
669 * completion, since the timeout code would not be able to
670 * acquire the queue reference here.
672 * That's why we don't use blk_queue_enter here; instead, we use
673 * percpu_ref_tryget directly, because we need to be able to
674 * obtain a reference even in the short window between the queue
675 * starting to freeze, by dropping the first reference in
676 * blk_mq_freeze_queue_start, and the moment the last request is
677 * consumed, marked by the instant q_usage_counter reaches
680 if (!percpu_ref_tryget(&q
->q_usage_counter
))
683 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
686 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
687 mod_timer(&q
->timeout
, data
.next
);
689 struct blk_mq_hw_ctx
*hctx
;
691 queue_for_each_hw_ctx(q
, hctx
, i
) {
692 /* the hctx may be unmapped, so check it here */
693 if (blk_mq_hw_queue_mapped(hctx
))
694 blk_mq_tag_idle(hctx
);
701 * Reverse check our software queue for entries that we could potentially
702 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
703 * too much time checking for merges.
705 static bool blk_mq_attempt_merge(struct request_queue
*q
,
706 struct blk_mq_ctx
*ctx
, struct bio
*bio
)
711 list_for_each_entry_reverse(rq
, &ctx
->rq_list
, queuelist
) {
717 if (!blk_rq_merge_ok(rq
, bio
))
720 el_ret
= blk_try_merge(rq
, bio
);
721 if (el_ret
== ELEVATOR_BACK_MERGE
) {
722 if (bio_attempt_back_merge(q
, rq
, bio
)) {
727 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
728 if (bio_attempt_front_merge(q
, rq
, bio
)) {
739 struct flush_busy_ctx_data
{
740 struct blk_mq_hw_ctx
*hctx
;
741 struct list_head
*list
;
744 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
746 struct flush_busy_ctx_data
*flush_data
= data
;
747 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
748 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
750 sbitmap_clear_bit(sb
, bitnr
);
751 spin_lock(&ctx
->lock
);
752 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
753 spin_unlock(&ctx
->lock
);
758 * Process software queues that have been marked busy, splicing them
759 * to the for-dispatch
761 static void flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
763 struct flush_busy_ctx_data data
= {
768 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
771 static inline unsigned int queued_to_index(unsigned int queued
)
776 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
780 * Run this hardware queue, pulling any software queues mapped to it in.
781 * Note that this function currently has various problems around ordering
782 * of IO. In particular, we'd like FIFO behaviour on handling existing
783 * items on the hctx->dispatch list. Ignore that for now.
785 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
787 struct request_queue
*q
= hctx
->queue
;
790 LIST_HEAD(driver_list
);
791 struct list_head
*dptr
;
794 if (unlikely(test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)))
797 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
798 cpu_online(hctx
->next_cpu
));
803 * Touch any software queue that has pending entries.
805 flush_busy_ctxs(hctx
, &rq_list
);
808 * If we have previous entries on our dispatch list, grab them
809 * and stuff them at the front for more fair dispatch.
811 if (!list_empty_careful(&hctx
->dispatch
)) {
812 spin_lock(&hctx
->lock
);
813 if (!list_empty(&hctx
->dispatch
))
814 list_splice_init(&hctx
->dispatch
, &rq_list
);
815 spin_unlock(&hctx
->lock
);
819 * Start off with dptr being NULL, so we start the first request
820 * immediately, even if we have more pending.
825 * Now process all the entries, sending them to the driver.
828 while (!list_empty(&rq_list
)) {
829 struct blk_mq_queue_data bd
;
832 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
833 list_del_init(&rq
->queuelist
);
837 bd
.last
= list_empty(&rq_list
);
839 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
841 case BLK_MQ_RQ_QUEUE_OK
:
844 case BLK_MQ_RQ_QUEUE_BUSY
:
845 list_add(&rq
->queuelist
, &rq_list
);
846 __blk_mq_requeue_request(rq
);
849 pr_err("blk-mq: bad return on queue: %d\n", ret
);
850 case BLK_MQ_RQ_QUEUE_ERROR
:
852 blk_mq_end_request(rq
, rq
->errors
);
856 if (ret
== BLK_MQ_RQ_QUEUE_BUSY
)
860 * We've done the first request. If we have more than 1
861 * left in the list, set dptr to defer issue.
863 if (!dptr
&& rq_list
.next
!= rq_list
.prev
)
867 hctx
->dispatched
[queued_to_index(queued
)]++;
870 * Any items that need requeuing? Stuff them into hctx->dispatch,
871 * that is where we will continue on next queue run.
873 if (!list_empty(&rq_list
)) {
874 spin_lock(&hctx
->lock
);
875 list_splice(&rq_list
, &hctx
->dispatch
);
876 spin_unlock(&hctx
->lock
);
878 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
879 * it's possible the queue is stopped and restarted again
880 * before this. Queue restart will dispatch requests. And since
881 * requests in rq_list aren't added into hctx->dispatch yet,
882 * the requests in rq_list might get lost.
884 * blk_mq_run_hw_queue() already checks the STOPPED bit
886 blk_mq_run_hw_queue(hctx
, true);
891 * It'd be great if the workqueue API had a way to pass
892 * in a mask and had some smarts for more clever placement.
893 * For now we just round-robin here, switching for every
894 * BLK_MQ_CPU_WORK_BATCH queued items.
896 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
898 if (hctx
->queue
->nr_hw_queues
== 1)
899 return WORK_CPU_UNBOUND
;
901 if (--hctx
->next_cpu_batch
<= 0) {
902 int cpu
= hctx
->next_cpu
, next_cpu
;
904 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
905 if (next_cpu
>= nr_cpu_ids
)
906 next_cpu
= cpumask_first(hctx
->cpumask
);
908 hctx
->next_cpu
= next_cpu
;
909 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
914 return hctx
->next_cpu
;
917 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
919 if (unlikely(test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
) ||
920 !blk_mq_hw_queue_mapped(hctx
)))
923 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
925 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
926 __blk_mq_run_hw_queue(hctx
);
934 kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
);
937 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
939 struct blk_mq_hw_ctx
*hctx
;
942 queue_for_each_hw_ctx(q
, hctx
, i
) {
943 if ((!blk_mq_hctx_has_pending(hctx
) &&
944 list_empty_careful(&hctx
->dispatch
)) ||
945 test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
948 blk_mq_run_hw_queue(hctx
, async
);
951 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
953 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
955 cancel_work(&hctx
->run_work
);
956 cancel_delayed_work(&hctx
->delay_work
);
957 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
959 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
961 void blk_mq_stop_hw_queues(struct request_queue
*q
)
963 struct blk_mq_hw_ctx
*hctx
;
966 queue_for_each_hw_ctx(q
, hctx
, i
)
967 blk_mq_stop_hw_queue(hctx
);
969 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
971 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
973 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
975 blk_mq_run_hw_queue(hctx
, false);
977 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
979 void blk_mq_start_hw_queues(struct request_queue
*q
)
981 struct blk_mq_hw_ctx
*hctx
;
984 queue_for_each_hw_ctx(q
, hctx
, i
)
985 blk_mq_start_hw_queue(hctx
);
987 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
989 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
991 struct blk_mq_hw_ctx
*hctx
;
994 queue_for_each_hw_ctx(q
, hctx
, i
) {
995 if (!test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
998 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
999 blk_mq_run_hw_queue(hctx
, async
);
1002 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1004 static void blk_mq_run_work_fn(struct work_struct
*work
)
1006 struct blk_mq_hw_ctx
*hctx
;
1008 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
);
1010 __blk_mq_run_hw_queue(hctx
);
1013 static void blk_mq_delay_work_fn(struct work_struct
*work
)
1015 struct blk_mq_hw_ctx
*hctx
;
1017 hctx
= container_of(work
, struct blk_mq_hw_ctx
, delay_work
.work
);
1019 if (test_and_clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1020 __blk_mq_run_hw_queue(hctx
);
1023 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1025 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
1028 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1029 &hctx
->delay_work
, msecs_to_jiffies(msecs
));
1031 EXPORT_SYMBOL(blk_mq_delay_queue
);
1033 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1037 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1039 trace_block_rq_insert(hctx
->queue
, rq
);
1042 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1044 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1047 static void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
,
1048 struct request
*rq
, bool at_head
)
1050 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1052 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1053 blk_mq_hctx_mark_pending(hctx
, ctx
);
1056 void blk_mq_insert_request(struct request
*rq
, bool at_head
, bool run_queue
,
1059 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1060 struct request_queue
*q
= rq
->q
;
1061 struct blk_mq_hw_ctx
*hctx
;
1063 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1065 spin_lock(&ctx
->lock
);
1066 __blk_mq_insert_request(hctx
, rq
, at_head
);
1067 spin_unlock(&ctx
->lock
);
1070 blk_mq_run_hw_queue(hctx
, async
);
1073 static void blk_mq_insert_requests(struct request_queue
*q
,
1074 struct blk_mq_ctx
*ctx
,
1075 struct list_head
*list
,
1080 struct blk_mq_hw_ctx
*hctx
;
1082 trace_block_unplug(q
, depth
, !from_schedule
);
1084 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1087 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1090 spin_lock(&ctx
->lock
);
1091 while (!list_empty(list
)) {
1094 rq
= list_first_entry(list
, struct request
, queuelist
);
1095 BUG_ON(rq
->mq_ctx
!= ctx
);
1096 list_del_init(&rq
->queuelist
);
1097 __blk_mq_insert_req_list(hctx
, rq
, false);
1099 blk_mq_hctx_mark_pending(hctx
, ctx
);
1100 spin_unlock(&ctx
->lock
);
1102 blk_mq_run_hw_queue(hctx
, from_schedule
);
1105 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1107 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1108 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1110 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1111 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1112 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1115 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1117 struct blk_mq_ctx
*this_ctx
;
1118 struct request_queue
*this_q
;
1121 LIST_HEAD(ctx_list
);
1124 list_splice_init(&plug
->mq_list
, &list
);
1126 list_sort(NULL
, &list
, plug_ctx_cmp
);
1132 while (!list_empty(&list
)) {
1133 rq
= list_entry_rq(list
.next
);
1134 list_del_init(&rq
->queuelist
);
1136 if (rq
->mq_ctx
!= this_ctx
) {
1138 blk_mq_insert_requests(this_q
, this_ctx
,
1143 this_ctx
= rq
->mq_ctx
;
1149 list_add_tail(&rq
->queuelist
, &ctx_list
);
1153 * If 'this_ctx' is set, we know we have entries to complete
1154 * on 'ctx_list'. Do those.
1157 blk_mq_insert_requests(this_q
, this_ctx
, &ctx_list
, depth
,
1162 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1164 init_request_from_bio(rq
, bio
);
1166 blk_account_io_start(rq
, 1);
1169 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1171 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1172 !blk_queue_nomerges(hctx
->queue
);
1175 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx
*hctx
,
1176 struct blk_mq_ctx
*ctx
,
1177 struct request
*rq
, struct bio
*bio
)
1179 if (!hctx_allow_merges(hctx
) || !bio_mergeable(bio
)) {
1180 blk_mq_bio_to_request(rq
, bio
);
1181 spin_lock(&ctx
->lock
);
1183 __blk_mq_insert_request(hctx
, rq
, false);
1184 spin_unlock(&ctx
->lock
);
1187 struct request_queue
*q
= hctx
->queue
;
1189 spin_lock(&ctx
->lock
);
1190 if (!blk_mq_attempt_merge(q
, ctx
, bio
)) {
1191 blk_mq_bio_to_request(rq
, bio
);
1195 spin_unlock(&ctx
->lock
);
1196 __blk_mq_free_request(hctx
, ctx
, rq
);
1201 struct blk_map_ctx
{
1202 struct blk_mq_hw_ctx
*hctx
;
1203 struct blk_mq_ctx
*ctx
;
1206 static struct request
*blk_mq_map_request(struct request_queue
*q
,
1208 struct blk_map_ctx
*data
)
1210 struct blk_mq_hw_ctx
*hctx
;
1211 struct blk_mq_ctx
*ctx
;
1213 int op
= bio_data_dir(bio
);
1215 struct blk_mq_alloc_data alloc_data
;
1217 blk_queue_enter_live(q
);
1218 ctx
= blk_mq_get_ctx(q
);
1219 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1221 if (rw_is_sync(bio_op(bio
), bio
->bi_opf
))
1222 op_flags
|= REQ_SYNC
;
1224 trace_block_getrq(q
, bio
, op
);
1225 blk_mq_set_alloc_data(&alloc_data
, q
, 0, ctx
, hctx
);
1226 rq
= __blk_mq_alloc_request(&alloc_data
, op
, op_flags
);
1234 static int blk_mq_direct_issue_request(struct request
*rq
, blk_qc_t
*cookie
)
1237 struct request_queue
*q
= rq
->q
;
1238 struct blk_mq_hw_ctx
*hctx
= q
->mq_ops
->map_queue(q
,
1240 struct blk_mq_queue_data bd
= {
1245 blk_qc_t new_cookie
= blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
);
1248 * For OK queue, we are done. For error, kill it. Any other
1249 * error (busy), just add it to our list as we previously
1252 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1253 if (ret
== BLK_MQ_RQ_QUEUE_OK
) {
1254 *cookie
= new_cookie
;
1258 __blk_mq_requeue_request(rq
);
1260 if (ret
== BLK_MQ_RQ_QUEUE_ERROR
) {
1261 *cookie
= BLK_QC_T_NONE
;
1263 blk_mq_end_request(rq
, rq
->errors
);
1271 * Multiple hardware queue variant. This will not use per-process plugs,
1272 * but will attempt to bypass the hctx queueing if we can go straight to
1273 * hardware for SYNC IO.
1275 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1277 const int is_sync
= rw_is_sync(bio_op(bio
), bio
->bi_opf
);
1278 const int is_flush_fua
= bio
->bi_opf
& (REQ_PREFLUSH
| REQ_FUA
);
1279 struct blk_map_ctx data
;
1281 unsigned int request_count
= 0;
1282 struct blk_plug
*plug
;
1283 struct request
*same_queue_rq
= NULL
;
1286 blk_queue_bounce(q
, &bio
);
1288 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1290 return BLK_QC_T_NONE
;
1293 blk_queue_split(q
, &bio
, q
->bio_split
);
1295 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1296 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1297 return BLK_QC_T_NONE
;
1299 rq
= blk_mq_map_request(q
, bio
, &data
);
1301 return BLK_QC_T_NONE
;
1303 cookie
= blk_tag_to_qc_t(rq
->tag
, data
.hctx
->queue_num
);
1305 if (unlikely(is_flush_fua
)) {
1306 blk_mq_bio_to_request(rq
, bio
);
1307 blk_insert_flush(rq
);
1311 plug
= current
->plug
;
1313 * If the driver supports defer issued based on 'last', then
1314 * queue it up like normal since we can potentially save some
1317 if (((plug
&& !blk_queue_nomerges(q
)) || is_sync
) &&
1318 !(data
.hctx
->flags
& BLK_MQ_F_DEFER_ISSUE
)) {
1319 struct request
*old_rq
= NULL
;
1321 blk_mq_bio_to_request(rq
, bio
);
1324 * We do limited pluging. If the bio can be merged, do that.
1325 * Otherwise the existing request in the plug list will be
1326 * issued. So the plug list will have one request at most
1330 * The plug list might get flushed before this. If that
1331 * happens, same_queue_rq is invalid and plug list is
1334 if (same_queue_rq
&& !list_empty(&plug
->mq_list
)) {
1335 old_rq
= same_queue_rq
;
1336 list_del_init(&old_rq
->queuelist
);
1338 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1339 } else /* is_sync */
1341 blk_mq_put_ctx(data
.ctx
);
1344 if (!blk_mq_direct_issue_request(old_rq
, &cookie
))
1346 blk_mq_insert_request(old_rq
, false, true, true);
1350 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1352 * For a SYNC request, send it to the hardware immediately. For
1353 * an ASYNC request, just ensure that we run it later on. The
1354 * latter allows for merging opportunities and more efficient
1358 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1360 blk_mq_put_ctx(data
.ctx
);
1366 * Single hardware queue variant. This will attempt to use any per-process
1367 * plug for merging and IO deferral.
1369 static blk_qc_t
blk_sq_make_request(struct request_queue
*q
, struct bio
*bio
)
1371 const int is_sync
= rw_is_sync(bio_op(bio
), bio
->bi_opf
);
1372 const int is_flush_fua
= bio
->bi_opf
& (REQ_PREFLUSH
| REQ_FUA
);
1373 struct blk_plug
*plug
;
1374 unsigned int request_count
= 0;
1375 struct blk_map_ctx data
;
1379 blk_queue_bounce(q
, &bio
);
1381 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1383 return BLK_QC_T_NONE
;
1386 blk_queue_split(q
, &bio
, q
->bio_split
);
1388 if (!is_flush_fua
&& !blk_queue_nomerges(q
)) {
1389 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1390 return BLK_QC_T_NONE
;
1392 request_count
= blk_plug_queued_count(q
);
1394 rq
= blk_mq_map_request(q
, bio
, &data
);
1396 return BLK_QC_T_NONE
;
1398 cookie
= blk_tag_to_qc_t(rq
->tag
, data
.hctx
->queue_num
);
1400 if (unlikely(is_flush_fua
)) {
1401 blk_mq_bio_to_request(rq
, bio
);
1402 blk_insert_flush(rq
);
1407 * A task plug currently exists. Since this is completely lockless,
1408 * utilize that to temporarily store requests until the task is
1409 * either done or scheduled away.
1411 plug
= current
->plug
;
1413 blk_mq_bio_to_request(rq
, bio
);
1415 trace_block_plug(q
);
1417 blk_mq_put_ctx(data
.ctx
);
1419 if (request_count
>= BLK_MAX_REQUEST_COUNT
) {
1420 blk_flush_plug_list(plug
, false);
1421 trace_block_plug(q
);
1424 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1428 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1430 * For a SYNC request, send it to the hardware immediately. For
1431 * an ASYNC request, just ensure that we run it later on. The
1432 * latter allows for merging opportunities and more efficient
1436 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1439 blk_mq_put_ctx(data
.ctx
);
1444 * Default mapping to a software queue, since we use one per CPU.
1446 struct blk_mq_hw_ctx
*blk_mq_map_queue(struct request_queue
*q
, const int cpu
)
1448 return q
->queue_hw_ctx
[q
->mq_map
[cpu
]];
1450 EXPORT_SYMBOL(blk_mq_map_queue
);
1452 static void blk_mq_free_rq_map(struct blk_mq_tag_set
*set
,
1453 struct blk_mq_tags
*tags
, unsigned int hctx_idx
)
1457 if (tags
->rqs
&& set
->ops
->exit_request
) {
1460 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1463 set
->ops
->exit_request(set
->driver_data
, tags
->rqs
[i
],
1465 tags
->rqs
[i
] = NULL
;
1469 while (!list_empty(&tags
->page_list
)) {
1470 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1471 list_del_init(&page
->lru
);
1473 * Remove kmemleak object previously allocated in
1474 * blk_mq_init_rq_map().
1476 kmemleak_free(page_address(page
));
1477 __free_pages(page
, page
->private);
1482 blk_mq_free_tags(tags
);
1485 static size_t order_to_size(unsigned int order
)
1487 return (size_t)PAGE_SIZE
<< order
;
1490 static struct blk_mq_tags
*blk_mq_init_rq_map(struct blk_mq_tag_set
*set
,
1491 unsigned int hctx_idx
)
1493 struct blk_mq_tags
*tags
;
1494 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1495 size_t rq_size
, left
;
1497 tags
= blk_mq_init_tags(set
->queue_depth
, set
->reserved_tags
,
1499 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1503 INIT_LIST_HEAD(&tags
->page_list
);
1505 tags
->rqs
= kzalloc_node(set
->queue_depth
* sizeof(struct request
*),
1506 GFP_KERNEL
| __GFP_NOWARN
| __GFP_NORETRY
,
1509 blk_mq_free_tags(tags
);
1514 * rq_size is the size of the request plus driver payload, rounded
1515 * to the cacheline size
1517 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1519 left
= rq_size
* set
->queue_depth
;
1521 for (i
= 0; i
< set
->queue_depth
; ) {
1522 int this_order
= max_order
;
1527 while (this_order
&& left
< order_to_size(this_order
- 1))
1531 page
= alloc_pages_node(set
->numa_node
,
1532 GFP_KERNEL
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1538 if (order_to_size(this_order
) < rq_size
)
1545 page
->private = this_order
;
1546 list_add_tail(&page
->lru
, &tags
->page_list
);
1548 p
= page_address(page
);
1550 * Allow kmemleak to scan these pages as they contain pointers
1551 * to additional allocations like via ops->init_request().
1553 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_KERNEL
);
1554 entries_per_page
= order_to_size(this_order
) / rq_size
;
1555 to_do
= min(entries_per_page
, set
->queue_depth
- i
);
1556 left
-= to_do
* rq_size
;
1557 for (j
= 0; j
< to_do
; j
++) {
1559 if (set
->ops
->init_request
) {
1560 if (set
->ops
->init_request(set
->driver_data
,
1561 tags
->rqs
[i
], hctx_idx
, i
,
1563 tags
->rqs
[i
] = NULL
;
1575 blk_mq_free_rq_map(set
, tags
, hctx_idx
);
1580 * 'cpu' is going away. splice any existing rq_list entries from this
1581 * software queue to the hw queue dispatch list, and ensure that it
1584 static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx
*hctx
, int cpu
)
1586 struct blk_mq_ctx
*ctx
;
1589 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1591 spin_lock(&ctx
->lock
);
1592 if (!list_empty(&ctx
->rq_list
)) {
1593 list_splice_init(&ctx
->rq_list
, &tmp
);
1594 blk_mq_hctx_clear_pending(hctx
, ctx
);
1596 spin_unlock(&ctx
->lock
);
1598 if (list_empty(&tmp
))
1601 spin_lock(&hctx
->lock
);
1602 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1603 spin_unlock(&hctx
->lock
);
1605 blk_mq_run_hw_queue(hctx
, true);
1609 static int blk_mq_hctx_notify(void *data
, unsigned long action
,
1612 struct blk_mq_hw_ctx
*hctx
= data
;
1614 if (action
== CPU_DEAD
|| action
== CPU_DEAD_FROZEN
)
1615 return blk_mq_hctx_cpu_offline(hctx
, cpu
);
1618 * In case of CPU online, tags may be reallocated
1619 * in blk_mq_map_swqueue() after mapping is updated.
1625 /* hctx->ctxs will be freed in queue's release handler */
1626 static void blk_mq_exit_hctx(struct request_queue
*q
,
1627 struct blk_mq_tag_set
*set
,
1628 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1630 unsigned flush_start_tag
= set
->queue_depth
;
1632 blk_mq_tag_idle(hctx
);
1634 if (set
->ops
->exit_request
)
1635 set
->ops
->exit_request(set
->driver_data
,
1636 hctx
->fq
->flush_rq
, hctx_idx
,
1637 flush_start_tag
+ hctx_idx
);
1639 if (set
->ops
->exit_hctx
)
1640 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1642 blk_mq_unregister_cpu_notifier(&hctx
->cpu_notifier
);
1643 blk_free_flush_queue(hctx
->fq
);
1644 sbitmap_free(&hctx
->ctx_map
);
1647 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1648 struct blk_mq_tag_set
*set
, int nr_queue
)
1650 struct blk_mq_hw_ctx
*hctx
;
1653 queue_for_each_hw_ctx(q
, hctx
, i
) {
1656 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1660 static void blk_mq_free_hw_queues(struct request_queue
*q
,
1661 struct blk_mq_tag_set
*set
)
1663 struct blk_mq_hw_ctx
*hctx
;
1666 queue_for_each_hw_ctx(q
, hctx
, i
)
1667 free_cpumask_var(hctx
->cpumask
);
1670 static int blk_mq_init_hctx(struct request_queue
*q
,
1671 struct blk_mq_tag_set
*set
,
1672 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1675 unsigned flush_start_tag
= set
->queue_depth
;
1677 node
= hctx
->numa_node
;
1678 if (node
== NUMA_NO_NODE
)
1679 node
= hctx
->numa_node
= set
->numa_node
;
1681 INIT_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1682 INIT_DELAYED_WORK(&hctx
->delay_work
, blk_mq_delay_work_fn
);
1683 spin_lock_init(&hctx
->lock
);
1684 INIT_LIST_HEAD(&hctx
->dispatch
);
1686 hctx
->queue_num
= hctx_idx
;
1687 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1689 blk_mq_init_cpu_notifier(&hctx
->cpu_notifier
,
1690 blk_mq_hctx_notify
, hctx
);
1691 blk_mq_register_cpu_notifier(&hctx
->cpu_notifier
);
1693 hctx
->tags
= set
->tags
[hctx_idx
];
1696 * Allocate space for all possible cpus to avoid allocation at
1699 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1702 goto unregister_cpu_notifier
;
1704 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
1710 if (set
->ops
->init_hctx
&&
1711 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1714 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
1718 if (set
->ops
->init_request
&&
1719 set
->ops
->init_request(set
->driver_data
,
1720 hctx
->fq
->flush_rq
, hctx_idx
,
1721 flush_start_tag
+ hctx_idx
, node
))
1729 if (set
->ops
->exit_hctx
)
1730 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1732 sbitmap_free(&hctx
->ctx_map
);
1735 unregister_cpu_notifier
:
1736 blk_mq_unregister_cpu_notifier(&hctx
->cpu_notifier
);
1741 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
1742 unsigned int nr_hw_queues
)
1746 for_each_possible_cpu(i
) {
1747 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1748 struct blk_mq_hw_ctx
*hctx
;
1750 memset(__ctx
, 0, sizeof(*__ctx
));
1752 spin_lock_init(&__ctx
->lock
);
1753 INIT_LIST_HEAD(&__ctx
->rq_list
);
1756 /* If the cpu isn't online, the cpu is mapped to first hctx */
1760 hctx
= q
->mq_ops
->map_queue(q
, i
);
1763 * Set local node, IFF we have more than one hw queue. If
1764 * not, we remain on the home node of the device
1766 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
1767 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
1771 static void blk_mq_map_swqueue(struct request_queue
*q
,
1772 const struct cpumask
*online_mask
)
1775 struct blk_mq_hw_ctx
*hctx
;
1776 struct blk_mq_ctx
*ctx
;
1777 struct blk_mq_tag_set
*set
= q
->tag_set
;
1780 * Avoid others reading imcomplete hctx->cpumask through sysfs
1782 mutex_lock(&q
->sysfs_lock
);
1784 queue_for_each_hw_ctx(q
, hctx
, i
) {
1785 cpumask_clear(hctx
->cpumask
);
1790 * Map software to hardware queues
1792 for_each_possible_cpu(i
) {
1793 /* If the cpu isn't online, the cpu is mapped to first hctx */
1794 if (!cpumask_test_cpu(i
, online_mask
))
1797 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1798 hctx
= q
->mq_ops
->map_queue(q
, i
);
1800 cpumask_set_cpu(i
, hctx
->cpumask
);
1801 ctx
->index_hw
= hctx
->nr_ctx
;
1802 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
1805 mutex_unlock(&q
->sysfs_lock
);
1807 queue_for_each_hw_ctx(q
, hctx
, i
) {
1809 * If no software queues are mapped to this hardware queue,
1810 * disable it and free the request entries.
1812 if (!hctx
->nr_ctx
) {
1814 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
1815 set
->tags
[i
] = NULL
;
1821 /* unmapped hw queue can be remapped after CPU topo changed */
1823 set
->tags
[i
] = blk_mq_init_rq_map(set
, i
);
1824 hctx
->tags
= set
->tags
[i
];
1825 WARN_ON(!hctx
->tags
);
1827 cpumask_copy(hctx
->tags
->cpumask
, hctx
->cpumask
);
1829 * Set the map size to the number of mapped software queues.
1830 * This is more accurate and more efficient than looping
1831 * over all possibly mapped software queues.
1833 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
1836 * Initialize batch roundrobin counts
1838 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
1839 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1843 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
1845 struct blk_mq_hw_ctx
*hctx
;
1848 queue_for_each_hw_ctx(q
, hctx
, i
) {
1850 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
1852 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
1856 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
1858 struct request_queue
*q
;
1860 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
1861 blk_mq_freeze_queue(q
);
1862 queue_set_hctx_shared(q
, shared
);
1863 blk_mq_unfreeze_queue(q
);
1867 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
1869 struct blk_mq_tag_set
*set
= q
->tag_set
;
1871 mutex_lock(&set
->tag_list_lock
);
1872 list_del_init(&q
->tag_set_list
);
1873 if (list_is_singular(&set
->tag_list
)) {
1874 /* just transitioned to unshared */
1875 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
1876 /* update existing queue */
1877 blk_mq_update_tag_set_depth(set
, false);
1879 mutex_unlock(&set
->tag_list_lock
);
1882 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
1883 struct request_queue
*q
)
1887 mutex_lock(&set
->tag_list_lock
);
1889 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
1890 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1891 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
1892 /* update existing queue */
1893 blk_mq_update_tag_set_depth(set
, true);
1895 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
1896 queue_set_hctx_shared(q
, true);
1897 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
1899 mutex_unlock(&set
->tag_list_lock
);
1903 * It is the actual release handler for mq, but we do it from
1904 * request queue's release handler for avoiding use-after-free
1905 * and headache because q->mq_kobj shouldn't have been introduced,
1906 * but we can't group ctx/kctx kobj without it.
1908 void blk_mq_release(struct request_queue
*q
)
1910 struct blk_mq_hw_ctx
*hctx
;
1913 /* hctx kobj stays in hctx */
1914 queue_for_each_hw_ctx(q
, hctx
, i
) {
1924 kfree(q
->queue_hw_ctx
);
1926 /* ctx kobj stays in queue_ctx */
1927 free_percpu(q
->queue_ctx
);
1930 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
1932 struct request_queue
*uninit_q
, *q
;
1934 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
1936 return ERR_PTR(-ENOMEM
);
1938 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
1940 blk_cleanup_queue(uninit_q
);
1944 EXPORT_SYMBOL(blk_mq_init_queue
);
1946 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
1947 struct request_queue
*q
)
1950 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
1952 blk_mq_sysfs_unregister(q
);
1953 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
1959 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
1960 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
1965 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
1972 atomic_set(&hctxs
[i
]->nr_active
, 0);
1973 hctxs
[i
]->numa_node
= node
;
1974 hctxs
[i
]->queue_num
= i
;
1976 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
1977 free_cpumask_var(hctxs
[i
]->cpumask
);
1982 blk_mq_hctx_kobj_init(hctxs
[i
]);
1984 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
1985 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
1989 blk_mq_free_rq_map(set
, hctx
->tags
, j
);
1990 set
->tags
[j
] = NULL
;
1992 blk_mq_exit_hctx(q
, set
, hctx
, j
);
1993 free_cpumask_var(hctx
->cpumask
);
1994 kobject_put(&hctx
->kobj
);
2001 q
->nr_hw_queues
= i
;
2002 blk_mq_sysfs_register(q
);
2005 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2006 struct request_queue
*q
)
2008 /* mark the queue as mq asap */
2009 q
->mq_ops
= set
->ops
;
2011 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2015 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2016 GFP_KERNEL
, set
->numa_node
);
2017 if (!q
->queue_hw_ctx
)
2020 q
->mq_map
= blk_mq_make_queue_map(set
);
2024 blk_mq_realloc_hw_ctxs(set
, q
);
2025 if (!q
->nr_hw_queues
)
2028 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2029 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2031 q
->nr_queues
= nr_cpu_ids
;
2033 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2035 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2036 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2038 q
->sg_reserved_size
= INT_MAX
;
2040 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2041 INIT_LIST_HEAD(&q
->requeue_list
);
2042 spin_lock_init(&q
->requeue_lock
);
2044 if (q
->nr_hw_queues
> 1)
2045 blk_queue_make_request(q
, blk_mq_make_request
);
2047 blk_queue_make_request(q
, blk_sq_make_request
);
2050 * Do this after blk_queue_make_request() overrides it...
2052 q
->nr_requests
= set
->queue_depth
;
2054 if (set
->ops
->complete
)
2055 blk_queue_softirq_done(q
, set
->ops
->complete
);
2057 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2060 mutex_lock(&all_q_mutex
);
2062 list_add_tail(&q
->all_q_node
, &all_q_list
);
2063 blk_mq_add_queue_tag_set(set
, q
);
2064 blk_mq_map_swqueue(q
, cpu_online_mask
);
2066 mutex_unlock(&all_q_mutex
);
2074 kfree(q
->queue_hw_ctx
);
2076 free_percpu(q
->queue_ctx
);
2079 return ERR_PTR(-ENOMEM
);
2081 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2083 void blk_mq_free_queue(struct request_queue
*q
)
2085 struct blk_mq_tag_set
*set
= q
->tag_set
;
2087 mutex_lock(&all_q_mutex
);
2088 list_del_init(&q
->all_q_node
);
2089 mutex_unlock(&all_q_mutex
);
2091 blk_mq_del_queue_tag_set(q
);
2093 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2094 blk_mq_free_hw_queues(q
, set
);
2097 /* Basically redo blk_mq_init_queue with queue frozen */
2098 static void blk_mq_queue_reinit(struct request_queue
*q
,
2099 const struct cpumask
*online_mask
)
2101 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2103 blk_mq_sysfs_unregister(q
);
2105 blk_mq_update_queue_map(q
->mq_map
, q
->nr_hw_queues
, online_mask
);
2108 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2109 * we should change hctx numa_node according to new topology (this
2110 * involves free and re-allocate memory, worthy doing?)
2113 blk_mq_map_swqueue(q
, online_mask
);
2115 blk_mq_sysfs_register(q
);
2118 static int blk_mq_queue_reinit_notify(struct notifier_block
*nb
,
2119 unsigned long action
, void *hcpu
)
2121 struct request_queue
*q
;
2122 int cpu
= (unsigned long)hcpu
;
2124 * New online cpumask which is going to be set in this hotplug event.
2125 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2126 * one-by-one and dynamically allocating this could result in a failure.
2128 static struct cpumask online_new
;
2131 * Before hotadded cpu starts handling requests, new mappings must
2132 * be established. Otherwise, these requests in hw queue might
2133 * never be dispatched.
2135 * For example, there is a single hw queue (hctx) and two CPU queues
2136 * (ctx0 for CPU0, and ctx1 for CPU1).
2138 * Now CPU1 is just onlined and a request is inserted into
2139 * ctx1->rq_list and set bit0 in pending bitmap as ctx1->index_hw is
2142 * And then while running hw queue, flush_busy_ctxs() finds bit0 is
2143 * set in pending bitmap and tries to retrieve requests in
2144 * hctx->ctxs[0]->rq_list. But htx->ctxs[0] is a pointer to ctx0,
2145 * so the request in ctx1->rq_list is ignored.
2147 switch (action
& ~CPU_TASKS_FROZEN
) {
2149 case CPU_UP_CANCELED
:
2150 cpumask_copy(&online_new
, cpu_online_mask
);
2152 case CPU_UP_PREPARE
:
2153 cpumask_copy(&online_new
, cpu_online_mask
);
2154 cpumask_set_cpu(cpu
, &online_new
);
2160 mutex_lock(&all_q_mutex
);
2163 * We need to freeze and reinit all existing queues. Freezing
2164 * involves synchronous wait for an RCU grace period and doing it
2165 * one by one may take a long time. Start freezing all queues in
2166 * one swoop and then wait for the completions so that freezing can
2167 * take place in parallel.
2169 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2170 blk_mq_freeze_queue_start(q
);
2171 list_for_each_entry(q
, &all_q_list
, all_q_node
) {
2172 blk_mq_freeze_queue_wait(q
);
2175 * timeout handler can't touch hw queue during the
2178 del_timer_sync(&q
->timeout
);
2181 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2182 blk_mq_queue_reinit(q
, &online_new
);
2184 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2185 blk_mq_unfreeze_queue(q
);
2187 mutex_unlock(&all_q_mutex
);
2191 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2195 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2196 set
->tags
[i
] = blk_mq_init_rq_map(set
, i
);
2205 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
2211 * Allocate the request maps associated with this tag_set. Note that this
2212 * may reduce the depth asked for, if memory is tight. set->queue_depth
2213 * will be updated to reflect the allocated depth.
2215 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2220 depth
= set
->queue_depth
;
2222 err
= __blk_mq_alloc_rq_maps(set
);
2226 set
->queue_depth
>>= 1;
2227 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2231 } while (set
->queue_depth
);
2233 if (!set
->queue_depth
|| err
) {
2234 pr_err("blk-mq: failed to allocate request map\n");
2238 if (depth
!= set
->queue_depth
)
2239 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2240 depth
, set
->queue_depth
);
2245 struct cpumask
*blk_mq_tags_cpumask(struct blk_mq_tags
*tags
)
2247 return tags
->cpumask
;
2249 EXPORT_SYMBOL_GPL(blk_mq_tags_cpumask
);
2252 * Alloc a tag set to be associated with one or more request queues.
2253 * May fail with EINVAL for various error conditions. May adjust the
2254 * requested depth down, if if it too large. In that case, the set
2255 * value will be stored in set->queue_depth.
2257 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2259 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2261 if (!set
->nr_hw_queues
)
2263 if (!set
->queue_depth
)
2265 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2268 if (!set
->ops
->queue_rq
|| !set
->ops
->map_queue
)
2271 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2272 pr_info("blk-mq: reduced tag depth to %u\n",
2274 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2278 * If a crashdump is active, then we are potentially in a very
2279 * memory constrained environment. Limit us to 1 queue and
2280 * 64 tags to prevent using too much memory.
2282 if (is_kdump_kernel()) {
2283 set
->nr_hw_queues
= 1;
2284 set
->queue_depth
= min(64U, set
->queue_depth
);
2287 * There is no use for more h/w queues than cpus.
2289 if (set
->nr_hw_queues
> nr_cpu_ids
)
2290 set
->nr_hw_queues
= nr_cpu_ids
;
2292 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2293 GFP_KERNEL
, set
->numa_node
);
2297 if (blk_mq_alloc_rq_maps(set
))
2300 mutex_init(&set
->tag_list_lock
);
2301 INIT_LIST_HEAD(&set
->tag_list
);
2309 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2311 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2315 for (i
= 0; i
< nr_cpu_ids
; i
++) {
2317 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
2323 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2325 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2327 struct blk_mq_tag_set
*set
= q
->tag_set
;
2328 struct blk_mq_hw_ctx
*hctx
;
2331 if (!set
|| nr
> set
->queue_depth
)
2335 queue_for_each_hw_ctx(q
, hctx
, i
) {
2338 ret
= blk_mq_tag_update_depth(hctx
->tags
, nr
);
2344 q
->nr_requests
= nr
;
2349 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2351 struct request_queue
*q
;
2353 if (nr_hw_queues
> nr_cpu_ids
)
2354 nr_hw_queues
= nr_cpu_ids
;
2355 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2358 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2359 blk_mq_freeze_queue(q
);
2361 set
->nr_hw_queues
= nr_hw_queues
;
2362 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2363 blk_mq_realloc_hw_ctxs(set
, q
);
2365 if (q
->nr_hw_queues
> 1)
2366 blk_queue_make_request(q
, blk_mq_make_request
);
2368 blk_queue_make_request(q
, blk_sq_make_request
);
2370 blk_mq_queue_reinit(q
, cpu_online_mask
);
2373 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2374 blk_mq_unfreeze_queue(q
);
2376 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2378 void blk_mq_disable_hotplug(void)
2380 mutex_lock(&all_q_mutex
);
2383 void blk_mq_enable_hotplug(void)
2385 mutex_unlock(&all_q_mutex
);
2388 static int __init
blk_mq_init(void)
2392 hotcpu_notifier(blk_mq_queue_reinit_notify
, 0);
2396 subsys_initcall(blk_mq_init
);