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>
26 #include <trace/events/block.h>
28 #include <linux/blk-mq.h>
31 #include "blk-mq-tag.h"
33 static DEFINE_MUTEX(all_q_mutex
);
34 static LIST_HEAD(all_q_list
);
36 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
);
39 * Check if any of the ctx's have pending work in this hardware queue
41 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
45 for (i
= 0; i
< hctx
->ctx_map
.size
; i
++)
46 if (hctx
->ctx_map
.map
[i
].word
)
52 static inline struct blk_align_bitmap
*get_bm(struct blk_mq_hw_ctx
*hctx
,
53 struct blk_mq_ctx
*ctx
)
55 return &hctx
->ctx_map
.map
[ctx
->index_hw
/ hctx
->ctx_map
.bits_per_word
];
58 #define CTX_TO_BIT(hctx, ctx) \
59 ((ctx)->index_hw & ((hctx)->ctx_map.bits_per_word - 1))
62 * Mark this ctx as having pending work in this hardware queue
64 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
65 struct blk_mq_ctx
*ctx
)
67 struct blk_align_bitmap
*bm
= get_bm(hctx
, ctx
);
69 if (!test_bit(CTX_TO_BIT(hctx
, ctx
), &bm
->word
))
70 set_bit(CTX_TO_BIT(hctx
, ctx
), &bm
->word
);
73 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
74 struct blk_mq_ctx
*ctx
)
76 struct blk_align_bitmap
*bm
= get_bm(hctx
, ctx
);
78 clear_bit(CTX_TO_BIT(hctx
, ctx
), &bm
->word
);
81 void blk_mq_freeze_queue_start(struct request_queue
*q
)
85 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
86 if (freeze_depth
== 1) {
87 percpu_ref_kill(&q
->q_usage_counter
);
88 blk_mq_run_hw_queues(q
, false);
91 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start
);
93 static void blk_mq_freeze_queue_wait(struct request_queue
*q
)
95 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
99 * Guarantee no request is in use, so we can change any data structure of
100 * the queue afterward.
102 void blk_freeze_queue(struct request_queue
*q
)
105 * In the !blk_mq case we are only calling this to kill the
106 * q_usage_counter, otherwise this increases the freeze depth
107 * and waits for it to return to zero. For this reason there is
108 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
109 * exported to drivers as the only user for unfreeze is blk_mq.
111 blk_mq_freeze_queue_start(q
);
112 blk_mq_freeze_queue_wait(q
);
115 void blk_mq_freeze_queue(struct request_queue
*q
)
118 * ...just an alias to keep freeze and unfreeze actions balanced
119 * in the blk_mq_* namespace
123 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
125 void blk_mq_unfreeze_queue(struct request_queue
*q
)
129 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
130 WARN_ON_ONCE(freeze_depth
< 0);
132 percpu_ref_reinit(&q
->q_usage_counter
);
133 wake_up_all(&q
->mq_freeze_wq
);
136 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
138 void blk_mq_wake_waiters(struct request_queue
*q
)
140 struct blk_mq_hw_ctx
*hctx
;
143 queue_for_each_hw_ctx(q
, hctx
, i
)
144 if (blk_mq_hw_queue_mapped(hctx
))
145 blk_mq_tag_wakeup_all(hctx
->tags
, true);
148 * If we are called because the queue has now been marked as
149 * dying, we need to ensure that processes currently waiting on
150 * the queue are notified as well.
152 wake_up_all(&q
->mq_freeze_wq
);
155 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
157 return blk_mq_has_free_tags(hctx
->tags
);
159 EXPORT_SYMBOL(blk_mq_can_queue
);
161 static void blk_mq_rq_ctx_init(struct request_queue
*q
, struct blk_mq_ctx
*ctx
,
162 struct request
*rq
, int op
,
163 unsigned int op_flags
)
165 if (blk_queue_io_stat(q
))
166 op_flags
|= REQ_IO_STAT
;
168 INIT_LIST_HEAD(&rq
->queuelist
);
169 /* csd/requeue_work/fifo_time is initialized before use */
172 req_set_op_attrs(rq
, op
, op_flags
);
173 /* do not touch atomic flags, it needs atomic ops against the timer */
175 INIT_HLIST_NODE(&rq
->hash
);
176 RB_CLEAR_NODE(&rq
->rb_node
);
179 rq
->start_time
= jiffies
;
180 #ifdef CONFIG_BLK_CGROUP
182 set_start_time_ns(rq
);
183 rq
->io_start_time_ns
= 0;
185 rq
->nr_phys_segments
= 0;
186 #if defined(CONFIG_BLK_DEV_INTEGRITY)
187 rq
->nr_integrity_segments
= 0;
190 /* tag was already set */
200 INIT_LIST_HEAD(&rq
->timeout_list
);
204 rq
->end_io_data
= NULL
;
207 ctx
->rq_dispatched
[rw_is_sync(op
, op_flags
)]++;
210 static struct request
*
211 __blk_mq_alloc_request(struct blk_mq_alloc_data
*data
, int op
, int op_flags
)
216 tag
= blk_mq_get_tag(data
);
217 if (tag
!= BLK_MQ_TAG_FAIL
) {
218 rq
= data
->hctx
->tags
->rqs
[tag
];
220 if (blk_mq_tag_busy(data
->hctx
)) {
221 rq
->cmd_flags
= REQ_MQ_INFLIGHT
;
222 atomic_inc(&data
->hctx
->nr_active
);
226 blk_mq_rq_ctx_init(data
->q
, data
->ctx
, rq
, op
, op_flags
);
233 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
236 struct blk_mq_ctx
*ctx
;
237 struct blk_mq_hw_ctx
*hctx
;
239 struct blk_mq_alloc_data alloc_data
;
242 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
246 ctx
= blk_mq_get_ctx(q
);
247 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
248 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
250 rq
= __blk_mq_alloc_request(&alloc_data
, rw
, 0);
251 if (!rq
&& !(flags
& BLK_MQ_REQ_NOWAIT
)) {
252 __blk_mq_run_hw_queue(hctx
);
255 ctx
= blk_mq_get_ctx(q
);
256 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
257 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
258 rq
= __blk_mq_alloc_request(&alloc_data
, rw
, 0);
259 ctx
= alloc_data
.ctx
;
264 return ERR_PTR(-EWOULDBLOCK
);
268 EXPORT_SYMBOL(blk_mq_alloc_request
);
270 static void __blk_mq_free_request(struct blk_mq_hw_ctx
*hctx
,
271 struct blk_mq_ctx
*ctx
, struct request
*rq
)
273 const int tag
= rq
->tag
;
274 struct request_queue
*q
= rq
->q
;
276 if (rq
->cmd_flags
& REQ_MQ_INFLIGHT
)
277 atomic_dec(&hctx
->nr_active
);
280 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
281 blk_mq_put_tag(hctx
, tag
, &ctx
->last_tag
);
285 void blk_mq_free_hctx_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
287 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
289 ctx
->rq_completed
[rq_is_sync(rq
)]++;
290 __blk_mq_free_request(hctx
, ctx
, rq
);
293 EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request
);
295 void blk_mq_free_request(struct request
*rq
)
297 struct blk_mq_hw_ctx
*hctx
;
298 struct request_queue
*q
= rq
->q
;
300 hctx
= q
->mq_ops
->map_queue(q
, rq
->mq_ctx
->cpu
);
301 blk_mq_free_hctx_request(hctx
, rq
);
303 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
305 inline void __blk_mq_end_request(struct request
*rq
, int error
)
307 blk_account_io_done(rq
);
310 rq
->end_io(rq
, error
);
312 if (unlikely(blk_bidi_rq(rq
)))
313 blk_mq_free_request(rq
->next_rq
);
314 blk_mq_free_request(rq
);
317 EXPORT_SYMBOL(__blk_mq_end_request
);
319 void blk_mq_end_request(struct request
*rq
, int error
)
321 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
323 __blk_mq_end_request(rq
, error
);
325 EXPORT_SYMBOL(blk_mq_end_request
);
327 static void __blk_mq_complete_request_remote(void *data
)
329 struct request
*rq
= data
;
331 rq
->q
->softirq_done_fn(rq
);
334 static void blk_mq_ipi_complete_request(struct request
*rq
)
336 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
340 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
341 rq
->q
->softirq_done_fn(rq
);
346 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
347 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
349 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
350 rq
->csd
.func
= __blk_mq_complete_request_remote
;
353 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
355 rq
->q
->softirq_done_fn(rq
);
360 static void __blk_mq_complete_request(struct request
*rq
)
362 struct request_queue
*q
= rq
->q
;
364 if (!q
->softirq_done_fn
)
365 blk_mq_end_request(rq
, rq
->errors
);
367 blk_mq_ipi_complete_request(rq
);
371 * blk_mq_complete_request - end I/O on a request
372 * @rq: the request being processed
375 * Ends all I/O on a request. It does not handle partial completions.
376 * The actual completion happens out-of-order, through a IPI handler.
378 void blk_mq_complete_request(struct request
*rq
, int error
)
380 struct request_queue
*q
= rq
->q
;
382 if (unlikely(blk_should_fake_timeout(q
)))
384 if (!blk_mark_rq_complete(rq
)) {
386 __blk_mq_complete_request(rq
);
389 EXPORT_SYMBOL(blk_mq_complete_request
);
391 int blk_mq_request_started(struct request
*rq
)
393 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
395 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
397 void blk_mq_start_request(struct request
*rq
)
399 struct request_queue
*q
= rq
->q
;
401 trace_block_rq_issue(q
, rq
);
403 rq
->resid_len
= blk_rq_bytes(rq
);
404 if (unlikely(blk_bidi_rq(rq
)))
405 rq
->next_rq
->resid_len
= blk_rq_bytes(rq
->next_rq
);
410 * Ensure that ->deadline is visible before set the started
411 * flag and clear the completed flag.
413 smp_mb__before_atomic();
416 * Mark us as started and clear complete. Complete might have been
417 * set if requeue raced with timeout, which then marked it as
418 * complete. So be sure to clear complete again when we start
419 * the request, otherwise we'll ignore the completion event.
421 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
422 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
423 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
424 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
426 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
428 * Make sure space for the drain appears. We know we can do
429 * this because max_hw_segments has been adjusted to be one
430 * fewer than the device can handle.
432 rq
->nr_phys_segments
++;
435 EXPORT_SYMBOL(blk_mq_start_request
);
437 static void __blk_mq_requeue_request(struct request
*rq
)
439 struct request_queue
*q
= rq
->q
;
441 trace_block_rq_requeue(q
, rq
);
443 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
444 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
445 rq
->nr_phys_segments
--;
449 void blk_mq_requeue_request(struct request
*rq
)
451 __blk_mq_requeue_request(rq
);
453 BUG_ON(blk_queued_rq(rq
));
454 blk_mq_add_to_requeue_list(rq
, true);
456 EXPORT_SYMBOL(blk_mq_requeue_request
);
458 static void blk_mq_requeue_work(struct work_struct
*work
)
460 struct request_queue
*q
=
461 container_of(work
, struct request_queue
, requeue_work
);
463 struct request
*rq
, *next
;
466 spin_lock_irqsave(&q
->requeue_lock
, flags
);
467 list_splice_init(&q
->requeue_list
, &rq_list
);
468 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
470 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
471 if (!(rq
->cmd_flags
& REQ_SOFTBARRIER
))
474 rq
->cmd_flags
&= ~REQ_SOFTBARRIER
;
475 list_del_init(&rq
->queuelist
);
476 blk_mq_insert_request(rq
, true, false, false);
479 while (!list_empty(&rq_list
)) {
480 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
481 list_del_init(&rq
->queuelist
);
482 blk_mq_insert_request(rq
, false, false, false);
486 * Use the start variant of queue running here, so that running
487 * the requeue work will kick stopped queues.
489 blk_mq_start_hw_queues(q
);
492 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
)
494 struct request_queue
*q
= rq
->q
;
498 * We abuse this flag that is otherwise used by the I/O scheduler to
499 * request head insertation from the workqueue.
501 BUG_ON(rq
->cmd_flags
& REQ_SOFTBARRIER
);
503 spin_lock_irqsave(&q
->requeue_lock
, flags
);
505 rq
->cmd_flags
|= REQ_SOFTBARRIER
;
506 list_add(&rq
->queuelist
, &q
->requeue_list
);
508 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
510 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
512 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
514 void blk_mq_cancel_requeue_work(struct request_queue
*q
)
516 cancel_work_sync(&q
->requeue_work
);
518 EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work
);
520 void blk_mq_kick_requeue_list(struct request_queue
*q
)
522 kblockd_schedule_work(&q
->requeue_work
);
524 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
526 void blk_mq_abort_requeue_list(struct request_queue
*q
)
531 spin_lock_irqsave(&q
->requeue_lock
, flags
);
532 list_splice_init(&q
->requeue_list
, &rq_list
);
533 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
535 while (!list_empty(&rq_list
)) {
538 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
539 list_del_init(&rq
->queuelist
);
541 blk_mq_end_request(rq
, rq
->errors
);
544 EXPORT_SYMBOL(blk_mq_abort_requeue_list
);
546 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
548 if (tag
< tags
->nr_tags
)
549 return tags
->rqs
[tag
];
553 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
555 struct blk_mq_timeout_data
{
557 unsigned int next_set
;
560 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
562 struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
563 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
566 * We know that complete is set at this point. If STARTED isn't set
567 * anymore, then the request isn't active and the "timeout" should
568 * just be ignored. This can happen due to the bitflag ordering.
569 * Timeout first checks if STARTED is set, and if it is, assumes
570 * the request is active. But if we race with completion, then
571 * we both flags will get cleared. So check here again, and ignore
572 * a timeout event with a request that isn't active.
574 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
578 ret
= ops
->timeout(req
, reserved
);
582 __blk_mq_complete_request(req
);
584 case BLK_EH_RESET_TIMER
:
586 blk_clear_rq_complete(req
);
588 case BLK_EH_NOT_HANDLED
:
591 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
596 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
597 struct request
*rq
, void *priv
, bool reserved
)
599 struct blk_mq_timeout_data
*data
= priv
;
601 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
603 * If a request wasn't started before the queue was
604 * marked dying, kill it here or it'll go unnoticed.
606 if (unlikely(blk_queue_dying(rq
->q
))) {
608 blk_mq_end_request(rq
, rq
->errors
);
613 if (time_after_eq(jiffies
, rq
->deadline
)) {
614 if (!blk_mark_rq_complete(rq
))
615 blk_mq_rq_timed_out(rq
, reserved
);
616 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
617 data
->next
= rq
->deadline
;
622 static void blk_mq_timeout_work(struct work_struct
*work
)
624 struct request_queue
*q
=
625 container_of(work
, struct request_queue
, timeout_work
);
626 struct blk_mq_timeout_data data
= {
632 if (blk_queue_enter(q
, true))
635 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
638 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
639 mod_timer(&q
->timeout
, data
.next
);
641 struct blk_mq_hw_ctx
*hctx
;
643 queue_for_each_hw_ctx(q
, hctx
, i
) {
644 /* the hctx may be unmapped, so check it here */
645 if (blk_mq_hw_queue_mapped(hctx
))
646 blk_mq_tag_idle(hctx
);
653 * Reverse check our software queue for entries that we could potentially
654 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
655 * too much time checking for merges.
657 static bool blk_mq_attempt_merge(struct request_queue
*q
,
658 struct blk_mq_ctx
*ctx
, struct bio
*bio
)
663 list_for_each_entry_reverse(rq
, &ctx
->rq_list
, queuelist
) {
669 if (!blk_rq_merge_ok(rq
, bio
))
672 el_ret
= blk_try_merge(rq
, bio
);
673 if (el_ret
== ELEVATOR_BACK_MERGE
) {
674 if (bio_attempt_back_merge(q
, rq
, bio
)) {
679 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
680 if (bio_attempt_front_merge(q
, rq
, bio
)) {
692 * Process software queues that have been marked busy, splicing them
693 * to the for-dispatch
695 static void flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
697 struct blk_mq_ctx
*ctx
;
700 for (i
= 0; i
< hctx
->ctx_map
.size
; i
++) {
701 struct blk_align_bitmap
*bm
= &hctx
->ctx_map
.map
[i
];
702 unsigned int off
, bit
;
708 off
= i
* hctx
->ctx_map
.bits_per_word
;
710 bit
= find_next_bit(&bm
->word
, bm
->depth
, bit
);
711 if (bit
>= bm
->depth
)
714 ctx
= hctx
->ctxs
[bit
+ off
];
715 clear_bit(bit
, &bm
->word
);
716 spin_lock(&ctx
->lock
);
717 list_splice_tail_init(&ctx
->rq_list
, list
);
718 spin_unlock(&ctx
->lock
);
726 * Run this hardware queue, pulling any software queues mapped to it in.
727 * Note that this function currently has various problems around ordering
728 * of IO. In particular, we'd like FIFO behaviour on handling existing
729 * items on the hctx->dispatch list. Ignore that for now.
731 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
733 struct request_queue
*q
= hctx
->queue
;
736 LIST_HEAD(driver_list
);
737 struct list_head
*dptr
;
740 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
));
742 if (unlikely(test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)))
748 * Touch any software queue that has pending entries.
750 flush_busy_ctxs(hctx
, &rq_list
);
753 * If we have previous entries on our dispatch list, grab them
754 * and stuff them at the front for more fair dispatch.
756 if (!list_empty_careful(&hctx
->dispatch
)) {
757 spin_lock(&hctx
->lock
);
758 if (!list_empty(&hctx
->dispatch
))
759 list_splice_init(&hctx
->dispatch
, &rq_list
);
760 spin_unlock(&hctx
->lock
);
764 * Start off with dptr being NULL, so we start the first request
765 * immediately, even if we have more pending.
770 * Now process all the entries, sending them to the driver.
773 while (!list_empty(&rq_list
)) {
774 struct blk_mq_queue_data bd
;
777 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
778 list_del_init(&rq
->queuelist
);
782 bd
.last
= list_empty(&rq_list
);
784 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
786 case BLK_MQ_RQ_QUEUE_OK
:
789 case BLK_MQ_RQ_QUEUE_BUSY
:
790 list_add(&rq
->queuelist
, &rq_list
);
791 __blk_mq_requeue_request(rq
);
794 pr_err("blk-mq: bad return on queue: %d\n", ret
);
795 case BLK_MQ_RQ_QUEUE_ERROR
:
797 blk_mq_end_request(rq
, rq
->errors
);
801 if (ret
== BLK_MQ_RQ_QUEUE_BUSY
)
805 * We've done the first request. If we have more than 1
806 * left in the list, set dptr to defer issue.
808 if (!dptr
&& rq_list
.next
!= rq_list
.prev
)
813 hctx
->dispatched
[0]++;
814 else if (queued
< (1 << (BLK_MQ_MAX_DISPATCH_ORDER
- 1)))
815 hctx
->dispatched
[ilog2(queued
) + 1]++;
818 * Any items that need requeuing? Stuff them into hctx->dispatch,
819 * that is where we will continue on next queue run.
821 if (!list_empty(&rq_list
)) {
822 spin_lock(&hctx
->lock
);
823 list_splice(&rq_list
, &hctx
->dispatch
);
824 spin_unlock(&hctx
->lock
);
826 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
827 * it's possible the queue is stopped and restarted again
828 * before this. Queue restart will dispatch requests. And since
829 * requests in rq_list aren't added into hctx->dispatch yet,
830 * the requests in rq_list might get lost.
832 * blk_mq_run_hw_queue() already checks the STOPPED bit
834 blk_mq_run_hw_queue(hctx
, true);
839 * It'd be great if the workqueue API had a way to pass
840 * in a mask and had some smarts for more clever placement.
841 * For now we just round-robin here, switching for every
842 * BLK_MQ_CPU_WORK_BATCH queued items.
844 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
846 if (hctx
->queue
->nr_hw_queues
== 1)
847 return WORK_CPU_UNBOUND
;
849 if (--hctx
->next_cpu_batch
<= 0) {
850 int cpu
= hctx
->next_cpu
, next_cpu
;
852 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
853 if (next_cpu
>= nr_cpu_ids
)
854 next_cpu
= cpumask_first(hctx
->cpumask
);
856 hctx
->next_cpu
= next_cpu
;
857 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
862 return hctx
->next_cpu
;
865 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
867 if (unlikely(test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
) ||
868 !blk_mq_hw_queue_mapped(hctx
)))
873 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
874 __blk_mq_run_hw_queue(hctx
);
882 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
886 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
888 struct blk_mq_hw_ctx
*hctx
;
891 queue_for_each_hw_ctx(q
, hctx
, i
) {
892 if ((!blk_mq_hctx_has_pending(hctx
) &&
893 list_empty_careful(&hctx
->dispatch
)) ||
894 test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
897 blk_mq_run_hw_queue(hctx
, async
);
900 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
902 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
904 cancel_delayed_work(&hctx
->run_work
);
905 cancel_delayed_work(&hctx
->delay_work
);
906 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
908 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
910 void blk_mq_stop_hw_queues(struct request_queue
*q
)
912 struct blk_mq_hw_ctx
*hctx
;
915 queue_for_each_hw_ctx(q
, hctx
, i
)
916 blk_mq_stop_hw_queue(hctx
);
918 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
920 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
922 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
924 blk_mq_run_hw_queue(hctx
, false);
926 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
928 void blk_mq_start_hw_queues(struct request_queue
*q
)
930 struct blk_mq_hw_ctx
*hctx
;
933 queue_for_each_hw_ctx(q
, hctx
, i
)
934 blk_mq_start_hw_queue(hctx
);
936 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
938 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
940 struct blk_mq_hw_ctx
*hctx
;
943 queue_for_each_hw_ctx(q
, hctx
, i
) {
944 if (!test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
947 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
948 blk_mq_run_hw_queue(hctx
, async
);
951 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
953 static void blk_mq_run_work_fn(struct work_struct
*work
)
955 struct blk_mq_hw_ctx
*hctx
;
957 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
959 __blk_mq_run_hw_queue(hctx
);
962 static void blk_mq_delay_work_fn(struct work_struct
*work
)
964 struct blk_mq_hw_ctx
*hctx
;
966 hctx
= container_of(work
, struct blk_mq_hw_ctx
, delay_work
.work
);
968 if (test_and_clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
969 __blk_mq_run_hw_queue(hctx
);
972 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
974 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
977 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
978 &hctx
->delay_work
, msecs_to_jiffies(msecs
));
980 EXPORT_SYMBOL(blk_mq_delay_queue
);
982 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
983 struct blk_mq_ctx
*ctx
,
987 trace_block_rq_insert(hctx
->queue
, rq
);
990 list_add(&rq
->queuelist
, &ctx
->rq_list
);
992 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
995 static void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
,
996 struct request
*rq
, bool at_head
)
998 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1000 __blk_mq_insert_req_list(hctx
, ctx
, rq
, at_head
);
1001 blk_mq_hctx_mark_pending(hctx
, ctx
);
1004 void blk_mq_insert_request(struct request
*rq
, bool at_head
, bool run_queue
,
1007 struct request_queue
*q
= rq
->q
;
1008 struct blk_mq_hw_ctx
*hctx
;
1009 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
, *current_ctx
;
1011 current_ctx
= blk_mq_get_ctx(q
);
1012 if (!cpu_online(ctx
->cpu
))
1013 rq
->mq_ctx
= ctx
= current_ctx
;
1015 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1017 spin_lock(&ctx
->lock
);
1018 __blk_mq_insert_request(hctx
, rq
, at_head
);
1019 spin_unlock(&ctx
->lock
);
1022 blk_mq_run_hw_queue(hctx
, async
);
1024 blk_mq_put_ctx(current_ctx
);
1027 static void blk_mq_insert_requests(struct request_queue
*q
,
1028 struct blk_mq_ctx
*ctx
,
1029 struct list_head
*list
,
1034 struct blk_mq_hw_ctx
*hctx
;
1035 struct blk_mq_ctx
*current_ctx
;
1037 trace_block_unplug(q
, depth
, !from_schedule
);
1039 current_ctx
= blk_mq_get_ctx(q
);
1041 if (!cpu_online(ctx
->cpu
))
1043 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1046 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1049 spin_lock(&ctx
->lock
);
1050 while (!list_empty(list
)) {
1053 rq
= list_first_entry(list
, struct request
, queuelist
);
1054 list_del_init(&rq
->queuelist
);
1056 __blk_mq_insert_req_list(hctx
, ctx
, rq
, false);
1058 blk_mq_hctx_mark_pending(hctx
, ctx
);
1059 spin_unlock(&ctx
->lock
);
1061 blk_mq_run_hw_queue(hctx
, from_schedule
);
1062 blk_mq_put_ctx(current_ctx
);
1065 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1067 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1068 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1070 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1071 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1072 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1075 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1077 struct blk_mq_ctx
*this_ctx
;
1078 struct request_queue
*this_q
;
1081 LIST_HEAD(ctx_list
);
1084 list_splice_init(&plug
->mq_list
, &list
);
1086 list_sort(NULL
, &list
, plug_ctx_cmp
);
1092 while (!list_empty(&list
)) {
1093 rq
= list_entry_rq(list
.next
);
1094 list_del_init(&rq
->queuelist
);
1096 if (rq
->mq_ctx
!= this_ctx
) {
1098 blk_mq_insert_requests(this_q
, this_ctx
,
1103 this_ctx
= rq
->mq_ctx
;
1109 list_add_tail(&rq
->queuelist
, &ctx_list
);
1113 * If 'this_ctx' is set, we know we have entries to complete
1114 * on 'ctx_list'. Do those.
1117 blk_mq_insert_requests(this_q
, this_ctx
, &ctx_list
, depth
,
1122 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1124 init_request_from_bio(rq
, bio
);
1126 blk_account_io_start(rq
, 1);
1129 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1131 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1132 !blk_queue_nomerges(hctx
->queue
);
1135 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx
*hctx
,
1136 struct blk_mq_ctx
*ctx
,
1137 struct request
*rq
, struct bio
*bio
)
1139 if (!hctx_allow_merges(hctx
) || !bio_mergeable(bio
)) {
1140 blk_mq_bio_to_request(rq
, bio
);
1141 spin_lock(&ctx
->lock
);
1143 __blk_mq_insert_request(hctx
, rq
, false);
1144 spin_unlock(&ctx
->lock
);
1147 struct request_queue
*q
= hctx
->queue
;
1149 spin_lock(&ctx
->lock
);
1150 if (!blk_mq_attempt_merge(q
, ctx
, bio
)) {
1151 blk_mq_bio_to_request(rq
, bio
);
1155 spin_unlock(&ctx
->lock
);
1156 __blk_mq_free_request(hctx
, ctx
, rq
);
1161 struct blk_map_ctx
{
1162 struct blk_mq_hw_ctx
*hctx
;
1163 struct blk_mq_ctx
*ctx
;
1166 static struct request
*blk_mq_map_request(struct request_queue
*q
,
1168 struct blk_map_ctx
*data
)
1170 struct blk_mq_hw_ctx
*hctx
;
1171 struct blk_mq_ctx
*ctx
;
1173 int op
= bio_data_dir(bio
);
1175 struct blk_mq_alloc_data alloc_data
;
1177 blk_queue_enter_live(q
);
1178 ctx
= blk_mq_get_ctx(q
);
1179 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1181 if (rw_is_sync(bio_op(bio
), bio
->bi_rw
))
1182 op_flags
|= REQ_SYNC
;
1184 trace_block_getrq(q
, bio
, op
);
1185 blk_mq_set_alloc_data(&alloc_data
, q
, BLK_MQ_REQ_NOWAIT
, ctx
, hctx
);
1186 rq
= __blk_mq_alloc_request(&alloc_data
, op
, op_flags
);
1187 if (unlikely(!rq
)) {
1188 __blk_mq_run_hw_queue(hctx
);
1189 blk_mq_put_ctx(ctx
);
1190 trace_block_sleeprq(q
, bio
, op
);
1192 ctx
= blk_mq_get_ctx(q
);
1193 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1194 blk_mq_set_alloc_data(&alloc_data
, q
, 0, ctx
, hctx
);
1195 rq
= __blk_mq_alloc_request(&alloc_data
, op
, op_flags
);
1196 ctx
= alloc_data
.ctx
;
1197 hctx
= alloc_data
.hctx
;
1206 static int blk_mq_direct_issue_request(struct request
*rq
, blk_qc_t
*cookie
)
1209 struct request_queue
*q
= rq
->q
;
1210 struct blk_mq_hw_ctx
*hctx
= q
->mq_ops
->map_queue(q
,
1212 struct blk_mq_queue_data bd
= {
1217 blk_qc_t new_cookie
= blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
);
1220 * For OK queue, we are done. For error, kill it. Any other
1221 * error (busy), just add it to our list as we previously
1224 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1225 if (ret
== BLK_MQ_RQ_QUEUE_OK
) {
1226 *cookie
= new_cookie
;
1230 __blk_mq_requeue_request(rq
);
1232 if (ret
== BLK_MQ_RQ_QUEUE_ERROR
) {
1233 *cookie
= BLK_QC_T_NONE
;
1235 blk_mq_end_request(rq
, rq
->errors
);
1243 * Multiple hardware queue variant. This will not use per-process plugs,
1244 * but will attempt to bypass the hctx queueing if we can go straight to
1245 * hardware for SYNC IO.
1247 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1249 const int is_sync
= rw_is_sync(bio_op(bio
), bio
->bi_rw
);
1250 const int is_flush_fua
= bio
->bi_rw
& (REQ_PREFLUSH
| REQ_FUA
);
1251 struct blk_map_ctx data
;
1253 unsigned int request_count
= 0;
1254 struct blk_plug
*plug
;
1255 struct request
*same_queue_rq
= NULL
;
1258 blk_queue_bounce(q
, &bio
);
1260 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1262 return BLK_QC_T_NONE
;
1265 blk_queue_split(q
, &bio
, q
->bio_split
);
1267 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1268 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1269 return BLK_QC_T_NONE
;
1271 rq
= blk_mq_map_request(q
, bio
, &data
);
1273 return BLK_QC_T_NONE
;
1275 cookie
= blk_tag_to_qc_t(rq
->tag
, data
.hctx
->queue_num
);
1277 if (unlikely(is_flush_fua
)) {
1278 blk_mq_bio_to_request(rq
, bio
);
1279 blk_insert_flush(rq
);
1283 plug
= current
->plug
;
1285 * If the driver supports defer issued based on 'last', then
1286 * queue it up like normal since we can potentially save some
1289 if (((plug
&& !blk_queue_nomerges(q
)) || is_sync
) &&
1290 !(data
.hctx
->flags
& BLK_MQ_F_DEFER_ISSUE
)) {
1291 struct request
*old_rq
= NULL
;
1293 blk_mq_bio_to_request(rq
, bio
);
1296 * We do limited pluging. If the bio can be merged, do that.
1297 * Otherwise the existing request in the plug list will be
1298 * issued. So the plug list will have one request at most
1302 * The plug list might get flushed before this. If that
1303 * happens, same_queue_rq is invalid and plug list is
1306 if (same_queue_rq
&& !list_empty(&plug
->mq_list
)) {
1307 old_rq
= same_queue_rq
;
1308 list_del_init(&old_rq
->queuelist
);
1310 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1311 } else /* is_sync */
1313 blk_mq_put_ctx(data
.ctx
);
1316 if (!blk_mq_direct_issue_request(old_rq
, &cookie
))
1318 blk_mq_insert_request(old_rq
, false, true, true);
1322 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1324 * For a SYNC request, send it to the hardware immediately. For
1325 * an ASYNC request, just ensure that we run it later on. The
1326 * latter allows for merging opportunities and more efficient
1330 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1332 blk_mq_put_ctx(data
.ctx
);
1338 * Single hardware queue variant. This will attempt to use any per-process
1339 * plug for merging and IO deferral.
1341 static blk_qc_t
blk_sq_make_request(struct request_queue
*q
, struct bio
*bio
)
1343 const int is_sync
= rw_is_sync(bio_op(bio
), bio
->bi_rw
);
1344 const int is_flush_fua
= bio
->bi_rw
& (REQ_PREFLUSH
| REQ_FUA
);
1345 struct blk_plug
*plug
;
1346 unsigned int request_count
= 0;
1347 struct blk_map_ctx data
;
1351 blk_queue_bounce(q
, &bio
);
1353 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1355 return BLK_QC_T_NONE
;
1358 blk_queue_split(q
, &bio
, q
->bio_split
);
1360 if (!is_flush_fua
&& !blk_queue_nomerges(q
)) {
1361 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1362 return BLK_QC_T_NONE
;
1364 request_count
= blk_plug_queued_count(q
);
1366 rq
= blk_mq_map_request(q
, bio
, &data
);
1368 return BLK_QC_T_NONE
;
1370 cookie
= blk_tag_to_qc_t(rq
->tag
, data
.hctx
->queue_num
);
1372 if (unlikely(is_flush_fua
)) {
1373 blk_mq_bio_to_request(rq
, bio
);
1374 blk_insert_flush(rq
);
1379 * A task plug currently exists. Since this is completely lockless,
1380 * utilize that to temporarily store requests until the task is
1381 * either done or scheduled away.
1383 plug
= current
->plug
;
1385 blk_mq_bio_to_request(rq
, bio
);
1387 trace_block_plug(q
);
1389 blk_mq_put_ctx(data
.ctx
);
1391 if (request_count
>= BLK_MAX_REQUEST_COUNT
) {
1392 blk_flush_plug_list(plug
, false);
1393 trace_block_plug(q
);
1396 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1400 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1402 * For a SYNC request, send it to the hardware immediately. For
1403 * an ASYNC request, just ensure that we run it later on. The
1404 * latter allows for merging opportunities and more efficient
1408 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1411 blk_mq_put_ctx(data
.ctx
);
1416 * Default mapping to a software queue, since we use one per CPU.
1418 struct blk_mq_hw_ctx
*blk_mq_map_queue(struct request_queue
*q
, const int cpu
)
1420 return q
->queue_hw_ctx
[q
->mq_map
[cpu
]];
1422 EXPORT_SYMBOL(blk_mq_map_queue
);
1424 static void blk_mq_free_rq_map(struct blk_mq_tag_set
*set
,
1425 struct blk_mq_tags
*tags
, unsigned int hctx_idx
)
1429 if (tags
->rqs
&& set
->ops
->exit_request
) {
1432 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1435 set
->ops
->exit_request(set
->driver_data
, tags
->rqs
[i
],
1437 tags
->rqs
[i
] = NULL
;
1441 while (!list_empty(&tags
->page_list
)) {
1442 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1443 list_del_init(&page
->lru
);
1445 * Remove kmemleak object previously allocated in
1446 * blk_mq_init_rq_map().
1448 kmemleak_free(page_address(page
));
1449 __free_pages(page
, page
->private);
1454 blk_mq_free_tags(tags
);
1457 static size_t order_to_size(unsigned int order
)
1459 return (size_t)PAGE_SIZE
<< order
;
1462 static struct blk_mq_tags
*blk_mq_init_rq_map(struct blk_mq_tag_set
*set
,
1463 unsigned int hctx_idx
)
1465 struct blk_mq_tags
*tags
;
1466 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1467 size_t rq_size
, left
;
1469 tags
= blk_mq_init_tags(set
->queue_depth
, set
->reserved_tags
,
1471 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1475 INIT_LIST_HEAD(&tags
->page_list
);
1477 tags
->rqs
= kzalloc_node(set
->queue_depth
* sizeof(struct request
*),
1478 GFP_KERNEL
| __GFP_NOWARN
| __GFP_NORETRY
,
1481 blk_mq_free_tags(tags
);
1486 * rq_size is the size of the request plus driver payload, rounded
1487 * to the cacheline size
1489 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1491 left
= rq_size
* set
->queue_depth
;
1493 for (i
= 0; i
< set
->queue_depth
; ) {
1494 int this_order
= max_order
;
1499 while (this_order
&& left
< order_to_size(this_order
- 1))
1503 page
= alloc_pages_node(set
->numa_node
,
1504 GFP_KERNEL
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1510 if (order_to_size(this_order
) < rq_size
)
1517 page
->private = this_order
;
1518 list_add_tail(&page
->lru
, &tags
->page_list
);
1520 p
= page_address(page
);
1522 * Allow kmemleak to scan these pages as they contain pointers
1523 * to additional allocations like via ops->init_request().
1525 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_KERNEL
);
1526 entries_per_page
= order_to_size(this_order
) / rq_size
;
1527 to_do
= min(entries_per_page
, set
->queue_depth
- i
);
1528 left
-= to_do
* rq_size
;
1529 for (j
= 0; j
< to_do
; j
++) {
1531 if (set
->ops
->init_request
) {
1532 if (set
->ops
->init_request(set
->driver_data
,
1533 tags
->rqs
[i
], hctx_idx
, i
,
1535 tags
->rqs
[i
] = NULL
;
1547 blk_mq_free_rq_map(set
, tags
, hctx_idx
);
1551 static void blk_mq_free_bitmap(struct blk_mq_ctxmap
*bitmap
)
1556 static int blk_mq_alloc_bitmap(struct blk_mq_ctxmap
*bitmap
, int node
)
1558 unsigned int bpw
= 8, total
, num_maps
, i
;
1560 bitmap
->bits_per_word
= bpw
;
1562 num_maps
= ALIGN(nr_cpu_ids
, bpw
) / bpw
;
1563 bitmap
->map
= kzalloc_node(num_maps
* sizeof(struct blk_align_bitmap
),
1569 for (i
= 0; i
< num_maps
; i
++) {
1570 bitmap
->map
[i
].depth
= min(total
, bitmap
->bits_per_word
);
1571 total
-= bitmap
->map
[i
].depth
;
1577 static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx
*hctx
, int cpu
)
1579 struct request_queue
*q
= hctx
->queue
;
1580 struct blk_mq_ctx
*ctx
;
1584 * Move ctx entries to new CPU, if this one is going away.
1586 ctx
= __blk_mq_get_ctx(q
, cpu
);
1588 spin_lock(&ctx
->lock
);
1589 if (!list_empty(&ctx
->rq_list
)) {
1590 list_splice_init(&ctx
->rq_list
, &tmp
);
1591 blk_mq_hctx_clear_pending(hctx
, ctx
);
1593 spin_unlock(&ctx
->lock
);
1595 if (list_empty(&tmp
))
1598 ctx
= blk_mq_get_ctx(q
);
1599 spin_lock(&ctx
->lock
);
1601 while (!list_empty(&tmp
)) {
1604 rq
= list_first_entry(&tmp
, struct request
, queuelist
);
1606 list_move_tail(&rq
->queuelist
, &ctx
->rq_list
);
1609 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1610 blk_mq_hctx_mark_pending(hctx
, ctx
);
1612 spin_unlock(&ctx
->lock
);
1614 blk_mq_run_hw_queue(hctx
, true);
1615 blk_mq_put_ctx(ctx
);
1619 static int blk_mq_hctx_notify(void *data
, unsigned long action
,
1622 struct blk_mq_hw_ctx
*hctx
= data
;
1624 if (action
== CPU_DEAD
|| action
== CPU_DEAD_FROZEN
)
1625 return blk_mq_hctx_cpu_offline(hctx
, cpu
);
1628 * In case of CPU online, tags may be reallocated
1629 * in blk_mq_map_swqueue() after mapping is updated.
1635 /* hctx->ctxs will be freed in queue's release handler */
1636 static void blk_mq_exit_hctx(struct request_queue
*q
,
1637 struct blk_mq_tag_set
*set
,
1638 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1640 unsigned flush_start_tag
= set
->queue_depth
;
1642 blk_mq_tag_idle(hctx
);
1644 if (set
->ops
->exit_request
)
1645 set
->ops
->exit_request(set
->driver_data
,
1646 hctx
->fq
->flush_rq
, hctx_idx
,
1647 flush_start_tag
+ hctx_idx
);
1649 if (set
->ops
->exit_hctx
)
1650 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1652 blk_mq_unregister_cpu_notifier(&hctx
->cpu_notifier
);
1653 blk_free_flush_queue(hctx
->fq
);
1654 blk_mq_free_bitmap(&hctx
->ctx_map
);
1657 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1658 struct blk_mq_tag_set
*set
, int nr_queue
)
1660 struct blk_mq_hw_ctx
*hctx
;
1663 queue_for_each_hw_ctx(q
, hctx
, i
) {
1666 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1670 static void blk_mq_free_hw_queues(struct request_queue
*q
,
1671 struct blk_mq_tag_set
*set
)
1673 struct blk_mq_hw_ctx
*hctx
;
1676 queue_for_each_hw_ctx(q
, hctx
, i
)
1677 free_cpumask_var(hctx
->cpumask
);
1680 static int blk_mq_init_hctx(struct request_queue
*q
,
1681 struct blk_mq_tag_set
*set
,
1682 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1685 unsigned flush_start_tag
= set
->queue_depth
;
1687 node
= hctx
->numa_node
;
1688 if (node
== NUMA_NO_NODE
)
1689 node
= hctx
->numa_node
= set
->numa_node
;
1691 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1692 INIT_DELAYED_WORK(&hctx
->delay_work
, blk_mq_delay_work_fn
);
1693 spin_lock_init(&hctx
->lock
);
1694 INIT_LIST_HEAD(&hctx
->dispatch
);
1696 hctx
->queue_num
= hctx_idx
;
1697 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1699 blk_mq_init_cpu_notifier(&hctx
->cpu_notifier
,
1700 blk_mq_hctx_notify
, hctx
);
1701 blk_mq_register_cpu_notifier(&hctx
->cpu_notifier
);
1703 hctx
->tags
= set
->tags
[hctx_idx
];
1706 * Allocate space for all possible cpus to avoid allocation at
1709 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1712 goto unregister_cpu_notifier
;
1714 if (blk_mq_alloc_bitmap(&hctx
->ctx_map
, node
))
1719 if (set
->ops
->init_hctx
&&
1720 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1723 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
1727 if (set
->ops
->init_request
&&
1728 set
->ops
->init_request(set
->driver_data
,
1729 hctx
->fq
->flush_rq
, hctx_idx
,
1730 flush_start_tag
+ hctx_idx
, node
))
1738 if (set
->ops
->exit_hctx
)
1739 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1741 blk_mq_free_bitmap(&hctx
->ctx_map
);
1744 unregister_cpu_notifier
:
1745 blk_mq_unregister_cpu_notifier(&hctx
->cpu_notifier
);
1750 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
1751 unsigned int nr_hw_queues
)
1755 for_each_possible_cpu(i
) {
1756 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1757 struct blk_mq_hw_ctx
*hctx
;
1759 memset(__ctx
, 0, sizeof(*__ctx
));
1761 spin_lock_init(&__ctx
->lock
);
1762 INIT_LIST_HEAD(&__ctx
->rq_list
);
1765 /* If the cpu isn't online, the cpu is mapped to first hctx */
1769 hctx
= q
->mq_ops
->map_queue(q
, i
);
1772 * Set local node, IFF we have more than one hw queue. If
1773 * not, we remain on the home node of the device
1775 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
1776 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
1780 static void blk_mq_map_swqueue(struct request_queue
*q
,
1781 const struct cpumask
*online_mask
)
1784 struct blk_mq_hw_ctx
*hctx
;
1785 struct blk_mq_ctx
*ctx
;
1786 struct blk_mq_tag_set
*set
= q
->tag_set
;
1789 * Avoid others reading imcomplete hctx->cpumask through sysfs
1791 mutex_lock(&q
->sysfs_lock
);
1793 queue_for_each_hw_ctx(q
, hctx
, i
) {
1794 cpumask_clear(hctx
->cpumask
);
1799 * Map software to hardware queues
1801 for_each_possible_cpu(i
) {
1802 /* If the cpu isn't online, the cpu is mapped to first hctx */
1803 if (!cpumask_test_cpu(i
, online_mask
))
1806 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1807 hctx
= q
->mq_ops
->map_queue(q
, i
);
1809 cpumask_set_cpu(i
, hctx
->cpumask
);
1810 ctx
->index_hw
= hctx
->nr_ctx
;
1811 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
1814 mutex_unlock(&q
->sysfs_lock
);
1816 queue_for_each_hw_ctx(q
, hctx
, i
) {
1817 struct blk_mq_ctxmap
*map
= &hctx
->ctx_map
;
1820 * If no software queues are mapped to this hardware queue,
1821 * disable it and free the request entries.
1823 if (!hctx
->nr_ctx
) {
1825 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
1826 set
->tags
[i
] = NULL
;
1832 /* unmapped hw queue can be remapped after CPU topo changed */
1834 set
->tags
[i
] = blk_mq_init_rq_map(set
, i
);
1835 hctx
->tags
= set
->tags
[i
];
1836 WARN_ON(!hctx
->tags
);
1838 cpumask_copy(hctx
->tags
->cpumask
, hctx
->cpumask
);
1840 * Set the map size to the number of mapped software queues.
1841 * This is more accurate and more efficient than looping
1842 * over all possibly mapped software queues.
1844 map
->size
= DIV_ROUND_UP(hctx
->nr_ctx
, map
->bits_per_word
);
1847 * Initialize batch roundrobin counts
1849 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
1850 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1854 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
1856 struct blk_mq_hw_ctx
*hctx
;
1859 queue_for_each_hw_ctx(q
, hctx
, i
) {
1861 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
1863 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
1867 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
1869 struct request_queue
*q
;
1871 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
1872 blk_mq_freeze_queue(q
);
1873 queue_set_hctx_shared(q
, shared
);
1874 blk_mq_unfreeze_queue(q
);
1878 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
1880 struct blk_mq_tag_set
*set
= q
->tag_set
;
1882 mutex_lock(&set
->tag_list_lock
);
1883 list_del_init(&q
->tag_set_list
);
1884 if (list_is_singular(&set
->tag_list
)) {
1885 /* just transitioned to unshared */
1886 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
1887 /* update existing queue */
1888 blk_mq_update_tag_set_depth(set
, false);
1890 mutex_unlock(&set
->tag_list_lock
);
1893 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
1894 struct request_queue
*q
)
1898 mutex_lock(&set
->tag_list_lock
);
1900 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
1901 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1902 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
1903 /* update existing queue */
1904 blk_mq_update_tag_set_depth(set
, true);
1906 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
1907 queue_set_hctx_shared(q
, true);
1908 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
1910 mutex_unlock(&set
->tag_list_lock
);
1914 * It is the actual release handler for mq, but we do it from
1915 * request queue's release handler for avoiding use-after-free
1916 * and headache because q->mq_kobj shouldn't have been introduced,
1917 * but we can't group ctx/kctx kobj without it.
1919 void blk_mq_release(struct request_queue
*q
)
1921 struct blk_mq_hw_ctx
*hctx
;
1924 /* hctx kobj stays in hctx */
1925 queue_for_each_hw_ctx(q
, hctx
, i
) {
1935 kfree(q
->queue_hw_ctx
);
1937 /* ctx kobj stays in queue_ctx */
1938 free_percpu(q
->queue_ctx
);
1941 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
1943 struct request_queue
*uninit_q
, *q
;
1945 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
1947 return ERR_PTR(-ENOMEM
);
1949 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
1951 blk_cleanup_queue(uninit_q
);
1955 EXPORT_SYMBOL(blk_mq_init_queue
);
1957 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
1958 struct request_queue
*q
)
1961 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
1963 blk_mq_sysfs_unregister(q
);
1964 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
1970 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
1971 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
1976 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
1983 atomic_set(&hctxs
[i
]->nr_active
, 0);
1984 hctxs
[i
]->numa_node
= node
;
1985 hctxs
[i
]->queue_num
= i
;
1987 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
1988 free_cpumask_var(hctxs
[i
]->cpumask
);
1993 blk_mq_hctx_kobj_init(hctxs
[i
]);
1995 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
1996 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2000 blk_mq_free_rq_map(set
, hctx
->tags
, j
);
2001 set
->tags
[j
] = NULL
;
2003 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2004 free_cpumask_var(hctx
->cpumask
);
2005 kobject_put(&hctx
->kobj
);
2012 q
->nr_hw_queues
= i
;
2013 blk_mq_sysfs_register(q
);
2016 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2017 struct request_queue
*q
)
2019 /* mark the queue as mq asap */
2020 q
->mq_ops
= set
->ops
;
2022 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2026 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2027 GFP_KERNEL
, set
->numa_node
);
2028 if (!q
->queue_hw_ctx
)
2031 q
->mq_map
= blk_mq_make_queue_map(set
);
2035 blk_mq_realloc_hw_ctxs(set
, q
);
2036 if (!q
->nr_hw_queues
)
2039 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2040 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2042 q
->nr_queues
= nr_cpu_ids
;
2044 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2046 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2047 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2049 q
->sg_reserved_size
= INT_MAX
;
2051 INIT_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2052 INIT_LIST_HEAD(&q
->requeue_list
);
2053 spin_lock_init(&q
->requeue_lock
);
2055 if (q
->nr_hw_queues
> 1)
2056 blk_queue_make_request(q
, blk_mq_make_request
);
2058 blk_queue_make_request(q
, blk_sq_make_request
);
2061 * Do this after blk_queue_make_request() overrides it...
2063 q
->nr_requests
= set
->queue_depth
;
2065 if (set
->ops
->complete
)
2066 blk_queue_softirq_done(q
, set
->ops
->complete
);
2068 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2071 mutex_lock(&all_q_mutex
);
2073 list_add_tail(&q
->all_q_node
, &all_q_list
);
2074 blk_mq_add_queue_tag_set(set
, q
);
2075 blk_mq_map_swqueue(q
, cpu_online_mask
);
2077 mutex_unlock(&all_q_mutex
);
2085 kfree(q
->queue_hw_ctx
);
2087 free_percpu(q
->queue_ctx
);
2090 return ERR_PTR(-ENOMEM
);
2092 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2094 void blk_mq_free_queue(struct request_queue
*q
)
2096 struct blk_mq_tag_set
*set
= q
->tag_set
;
2098 mutex_lock(&all_q_mutex
);
2099 list_del_init(&q
->all_q_node
);
2100 mutex_unlock(&all_q_mutex
);
2102 blk_mq_del_queue_tag_set(q
);
2104 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2105 blk_mq_free_hw_queues(q
, set
);
2108 /* Basically redo blk_mq_init_queue with queue frozen */
2109 static void blk_mq_queue_reinit(struct request_queue
*q
,
2110 const struct cpumask
*online_mask
)
2112 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2114 blk_mq_sysfs_unregister(q
);
2116 blk_mq_update_queue_map(q
->mq_map
, q
->nr_hw_queues
, online_mask
);
2119 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2120 * we should change hctx numa_node according to new topology (this
2121 * involves free and re-allocate memory, worthy doing?)
2124 blk_mq_map_swqueue(q
, online_mask
);
2126 blk_mq_sysfs_register(q
);
2129 static int blk_mq_queue_reinit_notify(struct notifier_block
*nb
,
2130 unsigned long action
, void *hcpu
)
2132 struct request_queue
*q
;
2133 int cpu
= (unsigned long)hcpu
;
2135 * New online cpumask which is going to be set in this hotplug event.
2136 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2137 * one-by-one and dynamically allocating this could result in a failure.
2139 static struct cpumask online_new
;
2142 * Before hotadded cpu starts handling requests, new mappings must
2143 * be established. Otherwise, these requests in hw queue might
2144 * never be dispatched.
2146 * For example, there is a single hw queue (hctx) and two CPU queues
2147 * (ctx0 for CPU0, and ctx1 for CPU1).
2149 * Now CPU1 is just onlined and a request is inserted into
2150 * ctx1->rq_list and set bit0 in pending bitmap as ctx1->index_hw is
2153 * And then while running hw queue, flush_busy_ctxs() finds bit0 is
2154 * set in pending bitmap and tries to retrieve requests in
2155 * hctx->ctxs[0]->rq_list. But htx->ctxs[0] is a pointer to ctx0,
2156 * so the request in ctx1->rq_list is ignored.
2158 switch (action
& ~CPU_TASKS_FROZEN
) {
2160 case CPU_UP_CANCELED
:
2161 cpumask_copy(&online_new
, cpu_online_mask
);
2163 case CPU_UP_PREPARE
:
2164 cpumask_copy(&online_new
, cpu_online_mask
);
2165 cpumask_set_cpu(cpu
, &online_new
);
2171 mutex_lock(&all_q_mutex
);
2174 * We need to freeze and reinit all existing queues. Freezing
2175 * involves synchronous wait for an RCU grace period and doing it
2176 * one by one may take a long time. Start freezing all queues in
2177 * one swoop and then wait for the completions so that freezing can
2178 * take place in parallel.
2180 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2181 blk_mq_freeze_queue_start(q
);
2182 list_for_each_entry(q
, &all_q_list
, all_q_node
) {
2183 blk_mq_freeze_queue_wait(q
);
2186 * timeout handler can't touch hw queue during the
2189 del_timer_sync(&q
->timeout
);
2192 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2193 blk_mq_queue_reinit(q
, &online_new
);
2195 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2196 blk_mq_unfreeze_queue(q
);
2198 mutex_unlock(&all_q_mutex
);
2202 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2206 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2207 set
->tags
[i
] = blk_mq_init_rq_map(set
, i
);
2216 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
2222 * Allocate the request maps associated with this tag_set. Note that this
2223 * may reduce the depth asked for, if memory is tight. set->queue_depth
2224 * will be updated to reflect the allocated depth.
2226 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2231 depth
= set
->queue_depth
;
2233 err
= __blk_mq_alloc_rq_maps(set
);
2237 set
->queue_depth
>>= 1;
2238 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2242 } while (set
->queue_depth
);
2244 if (!set
->queue_depth
|| err
) {
2245 pr_err("blk-mq: failed to allocate request map\n");
2249 if (depth
!= set
->queue_depth
)
2250 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2251 depth
, set
->queue_depth
);
2256 struct cpumask
*blk_mq_tags_cpumask(struct blk_mq_tags
*tags
)
2258 return tags
->cpumask
;
2260 EXPORT_SYMBOL_GPL(blk_mq_tags_cpumask
);
2263 * Alloc a tag set to be associated with one or more request queues.
2264 * May fail with EINVAL for various error conditions. May adjust the
2265 * requested depth down, if if it too large. In that case, the set
2266 * value will be stored in set->queue_depth.
2268 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2270 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2272 if (!set
->nr_hw_queues
)
2274 if (!set
->queue_depth
)
2276 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2279 if (!set
->ops
->queue_rq
|| !set
->ops
->map_queue
)
2282 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2283 pr_info("blk-mq: reduced tag depth to %u\n",
2285 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2289 * If a crashdump is active, then we are potentially in a very
2290 * memory constrained environment. Limit us to 1 queue and
2291 * 64 tags to prevent using too much memory.
2293 if (is_kdump_kernel()) {
2294 set
->nr_hw_queues
= 1;
2295 set
->queue_depth
= min(64U, set
->queue_depth
);
2298 * There is no use for more h/w queues than cpus.
2300 if (set
->nr_hw_queues
> nr_cpu_ids
)
2301 set
->nr_hw_queues
= nr_cpu_ids
;
2303 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2304 GFP_KERNEL
, set
->numa_node
);
2308 if (blk_mq_alloc_rq_maps(set
))
2311 mutex_init(&set
->tag_list_lock
);
2312 INIT_LIST_HEAD(&set
->tag_list
);
2320 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2322 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2326 for (i
= 0; i
< nr_cpu_ids
; i
++) {
2328 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
2334 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2336 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2338 struct blk_mq_tag_set
*set
= q
->tag_set
;
2339 struct blk_mq_hw_ctx
*hctx
;
2342 if (!set
|| nr
> set
->queue_depth
)
2346 queue_for_each_hw_ctx(q
, hctx
, i
) {
2349 ret
= blk_mq_tag_update_depth(hctx
->tags
, nr
);
2355 q
->nr_requests
= nr
;
2360 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2362 struct request_queue
*q
;
2364 if (nr_hw_queues
> nr_cpu_ids
)
2365 nr_hw_queues
= nr_cpu_ids
;
2366 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2369 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2370 blk_mq_freeze_queue(q
);
2372 set
->nr_hw_queues
= nr_hw_queues
;
2373 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2374 blk_mq_realloc_hw_ctxs(set
, q
);
2376 if (q
->nr_hw_queues
> 1)
2377 blk_queue_make_request(q
, blk_mq_make_request
);
2379 blk_queue_make_request(q
, blk_sq_make_request
);
2381 blk_mq_queue_reinit(q
, cpu_online_mask
);
2384 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2385 blk_mq_unfreeze_queue(q
);
2387 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2389 void blk_mq_disable_hotplug(void)
2391 mutex_lock(&all_q_mutex
);
2394 void blk_mq_enable_hotplug(void)
2396 mutex_unlock(&all_q_mutex
);
2399 static int __init
blk_mq_init(void)
2403 hotcpu_notifier(blk_mq_queue_reinit_notify
, 0);
2407 subsys_initcall(blk_mq_init
);