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
, unsigned int rw_flags
)
164 if (blk_queue_io_stat(q
))
165 rw_flags
|= REQ_IO_STAT
;
167 INIT_LIST_HEAD(&rq
->queuelist
);
168 /* csd/requeue_work/fifo_time is initialized before use */
171 rq
->cmd_flags
|= rw_flags
;
172 /* do not touch atomic flags, it needs atomic ops against the timer */
174 INIT_HLIST_NODE(&rq
->hash
);
175 RB_CLEAR_NODE(&rq
->rb_node
);
178 rq
->start_time
= jiffies
;
179 #ifdef CONFIG_BLK_CGROUP
181 set_start_time_ns(rq
);
182 rq
->io_start_time_ns
= 0;
184 rq
->nr_phys_segments
= 0;
185 #if defined(CONFIG_BLK_DEV_INTEGRITY)
186 rq
->nr_integrity_segments
= 0;
189 /* tag was already set */
199 INIT_LIST_HEAD(&rq
->timeout_list
);
203 rq
->end_io_data
= NULL
;
206 ctx
->rq_dispatched
[rw_is_sync(rw_flags
)]++;
209 static struct request
*
210 __blk_mq_alloc_request(struct blk_mq_alloc_data
*data
, int rw
)
215 tag
= blk_mq_get_tag(data
);
216 if (tag
!= BLK_MQ_TAG_FAIL
) {
217 rq
= data
->hctx
->tags
->rqs
[tag
];
219 if (blk_mq_tag_busy(data
->hctx
)) {
220 rq
->cmd_flags
= REQ_MQ_INFLIGHT
;
221 atomic_inc(&data
->hctx
->nr_active
);
225 blk_mq_rq_ctx_init(data
->q
, data
->ctx
, rq
, rw
);
232 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
235 struct blk_mq_ctx
*ctx
;
236 struct blk_mq_hw_ctx
*hctx
;
238 struct blk_mq_alloc_data alloc_data
;
241 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
245 ctx
= blk_mq_get_ctx(q
);
246 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
247 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
249 rq
= __blk_mq_alloc_request(&alloc_data
, rw
);
250 if (!rq
&& !(flags
& BLK_MQ_REQ_NOWAIT
)) {
251 __blk_mq_run_hw_queue(hctx
);
254 ctx
= blk_mq_get_ctx(q
);
255 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
256 blk_mq_set_alloc_data(&alloc_data
, q
, flags
, ctx
, hctx
);
257 rq
= __blk_mq_alloc_request(&alloc_data
, rw
);
258 ctx
= alloc_data
.ctx
;
263 return ERR_PTR(-EWOULDBLOCK
);
267 EXPORT_SYMBOL(blk_mq_alloc_request
);
269 static void __blk_mq_free_request(struct blk_mq_hw_ctx
*hctx
,
270 struct blk_mq_ctx
*ctx
, struct request
*rq
)
272 const int tag
= rq
->tag
;
273 struct request_queue
*q
= rq
->q
;
275 if (rq
->cmd_flags
& REQ_MQ_INFLIGHT
)
276 atomic_dec(&hctx
->nr_active
);
279 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
280 blk_mq_put_tag(hctx
, tag
, &ctx
->last_tag
);
284 void blk_mq_free_hctx_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
286 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
288 ctx
->rq_completed
[rq_is_sync(rq
)]++;
289 __blk_mq_free_request(hctx
, ctx
, rq
);
292 EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request
);
294 void blk_mq_free_request(struct request
*rq
)
296 struct blk_mq_hw_ctx
*hctx
;
297 struct request_queue
*q
= rq
->q
;
299 hctx
= q
->mq_ops
->map_queue(q
, rq
->mq_ctx
->cpu
);
300 blk_mq_free_hctx_request(hctx
, rq
);
302 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
304 inline void __blk_mq_end_request(struct request
*rq
, int error
)
306 blk_account_io_done(rq
);
309 rq
->end_io(rq
, error
);
311 if (unlikely(blk_bidi_rq(rq
)))
312 blk_mq_free_request(rq
->next_rq
);
313 blk_mq_free_request(rq
);
316 EXPORT_SYMBOL(__blk_mq_end_request
);
318 void blk_mq_end_request(struct request
*rq
, int error
)
320 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
322 __blk_mq_end_request(rq
, error
);
324 EXPORT_SYMBOL(blk_mq_end_request
);
326 static void __blk_mq_complete_request_remote(void *data
)
328 struct request
*rq
= data
;
330 rq
->q
->softirq_done_fn(rq
);
333 static void blk_mq_ipi_complete_request(struct request
*rq
)
335 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
339 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
340 rq
->q
->softirq_done_fn(rq
);
345 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
346 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
348 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
349 rq
->csd
.func
= __blk_mq_complete_request_remote
;
352 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
354 rq
->q
->softirq_done_fn(rq
);
359 static void __blk_mq_complete_request(struct request
*rq
)
361 struct request_queue
*q
= rq
->q
;
363 if (!q
->softirq_done_fn
)
364 blk_mq_end_request(rq
, rq
->errors
);
366 blk_mq_ipi_complete_request(rq
);
370 * blk_mq_complete_request - end I/O on a request
371 * @rq: the request being processed
374 * Ends all I/O on a request. It does not handle partial completions.
375 * The actual completion happens out-of-order, through a IPI handler.
377 void blk_mq_complete_request(struct request
*rq
, int error
)
379 struct request_queue
*q
= rq
->q
;
381 if (unlikely(blk_should_fake_timeout(q
)))
383 if (!blk_mark_rq_complete(rq
)) {
385 __blk_mq_complete_request(rq
);
388 EXPORT_SYMBOL(blk_mq_complete_request
);
390 int blk_mq_request_started(struct request
*rq
)
392 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
394 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
396 void blk_mq_start_request(struct request
*rq
)
398 struct request_queue
*q
= rq
->q
;
400 trace_block_rq_issue(q
, rq
);
402 rq
->resid_len
= blk_rq_bytes(rq
);
403 if (unlikely(blk_bidi_rq(rq
)))
404 rq
->next_rq
->resid_len
= blk_rq_bytes(rq
->next_rq
);
409 * Ensure that ->deadline is visible before set the started
410 * flag and clear the completed flag.
412 smp_mb__before_atomic();
415 * Mark us as started and clear complete. Complete might have been
416 * set if requeue raced with timeout, which then marked it as
417 * complete. So be sure to clear complete again when we start
418 * the request, otherwise we'll ignore the completion event.
420 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
421 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
422 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
423 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
425 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
427 * Make sure space for the drain appears. We know we can do
428 * this because max_hw_segments has been adjusted to be one
429 * fewer than the device can handle.
431 rq
->nr_phys_segments
++;
434 EXPORT_SYMBOL(blk_mq_start_request
);
436 static void __blk_mq_requeue_request(struct request
*rq
)
438 struct request_queue
*q
= rq
->q
;
440 trace_block_rq_requeue(q
, rq
);
442 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
443 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
444 rq
->nr_phys_segments
--;
448 void blk_mq_requeue_request(struct request
*rq
)
450 __blk_mq_requeue_request(rq
);
452 BUG_ON(blk_queued_rq(rq
));
453 blk_mq_add_to_requeue_list(rq
, true);
455 EXPORT_SYMBOL(blk_mq_requeue_request
);
457 static void blk_mq_requeue_work(struct work_struct
*work
)
459 struct request_queue
*q
=
460 container_of(work
, struct request_queue
, requeue_work
);
462 struct request
*rq
, *next
;
465 spin_lock_irqsave(&q
->requeue_lock
, flags
);
466 list_splice_init(&q
->requeue_list
, &rq_list
);
467 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
469 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
470 if (!(rq
->cmd_flags
& REQ_SOFTBARRIER
))
473 rq
->cmd_flags
&= ~REQ_SOFTBARRIER
;
474 list_del_init(&rq
->queuelist
);
475 blk_mq_insert_request(rq
, true, false, false);
478 while (!list_empty(&rq_list
)) {
479 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
480 list_del_init(&rq
->queuelist
);
481 blk_mq_insert_request(rq
, false, false, false);
485 * Use the start variant of queue running here, so that running
486 * the requeue work will kick stopped queues.
488 blk_mq_start_hw_queues(q
);
491 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
)
493 struct request_queue
*q
= rq
->q
;
497 * We abuse this flag that is otherwise used by the I/O scheduler to
498 * request head insertation from the workqueue.
500 BUG_ON(rq
->cmd_flags
& REQ_SOFTBARRIER
);
502 spin_lock_irqsave(&q
->requeue_lock
, flags
);
504 rq
->cmd_flags
|= REQ_SOFTBARRIER
;
505 list_add(&rq
->queuelist
, &q
->requeue_list
);
507 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
509 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
511 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
513 void blk_mq_cancel_requeue_work(struct request_queue
*q
)
515 cancel_work_sync(&q
->requeue_work
);
517 EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work
);
519 void blk_mq_kick_requeue_list(struct request_queue
*q
)
521 kblockd_schedule_work(&q
->requeue_work
);
523 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
525 void blk_mq_abort_requeue_list(struct request_queue
*q
)
530 spin_lock_irqsave(&q
->requeue_lock
, flags
);
531 list_splice_init(&q
->requeue_list
, &rq_list
);
532 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
534 while (!list_empty(&rq_list
)) {
537 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
538 list_del_init(&rq
->queuelist
);
540 blk_mq_end_request(rq
, rq
->errors
);
543 EXPORT_SYMBOL(blk_mq_abort_requeue_list
);
545 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
547 return tags
->rqs
[tag
];
549 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
551 struct blk_mq_timeout_data
{
553 unsigned int next_set
;
556 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
558 struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
559 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
562 * We know that complete is set at this point. If STARTED isn't set
563 * anymore, then the request isn't active and the "timeout" should
564 * just be ignored. This can happen due to the bitflag ordering.
565 * Timeout first checks if STARTED is set, and if it is, assumes
566 * the request is active. But if we race with completion, then
567 * we both flags will get cleared. So check here again, and ignore
568 * a timeout event with a request that isn't active.
570 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
574 ret
= ops
->timeout(req
, reserved
);
578 __blk_mq_complete_request(req
);
580 case BLK_EH_RESET_TIMER
:
582 blk_clear_rq_complete(req
);
584 case BLK_EH_NOT_HANDLED
:
587 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
592 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
593 struct request
*rq
, void *priv
, bool reserved
)
595 struct blk_mq_timeout_data
*data
= priv
;
597 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
599 * If a request wasn't started before the queue was
600 * marked dying, kill it here or it'll go unnoticed.
602 if (unlikely(blk_queue_dying(rq
->q
))) {
604 blk_mq_end_request(rq
, rq
->errors
);
608 if (rq
->cmd_flags
& REQ_NO_TIMEOUT
)
611 if (time_after_eq(jiffies
, rq
->deadline
)) {
612 if (!blk_mark_rq_complete(rq
))
613 blk_mq_rq_timed_out(rq
, reserved
);
614 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
615 data
->next
= rq
->deadline
;
620 static void blk_mq_timeout_work(struct work_struct
*work
)
622 struct request_queue
*q
=
623 container_of(work
, struct request_queue
, timeout_work
);
624 struct blk_mq_timeout_data data
= {
630 if (blk_queue_enter(q
, true))
633 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
636 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
637 mod_timer(&q
->timeout
, data
.next
);
639 struct blk_mq_hw_ctx
*hctx
;
641 queue_for_each_hw_ctx(q
, hctx
, i
) {
642 /* the hctx may be unmapped, so check it here */
643 if (blk_mq_hw_queue_mapped(hctx
))
644 blk_mq_tag_idle(hctx
);
651 * Reverse check our software queue for entries that we could potentially
652 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
653 * too much time checking for merges.
655 static bool blk_mq_attempt_merge(struct request_queue
*q
,
656 struct blk_mq_ctx
*ctx
, struct bio
*bio
)
661 list_for_each_entry_reverse(rq
, &ctx
->rq_list
, queuelist
) {
667 if (!blk_rq_merge_ok(rq
, bio
))
670 el_ret
= blk_try_merge(rq
, bio
);
671 if (el_ret
== ELEVATOR_BACK_MERGE
) {
672 if (bio_attempt_back_merge(q
, rq
, bio
)) {
677 } else if (el_ret
== ELEVATOR_FRONT_MERGE
) {
678 if (bio_attempt_front_merge(q
, rq
, bio
)) {
690 * Process software queues that have been marked busy, splicing them
691 * to the for-dispatch
693 static void flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
695 struct blk_mq_ctx
*ctx
;
698 for (i
= 0; i
< hctx
->ctx_map
.size
; i
++) {
699 struct blk_align_bitmap
*bm
= &hctx
->ctx_map
.map
[i
];
700 unsigned int off
, bit
;
706 off
= i
* hctx
->ctx_map
.bits_per_word
;
708 bit
= find_next_bit(&bm
->word
, bm
->depth
, bit
);
709 if (bit
>= bm
->depth
)
712 ctx
= hctx
->ctxs
[bit
+ off
];
713 clear_bit(bit
, &bm
->word
);
714 spin_lock(&ctx
->lock
);
715 list_splice_tail_init(&ctx
->rq_list
, list
);
716 spin_unlock(&ctx
->lock
);
724 * Run this hardware queue, pulling any software queues mapped to it in.
725 * Note that this function currently has various problems around ordering
726 * of IO. In particular, we'd like FIFO behaviour on handling existing
727 * items on the hctx->dispatch list. Ignore that for now.
729 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
731 struct request_queue
*q
= hctx
->queue
;
734 LIST_HEAD(driver_list
);
735 struct list_head
*dptr
;
738 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
));
740 if (unlikely(test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)))
746 * Touch any software queue that has pending entries.
748 flush_busy_ctxs(hctx
, &rq_list
);
751 * If we have previous entries on our dispatch list, grab them
752 * and stuff them at the front for more fair dispatch.
754 if (!list_empty_careful(&hctx
->dispatch
)) {
755 spin_lock(&hctx
->lock
);
756 if (!list_empty(&hctx
->dispatch
))
757 list_splice_init(&hctx
->dispatch
, &rq_list
);
758 spin_unlock(&hctx
->lock
);
762 * Start off with dptr being NULL, so we start the first request
763 * immediately, even if we have more pending.
768 * Now process all the entries, sending them to the driver.
771 while (!list_empty(&rq_list
)) {
772 struct blk_mq_queue_data bd
;
775 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
776 list_del_init(&rq
->queuelist
);
780 bd
.last
= list_empty(&rq_list
);
782 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
784 case BLK_MQ_RQ_QUEUE_OK
:
787 case BLK_MQ_RQ_QUEUE_BUSY
:
788 list_add(&rq
->queuelist
, &rq_list
);
789 __blk_mq_requeue_request(rq
);
792 pr_err("blk-mq: bad return on queue: %d\n", ret
);
793 case BLK_MQ_RQ_QUEUE_ERROR
:
795 blk_mq_end_request(rq
, rq
->errors
);
799 if (ret
== BLK_MQ_RQ_QUEUE_BUSY
)
803 * We've done the first request. If we have more than 1
804 * left in the list, set dptr to defer issue.
806 if (!dptr
&& rq_list
.next
!= rq_list
.prev
)
811 hctx
->dispatched
[0]++;
812 else if (queued
< (1 << (BLK_MQ_MAX_DISPATCH_ORDER
- 1)))
813 hctx
->dispatched
[ilog2(queued
) + 1]++;
816 * Any items that need requeuing? Stuff them into hctx->dispatch,
817 * that is where we will continue on next queue run.
819 if (!list_empty(&rq_list
)) {
820 spin_lock(&hctx
->lock
);
821 list_splice(&rq_list
, &hctx
->dispatch
);
822 spin_unlock(&hctx
->lock
);
824 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
825 * it's possible the queue is stopped and restarted again
826 * before this. Queue restart will dispatch requests. And since
827 * requests in rq_list aren't added into hctx->dispatch yet,
828 * the requests in rq_list might get lost.
830 * blk_mq_run_hw_queue() already checks the STOPPED bit
832 blk_mq_run_hw_queue(hctx
, true);
837 * It'd be great if the workqueue API had a way to pass
838 * in a mask and had some smarts for more clever placement.
839 * For now we just round-robin here, switching for every
840 * BLK_MQ_CPU_WORK_BATCH queued items.
842 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
844 if (hctx
->queue
->nr_hw_queues
== 1)
845 return WORK_CPU_UNBOUND
;
847 if (--hctx
->next_cpu_batch
<= 0) {
848 int cpu
= hctx
->next_cpu
, next_cpu
;
850 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
851 if (next_cpu
>= nr_cpu_ids
)
852 next_cpu
= cpumask_first(hctx
->cpumask
);
854 hctx
->next_cpu
= next_cpu
;
855 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
860 return hctx
->next_cpu
;
863 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
865 if (unlikely(test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
) ||
866 !blk_mq_hw_queue_mapped(hctx
)))
871 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
872 __blk_mq_run_hw_queue(hctx
);
880 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
884 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
886 struct blk_mq_hw_ctx
*hctx
;
889 queue_for_each_hw_ctx(q
, hctx
, i
) {
890 if ((!blk_mq_hctx_has_pending(hctx
) &&
891 list_empty_careful(&hctx
->dispatch
)) ||
892 test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
895 blk_mq_run_hw_queue(hctx
, async
);
898 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
900 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
902 cancel_delayed_work(&hctx
->run_work
);
903 cancel_delayed_work(&hctx
->delay_work
);
904 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
906 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
908 void blk_mq_stop_hw_queues(struct request_queue
*q
)
910 struct blk_mq_hw_ctx
*hctx
;
913 queue_for_each_hw_ctx(q
, hctx
, i
)
914 blk_mq_stop_hw_queue(hctx
);
916 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
918 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
920 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
922 blk_mq_run_hw_queue(hctx
, false);
924 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
926 void blk_mq_start_hw_queues(struct request_queue
*q
)
928 struct blk_mq_hw_ctx
*hctx
;
931 queue_for_each_hw_ctx(q
, hctx
, i
)
932 blk_mq_start_hw_queue(hctx
);
934 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
936 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
938 struct blk_mq_hw_ctx
*hctx
;
941 queue_for_each_hw_ctx(q
, hctx
, i
) {
942 if (!test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
945 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
946 blk_mq_run_hw_queue(hctx
, async
);
949 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
951 static void blk_mq_run_work_fn(struct work_struct
*work
)
953 struct blk_mq_hw_ctx
*hctx
;
955 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
957 __blk_mq_run_hw_queue(hctx
);
960 static void blk_mq_delay_work_fn(struct work_struct
*work
)
962 struct blk_mq_hw_ctx
*hctx
;
964 hctx
= container_of(work
, struct blk_mq_hw_ctx
, delay_work
.work
);
966 if (test_and_clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
967 __blk_mq_run_hw_queue(hctx
);
970 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
972 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
975 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
976 &hctx
->delay_work
, msecs_to_jiffies(msecs
));
978 EXPORT_SYMBOL(blk_mq_delay_queue
);
980 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
981 struct blk_mq_ctx
*ctx
,
985 trace_block_rq_insert(hctx
->queue
, rq
);
988 list_add(&rq
->queuelist
, &ctx
->rq_list
);
990 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
993 static void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
,
994 struct request
*rq
, bool at_head
)
996 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
998 __blk_mq_insert_req_list(hctx
, ctx
, rq
, at_head
);
999 blk_mq_hctx_mark_pending(hctx
, ctx
);
1002 void blk_mq_insert_request(struct request
*rq
, bool at_head
, bool run_queue
,
1005 struct request_queue
*q
= rq
->q
;
1006 struct blk_mq_hw_ctx
*hctx
;
1007 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
, *current_ctx
;
1009 current_ctx
= blk_mq_get_ctx(q
);
1010 if (!cpu_online(ctx
->cpu
))
1011 rq
->mq_ctx
= ctx
= current_ctx
;
1013 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1015 spin_lock(&ctx
->lock
);
1016 __blk_mq_insert_request(hctx
, rq
, at_head
);
1017 spin_unlock(&ctx
->lock
);
1020 blk_mq_run_hw_queue(hctx
, async
);
1022 blk_mq_put_ctx(current_ctx
);
1025 static void blk_mq_insert_requests(struct request_queue
*q
,
1026 struct blk_mq_ctx
*ctx
,
1027 struct list_head
*list
,
1032 struct blk_mq_hw_ctx
*hctx
;
1033 struct blk_mq_ctx
*current_ctx
;
1035 trace_block_unplug(q
, depth
, !from_schedule
);
1037 current_ctx
= blk_mq_get_ctx(q
);
1039 if (!cpu_online(ctx
->cpu
))
1041 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1044 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1047 spin_lock(&ctx
->lock
);
1048 while (!list_empty(list
)) {
1051 rq
= list_first_entry(list
, struct request
, queuelist
);
1052 list_del_init(&rq
->queuelist
);
1054 __blk_mq_insert_req_list(hctx
, ctx
, rq
, false);
1056 blk_mq_hctx_mark_pending(hctx
, ctx
);
1057 spin_unlock(&ctx
->lock
);
1059 blk_mq_run_hw_queue(hctx
, from_schedule
);
1060 blk_mq_put_ctx(current_ctx
);
1063 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1065 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1066 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1068 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1069 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1070 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1073 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1075 struct blk_mq_ctx
*this_ctx
;
1076 struct request_queue
*this_q
;
1079 LIST_HEAD(ctx_list
);
1082 list_splice_init(&plug
->mq_list
, &list
);
1084 list_sort(NULL
, &list
, plug_ctx_cmp
);
1090 while (!list_empty(&list
)) {
1091 rq
= list_entry_rq(list
.next
);
1092 list_del_init(&rq
->queuelist
);
1094 if (rq
->mq_ctx
!= this_ctx
) {
1096 blk_mq_insert_requests(this_q
, this_ctx
,
1101 this_ctx
= rq
->mq_ctx
;
1107 list_add_tail(&rq
->queuelist
, &ctx_list
);
1111 * If 'this_ctx' is set, we know we have entries to complete
1112 * on 'ctx_list'. Do those.
1115 blk_mq_insert_requests(this_q
, this_ctx
, &ctx_list
, depth
,
1120 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1122 init_request_from_bio(rq
, bio
);
1124 if (blk_do_io_stat(rq
))
1125 blk_account_io_start(rq
, 1);
1128 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1130 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1131 !blk_queue_nomerges(hctx
->queue
);
1134 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx
*hctx
,
1135 struct blk_mq_ctx
*ctx
,
1136 struct request
*rq
, struct bio
*bio
)
1138 if (!hctx_allow_merges(hctx
) || !bio_mergeable(bio
)) {
1139 blk_mq_bio_to_request(rq
, bio
);
1140 spin_lock(&ctx
->lock
);
1142 __blk_mq_insert_request(hctx
, rq
, false);
1143 spin_unlock(&ctx
->lock
);
1146 struct request_queue
*q
= hctx
->queue
;
1148 spin_lock(&ctx
->lock
);
1149 if (!blk_mq_attempt_merge(q
, ctx
, bio
)) {
1150 blk_mq_bio_to_request(rq
, bio
);
1154 spin_unlock(&ctx
->lock
);
1155 __blk_mq_free_request(hctx
, ctx
, rq
);
1160 struct blk_map_ctx
{
1161 struct blk_mq_hw_ctx
*hctx
;
1162 struct blk_mq_ctx
*ctx
;
1165 static struct request
*blk_mq_map_request(struct request_queue
*q
,
1167 struct blk_map_ctx
*data
)
1169 struct blk_mq_hw_ctx
*hctx
;
1170 struct blk_mq_ctx
*ctx
;
1172 int rw
= bio_data_dir(bio
);
1173 struct blk_mq_alloc_data alloc_data
;
1175 blk_queue_enter_live(q
);
1176 ctx
= blk_mq_get_ctx(q
);
1177 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1179 if (rw_is_sync(bio
->bi_rw
))
1182 trace_block_getrq(q
, bio
, rw
);
1183 blk_mq_set_alloc_data(&alloc_data
, q
, BLK_MQ_REQ_NOWAIT
, ctx
, hctx
);
1184 rq
= __blk_mq_alloc_request(&alloc_data
, rw
);
1185 if (unlikely(!rq
)) {
1186 __blk_mq_run_hw_queue(hctx
);
1187 blk_mq_put_ctx(ctx
);
1188 trace_block_sleeprq(q
, bio
, rw
);
1190 ctx
= blk_mq_get_ctx(q
);
1191 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1192 blk_mq_set_alloc_data(&alloc_data
, q
, 0, ctx
, hctx
);
1193 rq
= __blk_mq_alloc_request(&alloc_data
, rw
);
1194 ctx
= alloc_data
.ctx
;
1195 hctx
= alloc_data
.hctx
;
1204 static int blk_mq_direct_issue_request(struct request
*rq
, blk_qc_t
*cookie
)
1207 struct request_queue
*q
= rq
->q
;
1208 struct blk_mq_hw_ctx
*hctx
= q
->mq_ops
->map_queue(q
,
1210 struct blk_mq_queue_data bd
= {
1215 blk_qc_t new_cookie
= blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
);
1218 * For OK queue, we are done. For error, kill it. Any other
1219 * error (busy), just add it to our list as we previously
1222 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1223 if (ret
== BLK_MQ_RQ_QUEUE_OK
) {
1224 *cookie
= new_cookie
;
1228 __blk_mq_requeue_request(rq
);
1230 if (ret
== BLK_MQ_RQ_QUEUE_ERROR
) {
1231 *cookie
= BLK_QC_T_NONE
;
1233 blk_mq_end_request(rq
, rq
->errors
);
1241 * Multiple hardware queue variant. This will not use per-process plugs,
1242 * but will attempt to bypass the hctx queueing if we can go straight to
1243 * hardware for SYNC IO.
1245 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1247 const int is_sync
= rw_is_sync(bio
->bi_rw
);
1248 const int is_flush_fua
= bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
);
1249 struct blk_map_ctx data
;
1251 unsigned int request_count
= 0;
1252 struct blk_plug
*plug
;
1253 struct request
*same_queue_rq
= NULL
;
1256 blk_queue_bounce(q
, &bio
);
1258 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1260 return BLK_QC_T_NONE
;
1263 blk_queue_split(q
, &bio
, q
->bio_split
);
1265 if (!is_flush_fua
&& !blk_queue_nomerges(q
)) {
1266 if (blk_attempt_plug_merge(q
, bio
, &request_count
,
1268 return BLK_QC_T_NONE
;
1270 request_count
= blk_plug_queued_count(q
);
1272 rq
= blk_mq_map_request(q
, bio
, &data
);
1274 return BLK_QC_T_NONE
;
1276 cookie
= blk_tag_to_qc_t(rq
->tag
, data
.hctx
->queue_num
);
1278 if (unlikely(is_flush_fua
)) {
1279 blk_mq_bio_to_request(rq
, bio
);
1280 blk_insert_flush(rq
);
1284 plug
= current
->plug
;
1286 * If the driver supports defer issued based on 'last', then
1287 * queue it up like normal since we can potentially save some
1290 if (((plug
&& !blk_queue_nomerges(q
)) || is_sync
) &&
1291 !(data
.hctx
->flags
& BLK_MQ_F_DEFER_ISSUE
)) {
1292 struct request
*old_rq
= NULL
;
1294 blk_mq_bio_to_request(rq
, bio
);
1297 * We do limited pluging. If the bio can be merged, do that.
1298 * Otherwise the existing request in the plug list will be
1299 * issued. So the plug list will have one request at most
1303 * The plug list might get flushed before this. If that
1304 * happens, same_queue_rq is invalid and plug list is
1307 if (same_queue_rq
&& !list_empty(&plug
->mq_list
)) {
1308 old_rq
= same_queue_rq
;
1309 list_del_init(&old_rq
->queuelist
);
1311 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1312 } else /* is_sync */
1314 blk_mq_put_ctx(data
.ctx
);
1317 if (!blk_mq_direct_issue_request(old_rq
, &cookie
))
1319 blk_mq_insert_request(old_rq
, false, true, true);
1323 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1325 * For a SYNC request, send it to the hardware immediately. For
1326 * an ASYNC request, just ensure that we run it later on. The
1327 * latter allows for merging opportunities and more efficient
1331 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1333 blk_mq_put_ctx(data
.ctx
);
1339 * Single hardware queue variant. This will attempt to use any per-process
1340 * plug for merging and IO deferral.
1342 static blk_qc_t
blk_sq_make_request(struct request_queue
*q
, struct bio
*bio
)
1344 const int is_sync
= rw_is_sync(bio
->bi_rw
);
1345 const int is_flush_fua
= bio
->bi_rw
& (REQ_FLUSH
| REQ_FUA
);
1346 struct blk_plug
*plug
;
1347 unsigned int request_count
= 0;
1348 struct blk_map_ctx data
;
1352 blk_queue_bounce(q
, &bio
);
1354 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1356 return BLK_QC_T_NONE
;
1359 blk_queue_split(q
, &bio
, q
->bio_split
);
1361 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1362 blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1363 return BLK_QC_T_NONE
;
1365 rq
= blk_mq_map_request(q
, bio
, &data
);
1367 return BLK_QC_T_NONE
;
1369 cookie
= blk_tag_to_qc_t(rq
->tag
, data
.hctx
->queue_num
);
1371 if (unlikely(is_flush_fua
)) {
1372 blk_mq_bio_to_request(rq
, bio
);
1373 blk_insert_flush(rq
);
1378 * A task plug currently exists. Since this is completely lockless,
1379 * utilize that to temporarily store requests until the task is
1380 * either done or scheduled away.
1382 plug
= current
->plug
;
1384 blk_mq_bio_to_request(rq
, bio
);
1386 trace_block_plug(q
);
1388 blk_mq_put_ctx(data
.ctx
);
1390 if (request_count
>= BLK_MAX_REQUEST_COUNT
) {
1391 blk_flush_plug_list(plug
, false);
1392 trace_block_plug(q
);
1395 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1399 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1401 * For a SYNC request, send it to the hardware immediately. For
1402 * an ASYNC request, just ensure that we run it later on. The
1403 * latter allows for merging opportunities and more efficient
1407 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1410 blk_mq_put_ctx(data
.ctx
);
1415 * Default mapping to a software queue, since we use one per CPU.
1417 struct blk_mq_hw_ctx
*blk_mq_map_queue(struct request_queue
*q
, const int cpu
)
1419 return q
->queue_hw_ctx
[q
->mq_map
[cpu
]];
1421 EXPORT_SYMBOL(blk_mq_map_queue
);
1423 static void blk_mq_free_rq_map(struct blk_mq_tag_set
*set
,
1424 struct blk_mq_tags
*tags
, unsigned int hctx_idx
)
1428 if (tags
->rqs
&& set
->ops
->exit_request
) {
1431 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1434 set
->ops
->exit_request(set
->driver_data
, tags
->rqs
[i
],
1436 tags
->rqs
[i
] = NULL
;
1440 while (!list_empty(&tags
->page_list
)) {
1441 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1442 list_del_init(&page
->lru
);
1444 * Remove kmemleak object previously allocated in
1445 * blk_mq_init_rq_map().
1447 kmemleak_free(page_address(page
));
1448 __free_pages(page
, page
->private);
1453 blk_mq_free_tags(tags
);
1456 static size_t order_to_size(unsigned int order
)
1458 return (size_t)PAGE_SIZE
<< order
;
1461 static struct blk_mq_tags
*blk_mq_init_rq_map(struct blk_mq_tag_set
*set
,
1462 unsigned int hctx_idx
)
1464 struct blk_mq_tags
*tags
;
1465 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1466 size_t rq_size
, left
;
1468 tags
= blk_mq_init_tags(set
->queue_depth
, set
->reserved_tags
,
1470 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1474 INIT_LIST_HEAD(&tags
->page_list
);
1476 tags
->rqs
= kzalloc_node(set
->queue_depth
* sizeof(struct request
*),
1477 GFP_KERNEL
| __GFP_NOWARN
| __GFP_NORETRY
,
1480 blk_mq_free_tags(tags
);
1485 * rq_size is the size of the request plus driver payload, rounded
1486 * to the cacheline size
1488 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1490 left
= rq_size
* set
->queue_depth
;
1492 for (i
= 0; i
< set
->queue_depth
; ) {
1493 int this_order
= max_order
;
1498 while (left
< order_to_size(this_order
- 1) && this_order
)
1502 page
= alloc_pages_node(set
->numa_node
,
1503 GFP_KERNEL
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1509 if (order_to_size(this_order
) < rq_size
)
1516 page
->private = this_order
;
1517 list_add_tail(&page
->lru
, &tags
->page_list
);
1519 p
= page_address(page
);
1521 * Allow kmemleak to scan these pages as they contain pointers
1522 * to additional allocations like via ops->init_request().
1524 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_KERNEL
);
1525 entries_per_page
= order_to_size(this_order
) / rq_size
;
1526 to_do
= min(entries_per_page
, set
->queue_depth
- i
);
1527 left
-= to_do
* rq_size
;
1528 for (j
= 0; j
< to_do
; j
++) {
1530 if (set
->ops
->init_request
) {
1531 if (set
->ops
->init_request(set
->driver_data
,
1532 tags
->rqs
[i
], hctx_idx
, i
,
1534 tags
->rqs
[i
] = NULL
;
1546 blk_mq_free_rq_map(set
, tags
, hctx_idx
);
1550 static void blk_mq_free_bitmap(struct blk_mq_ctxmap
*bitmap
)
1555 static int blk_mq_alloc_bitmap(struct blk_mq_ctxmap
*bitmap
, int node
)
1557 unsigned int bpw
= 8, total
, num_maps
, i
;
1559 bitmap
->bits_per_word
= bpw
;
1561 num_maps
= ALIGN(nr_cpu_ids
, bpw
) / bpw
;
1562 bitmap
->map
= kzalloc_node(num_maps
* sizeof(struct blk_align_bitmap
),
1568 for (i
= 0; i
< num_maps
; i
++) {
1569 bitmap
->map
[i
].depth
= min(total
, bitmap
->bits_per_word
);
1570 total
-= bitmap
->map
[i
].depth
;
1576 static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx
*hctx
, int cpu
)
1578 struct request_queue
*q
= hctx
->queue
;
1579 struct blk_mq_ctx
*ctx
;
1583 * Move ctx entries to new CPU, if this one is going away.
1585 ctx
= __blk_mq_get_ctx(q
, cpu
);
1587 spin_lock(&ctx
->lock
);
1588 if (!list_empty(&ctx
->rq_list
)) {
1589 list_splice_init(&ctx
->rq_list
, &tmp
);
1590 blk_mq_hctx_clear_pending(hctx
, ctx
);
1592 spin_unlock(&ctx
->lock
);
1594 if (list_empty(&tmp
))
1597 ctx
= blk_mq_get_ctx(q
);
1598 spin_lock(&ctx
->lock
);
1600 while (!list_empty(&tmp
)) {
1603 rq
= list_first_entry(&tmp
, struct request
, queuelist
);
1605 list_move_tail(&rq
->queuelist
, &ctx
->rq_list
);
1608 hctx
= q
->mq_ops
->map_queue(q
, ctx
->cpu
);
1609 blk_mq_hctx_mark_pending(hctx
, ctx
);
1611 spin_unlock(&ctx
->lock
);
1613 blk_mq_run_hw_queue(hctx
, true);
1614 blk_mq_put_ctx(ctx
);
1618 static int blk_mq_hctx_notify(void *data
, unsigned long action
,
1621 struct blk_mq_hw_ctx
*hctx
= data
;
1623 if (action
== CPU_DEAD
|| action
== CPU_DEAD_FROZEN
)
1624 return blk_mq_hctx_cpu_offline(hctx
, cpu
);
1627 * In case of CPU online, tags may be reallocated
1628 * in blk_mq_map_swqueue() after mapping is updated.
1634 /* hctx->ctxs will be freed in queue's release handler */
1635 static void blk_mq_exit_hctx(struct request_queue
*q
,
1636 struct blk_mq_tag_set
*set
,
1637 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1639 unsigned flush_start_tag
= set
->queue_depth
;
1641 blk_mq_tag_idle(hctx
);
1643 if (set
->ops
->exit_request
)
1644 set
->ops
->exit_request(set
->driver_data
,
1645 hctx
->fq
->flush_rq
, hctx_idx
,
1646 flush_start_tag
+ hctx_idx
);
1648 if (set
->ops
->exit_hctx
)
1649 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1651 blk_mq_unregister_cpu_notifier(&hctx
->cpu_notifier
);
1652 blk_free_flush_queue(hctx
->fq
);
1653 blk_mq_free_bitmap(&hctx
->ctx_map
);
1656 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1657 struct blk_mq_tag_set
*set
, int nr_queue
)
1659 struct blk_mq_hw_ctx
*hctx
;
1662 queue_for_each_hw_ctx(q
, hctx
, i
) {
1665 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1669 static void blk_mq_free_hw_queues(struct request_queue
*q
,
1670 struct blk_mq_tag_set
*set
)
1672 struct blk_mq_hw_ctx
*hctx
;
1675 queue_for_each_hw_ctx(q
, hctx
, i
)
1676 free_cpumask_var(hctx
->cpumask
);
1679 static int blk_mq_init_hctx(struct request_queue
*q
,
1680 struct blk_mq_tag_set
*set
,
1681 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1684 unsigned flush_start_tag
= set
->queue_depth
;
1686 node
= hctx
->numa_node
;
1687 if (node
== NUMA_NO_NODE
)
1688 node
= hctx
->numa_node
= set
->numa_node
;
1690 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1691 INIT_DELAYED_WORK(&hctx
->delay_work
, blk_mq_delay_work_fn
);
1692 spin_lock_init(&hctx
->lock
);
1693 INIT_LIST_HEAD(&hctx
->dispatch
);
1695 hctx
->queue_num
= hctx_idx
;
1696 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1698 blk_mq_init_cpu_notifier(&hctx
->cpu_notifier
,
1699 blk_mq_hctx_notify
, hctx
);
1700 blk_mq_register_cpu_notifier(&hctx
->cpu_notifier
);
1702 hctx
->tags
= set
->tags
[hctx_idx
];
1705 * Allocate space for all possible cpus to avoid allocation at
1708 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1711 goto unregister_cpu_notifier
;
1713 if (blk_mq_alloc_bitmap(&hctx
->ctx_map
, node
))
1718 if (set
->ops
->init_hctx
&&
1719 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1722 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
1726 if (set
->ops
->init_request
&&
1727 set
->ops
->init_request(set
->driver_data
,
1728 hctx
->fq
->flush_rq
, hctx_idx
,
1729 flush_start_tag
+ hctx_idx
, node
))
1737 if (set
->ops
->exit_hctx
)
1738 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1740 blk_mq_free_bitmap(&hctx
->ctx_map
);
1743 unregister_cpu_notifier
:
1744 blk_mq_unregister_cpu_notifier(&hctx
->cpu_notifier
);
1749 static int blk_mq_init_hw_queues(struct request_queue
*q
,
1750 struct blk_mq_tag_set
*set
)
1752 struct blk_mq_hw_ctx
*hctx
;
1756 * Initialize hardware queues
1758 queue_for_each_hw_ctx(q
, hctx
, i
) {
1759 if (blk_mq_init_hctx(q
, set
, hctx
, i
))
1763 if (i
== q
->nr_hw_queues
)
1769 blk_mq_exit_hw_queues(q
, set
, i
);
1774 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
1775 unsigned int nr_hw_queues
)
1779 for_each_possible_cpu(i
) {
1780 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1781 struct blk_mq_hw_ctx
*hctx
;
1783 memset(__ctx
, 0, sizeof(*__ctx
));
1785 spin_lock_init(&__ctx
->lock
);
1786 INIT_LIST_HEAD(&__ctx
->rq_list
);
1789 /* If the cpu isn't online, the cpu is mapped to first hctx */
1793 hctx
= q
->mq_ops
->map_queue(q
, i
);
1796 * Set local node, IFF we have more than one hw queue. If
1797 * not, we remain on the home node of the device
1799 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
1800 hctx
->numa_node
= cpu_to_node(i
);
1804 static void blk_mq_map_swqueue(struct request_queue
*q
,
1805 const struct cpumask
*online_mask
)
1808 struct blk_mq_hw_ctx
*hctx
;
1809 struct blk_mq_ctx
*ctx
;
1810 struct blk_mq_tag_set
*set
= q
->tag_set
;
1813 * Avoid others reading imcomplete hctx->cpumask through sysfs
1815 mutex_lock(&q
->sysfs_lock
);
1817 queue_for_each_hw_ctx(q
, hctx
, i
) {
1818 cpumask_clear(hctx
->cpumask
);
1823 * Map software to hardware queues
1825 for_each_possible_cpu(i
) {
1826 /* If the cpu isn't online, the cpu is mapped to first hctx */
1827 if (!cpumask_test_cpu(i
, online_mask
))
1830 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1831 hctx
= q
->mq_ops
->map_queue(q
, i
);
1832 cpumask_set_cpu(i
, hctx
->cpumask
);
1833 ctx
->index_hw
= hctx
->nr_ctx
;
1834 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
1837 mutex_unlock(&q
->sysfs_lock
);
1839 queue_for_each_hw_ctx(q
, hctx
, i
) {
1840 struct blk_mq_ctxmap
*map
= &hctx
->ctx_map
;
1843 * If no software queues are mapped to this hardware queue,
1844 * disable it and free the request entries.
1846 if (!hctx
->nr_ctx
) {
1848 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
1849 set
->tags
[i
] = NULL
;
1855 /* unmapped hw queue can be remapped after CPU topo changed */
1857 set
->tags
[i
] = blk_mq_init_rq_map(set
, i
);
1858 hctx
->tags
= set
->tags
[i
];
1859 WARN_ON(!hctx
->tags
);
1861 cpumask_copy(hctx
->tags
->cpumask
, hctx
->cpumask
);
1863 * Set the map size to the number of mapped software queues.
1864 * This is more accurate and more efficient than looping
1865 * over all possibly mapped software queues.
1867 map
->size
= DIV_ROUND_UP(hctx
->nr_ctx
, map
->bits_per_word
);
1870 * Initialize batch roundrobin counts
1872 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
1873 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1877 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
1879 struct blk_mq_hw_ctx
*hctx
;
1882 queue_for_each_hw_ctx(q
, hctx
, i
) {
1884 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
1886 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
1890 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
1892 struct request_queue
*q
;
1894 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
1895 blk_mq_freeze_queue(q
);
1896 queue_set_hctx_shared(q
, shared
);
1897 blk_mq_unfreeze_queue(q
);
1901 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
1903 struct blk_mq_tag_set
*set
= q
->tag_set
;
1905 mutex_lock(&set
->tag_list_lock
);
1906 list_del_init(&q
->tag_set_list
);
1907 if (list_is_singular(&set
->tag_list
)) {
1908 /* just transitioned to unshared */
1909 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
1910 /* update existing queue */
1911 blk_mq_update_tag_set_depth(set
, false);
1913 mutex_unlock(&set
->tag_list_lock
);
1916 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
1917 struct request_queue
*q
)
1921 mutex_lock(&set
->tag_list_lock
);
1923 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
1924 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1925 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
1926 /* update existing queue */
1927 blk_mq_update_tag_set_depth(set
, true);
1929 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
1930 queue_set_hctx_shared(q
, true);
1931 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
1933 mutex_unlock(&set
->tag_list_lock
);
1937 * It is the actual release handler for mq, but we do it from
1938 * request queue's release handler for avoiding use-after-free
1939 * and headache because q->mq_kobj shouldn't have been introduced,
1940 * but we can't group ctx/kctx kobj without it.
1942 void blk_mq_release(struct request_queue
*q
)
1944 struct blk_mq_hw_ctx
*hctx
;
1947 /* hctx kobj stays in hctx */
1948 queue_for_each_hw_ctx(q
, hctx
, i
) {
1958 kfree(q
->queue_hw_ctx
);
1960 /* ctx kobj stays in queue_ctx */
1961 free_percpu(q
->queue_ctx
);
1964 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
1966 struct request_queue
*uninit_q
, *q
;
1968 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
1970 return ERR_PTR(-ENOMEM
);
1972 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
1974 blk_cleanup_queue(uninit_q
);
1978 EXPORT_SYMBOL(blk_mq_init_queue
);
1980 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
1981 struct request_queue
*q
)
1983 struct blk_mq_hw_ctx
**hctxs
;
1984 struct blk_mq_ctx __percpu
*ctx
;
1988 ctx
= alloc_percpu(struct blk_mq_ctx
);
1990 return ERR_PTR(-ENOMEM
);
1992 hctxs
= kmalloc_node(set
->nr_hw_queues
* sizeof(*hctxs
), GFP_KERNEL
,
1998 map
= blk_mq_make_queue_map(set
);
2002 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2003 int node
= blk_mq_hw_queue_to_node(map
, i
);
2005 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
2010 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2014 atomic_set(&hctxs
[i
]->nr_active
, 0);
2015 hctxs
[i
]->numa_node
= node
;
2016 hctxs
[i
]->queue_num
= i
;
2019 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2020 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2022 q
->nr_queues
= nr_cpu_ids
;
2023 q
->nr_hw_queues
= set
->nr_hw_queues
;
2027 q
->queue_hw_ctx
= hctxs
;
2029 q
->mq_ops
= set
->ops
;
2030 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2032 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2033 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2035 q
->sg_reserved_size
= INT_MAX
;
2037 INIT_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2038 INIT_LIST_HEAD(&q
->requeue_list
);
2039 spin_lock_init(&q
->requeue_lock
);
2041 if (q
->nr_hw_queues
> 1)
2042 blk_queue_make_request(q
, blk_mq_make_request
);
2044 blk_queue_make_request(q
, blk_sq_make_request
);
2047 * Do this after blk_queue_make_request() overrides it...
2049 q
->nr_requests
= set
->queue_depth
;
2051 if (set
->ops
->complete
)
2052 blk_queue_softirq_done(q
, set
->ops
->complete
);
2054 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2056 if (blk_mq_init_hw_queues(q
, set
))
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
);
2073 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2076 free_cpumask_var(hctxs
[i
]->cpumask
);
2083 return ERR_PTR(-ENOMEM
);
2085 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2087 void blk_mq_free_queue(struct request_queue
*q
)
2089 struct blk_mq_tag_set
*set
= q
->tag_set
;
2091 mutex_lock(&all_q_mutex
);
2092 list_del_init(&q
->all_q_node
);
2093 mutex_unlock(&all_q_mutex
);
2095 blk_mq_del_queue_tag_set(q
);
2097 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2098 blk_mq_free_hw_queues(q
, set
);
2101 /* Basically redo blk_mq_init_queue with queue frozen */
2102 static void blk_mq_queue_reinit(struct request_queue
*q
,
2103 const struct cpumask
*online_mask
)
2105 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2107 blk_mq_sysfs_unregister(q
);
2109 blk_mq_update_queue_map(q
->mq_map
, q
->nr_hw_queues
, online_mask
);
2112 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2113 * we should change hctx numa_node according to new topology (this
2114 * involves free and re-allocate memory, worthy doing?)
2117 blk_mq_map_swqueue(q
, online_mask
);
2119 blk_mq_sysfs_register(q
);
2122 static int blk_mq_queue_reinit_notify(struct notifier_block
*nb
,
2123 unsigned long action
, void *hcpu
)
2125 struct request_queue
*q
;
2126 int cpu
= (unsigned long)hcpu
;
2128 * New online cpumask which is going to be set in this hotplug event.
2129 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2130 * one-by-one and dynamically allocating this could result in a failure.
2132 static struct cpumask online_new
;
2135 * Before hotadded cpu starts handling requests, new mappings must
2136 * be established. Otherwise, these requests in hw queue might
2137 * never be dispatched.
2139 * For example, there is a single hw queue (hctx) and two CPU queues
2140 * (ctx0 for CPU0, and ctx1 for CPU1).
2142 * Now CPU1 is just onlined and a request is inserted into
2143 * ctx1->rq_list and set bit0 in pending bitmap as ctx1->index_hw is
2146 * And then while running hw queue, flush_busy_ctxs() finds bit0 is
2147 * set in pending bitmap and tries to retrieve requests in
2148 * hctx->ctxs[0]->rq_list. But htx->ctxs[0] is a pointer to ctx0,
2149 * so the request in ctx1->rq_list is ignored.
2151 switch (action
& ~CPU_TASKS_FROZEN
) {
2153 case CPU_UP_CANCELED
:
2154 cpumask_copy(&online_new
, cpu_online_mask
);
2156 case CPU_UP_PREPARE
:
2157 cpumask_copy(&online_new
, cpu_online_mask
);
2158 cpumask_set_cpu(cpu
, &online_new
);
2164 mutex_lock(&all_q_mutex
);
2167 * We need to freeze and reinit all existing queues. Freezing
2168 * involves synchronous wait for an RCU grace period and doing it
2169 * one by one may take a long time. Start freezing all queues in
2170 * one swoop and then wait for the completions so that freezing can
2171 * take place in parallel.
2173 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2174 blk_mq_freeze_queue_start(q
);
2175 list_for_each_entry(q
, &all_q_list
, all_q_node
) {
2176 blk_mq_freeze_queue_wait(q
);
2179 * timeout handler can't touch hw queue during the
2182 del_timer_sync(&q
->timeout
);
2185 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2186 blk_mq_queue_reinit(q
, &online_new
);
2188 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2189 blk_mq_unfreeze_queue(q
);
2191 mutex_unlock(&all_q_mutex
);
2195 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2199 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2200 set
->tags
[i
] = blk_mq_init_rq_map(set
, i
);
2209 blk_mq_free_rq_map(set
, set
->tags
[i
], i
);
2215 * Allocate the request maps associated with this tag_set. Note that this
2216 * may reduce the depth asked for, if memory is tight. set->queue_depth
2217 * will be updated to reflect the allocated depth.
2219 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2224 depth
= set
->queue_depth
;
2226 err
= __blk_mq_alloc_rq_maps(set
);
2230 set
->queue_depth
>>= 1;
2231 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2235 } while (set
->queue_depth
);
2237 if (!set
->queue_depth
|| err
) {
2238 pr_err("blk-mq: failed to allocate request map\n");
2242 if (depth
!= set
->queue_depth
)
2243 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2244 depth
, set
->queue_depth
);
2249 struct cpumask
*blk_mq_tags_cpumask(struct blk_mq_tags
*tags
)
2251 return tags
->cpumask
;
2253 EXPORT_SYMBOL_GPL(blk_mq_tags_cpumask
);
2256 * Alloc a tag set to be associated with one or more request queues.
2257 * May fail with EINVAL for various error conditions. May adjust the
2258 * requested depth down, if if it too large. In that case, the set
2259 * value will be stored in set->queue_depth.
2261 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2263 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2265 if (!set
->nr_hw_queues
)
2267 if (!set
->queue_depth
)
2269 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2272 if (!set
->ops
->queue_rq
|| !set
->ops
->map_queue
)
2275 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2276 pr_info("blk-mq: reduced tag depth to %u\n",
2278 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2282 * If a crashdump is active, then we are potentially in a very
2283 * memory constrained environment. Limit us to 1 queue and
2284 * 64 tags to prevent using too much memory.
2286 if (is_kdump_kernel()) {
2287 set
->nr_hw_queues
= 1;
2288 set
->queue_depth
= min(64U, set
->queue_depth
);
2291 set
->tags
= kmalloc_node(set
->nr_hw_queues
*
2292 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
< set
->nr_hw_queues
; 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
) {
2336 ret
= blk_mq_tag_update_depth(hctx
->tags
, nr
);
2342 q
->nr_requests
= nr
;
2347 void blk_mq_disable_hotplug(void)
2349 mutex_lock(&all_q_mutex
);
2352 void blk_mq_enable_hotplug(void)
2354 mutex_unlock(&all_q_mutex
);
2357 static int __init
blk_mq_init(void)
2361 hotcpu_notifier(blk_mq_queue_reinit_notify
, 0);
2365 subsys_initcall(blk_mq_init
);