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/sched/topology.h>
24 #include <linux/sched/signal.h>
25 #include <linux/delay.h>
26 #include <linux/crash_dump.h>
27 #include <linux/prefetch.h>
29 #include <trace/events/block.h>
31 #include <linux/blk-mq.h>
34 #include "blk-mq-debugfs.h"
35 #include "blk-mq-tag.h"
38 #include "blk-mq-sched.h"
40 static DEFINE_MUTEX(all_q_mutex
);
41 static LIST_HEAD(all_q_list
);
43 static void blk_mq_poll_stats_start(struct request_queue
*q
);
44 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
);
46 static int blk_mq_poll_stats_bkt(const struct request
*rq
)
48 int ddir
, bytes
, bucket
;
50 ddir
= rq_data_dir(rq
);
51 bytes
= blk_rq_bytes(rq
);
53 bucket
= ddir
+ 2*(ilog2(bytes
) - 9);
57 else if (bucket
>= BLK_MQ_POLL_STATS_BKTS
)
58 return ddir
+ BLK_MQ_POLL_STATS_BKTS
- 2;
64 * Check if any of the ctx's have pending work in this hardware queue
66 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
68 return sbitmap_any_bit_set(&hctx
->ctx_map
) ||
69 !list_empty_careful(&hctx
->dispatch
) ||
70 blk_mq_sched_has_work(hctx
);
74 * Mark this ctx as having pending work in this hardware queue
76 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
77 struct blk_mq_ctx
*ctx
)
79 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
80 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
83 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
84 struct blk_mq_ctx
*ctx
)
86 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
89 void blk_freeze_queue_start(struct request_queue
*q
)
93 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
94 if (freeze_depth
== 1) {
95 percpu_ref_kill(&q
->q_usage_counter
);
96 blk_mq_run_hw_queues(q
, false);
99 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
101 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
103 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
105 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
107 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
108 unsigned long timeout
)
110 return wait_event_timeout(q
->mq_freeze_wq
,
111 percpu_ref_is_zero(&q
->q_usage_counter
),
114 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
117 * Guarantee no request is in use, so we can change any data structure of
118 * the queue afterward.
120 void blk_freeze_queue(struct request_queue
*q
)
123 * In the !blk_mq case we are only calling this to kill the
124 * q_usage_counter, otherwise this increases the freeze depth
125 * and waits for it to return to zero. For this reason there is
126 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
127 * exported to drivers as the only user for unfreeze is blk_mq.
129 blk_freeze_queue_start(q
);
130 blk_mq_freeze_queue_wait(q
);
133 void blk_mq_freeze_queue(struct request_queue
*q
)
136 * ...just an alias to keep freeze and unfreeze actions balanced
137 * in the blk_mq_* namespace
141 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
143 void blk_mq_unfreeze_queue(struct request_queue
*q
)
147 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
148 WARN_ON_ONCE(freeze_depth
< 0);
150 percpu_ref_reinit(&q
->q_usage_counter
);
151 wake_up_all(&q
->mq_freeze_wq
);
154 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
157 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
158 * mpt3sas driver such that this function can be removed.
160 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
164 spin_lock_irqsave(q
->queue_lock
, flags
);
165 queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
166 spin_unlock_irqrestore(q
->queue_lock
, flags
);
168 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
171 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
174 * Note: this function does not prevent that the struct request end_io()
175 * callback function is invoked. Once this function is returned, we make
176 * sure no dispatch can happen until the queue is unquiesced via
177 * blk_mq_unquiesce_queue().
179 void blk_mq_quiesce_queue(struct request_queue
*q
)
181 struct blk_mq_hw_ctx
*hctx
;
185 blk_mq_quiesce_queue_nowait(q
);
187 queue_for_each_hw_ctx(q
, hctx
, i
) {
188 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
189 synchronize_srcu(hctx
->queue_rq_srcu
);
196 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
199 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
202 * This function recovers queue into the state before quiescing
203 * which is done by blk_mq_quiesce_queue.
205 void blk_mq_unquiesce_queue(struct request_queue
*q
)
209 spin_lock_irqsave(q
->queue_lock
, flags
);
210 queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
211 spin_unlock_irqrestore(q
->queue_lock
, flags
);
213 /* dispatch requests which are inserted during quiescing */
214 blk_mq_run_hw_queues(q
, true);
216 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
218 void blk_mq_wake_waiters(struct request_queue
*q
)
220 struct blk_mq_hw_ctx
*hctx
;
223 queue_for_each_hw_ctx(q
, hctx
, i
)
224 if (blk_mq_hw_queue_mapped(hctx
))
225 blk_mq_tag_wakeup_all(hctx
->tags
, true);
228 * If we are called because the queue has now been marked as
229 * dying, we need to ensure that processes currently waiting on
230 * the queue are notified as well.
232 wake_up_all(&q
->mq_freeze_wq
);
235 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
237 return blk_mq_has_free_tags(hctx
->tags
);
239 EXPORT_SYMBOL(blk_mq_can_queue
);
241 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
242 unsigned int tag
, unsigned int op
)
244 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
245 struct request
*rq
= tags
->static_rqs
[tag
];
249 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
251 rq
->internal_tag
= tag
;
253 if (blk_mq_tag_busy(data
->hctx
)) {
254 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
255 atomic_inc(&data
->hctx
->nr_active
);
258 rq
->internal_tag
= -1;
259 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
262 INIT_LIST_HEAD(&rq
->queuelist
);
263 /* csd/requeue_work/fifo_time is initialized before use */
265 rq
->mq_ctx
= data
->ctx
;
267 if (blk_queue_io_stat(data
->q
))
268 rq
->rq_flags
|= RQF_IO_STAT
;
269 /* do not touch atomic flags, it needs atomic ops against the timer */
271 INIT_HLIST_NODE(&rq
->hash
);
272 RB_CLEAR_NODE(&rq
->rb_node
);
275 rq
->start_time
= jiffies
;
276 #ifdef CONFIG_BLK_CGROUP
278 set_start_time_ns(rq
);
279 rq
->io_start_time_ns
= 0;
281 rq
->nr_phys_segments
= 0;
282 #if defined(CONFIG_BLK_DEV_INTEGRITY)
283 rq
->nr_integrity_segments
= 0;
286 /* tag was already set */
289 INIT_LIST_HEAD(&rq
->timeout_list
);
293 rq
->end_io_data
= NULL
;
296 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
300 static struct request
*blk_mq_get_request(struct request_queue
*q
,
301 struct bio
*bio
, unsigned int op
,
302 struct blk_mq_alloc_data
*data
)
304 struct elevator_queue
*e
= q
->elevator
;
308 blk_queue_enter_live(q
);
310 if (likely(!data
->ctx
))
311 data
->ctx
= blk_mq_get_ctx(q
);
312 if (likely(!data
->hctx
))
313 data
->hctx
= blk_mq_map_queue(q
, data
->ctx
->cpu
);
315 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
318 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
321 * Flush requests are special and go directly to the
324 if (!op_is_flush(op
) && e
->type
->ops
.mq
.limit_depth
)
325 e
->type
->ops
.mq
.limit_depth(op
, data
);
328 tag
= blk_mq_get_tag(data
);
329 if (tag
== BLK_MQ_TAG_FAIL
) {
334 rq
= blk_mq_rq_ctx_init(data
, tag
, op
);
335 if (!op_is_flush(op
)) {
337 if (e
&& e
->type
->ops
.mq
.prepare_request
) {
338 if (e
->type
->icq_cache
&& rq_ioc(bio
))
339 blk_mq_sched_assign_ioc(rq
, bio
);
341 e
->type
->ops
.mq
.prepare_request(rq
, bio
);
342 rq
->rq_flags
|= RQF_ELVPRIV
;
345 data
->hctx
->queued
++;
349 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
352 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
356 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
360 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
362 blk_mq_put_ctx(alloc_data
.ctx
);
366 return ERR_PTR(-EWOULDBLOCK
);
369 rq
->__sector
= (sector_t
) -1;
370 rq
->bio
= rq
->biotail
= NULL
;
373 EXPORT_SYMBOL(blk_mq_alloc_request
);
375 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
376 unsigned int op
, unsigned int flags
, unsigned int hctx_idx
)
378 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
384 * If the tag allocator sleeps we could get an allocation for a
385 * different hardware context. No need to complicate the low level
386 * allocator for this for the rare use case of a command tied to
389 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
390 return ERR_PTR(-EINVAL
);
392 if (hctx_idx
>= q
->nr_hw_queues
)
393 return ERR_PTR(-EIO
);
395 ret
= blk_queue_enter(q
, true);
400 * Check if the hardware context is actually mapped to anything.
401 * If not tell the caller that it should skip this queue.
403 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
404 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
406 return ERR_PTR(-EXDEV
);
408 cpu
= cpumask_first(alloc_data
.hctx
->cpumask
);
409 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
411 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
416 return ERR_PTR(-EWOULDBLOCK
);
420 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
422 void blk_mq_free_request(struct request
*rq
)
424 struct request_queue
*q
= rq
->q
;
425 struct elevator_queue
*e
= q
->elevator
;
426 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
427 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
428 const int sched_tag
= rq
->internal_tag
;
430 if (rq
->rq_flags
& RQF_ELVPRIV
) {
431 if (e
&& e
->type
->ops
.mq
.finish_request
)
432 e
->type
->ops
.mq
.finish_request(rq
);
434 put_io_context(rq
->elv
.icq
->ioc
);
439 ctx
->rq_completed
[rq_is_sync(rq
)]++;
440 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
441 atomic_dec(&hctx
->nr_active
);
443 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
445 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
446 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
448 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
450 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
451 blk_mq_sched_restart(hctx
);
454 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
456 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
458 blk_account_io_done(rq
);
461 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
462 rq
->end_io(rq
, error
);
464 if (unlikely(blk_bidi_rq(rq
)))
465 blk_mq_free_request(rq
->next_rq
);
466 blk_mq_free_request(rq
);
469 EXPORT_SYMBOL(__blk_mq_end_request
);
471 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
473 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
475 __blk_mq_end_request(rq
, error
);
477 EXPORT_SYMBOL(blk_mq_end_request
);
479 static void __blk_mq_complete_request_remote(void *data
)
481 struct request
*rq
= data
;
483 rq
->q
->softirq_done_fn(rq
);
486 static void __blk_mq_complete_request(struct request
*rq
)
488 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
492 if (rq
->internal_tag
!= -1)
493 blk_mq_sched_completed_request(rq
);
494 if (rq
->rq_flags
& RQF_STATS
) {
495 blk_mq_poll_stats_start(rq
->q
);
499 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
500 rq
->q
->softirq_done_fn(rq
);
505 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
506 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
508 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
509 rq
->csd
.func
= __blk_mq_complete_request_remote
;
512 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
514 rq
->q
->softirq_done_fn(rq
);
520 * blk_mq_complete_request - end I/O on a request
521 * @rq: the request being processed
524 * Ends all I/O on a request. It does not handle partial completions.
525 * The actual completion happens out-of-order, through a IPI handler.
527 void blk_mq_complete_request(struct request
*rq
)
529 struct request_queue
*q
= rq
->q
;
531 if (unlikely(blk_should_fake_timeout(q
)))
533 if (!blk_mark_rq_complete(rq
))
534 __blk_mq_complete_request(rq
);
536 EXPORT_SYMBOL(blk_mq_complete_request
);
538 int blk_mq_request_started(struct request
*rq
)
540 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
542 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
544 void blk_mq_start_request(struct request
*rq
)
546 struct request_queue
*q
= rq
->q
;
548 blk_mq_sched_started_request(rq
);
550 trace_block_rq_issue(q
, rq
);
552 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
553 blk_stat_set_issue(&rq
->issue_stat
, blk_rq_sectors(rq
));
554 rq
->rq_flags
|= RQF_STATS
;
555 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
561 * Ensure that ->deadline is visible before set the started
562 * flag and clear the completed flag.
564 smp_mb__before_atomic();
567 * Mark us as started and clear complete. Complete might have been
568 * set if requeue raced with timeout, which then marked it as
569 * complete. So be sure to clear complete again when we start
570 * the request, otherwise we'll ignore the completion event.
572 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
573 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
574 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
575 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
577 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
579 * Make sure space for the drain appears. We know we can do
580 * this because max_hw_segments has been adjusted to be one
581 * fewer than the device can handle.
583 rq
->nr_phys_segments
++;
586 EXPORT_SYMBOL(blk_mq_start_request
);
589 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
590 * flag isn't set yet, so there may be race with timeout handler,
591 * but given rq->deadline is just set in .queue_rq() under
592 * this situation, the race won't be possible in reality because
593 * rq->timeout should be set as big enough to cover the window
594 * between blk_mq_start_request() called from .queue_rq() and
595 * clearing REQ_ATOM_STARTED here.
597 static void __blk_mq_requeue_request(struct request
*rq
)
599 struct request_queue
*q
= rq
->q
;
601 trace_block_rq_requeue(q
, rq
);
602 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
603 blk_mq_sched_requeue_request(rq
);
605 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
606 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
607 rq
->nr_phys_segments
--;
611 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
613 __blk_mq_requeue_request(rq
);
615 BUG_ON(blk_queued_rq(rq
));
616 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
618 EXPORT_SYMBOL(blk_mq_requeue_request
);
620 static void blk_mq_requeue_work(struct work_struct
*work
)
622 struct request_queue
*q
=
623 container_of(work
, struct request_queue
, requeue_work
.work
);
625 struct request
*rq
, *next
;
628 spin_lock_irqsave(&q
->requeue_lock
, flags
);
629 list_splice_init(&q
->requeue_list
, &rq_list
);
630 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
632 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
633 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
636 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
637 list_del_init(&rq
->queuelist
);
638 blk_mq_sched_insert_request(rq
, true, false, false, true);
641 while (!list_empty(&rq_list
)) {
642 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
643 list_del_init(&rq
->queuelist
);
644 blk_mq_sched_insert_request(rq
, false, false, false, true);
647 blk_mq_run_hw_queues(q
, false);
650 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
651 bool kick_requeue_list
)
653 struct request_queue
*q
= rq
->q
;
657 * We abuse this flag that is otherwise used by the I/O scheduler to
658 * request head insertation from the workqueue.
660 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
662 spin_lock_irqsave(&q
->requeue_lock
, flags
);
664 rq
->rq_flags
|= RQF_SOFTBARRIER
;
665 list_add(&rq
->queuelist
, &q
->requeue_list
);
667 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
669 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
671 if (kick_requeue_list
)
672 blk_mq_kick_requeue_list(q
);
674 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
676 void blk_mq_kick_requeue_list(struct request_queue
*q
)
678 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
680 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
682 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
685 kblockd_schedule_delayed_work(&q
->requeue_work
,
686 msecs_to_jiffies(msecs
));
688 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
690 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
692 if (tag
< tags
->nr_tags
) {
693 prefetch(tags
->rqs
[tag
]);
694 return tags
->rqs
[tag
];
699 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
701 struct blk_mq_timeout_data
{
703 unsigned int next_set
;
706 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
708 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
709 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
712 * We know that complete is set at this point. If STARTED isn't set
713 * anymore, then the request isn't active and the "timeout" should
714 * just be ignored. This can happen due to the bitflag ordering.
715 * Timeout first checks if STARTED is set, and if it is, assumes
716 * the request is active. But if we race with completion, then
717 * both flags will get cleared. So check here again, and ignore
718 * a timeout event with a request that isn't active.
720 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
724 ret
= ops
->timeout(req
, reserved
);
728 __blk_mq_complete_request(req
);
730 case BLK_EH_RESET_TIMER
:
732 blk_clear_rq_complete(req
);
734 case BLK_EH_NOT_HANDLED
:
737 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
742 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
743 struct request
*rq
, void *priv
, bool reserved
)
745 struct blk_mq_timeout_data
*data
= priv
;
747 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
751 * The rq being checked may have been freed and reallocated
752 * out already here, we avoid this race by checking rq->deadline
753 * and REQ_ATOM_COMPLETE flag together:
755 * - if rq->deadline is observed as new value because of
756 * reusing, the rq won't be timed out because of timing.
757 * - if rq->deadline is observed as previous value,
758 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
759 * because we put a barrier between setting rq->deadline
760 * and clearing the flag in blk_mq_start_request(), so
761 * this rq won't be timed out too.
763 if (time_after_eq(jiffies
, rq
->deadline
)) {
764 if (!blk_mark_rq_complete(rq
))
765 blk_mq_rq_timed_out(rq
, reserved
);
766 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
767 data
->next
= rq
->deadline
;
772 static void blk_mq_timeout_work(struct work_struct
*work
)
774 struct request_queue
*q
=
775 container_of(work
, struct request_queue
, timeout_work
);
776 struct blk_mq_timeout_data data
= {
782 /* A deadlock might occur if a request is stuck requiring a
783 * timeout at the same time a queue freeze is waiting
784 * completion, since the timeout code would not be able to
785 * acquire the queue reference here.
787 * That's why we don't use blk_queue_enter here; instead, we use
788 * percpu_ref_tryget directly, because we need to be able to
789 * obtain a reference even in the short window between the queue
790 * starting to freeze, by dropping the first reference in
791 * blk_freeze_queue_start, and the moment the last request is
792 * consumed, marked by the instant q_usage_counter reaches
795 if (!percpu_ref_tryget(&q
->q_usage_counter
))
798 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
801 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
802 mod_timer(&q
->timeout
, data
.next
);
804 struct blk_mq_hw_ctx
*hctx
;
806 queue_for_each_hw_ctx(q
, hctx
, i
) {
807 /* the hctx may be unmapped, so check it here */
808 if (blk_mq_hw_queue_mapped(hctx
))
809 blk_mq_tag_idle(hctx
);
815 struct flush_busy_ctx_data
{
816 struct blk_mq_hw_ctx
*hctx
;
817 struct list_head
*list
;
820 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
822 struct flush_busy_ctx_data
*flush_data
= data
;
823 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
824 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
826 sbitmap_clear_bit(sb
, bitnr
);
827 spin_lock(&ctx
->lock
);
828 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
829 spin_unlock(&ctx
->lock
);
834 * Process software queues that have been marked busy, splicing them
835 * to the for-dispatch
837 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
839 struct flush_busy_ctx_data data
= {
844 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
846 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
848 static inline unsigned int queued_to_index(unsigned int queued
)
853 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
856 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
859 struct blk_mq_alloc_data data
= {
861 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
862 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
865 might_sleep_if(wait
);
870 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
871 data
.flags
|= BLK_MQ_REQ_RESERVED
;
873 rq
->tag
= blk_mq_get_tag(&data
);
875 if (blk_mq_tag_busy(data
.hctx
)) {
876 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
877 atomic_inc(&data
.hctx
->nr_active
);
879 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
885 return rq
->tag
!= -1;
888 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx
*hctx
,
891 blk_mq_put_tag(hctx
, hctx
->tags
, rq
->mq_ctx
, rq
->tag
);
894 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
) {
895 rq
->rq_flags
&= ~RQF_MQ_INFLIGHT
;
896 atomic_dec(&hctx
->nr_active
);
900 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx
*hctx
,
903 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
906 __blk_mq_put_driver_tag(hctx
, rq
);
909 static void blk_mq_put_driver_tag(struct request
*rq
)
911 struct blk_mq_hw_ctx
*hctx
;
913 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
916 hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
);
917 __blk_mq_put_driver_tag(hctx
, rq
);
921 * If we fail getting a driver tag because all the driver tags are already
922 * assigned and on the dispatch list, BUT the first entry does not have a
923 * tag, then we could deadlock. For that case, move entries with assigned
924 * driver tags to the front, leaving the set of tagged requests in the
925 * same order, and the untagged set in the same order.
927 static bool reorder_tags_to_front(struct list_head
*list
)
929 struct request
*rq
, *tmp
, *first
= NULL
;
931 list_for_each_entry_safe_reverse(rq
, tmp
, list
, queuelist
) {
935 list_move(&rq
->queuelist
, list
);
941 return first
!= NULL
;
944 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
, int flags
,
947 struct blk_mq_hw_ctx
*hctx
;
949 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
951 list_del(&wait
->entry
);
952 clear_bit_unlock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
);
953 blk_mq_run_hw_queue(hctx
, true);
957 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx
*hctx
)
959 struct sbq_wait_state
*ws
;
962 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
963 * The thread which wins the race to grab this bit adds the hardware
964 * queue to the wait queue.
966 if (test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
) ||
967 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
970 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
971 ws
= bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
);
974 * As soon as this returns, it's no longer safe to fiddle with
975 * hctx->dispatch_wait, since a completion can wake up the wait queue
976 * and unlock the bit.
978 add_wait_queue(&ws
->wait
, &hctx
->dispatch_wait
);
982 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
)
984 struct blk_mq_hw_ctx
*hctx
;
988 if (list_empty(list
))
992 * Now process all the entries, sending them to the driver.
996 struct blk_mq_queue_data bd
;
999 rq
= list_first_entry(list
, struct request
, queuelist
);
1000 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
1001 if (!queued
&& reorder_tags_to_front(list
))
1005 * The initial allocation attempt failed, so we need to
1006 * rerun the hardware queue when a tag is freed.
1008 if (!blk_mq_dispatch_wait_add(hctx
))
1012 * It's possible that a tag was freed in the window
1013 * between the allocation failure and adding the
1014 * hardware queue to the wait queue.
1016 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
1020 list_del_init(&rq
->queuelist
);
1025 * Flag last if we have no more requests, or if we have more
1026 * but can't assign a driver tag to it.
1028 if (list_empty(list
))
1031 struct request
*nxt
;
1033 nxt
= list_first_entry(list
, struct request
, queuelist
);
1034 bd
.last
= !blk_mq_get_driver_tag(nxt
, NULL
, false);
1037 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1038 if (ret
== BLK_STS_RESOURCE
) {
1039 blk_mq_put_driver_tag_hctx(hctx
, rq
);
1040 list_add(&rq
->queuelist
, list
);
1041 __blk_mq_requeue_request(rq
);
1045 if (unlikely(ret
!= BLK_STS_OK
)) {
1047 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1052 } while (!list_empty(list
));
1054 hctx
->dispatched
[queued_to_index(queued
)]++;
1057 * Any items that need requeuing? Stuff them into hctx->dispatch,
1058 * that is where we will continue on next queue run.
1060 if (!list_empty(list
)) {
1062 * If an I/O scheduler has been configured and we got a driver
1063 * tag for the next request already, free it again.
1065 rq
= list_first_entry(list
, struct request
, queuelist
);
1066 blk_mq_put_driver_tag(rq
);
1068 spin_lock(&hctx
->lock
);
1069 list_splice_init(list
, &hctx
->dispatch
);
1070 spin_unlock(&hctx
->lock
);
1073 * If SCHED_RESTART was set by the caller of this function and
1074 * it is no longer set that means that it was cleared by another
1075 * thread and hence that a queue rerun is needed.
1077 * If TAG_WAITING is set that means that an I/O scheduler has
1078 * been configured and another thread is waiting for a driver
1079 * tag. To guarantee fairness, do not rerun this hardware queue
1080 * but let the other thread grab the driver tag.
1082 * If no I/O scheduler has been configured it is possible that
1083 * the hardware queue got stopped and restarted before requests
1084 * were pushed back onto the dispatch list. Rerun the queue to
1085 * avoid starvation. Notes:
1086 * - blk_mq_run_hw_queue() checks whether or not a queue has
1087 * been stopped before rerunning a queue.
1088 * - Some but not all block drivers stop a queue before
1089 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1092 if (!blk_mq_sched_needs_restart(hctx
) &&
1093 !test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1094 blk_mq_run_hw_queue(hctx
, true);
1097 return (queued
+ errors
) != 0;
1100 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1104 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1105 cpu_online(hctx
->next_cpu
));
1107 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1109 blk_mq_sched_dispatch_requests(hctx
);
1114 srcu_idx
= srcu_read_lock(hctx
->queue_rq_srcu
);
1115 blk_mq_sched_dispatch_requests(hctx
);
1116 srcu_read_unlock(hctx
->queue_rq_srcu
, srcu_idx
);
1121 * It'd be great if the workqueue API had a way to pass
1122 * in a mask and had some smarts for more clever placement.
1123 * For now we just round-robin here, switching for every
1124 * BLK_MQ_CPU_WORK_BATCH queued items.
1126 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1128 if (hctx
->queue
->nr_hw_queues
== 1)
1129 return WORK_CPU_UNBOUND
;
1131 if (--hctx
->next_cpu_batch
<= 0) {
1134 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
1135 if (next_cpu
>= nr_cpu_ids
)
1136 next_cpu
= cpumask_first(hctx
->cpumask
);
1138 hctx
->next_cpu
= next_cpu
;
1139 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1142 return hctx
->next_cpu
;
1145 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1146 unsigned long msecs
)
1148 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1151 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1154 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1155 int cpu
= get_cpu();
1156 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1157 __blk_mq_run_hw_queue(hctx
);
1165 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1167 msecs_to_jiffies(msecs
));
1170 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1172 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1174 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1176 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1178 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1180 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1182 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1184 struct blk_mq_hw_ctx
*hctx
;
1187 queue_for_each_hw_ctx(q
, hctx
, i
) {
1188 if (!blk_mq_hctx_has_pending(hctx
) ||
1189 blk_mq_hctx_stopped(hctx
))
1192 blk_mq_run_hw_queue(hctx
, async
);
1195 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1198 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1199 * @q: request queue.
1201 * The caller is responsible for serializing this function against
1202 * blk_mq_{start,stop}_hw_queue().
1204 bool blk_mq_queue_stopped(struct request_queue
*q
)
1206 struct blk_mq_hw_ctx
*hctx
;
1209 queue_for_each_hw_ctx(q
, hctx
, i
)
1210 if (blk_mq_hctx_stopped(hctx
))
1215 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1218 * This function is often used for pausing .queue_rq() by driver when
1219 * there isn't enough resource or some conditions aren't satisfied, and
1220 * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
1222 * We do not guarantee that dispatch can be drained or blocked
1223 * after blk_mq_stop_hw_queue() returns. Please use
1224 * blk_mq_quiesce_queue() for that requirement.
1226 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1228 cancel_delayed_work(&hctx
->run_work
);
1230 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1232 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1235 * This function is often used for pausing .queue_rq() by driver when
1236 * there isn't enough resource or some conditions aren't satisfied, and
1237 * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
1239 * We do not guarantee that dispatch can be drained or blocked
1240 * after blk_mq_stop_hw_queues() returns. Please use
1241 * blk_mq_quiesce_queue() for that requirement.
1243 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1245 struct blk_mq_hw_ctx
*hctx
;
1248 queue_for_each_hw_ctx(q
, hctx
, i
)
1249 blk_mq_stop_hw_queue(hctx
);
1251 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1253 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1255 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1257 blk_mq_run_hw_queue(hctx
, false);
1259 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1261 void blk_mq_start_hw_queues(struct request_queue
*q
)
1263 struct blk_mq_hw_ctx
*hctx
;
1266 queue_for_each_hw_ctx(q
, hctx
, i
)
1267 blk_mq_start_hw_queue(hctx
);
1269 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1271 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1273 if (!blk_mq_hctx_stopped(hctx
))
1276 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1277 blk_mq_run_hw_queue(hctx
, async
);
1279 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1281 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1283 struct blk_mq_hw_ctx
*hctx
;
1286 queue_for_each_hw_ctx(q
, hctx
, i
)
1287 blk_mq_start_stopped_hw_queue(hctx
, async
);
1289 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1291 static void blk_mq_run_work_fn(struct work_struct
*work
)
1293 struct blk_mq_hw_ctx
*hctx
;
1295 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1298 * If we are stopped, don't run the queue. The exception is if
1299 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1300 * the STOPPED bit and run it.
1302 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)) {
1303 if (!test_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
))
1306 clear_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1307 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1310 __blk_mq_run_hw_queue(hctx
);
1314 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1316 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1320 * Stop the hw queue, then modify currently delayed work.
1321 * This should prevent us from running the queue prematurely.
1322 * Mark the queue as auto-clearing STOPPED when it runs.
1324 blk_mq_stop_hw_queue(hctx
);
1325 set_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1326 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1328 msecs_to_jiffies(msecs
));
1330 EXPORT_SYMBOL(blk_mq_delay_queue
);
1332 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1336 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1338 lockdep_assert_held(&ctx
->lock
);
1340 trace_block_rq_insert(hctx
->queue
, rq
);
1343 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1345 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1348 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1351 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1353 lockdep_assert_held(&ctx
->lock
);
1355 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1356 blk_mq_hctx_mark_pending(hctx
, ctx
);
1359 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1360 struct list_head
*list
)
1364 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1367 spin_lock(&ctx
->lock
);
1368 while (!list_empty(list
)) {
1371 rq
= list_first_entry(list
, struct request
, queuelist
);
1372 BUG_ON(rq
->mq_ctx
!= ctx
);
1373 list_del_init(&rq
->queuelist
);
1374 __blk_mq_insert_req_list(hctx
, rq
, false);
1376 blk_mq_hctx_mark_pending(hctx
, ctx
);
1377 spin_unlock(&ctx
->lock
);
1380 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1382 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1383 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1385 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1386 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1387 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1390 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1392 struct blk_mq_ctx
*this_ctx
;
1393 struct request_queue
*this_q
;
1396 LIST_HEAD(ctx_list
);
1399 list_splice_init(&plug
->mq_list
, &list
);
1401 list_sort(NULL
, &list
, plug_ctx_cmp
);
1407 while (!list_empty(&list
)) {
1408 rq
= list_entry_rq(list
.next
);
1409 list_del_init(&rq
->queuelist
);
1411 if (rq
->mq_ctx
!= this_ctx
) {
1413 trace_block_unplug(this_q
, depth
, from_schedule
);
1414 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1419 this_ctx
= rq
->mq_ctx
;
1425 list_add_tail(&rq
->queuelist
, &ctx_list
);
1429 * If 'this_ctx' is set, we know we have entries to complete
1430 * on 'ctx_list'. Do those.
1433 trace_block_unplug(this_q
, depth
, from_schedule
);
1434 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1439 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1441 blk_init_request_from_bio(rq
, bio
);
1443 blk_account_io_start(rq
, true);
1446 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1448 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1449 !blk_queue_nomerges(hctx
->queue
);
1452 static inline void blk_mq_queue_io(struct blk_mq_hw_ctx
*hctx
,
1453 struct blk_mq_ctx
*ctx
,
1456 spin_lock(&ctx
->lock
);
1457 __blk_mq_insert_request(hctx
, rq
, false);
1458 spin_unlock(&ctx
->lock
);
1461 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1464 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1466 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1469 static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1471 blk_qc_t
*cookie
, bool may_sleep
)
1473 struct request_queue
*q
= rq
->q
;
1474 struct blk_mq_queue_data bd
= {
1478 blk_qc_t new_cookie
;
1480 bool run_queue
= true;
1482 /* RCU or SRCU read lock is needed before checking quiesced flag */
1483 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1491 if (!blk_mq_get_driver_tag(rq
, NULL
, false))
1494 new_cookie
= request_to_qc_t(hctx
, rq
);
1497 * For OK queue, we are done. For error, kill it. Any other
1498 * error (busy), just add it to our list as we previously
1501 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1504 *cookie
= new_cookie
;
1506 case BLK_STS_RESOURCE
:
1507 __blk_mq_requeue_request(rq
);
1510 *cookie
= BLK_QC_T_NONE
;
1511 blk_mq_end_request(rq
, ret
);
1516 blk_mq_sched_insert_request(rq
, false, run_queue
, false, may_sleep
);
1519 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1520 struct request
*rq
, blk_qc_t
*cookie
)
1522 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1524 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false);
1527 unsigned int srcu_idx
;
1531 srcu_idx
= srcu_read_lock(hctx
->queue_rq_srcu
);
1532 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, true);
1533 srcu_read_unlock(hctx
->queue_rq_srcu
, srcu_idx
);
1537 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1539 const int is_sync
= op_is_sync(bio
->bi_opf
);
1540 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1541 struct blk_mq_alloc_data data
= { .flags
= 0 };
1543 unsigned int request_count
= 0;
1544 struct blk_plug
*plug
;
1545 struct request
*same_queue_rq
= NULL
;
1547 unsigned int wb_acct
;
1549 blk_queue_bounce(q
, &bio
);
1551 blk_queue_split(q
, &bio
);
1553 if (!bio_integrity_prep(bio
))
1554 return BLK_QC_T_NONE
;
1556 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1557 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1558 return BLK_QC_T_NONE
;
1560 if (blk_mq_sched_bio_merge(q
, bio
))
1561 return BLK_QC_T_NONE
;
1563 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1565 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1567 rq
= blk_mq_get_request(q
, bio
, bio
->bi_opf
, &data
);
1568 if (unlikely(!rq
)) {
1569 __wbt_done(q
->rq_wb
, wb_acct
);
1570 if (bio
->bi_opf
& REQ_NOWAIT
)
1571 bio_wouldblock_error(bio
);
1572 return BLK_QC_T_NONE
;
1575 wbt_track(&rq
->issue_stat
, wb_acct
);
1577 cookie
= request_to_qc_t(data
.hctx
, rq
);
1579 plug
= current
->plug
;
1580 if (unlikely(is_flush_fua
)) {
1581 blk_mq_put_ctx(data
.ctx
);
1582 blk_mq_bio_to_request(rq
, bio
);
1584 blk_mq_sched_insert_request(rq
, false, true, true,
1587 blk_insert_flush(rq
);
1588 blk_mq_run_hw_queue(data
.hctx
, true);
1590 } else if (plug
&& q
->nr_hw_queues
== 1) {
1591 struct request
*last
= NULL
;
1593 blk_mq_put_ctx(data
.ctx
);
1594 blk_mq_bio_to_request(rq
, bio
);
1597 * @request_count may become stale because of schedule
1598 * out, so check the list again.
1600 if (list_empty(&plug
->mq_list
))
1602 else if (blk_queue_nomerges(q
))
1603 request_count
= blk_plug_queued_count(q
);
1606 trace_block_plug(q
);
1608 last
= list_entry_rq(plug
->mq_list
.prev
);
1610 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1611 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1612 blk_flush_plug_list(plug
, false);
1613 trace_block_plug(q
);
1616 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1617 } else if (plug
&& !blk_queue_nomerges(q
)) {
1618 blk_mq_bio_to_request(rq
, bio
);
1621 * We do limited plugging. If the bio can be merged, do that.
1622 * Otherwise the existing request in the plug list will be
1623 * issued. So the plug list will have one request at most
1624 * The plug list might get flushed before this. If that happens,
1625 * the plug list is empty, and same_queue_rq is invalid.
1627 if (list_empty(&plug
->mq_list
))
1628 same_queue_rq
= NULL
;
1630 list_del_init(&same_queue_rq
->queuelist
);
1631 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1633 blk_mq_put_ctx(data
.ctx
);
1635 if (same_queue_rq
) {
1636 data
.hctx
= blk_mq_map_queue(q
,
1637 same_queue_rq
->mq_ctx
->cpu
);
1638 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
1641 } else if (q
->nr_hw_queues
> 1 && is_sync
) {
1642 blk_mq_put_ctx(data
.ctx
);
1643 blk_mq_bio_to_request(rq
, bio
);
1644 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
1645 } else if (q
->elevator
) {
1646 blk_mq_put_ctx(data
.ctx
);
1647 blk_mq_bio_to_request(rq
, bio
);
1648 blk_mq_sched_insert_request(rq
, false, true, true, true);
1650 blk_mq_put_ctx(data
.ctx
);
1651 blk_mq_bio_to_request(rq
, bio
);
1652 blk_mq_queue_io(data
.hctx
, data
.ctx
, rq
);
1653 blk_mq_run_hw_queue(data
.hctx
, true);
1659 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1660 unsigned int hctx_idx
)
1664 if (tags
->rqs
&& set
->ops
->exit_request
) {
1667 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1668 struct request
*rq
= tags
->static_rqs
[i
];
1672 set
->ops
->exit_request(set
, rq
, hctx_idx
);
1673 tags
->static_rqs
[i
] = NULL
;
1677 while (!list_empty(&tags
->page_list
)) {
1678 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1679 list_del_init(&page
->lru
);
1681 * Remove kmemleak object previously allocated in
1682 * blk_mq_init_rq_map().
1684 kmemleak_free(page_address(page
));
1685 __free_pages(page
, page
->private);
1689 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1693 kfree(tags
->static_rqs
);
1694 tags
->static_rqs
= NULL
;
1696 blk_mq_free_tags(tags
);
1699 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1700 unsigned int hctx_idx
,
1701 unsigned int nr_tags
,
1702 unsigned int reserved_tags
)
1704 struct blk_mq_tags
*tags
;
1707 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1708 if (node
== NUMA_NO_NODE
)
1709 node
= set
->numa_node
;
1711 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
1712 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1716 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1717 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1720 blk_mq_free_tags(tags
);
1724 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1725 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1727 if (!tags
->static_rqs
) {
1729 blk_mq_free_tags(tags
);
1736 static size_t order_to_size(unsigned int order
)
1738 return (size_t)PAGE_SIZE
<< order
;
1741 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1742 unsigned int hctx_idx
, unsigned int depth
)
1744 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1745 size_t rq_size
, left
;
1748 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1749 if (node
== NUMA_NO_NODE
)
1750 node
= set
->numa_node
;
1752 INIT_LIST_HEAD(&tags
->page_list
);
1755 * rq_size is the size of the request plus driver payload, rounded
1756 * to the cacheline size
1758 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1760 left
= rq_size
* depth
;
1762 for (i
= 0; i
< depth
; ) {
1763 int this_order
= max_order
;
1768 while (this_order
&& left
< order_to_size(this_order
- 1))
1772 page
= alloc_pages_node(node
,
1773 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1779 if (order_to_size(this_order
) < rq_size
)
1786 page
->private = this_order
;
1787 list_add_tail(&page
->lru
, &tags
->page_list
);
1789 p
= page_address(page
);
1791 * Allow kmemleak to scan these pages as they contain pointers
1792 * to additional allocations like via ops->init_request().
1794 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1795 entries_per_page
= order_to_size(this_order
) / rq_size
;
1796 to_do
= min(entries_per_page
, depth
- i
);
1797 left
-= to_do
* rq_size
;
1798 for (j
= 0; j
< to_do
; j
++) {
1799 struct request
*rq
= p
;
1801 tags
->static_rqs
[i
] = rq
;
1802 if (set
->ops
->init_request
) {
1803 if (set
->ops
->init_request(set
, rq
, hctx_idx
,
1805 tags
->static_rqs
[i
] = NULL
;
1817 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1822 * 'cpu' is going away. splice any existing rq_list entries from this
1823 * software queue to the hw queue dispatch list, and ensure that it
1826 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1828 struct blk_mq_hw_ctx
*hctx
;
1829 struct blk_mq_ctx
*ctx
;
1832 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1833 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1835 spin_lock(&ctx
->lock
);
1836 if (!list_empty(&ctx
->rq_list
)) {
1837 list_splice_init(&ctx
->rq_list
, &tmp
);
1838 blk_mq_hctx_clear_pending(hctx
, ctx
);
1840 spin_unlock(&ctx
->lock
);
1842 if (list_empty(&tmp
))
1845 spin_lock(&hctx
->lock
);
1846 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1847 spin_unlock(&hctx
->lock
);
1849 blk_mq_run_hw_queue(hctx
, true);
1853 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
1855 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
1859 /* hctx->ctxs will be freed in queue's release handler */
1860 static void blk_mq_exit_hctx(struct request_queue
*q
,
1861 struct blk_mq_tag_set
*set
,
1862 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1864 blk_mq_debugfs_unregister_hctx(hctx
);
1866 blk_mq_tag_idle(hctx
);
1868 if (set
->ops
->exit_request
)
1869 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
1871 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
1873 if (set
->ops
->exit_hctx
)
1874 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1876 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1877 cleanup_srcu_struct(hctx
->queue_rq_srcu
);
1879 blk_mq_remove_cpuhp(hctx
);
1880 blk_free_flush_queue(hctx
->fq
);
1881 sbitmap_free(&hctx
->ctx_map
);
1884 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1885 struct blk_mq_tag_set
*set
, int nr_queue
)
1887 struct blk_mq_hw_ctx
*hctx
;
1890 queue_for_each_hw_ctx(q
, hctx
, i
) {
1893 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1897 static int blk_mq_init_hctx(struct request_queue
*q
,
1898 struct blk_mq_tag_set
*set
,
1899 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1903 node
= hctx
->numa_node
;
1904 if (node
== NUMA_NO_NODE
)
1905 node
= hctx
->numa_node
= set
->numa_node
;
1907 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1908 spin_lock_init(&hctx
->lock
);
1909 INIT_LIST_HEAD(&hctx
->dispatch
);
1911 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1913 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
1915 hctx
->tags
= set
->tags
[hctx_idx
];
1918 * Allocate space for all possible cpus to avoid allocation at
1921 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1924 goto unregister_cpu_notifier
;
1926 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
1932 if (set
->ops
->init_hctx
&&
1933 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1936 if (blk_mq_sched_init_hctx(q
, hctx
, hctx_idx
))
1939 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
1941 goto sched_exit_hctx
;
1943 if (set
->ops
->init_request
&&
1944 set
->ops
->init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
1948 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1949 init_srcu_struct(hctx
->queue_rq_srcu
);
1951 blk_mq_debugfs_register_hctx(q
, hctx
);
1958 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
1960 if (set
->ops
->exit_hctx
)
1961 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1963 sbitmap_free(&hctx
->ctx_map
);
1966 unregister_cpu_notifier
:
1967 blk_mq_remove_cpuhp(hctx
);
1971 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
1972 unsigned int nr_hw_queues
)
1976 for_each_possible_cpu(i
) {
1977 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
1978 struct blk_mq_hw_ctx
*hctx
;
1981 spin_lock_init(&__ctx
->lock
);
1982 INIT_LIST_HEAD(&__ctx
->rq_list
);
1985 /* If the cpu isn't online, the cpu is mapped to first hctx */
1989 hctx
= blk_mq_map_queue(q
, i
);
1992 * Set local node, IFF we have more than one hw queue. If
1993 * not, we remain on the home node of the device
1995 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
1996 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2000 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2004 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2005 set
->queue_depth
, set
->reserved_tags
);
2006 if (!set
->tags
[hctx_idx
])
2009 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2014 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2015 set
->tags
[hctx_idx
] = NULL
;
2019 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2020 unsigned int hctx_idx
)
2022 if (set
->tags
[hctx_idx
]) {
2023 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2024 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2025 set
->tags
[hctx_idx
] = NULL
;
2029 static void blk_mq_map_swqueue(struct request_queue
*q
,
2030 const struct cpumask
*online_mask
)
2032 unsigned int i
, hctx_idx
;
2033 struct blk_mq_hw_ctx
*hctx
;
2034 struct blk_mq_ctx
*ctx
;
2035 struct blk_mq_tag_set
*set
= q
->tag_set
;
2038 * Avoid others reading imcomplete hctx->cpumask through sysfs
2040 mutex_lock(&q
->sysfs_lock
);
2042 queue_for_each_hw_ctx(q
, hctx
, i
) {
2043 cpumask_clear(hctx
->cpumask
);
2048 * Map software to hardware queues
2050 for_each_possible_cpu(i
) {
2051 /* If the cpu isn't online, the cpu is mapped to first hctx */
2052 if (!cpumask_test_cpu(i
, online_mask
))
2055 hctx_idx
= q
->mq_map
[i
];
2056 /* unmapped hw queue can be remapped after CPU topo changed */
2057 if (!set
->tags
[hctx_idx
] &&
2058 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2060 * If tags initialization fail for some hctx,
2061 * that hctx won't be brought online. In this
2062 * case, remap the current ctx to hctx[0] which
2063 * is guaranteed to always have tags allocated
2068 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2069 hctx
= blk_mq_map_queue(q
, i
);
2071 cpumask_set_cpu(i
, hctx
->cpumask
);
2072 ctx
->index_hw
= hctx
->nr_ctx
;
2073 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2076 mutex_unlock(&q
->sysfs_lock
);
2078 queue_for_each_hw_ctx(q
, hctx
, i
) {
2080 * If no software queues are mapped to this hardware queue,
2081 * disable it and free the request entries.
2083 if (!hctx
->nr_ctx
) {
2084 /* Never unmap queue 0. We need it as a
2085 * fallback in case of a new remap fails
2088 if (i
&& set
->tags
[i
])
2089 blk_mq_free_map_and_requests(set
, i
);
2095 hctx
->tags
= set
->tags
[i
];
2096 WARN_ON(!hctx
->tags
);
2099 * Set the map size to the number of mapped software queues.
2100 * This is more accurate and more efficient than looping
2101 * over all possibly mapped software queues.
2103 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2106 * Initialize batch roundrobin counts
2108 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2109 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2114 * Caller needs to ensure that we're either frozen/quiesced, or that
2115 * the queue isn't live yet.
2117 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2119 struct blk_mq_hw_ctx
*hctx
;
2122 queue_for_each_hw_ctx(q
, hctx
, i
) {
2124 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2125 atomic_inc(&q
->shared_hctx_restart
);
2126 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2128 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2129 atomic_dec(&q
->shared_hctx_restart
);
2130 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2135 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2138 struct request_queue
*q
;
2140 lockdep_assert_held(&set
->tag_list_lock
);
2142 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2143 blk_mq_freeze_queue(q
);
2144 queue_set_hctx_shared(q
, shared
);
2145 blk_mq_unfreeze_queue(q
);
2149 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2151 struct blk_mq_tag_set
*set
= q
->tag_set
;
2153 mutex_lock(&set
->tag_list_lock
);
2154 list_del_rcu(&q
->tag_set_list
);
2155 INIT_LIST_HEAD(&q
->tag_set_list
);
2156 if (list_is_singular(&set
->tag_list
)) {
2157 /* just transitioned to unshared */
2158 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2159 /* update existing queue */
2160 blk_mq_update_tag_set_depth(set
, false);
2162 mutex_unlock(&set
->tag_list_lock
);
2167 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2168 struct request_queue
*q
)
2172 mutex_lock(&set
->tag_list_lock
);
2174 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2175 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2176 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2177 /* update existing queue */
2178 blk_mq_update_tag_set_depth(set
, true);
2180 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2181 queue_set_hctx_shared(q
, true);
2182 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2184 mutex_unlock(&set
->tag_list_lock
);
2188 * It is the actual release handler for mq, but we do it from
2189 * request queue's release handler for avoiding use-after-free
2190 * and headache because q->mq_kobj shouldn't have been introduced,
2191 * but we can't group ctx/kctx kobj without it.
2193 void blk_mq_release(struct request_queue
*q
)
2195 struct blk_mq_hw_ctx
*hctx
;
2198 /* hctx kobj stays in hctx */
2199 queue_for_each_hw_ctx(q
, hctx
, i
) {
2202 kobject_put(&hctx
->kobj
);
2207 kfree(q
->queue_hw_ctx
);
2210 * release .mq_kobj and sw queue's kobject now because
2211 * both share lifetime with request queue.
2213 blk_mq_sysfs_deinit(q
);
2215 free_percpu(q
->queue_ctx
);
2218 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2220 struct request_queue
*uninit_q
, *q
;
2222 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2224 return ERR_PTR(-ENOMEM
);
2226 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2228 blk_cleanup_queue(uninit_q
);
2232 EXPORT_SYMBOL(blk_mq_init_queue
);
2234 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2236 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2238 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, queue_rq_srcu
),
2239 __alignof__(struct blk_mq_hw_ctx
)) !=
2240 sizeof(struct blk_mq_hw_ctx
));
2242 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2243 hw_ctx_size
+= sizeof(struct srcu_struct
);
2248 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2249 struct request_queue
*q
)
2252 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2254 blk_mq_sysfs_unregister(q
);
2255 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2261 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2262 hctxs
[i
] = kzalloc_node(blk_mq_hw_ctx_size(set
),
2267 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2274 atomic_set(&hctxs
[i
]->nr_active
, 0);
2275 hctxs
[i
]->numa_node
= node
;
2276 hctxs
[i
]->queue_num
= i
;
2278 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2279 free_cpumask_var(hctxs
[i
]->cpumask
);
2284 blk_mq_hctx_kobj_init(hctxs
[i
]);
2286 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2287 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2291 blk_mq_free_map_and_requests(set
, j
);
2292 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2293 kobject_put(&hctx
->kobj
);
2298 q
->nr_hw_queues
= i
;
2299 blk_mq_sysfs_register(q
);
2302 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2303 struct request_queue
*q
)
2305 /* mark the queue as mq asap */
2306 q
->mq_ops
= set
->ops
;
2308 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2309 blk_mq_poll_stats_bkt
,
2310 BLK_MQ_POLL_STATS_BKTS
, q
);
2314 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2318 /* init q->mq_kobj and sw queues' kobjects */
2319 blk_mq_sysfs_init(q
);
2321 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2322 GFP_KERNEL
, set
->numa_node
);
2323 if (!q
->queue_hw_ctx
)
2326 q
->mq_map
= set
->mq_map
;
2328 blk_mq_realloc_hw_ctxs(set
, q
);
2329 if (!q
->nr_hw_queues
)
2332 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2333 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2335 q
->nr_queues
= nr_cpu_ids
;
2337 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2339 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2340 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2342 q
->sg_reserved_size
= INT_MAX
;
2344 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2345 INIT_LIST_HEAD(&q
->requeue_list
);
2346 spin_lock_init(&q
->requeue_lock
);
2348 blk_queue_make_request(q
, blk_mq_make_request
);
2351 * Do this after blk_queue_make_request() overrides it...
2353 q
->nr_requests
= set
->queue_depth
;
2356 * Default to classic polling
2360 if (set
->ops
->complete
)
2361 blk_queue_softirq_done(q
, set
->ops
->complete
);
2363 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2366 mutex_lock(&all_q_mutex
);
2368 list_add_tail(&q
->all_q_node
, &all_q_list
);
2369 blk_mq_add_queue_tag_set(set
, q
);
2370 blk_mq_map_swqueue(q
, cpu_online_mask
);
2372 mutex_unlock(&all_q_mutex
);
2375 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2378 ret
= blk_mq_sched_init(q
);
2380 return ERR_PTR(ret
);
2386 kfree(q
->queue_hw_ctx
);
2388 free_percpu(q
->queue_ctx
);
2391 return ERR_PTR(-ENOMEM
);
2393 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2395 void blk_mq_free_queue(struct request_queue
*q
)
2397 struct blk_mq_tag_set
*set
= q
->tag_set
;
2399 mutex_lock(&all_q_mutex
);
2400 list_del_init(&q
->all_q_node
);
2401 mutex_unlock(&all_q_mutex
);
2403 blk_mq_del_queue_tag_set(q
);
2405 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2408 /* Basically redo blk_mq_init_queue with queue frozen */
2409 static void blk_mq_queue_reinit(struct request_queue
*q
,
2410 const struct cpumask
*online_mask
)
2412 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2414 blk_mq_debugfs_unregister_hctxs(q
);
2415 blk_mq_sysfs_unregister(q
);
2418 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2419 * we should change hctx numa_node according to new topology (this
2420 * involves free and re-allocate memory, worthy doing?)
2423 blk_mq_map_swqueue(q
, online_mask
);
2425 blk_mq_sysfs_register(q
);
2426 blk_mq_debugfs_register_hctxs(q
);
2430 * New online cpumask which is going to be set in this hotplug event.
2431 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2432 * one-by-one and dynamically allocating this could result in a failure.
2434 static struct cpumask cpuhp_online_new
;
2436 static void blk_mq_queue_reinit_work(void)
2438 struct request_queue
*q
;
2440 mutex_lock(&all_q_mutex
);
2442 * We need to freeze and reinit all existing queues. Freezing
2443 * involves synchronous wait for an RCU grace period and doing it
2444 * one by one may take a long time. Start freezing all queues in
2445 * one swoop and then wait for the completions so that freezing can
2446 * take place in parallel.
2448 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2449 blk_freeze_queue_start(q
);
2450 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2451 blk_mq_freeze_queue_wait(q
);
2453 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2454 blk_mq_queue_reinit(q
, &cpuhp_online_new
);
2456 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2457 blk_mq_unfreeze_queue(q
);
2459 mutex_unlock(&all_q_mutex
);
2462 static int blk_mq_queue_reinit_dead(unsigned int cpu
)
2464 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2465 blk_mq_queue_reinit_work();
2470 * Before hotadded cpu starts handling requests, new mappings must be
2471 * established. Otherwise, these requests in hw queue might never be
2474 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2475 * for CPU0, and ctx1 for CPU1).
2477 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2478 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2480 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2481 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2482 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2485 static int blk_mq_queue_reinit_prepare(unsigned int cpu
)
2487 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2488 cpumask_set_cpu(cpu
, &cpuhp_online_new
);
2489 blk_mq_queue_reinit_work();
2493 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2497 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2498 if (!__blk_mq_alloc_rq_map(set
, i
))
2505 blk_mq_free_rq_map(set
->tags
[i
]);
2511 * Allocate the request maps associated with this tag_set. Note that this
2512 * may reduce the depth asked for, if memory is tight. set->queue_depth
2513 * will be updated to reflect the allocated depth.
2515 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2520 depth
= set
->queue_depth
;
2522 err
= __blk_mq_alloc_rq_maps(set
);
2526 set
->queue_depth
>>= 1;
2527 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2531 } while (set
->queue_depth
);
2533 if (!set
->queue_depth
|| err
) {
2534 pr_err("blk-mq: failed to allocate request map\n");
2538 if (depth
!= set
->queue_depth
)
2539 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2540 depth
, set
->queue_depth
);
2545 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2547 if (set
->ops
->map_queues
)
2548 return set
->ops
->map_queues(set
);
2550 return blk_mq_map_queues(set
);
2554 * Alloc a tag set to be associated with one or more request queues.
2555 * May fail with EINVAL for various error conditions. May adjust the
2556 * requested depth down, if if it too large. In that case, the set
2557 * value will be stored in set->queue_depth.
2559 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2563 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2565 if (!set
->nr_hw_queues
)
2567 if (!set
->queue_depth
)
2569 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2572 if (!set
->ops
->queue_rq
)
2575 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2576 pr_info("blk-mq: reduced tag depth to %u\n",
2578 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2582 * If a crashdump is active, then we are potentially in a very
2583 * memory constrained environment. Limit us to 1 queue and
2584 * 64 tags to prevent using too much memory.
2586 if (is_kdump_kernel()) {
2587 set
->nr_hw_queues
= 1;
2588 set
->queue_depth
= min(64U, set
->queue_depth
);
2591 * There is no use for more h/w queues than cpus.
2593 if (set
->nr_hw_queues
> nr_cpu_ids
)
2594 set
->nr_hw_queues
= nr_cpu_ids
;
2596 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2597 GFP_KERNEL
, set
->numa_node
);
2602 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2603 GFP_KERNEL
, set
->numa_node
);
2607 ret
= blk_mq_update_queue_map(set
);
2609 goto out_free_mq_map
;
2611 ret
= blk_mq_alloc_rq_maps(set
);
2613 goto out_free_mq_map
;
2615 mutex_init(&set
->tag_list_lock
);
2616 INIT_LIST_HEAD(&set
->tag_list
);
2628 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2630 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2634 for (i
= 0; i
< nr_cpu_ids
; i
++)
2635 blk_mq_free_map_and_requests(set
, i
);
2643 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2645 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2647 struct blk_mq_tag_set
*set
= q
->tag_set
;
2648 struct blk_mq_hw_ctx
*hctx
;
2654 blk_mq_freeze_queue(q
);
2657 queue_for_each_hw_ctx(q
, hctx
, i
) {
2661 * If we're using an MQ scheduler, just update the scheduler
2662 * queue depth. This is similar to what the old code would do.
2664 if (!hctx
->sched_tags
) {
2665 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
,
2666 min(nr
, set
->queue_depth
),
2669 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2677 q
->nr_requests
= nr
;
2679 blk_mq_unfreeze_queue(q
);
2684 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
2687 struct request_queue
*q
;
2689 lockdep_assert_held(&set
->tag_list_lock
);
2691 if (nr_hw_queues
> nr_cpu_ids
)
2692 nr_hw_queues
= nr_cpu_ids
;
2693 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2696 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2697 blk_mq_freeze_queue(q
);
2699 set
->nr_hw_queues
= nr_hw_queues
;
2700 blk_mq_update_queue_map(set
);
2701 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2702 blk_mq_realloc_hw_ctxs(set
, q
);
2703 blk_mq_queue_reinit(q
, cpu_online_mask
);
2706 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2707 blk_mq_unfreeze_queue(q
);
2710 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2712 mutex_lock(&set
->tag_list_lock
);
2713 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
2714 mutex_unlock(&set
->tag_list_lock
);
2716 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2718 /* Enable polling stats and return whether they were already enabled. */
2719 static bool blk_poll_stats_enable(struct request_queue
*q
)
2721 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2722 test_and_set_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
))
2724 blk_stat_add_callback(q
, q
->poll_cb
);
2728 static void blk_mq_poll_stats_start(struct request_queue
*q
)
2731 * We don't arm the callback if polling stats are not enabled or the
2732 * callback is already active.
2734 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2735 blk_stat_is_active(q
->poll_cb
))
2738 blk_stat_activate_msecs(q
->poll_cb
, 100);
2741 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
2743 struct request_queue
*q
= cb
->data
;
2746 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
2747 if (cb
->stat
[bucket
].nr_samples
)
2748 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
2752 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2753 struct blk_mq_hw_ctx
*hctx
,
2756 unsigned long ret
= 0;
2760 * If stats collection isn't on, don't sleep but turn it on for
2763 if (!blk_poll_stats_enable(q
))
2767 * As an optimistic guess, use half of the mean service time
2768 * for this type of request. We can (and should) make this smarter.
2769 * For instance, if the completion latencies are tight, we can
2770 * get closer than just half the mean. This is especially
2771 * important on devices where the completion latencies are longer
2772 * than ~10 usec. We do use the stats for the relevant IO size
2773 * if available which does lead to better estimates.
2775 bucket
= blk_mq_poll_stats_bkt(rq
);
2779 if (q
->poll_stat
[bucket
].nr_samples
)
2780 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
2785 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2786 struct blk_mq_hw_ctx
*hctx
,
2789 struct hrtimer_sleeper hs
;
2790 enum hrtimer_mode mode
;
2794 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2800 * -1: don't ever hybrid sleep
2801 * 0: use half of prev avg
2802 * >0: use this specific value
2804 if (q
->poll_nsec
== -1)
2806 else if (q
->poll_nsec
> 0)
2807 nsecs
= q
->poll_nsec
;
2809 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2814 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2817 * This will be replaced with the stats tracking code, using
2818 * 'avg_completion_time / 2' as the pre-sleep target.
2822 mode
= HRTIMER_MODE_REL
;
2823 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2824 hrtimer_set_expires(&hs
.timer
, kt
);
2826 hrtimer_init_sleeper(&hs
, current
);
2828 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2830 set_current_state(TASK_UNINTERRUPTIBLE
);
2831 hrtimer_start_expires(&hs
.timer
, mode
);
2834 hrtimer_cancel(&hs
.timer
);
2835 mode
= HRTIMER_MODE_ABS
;
2836 } while (hs
.task
&& !signal_pending(current
));
2838 __set_current_state(TASK_RUNNING
);
2839 destroy_hrtimer_on_stack(&hs
.timer
);
2843 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2845 struct request_queue
*q
= hctx
->queue
;
2849 * If we sleep, have the caller restart the poll loop to reset
2850 * the state. Like for the other success return cases, the
2851 * caller is responsible for checking if the IO completed. If
2852 * the IO isn't complete, we'll get called again and will go
2853 * straight to the busy poll loop.
2855 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2858 hctx
->poll_considered
++;
2860 state
= current
->state
;
2861 while (!need_resched()) {
2864 hctx
->poll_invoked
++;
2866 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2868 hctx
->poll_success
++;
2869 set_current_state(TASK_RUNNING
);
2873 if (signal_pending_state(state
, current
))
2874 set_current_state(TASK_RUNNING
);
2876 if (current
->state
== TASK_RUNNING
)
2886 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2888 struct blk_mq_hw_ctx
*hctx
;
2889 struct blk_plug
*plug
;
2892 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
2893 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2896 plug
= current
->plug
;
2898 blk_flush_plug_list(plug
, false);
2900 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2901 if (!blk_qc_t_is_internal(cookie
))
2902 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2904 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2906 * With scheduling, if the request has completed, we'll
2907 * get a NULL return here, as we clear the sched tag when
2908 * that happens. The request still remains valid, like always,
2909 * so we should be safe with just the NULL check.
2915 return __blk_mq_poll(hctx
, rq
);
2917 EXPORT_SYMBOL_GPL(blk_mq_poll
);
2919 void blk_mq_disable_hotplug(void)
2921 mutex_lock(&all_q_mutex
);
2924 void blk_mq_enable_hotplug(void)
2926 mutex_unlock(&all_q_mutex
);
2929 static int __init
blk_mq_init(void)
2931 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
2932 blk_mq_hctx_notify_dead
);
2934 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE
, "block/mq:prepare",
2935 blk_mq_queue_reinit_prepare
,
2936 blk_mq_queue_reinit_dead
);
2939 subsys_initcall(blk_mq_init
);