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 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
);
41 static void blk_mq_poll_stats_start(struct request_queue
*q
);
42 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
);
44 static int blk_mq_poll_stats_bkt(const struct request
*rq
)
46 int ddir
, bytes
, bucket
;
48 ddir
= rq_data_dir(rq
);
49 bytes
= blk_rq_bytes(rq
);
51 bucket
= ddir
+ 2*(ilog2(bytes
) - 9);
55 else if (bucket
>= BLK_MQ_POLL_STATS_BKTS
)
56 return ddir
+ BLK_MQ_POLL_STATS_BKTS
- 2;
62 * Check if any of the ctx's have pending work in this hardware queue
64 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
66 return !list_empty_careful(&hctx
->dispatch
) ||
67 sbitmap_any_bit_set(&hctx
->ctx_map
) ||
68 blk_mq_sched_has_work(hctx
);
72 * Mark this ctx as having pending work in this hardware queue
74 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
75 struct blk_mq_ctx
*ctx
)
77 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
78 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
81 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
82 struct blk_mq_ctx
*ctx
)
84 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
88 struct hd_struct
*part
;
89 unsigned int *inflight
;
92 static void blk_mq_check_inflight(struct blk_mq_hw_ctx
*hctx
,
93 struct request
*rq
, void *priv
,
96 struct mq_inflight
*mi
= priv
;
98 if (test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
) &&
99 !test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
)) {
101 * index[0] counts the specific partition that was asked
102 * for. index[1] counts the ones that are active on the
103 * whole device, so increment that if mi->part is indeed
104 * a partition, and not a whole device.
106 if (rq
->part
== mi
->part
)
108 if (mi
->part
->partno
)
113 void blk_mq_in_flight(struct request_queue
*q
, struct hd_struct
*part
,
114 unsigned int inflight
[2])
116 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
118 inflight
[0] = inflight
[1] = 0;
119 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
122 void blk_freeze_queue_start(struct request_queue
*q
)
126 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
127 if (freeze_depth
== 1) {
128 percpu_ref_kill(&q
->q_usage_counter
);
130 blk_mq_run_hw_queues(q
, false);
133 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
135 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
137 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
139 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
141 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
142 unsigned long timeout
)
144 return wait_event_timeout(q
->mq_freeze_wq
,
145 percpu_ref_is_zero(&q
->q_usage_counter
),
148 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
151 * Guarantee no request is in use, so we can change any data structure of
152 * the queue afterward.
154 void blk_freeze_queue(struct request_queue
*q
)
157 * In the !blk_mq case we are only calling this to kill the
158 * q_usage_counter, otherwise this increases the freeze depth
159 * and waits for it to return to zero. For this reason there is
160 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
161 * exported to drivers as the only user for unfreeze is blk_mq.
163 blk_freeze_queue_start(q
);
166 blk_mq_freeze_queue_wait(q
);
169 void blk_mq_freeze_queue(struct request_queue
*q
)
172 * ...just an alias to keep freeze and unfreeze actions balanced
173 * in the blk_mq_* namespace
177 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
179 void blk_mq_unfreeze_queue(struct request_queue
*q
)
183 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
184 WARN_ON_ONCE(freeze_depth
< 0);
186 percpu_ref_reinit(&q
->q_usage_counter
);
187 wake_up_all(&q
->mq_freeze_wq
);
190 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
193 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
194 * mpt3sas driver such that this function can be removed.
196 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
200 spin_lock_irqsave(q
->queue_lock
, flags
);
201 queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
202 spin_unlock_irqrestore(q
->queue_lock
, flags
);
204 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
207 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
210 * Note: this function does not prevent that the struct request end_io()
211 * callback function is invoked. Once this function is returned, we make
212 * sure no dispatch can happen until the queue is unquiesced via
213 * blk_mq_unquiesce_queue().
215 void blk_mq_quiesce_queue(struct request_queue
*q
)
217 struct blk_mq_hw_ctx
*hctx
;
221 blk_mq_quiesce_queue_nowait(q
);
223 queue_for_each_hw_ctx(q
, hctx
, i
) {
224 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
225 synchronize_srcu(hctx
->queue_rq_srcu
);
232 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
235 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
238 * This function recovers queue into the state before quiescing
239 * which is done by blk_mq_quiesce_queue.
241 void blk_mq_unquiesce_queue(struct request_queue
*q
)
245 spin_lock_irqsave(q
->queue_lock
, flags
);
246 queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
247 spin_unlock_irqrestore(q
->queue_lock
, flags
);
249 /* dispatch requests which are inserted during quiescing */
250 blk_mq_run_hw_queues(q
, true);
252 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
254 void blk_mq_wake_waiters(struct request_queue
*q
)
256 struct blk_mq_hw_ctx
*hctx
;
259 queue_for_each_hw_ctx(q
, hctx
, i
)
260 if (blk_mq_hw_queue_mapped(hctx
))
261 blk_mq_tag_wakeup_all(hctx
->tags
, true);
264 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
266 return blk_mq_has_free_tags(hctx
->tags
);
268 EXPORT_SYMBOL(blk_mq_can_queue
);
270 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
271 unsigned int tag
, unsigned int op
)
273 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
274 struct request
*rq
= tags
->static_rqs
[tag
];
278 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
280 rq
->internal_tag
= tag
;
282 if (blk_mq_tag_busy(data
->hctx
)) {
283 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
284 atomic_inc(&data
->hctx
->nr_active
);
287 rq
->internal_tag
= -1;
288 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
291 INIT_LIST_HEAD(&rq
->queuelist
);
292 /* csd/requeue_work/fifo_time is initialized before use */
294 rq
->mq_ctx
= data
->ctx
;
296 if (data
->flags
& BLK_MQ_REQ_PREEMPT
)
297 rq
->rq_flags
|= RQF_PREEMPT
;
298 if (blk_queue_io_stat(data
->q
))
299 rq
->rq_flags
|= RQF_IO_STAT
;
300 /* do not touch atomic flags, it needs atomic ops against the timer */
302 INIT_HLIST_NODE(&rq
->hash
);
303 RB_CLEAR_NODE(&rq
->rb_node
);
306 rq
->start_time
= jiffies
;
307 #ifdef CONFIG_BLK_CGROUP
309 set_start_time_ns(rq
);
310 rq
->io_start_time_ns
= 0;
312 rq
->nr_phys_segments
= 0;
313 #if defined(CONFIG_BLK_DEV_INTEGRITY)
314 rq
->nr_integrity_segments
= 0;
317 /* tag was already set */
320 INIT_LIST_HEAD(&rq
->timeout_list
);
324 rq
->end_io_data
= NULL
;
327 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
331 static struct request
*blk_mq_get_request(struct request_queue
*q
,
332 struct bio
*bio
, unsigned int op
,
333 struct blk_mq_alloc_data
*data
)
335 struct elevator_queue
*e
= q
->elevator
;
338 bool put_ctx_on_error
= false;
340 blk_queue_enter_live(q
);
342 if (likely(!data
->ctx
)) {
343 data
->ctx
= blk_mq_get_ctx(q
);
344 put_ctx_on_error
= true;
346 if (likely(!data
->hctx
))
347 data
->hctx
= blk_mq_map_queue(q
, data
->ctx
->cpu
);
349 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
352 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
355 * Flush requests are special and go directly to the
358 if (!op_is_flush(op
) && e
->type
->ops
.mq
.limit_depth
)
359 e
->type
->ops
.mq
.limit_depth(op
, data
);
362 tag
= blk_mq_get_tag(data
);
363 if (tag
== BLK_MQ_TAG_FAIL
) {
364 if (put_ctx_on_error
) {
365 blk_mq_put_ctx(data
->ctx
);
372 rq
= blk_mq_rq_ctx_init(data
, tag
, op
);
373 if (!op_is_flush(op
)) {
375 if (e
&& e
->type
->ops
.mq
.prepare_request
) {
376 if (e
->type
->icq_cache
&& rq_ioc(bio
))
377 blk_mq_sched_assign_ioc(rq
, bio
);
379 e
->type
->ops
.mq
.prepare_request(rq
, bio
);
380 rq
->rq_flags
|= RQF_ELVPRIV
;
383 data
->hctx
->queued
++;
387 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
388 blk_mq_req_flags_t flags
)
390 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
394 ret
= blk_queue_enter(q
, flags
);
398 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
402 return ERR_PTR(-EWOULDBLOCK
);
404 blk_mq_put_ctx(alloc_data
.ctx
);
407 rq
->__sector
= (sector_t
) -1;
408 rq
->bio
= rq
->biotail
= NULL
;
411 EXPORT_SYMBOL(blk_mq_alloc_request
);
413 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
414 unsigned int op
, blk_mq_req_flags_t flags
, unsigned int hctx_idx
)
416 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
422 * If the tag allocator sleeps we could get an allocation for a
423 * different hardware context. No need to complicate the low level
424 * allocator for this for the rare use case of a command tied to
427 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
428 return ERR_PTR(-EINVAL
);
430 if (hctx_idx
>= q
->nr_hw_queues
)
431 return ERR_PTR(-EIO
);
433 ret
= blk_queue_enter(q
, flags
);
438 * Check if the hardware context is actually mapped to anything.
439 * If not tell the caller that it should skip this queue.
441 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
442 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
444 return ERR_PTR(-EXDEV
);
446 cpu
= cpumask_first_and(alloc_data
.hctx
->cpumask
, cpu_online_mask
);
447 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
449 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
453 return ERR_PTR(-EWOULDBLOCK
);
457 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
459 void blk_mq_free_request(struct request
*rq
)
461 struct request_queue
*q
= rq
->q
;
462 struct elevator_queue
*e
= q
->elevator
;
463 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
464 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
465 const int sched_tag
= rq
->internal_tag
;
467 if (rq
->rq_flags
& RQF_ELVPRIV
) {
468 if (e
&& e
->type
->ops
.mq
.finish_request
)
469 e
->type
->ops
.mq
.finish_request(rq
);
471 put_io_context(rq
->elv
.icq
->ioc
);
476 ctx
->rq_completed
[rq_is_sync(rq
)]++;
477 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
478 atomic_dec(&hctx
->nr_active
);
480 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
481 laptop_io_completion(q
->backing_dev_info
);
483 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
486 blk_put_rl(blk_rq_rl(rq
));
488 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
489 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
491 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
493 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
494 blk_mq_sched_restart(hctx
);
497 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
499 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
501 blk_account_io_done(rq
);
504 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
505 rq
->end_io(rq
, error
);
507 if (unlikely(blk_bidi_rq(rq
)))
508 blk_mq_free_request(rq
->next_rq
);
509 blk_mq_free_request(rq
);
512 EXPORT_SYMBOL(__blk_mq_end_request
);
514 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
516 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
518 __blk_mq_end_request(rq
, error
);
520 EXPORT_SYMBOL(blk_mq_end_request
);
522 static void __blk_mq_complete_request_remote(void *data
)
524 struct request
*rq
= data
;
526 rq
->q
->softirq_done_fn(rq
);
529 static void __blk_mq_complete_request(struct request
*rq
)
531 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
535 if (rq
->internal_tag
!= -1)
536 blk_mq_sched_completed_request(rq
);
537 if (rq
->rq_flags
& RQF_STATS
) {
538 blk_mq_poll_stats_start(rq
->q
);
542 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
543 rq
->q
->softirq_done_fn(rq
);
548 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
549 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
551 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
552 rq
->csd
.func
= __blk_mq_complete_request_remote
;
555 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
557 rq
->q
->softirq_done_fn(rq
);
563 * blk_mq_complete_request - end I/O on a request
564 * @rq: the request being processed
567 * Ends all I/O on a request. It does not handle partial completions.
568 * The actual completion happens out-of-order, through a IPI handler.
570 void blk_mq_complete_request(struct request
*rq
)
572 struct request_queue
*q
= rq
->q
;
574 if (unlikely(blk_should_fake_timeout(q
)))
576 if (!blk_mark_rq_complete(rq
))
577 __blk_mq_complete_request(rq
);
579 EXPORT_SYMBOL(blk_mq_complete_request
);
581 int blk_mq_request_started(struct request
*rq
)
583 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
585 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
587 void blk_mq_start_request(struct request
*rq
)
589 struct request_queue
*q
= rq
->q
;
591 blk_mq_sched_started_request(rq
);
593 trace_block_rq_issue(q
, rq
);
595 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
596 blk_stat_set_issue(&rq
->issue_stat
, blk_rq_sectors(rq
));
597 rq
->rq_flags
|= RQF_STATS
;
598 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
603 WARN_ON_ONCE(test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
));
606 * Mark us as started and clear complete. Complete might have been
607 * set if requeue raced with timeout, which then marked it as
608 * complete. So be sure to clear complete again when we start
609 * the request, otherwise we'll ignore the completion event.
611 * Ensure that ->deadline is visible before we set STARTED, such that
612 * blk_mq_check_expired() is guaranteed to observe our ->deadline when
613 * it observes STARTED.
616 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
617 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
)) {
619 * Coherence order guarantees these consecutive stores to a
620 * single variable propagate in the specified order. Thus the
621 * clear_bit() is ordered _after_ the set bit. See
622 * blk_mq_check_expired().
624 * (the bits must be part of the same byte for this to be
627 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
630 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
632 * Make sure space for the drain appears. We know we can do
633 * this because max_hw_segments has been adjusted to be one
634 * fewer than the device can handle.
636 rq
->nr_phys_segments
++;
639 EXPORT_SYMBOL(blk_mq_start_request
);
642 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
643 * flag isn't set yet, so there may be race with timeout handler,
644 * but given rq->deadline is just set in .queue_rq() under
645 * this situation, the race won't be possible in reality because
646 * rq->timeout should be set as big enough to cover the window
647 * between blk_mq_start_request() called from .queue_rq() and
648 * clearing REQ_ATOM_STARTED here.
650 static void __blk_mq_requeue_request(struct request
*rq
)
652 struct request_queue
*q
= rq
->q
;
654 blk_mq_put_driver_tag(rq
);
656 trace_block_rq_requeue(q
, rq
);
657 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
659 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
660 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
661 rq
->nr_phys_segments
--;
665 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
667 __blk_mq_requeue_request(rq
);
669 /* this request will be re-inserted to io scheduler queue */
670 blk_mq_sched_requeue_request(rq
);
672 BUG_ON(blk_queued_rq(rq
));
673 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
675 EXPORT_SYMBOL(blk_mq_requeue_request
);
677 static void blk_mq_requeue_work(struct work_struct
*work
)
679 struct request_queue
*q
=
680 container_of(work
, struct request_queue
, requeue_work
.work
);
682 struct request
*rq
, *next
;
684 spin_lock_irq(&q
->requeue_lock
);
685 list_splice_init(&q
->requeue_list
, &rq_list
);
686 spin_unlock_irq(&q
->requeue_lock
);
688 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
689 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
692 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
693 list_del_init(&rq
->queuelist
);
694 blk_mq_sched_insert_request(rq
, true, false, false, true);
697 while (!list_empty(&rq_list
)) {
698 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
699 list_del_init(&rq
->queuelist
);
700 blk_mq_sched_insert_request(rq
, false, false, false, true);
703 blk_mq_run_hw_queues(q
, false);
706 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
707 bool kick_requeue_list
)
709 struct request_queue
*q
= rq
->q
;
713 * We abuse this flag that is otherwise used by the I/O scheduler to
714 * request head insertion from the workqueue.
716 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
718 spin_lock_irqsave(&q
->requeue_lock
, flags
);
720 rq
->rq_flags
|= RQF_SOFTBARRIER
;
721 list_add(&rq
->queuelist
, &q
->requeue_list
);
723 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
725 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
727 if (kick_requeue_list
)
728 blk_mq_kick_requeue_list(q
);
730 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
732 void blk_mq_kick_requeue_list(struct request_queue
*q
)
734 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
736 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
738 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
741 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
742 msecs_to_jiffies(msecs
));
744 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
746 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
748 if (tag
< tags
->nr_tags
) {
749 prefetch(tags
->rqs
[tag
]);
750 return tags
->rqs
[tag
];
755 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
757 struct blk_mq_timeout_data
{
759 unsigned int next_set
;
762 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
764 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
765 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
768 * We know that complete is set at this point. If STARTED isn't set
769 * anymore, then the request isn't active and the "timeout" should
770 * just be ignored. This can happen due to the bitflag ordering.
771 * Timeout first checks if STARTED is set, and if it is, assumes
772 * the request is active. But if we race with completion, then
773 * both flags will get cleared. So check here again, and ignore
774 * a timeout event with a request that isn't active.
776 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
780 ret
= ops
->timeout(req
, reserved
);
784 __blk_mq_complete_request(req
);
786 case BLK_EH_RESET_TIMER
:
788 blk_clear_rq_complete(req
);
790 case BLK_EH_NOT_HANDLED
:
793 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
798 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
799 struct request
*rq
, void *priv
, bool reserved
)
801 struct blk_mq_timeout_data
*data
= priv
;
802 unsigned long deadline
;
804 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
808 * Ensures that if we see STARTED we must also see our
809 * up-to-date deadline, see blk_mq_start_request().
813 deadline
= READ_ONCE(rq
->deadline
);
816 * The rq being checked may have been freed and reallocated
817 * out already here, we avoid this race by checking rq->deadline
818 * and REQ_ATOM_COMPLETE flag together:
820 * - if rq->deadline is observed as new value because of
821 * reusing, the rq won't be timed out because of timing.
822 * - if rq->deadline is observed as previous value,
823 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
824 * because we put a barrier between setting rq->deadline
825 * and clearing the flag in blk_mq_start_request(), so
826 * this rq won't be timed out too.
828 if (time_after_eq(jiffies
, deadline
)) {
829 if (!blk_mark_rq_complete(rq
)) {
831 * Again coherence order ensures that consecutive reads
832 * from the same variable must be in that order. This
833 * ensures that if we see COMPLETE clear, we must then
834 * see STARTED set and we'll ignore this timeout.
836 * (There's also the MB implied by the test_and_clear())
838 blk_mq_rq_timed_out(rq
, reserved
);
840 } else if (!data
->next_set
|| time_after(data
->next
, deadline
)) {
841 data
->next
= deadline
;
846 static void blk_mq_timeout_work(struct work_struct
*work
)
848 struct request_queue
*q
=
849 container_of(work
, struct request_queue
, timeout_work
);
850 struct blk_mq_timeout_data data
= {
856 /* A deadlock might occur if a request is stuck requiring a
857 * timeout at the same time a queue freeze is waiting
858 * completion, since the timeout code would not be able to
859 * acquire the queue reference here.
861 * That's why we don't use blk_queue_enter here; instead, we use
862 * percpu_ref_tryget directly, because we need to be able to
863 * obtain a reference even in the short window between the queue
864 * starting to freeze, by dropping the first reference in
865 * blk_freeze_queue_start, and the moment the last request is
866 * consumed, marked by the instant q_usage_counter reaches
869 if (!percpu_ref_tryget(&q
->q_usage_counter
))
872 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
875 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
876 mod_timer(&q
->timeout
, data
.next
);
878 struct blk_mq_hw_ctx
*hctx
;
880 queue_for_each_hw_ctx(q
, hctx
, i
) {
881 /* the hctx may be unmapped, so check it here */
882 if (blk_mq_hw_queue_mapped(hctx
))
883 blk_mq_tag_idle(hctx
);
889 struct flush_busy_ctx_data
{
890 struct blk_mq_hw_ctx
*hctx
;
891 struct list_head
*list
;
894 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
896 struct flush_busy_ctx_data
*flush_data
= data
;
897 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
898 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
900 sbitmap_clear_bit(sb
, bitnr
);
901 spin_lock(&ctx
->lock
);
902 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
903 spin_unlock(&ctx
->lock
);
908 * Process software queues that have been marked busy, splicing them
909 * to the for-dispatch
911 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
913 struct flush_busy_ctx_data data
= {
918 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
920 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
922 struct dispatch_rq_data
{
923 struct blk_mq_hw_ctx
*hctx
;
927 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
930 struct dispatch_rq_data
*dispatch_data
= data
;
931 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
932 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
934 spin_lock(&ctx
->lock
);
935 if (unlikely(!list_empty(&ctx
->rq_list
))) {
936 dispatch_data
->rq
= list_entry_rq(ctx
->rq_list
.next
);
937 list_del_init(&dispatch_data
->rq
->queuelist
);
938 if (list_empty(&ctx
->rq_list
))
939 sbitmap_clear_bit(sb
, bitnr
);
941 spin_unlock(&ctx
->lock
);
943 return !dispatch_data
->rq
;
946 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
947 struct blk_mq_ctx
*start
)
949 unsigned off
= start
? start
->index_hw
: 0;
950 struct dispatch_rq_data data
= {
955 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
956 dispatch_rq_from_ctx
, &data
);
961 static inline unsigned int queued_to_index(unsigned int queued
)
966 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
969 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
972 struct blk_mq_alloc_data data
= {
974 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
975 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
978 might_sleep_if(wait
);
983 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
984 data
.flags
|= BLK_MQ_REQ_RESERVED
;
986 rq
->tag
= blk_mq_get_tag(&data
);
988 if (blk_mq_tag_busy(data
.hctx
)) {
989 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
990 atomic_inc(&data
.hctx
->nr_active
);
992 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
998 return rq
->tag
!= -1;
1001 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
,
1002 int flags
, void *key
)
1004 struct blk_mq_hw_ctx
*hctx
;
1006 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1008 list_del_init(&wait
->entry
);
1009 blk_mq_run_hw_queue(hctx
, true);
1014 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1015 * the tag wakeups. For non-shared tags, we can simply mark us nedeing a
1016 * restart. For both caes, take care to check the condition again after
1017 * marking us as waiting.
1019 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx
**hctx
,
1022 struct blk_mq_hw_ctx
*this_hctx
= *hctx
;
1023 bool shared_tags
= (this_hctx
->flags
& BLK_MQ_F_TAG_SHARED
) != 0;
1024 struct sbq_wait_state
*ws
;
1025 wait_queue_entry_t
*wait
;
1029 if (!test_bit(BLK_MQ_S_SCHED_RESTART
, &this_hctx
->state
))
1030 set_bit(BLK_MQ_S_SCHED_RESTART
, &this_hctx
->state
);
1032 wait
= &this_hctx
->dispatch_wait
;
1033 if (!list_empty_careful(&wait
->entry
))
1036 spin_lock(&this_hctx
->lock
);
1037 if (!list_empty(&wait
->entry
)) {
1038 spin_unlock(&this_hctx
->lock
);
1042 ws
= bt_wait_ptr(&this_hctx
->tags
->bitmap_tags
, this_hctx
);
1043 add_wait_queue(&ws
->wait
, wait
);
1047 * It's possible that a tag was freed in the window between the
1048 * allocation failure and adding the hardware queue to the wait
1051 ret
= blk_mq_get_driver_tag(rq
, hctx
, false);
1055 * Don't clear RESTART here, someone else could have set it.
1056 * At most this will cost an extra queue run.
1061 spin_unlock(&this_hctx
->lock
);
1066 * We got a tag, remove ourselves from the wait queue to ensure
1067 * someone else gets the wakeup.
1069 spin_lock_irq(&ws
->wait
.lock
);
1070 list_del_init(&wait
->entry
);
1071 spin_unlock_irq(&ws
->wait
.lock
);
1072 spin_unlock(&this_hctx
->lock
);
1077 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
,
1080 struct blk_mq_hw_ctx
*hctx
;
1081 struct request
*rq
, *nxt
;
1082 bool no_tag
= false;
1085 if (list_empty(list
))
1088 WARN_ON(!list_is_singular(list
) && got_budget
);
1091 * Now process all the entries, sending them to the driver.
1093 errors
= queued
= 0;
1095 struct blk_mq_queue_data bd
;
1098 rq
= list_first_entry(list
, struct request
, queuelist
);
1100 hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
);
1101 if (!got_budget
&& !blk_mq_get_dispatch_budget(hctx
))
1104 if (!blk_mq_get_driver_tag(rq
, NULL
, false)) {
1106 * The initial allocation attempt failed, so we need to
1107 * rerun the hardware queue when a tag is freed. The
1108 * waitqueue takes care of that. If the queue is run
1109 * before we add this entry back on the dispatch list,
1110 * we'll re-run it below.
1112 if (!blk_mq_mark_tag_wait(&hctx
, rq
)) {
1113 blk_mq_put_dispatch_budget(hctx
);
1115 * For non-shared tags, the RESTART check
1118 if (hctx
->flags
& BLK_MQ_F_TAG_SHARED
)
1124 list_del_init(&rq
->queuelist
);
1129 * Flag last if we have no more requests, or if we have more
1130 * but can't assign a driver tag to it.
1132 if (list_empty(list
))
1135 nxt
= list_first_entry(list
, struct request
, queuelist
);
1136 bd
.last
= !blk_mq_get_driver_tag(nxt
, NULL
, false);
1139 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1140 if (ret
== BLK_STS_RESOURCE
) {
1142 * If an I/O scheduler has been configured and we got a
1143 * driver tag for the next request already, free it
1146 if (!list_empty(list
)) {
1147 nxt
= list_first_entry(list
, struct request
, queuelist
);
1148 blk_mq_put_driver_tag(nxt
);
1150 list_add(&rq
->queuelist
, list
);
1151 __blk_mq_requeue_request(rq
);
1155 if (unlikely(ret
!= BLK_STS_OK
)) {
1157 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1162 } while (!list_empty(list
));
1164 hctx
->dispatched
[queued_to_index(queued
)]++;
1167 * Any items that need requeuing? Stuff them into hctx->dispatch,
1168 * that is where we will continue on next queue run.
1170 if (!list_empty(list
)) {
1171 spin_lock(&hctx
->lock
);
1172 list_splice_init(list
, &hctx
->dispatch
);
1173 spin_unlock(&hctx
->lock
);
1176 * If SCHED_RESTART was set by the caller of this function and
1177 * it is no longer set that means that it was cleared by another
1178 * thread and hence that a queue rerun is needed.
1180 * If 'no_tag' is set, that means that we failed getting
1181 * a driver tag with an I/O scheduler attached. If our dispatch
1182 * waitqueue is no longer active, ensure that we run the queue
1183 * AFTER adding our entries back to the list.
1185 * If no I/O scheduler has been configured it is possible that
1186 * the hardware queue got stopped and restarted before requests
1187 * were pushed back onto the dispatch list. Rerun the queue to
1188 * avoid starvation. Notes:
1189 * - blk_mq_run_hw_queue() checks whether or not a queue has
1190 * been stopped before rerunning a queue.
1191 * - Some but not all block drivers stop a queue before
1192 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1195 if (!blk_mq_sched_needs_restart(hctx
) ||
1196 (no_tag
&& list_empty_careful(&hctx
->dispatch_wait
.entry
)))
1197 blk_mq_run_hw_queue(hctx
, true);
1200 return (queued
+ errors
) != 0;
1203 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1208 * We should be running this queue from one of the CPUs that
1211 * There are at least two related races now between setting
1212 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1213 * __blk_mq_run_hw_queue():
1215 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1216 * but later it becomes online, then this warning is harmless
1219 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1220 * but later it becomes offline, then the warning can't be
1221 * triggered, and we depend on blk-mq timeout handler to
1222 * handle dispatched requests to this hctx
1224 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1225 cpu_online(hctx
->next_cpu
)) {
1226 printk(KERN_WARNING
"run queue from wrong CPU %d, hctx %s\n",
1227 raw_smp_processor_id(),
1228 cpumask_empty(hctx
->cpumask
) ? "inactive": "active");
1233 * We can't run the queue inline with ints disabled. Ensure that
1234 * we catch bad users of this early.
1236 WARN_ON_ONCE(in_interrupt());
1238 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1240 blk_mq_sched_dispatch_requests(hctx
);
1245 srcu_idx
= srcu_read_lock(hctx
->queue_rq_srcu
);
1246 blk_mq_sched_dispatch_requests(hctx
);
1247 srcu_read_unlock(hctx
->queue_rq_srcu
, srcu_idx
);
1252 * It'd be great if the workqueue API had a way to pass
1253 * in a mask and had some smarts for more clever placement.
1254 * For now we just round-robin here, switching for every
1255 * BLK_MQ_CPU_WORK_BATCH queued items.
1257 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1259 if (hctx
->queue
->nr_hw_queues
== 1)
1260 return WORK_CPU_UNBOUND
;
1262 if (--hctx
->next_cpu_batch
<= 0) {
1265 next_cpu
= cpumask_next_and(hctx
->next_cpu
, hctx
->cpumask
,
1267 if (next_cpu
>= nr_cpu_ids
)
1268 next_cpu
= cpumask_first_and(hctx
->cpumask
,cpu_online_mask
);
1270 hctx
->next_cpu
= next_cpu
;
1271 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1274 return hctx
->next_cpu
;
1277 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1278 unsigned long msecs
)
1280 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1283 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1286 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1287 int cpu
= get_cpu();
1288 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1289 __blk_mq_run_hw_queue(hctx
);
1297 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1299 msecs_to_jiffies(msecs
));
1302 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1304 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1306 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1308 bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1310 if (blk_mq_hctx_has_pending(hctx
)) {
1311 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1317 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1319 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1321 struct blk_mq_hw_ctx
*hctx
;
1324 queue_for_each_hw_ctx(q
, hctx
, i
) {
1325 if (blk_mq_hctx_stopped(hctx
))
1328 blk_mq_run_hw_queue(hctx
, async
);
1331 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1334 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1335 * @q: request queue.
1337 * The caller is responsible for serializing this function against
1338 * blk_mq_{start,stop}_hw_queue().
1340 bool blk_mq_queue_stopped(struct request_queue
*q
)
1342 struct blk_mq_hw_ctx
*hctx
;
1345 queue_for_each_hw_ctx(q
, hctx
, i
)
1346 if (blk_mq_hctx_stopped(hctx
))
1351 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1354 * This function is often used for pausing .queue_rq() by driver when
1355 * there isn't enough resource or some conditions aren't satisfied, and
1356 * BLK_STS_RESOURCE is usually returned.
1358 * We do not guarantee that dispatch can be drained or blocked
1359 * after blk_mq_stop_hw_queue() returns. Please use
1360 * blk_mq_quiesce_queue() for that requirement.
1362 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1364 cancel_delayed_work(&hctx
->run_work
);
1366 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1368 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1371 * This function is often used for pausing .queue_rq() by driver when
1372 * there isn't enough resource or some conditions aren't satisfied, and
1373 * BLK_STS_RESOURCE is usually returned.
1375 * We do not guarantee that dispatch can be drained or blocked
1376 * after blk_mq_stop_hw_queues() returns. Please use
1377 * blk_mq_quiesce_queue() for that requirement.
1379 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1381 struct blk_mq_hw_ctx
*hctx
;
1384 queue_for_each_hw_ctx(q
, hctx
, i
)
1385 blk_mq_stop_hw_queue(hctx
);
1387 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1389 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1391 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1393 blk_mq_run_hw_queue(hctx
, false);
1395 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1397 void blk_mq_start_hw_queues(struct request_queue
*q
)
1399 struct blk_mq_hw_ctx
*hctx
;
1402 queue_for_each_hw_ctx(q
, hctx
, i
)
1403 blk_mq_start_hw_queue(hctx
);
1405 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1407 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1409 if (!blk_mq_hctx_stopped(hctx
))
1412 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1413 blk_mq_run_hw_queue(hctx
, async
);
1415 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1417 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1419 struct blk_mq_hw_ctx
*hctx
;
1422 queue_for_each_hw_ctx(q
, hctx
, i
)
1423 blk_mq_start_stopped_hw_queue(hctx
, async
);
1425 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1427 static void blk_mq_run_work_fn(struct work_struct
*work
)
1429 struct blk_mq_hw_ctx
*hctx
;
1431 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1434 * If we are stopped, don't run the queue. The exception is if
1435 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1436 * the STOPPED bit and run it.
1438 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)) {
1439 if (!test_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
))
1442 clear_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1443 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1446 __blk_mq_run_hw_queue(hctx
);
1450 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1452 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1456 * Stop the hw queue, then modify currently delayed work.
1457 * This should prevent us from running the queue prematurely.
1458 * Mark the queue as auto-clearing STOPPED when it runs.
1460 blk_mq_stop_hw_queue(hctx
);
1461 set_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1462 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1464 msecs_to_jiffies(msecs
));
1466 EXPORT_SYMBOL(blk_mq_delay_queue
);
1468 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1472 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1474 lockdep_assert_held(&ctx
->lock
);
1476 trace_block_rq_insert(hctx
->queue
, rq
);
1479 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1481 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1484 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1487 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1489 lockdep_assert_held(&ctx
->lock
);
1491 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1492 blk_mq_hctx_mark_pending(hctx
, ctx
);
1496 * Should only be used carefully, when the caller knows we want to
1497 * bypass a potential IO scheduler on the target device.
1499 void blk_mq_request_bypass_insert(struct request
*rq
, bool run_queue
)
1501 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1502 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(rq
->q
, ctx
->cpu
);
1504 spin_lock(&hctx
->lock
);
1505 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1506 spin_unlock(&hctx
->lock
);
1509 blk_mq_run_hw_queue(hctx
, false);
1512 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1513 struct list_head
*list
)
1517 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1520 spin_lock(&ctx
->lock
);
1521 while (!list_empty(list
)) {
1524 rq
= list_first_entry(list
, struct request
, queuelist
);
1525 BUG_ON(rq
->mq_ctx
!= ctx
);
1526 list_del_init(&rq
->queuelist
);
1527 __blk_mq_insert_req_list(hctx
, rq
, false);
1529 blk_mq_hctx_mark_pending(hctx
, ctx
);
1530 spin_unlock(&ctx
->lock
);
1533 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1535 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1536 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1538 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1539 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1540 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1543 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1545 struct blk_mq_ctx
*this_ctx
;
1546 struct request_queue
*this_q
;
1549 LIST_HEAD(ctx_list
);
1552 list_splice_init(&plug
->mq_list
, &list
);
1554 list_sort(NULL
, &list
, plug_ctx_cmp
);
1560 while (!list_empty(&list
)) {
1561 rq
= list_entry_rq(list
.next
);
1562 list_del_init(&rq
->queuelist
);
1564 if (rq
->mq_ctx
!= this_ctx
) {
1566 trace_block_unplug(this_q
, depth
, from_schedule
);
1567 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1572 this_ctx
= rq
->mq_ctx
;
1578 list_add_tail(&rq
->queuelist
, &ctx_list
);
1582 * If 'this_ctx' is set, we know we have entries to complete
1583 * on 'ctx_list'. Do those.
1586 trace_block_unplug(this_q
, depth
, from_schedule
);
1587 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1592 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1594 blk_init_request_from_bio(rq
, bio
);
1596 blk_rq_set_rl(rq
, blk_get_rl(rq
->q
, bio
));
1598 blk_account_io_start(rq
, true);
1601 static inline void blk_mq_queue_io(struct blk_mq_hw_ctx
*hctx
,
1602 struct blk_mq_ctx
*ctx
,
1605 spin_lock(&ctx
->lock
);
1606 __blk_mq_insert_request(hctx
, rq
, false);
1607 spin_unlock(&ctx
->lock
);
1610 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1613 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1615 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1618 static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1620 blk_qc_t
*cookie
, bool may_sleep
)
1622 struct request_queue
*q
= rq
->q
;
1623 struct blk_mq_queue_data bd
= {
1627 blk_qc_t new_cookie
;
1629 bool run_queue
= true;
1631 /* RCU or SRCU read lock is needed before checking quiesced flag */
1632 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1640 if (!blk_mq_get_dispatch_budget(hctx
))
1643 if (!blk_mq_get_driver_tag(rq
, NULL
, false)) {
1644 blk_mq_put_dispatch_budget(hctx
);
1648 new_cookie
= request_to_qc_t(hctx
, rq
);
1651 * For OK queue, we are done. For error, kill it. Any other
1652 * error (busy), just add it to our list as we previously
1655 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1658 *cookie
= new_cookie
;
1660 case BLK_STS_RESOURCE
:
1661 __blk_mq_requeue_request(rq
);
1664 *cookie
= BLK_QC_T_NONE
;
1665 blk_mq_end_request(rq
, ret
);
1670 blk_mq_sched_insert_request(rq
, false, run_queue
, false, may_sleep
);
1673 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1674 struct request
*rq
, blk_qc_t
*cookie
)
1676 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1678 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false);
1681 unsigned int srcu_idx
;
1685 srcu_idx
= srcu_read_lock(hctx
->queue_rq_srcu
);
1686 __blk_mq_try_issue_directly(hctx
, rq
, cookie
, true);
1687 srcu_read_unlock(hctx
->queue_rq_srcu
, srcu_idx
);
1691 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1693 const int is_sync
= op_is_sync(bio
->bi_opf
);
1694 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1695 struct blk_mq_alloc_data data
= { .flags
= 0 };
1697 unsigned int request_count
= 0;
1698 struct blk_plug
*plug
;
1699 struct request
*same_queue_rq
= NULL
;
1701 unsigned int wb_acct
;
1703 blk_queue_bounce(q
, &bio
);
1705 blk_queue_split(q
, &bio
);
1707 if (!bio_integrity_prep(bio
))
1708 return BLK_QC_T_NONE
;
1710 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1711 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1712 return BLK_QC_T_NONE
;
1714 if (blk_mq_sched_bio_merge(q
, bio
))
1715 return BLK_QC_T_NONE
;
1717 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1719 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1721 rq
= blk_mq_get_request(q
, bio
, bio
->bi_opf
, &data
);
1722 if (unlikely(!rq
)) {
1723 __wbt_done(q
->rq_wb
, wb_acct
);
1724 if (bio
->bi_opf
& REQ_NOWAIT
)
1725 bio_wouldblock_error(bio
);
1726 return BLK_QC_T_NONE
;
1729 wbt_track(&rq
->issue_stat
, wb_acct
);
1731 cookie
= request_to_qc_t(data
.hctx
, rq
);
1733 plug
= current
->plug
;
1734 if (unlikely(is_flush_fua
)) {
1735 blk_mq_put_ctx(data
.ctx
);
1736 blk_mq_bio_to_request(rq
, bio
);
1738 /* bypass scheduler for flush rq */
1739 blk_insert_flush(rq
);
1740 blk_mq_run_hw_queue(data
.hctx
, true);
1741 } else if (plug
&& q
->nr_hw_queues
== 1) {
1742 struct request
*last
= NULL
;
1744 blk_mq_put_ctx(data
.ctx
);
1745 blk_mq_bio_to_request(rq
, bio
);
1748 * @request_count may become stale because of schedule
1749 * out, so check the list again.
1751 if (list_empty(&plug
->mq_list
))
1753 else if (blk_queue_nomerges(q
))
1754 request_count
= blk_plug_queued_count(q
);
1757 trace_block_plug(q
);
1759 last
= list_entry_rq(plug
->mq_list
.prev
);
1761 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1762 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1763 blk_flush_plug_list(plug
, false);
1764 trace_block_plug(q
);
1767 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1768 } else if (plug
&& !blk_queue_nomerges(q
)) {
1769 blk_mq_bio_to_request(rq
, bio
);
1772 * We do limited plugging. If the bio can be merged, do that.
1773 * Otherwise the existing request in the plug list will be
1774 * issued. So the plug list will have one request at most
1775 * The plug list might get flushed before this. If that happens,
1776 * the plug list is empty, and same_queue_rq is invalid.
1778 if (list_empty(&plug
->mq_list
))
1779 same_queue_rq
= NULL
;
1781 list_del_init(&same_queue_rq
->queuelist
);
1782 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1784 blk_mq_put_ctx(data
.ctx
);
1786 if (same_queue_rq
) {
1787 data
.hctx
= blk_mq_map_queue(q
,
1788 same_queue_rq
->mq_ctx
->cpu
);
1789 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
1792 } else if (q
->nr_hw_queues
> 1 && is_sync
) {
1793 blk_mq_put_ctx(data
.ctx
);
1794 blk_mq_bio_to_request(rq
, bio
);
1795 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
1796 } else if (q
->elevator
) {
1797 blk_mq_put_ctx(data
.ctx
);
1798 blk_mq_bio_to_request(rq
, bio
);
1799 blk_mq_sched_insert_request(rq
, false, true, true, true);
1801 blk_mq_put_ctx(data
.ctx
);
1802 blk_mq_bio_to_request(rq
, bio
);
1803 blk_mq_queue_io(data
.hctx
, data
.ctx
, rq
);
1804 blk_mq_run_hw_queue(data
.hctx
, true);
1810 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1811 unsigned int hctx_idx
)
1815 if (tags
->rqs
&& set
->ops
->exit_request
) {
1818 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1819 struct request
*rq
= tags
->static_rqs
[i
];
1823 set
->ops
->exit_request(set
, rq
, hctx_idx
);
1824 tags
->static_rqs
[i
] = NULL
;
1828 while (!list_empty(&tags
->page_list
)) {
1829 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1830 list_del_init(&page
->lru
);
1832 * Remove kmemleak object previously allocated in
1833 * blk_mq_init_rq_map().
1835 kmemleak_free(page_address(page
));
1836 __free_pages(page
, page
->private);
1840 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1844 kfree(tags
->static_rqs
);
1845 tags
->static_rqs
= NULL
;
1847 blk_mq_free_tags(tags
);
1850 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1851 unsigned int hctx_idx
,
1852 unsigned int nr_tags
,
1853 unsigned int reserved_tags
)
1855 struct blk_mq_tags
*tags
;
1858 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1859 if (node
== NUMA_NO_NODE
)
1860 node
= set
->numa_node
;
1862 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
1863 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1867 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1868 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1871 blk_mq_free_tags(tags
);
1875 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1876 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1878 if (!tags
->static_rqs
) {
1880 blk_mq_free_tags(tags
);
1887 static size_t order_to_size(unsigned int order
)
1889 return (size_t)PAGE_SIZE
<< order
;
1892 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1893 unsigned int hctx_idx
, unsigned int depth
)
1895 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1896 size_t rq_size
, left
;
1899 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1900 if (node
== NUMA_NO_NODE
)
1901 node
= set
->numa_node
;
1903 INIT_LIST_HEAD(&tags
->page_list
);
1906 * rq_size is the size of the request plus driver payload, rounded
1907 * to the cacheline size
1909 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1911 left
= rq_size
* depth
;
1913 for (i
= 0; i
< depth
; ) {
1914 int this_order
= max_order
;
1919 while (this_order
&& left
< order_to_size(this_order
- 1))
1923 page
= alloc_pages_node(node
,
1924 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1930 if (order_to_size(this_order
) < rq_size
)
1937 page
->private = this_order
;
1938 list_add_tail(&page
->lru
, &tags
->page_list
);
1940 p
= page_address(page
);
1942 * Allow kmemleak to scan these pages as they contain pointers
1943 * to additional allocations like via ops->init_request().
1945 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1946 entries_per_page
= order_to_size(this_order
) / rq_size
;
1947 to_do
= min(entries_per_page
, depth
- i
);
1948 left
-= to_do
* rq_size
;
1949 for (j
= 0; j
< to_do
; j
++) {
1950 struct request
*rq
= p
;
1952 tags
->static_rqs
[i
] = rq
;
1953 if (set
->ops
->init_request
) {
1954 if (set
->ops
->init_request(set
, rq
, hctx_idx
,
1956 tags
->static_rqs
[i
] = NULL
;
1968 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1973 * 'cpu' is going away. splice any existing rq_list entries from this
1974 * software queue to the hw queue dispatch list, and ensure that it
1977 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1979 struct blk_mq_hw_ctx
*hctx
;
1980 struct blk_mq_ctx
*ctx
;
1983 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1984 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1986 spin_lock(&ctx
->lock
);
1987 if (!list_empty(&ctx
->rq_list
)) {
1988 list_splice_init(&ctx
->rq_list
, &tmp
);
1989 blk_mq_hctx_clear_pending(hctx
, ctx
);
1991 spin_unlock(&ctx
->lock
);
1993 if (list_empty(&tmp
))
1996 spin_lock(&hctx
->lock
);
1997 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1998 spin_unlock(&hctx
->lock
);
2000 blk_mq_run_hw_queue(hctx
, true);
2004 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2006 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2010 /* hctx->ctxs will be freed in queue's release handler */
2011 static void blk_mq_exit_hctx(struct request_queue
*q
,
2012 struct blk_mq_tag_set
*set
,
2013 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2015 blk_mq_debugfs_unregister_hctx(hctx
);
2017 if (blk_mq_hw_queue_mapped(hctx
))
2018 blk_mq_tag_idle(hctx
);
2020 if (set
->ops
->exit_request
)
2021 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2023 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
2025 if (set
->ops
->exit_hctx
)
2026 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2028 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2029 cleanup_srcu_struct(hctx
->queue_rq_srcu
);
2031 blk_mq_remove_cpuhp(hctx
);
2032 blk_free_flush_queue(hctx
->fq
);
2033 sbitmap_free(&hctx
->ctx_map
);
2036 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2037 struct blk_mq_tag_set
*set
, int nr_queue
)
2039 struct blk_mq_hw_ctx
*hctx
;
2042 queue_for_each_hw_ctx(q
, hctx
, i
) {
2045 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2049 static int blk_mq_init_hctx(struct request_queue
*q
,
2050 struct blk_mq_tag_set
*set
,
2051 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2055 node
= hctx
->numa_node
;
2056 if (node
== NUMA_NO_NODE
)
2057 node
= hctx
->numa_node
= set
->numa_node
;
2059 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2060 spin_lock_init(&hctx
->lock
);
2061 INIT_LIST_HEAD(&hctx
->dispatch
);
2063 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
2065 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2067 hctx
->tags
= set
->tags
[hctx_idx
];
2070 * Allocate space for all possible cpus to avoid allocation at
2073 hctx
->ctxs
= kmalloc_array_node(nr_cpu_ids
, sizeof(void *),
2076 goto unregister_cpu_notifier
;
2078 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
2084 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
2085 INIT_LIST_HEAD(&hctx
->dispatch_wait
.entry
);
2087 if (set
->ops
->init_hctx
&&
2088 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2091 if (blk_mq_sched_init_hctx(q
, hctx
, hctx_idx
))
2094 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
2096 goto sched_exit_hctx
;
2098 if (set
->ops
->init_request
&&
2099 set
->ops
->init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
2103 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2104 init_srcu_struct(hctx
->queue_rq_srcu
);
2106 blk_mq_debugfs_register_hctx(q
, hctx
);
2113 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
2115 if (set
->ops
->exit_hctx
)
2116 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2118 sbitmap_free(&hctx
->ctx_map
);
2121 unregister_cpu_notifier
:
2122 blk_mq_remove_cpuhp(hctx
);
2126 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2127 unsigned int nr_hw_queues
)
2131 for_each_possible_cpu(i
) {
2132 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2133 struct blk_mq_hw_ctx
*hctx
;
2136 spin_lock_init(&__ctx
->lock
);
2137 INIT_LIST_HEAD(&__ctx
->rq_list
);
2141 * Set local node, IFF we have more than one hw queue. If
2142 * not, we remain on the home node of the device
2144 hctx
= blk_mq_map_queue(q
, i
);
2145 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2146 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2150 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2154 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2155 set
->queue_depth
, set
->reserved_tags
);
2156 if (!set
->tags
[hctx_idx
])
2159 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2164 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2165 set
->tags
[hctx_idx
] = NULL
;
2169 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2170 unsigned int hctx_idx
)
2172 if (set
->tags
[hctx_idx
]) {
2173 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2174 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2175 set
->tags
[hctx_idx
] = NULL
;
2179 static void blk_mq_map_swqueue(struct request_queue
*q
)
2181 unsigned int i
, hctx_idx
;
2182 struct blk_mq_hw_ctx
*hctx
;
2183 struct blk_mq_ctx
*ctx
;
2184 struct blk_mq_tag_set
*set
= q
->tag_set
;
2187 * Avoid others reading imcomplete hctx->cpumask through sysfs
2189 mutex_lock(&q
->sysfs_lock
);
2191 queue_for_each_hw_ctx(q
, hctx
, i
) {
2192 cpumask_clear(hctx
->cpumask
);
2197 * Map software to hardware queues.
2199 * If the cpu isn't present, the cpu is mapped to first hctx.
2201 for_each_possible_cpu(i
) {
2202 hctx_idx
= q
->mq_map
[i
];
2203 /* unmapped hw queue can be remapped after CPU topo changed */
2204 if (!set
->tags
[hctx_idx
] &&
2205 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2207 * If tags initialization fail for some hctx,
2208 * that hctx won't be brought online. In this
2209 * case, remap the current ctx to hctx[0] which
2210 * is guaranteed to always have tags allocated
2215 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2216 hctx
= blk_mq_map_queue(q
, i
);
2218 cpumask_set_cpu(i
, hctx
->cpumask
);
2219 ctx
->index_hw
= hctx
->nr_ctx
;
2220 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2223 mutex_unlock(&q
->sysfs_lock
);
2225 queue_for_each_hw_ctx(q
, hctx
, i
) {
2227 * If no software queues are mapped to this hardware queue,
2228 * disable it and free the request entries.
2230 if (!hctx
->nr_ctx
) {
2231 /* Never unmap queue 0. We need it as a
2232 * fallback in case of a new remap fails
2235 if (i
&& set
->tags
[i
])
2236 blk_mq_free_map_and_requests(set
, i
);
2242 hctx
->tags
= set
->tags
[i
];
2243 WARN_ON(!hctx
->tags
);
2246 * Set the map size to the number of mapped software queues.
2247 * This is more accurate and more efficient than looping
2248 * over all possibly mapped software queues.
2250 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2253 * Initialize batch roundrobin counts
2255 hctx
->next_cpu
= cpumask_first_and(hctx
->cpumask
,
2257 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2262 * Caller needs to ensure that we're either frozen/quiesced, or that
2263 * the queue isn't live yet.
2265 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2267 struct blk_mq_hw_ctx
*hctx
;
2270 queue_for_each_hw_ctx(q
, hctx
, i
) {
2272 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2273 atomic_inc(&q
->shared_hctx_restart
);
2274 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2276 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2277 atomic_dec(&q
->shared_hctx_restart
);
2278 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2283 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2286 struct request_queue
*q
;
2288 lockdep_assert_held(&set
->tag_list_lock
);
2290 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2291 blk_mq_freeze_queue(q
);
2292 queue_set_hctx_shared(q
, shared
);
2293 blk_mq_unfreeze_queue(q
);
2297 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2299 struct blk_mq_tag_set
*set
= q
->tag_set
;
2301 mutex_lock(&set
->tag_list_lock
);
2302 list_del_rcu(&q
->tag_set_list
);
2303 INIT_LIST_HEAD(&q
->tag_set_list
);
2304 if (list_is_singular(&set
->tag_list
)) {
2305 /* just transitioned to unshared */
2306 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2307 /* update existing queue */
2308 blk_mq_update_tag_set_depth(set
, false);
2310 mutex_unlock(&set
->tag_list_lock
);
2315 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2316 struct request_queue
*q
)
2320 mutex_lock(&set
->tag_list_lock
);
2323 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2325 if (!list_empty(&set
->tag_list
) &&
2326 !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2327 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2328 /* update existing queue */
2329 blk_mq_update_tag_set_depth(set
, true);
2331 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2332 queue_set_hctx_shared(q
, true);
2333 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2335 mutex_unlock(&set
->tag_list_lock
);
2339 * It is the actual release handler for mq, but we do it from
2340 * request queue's release handler for avoiding use-after-free
2341 * and headache because q->mq_kobj shouldn't have been introduced,
2342 * but we can't group ctx/kctx kobj without it.
2344 void blk_mq_release(struct request_queue
*q
)
2346 struct blk_mq_hw_ctx
*hctx
;
2349 /* hctx kobj stays in hctx */
2350 queue_for_each_hw_ctx(q
, hctx
, i
) {
2353 kobject_put(&hctx
->kobj
);
2358 kfree(q
->queue_hw_ctx
);
2361 * release .mq_kobj and sw queue's kobject now because
2362 * both share lifetime with request queue.
2364 blk_mq_sysfs_deinit(q
);
2366 free_percpu(q
->queue_ctx
);
2369 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2371 struct request_queue
*uninit_q
, *q
;
2373 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2375 return ERR_PTR(-ENOMEM
);
2377 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2379 blk_cleanup_queue(uninit_q
);
2383 EXPORT_SYMBOL(blk_mq_init_queue
);
2385 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2387 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2389 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, queue_rq_srcu
),
2390 __alignof__(struct blk_mq_hw_ctx
)) !=
2391 sizeof(struct blk_mq_hw_ctx
));
2393 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2394 hw_ctx_size
+= sizeof(struct srcu_struct
);
2399 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2400 struct request_queue
*q
)
2403 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2405 blk_mq_sysfs_unregister(q
);
2407 /* protect against switching io scheduler */
2408 mutex_lock(&q
->sysfs_lock
);
2409 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2415 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2416 hctxs
[i
] = kzalloc_node(blk_mq_hw_ctx_size(set
),
2421 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2428 atomic_set(&hctxs
[i
]->nr_active
, 0);
2429 hctxs
[i
]->numa_node
= node
;
2430 hctxs
[i
]->queue_num
= i
;
2432 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2433 free_cpumask_var(hctxs
[i
]->cpumask
);
2438 blk_mq_hctx_kobj_init(hctxs
[i
]);
2440 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2441 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2445 blk_mq_free_map_and_requests(set
, j
);
2446 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2447 kobject_put(&hctx
->kobj
);
2452 q
->nr_hw_queues
= i
;
2453 mutex_unlock(&q
->sysfs_lock
);
2454 blk_mq_sysfs_register(q
);
2457 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2458 struct request_queue
*q
)
2460 /* mark the queue as mq asap */
2461 q
->mq_ops
= set
->ops
;
2463 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2464 blk_mq_poll_stats_bkt
,
2465 BLK_MQ_POLL_STATS_BKTS
, q
);
2469 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2473 /* init q->mq_kobj and sw queues' kobjects */
2474 blk_mq_sysfs_init(q
);
2476 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2477 GFP_KERNEL
, set
->numa_node
);
2478 if (!q
->queue_hw_ctx
)
2481 q
->mq_map
= set
->mq_map
;
2483 blk_mq_realloc_hw_ctxs(set
, q
);
2484 if (!q
->nr_hw_queues
)
2487 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2488 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2490 q
->nr_queues
= nr_cpu_ids
;
2492 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2494 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2495 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2497 q
->sg_reserved_size
= INT_MAX
;
2499 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2500 INIT_LIST_HEAD(&q
->requeue_list
);
2501 spin_lock_init(&q
->requeue_lock
);
2503 blk_queue_make_request(q
, blk_mq_make_request
);
2504 if (q
->mq_ops
->poll
)
2505 q
->poll_fn
= blk_mq_poll
;
2508 * Do this after blk_queue_make_request() overrides it...
2510 q
->nr_requests
= set
->queue_depth
;
2513 * Default to classic polling
2517 if (set
->ops
->complete
)
2518 blk_queue_softirq_done(q
, set
->ops
->complete
);
2520 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2521 blk_mq_add_queue_tag_set(set
, q
);
2522 blk_mq_map_swqueue(q
);
2524 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2527 ret
= blk_mq_sched_init(q
);
2529 return ERR_PTR(ret
);
2535 kfree(q
->queue_hw_ctx
);
2537 free_percpu(q
->queue_ctx
);
2540 return ERR_PTR(-ENOMEM
);
2542 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2544 void blk_mq_free_queue(struct request_queue
*q
)
2546 struct blk_mq_tag_set
*set
= q
->tag_set
;
2548 blk_mq_del_queue_tag_set(q
);
2549 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2552 /* Basically redo blk_mq_init_queue with queue frozen */
2553 static void blk_mq_queue_reinit(struct request_queue
*q
)
2555 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2557 blk_mq_debugfs_unregister_hctxs(q
);
2558 blk_mq_sysfs_unregister(q
);
2561 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2562 * we should change hctx numa_node according to the new topology (this
2563 * involves freeing and re-allocating memory, worth doing?)
2565 blk_mq_map_swqueue(q
);
2567 blk_mq_sysfs_register(q
);
2568 blk_mq_debugfs_register_hctxs(q
);
2571 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2575 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2576 if (!__blk_mq_alloc_rq_map(set
, i
))
2583 blk_mq_free_rq_map(set
->tags
[i
]);
2589 * Allocate the request maps associated with this tag_set. Note that this
2590 * may reduce the depth asked for, if memory is tight. set->queue_depth
2591 * will be updated to reflect the allocated depth.
2593 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2598 depth
= set
->queue_depth
;
2600 err
= __blk_mq_alloc_rq_maps(set
);
2604 set
->queue_depth
>>= 1;
2605 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2609 } while (set
->queue_depth
);
2611 if (!set
->queue_depth
|| err
) {
2612 pr_err("blk-mq: failed to allocate request map\n");
2616 if (depth
!= set
->queue_depth
)
2617 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2618 depth
, set
->queue_depth
);
2623 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2625 if (set
->ops
->map_queues
) {
2628 * transport .map_queues is usually done in the following
2631 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
2632 * mask = get_cpu_mask(queue)
2633 * for_each_cpu(cpu, mask)
2634 * set->mq_map[cpu] = queue;
2637 * When we need to remap, the table has to be cleared for
2638 * killing stale mapping since one CPU may not be mapped
2641 for_each_possible_cpu(cpu
)
2642 set
->mq_map
[cpu
] = 0;
2644 return set
->ops
->map_queues(set
);
2646 return blk_mq_map_queues(set
);
2650 * Alloc a tag set to be associated with one or more request queues.
2651 * May fail with EINVAL for various error conditions. May adjust the
2652 * requested depth down, if if it too large. In that case, the set
2653 * value will be stored in set->queue_depth.
2655 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2659 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2661 if (!set
->nr_hw_queues
)
2663 if (!set
->queue_depth
)
2665 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2668 if (!set
->ops
->queue_rq
)
2671 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
2674 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2675 pr_info("blk-mq: reduced tag depth to %u\n",
2677 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2681 * If a crashdump is active, then we are potentially in a very
2682 * memory constrained environment. Limit us to 1 queue and
2683 * 64 tags to prevent using too much memory.
2685 if (is_kdump_kernel()) {
2686 set
->nr_hw_queues
= 1;
2687 set
->queue_depth
= min(64U, set
->queue_depth
);
2690 * There is no use for more h/w queues than cpus.
2692 if (set
->nr_hw_queues
> nr_cpu_ids
)
2693 set
->nr_hw_queues
= nr_cpu_ids
;
2695 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2696 GFP_KERNEL
, set
->numa_node
);
2701 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2702 GFP_KERNEL
, set
->numa_node
);
2706 ret
= blk_mq_update_queue_map(set
);
2708 goto out_free_mq_map
;
2710 ret
= blk_mq_alloc_rq_maps(set
);
2712 goto out_free_mq_map
;
2714 mutex_init(&set
->tag_list_lock
);
2715 INIT_LIST_HEAD(&set
->tag_list
);
2727 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2729 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2733 for (i
= 0; i
< nr_cpu_ids
; i
++)
2734 blk_mq_free_map_and_requests(set
, i
);
2742 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2744 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2746 struct blk_mq_tag_set
*set
= q
->tag_set
;
2747 struct blk_mq_hw_ctx
*hctx
;
2753 blk_mq_freeze_queue(q
);
2756 queue_for_each_hw_ctx(q
, hctx
, i
) {
2760 * If we're using an MQ scheduler, just update the scheduler
2761 * queue depth. This is similar to what the old code would do.
2763 if (!hctx
->sched_tags
) {
2764 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
2767 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2775 q
->nr_requests
= nr
;
2777 blk_mq_unfreeze_queue(q
);
2782 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
2785 struct request_queue
*q
;
2787 lockdep_assert_held(&set
->tag_list_lock
);
2789 if (nr_hw_queues
> nr_cpu_ids
)
2790 nr_hw_queues
= nr_cpu_ids
;
2791 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2794 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2795 blk_mq_freeze_queue(q
);
2797 set
->nr_hw_queues
= nr_hw_queues
;
2798 blk_mq_update_queue_map(set
);
2799 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2800 blk_mq_realloc_hw_ctxs(set
, q
);
2801 blk_mq_queue_reinit(q
);
2804 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2805 blk_mq_unfreeze_queue(q
);
2808 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2810 mutex_lock(&set
->tag_list_lock
);
2811 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
2812 mutex_unlock(&set
->tag_list_lock
);
2814 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2816 /* Enable polling stats and return whether they were already enabled. */
2817 static bool blk_poll_stats_enable(struct request_queue
*q
)
2819 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2820 test_and_set_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
))
2822 blk_stat_add_callback(q
, q
->poll_cb
);
2826 static void blk_mq_poll_stats_start(struct request_queue
*q
)
2829 * We don't arm the callback if polling stats are not enabled or the
2830 * callback is already active.
2832 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2833 blk_stat_is_active(q
->poll_cb
))
2836 blk_stat_activate_msecs(q
->poll_cb
, 100);
2839 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
2841 struct request_queue
*q
= cb
->data
;
2844 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
2845 if (cb
->stat
[bucket
].nr_samples
)
2846 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
2850 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2851 struct blk_mq_hw_ctx
*hctx
,
2854 unsigned long ret
= 0;
2858 * If stats collection isn't on, don't sleep but turn it on for
2861 if (!blk_poll_stats_enable(q
))
2865 * As an optimistic guess, use half of the mean service time
2866 * for this type of request. We can (and should) make this smarter.
2867 * For instance, if the completion latencies are tight, we can
2868 * get closer than just half the mean. This is especially
2869 * important on devices where the completion latencies are longer
2870 * than ~10 usec. We do use the stats for the relevant IO size
2871 * if available which does lead to better estimates.
2873 bucket
= blk_mq_poll_stats_bkt(rq
);
2877 if (q
->poll_stat
[bucket
].nr_samples
)
2878 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
2883 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2884 struct blk_mq_hw_ctx
*hctx
,
2887 struct hrtimer_sleeper hs
;
2888 enum hrtimer_mode mode
;
2892 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2898 * -1: don't ever hybrid sleep
2899 * 0: use half of prev avg
2900 * >0: use this specific value
2902 if (q
->poll_nsec
== -1)
2904 else if (q
->poll_nsec
> 0)
2905 nsecs
= q
->poll_nsec
;
2907 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2912 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2915 * This will be replaced with the stats tracking code, using
2916 * 'avg_completion_time / 2' as the pre-sleep target.
2920 mode
= HRTIMER_MODE_REL
;
2921 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2922 hrtimer_set_expires(&hs
.timer
, kt
);
2924 hrtimer_init_sleeper(&hs
, current
);
2926 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2928 set_current_state(TASK_UNINTERRUPTIBLE
);
2929 hrtimer_start_expires(&hs
.timer
, mode
);
2932 hrtimer_cancel(&hs
.timer
);
2933 mode
= HRTIMER_MODE_ABS
;
2934 } while (hs
.task
&& !signal_pending(current
));
2936 __set_current_state(TASK_RUNNING
);
2937 destroy_hrtimer_on_stack(&hs
.timer
);
2941 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2943 struct request_queue
*q
= hctx
->queue
;
2947 * If we sleep, have the caller restart the poll loop to reset
2948 * the state. Like for the other success return cases, the
2949 * caller is responsible for checking if the IO completed. If
2950 * the IO isn't complete, we'll get called again and will go
2951 * straight to the busy poll loop.
2953 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2956 hctx
->poll_considered
++;
2958 state
= current
->state
;
2959 while (!need_resched()) {
2962 hctx
->poll_invoked
++;
2964 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2966 hctx
->poll_success
++;
2967 set_current_state(TASK_RUNNING
);
2971 if (signal_pending_state(state
, current
))
2972 set_current_state(TASK_RUNNING
);
2974 if (current
->state
== TASK_RUNNING
)
2984 static bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2986 struct blk_mq_hw_ctx
*hctx
;
2989 if (!test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2992 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2993 if (!blk_qc_t_is_internal(cookie
))
2994 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2996 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2998 * With scheduling, if the request has completed, we'll
2999 * get a NULL return here, as we clear the sched tag when
3000 * that happens. The request still remains valid, like always,
3001 * so we should be safe with just the NULL check.
3007 return __blk_mq_poll(hctx
, rq
);
3010 static int __init
blk_mq_init(void)
3013 * See comment in block/blk.h rq_atomic_flags enum
3015 BUILD_BUG_ON((REQ_ATOM_STARTED
/ BITS_PER_BYTE
) !=
3016 (REQ_ATOM_COMPLETE
/ BITS_PER_BYTE
));
3018 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
3019 blk_mq_hctx_notify_dead
);
3022 subsys_initcall(blk_mq_init
);