1 // SPDX-License-Identifier: GPL-2.0
3 * Block multiqueue core code
5 * Copyright (C) 2013-2014 Jens Axboe
6 * Copyright (C) 2013-2014 Christoph Hellwig
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/backing-dev.h>
11 #include <linux/bio.h>
12 #include <linux/blkdev.h>
13 #include <linux/kmemleak.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/workqueue.h>
18 #include <linux/smp.h>
19 #include <linux/llist.h>
20 #include <linux/list_sort.h>
21 #include <linux/cpu.h>
22 #include <linux/cache.h>
23 #include <linux/sched/sysctl.h>
24 #include <linux/sched/topology.h>
25 #include <linux/sched/signal.h>
26 #include <linux/delay.h>
27 #include <linux/crash_dump.h>
28 #include <linux/prefetch.h>
30 #include <trace/events/block.h>
32 #include <linux/blk-mq.h>
33 #include <linux/t10-pi.h>
36 #include "blk-mq-debugfs.h"
37 #include "blk-mq-tag.h"
40 #include "blk-mq-sched.h"
41 #include "blk-rq-qos.h"
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
, sectors
, bucket
;
50 ddir
= rq_data_dir(rq
);
51 sectors
= blk_rq_stats_sectors(rq
);
53 bucket
= ddir
+ 2 * ilog2(sectors
);
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, dispatch list or elevator
65 * have pending work in this hardware queue.
67 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
69 return !list_empty_careful(&hctx
->dispatch
) ||
70 sbitmap_any_bit_set(&hctx
->ctx_map
) ||
71 blk_mq_sched_has_work(hctx
);
75 * Mark this ctx as having pending work in this hardware queue
77 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
78 struct blk_mq_ctx
*ctx
)
80 const int bit
= ctx
->index_hw
[hctx
->type
];
82 if (!sbitmap_test_bit(&hctx
->ctx_map
, bit
))
83 sbitmap_set_bit(&hctx
->ctx_map
, bit
);
86 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
87 struct blk_mq_ctx
*ctx
)
89 const int bit
= ctx
->index_hw
[hctx
->type
];
91 sbitmap_clear_bit(&hctx
->ctx_map
, bit
);
95 struct hd_struct
*part
;
96 unsigned int inflight
[2];
99 static bool blk_mq_check_inflight(struct blk_mq_hw_ctx
*hctx
,
100 struct request
*rq
, void *priv
,
103 struct mq_inflight
*mi
= priv
;
105 if (rq
->part
== mi
->part
)
106 mi
->inflight
[rq_data_dir(rq
)]++;
111 unsigned int blk_mq_in_flight(struct request_queue
*q
, struct hd_struct
*part
)
113 struct mq_inflight mi
= { .part
= part
};
115 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
117 return mi
.inflight
[0] + mi
.inflight
[1];
120 void blk_mq_in_flight_rw(struct request_queue
*q
, struct hd_struct
*part
,
121 unsigned int inflight
[2])
123 struct mq_inflight mi
= { .part
= part
};
125 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
126 inflight
[0] = mi
.inflight
[0];
127 inflight
[1] = mi
.inflight
[1];
130 void blk_freeze_queue_start(struct request_queue
*q
)
132 mutex_lock(&q
->mq_freeze_lock
);
133 if (++q
->mq_freeze_depth
== 1) {
134 percpu_ref_kill(&q
->q_usage_counter
);
135 mutex_unlock(&q
->mq_freeze_lock
);
137 blk_mq_run_hw_queues(q
, false);
139 mutex_unlock(&q
->mq_freeze_lock
);
142 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
144 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
146 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
148 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
150 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
151 unsigned long timeout
)
153 return wait_event_timeout(q
->mq_freeze_wq
,
154 percpu_ref_is_zero(&q
->q_usage_counter
),
157 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
160 * Guarantee no request is in use, so we can change any data structure of
161 * the queue afterward.
163 void blk_freeze_queue(struct request_queue
*q
)
166 * In the !blk_mq case we are only calling this to kill the
167 * q_usage_counter, otherwise this increases the freeze depth
168 * and waits for it to return to zero. For this reason there is
169 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
170 * exported to drivers as the only user for unfreeze is blk_mq.
172 blk_freeze_queue_start(q
);
173 blk_mq_freeze_queue_wait(q
);
176 void blk_mq_freeze_queue(struct request_queue
*q
)
179 * ...just an alias to keep freeze and unfreeze actions balanced
180 * in the blk_mq_* namespace
184 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
186 void blk_mq_unfreeze_queue(struct request_queue
*q
)
188 mutex_lock(&q
->mq_freeze_lock
);
189 q
->mq_freeze_depth
--;
190 WARN_ON_ONCE(q
->mq_freeze_depth
< 0);
191 if (!q
->mq_freeze_depth
) {
192 percpu_ref_resurrect(&q
->q_usage_counter
);
193 wake_up_all(&q
->mq_freeze_wq
);
195 mutex_unlock(&q
->mq_freeze_lock
);
197 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
200 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
201 * mpt3sas driver such that this function can be removed.
203 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
205 blk_queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
207 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
210 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
213 * Note: this function does not prevent that the struct request end_io()
214 * callback function is invoked. Once this function is returned, we make
215 * sure no dispatch can happen until the queue is unquiesced via
216 * blk_mq_unquiesce_queue().
218 void blk_mq_quiesce_queue(struct request_queue
*q
)
220 struct blk_mq_hw_ctx
*hctx
;
224 blk_mq_quiesce_queue_nowait(q
);
226 queue_for_each_hw_ctx(q
, hctx
, i
) {
227 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
228 synchronize_srcu(hctx
->srcu
);
235 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
238 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
241 * This function recovers queue into the state before quiescing
242 * which is done by blk_mq_quiesce_queue.
244 void blk_mq_unquiesce_queue(struct request_queue
*q
)
246 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
248 /* dispatch requests which are inserted during quiescing */
249 blk_mq_run_hw_queues(q
, true);
251 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
253 void blk_mq_wake_waiters(struct request_queue
*q
)
255 struct blk_mq_hw_ctx
*hctx
;
258 queue_for_each_hw_ctx(q
, hctx
, i
)
259 if (blk_mq_hw_queue_mapped(hctx
))
260 blk_mq_tag_wakeup_all(hctx
->tags
, true);
264 * Only need start/end time stamping if we have iostat or
265 * blk stats enabled, or using an IO scheduler.
267 static inline bool blk_mq_need_time_stamp(struct request
*rq
)
269 return (rq
->rq_flags
& (RQF_IO_STAT
| RQF_STATS
)) || rq
->q
->elevator
;
272 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
273 unsigned int tag
, unsigned int op
, u64 alloc_time_ns
)
275 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
276 struct request
*rq
= tags
->static_rqs
[tag
];
277 req_flags_t rq_flags
= 0;
279 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
281 rq
->internal_tag
= tag
;
283 if (data
->hctx
->flags
& BLK_MQ_F_TAG_SHARED
) {
284 rq_flags
= RQF_MQ_INFLIGHT
;
285 atomic_inc(&data
->hctx
->nr_active
);
288 rq
->internal_tag
= -1;
289 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
292 /* csd/requeue_work/fifo_time is initialized before use */
294 rq
->mq_ctx
= data
->ctx
;
295 rq
->mq_hctx
= data
->hctx
;
296 rq
->rq_flags
= rq_flags
;
298 if (data
->flags
& BLK_MQ_REQ_PREEMPT
)
299 rq
->rq_flags
|= RQF_PREEMPT
;
300 if (blk_queue_io_stat(data
->q
))
301 rq
->rq_flags
|= RQF_IO_STAT
;
302 INIT_LIST_HEAD(&rq
->queuelist
);
303 INIT_HLIST_NODE(&rq
->hash
);
304 RB_CLEAR_NODE(&rq
->rb_node
);
307 #ifdef CONFIG_BLK_RQ_ALLOC_TIME
308 rq
->alloc_time_ns
= alloc_time_ns
;
310 if (blk_mq_need_time_stamp(rq
))
311 rq
->start_time_ns
= ktime_get_ns();
313 rq
->start_time_ns
= 0;
314 rq
->io_start_time_ns
= 0;
315 rq
->stats_sectors
= 0;
316 rq
->nr_phys_segments
= 0;
317 #if defined(CONFIG_BLK_DEV_INTEGRITY)
318 rq
->nr_integrity_segments
= 0;
320 /* tag was already set */
322 WRITE_ONCE(rq
->deadline
, 0);
327 rq
->end_io_data
= NULL
;
329 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
330 refcount_set(&rq
->ref
, 1);
334 static struct request
*blk_mq_get_request(struct request_queue
*q
,
336 struct blk_mq_alloc_data
*data
)
338 struct elevator_queue
*e
= q
->elevator
;
341 bool clear_ctx_on_error
= false;
342 u64 alloc_time_ns
= 0;
344 blk_queue_enter_live(q
);
346 /* alloc_time includes depth and tag waits */
347 if (blk_queue_rq_alloc_time(q
))
348 alloc_time_ns
= ktime_get_ns();
351 if (likely(!data
->ctx
)) {
352 data
->ctx
= blk_mq_get_ctx(q
);
353 clear_ctx_on_error
= true;
355 if (likely(!data
->hctx
))
356 data
->hctx
= blk_mq_map_queue(q
, data
->cmd_flags
,
358 if (data
->cmd_flags
& REQ_NOWAIT
)
359 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
362 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
365 * Flush requests are special and go directly to the
366 * dispatch list. Don't include reserved tags in the
367 * limiting, as it isn't useful.
369 if (!op_is_flush(data
->cmd_flags
) &&
370 e
->type
->ops
.limit_depth
&&
371 !(data
->flags
& BLK_MQ_REQ_RESERVED
))
372 e
->type
->ops
.limit_depth(data
->cmd_flags
, data
);
374 blk_mq_tag_busy(data
->hctx
);
377 tag
= blk_mq_get_tag(data
);
378 if (tag
== BLK_MQ_TAG_FAIL
) {
379 if (clear_ctx_on_error
)
385 rq
= blk_mq_rq_ctx_init(data
, tag
, data
->cmd_flags
, alloc_time_ns
);
386 if (!op_is_flush(data
->cmd_flags
)) {
388 if (e
&& e
->type
->ops
.prepare_request
) {
389 if (e
->type
->icq_cache
)
390 blk_mq_sched_assign_ioc(rq
);
392 e
->type
->ops
.prepare_request(rq
, bio
);
393 rq
->rq_flags
|= RQF_ELVPRIV
;
396 data
->hctx
->queued
++;
400 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
401 blk_mq_req_flags_t flags
)
403 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
407 ret
= blk_queue_enter(q
, flags
);
411 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
415 return ERR_PTR(-EWOULDBLOCK
);
418 rq
->__sector
= (sector_t
) -1;
419 rq
->bio
= rq
->biotail
= NULL
;
422 EXPORT_SYMBOL(blk_mq_alloc_request
);
424 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
425 unsigned int op
, blk_mq_req_flags_t flags
, unsigned int hctx_idx
)
427 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
433 * If the tag allocator sleeps we could get an allocation for a
434 * different hardware context. No need to complicate the low level
435 * allocator for this for the rare use case of a command tied to
438 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
439 return ERR_PTR(-EINVAL
);
441 if (hctx_idx
>= q
->nr_hw_queues
)
442 return ERR_PTR(-EIO
);
444 ret
= blk_queue_enter(q
, flags
);
449 * Check if the hardware context is actually mapped to anything.
450 * If not tell the caller that it should skip this queue.
452 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
453 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
455 return ERR_PTR(-EXDEV
);
457 cpu
= cpumask_first_and(alloc_data
.hctx
->cpumask
, cpu_online_mask
);
458 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
460 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
464 return ERR_PTR(-EWOULDBLOCK
);
468 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
470 static void __blk_mq_free_request(struct request
*rq
)
472 struct request_queue
*q
= rq
->q
;
473 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
474 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
475 const int sched_tag
= rq
->internal_tag
;
477 blk_pm_mark_last_busy(rq
);
480 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
482 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
483 blk_mq_sched_restart(hctx
);
487 void blk_mq_free_request(struct request
*rq
)
489 struct request_queue
*q
= rq
->q
;
490 struct elevator_queue
*e
= q
->elevator
;
491 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
492 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
494 if (rq
->rq_flags
& RQF_ELVPRIV
) {
495 if (e
&& e
->type
->ops
.finish_request
)
496 e
->type
->ops
.finish_request(rq
);
498 put_io_context(rq
->elv
.icq
->ioc
);
503 ctx
->rq_completed
[rq_is_sync(rq
)]++;
504 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
505 atomic_dec(&hctx
->nr_active
);
507 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
508 laptop_io_completion(q
->backing_dev_info
);
512 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
513 if (refcount_dec_and_test(&rq
->ref
))
514 __blk_mq_free_request(rq
);
516 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
518 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
522 if (blk_mq_need_time_stamp(rq
))
523 now
= ktime_get_ns();
525 if (rq
->rq_flags
& RQF_STATS
) {
526 blk_mq_poll_stats_start(rq
->q
);
527 blk_stat_add(rq
, now
);
530 if (rq
->internal_tag
!= -1)
531 blk_mq_sched_completed_request(rq
, now
);
533 blk_account_io_done(rq
, now
);
536 rq_qos_done(rq
->q
, rq
);
537 rq
->end_io(rq
, error
);
539 blk_mq_free_request(rq
);
542 EXPORT_SYMBOL(__blk_mq_end_request
);
544 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
546 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
548 __blk_mq_end_request(rq
, error
);
550 EXPORT_SYMBOL(blk_mq_end_request
);
552 static void __blk_mq_complete_request_remote(void *data
)
554 struct request
*rq
= data
;
555 struct request_queue
*q
= rq
->q
;
557 q
->mq_ops
->complete(rq
);
560 static void __blk_mq_complete_request(struct request
*rq
)
562 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
563 struct request_queue
*q
= rq
->q
;
567 WRITE_ONCE(rq
->state
, MQ_RQ_COMPLETE
);
569 * Most of single queue controllers, there is only one irq vector
570 * for handling IO completion, and the only irq's affinity is set
571 * as all possible CPUs. On most of ARCHs, this affinity means the
572 * irq is handled on one specific CPU.
574 * So complete IO reqeust in softirq context in case of single queue
575 * for not degrading IO performance by irqsoff latency.
577 if (q
->nr_hw_queues
== 1) {
578 __blk_complete_request(rq
);
583 * For a polled request, always complete locallly, it's pointless
584 * to redirect the completion.
586 if ((rq
->cmd_flags
& REQ_HIPRI
) ||
587 !test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
)) {
588 q
->mq_ops
->complete(rq
);
593 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &q
->queue_flags
))
594 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
596 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
597 rq
->csd
.func
= __blk_mq_complete_request_remote
;
600 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
602 q
->mq_ops
->complete(rq
);
607 static void hctx_unlock(struct blk_mq_hw_ctx
*hctx
, int srcu_idx
)
608 __releases(hctx
->srcu
)
610 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
))
613 srcu_read_unlock(hctx
->srcu
, srcu_idx
);
616 static void hctx_lock(struct blk_mq_hw_ctx
*hctx
, int *srcu_idx
)
617 __acquires(hctx
->srcu
)
619 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
620 /* shut up gcc false positive */
624 *srcu_idx
= srcu_read_lock(hctx
->srcu
);
628 * blk_mq_complete_request - end I/O on a request
629 * @rq: the request being processed
632 * Ends all I/O on a request. It does not handle partial completions.
633 * The actual completion happens out-of-order, through a IPI handler.
635 bool blk_mq_complete_request(struct request
*rq
)
637 if (unlikely(blk_should_fake_timeout(rq
->q
)))
639 __blk_mq_complete_request(rq
);
642 EXPORT_SYMBOL(blk_mq_complete_request
);
644 void blk_mq_start_request(struct request
*rq
)
646 struct request_queue
*q
= rq
->q
;
648 trace_block_rq_issue(q
, rq
);
650 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
651 rq
->io_start_time_ns
= ktime_get_ns();
652 rq
->stats_sectors
= blk_rq_sectors(rq
);
653 rq
->rq_flags
|= RQF_STATS
;
657 WARN_ON_ONCE(blk_mq_rq_state(rq
) != MQ_RQ_IDLE
);
660 WRITE_ONCE(rq
->state
, MQ_RQ_IN_FLIGHT
);
662 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
664 * Make sure space for the drain appears. We know we can do
665 * this because max_hw_segments has been adjusted to be one
666 * fewer than the device can handle.
668 rq
->nr_phys_segments
++;
671 #ifdef CONFIG_BLK_DEV_INTEGRITY
672 if (blk_integrity_rq(rq
) && req_op(rq
) == REQ_OP_WRITE
)
673 q
->integrity
.profile
->prepare_fn(rq
);
676 EXPORT_SYMBOL(blk_mq_start_request
);
678 static void __blk_mq_requeue_request(struct request
*rq
)
680 struct request_queue
*q
= rq
->q
;
682 blk_mq_put_driver_tag(rq
);
684 trace_block_rq_requeue(q
, rq
);
685 rq_qos_requeue(q
, rq
);
687 if (blk_mq_request_started(rq
)) {
688 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
689 rq
->rq_flags
&= ~RQF_TIMED_OUT
;
690 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
691 rq
->nr_phys_segments
--;
695 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
697 __blk_mq_requeue_request(rq
);
699 /* this request will be re-inserted to io scheduler queue */
700 blk_mq_sched_requeue_request(rq
);
702 BUG_ON(!list_empty(&rq
->queuelist
));
703 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
705 EXPORT_SYMBOL(blk_mq_requeue_request
);
707 static void blk_mq_requeue_work(struct work_struct
*work
)
709 struct request_queue
*q
=
710 container_of(work
, struct request_queue
, requeue_work
.work
);
712 struct request
*rq
, *next
;
714 spin_lock_irq(&q
->requeue_lock
);
715 list_splice_init(&q
->requeue_list
, &rq_list
);
716 spin_unlock_irq(&q
->requeue_lock
);
718 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
719 if (!(rq
->rq_flags
& (RQF_SOFTBARRIER
| RQF_DONTPREP
)))
722 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
723 list_del_init(&rq
->queuelist
);
725 * If RQF_DONTPREP, rq has contained some driver specific
726 * data, so insert it to hctx dispatch list to avoid any
729 if (rq
->rq_flags
& RQF_DONTPREP
)
730 blk_mq_request_bypass_insert(rq
, false);
732 blk_mq_sched_insert_request(rq
, true, false, false);
735 while (!list_empty(&rq_list
)) {
736 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
737 list_del_init(&rq
->queuelist
);
738 blk_mq_sched_insert_request(rq
, false, false, false);
741 blk_mq_run_hw_queues(q
, false);
744 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
745 bool kick_requeue_list
)
747 struct request_queue
*q
= rq
->q
;
751 * We abuse this flag that is otherwise used by the I/O scheduler to
752 * request head insertion from the workqueue.
754 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
756 spin_lock_irqsave(&q
->requeue_lock
, flags
);
758 rq
->rq_flags
|= RQF_SOFTBARRIER
;
759 list_add(&rq
->queuelist
, &q
->requeue_list
);
761 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
763 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
765 if (kick_requeue_list
)
766 blk_mq_kick_requeue_list(q
);
769 void blk_mq_kick_requeue_list(struct request_queue
*q
)
771 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
, 0);
773 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
775 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
778 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
779 msecs_to_jiffies(msecs
));
781 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
783 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
785 if (tag
< tags
->nr_tags
) {
786 prefetch(tags
->rqs
[tag
]);
787 return tags
->rqs
[tag
];
792 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
794 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
795 void *priv
, bool reserved
)
798 * If we find a request that is inflight and the queue matches,
799 * we know the queue is busy. Return false to stop the iteration.
801 if (rq
->state
== MQ_RQ_IN_FLIGHT
&& rq
->q
== hctx
->queue
) {
811 bool blk_mq_queue_inflight(struct request_queue
*q
)
815 blk_mq_queue_tag_busy_iter(q
, blk_mq_rq_inflight
, &busy
);
818 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight
);
820 static void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
822 req
->rq_flags
|= RQF_TIMED_OUT
;
823 if (req
->q
->mq_ops
->timeout
) {
824 enum blk_eh_timer_return ret
;
826 ret
= req
->q
->mq_ops
->timeout(req
, reserved
);
827 if (ret
== BLK_EH_DONE
)
829 WARN_ON_ONCE(ret
!= BLK_EH_RESET_TIMER
);
835 static bool blk_mq_req_expired(struct request
*rq
, unsigned long *next
)
837 unsigned long deadline
;
839 if (blk_mq_rq_state(rq
) != MQ_RQ_IN_FLIGHT
)
841 if (rq
->rq_flags
& RQF_TIMED_OUT
)
844 deadline
= READ_ONCE(rq
->deadline
);
845 if (time_after_eq(jiffies
, deadline
))
850 else if (time_after(*next
, deadline
))
855 static bool blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
856 struct request
*rq
, void *priv
, bool reserved
)
858 unsigned long *next
= priv
;
861 * Just do a quick check if it is expired before locking the request in
862 * so we're not unnecessarilly synchronizing across CPUs.
864 if (!blk_mq_req_expired(rq
, next
))
868 * We have reason to believe the request may be expired. Take a
869 * reference on the request to lock this request lifetime into its
870 * currently allocated context to prevent it from being reallocated in
871 * the event the completion by-passes this timeout handler.
873 * If the reference was already released, then the driver beat the
874 * timeout handler to posting a natural completion.
876 if (!refcount_inc_not_zero(&rq
->ref
))
880 * The request is now locked and cannot be reallocated underneath the
881 * timeout handler's processing. Re-verify this exact request is truly
882 * expired; if it is not expired, then the request was completed and
883 * reallocated as a new request.
885 if (blk_mq_req_expired(rq
, next
))
886 blk_mq_rq_timed_out(rq
, reserved
);
888 if (is_flush_rq(rq
, hctx
))
890 else if (refcount_dec_and_test(&rq
->ref
))
891 __blk_mq_free_request(rq
);
896 static void blk_mq_timeout_work(struct work_struct
*work
)
898 struct request_queue
*q
=
899 container_of(work
, struct request_queue
, timeout_work
);
900 unsigned long next
= 0;
901 struct blk_mq_hw_ctx
*hctx
;
904 /* A deadlock might occur if a request is stuck requiring a
905 * timeout at the same time a queue freeze is waiting
906 * completion, since the timeout code would not be able to
907 * acquire the queue reference here.
909 * That's why we don't use blk_queue_enter here; instead, we use
910 * percpu_ref_tryget directly, because we need to be able to
911 * obtain a reference even in the short window between the queue
912 * starting to freeze, by dropping the first reference in
913 * blk_freeze_queue_start, and the moment the last request is
914 * consumed, marked by the instant q_usage_counter reaches
917 if (!percpu_ref_tryget(&q
->q_usage_counter
))
920 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &next
);
923 mod_timer(&q
->timeout
, next
);
926 * Request timeouts are handled as a forward rolling timer. If
927 * we end up here it means that no requests are pending and
928 * also that no request has been pending for a while. Mark
931 queue_for_each_hw_ctx(q
, hctx
, i
) {
932 /* the hctx may be unmapped, so check it here */
933 if (blk_mq_hw_queue_mapped(hctx
))
934 blk_mq_tag_idle(hctx
);
940 struct flush_busy_ctx_data
{
941 struct blk_mq_hw_ctx
*hctx
;
942 struct list_head
*list
;
945 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
947 struct flush_busy_ctx_data
*flush_data
= data
;
948 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
949 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
950 enum hctx_type type
= hctx
->type
;
952 spin_lock(&ctx
->lock
);
953 list_splice_tail_init(&ctx
->rq_lists
[type
], flush_data
->list
);
954 sbitmap_clear_bit(sb
, bitnr
);
955 spin_unlock(&ctx
->lock
);
960 * Process software queues that have been marked busy, splicing them
961 * to the for-dispatch
963 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
965 struct flush_busy_ctx_data data
= {
970 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
972 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
974 struct dispatch_rq_data
{
975 struct blk_mq_hw_ctx
*hctx
;
979 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
982 struct dispatch_rq_data
*dispatch_data
= data
;
983 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
984 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
985 enum hctx_type type
= hctx
->type
;
987 spin_lock(&ctx
->lock
);
988 if (!list_empty(&ctx
->rq_lists
[type
])) {
989 dispatch_data
->rq
= list_entry_rq(ctx
->rq_lists
[type
].next
);
990 list_del_init(&dispatch_data
->rq
->queuelist
);
991 if (list_empty(&ctx
->rq_lists
[type
]))
992 sbitmap_clear_bit(sb
, bitnr
);
994 spin_unlock(&ctx
->lock
);
996 return !dispatch_data
->rq
;
999 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
1000 struct blk_mq_ctx
*start
)
1002 unsigned off
= start
? start
->index_hw
[hctx
->type
] : 0;
1003 struct dispatch_rq_data data
= {
1008 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
1009 dispatch_rq_from_ctx
, &data
);
1014 static inline unsigned int queued_to_index(unsigned int queued
)
1019 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
1022 bool blk_mq_get_driver_tag(struct request
*rq
)
1024 struct blk_mq_alloc_data data
= {
1026 .hctx
= rq
->mq_hctx
,
1027 .flags
= BLK_MQ_REQ_NOWAIT
,
1028 .cmd_flags
= rq
->cmd_flags
,
1035 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
1036 data
.flags
|= BLK_MQ_REQ_RESERVED
;
1038 shared
= blk_mq_tag_busy(data
.hctx
);
1039 rq
->tag
= blk_mq_get_tag(&data
);
1042 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
1043 atomic_inc(&data
.hctx
->nr_active
);
1045 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
1048 return rq
->tag
!= -1;
1051 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
,
1052 int flags
, void *key
)
1054 struct blk_mq_hw_ctx
*hctx
;
1056 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1058 spin_lock(&hctx
->dispatch_wait_lock
);
1059 if (!list_empty(&wait
->entry
)) {
1060 struct sbitmap_queue
*sbq
;
1062 list_del_init(&wait
->entry
);
1063 sbq
= &hctx
->tags
->bitmap_tags
;
1064 atomic_dec(&sbq
->ws_active
);
1066 spin_unlock(&hctx
->dispatch_wait_lock
);
1068 blk_mq_run_hw_queue(hctx
, true);
1073 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1074 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1075 * restart. For both cases, take care to check the condition again after
1076 * marking us as waiting.
1078 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx
*hctx
,
1081 struct sbitmap_queue
*sbq
= &hctx
->tags
->bitmap_tags
;
1082 struct wait_queue_head
*wq
;
1083 wait_queue_entry_t
*wait
;
1086 if (!(hctx
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1087 blk_mq_sched_mark_restart_hctx(hctx
);
1090 * It's possible that a tag was freed in the window between the
1091 * allocation failure and adding the hardware queue to the wait
1094 * Don't clear RESTART here, someone else could have set it.
1095 * At most this will cost an extra queue run.
1097 return blk_mq_get_driver_tag(rq
);
1100 wait
= &hctx
->dispatch_wait
;
1101 if (!list_empty_careful(&wait
->entry
))
1104 wq
= &bt_wait_ptr(sbq
, hctx
)->wait
;
1106 spin_lock_irq(&wq
->lock
);
1107 spin_lock(&hctx
->dispatch_wait_lock
);
1108 if (!list_empty(&wait
->entry
)) {
1109 spin_unlock(&hctx
->dispatch_wait_lock
);
1110 spin_unlock_irq(&wq
->lock
);
1114 atomic_inc(&sbq
->ws_active
);
1115 wait
->flags
&= ~WQ_FLAG_EXCLUSIVE
;
1116 __add_wait_queue(wq
, wait
);
1119 * It's possible that a tag was freed in the window between the
1120 * allocation failure and adding the hardware queue to the wait
1123 ret
= blk_mq_get_driver_tag(rq
);
1125 spin_unlock(&hctx
->dispatch_wait_lock
);
1126 spin_unlock_irq(&wq
->lock
);
1131 * We got a tag, remove ourselves from the wait queue to ensure
1132 * someone else gets the wakeup.
1134 list_del_init(&wait
->entry
);
1135 atomic_dec(&sbq
->ws_active
);
1136 spin_unlock(&hctx
->dispatch_wait_lock
);
1137 spin_unlock_irq(&wq
->lock
);
1142 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1143 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1145 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1146 * - EWMA is one simple way to compute running average value
1147 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1148 * - take 4 as factor for avoiding to get too small(0) result, and this
1149 * factor doesn't matter because EWMA decreases exponentially
1151 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx
*hctx
, bool busy
)
1155 if (hctx
->queue
->elevator
)
1158 ewma
= hctx
->dispatch_busy
;
1163 ewma
*= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
- 1;
1165 ewma
+= 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR
;
1166 ewma
/= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
;
1168 hctx
->dispatch_busy
= ewma
;
1171 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1174 * Returns true if we did some work AND can potentially do more.
1176 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
,
1179 struct blk_mq_hw_ctx
*hctx
;
1180 struct request
*rq
, *nxt
;
1181 bool no_tag
= false;
1183 blk_status_t ret
= BLK_STS_OK
;
1185 if (list_empty(list
))
1188 WARN_ON(!list_is_singular(list
) && got_budget
);
1191 * Now process all the entries, sending them to the driver.
1193 errors
= queued
= 0;
1195 struct blk_mq_queue_data bd
;
1197 rq
= list_first_entry(list
, struct request
, queuelist
);
1200 if (!got_budget
&& !blk_mq_get_dispatch_budget(hctx
))
1203 if (!blk_mq_get_driver_tag(rq
)) {
1205 * The initial allocation attempt failed, so we need to
1206 * rerun the hardware queue when a tag is freed. The
1207 * waitqueue takes care of that. If the queue is run
1208 * before we add this entry back on the dispatch list,
1209 * we'll re-run it below.
1211 if (!blk_mq_mark_tag_wait(hctx
, rq
)) {
1212 blk_mq_put_dispatch_budget(hctx
);
1214 * For non-shared tags, the RESTART check
1217 if (hctx
->flags
& BLK_MQ_F_TAG_SHARED
)
1223 list_del_init(&rq
->queuelist
);
1228 * Flag last if we have no more requests, or if we have more
1229 * but can't assign a driver tag to it.
1231 if (list_empty(list
))
1234 nxt
= list_first_entry(list
, struct request
, queuelist
);
1235 bd
.last
= !blk_mq_get_driver_tag(nxt
);
1238 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1239 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
) {
1241 * If an I/O scheduler has been configured and we got a
1242 * driver tag for the next request already, free it
1245 if (!list_empty(list
)) {
1246 nxt
= list_first_entry(list
, struct request
, queuelist
);
1247 blk_mq_put_driver_tag(nxt
);
1249 list_add(&rq
->queuelist
, list
);
1250 __blk_mq_requeue_request(rq
);
1254 if (unlikely(ret
!= BLK_STS_OK
)) {
1256 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1261 } while (!list_empty(list
));
1263 hctx
->dispatched
[queued_to_index(queued
)]++;
1266 * Any items that need requeuing? Stuff them into hctx->dispatch,
1267 * that is where we will continue on next queue run.
1269 if (!list_empty(list
)) {
1273 * If we didn't flush the entire list, we could have told
1274 * the driver there was more coming, but that turned out to
1277 if (q
->mq_ops
->commit_rqs
)
1278 q
->mq_ops
->commit_rqs(hctx
);
1280 spin_lock(&hctx
->lock
);
1281 list_splice_init(list
, &hctx
->dispatch
);
1282 spin_unlock(&hctx
->lock
);
1285 * If SCHED_RESTART was set by the caller of this function and
1286 * it is no longer set that means that it was cleared by another
1287 * thread and hence that a queue rerun is needed.
1289 * If 'no_tag' is set, that means that we failed getting
1290 * a driver tag with an I/O scheduler attached. If our dispatch
1291 * waitqueue is no longer active, ensure that we run the queue
1292 * AFTER adding our entries back to the list.
1294 * If no I/O scheduler has been configured it is possible that
1295 * the hardware queue got stopped and restarted before requests
1296 * were pushed back onto the dispatch list. Rerun the queue to
1297 * avoid starvation. Notes:
1298 * - blk_mq_run_hw_queue() checks whether or not a queue has
1299 * been stopped before rerunning a queue.
1300 * - Some but not all block drivers stop a queue before
1301 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1304 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1305 * bit is set, run queue after a delay to avoid IO stalls
1306 * that could otherwise occur if the queue is idle.
1308 needs_restart
= blk_mq_sched_needs_restart(hctx
);
1309 if (!needs_restart
||
1310 (no_tag
&& list_empty_careful(&hctx
->dispatch_wait
.entry
)))
1311 blk_mq_run_hw_queue(hctx
, true);
1312 else if (needs_restart
&& (ret
== BLK_STS_RESOURCE
))
1313 blk_mq_delay_run_hw_queue(hctx
, BLK_MQ_RESOURCE_DELAY
);
1315 blk_mq_update_dispatch_busy(hctx
, true);
1318 blk_mq_update_dispatch_busy(hctx
, false);
1321 * If the host/device is unable to accept more work, inform the
1324 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1327 return (queued
+ errors
) != 0;
1330 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1335 * We should be running this queue from one of the CPUs that
1338 * There are at least two related races now between setting
1339 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1340 * __blk_mq_run_hw_queue():
1342 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1343 * but later it becomes online, then this warning is harmless
1346 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1347 * but later it becomes offline, then the warning can't be
1348 * triggered, and we depend on blk-mq timeout handler to
1349 * handle dispatched requests to this hctx
1351 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1352 cpu_online(hctx
->next_cpu
)) {
1353 printk(KERN_WARNING
"run queue from wrong CPU %d, hctx %s\n",
1354 raw_smp_processor_id(),
1355 cpumask_empty(hctx
->cpumask
) ? "inactive": "active");
1360 * We can't run the queue inline with ints disabled. Ensure that
1361 * we catch bad users of this early.
1363 WARN_ON_ONCE(in_interrupt());
1365 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1367 hctx_lock(hctx
, &srcu_idx
);
1368 blk_mq_sched_dispatch_requests(hctx
);
1369 hctx_unlock(hctx
, srcu_idx
);
1372 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx
*hctx
)
1374 int cpu
= cpumask_first_and(hctx
->cpumask
, cpu_online_mask
);
1376 if (cpu
>= nr_cpu_ids
)
1377 cpu
= cpumask_first(hctx
->cpumask
);
1382 * It'd be great if the workqueue API had a way to pass
1383 * in a mask and had some smarts for more clever placement.
1384 * For now we just round-robin here, switching for every
1385 * BLK_MQ_CPU_WORK_BATCH queued items.
1387 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1390 int next_cpu
= hctx
->next_cpu
;
1392 if (hctx
->queue
->nr_hw_queues
== 1)
1393 return WORK_CPU_UNBOUND
;
1395 if (--hctx
->next_cpu_batch
<= 0) {
1397 next_cpu
= cpumask_next_and(next_cpu
, hctx
->cpumask
,
1399 if (next_cpu
>= nr_cpu_ids
)
1400 next_cpu
= blk_mq_first_mapped_cpu(hctx
);
1401 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1405 * Do unbound schedule if we can't find a online CPU for this hctx,
1406 * and it should only happen in the path of handling CPU DEAD.
1408 if (!cpu_online(next_cpu
)) {
1415 * Make sure to re-select CPU next time once after CPUs
1416 * in hctx->cpumask become online again.
1418 hctx
->next_cpu
= next_cpu
;
1419 hctx
->next_cpu_batch
= 1;
1420 return WORK_CPU_UNBOUND
;
1423 hctx
->next_cpu
= next_cpu
;
1427 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1428 unsigned long msecs
)
1430 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1433 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1434 int cpu
= get_cpu();
1435 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1436 __blk_mq_run_hw_queue(hctx
);
1444 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
,
1445 msecs_to_jiffies(msecs
));
1448 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1450 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1452 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1454 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1460 * When queue is quiesced, we may be switching io scheduler, or
1461 * updating nr_hw_queues, or other things, and we can't run queue
1462 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1464 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1467 hctx_lock(hctx
, &srcu_idx
);
1468 need_run
= !blk_queue_quiesced(hctx
->queue
) &&
1469 blk_mq_hctx_has_pending(hctx
);
1470 hctx_unlock(hctx
, srcu_idx
);
1473 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1475 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1477 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1479 struct blk_mq_hw_ctx
*hctx
;
1482 queue_for_each_hw_ctx(q
, hctx
, i
) {
1483 if (blk_mq_hctx_stopped(hctx
))
1486 blk_mq_run_hw_queue(hctx
, async
);
1489 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1492 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1493 * @q: request queue.
1495 * The caller is responsible for serializing this function against
1496 * blk_mq_{start,stop}_hw_queue().
1498 bool blk_mq_queue_stopped(struct request_queue
*q
)
1500 struct blk_mq_hw_ctx
*hctx
;
1503 queue_for_each_hw_ctx(q
, hctx
, i
)
1504 if (blk_mq_hctx_stopped(hctx
))
1509 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1512 * This function is often used for pausing .queue_rq() by driver when
1513 * there isn't enough resource or some conditions aren't satisfied, and
1514 * BLK_STS_RESOURCE is usually returned.
1516 * We do not guarantee that dispatch can be drained or blocked
1517 * after blk_mq_stop_hw_queue() returns. Please use
1518 * blk_mq_quiesce_queue() for that requirement.
1520 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1522 cancel_delayed_work(&hctx
->run_work
);
1524 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1526 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1529 * This function is often used for pausing .queue_rq() by driver when
1530 * there isn't enough resource or some conditions aren't satisfied, and
1531 * BLK_STS_RESOURCE is usually returned.
1533 * We do not guarantee that dispatch can be drained or blocked
1534 * after blk_mq_stop_hw_queues() returns. Please use
1535 * blk_mq_quiesce_queue() for that requirement.
1537 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1539 struct blk_mq_hw_ctx
*hctx
;
1542 queue_for_each_hw_ctx(q
, hctx
, i
)
1543 blk_mq_stop_hw_queue(hctx
);
1545 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1547 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1549 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1551 blk_mq_run_hw_queue(hctx
, false);
1553 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1555 void blk_mq_start_hw_queues(struct request_queue
*q
)
1557 struct blk_mq_hw_ctx
*hctx
;
1560 queue_for_each_hw_ctx(q
, hctx
, i
)
1561 blk_mq_start_hw_queue(hctx
);
1563 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1565 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1567 if (!blk_mq_hctx_stopped(hctx
))
1570 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1571 blk_mq_run_hw_queue(hctx
, async
);
1573 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1575 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1577 struct blk_mq_hw_ctx
*hctx
;
1580 queue_for_each_hw_ctx(q
, hctx
, i
)
1581 blk_mq_start_stopped_hw_queue(hctx
, async
);
1583 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1585 static void blk_mq_run_work_fn(struct work_struct
*work
)
1587 struct blk_mq_hw_ctx
*hctx
;
1589 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1592 * If we are stopped, don't run the queue.
1594 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1597 __blk_mq_run_hw_queue(hctx
);
1600 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1604 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1605 enum hctx_type type
= hctx
->type
;
1607 lockdep_assert_held(&ctx
->lock
);
1609 trace_block_rq_insert(hctx
->queue
, rq
);
1612 list_add(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1614 list_add_tail(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1617 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1620 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1622 lockdep_assert_held(&ctx
->lock
);
1624 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1625 blk_mq_hctx_mark_pending(hctx
, ctx
);
1629 * Should only be used carefully, when the caller knows we want to
1630 * bypass a potential IO scheduler on the target device.
1632 void blk_mq_request_bypass_insert(struct request
*rq
, bool run_queue
)
1634 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1636 spin_lock(&hctx
->lock
);
1637 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1638 spin_unlock(&hctx
->lock
);
1641 blk_mq_run_hw_queue(hctx
, false);
1644 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1645 struct list_head
*list
)
1649 enum hctx_type type
= hctx
->type
;
1652 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1655 list_for_each_entry(rq
, list
, queuelist
) {
1656 BUG_ON(rq
->mq_ctx
!= ctx
);
1657 trace_block_rq_insert(hctx
->queue
, rq
);
1660 spin_lock(&ctx
->lock
);
1661 list_splice_tail_init(list
, &ctx
->rq_lists
[type
]);
1662 blk_mq_hctx_mark_pending(hctx
, ctx
);
1663 spin_unlock(&ctx
->lock
);
1666 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1668 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1669 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1671 if (rqa
->mq_ctx
< rqb
->mq_ctx
)
1673 else if (rqa
->mq_ctx
> rqb
->mq_ctx
)
1675 else if (rqa
->mq_hctx
< rqb
->mq_hctx
)
1677 else if (rqa
->mq_hctx
> rqb
->mq_hctx
)
1680 return blk_rq_pos(rqa
) > blk_rq_pos(rqb
);
1683 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1685 struct blk_mq_hw_ctx
*this_hctx
;
1686 struct blk_mq_ctx
*this_ctx
;
1687 struct request_queue
*this_q
;
1693 list_splice_init(&plug
->mq_list
, &list
);
1695 if (plug
->rq_count
> 2 && plug
->multiple_queues
)
1696 list_sort(NULL
, &list
, plug_rq_cmp
);
1705 while (!list_empty(&list
)) {
1706 rq
= list_entry_rq(list
.next
);
1707 list_del_init(&rq
->queuelist
);
1709 if (rq
->mq_hctx
!= this_hctx
|| rq
->mq_ctx
!= this_ctx
) {
1711 trace_block_unplug(this_q
, depth
, !from_schedule
);
1712 blk_mq_sched_insert_requests(this_hctx
, this_ctx
,
1718 this_ctx
= rq
->mq_ctx
;
1719 this_hctx
= rq
->mq_hctx
;
1724 list_add_tail(&rq
->queuelist
, &rq_list
);
1728 * If 'this_hctx' is set, we know we have entries to complete
1729 * on 'rq_list'. Do those.
1732 trace_block_unplug(this_q
, depth
, !from_schedule
);
1733 blk_mq_sched_insert_requests(this_hctx
, this_ctx
, &rq_list
,
1738 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
,
1739 unsigned int nr_segs
)
1741 if (bio
->bi_opf
& REQ_RAHEAD
)
1742 rq
->cmd_flags
|= REQ_FAILFAST_MASK
;
1744 rq
->__sector
= bio
->bi_iter
.bi_sector
;
1745 rq
->write_hint
= bio
->bi_write_hint
;
1746 blk_rq_bio_prep(rq
, bio
, nr_segs
);
1748 blk_account_io_start(rq
, true);
1751 static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1753 blk_qc_t
*cookie
, bool last
)
1755 struct request_queue
*q
= rq
->q
;
1756 struct blk_mq_queue_data bd
= {
1760 blk_qc_t new_cookie
;
1763 new_cookie
= request_to_qc_t(hctx
, rq
);
1766 * For OK queue, we are done. For error, caller may kill it.
1767 * Any other error (busy), just add it to our list as we
1768 * previously would have done.
1770 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1773 blk_mq_update_dispatch_busy(hctx
, false);
1774 *cookie
= new_cookie
;
1776 case BLK_STS_RESOURCE
:
1777 case BLK_STS_DEV_RESOURCE
:
1778 blk_mq_update_dispatch_busy(hctx
, true);
1779 __blk_mq_requeue_request(rq
);
1782 blk_mq_update_dispatch_busy(hctx
, false);
1783 *cookie
= BLK_QC_T_NONE
;
1790 static blk_status_t
__blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1793 bool bypass_insert
, bool last
)
1795 struct request_queue
*q
= rq
->q
;
1796 bool run_queue
= true;
1799 * RCU or SRCU read lock is needed before checking quiesced flag.
1801 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1802 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1803 * and avoid driver to try to dispatch again.
1805 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1807 bypass_insert
= false;
1811 if (q
->elevator
&& !bypass_insert
)
1814 if (!blk_mq_get_dispatch_budget(hctx
))
1817 if (!blk_mq_get_driver_tag(rq
)) {
1818 blk_mq_put_dispatch_budget(hctx
);
1822 return __blk_mq_issue_directly(hctx
, rq
, cookie
, last
);
1825 return BLK_STS_RESOURCE
;
1827 blk_mq_request_bypass_insert(rq
, run_queue
);
1831 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1832 struct request
*rq
, blk_qc_t
*cookie
)
1837 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1839 hctx_lock(hctx
, &srcu_idx
);
1841 ret
= __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false, true);
1842 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1843 blk_mq_request_bypass_insert(rq
, true);
1844 else if (ret
!= BLK_STS_OK
)
1845 blk_mq_end_request(rq
, ret
);
1847 hctx_unlock(hctx
, srcu_idx
);
1850 blk_status_t
blk_mq_request_issue_directly(struct request
*rq
, bool last
)
1854 blk_qc_t unused_cookie
;
1855 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1857 hctx_lock(hctx
, &srcu_idx
);
1858 ret
= __blk_mq_try_issue_directly(hctx
, rq
, &unused_cookie
, true, last
);
1859 hctx_unlock(hctx
, srcu_idx
);
1864 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx
*hctx
,
1865 struct list_head
*list
)
1867 while (!list_empty(list
)) {
1869 struct request
*rq
= list_first_entry(list
, struct request
,
1872 list_del_init(&rq
->queuelist
);
1873 ret
= blk_mq_request_issue_directly(rq
, list_empty(list
));
1874 if (ret
!= BLK_STS_OK
) {
1875 if (ret
== BLK_STS_RESOURCE
||
1876 ret
== BLK_STS_DEV_RESOURCE
) {
1877 blk_mq_request_bypass_insert(rq
,
1881 blk_mq_end_request(rq
, ret
);
1886 * If we didn't flush the entire list, we could have told
1887 * the driver there was more coming, but that turned out to
1890 if (!list_empty(list
) && hctx
->queue
->mq_ops
->commit_rqs
)
1891 hctx
->queue
->mq_ops
->commit_rqs(hctx
);
1894 static void blk_add_rq_to_plug(struct blk_plug
*plug
, struct request
*rq
)
1896 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1898 if (!plug
->multiple_queues
&& !list_is_singular(&plug
->mq_list
)) {
1899 struct request
*tmp
;
1901 tmp
= list_first_entry(&plug
->mq_list
, struct request
,
1903 if (tmp
->q
!= rq
->q
)
1904 plug
->multiple_queues
= true;
1908 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1910 const int is_sync
= op_is_sync(bio
->bi_opf
);
1911 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1912 struct blk_mq_alloc_data data
= { .flags
= 0};
1914 struct blk_plug
*plug
;
1915 struct request
*same_queue_rq
= NULL
;
1916 unsigned int nr_segs
;
1919 blk_queue_bounce(q
, &bio
);
1920 __blk_queue_split(q
, &bio
, &nr_segs
);
1922 if (!bio_integrity_prep(bio
))
1923 return BLK_QC_T_NONE
;
1925 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1926 blk_attempt_plug_merge(q
, bio
, nr_segs
, &same_queue_rq
))
1927 return BLK_QC_T_NONE
;
1929 if (blk_mq_sched_bio_merge(q
, bio
, nr_segs
))
1930 return BLK_QC_T_NONE
;
1932 rq_qos_throttle(q
, bio
);
1934 data
.cmd_flags
= bio
->bi_opf
;
1935 rq
= blk_mq_get_request(q
, bio
, &data
);
1936 if (unlikely(!rq
)) {
1937 rq_qos_cleanup(q
, bio
);
1938 if (bio
->bi_opf
& REQ_NOWAIT
)
1939 bio_wouldblock_error(bio
);
1940 return BLK_QC_T_NONE
;
1943 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1945 rq_qos_track(q
, rq
, bio
);
1947 cookie
= request_to_qc_t(data
.hctx
, rq
);
1949 blk_mq_bio_to_request(rq
, bio
, nr_segs
);
1951 plug
= blk_mq_plug(q
, bio
);
1952 if (unlikely(is_flush_fua
)) {
1953 /* bypass scheduler for flush rq */
1954 blk_insert_flush(rq
);
1955 blk_mq_run_hw_queue(data
.hctx
, true);
1956 } else if (plug
&& (q
->nr_hw_queues
== 1 || q
->mq_ops
->commit_rqs
||
1957 !blk_queue_nonrot(q
))) {
1959 * Use plugging if we have a ->commit_rqs() hook as well, as
1960 * we know the driver uses bd->last in a smart fashion.
1962 * Use normal plugging if this disk is slow HDD, as sequential
1963 * IO may benefit a lot from plug merging.
1965 unsigned int request_count
= plug
->rq_count
;
1966 struct request
*last
= NULL
;
1969 trace_block_plug(q
);
1971 last
= list_entry_rq(plug
->mq_list
.prev
);
1973 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1974 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1975 blk_flush_plug_list(plug
, false);
1976 trace_block_plug(q
);
1979 blk_add_rq_to_plug(plug
, rq
);
1980 } else if (q
->elevator
) {
1981 blk_mq_sched_insert_request(rq
, false, true, true);
1982 } else if (plug
&& !blk_queue_nomerges(q
)) {
1984 * We do limited plugging. If the bio can be merged, do that.
1985 * Otherwise the existing request in the plug list will be
1986 * issued. So the plug list will have one request at most
1987 * The plug list might get flushed before this. If that happens,
1988 * the plug list is empty, and same_queue_rq is invalid.
1990 if (list_empty(&plug
->mq_list
))
1991 same_queue_rq
= NULL
;
1992 if (same_queue_rq
) {
1993 list_del_init(&same_queue_rq
->queuelist
);
1996 blk_add_rq_to_plug(plug
, rq
);
1997 trace_block_plug(q
);
1999 if (same_queue_rq
) {
2000 data
.hctx
= same_queue_rq
->mq_hctx
;
2001 trace_block_unplug(q
, 1, true);
2002 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
2005 } else if ((q
->nr_hw_queues
> 1 && is_sync
) ||
2006 !data
.hctx
->dispatch_busy
) {
2007 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
2009 blk_mq_sched_insert_request(rq
, false, true, true);
2015 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2016 unsigned int hctx_idx
)
2020 if (tags
->rqs
&& set
->ops
->exit_request
) {
2023 for (i
= 0; i
< tags
->nr_tags
; i
++) {
2024 struct request
*rq
= tags
->static_rqs
[i
];
2028 set
->ops
->exit_request(set
, rq
, hctx_idx
);
2029 tags
->static_rqs
[i
] = NULL
;
2033 while (!list_empty(&tags
->page_list
)) {
2034 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
2035 list_del_init(&page
->lru
);
2037 * Remove kmemleak object previously allocated in
2038 * blk_mq_alloc_rqs().
2040 kmemleak_free(page_address(page
));
2041 __free_pages(page
, page
->private);
2045 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
2049 kfree(tags
->static_rqs
);
2050 tags
->static_rqs
= NULL
;
2052 blk_mq_free_tags(tags
);
2055 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
2056 unsigned int hctx_idx
,
2057 unsigned int nr_tags
,
2058 unsigned int reserved_tags
)
2060 struct blk_mq_tags
*tags
;
2063 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2064 if (node
== NUMA_NO_NODE
)
2065 node
= set
->numa_node
;
2067 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
2068 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
2072 tags
->rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2073 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2076 blk_mq_free_tags(tags
);
2080 tags
->static_rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2081 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2083 if (!tags
->static_rqs
) {
2085 blk_mq_free_tags(tags
);
2092 static size_t order_to_size(unsigned int order
)
2094 return (size_t)PAGE_SIZE
<< order
;
2097 static int blk_mq_init_request(struct blk_mq_tag_set
*set
, struct request
*rq
,
2098 unsigned int hctx_idx
, int node
)
2102 if (set
->ops
->init_request
) {
2103 ret
= set
->ops
->init_request(set
, rq
, hctx_idx
, node
);
2108 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
2112 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2113 unsigned int hctx_idx
, unsigned int depth
)
2115 unsigned int i
, j
, entries_per_page
, max_order
= 4;
2116 size_t rq_size
, left
;
2119 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2120 if (node
== NUMA_NO_NODE
)
2121 node
= set
->numa_node
;
2123 INIT_LIST_HEAD(&tags
->page_list
);
2126 * rq_size is the size of the request plus driver payload, rounded
2127 * to the cacheline size
2129 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
2131 left
= rq_size
* depth
;
2133 for (i
= 0; i
< depth
; ) {
2134 int this_order
= max_order
;
2139 while (this_order
&& left
< order_to_size(this_order
- 1))
2143 page
= alloc_pages_node(node
,
2144 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
2150 if (order_to_size(this_order
) < rq_size
)
2157 page
->private = this_order
;
2158 list_add_tail(&page
->lru
, &tags
->page_list
);
2160 p
= page_address(page
);
2162 * Allow kmemleak to scan these pages as they contain pointers
2163 * to additional allocations like via ops->init_request().
2165 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
2166 entries_per_page
= order_to_size(this_order
) / rq_size
;
2167 to_do
= min(entries_per_page
, depth
- i
);
2168 left
-= to_do
* rq_size
;
2169 for (j
= 0; j
< to_do
; j
++) {
2170 struct request
*rq
= p
;
2172 tags
->static_rqs
[i
] = rq
;
2173 if (blk_mq_init_request(set
, rq
, hctx_idx
, node
)) {
2174 tags
->static_rqs
[i
] = NULL
;
2185 blk_mq_free_rqs(set
, tags
, hctx_idx
);
2190 * 'cpu' is going away. splice any existing rq_list entries from this
2191 * software queue to the hw queue dispatch list, and ensure that it
2194 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
2196 struct blk_mq_hw_ctx
*hctx
;
2197 struct blk_mq_ctx
*ctx
;
2199 enum hctx_type type
;
2201 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
2202 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
2205 spin_lock(&ctx
->lock
);
2206 if (!list_empty(&ctx
->rq_lists
[type
])) {
2207 list_splice_init(&ctx
->rq_lists
[type
], &tmp
);
2208 blk_mq_hctx_clear_pending(hctx
, ctx
);
2210 spin_unlock(&ctx
->lock
);
2212 if (list_empty(&tmp
))
2215 spin_lock(&hctx
->lock
);
2216 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
2217 spin_unlock(&hctx
->lock
);
2219 blk_mq_run_hw_queue(hctx
, true);
2223 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2225 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2229 /* hctx->ctxs will be freed in queue's release handler */
2230 static void blk_mq_exit_hctx(struct request_queue
*q
,
2231 struct blk_mq_tag_set
*set
,
2232 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2234 if (blk_mq_hw_queue_mapped(hctx
))
2235 blk_mq_tag_idle(hctx
);
2237 if (set
->ops
->exit_request
)
2238 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2240 if (set
->ops
->exit_hctx
)
2241 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2243 blk_mq_remove_cpuhp(hctx
);
2245 spin_lock(&q
->unused_hctx_lock
);
2246 list_add(&hctx
->hctx_list
, &q
->unused_hctx_list
);
2247 spin_unlock(&q
->unused_hctx_lock
);
2250 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2251 struct blk_mq_tag_set
*set
, int nr_queue
)
2253 struct blk_mq_hw_ctx
*hctx
;
2256 queue_for_each_hw_ctx(q
, hctx
, i
) {
2259 blk_mq_debugfs_unregister_hctx(hctx
);
2260 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2264 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2266 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2268 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, srcu
),
2269 __alignof__(struct blk_mq_hw_ctx
)) !=
2270 sizeof(struct blk_mq_hw_ctx
));
2272 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2273 hw_ctx_size
+= sizeof(struct srcu_struct
);
2278 static int blk_mq_init_hctx(struct request_queue
*q
,
2279 struct blk_mq_tag_set
*set
,
2280 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2282 hctx
->queue_num
= hctx_idx
;
2284 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2286 hctx
->tags
= set
->tags
[hctx_idx
];
2288 if (set
->ops
->init_hctx
&&
2289 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2290 goto unregister_cpu_notifier
;
2292 if (blk_mq_init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
2298 if (set
->ops
->exit_hctx
)
2299 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2300 unregister_cpu_notifier
:
2301 blk_mq_remove_cpuhp(hctx
);
2305 static struct blk_mq_hw_ctx
*
2306 blk_mq_alloc_hctx(struct request_queue
*q
, struct blk_mq_tag_set
*set
,
2309 struct blk_mq_hw_ctx
*hctx
;
2310 gfp_t gfp
= GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
;
2312 hctx
= kzalloc_node(blk_mq_hw_ctx_size(set
), gfp
, node
);
2314 goto fail_alloc_hctx
;
2316 if (!zalloc_cpumask_var_node(&hctx
->cpumask
, gfp
, node
))
2319 atomic_set(&hctx
->nr_active
, 0);
2320 if (node
== NUMA_NO_NODE
)
2321 node
= set
->numa_node
;
2322 hctx
->numa_node
= node
;
2324 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2325 spin_lock_init(&hctx
->lock
);
2326 INIT_LIST_HEAD(&hctx
->dispatch
);
2328 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
2330 INIT_LIST_HEAD(&hctx
->hctx_list
);
2333 * Allocate space for all possible cpus to avoid allocation at
2336 hctx
->ctxs
= kmalloc_array_node(nr_cpu_ids
, sizeof(void *),
2341 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8),
2346 spin_lock_init(&hctx
->dispatch_wait_lock
);
2347 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
2348 INIT_LIST_HEAD(&hctx
->dispatch_wait
.entry
);
2350 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
,
2355 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2356 init_srcu_struct(hctx
->srcu
);
2357 blk_mq_hctx_kobj_init(hctx
);
2362 sbitmap_free(&hctx
->ctx_map
);
2366 free_cpumask_var(hctx
->cpumask
);
2373 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2374 unsigned int nr_hw_queues
)
2376 struct blk_mq_tag_set
*set
= q
->tag_set
;
2379 for_each_possible_cpu(i
) {
2380 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2381 struct blk_mq_hw_ctx
*hctx
;
2385 spin_lock_init(&__ctx
->lock
);
2386 for (k
= HCTX_TYPE_DEFAULT
; k
< HCTX_MAX_TYPES
; k
++)
2387 INIT_LIST_HEAD(&__ctx
->rq_lists
[k
]);
2392 * Set local node, IFF we have more than one hw queue. If
2393 * not, we remain on the home node of the device
2395 for (j
= 0; j
< set
->nr_maps
; j
++) {
2396 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2397 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2398 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2403 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2407 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2408 set
->queue_depth
, set
->reserved_tags
);
2409 if (!set
->tags
[hctx_idx
])
2412 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2417 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2418 set
->tags
[hctx_idx
] = NULL
;
2422 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2423 unsigned int hctx_idx
)
2425 if (set
->tags
&& set
->tags
[hctx_idx
]) {
2426 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2427 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2428 set
->tags
[hctx_idx
] = NULL
;
2432 static void blk_mq_map_swqueue(struct request_queue
*q
)
2434 unsigned int i
, j
, hctx_idx
;
2435 struct blk_mq_hw_ctx
*hctx
;
2436 struct blk_mq_ctx
*ctx
;
2437 struct blk_mq_tag_set
*set
= q
->tag_set
;
2439 queue_for_each_hw_ctx(q
, hctx
, i
) {
2440 cpumask_clear(hctx
->cpumask
);
2442 hctx
->dispatch_from
= NULL
;
2446 * Map software to hardware queues.
2448 * If the cpu isn't present, the cpu is mapped to first hctx.
2450 for_each_possible_cpu(i
) {
2451 hctx_idx
= set
->map
[HCTX_TYPE_DEFAULT
].mq_map
[i
];
2452 /* unmapped hw queue can be remapped after CPU topo changed */
2453 if (!set
->tags
[hctx_idx
] &&
2454 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2456 * If tags initialization fail for some hctx,
2457 * that hctx won't be brought online. In this
2458 * case, remap the current ctx to hctx[0] which
2459 * is guaranteed to always have tags allocated
2461 set
->map
[HCTX_TYPE_DEFAULT
].mq_map
[i
] = 0;
2464 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2465 for (j
= 0; j
< set
->nr_maps
; j
++) {
2466 if (!set
->map
[j
].nr_queues
) {
2467 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2468 HCTX_TYPE_DEFAULT
, i
);
2472 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2473 ctx
->hctxs
[j
] = hctx
;
2475 * If the CPU is already set in the mask, then we've
2476 * mapped this one already. This can happen if
2477 * devices share queues across queue maps.
2479 if (cpumask_test_cpu(i
, hctx
->cpumask
))
2482 cpumask_set_cpu(i
, hctx
->cpumask
);
2484 ctx
->index_hw
[hctx
->type
] = hctx
->nr_ctx
;
2485 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2488 * If the nr_ctx type overflows, we have exceeded the
2489 * amount of sw queues we can support.
2491 BUG_ON(!hctx
->nr_ctx
);
2494 for (; j
< HCTX_MAX_TYPES
; j
++)
2495 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2496 HCTX_TYPE_DEFAULT
, i
);
2499 queue_for_each_hw_ctx(q
, hctx
, i
) {
2501 * If no software queues are mapped to this hardware queue,
2502 * disable it and free the request entries.
2504 if (!hctx
->nr_ctx
) {
2505 /* Never unmap queue 0. We need it as a
2506 * fallback in case of a new remap fails
2509 if (i
&& set
->tags
[i
])
2510 blk_mq_free_map_and_requests(set
, i
);
2516 hctx
->tags
= set
->tags
[i
];
2517 WARN_ON(!hctx
->tags
);
2520 * Set the map size to the number of mapped software queues.
2521 * This is more accurate and more efficient than looping
2522 * over all possibly mapped software queues.
2524 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2527 * Initialize batch roundrobin counts
2529 hctx
->next_cpu
= blk_mq_first_mapped_cpu(hctx
);
2530 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2535 * Caller needs to ensure that we're either frozen/quiesced, or that
2536 * the queue isn't live yet.
2538 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2540 struct blk_mq_hw_ctx
*hctx
;
2543 queue_for_each_hw_ctx(q
, hctx
, i
) {
2545 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2547 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2551 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2554 struct request_queue
*q
;
2556 lockdep_assert_held(&set
->tag_list_lock
);
2558 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2559 blk_mq_freeze_queue(q
);
2560 queue_set_hctx_shared(q
, shared
);
2561 blk_mq_unfreeze_queue(q
);
2565 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2567 struct blk_mq_tag_set
*set
= q
->tag_set
;
2569 mutex_lock(&set
->tag_list_lock
);
2570 list_del_rcu(&q
->tag_set_list
);
2571 if (list_is_singular(&set
->tag_list
)) {
2572 /* just transitioned to unshared */
2573 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2574 /* update existing queue */
2575 blk_mq_update_tag_set_depth(set
, false);
2577 mutex_unlock(&set
->tag_list_lock
);
2578 INIT_LIST_HEAD(&q
->tag_set_list
);
2581 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2582 struct request_queue
*q
)
2584 mutex_lock(&set
->tag_list_lock
);
2587 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2589 if (!list_empty(&set
->tag_list
) &&
2590 !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2591 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2592 /* update existing queue */
2593 blk_mq_update_tag_set_depth(set
, true);
2595 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2596 queue_set_hctx_shared(q
, true);
2597 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2599 mutex_unlock(&set
->tag_list_lock
);
2602 /* All allocations will be freed in release handler of q->mq_kobj */
2603 static int blk_mq_alloc_ctxs(struct request_queue
*q
)
2605 struct blk_mq_ctxs
*ctxs
;
2608 ctxs
= kzalloc(sizeof(*ctxs
), GFP_KERNEL
);
2612 ctxs
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2613 if (!ctxs
->queue_ctx
)
2616 for_each_possible_cpu(cpu
) {
2617 struct blk_mq_ctx
*ctx
= per_cpu_ptr(ctxs
->queue_ctx
, cpu
);
2621 q
->mq_kobj
= &ctxs
->kobj
;
2622 q
->queue_ctx
= ctxs
->queue_ctx
;
2631 * It is the actual release handler for mq, but we do it from
2632 * request queue's release handler for avoiding use-after-free
2633 * and headache because q->mq_kobj shouldn't have been introduced,
2634 * but we can't group ctx/kctx kobj without it.
2636 void blk_mq_release(struct request_queue
*q
)
2638 struct blk_mq_hw_ctx
*hctx
, *next
;
2641 queue_for_each_hw_ctx(q
, hctx
, i
)
2642 WARN_ON_ONCE(hctx
&& list_empty(&hctx
->hctx_list
));
2644 /* all hctx are in .unused_hctx_list now */
2645 list_for_each_entry_safe(hctx
, next
, &q
->unused_hctx_list
, hctx_list
) {
2646 list_del_init(&hctx
->hctx_list
);
2647 kobject_put(&hctx
->kobj
);
2650 kfree(q
->queue_hw_ctx
);
2653 * release .mq_kobj and sw queue's kobject now because
2654 * both share lifetime with request queue.
2656 blk_mq_sysfs_deinit(q
);
2659 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2661 struct request_queue
*uninit_q
, *q
;
2663 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2665 return ERR_PTR(-ENOMEM
);
2668 * Initialize the queue without an elevator. device_add_disk() will do
2669 * the initialization.
2671 q
= blk_mq_init_allocated_queue(set
, uninit_q
, false);
2673 blk_cleanup_queue(uninit_q
);
2677 EXPORT_SYMBOL(blk_mq_init_queue
);
2680 * Helper for setting up a queue with mq ops, given queue depth, and
2681 * the passed in mq ops flags.
2683 struct request_queue
*blk_mq_init_sq_queue(struct blk_mq_tag_set
*set
,
2684 const struct blk_mq_ops
*ops
,
2685 unsigned int queue_depth
,
2686 unsigned int set_flags
)
2688 struct request_queue
*q
;
2691 memset(set
, 0, sizeof(*set
));
2693 set
->nr_hw_queues
= 1;
2695 set
->queue_depth
= queue_depth
;
2696 set
->numa_node
= NUMA_NO_NODE
;
2697 set
->flags
= set_flags
;
2699 ret
= blk_mq_alloc_tag_set(set
);
2701 return ERR_PTR(ret
);
2703 q
= blk_mq_init_queue(set
);
2705 blk_mq_free_tag_set(set
);
2711 EXPORT_SYMBOL(blk_mq_init_sq_queue
);
2713 static struct blk_mq_hw_ctx
*blk_mq_alloc_and_init_hctx(
2714 struct blk_mq_tag_set
*set
, struct request_queue
*q
,
2715 int hctx_idx
, int node
)
2717 struct blk_mq_hw_ctx
*hctx
= NULL
, *tmp
;
2719 /* reuse dead hctx first */
2720 spin_lock(&q
->unused_hctx_lock
);
2721 list_for_each_entry(tmp
, &q
->unused_hctx_list
, hctx_list
) {
2722 if (tmp
->numa_node
== node
) {
2728 list_del_init(&hctx
->hctx_list
);
2729 spin_unlock(&q
->unused_hctx_lock
);
2732 hctx
= blk_mq_alloc_hctx(q
, set
, node
);
2736 if (blk_mq_init_hctx(q
, set
, hctx
, hctx_idx
))
2742 kobject_put(&hctx
->kobj
);
2747 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2748 struct request_queue
*q
)
2751 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2753 if (q
->nr_hw_queues
< set
->nr_hw_queues
) {
2754 struct blk_mq_hw_ctx
**new_hctxs
;
2756 new_hctxs
= kcalloc_node(set
->nr_hw_queues
,
2757 sizeof(*new_hctxs
), GFP_KERNEL
,
2762 memcpy(new_hctxs
, hctxs
, q
->nr_hw_queues
*
2764 q
->queue_hw_ctx
= new_hctxs
;
2765 q
->nr_hw_queues
= set
->nr_hw_queues
;
2770 /* protect against switching io scheduler */
2771 mutex_lock(&q
->sysfs_lock
);
2772 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2774 struct blk_mq_hw_ctx
*hctx
;
2776 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], i
);
2778 * If the hw queue has been mapped to another numa node,
2779 * we need to realloc the hctx. If allocation fails, fallback
2780 * to use the previous one.
2782 if (hctxs
[i
] && (hctxs
[i
]->numa_node
== node
))
2785 hctx
= blk_mq_alloc_and_init_hctx(set
, q
, i
, node
);
2788 blk_mq_exit_hctx(q
, set
, hctxs
[i
], i
);
2792 pr_warn("Allocate new hctx on node %d fails,\
2793 fallback to previous one on node %d\n",
2794 node
, hctxs
[i
]->numa_node
);
2800 * Increasing nr_hw_queues fails. Free the newly allocated
2801 * hctxs and keep the previous q->nr_hw_queues.
2803 if (i
!= set
->nr_hw_queues
) {
2804 j
= q
->nr_hw_queues
;
2808 end
= q
->nr_hw_queues
;
2809 q
->nr_hw_queues
= set
->nr_hw_queues
;
2812 for (; j
< end
; j
++) {
2813 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2817 blk_mq_free_map_and_requests(set
, j
);
2818 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2822 mutex_unlock(&q
->sysfs_lock
);
2825 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2826 struct request_queue
*q
,
2829 /* mark the queue as mq asap */
2830 q
->mq_ops
= set
->ops
;
2832 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2833 blk_mq_poll_stats_bkt
,
2834 BLK_MQ_POLL_STATS_BKTS
, q
);
2838 if (blk_mq_alloc_ctxs(q
))
2841 /* init q->mq_kobj and sw queues' kobjects */
2842 blk_mq_sysfs_init(q
);
2844 INIT_LIST_HEAD(&q
->unused_hctx_list
);
2845 spin_lock_init(&q
->unused_hctx_lock
);
2847 blk_mq_realloc_hw_ctxs(set
, q
);
2848 if (!q
->nr_hw_queues
)
2851 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2852 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2856 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2857 if (set
->nr_maps
> HCTX_TYPE_POLL
&&
2858 set
->map
[HCTX_TYPE_POLL
].nr_queues
)
2859 blk_queue_flag_set(QUEUE_FLAG_POLL
, q
);
2861 q
->sg_reserved_size
= INT_MAX
;
2863 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2864 INIT_LIST_HEAD(&q
->requeue_list
);
2865 spin_lock_init(&q
->requeue_lock
);
2867 blk_queue_make_request(q
, blk_mq_make_request
);
2870 * Do this after blk_queue_make_request() overrides it...
2872 q
->nr_requests
= set
->queue_depth
;
2875 * Default to classic polling
2877 q
->poll_nsec
= BLK_MQ_POLL_CLASSIC
;
2879 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2880 blk_mq_add_queue_tag_set(set
, q
);
2881 blk_mq_map_swqueue(q
);
2884 elevator_init_mq(q
);
2889 kfree(q
->queue_hw_ctx
);
2890 q
->nr_hw_queues
= 0;
2891 blk_mq_sysfs_deinit(q
);
2893 blk_stat_free_callback(q
->poll_cb
);
2897 return ERR_PTR(-ENOMEM
);
2899 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2901 /* tags can _not_ be used after returning from blk_mq_exit_queue */
2902 void blk_mq_exit_queue(struct request_queue
*q
)
2904 struct blk_mq_tag_set
*set
= q
->tag_set
;
2906 blk_mq_del_queue_tag_set(q
);
2907 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2910 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2914 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2915 if (!__blk_mq_alloc_rq_map(set
, i
))
2922 blk_mq_free_rq_map(set
->tags
[i
]);
2928 * Allocate the request maps associated with this tag_set. Note that this
2929 * may reduce the depth asked for, if memory is tight. set->queue_depth
2930 * will be updated to reflect the allocated depth.
2932 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2937 depth
= set
->queue_depth
;
2939 err
= __blk_mq_alloc_rq_maps(set
);
2943 set
->queue_depth
>>= 1;
2944 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2948 } while (set
->queue_depth
);
2950 if (!set
->queue_depth
|| err
) {
2951 pr_err("blk-mq: failed to allocate request map\n");
2955 if (depth
!= set
->queue_depth
)
2956 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2957 depth
, set
->queue_depth
);
2962 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2964 if (set
->ops
->map_queues
&& !is_kdump_kernel()) {
2968 * transport .map_queues is usually done in the following
2971 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
2972 * mask = get_cpu_mask(queue)
2973 * for_each_cpu(cpu, mask)
2974 * set->map[x].mq_map[cpu] = queue;
2977 * When we need to remap, the table has to be cleared for
2978 * killing stale mapping since one CPU may not be mapped
2981 for (i
= 0; i
< set
->nr_maps
; i
++)
2982 blk_mq_clear_mq_map(&set
->map
[i
]);
2984 return set
->ops
->map_queues(set
);
2986 BUG_ON(set
->nr_maps
> 1);
2987 return blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
2991 static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set
*set
,
2992 int cur_nr_hw_queues
, int new_nr_hw_queues
)
2994 struct blk_mq_tags
**new_tags
;
2996 if (cur_nr_hw_queues
>= new_nr_hw_queues
)
2999 new_tags
= kcalloc_node(new_nr_hw_queues
, sizeof(struct blk_mq_tags
*),
3000 GFP_KERNEL
, set
->numa_node
);
3005 memcpy(new_tags
, set
->tags
, cur_nr_hw_queues
*
3006 sizeof(*set
->tags
));
3008 set
->tags
= new_tags
;
3009 set
->nr_hw_queues
= new_nr_hw_queues
;
3015 * Alloc a tag set to be associated with one or more request queues.
3016 * May fail with EINVAL for various error conditions. May adjust the
3017 * requested depth down, if it's too large. In that case, the set
3018 * value will be stored in set->queue_depth.
3020 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
3024 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
3026 if (!set
->nr_hw_queues
)
3028 if (!set
->queue_depth
)
3030 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
3033 if (!set
->ops
->queue_rq
)
3036 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
3039 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
3040 pr_info("blk-mq: reduced tag depth to %u\n",
3042 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
3047 else if (set
->nr_maps
> HCTX_MAX_TYPES
)
3051 * If a crashdump is active, then we are potentially in a very
3052 * memory constrained environment. Limit us to 1 queue and
3053 * 64 tags to prevent using too much memory.
3055 if (is_kdump_kernel()) {
3056 set
->nr_hw_queues
= 1;
3058 set
->queue_depth
= min(64U, set
->queue_depth
);
3061 * There is no use for more h/w queues than cpus if we just have
3064 if (set
->nr_maps
== 1 && set
->nr_hw_queues
> nr_cpu_ids
)
3065 set
->nr_hw_queues
= nr_cpu_ids
;
3067 if (blk_mq_realloc_tag_set_tags(set
, 0, set
->nr_hw_queues
) < 0)
3071 for (i
= 0; i
< set
->nr_maps
; i
++) {
3072 set
->map
[i
].mq_map
= kcalloc_node(nr_cpu_ids
,
3073 sizeof(set
->map
[i
].mq_map
[0]),
3074 GFP_KERNEL
, set
->numa_node
);
3075 if (!set
->map
[i
].mq_map
)
3076 goto out_free_mq_map
;
3077 set
->map
[i
].nr_queues
= is_kdump_kernel() ? 1 : set
->nr_hw_queues
;
3080 ret
= blk_mq_update_queue_map(set
);
3082 goto out_free_mq_map
;
3084 ret
= blk_mq_alloc_rq_maps(set
);
3086 goto out_free_mq_map
;
3088 mutex_init(&set
->tag_list_lock
);
3089 INIT_LIST_HEAD(&set
->tag_list
);
3094 for (i
= 0; i
< set
->nr_maps
; i
++) {
3095 kfree(set
->map
[i
].mq_map
);
3096 set
->map
[i
].mq_map
= NULL
;
3102 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
3104 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
3108 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
3109 blk_mq_free_map_and_requests(set
, i
);
3111 for (j
= 0; j
< set
->nr_maps
; j
++) {
3112 kfree(set
->map
[j
].mq_map
);
3113 set
->map
[j
].mq_map
= NULL
;
3119 EXPORT_SYMBOL(blk_mq_free_tag_set
);
3121 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
3123 struct blk_mq_tag_set
*set
= q
->tag_set
;
3124 struct blk_mq_hw_ctx
*hctx
;
3130 if (q
->nr_requests
== nr
)
3133 blk_mq_freeze_queue(q
);
3134 blk_mq_quiesce_queue(q
);
3137 queue_for_each_hw_ctx(q
, hctx
, i
) {
3141 * If we're using an MQ scheduler, just update the scheduler
3142 * queue depth. This is similar to what the old code would do.
3144 if (!hctx
->sched_tags
) {
3145 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
3148 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
3153 if (q
->elevator
&& q
->elevator
->type
->ops
.depth_updated
)
3154 q
->elevator
->type
->ops
.depth_updated(hctx
);
3158 q
->nr_requests
= nr
;
3160 blk_mq_unquiesce_queue(q
);
3161 blk_mq_unfreeze_queue(q
);
3167 * request_queue and elevator_type pair.
3168 * It is just used by __blk_mq_update_nr_hw_queues to cache
3169 * the elevator_type associated with a request_queue.
3171 struct blk_mq_qe_pair
{
3172 struct list_head node
;
3173 struct request_queue
*q
;
3174 struct elevator_type
*type
;
3178 * Cache the elevator_type in qe pair list and switch the
3179 * io scheduler to 'none'
3181 static bool blk_mq_elv_switch_none(struct list_head
*head
,
3182 struct request_queue
*q
)
3184 struct blk_mq_qe_pair
*qe
;
3189 qe
= kmalloc(sizeof(*qe
), GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
);
3193 INIT_LIST_HEAD(&qe
->node
);
3195 qe
->type
= q
->elevator
->type
;
3196 list_add(&qe
->node
, head
);
3198 mutex_lock(&q
->sysfs_lock
);
3200 * After elevator_switch_mq, the previous elevator_queue will be
3201 * released by elevator_release. The reference of the io scheduler
3202 * module get by elevator_get will also be put. So we need to get
3203 * a reference of the io scheduler module here to prevent it to be
3206 __module_get(qe
->type
->elevator_owner
);
3207 elevator_switch_mq(q
, NULL
);
3208 mutex_unlock(&q
->sysfs_lock
);
3213 static void blk_mq_elv_switch_back(struct list_head
*head
,
3214 struct request_queue
*q
)
3216 struct blk_mq_qe_pair
*qe
;
3217 struct elevator_type
*t
= NULL
;
3219 list_for_each_entry(qe
, head
, node
)
3228 list_del(&qe
->node
);
3231 mutex_lock(&q
->sysfs_lock
);
3232 elevator_switch_mq(q
, t
);
3233 mutex_unlock(&q
->sysfs_lock
);
3236 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
3239 struct request_queue
*q
;
3241 int prev_nr_hw_queues
;
3243 lockdep_assert_held(&set
->tag_list_lock
);
3245 if (set
->nr_maps
== 1 && nr_hw_queues
> nr_cpu_ids
)
3246 nr_hw_queues
= nr_cpu_ids
;
3247 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
3250 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3251 blk_mq_freeze_queue(q
);
3253 * Switch IO scheduler to 'none', cleaning up the data associated
3254 * with the previous scheduler. We will switch back once we are done
3255 * updating the new sw to hw queue mappings.
3257 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3258 if (!blk_mq_elv_switch_none(&head
, q
))
3261 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3262 blk_mq_debugfs_unregister_hctxs(q
);
3263 blk_mq_sysfs_unregister(q
);
3266 if (blk_mq_realloc_tag_set_tags(set
, set
->nr_hw_queues
, nr_hw_queues
) <
3270 prev_nr_hw_queues
= set
->nr_hw_queues
;
3271 set
->nr_hw_queues
= nr_hw_queues
;
3272 blk_mq_update_queue_map(set
);
3274 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3275 blk_mq_realloc_hw_ctxs(set
, q
);
3276 if (q
->nr_hw_queues
!= set
->nr_hw_queues
) {
3277 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3278 nr_hw_queues
, prev_nr_hw_queues
);
3279 set
->nr_hw_queues
= prev_nr_hw_queues
;
3280 blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3283 blk_mq_map_swqueue(q
);
3287 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3288 blk_mq_sysfs_register(q
);
3289 blk_mq_debugfs_register_hctxs(q
);
3293 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3294 blk_mq_elv_switch_back(&head
, q
);
3296 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3297 blk_mq_unfreeze_queue(q
);
3300 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
3302 mutex_lock(&set
->tag_list_lock
);
3303 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
3304 mutex_unlock(&set
->tag_list_lock
);
3306 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
3308 /* Enable polling stats and return whether they were already enabled. */
3309 static bool blk_poll_stats_enable(struct request_queue
*q
)
3311 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3312 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS
, q
))
3314 blk_stat_add_callback(q
, q
->poll_cb
);
3318 static void blk_mq_poll_stats_start(struct request_queue
*q
)
3321 * We don't arm the callback if polling stats are not enabled or the
3322 * callback is already active.
3324 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3325 blk_stat_is_active(q
->poll_cb
))
3328 blk_stat_activate_msecs(q
->poll_cb
, 100);
3331 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
3333 struct request_queue
*q
= cb
->data
;
3336 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
3337 if (cb
->stat
[bucket
].nr_samples
)
3338 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
3342 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
3343 struct blk_mq_hw_ctx
*hctx
,
3346 unsigned long ret
= 0;
3350 * If stats collection isn't on, don't sleep but turn it on for
3353 if (!blk_poll_stats_enable(q
))
3357 * As an optimistic guess, use half of the mean service time
3358 * for this type of request. We can (and should) make this smarter.
3359 * For instance, if the completion latencies are tight, we can
3360 * get closer than just half the mean. This is especially
3361 * important on devices where the completion latencies are longer
3362 * than ~10 usec. We do use the stats for the relevant IO size
3363 * if available which does lead to better estimates.
3365 bucket
= blk_mq_poll_stats_bkt(rq
);
3369 if (q
->poll_stat
[bucket
].nr_samples
)
3370 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
3375 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
3376 struct blk_mq_hw_ctx
*hctx
,
3379 struct hrtimer_sleeper hs
;
3380 enum hrtimer_mode mode
;
3384 if (rq
->rq_flags
& RQF_MQ_POLL_SLEPT
)
3388 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3390 * 0: use half of prev avg
3391 * >0: use this specific value
3393 if (q
->poll_nsec
> 0)
3394 nsecs
= q
->poll_nsec
;
3396 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
3401 rq
->rq_flags
|= RQF_MQ_POLL_SLEPT
;
3404 * This will be replaced with the stats tracking code, using
3405 * 'avg_completion_time / 2' as the pre-sleep target.
3409 mode
= HRTIMER_MODE_REL
;
3410 hrtimer_init_sleeper_on_stack(&hs
, CLOCK_MONOTONIC
, mode
);
3411 hrtimer_set_expires(&hs
.timer
, kt
);
3414 if (blk_mq_rq_state(rq
) == MQ_RQ_COMPLETE
)
3416 set_current_state(TASK_UNINTERRUPTIBLE
);
3417 hrtimer_sleeper_start_expires(&hs
, mode
);
3420 hrtimer_cancel(&hs
.timer
);
3421 mode
= HRTIMER_MODE_ABS
;
3422 } while (hs
.task
&& !signal_pending(current
));
3424 __set_current_state(TASK_RUNNING
);
3425 destroy_hrtimer_on_stack(&hs
.timer
);
3429 static bool blk_mq_poll_hybrid(struct request_queue
*q
,
3430 struct blk_mq_hw_ctx
*hctx
, blk_qc_t cookie
)
3434 if (q
->poll_nsec
== BLK_MQ_POLL_CLASSIC
)
3437 if (!blk_qc_t_is_internal(cookie
))
3438 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
3440 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
3442 * With scheduling, if the request has completed, we'll
3443 * get a NULL return here, as we clear the sched tag when
3444 * that happens. The request still remains valid, like always,
3445 * so we should be safe with just the NULL check.
3451 return blk_mq_poll_hybrid_sleep(q
, hctx
, rq
);
3455 * blk_poll - poll for IO completions
3457 * @cookie: cookie passed back at IO submission time
3458 * @spin: whether to spin for completions
3461 * Poll for completions on the passed in queue. Returns number of
3462 * completed entries found. If @spin is true, then blk_poll will continue
3463 * looping until at least one completion is found, unless the task is
3464 * otherwise marked running (or we need to reschedule).
3466 int blk_poll(struct request_queue
*q
, blk_qc_t cookie
, bool spin
)
3468 struct blk_mq_hw_ctx
*hctx
;
3471 if (!blk_qc_t_valid(cookie
) ||
3472 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3476 blk_flush_plug_list(current
->plug
, false);
3478 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
3481 * If we sleep, have the caller restart the poll loop to reset
3482 * the state. Like for the other success return cases, the
3483 * caller is responsible for checking if the IO completed. If
3484 * the IO isn't complete, we'll get called again and will go
3485 * straight to the busy poll loop.
3487 if (blk_mq_poll_hybrid(q
, hctx
, cookie
))
3490 hctx
->poll_considered
++;
3492 state
= current
->state
;
3496 hctx
->poll_invoked
++;
3498 ret
= q
->mq_ops
->poll(hctx
);
3500 hctx
->poll_success
++;
3501 __set_current_state(TASK_RUNNING
);
3505 if (signal_pending_state(state
, current
))
3506 __set_current_state(TASK_RUNNING
);
3508 if (current
->state
== TASK_RUNNING
)
3510 if (ret
< 0 || !spin
)
3513 } while (!need_resched());
3515 __set_current_state(TASK_RUNNING
);
3518 EXPORT_SYMBOL_GPL(blk_poll
);
3520 unsigned int blk_mq_rq_cpu(struct request
*rq
)
3522 return rq
->mq_ctx
->cpu
;
3524 EXPORT_SYMBOL(blk_mq_rq_cpu
);
3526 static int __init
blk_mq_init(void)
3528 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
3529 blk_mq_hctx_notify_dead
);
3532 subsys_initcall(blk_mq_init
);