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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Block multiqueue core code
4 *
5 * Copyright (C) 2013-2014 Jens Axboe
6 * Copyright (C) 2013-2014 Christoph Hellwig
7 */
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>
14#include <linux/mm.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>
29
30#include <trace/events/block.h>
31
32#include <linux/blk-mq.h>
33#include <linux/t10-pi.h>
34#include "blk.h"
35#include "blk-mq.h"
36#include "blk-mq-debugfs.h"
37#include "blk-mq-tag.h"
38#include "blk-pm.h"
39#include "blk-stat.h"
40#include "blk-mq-sched.h"
41#include "blk-rq-qos.h"
42
43static void blk_mq_poll_stats_start(struct request_queue *q);
44static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
45
46static int blk_mq_poll_stats_bkt(const struct request *rq)
47{
48 int ddir, sectors, bucket;
49
50 ddir = rq_data_dir(rq);
51 sectors = blk_rq_stats_sectors(rq);
52
53 bucket = ddir + 2 * ilog2(sectors);
54
55 if (bucket < 0)
56 return -1;
57 else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
58 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
59
60 return bucket;
61}
62
63/*
64 * Check if any of the ctx, dispatch list or elevator
65 * have pending work in this hardware queue.
66 */
67static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
68{
69 return !list_empty_careful(&hctx->dispatch) ||
70 sbitmap_any_bit_set(&hctx->ctx_map) ||
71 blk_mq_sched_has_work(hctx);
72}
73
74/*
75 * Mark this ctx as having pending work in this hardware queue
76 */
77static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
78 struct blk_mq_ctx *ctx)
79{
80 const int bit = ctx->index_hw[hctx->type];
81
82 if (!sbitmap_test_bit(&hctx->ctx_map, bit))
83 sbitmap_set_bit(&hctx->ctx_map, bit);
84}
85
86static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
87 struct blk_mq_ctx *ctx)
88{
89 const int bit = ctx->index_hw[hctx->type];
90
91 sbitmap_clear_bit(&hctx->ctx_map, bit);
92}
93
94struct mq_inflight {
95 struct hd_struct *part;
96 unsigned int *inflight;
97};
98
99static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
100 struct request *rq, void *priv,
101 bool reserved)
102{
103 struct mq_inflight *mi = priv;
104
105 /*
106 * index[0] counts the specific partition that was asked for.
107 */
108 if (rq->part == mi->part)
109 mi->inflight[0]++;
110
111 return true;
112}
113
114unsigned int blk_mq_in_flight(struct request_queue *q, struct hd_struct *part)
115{
116 unsigned inflight[2];
117 struct mq_inflight mi = { .part = part, .inflight = inflight, };
118
119 inflight[0] = inflight[1] = 0;
120 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
121
122 return inflight[0];
123}
124
125static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
126 struct request *rq, void *priv,
127 bool reserved)
128{
129 struct mq_inflight *mi = priv;
130
131 if (rq->part == mi->part)
132 mi->inflight[rq_data_dir(rq)]++;
133
134 return true;
135}
136
137void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
138 unsigned int inflight[2])
139{
140 struct mq_inflight mi = { .part = part, .inflight = inflight, };
141
142 inflight[0] = inflight[1] = 0;
143 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi);
144}
145
146void blk_freeze_queue_start(struct request_queue *q)
147{
148 mutex_lock(&q->mq_freeze_lock);
149 if (++q->mq_freeze_depth == 1) {
150 percpu_ref_kill(&q->q_usage_counter);
151 mutex_unlock(&q->mq_freeze_lock);
152 if (queue_is_mq(q))
153 blk_mq_run_hw_queues(q, false);
154 } else {
155 mutex_unlock(&q->mq_freeze_lock);
156 }
157}
158EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
159
160void blk_mq_freeze_queue_wait(struct request_queue *q)
161{
162 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
163}
164EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
165
166int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
167 unsigned long timeout)
168{
169 return wait_event_timeout(q->mq_freeze_wq,
170 percpu_ref_is_zero(&q->q_usage_counter),
171 timeout);
172}
173EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
174
175/*
176 * Guarantee no request is in use, so we can change any data structure of
177 * the queue afterward.
178 */
179void blk_freeze_queue(struct request_queue *q)
180{
181 /*
182 * In the !blk_mq case we are only calling this to kill the
183 * q_usage_counter, otherwise this increases the freeze depth
184 * and waits for it to return to zero. For this reason there is
185 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
186 * exported to drivers as the only user for unfreeze is blk_mq.
187 */
188 blk_freeze_queue_start(q);
189 blk_mq_freeze_queue_wait(q);
190}
191
192void blk_mq_freeze_queue(struct request_queue *q)
193{
194 /*
195 * ...just an alias to keep freeze and unfreeze actions balanced
196 * in the blk_mq_* namespace
197 */
198 blk_freeze_queue(q);
199}
200EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
201
202void blk_mq_unfreeze_queue(struct request_queue *q)
203{
204 mutex_lock(&q->mq_freeze_lock);
205 q->mq_freeze_depth--;
206 WARN_ON_ONCE(q->mq_freeze_depth < 0);
207 if (!q->mq_freeze_depth) {
208 percpu_ref_resurrect(&q->q_usage_counter);
209 wake_up_all(&q->mq_freeze_wq);
210 }
211 mutex_unlock(&q->mq_freeze_lock);
212}
213EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
214
215/*
216 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
217 * mpt3sas driver such that this function can be removed.
218 */
219void blk_mq_quiesce_queue_nowait(struct request_queue *q)
220{
221 blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
222}
223EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
224
225/**
226 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
227 * @q: request queue.
228 *
229 * Note: this function does not prevent that the struct request end_io()
230 * callback function is invoked. Once this function is returned, we make
231 * sure no dispatch can happen until the queue is unquiesced via
232 * blk_mq_unquiesce_queue().
233 */
234void blk_mq_quiesce_queue(struct request_queue *q)
235{
236 struct blk_mq_hw_ctx *hctx;
237 unsigned int i;
238 bool rcu = false;
239
240 blk_mq_quiesce_queue_nowait(q);
241
242 queue_for_each_hw_ctx(q, hctx, i) {
243 if (hctx->flags & BLK_MQ_F_BLOCKING)
244 synchronize_srcu(hctx->srcu);
245 else
246 rcu = true;
247 }
248 if (rcu)
249 synchronize_rcu();
250}
251EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
252
253/*
254 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
255 * @q: request queue.
256 *
257 * This function recovers queue into the state before quiescing
258 * which is done by blk_mq_quiesce_queue.
259 */
260void blk_mq_unquiesce_queue(struct request_queue *q)
261{
262 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
263
264 /* dispatch requests which are inserted during quiescing */
265 blk_mq_run_hw_queues(q, true);
266}
267EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
268
269void blk_mq_wake_waiters(struct request_queue *q)
270{
271 struct blk_mq_hw_ctx *hctx;
272 unsigned int i;
273
274 queue_for_each_hw_ctx(q, hctx, i)
275 if (blk_mq_hw_queue_mapped(hctx))
276 blk_mq_tag_wakeup_all(hctx->tags, true);
277}
278
279bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
280{
281 return blk_mq_has_free_tags(hctx->tags);
282}
283EXPORT_SYMBOL(blk_mq_can_queue);
284
285/*
286 * Only need start/end time stamping if we have iostat or
287 * blk stats enabled, or using an IO scheduler.
288 */
289static inline bool blk_mq_need_time_stamp(struct request *rq)
290{
291 return (rq->rq_flags & (RQF_IO_STAT | RQF_STATS)) || rq->q->elevator;
292}
293
294static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
295 unsigned int tag, unsigned int op, u64 alloc_time_ns)
296{
297 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
298 struct request *rq = tags->static_rqs[tag];
299 req_flags_t rq_flags = 0;
300
301 if (data->flags & BLK_MQ_REQ_INTERNAL) {
302 rq->tag = -1;
303 rq->internal_tag = tag;
304 } else {
305 if (data->hctx->flags & BLK_MQ_F_TAG_SHARED) {
306 rq_flags = RQF_MQ_INFLIGHT;
307 atomic_inc(&data->hctx->nr_active);
308 }
309 rq->tag = tag;
310 rq->internal_tag = -1;
311 data->hctx->tags->rqs[rq->tag] = rq;
312 }
313
314 /* csd/requeue_work/fifo_time is initialized before use */
315 rq->q = data->q;
316 rq->mq_ctx = data->ctx;
317 rq->mq_hctx = data->hctx;
318 rq->rq_flags = rq_flags;
319 rq->cmd_flags = op;
320 if (data->flags & BLK_MQ_REQ_PREEMPT)
321 rq->rq_flags |= RQF_PREEMPT;
322 if (blk_queue_io_stat(data->q))
323 rq->rq_flags |= RQF_IO_STAT;
324 INIT_LIST_HEAD(&rq->queuelist);
325 INIT_HLIST_NODE(&rq->hash);
326 RB_CLEAR_NODE(&rq->rb_node);
327 rq->rq_disk = NULL;
328 rq->part = NULL;
329#ifdef CONFIG_BLK_RQ_ALLOC_TIME
330 rq->alloc_time_ns = alloc_time_ns;
331#endif
332 if (blk_mq_need_time_stamp(rq))
333 rq->start_time_ns = ktime_get_ns();
334 else
335 rq->start_time_ns = 0;
336 rq->io_start_time_ns = 0;
337 rq->stats_sectors = 0;
338 rq->nr_phys_segments = 0;
339#if defined(CONFIG_BLK_DEV_INTEGRITY)
340 rq->nr_integrity_segments = 0;
341#endif
342 /* tag was already set */
343 rq->extra_len = 0;
344 WRITE_ONCE(rq->deadline, 0);
345
346 rq->timeout = 0;
347
348 rq->end_io = NULL;
349 rq->end_io_data = NULL;
350
351 data->ctx->rq_dispatched[op_is_sync(op)]++;
352 refcount_set(&rq->ref, 1);
353 return rq;
354}
355
356static struct request *blk_mq_get_request(struct request_queue *q,
357 struct bio *bio,
358 struct blk_mq_alloc_data *data)
359{
360 struct elevator_queue *e = q->elevator;
361 struct request *rq;
362 unsigned int tag;
363 bool clear_ctx_on_error = false;
364 u64 alloc_time_ns = 0;
365
366 blk_queue_enter_live(q);
367
368 /* alloc_time includes depth and tag waits */
369 if (blk_queue_rq_alloc_time(q))
370 alloc_time_ns = ktime_get_ns();
371
372 data->q = q;
373 if (likely(!data->ctx)) {
374 data->ctx = blk_mq_get_ctx(q);
375 clear_ctx_on_error = true;
376 }
377 if (likely(!data->hctx))
378 data->hctx = blk_mq_map_queue(q, data->cmd_flags,
379 data->ctx);
380 if (data->cmd_flags & REQ_NOWAIT)
381 data->flags |= BLK_MQ_REQ_NOWAIT;
382
383 if (e) {
384 data->flags |= BLK_MQ_REQ_INTERNAL;
385
386 /*
387 * Flush requests are special and go directly to the
388 * dispatch list. Don't include reserved tags in the
389 * limiting, as it isn't useful.
390 */
391 if (!op_is_flush(data->cmd_flags) &&
392 e->type->ops.limit_depth &&
393 !(data->flags & BLK_MQ_REQ_RESERVED))
394 e->type->ops.limit_depth(data->cmd_flags, data);
395 } else {
396 blk_mq_tag_busy(data->hctx);
397 }
398
399 tag = blk_mq_get_tag(data);
400 if (tag == BLK_MQ_TAG_FAIL) {
401 if (clear_ctx_on_error)
402 data->ctx = NULL;
403 blk_queue_exit(q);
404 return NULL;
405 }
406
407 rq = blk_mq_rq_ctx_init(data, tag, data->cmd_flags, alloc_time_ns);
408 if (!op_is_flush(data->cmd_flags)) {
409 rq->elv.icq = NULL;
410 if (e && e->type->ops.prepare_request) {
411 if (e->type->icq_cache)
412 blk_mq_sched_assign_ioc(rq);
413
414 e->type->ops.prepare_request(rq, bio);
415 rq->rq_flags |= RQF_ELVPRIV;
416 }
417 }
418 data->hctx->queued++;
419 return rq;
420}
421
422struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
423 blk_mq_req_flags_t flags)
424{
425 struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op };
426 struct request *rq;
427 int ret;
428
429 ret = blk_queue_enter(q, flags);
430 if (ret)
431 return ERR_PTR(ret);
432
433 rq = blk_mq_get_request(q, NULL, &alloc_data);
434 blk_queue_exit(q);
435
436 if (!rq)
437 return ERR_PTR(-EWOULDBLOCK);
438
439 rq->__data_len = 0;
440 rq->__sector = (sector_t) -1;
441 rq->bio = rq->biotail = NULL;
442 return rq;
443}
444EXPORT_SYMBOL(blk_mq_alloc_request);
445
446struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
447 unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
448{
449 struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op };
450 struct request *rq;
451 unsigned int cpu;
452 int ret;
453
454 /*
455 * If the tag allocator sleeps we could get an allocation for a
456 * different hardware context. No need to complicate the low level
457 * allocator for this for the rare use case of a command tied to
458 * a specific queue.
459 */
460 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
461 return ERR_PTR(-EINVAL);
462
463 if (hctx_idx >= q->nr_hw_queues)
464 return ERR_PTR(-EIO);
465
466 ret = blk_queue_enter(q, flags);
467 if (ret)
468 return ERR_PTR(ret);
469
470 /*
471 * Check if the hardware context is actually mapped to anything.
472 * If not tell the caller that it should skip this queue.
473 */
474 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
475 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
476 blk_queue_exit(q);
477 return ERR_PTR(-EXDEV);
478 }
479 cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask);
480 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
481
482 rq = blk_mq_get_request(q, NULL, &alloc_data);
483 blk_queue_exit(q);
484
485 if (!rq)
486 return ERR_PTR(-EWOULDBLOCK);
487
488 return rq;
489}
490EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
491
492static void __blk_mq_free_request(struct request *rq)
493{
494 struct request_queue *q = rq->q;
495 struct blk_mq_ctx *ctx = rq->mq_ctx;
496 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
497 const int sched_tag = rq->internal_tag;
498
499 blk_pm_mark_last_busy(rq);
500 rq->mq_hctx = NULL;
501 if (rq->tag != -1)
502 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
503 if (sched_tag != -1)
504 blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
505 blk_mq_sched_restart(hctx);
506 blk_queue_exit(q);
507}
508
509void blk_mq_free_request(struct request *rq)
510{
511 struct request_queue *q = rq->q;
512 struct elevator_queue *e = q->elevator;
513 struct blk_mq_ctx *ctx = rq->mq_ctx;
514 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
515
516 if (rq->rq_flags & RQF_ELVPRIV) {
517 if (e && e->type->ops.finish_request)
518 e->type->ops.finish_request(rq);
519 if (rq->elv.icq) {
520 put_io_context(rq->elv.icq->ioc);
521 rq->elv.icq = NULL;
522 }
523 }
524
525 ctx->rq_completed[rq_is_sync(rq)]++;
526 if (rq->rq_flags & RQF_MQ_INFLIGHT)
527 atomic_dec(&hctx->nr_active);
528
529 if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
530 laptop_io_completion(q->backing_dev_info);
531
532 rq_qos_done(q, rq);
533
534 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
535 if (refcount_dec_and_test(&rq->ref))
536 __blk_mq_free_request(rq);
537}
538EXPORT_SYMBOL_GPL(blk_mq_free_request);
539
540inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
541{
542 u64 now = 0;
543
544 if (blk_mq_need_time_stamp(rq))
545 now = ktime_get_ns();
546
547 if (rq->rq_flags & RQF_STATS) {
548 blk_mq_poll_stats_start(rq->q);
549 blk_stat_add(rq, now);
550 }
551
552 if (rq->internal_tag != -1)
553 blk_mq_sched_completed_request(rq, now);
554
555 blk_account_io_done(rq, now);
556
557 if (rq->end_io) {
558 rq_qos_done(rq->q, rq);
559 rq->end_io(rq, error);
560 } else {
561 blk_mq_free_request(rq);
562 }
563}
564EXPORT_SYMBOL(__blk_mq_end_request);
565
566void blk_mq_end_request(struct request *rq, blk_status_t error)
567{
568 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
569 BUG();
570 __blk_mq_end_request(rq, error);
571}
572EXPORT_SYMBOL(blk_mq_end_request);
573
574static void __blk_mq_complete_request_remote(void *data)
575{
576 struct request *rq = data;
577 struct request_queue *q = rq->q;
578
579 q->mq_ops->complete(rq);
580}
581
582static void __blk_mq_complete_request(struct request *rq)
583{
584 struct blk_mq_ctx *ctx = rq->mq_ctx;
585 struct request_queue *q = rq->q;
586 bool shared = false;
587 int cpu;
588
589 WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
590 /*
591 * Most of single queue controllers, there is only one irq vector
592 * for handling IO completion, and the only irq's affinity is set
593 * as all possible CPUs. On most of ARCHs, this affinity means the
594 * irq is handled on one specific CPU.
595 *
596 * So complete IO reqeust in softirq context in case of single queue
597 * for not degrading IO performance by irqsoff latency.
598 */
599 if (q->nr_hw_queues == 1) {
600 __blk_complete_request(rq);
601 return;
602 }
603
604 /*
605 * For a polled request, always complete locallly, it's pointless
606 * to redirect the completion.
607 */
608 if ((rq->cmd_flags & REQ_HIPRI) ||
609 !test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) {
610 q->mq_ops->complete(rq);
611 return;
612 }
613
614 cpu = get_cpu();
615 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
616 shared = cpus_share_cache(cpu, ctx->cpu);
617
618 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
619 rq->csd.func = __blk_mq_complete_request_remote;
620 rq->csd.info = rq;
621 rq->csd.flags = 0;
622 smp_call_function_single_async(ctx->cpu, &rq->csd);
623 } else {
624 q->mq_ops->complete(rq);
625 }
626 put_cpu();
627}
628
629static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
630 __releases(hctx->srcu)
631{
632 if (!(hctx->flags & BLK_MQ_F_BLOCKING))
633 rcu_read_unlock();
634 else
635 srcu_read_unlock(hctx->srcu, srcu_idx);
636}
637
638static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
639 __acquires(hctx->srcu)
640{
641 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
642 /* shut up gcc false positive */
643 *srcu_idx = 0;
644 rcu_read_lock();
645 } else
646 *srcu_idx = srcu_read_lock(hctx->srcu);
647}
648
649/**
650 * blk_mq_complete_request - end I/O on a request
651 * @rq: the request being processed
652 *
653 * Description:
654 * Ends all I/O on a request. It does not handle partial completions.
655 * The actual completion happens out-of-order, through a IPI handler.
656 **/
657bool blk_mq_complete_request(struct request *rq)
658{
659 if (unlikely(blk_should_fake_timeout(rq->q)))
660 return false;
661 __blk_mq_complete_request(rq);
662 return true;
663}
664EXPORT_SYMBOL(blk_mq_complete_request);
665
666int blk_mq_request_started(struct request *rq)
667{
668 return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
669}
670EXPORT_SYMBOL_GPL(blk_mq_request_started);
671
672int blk_mq_request_completed(struct request *rq)
673{
674 return blk_mq_rq_state(rq) == MQ_RQ_COMPLETE;
675}
676EXPORT_SYMBOL_GPL(blk_mq_request_completed);
677
678void blk_mq_start_request(struct request *rq)
679{
680 struct request_queue *q = rq->q;
681
682 trace_block_rq_issue(q, rq);
683
684 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
685 rq->io_start_time_ns = ktime_get_ns();
686 rq->stats_sectors = blk_rq_sectors(rq);
687 rq->rq_flags |= RQF_STATS;
688 rq_qos_issue(q, rq);
689 }
690
691 WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
692
693 blk_add_timer(rq);
694 WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT);
695
696 if (q->dma_drain_size && blk_rq_bytes(rq)) {
697 /*
698 * Make sure space for the drain appears. We know we can do
699 * this because max_hw_segments has been adjusted to be one
700 * fewer than the device can handle.
701 */
702 rq->nr_phys_segments++;
703 }
704
705#ifdef CONFIG_BLK_DEV_INTEGRITY
706 if (blk_integrity_rq(rq) && req_op(rq) == REQ_OP_WRITE)
707 q->integrity.profile->prepare_fn(rq);
708#endif
709}
710EXPORT_SYMBOL(blk_mq_start_request);
711
712static void __blk_mq_requeue_request(struct request *rq)
713{
714 struct request_queue *q = rq->q;
715
716 blk_mq_put_driver_tag(rq);
717
718 trace_block_rq_requeue(q, rq);
719 rq_qos_requeue(q, rq);
720
721 if (blk_mq_request_started(rq)) {
722 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
723 rq->rq_flags &= ~RQF_TIMED_OUT;
724 if (q->dma_drain_size && blk_rq_bytes(rq))
725 rq->nr_phys_segments--;
726 }
727}
728
729void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
730{
731 __blk_mq_requeue_request(rq);
732
733 /* this request will be re-inserted to io scheduler queue */
734 blk_mq_sched_requeue_request(rq);
735
736 BUG_ON(!list_empty(&rq->queuelist));
737 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
738}
739EXPORT_SYMBOL(blk_mq_requeue_request);
740
741static void blk_mq_requeue_work(struct work_struct *work)
742{
743 struct request_queue *q =
744 container_of(work, struct request_queue, requeue_work.work);
745 LIST_HEAD(rq_list);
746 struct request *rq, *next;
747
748 spin_lock_irq(&q->requeue_lock);
749 list_splice_init(&q->requeue_list, &rq_list);
750 spin_unlock_irq(&q->requeue_lock);
751
752 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
753 if (!(rq->rq_flags & (RQF_SOFTBARRIER | RQF_DONTPREP)))
754 continue;
755
756 rq->rq_flags &= ~RQF_SOFTBARRIER;
757 list_del_init(&rq->queuelist);
758 /*
759 * If RQF_DONTPREP, rq has contained some driver specific
760 * data, so insert it to hctx dispatch list to avoid any
761 * merge.
762 */
763 if (rq->rq_flags & RQF_DONTPREP)
764 blk_mq_request_bypass_insert(rq, false);
765 else
766 blk_mq_sched_insert_request(rq, true, false, false);
767 }
768
769 while (!list_empty(&rq_list)) {
770 rq = list_entry(rq_list.next, struct request, queuelist);
771 list_del_init(&rq->queuelist);
772 blk_mq_sched_insert_request(rq, false, false, false);
773 }
774
775 blk_mq_run_hw_queues(q, false);
776}
777
778void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
779 bool kick_requeue_list)
780{
781 struct request_queue *q = rq->q;
782 unsigned long flags;
783
784 /*
785 * We abuse this flag that is otherwise used by the I/O scheduler to
786 * request head insertion from the workqueue.
787 */
788 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
789
790 spin_lock_irqsave(&q->requeue_lock, flags);
791 if (at_head) {
792 rq->rq_flags |= RQF_SOFTBARRIER;
793 list_add(&rq->queuelist, &q->requeue_list);
794 } else {
795 list_add_tail(&rq->queuelist, &q->requeue_list);
796 }
797 spin_unlock_irqrestore(&q->requeue_lock, flags);
798
799 if (kick_requeue_list)
800 blk_mq_kick_requeue_list(q);
801}
802
803void blk_mq_kick_requeue_list(struct request_queue *q)
804{
805 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0);
806}
807EXPORT_SYMBOL(blk_mq_kick_requeue_list);
808
809void blk_mq_delay_kick_requeue_list(struct request_queue *q,
810 unsigned long msecs)
811{
812 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
813 msecs_to_jiffies(msecs));
814}
815EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
816
817struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
818{
819 if (tag < tags->nr_tags) {
820 prefetch(tags->rqs[tag]);
821 return tags->rqs[tag];
822 }
823
824 return NULL;
825}
826EXPORT_SYMBOL(blk_mq_tag_to_rq);
827
828static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx *hctx, struct request *rq,
829 void *priv, bool reserved)
830{
831 /*
832 * If we find a request that is inflight and the queue matches,
833 * we know the queue is busy. Return false to stop the iteration.
834 */
835 if (rq->state == MQ_RQ_IN_FLIGHT && rq->q == hctx->queue) {
836 bool *busy = priv;
837
838 *busy = true;
839 return false;
840 }
841
842 return true;
843}
844
845bool blk_mq_queue_inflight(struct request_queue *q)
846{
847 bool busy = false;
848
849 blk_mq_queue_tag_busy_iter(q, blk_mq_rq_inflight, &busy);
850 return busy;
851}
852EXPORT_SYMBOL_GPL(blk_mq_queue_inflight);
853
854static void blk_mq_rq_timed_out(struct request *req, bool reserved)
855{
856 req->rq_flags |= RQF_TIMED_OUT;
857 if (req->q->mq_ops->timeout) {
858 enum blk_eh_timer_return ret;
859
860 ret = req->q->mq_ops->timeout(req, reserved);
861 if (ret == BLK_EH_DONE)
862 return;
863 WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
864 }
865
866 blk_add_timer(req);
867}
868
869static bool blk_mq_req_expired(struct request *rq, unsigned long *next)
870{
871 unsigned long deadline;
872
873 if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT)
874 return false;
875 if (rq->rq_flags & RQF_TIMED_OUT)
876 return false;
877
878 deadline = READ_ONCE(rq->deadline);
879 if (time_after_eq(jiffies, deadline))
880 return true;
881
882 if (*next == 0)
883 *next = deadline;
884 else if (time_after(*next, deadline))
885 *next = deadline;
886 return false;
887}
888
889static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
890 struct request *rq, void *priv, bool reserved)
891{
892 unsigned long *next = priv;
893
894 /*
895 * Just do a quick check if it is expired before locking the request in
896 * so we're not unnecessarilly synchronizing across CPUs.
897 */
898 if (!blk_mq_req_expired(rq, next))
899 return true;
900
901 /*
902 * We have reason to believe the request may be expired. Take a
903 * reference on the request to lock this request lifetime into its
904 * currently allocated context to prevent it from being reallocated in
905 * the event the completion by-passes this timeout handler.
906 *
907 * If the reference was already released, then the driver beat the
908 * timeout handler to posting a natural completion.
909 */
910 if (!refcount_inc_not_zero(&rq->ref))
911 return true;
912
913 /*
914 * The request is now locked and cannot be reallocated underneath the
915 * timeout handler's processing. Re-verify this exact request is truly
916 * expired; if it is not expired, then the request was completed and
917 * reallocated as a new request.
918 */
919 if (blk_mq_req_expired(rq, next))
920 blk_mq_rq_timed_out(rq, reserved);
921
922 if (is_flush_rq(rq, hctx))
923 rq->end_io(rq, 0);
924 else if (refcount_dec_and_test(&rq->ref))
925 __blk_mq_free_request(rq);
926
927 return true;
928}
929
930static void blk_mq_timeout_work(struct work_struct *work)
931{
932 struct request_queue *q =
933 container_of(work, struct request_queue, timeout_work);
934 unsigned long next = 0;
935 struct blk_mq_hw_ctx *hctx;
936 int i;
937
938 /* A deadlock might occur if a request is stuck requiring a
939 * timeout at the same time a queue freeze is waiting
940 * completion, since the timeout code would not be able to
941 * acquire the queue reference here.
942 *
943 * That's why we don't use blk_queue_enter here; instead, we use
944 * percpu_ref_tryget directly, because we need to be able to
945 * obtain a reference even in the short window between the queue
946 * starting to freeze, by dropping the first reference in
947 * blk_freeze_queue_start, and the moment the last request is
948 * consumed, marked by the instant q_usage_counter reaches
949 * zero.
950 */
951 if (!percpu_ref_tryget(&q->q_usage_counter))
952 return;
953
954 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &next);
955
956 if (next != 0) {
957 mod_timer(&q->timeout, next);
958 } else {
959 /*
960 * Request timeouts are handled as a forward rolling timer. If
961 * we end up here it means that no requests are pending and
962 * also that no request has been pending for a while. Mark
963 * each hctx as idle.
964 */
965 queue_for_each_hw_ctx(q, hctx, i) {
966 /* the hctx may be unmapped, so check it here */
967 if (blk_mq_hw_queue_mapped(hctx))
968 blk_mq_tag_idle(hctx);
969 }
970 }
971 blk_queue_exit(q);
972}
973
974struct flush_busy_ctx_data {
975 struct blk_mq_hw_ctx *hctx;
976 struct list_head *list;
977};
978
979static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
980{
981 struct flush_busy_ctx_data *flush_data = data;
982 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
983 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
984 enum hctx_type type = hctx->type;
985
986 spin_lock(&ctx->lock);
987 list_splice_tail_init(&ctx->rq_lists[type], flush_data->list);
988 sbitmap_clear_bit(sb, bitnr);
989 spin_unlock(&ctx->lock);
990 return true;
991}
992
993/*
994 * Process software queues that have been marked busy, splicing them
995 * to the for-dispatch
996 */
997void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
998{
999 struct flush_busy_ctx_data data = {
1000 .hctx = hctx,
1001 .list = list,
1002 };
1003
1004 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
1005}
1006EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
1007
1008struct dispatch_rq_data {
1009 struct blk_mq_hw_ctx *hctx;
1010 struct request *rq;
1011};
1012
1013static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
1014 void *data)
1015{
1016 struct dispatch_rq_data *dispatch_data = data;
1017 struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
1018 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1019 enum hctx_type type = hctx->type;
1020
1021 spin_lock(&ctx->lock);
1022 if (!list_empty(&ctx->rq_lists[type])) {
1023 dispatch_data->rq = list_entry_rq(ctx->rq_lists[type].next);
1024 list_del_init(&dispatch_data->rq->queuelist);
1025 if (list_empty(&ctx->rq_lists[type]))
1026 sbitmap_clear_bit(sb, bitnr);
1027 }
1028 spin_unlock(&ctx->lock);
1029
1030 return !dispatch_data->rq;
1031}
1032
1033struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
1034 struct blk_mq_ctx *start)
1035{
1036 unsigned off = start ? start->index_hw[hctx->type] : 0;
1037 struct dispatch_rq_data data = {
1038 .hctx = hctx,
1039 .rq = NULL,
1040 };
1041
1042 __sbitmap_for_each_set(&hctx->ctx_map, off,
1043 dispatch_rq_from_ctx, &data);
1044
1045 return data.rq;
1046}
1047
1048static inline unsigned int queued_to_index(unsigned int queued)
1049{
1050 if (!queued)
1051 return 0;
1052
1053 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
1054}
1055
1056bool blk_mq_get_driver_tag(struct request *rq)
1057{
1058 struct blk_mq_alloc_data data = {
1059 .q = rq->q,
1060 .hctx = rq->mq_hctx,
1061 .flags = BLK_MQ_REQ_NOWAIT,
1062 .cmd_flags = rq->cmd_flags,
1063 };
1064 bool shared;
1065
1066 if (rq->tag != -1)
1067 goto done;
1068
1069 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
1070 data.flags |= BLK_MQ_REQ_RESERVED;
1071
1072 shared = blk_mq_tag_busy(data.hctx);
1073 rq->tag = blk_mq_get_tag(&data);
1074 if (rq->tag >= 0) {
1075 if (shared) {
1076 rq->rq_flags |= RQF_MQ_INFLIGHT;
1077 atomic_inc(&data.hctx->nr_active);
1078 }
1079 data.hctx->tags->rqs[rq->tag] = rq;
1080 }
1081
1082done:
1083 return rq->tag != -1;
1084}
1085
1086static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
1087 int flags, void *key)
1088{
1089 struct blk_mq_hw_ctx *hctx;
1090
1091 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
1092
1093 spin_lock(&hctx->dispatch_wait_lock);
1094 if (!list_empty(&wait->entry)) {
1095 struct sbitmap_queue *sbq;
1096
1097 list_del_init(&wait->entry);
1098 sbq = &hctx->tags->bitmap_tags;
1099 atomic_dec(&sbq->ws_active);
1100 }
1101 spin_unlock(&hctx->dispatch_wait_lock);
1102
1103 blk_mq_run_hw_queue(hctx, true);
1104 return 1;
1105}
1106
1107/*
1108 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1109 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1110 * restart. For both cases, take care to check the condition again after
1111 * marking us as waiting.
1112 */
1113static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
1114 struct request *rq)
1115{
1116 struct sbitmap_queue *sbq = &hctx->tags->bitmap_tags;
1117 struct wait_queue_head *wq;
1118 wait_queue_entry_t *wait;
1119 bool ret;
1120
1121 if (!(hctx->flags & BLK_MQ_F_TAG_SHARED)) {
1122 blk_mq_sched_mark_restart_hctx(hctx);
1123
1124 /*
1125 * It's possible that a tag was freed in the window between the
1126 * allocation failure and adding the hardware queue to the wait
1127 * queue.
1128 *
1129 * Don't clear RESTART here, someone else could have set it.
1130 * At most this will cost an extra queue run.
1131 */
1132 return blk_mq_get_driver_tag(rq);
1133 }
1134
1135 wait = &hctx->dispatch_wait;
1136 if (!list_empty_careful(&wait->entry))
1137 return false;
1138
1139 wq = &bt_wait_ptr(sbq, hctx)->wait;
1140
1141 spin_lock_irq(&wq->lock);
1142 spin_lock(&hctx->dispatch_wait_lock);
1143 if (!list_empty(&wait->entry)) {
1144 spin_unlock(&hctx->dispatch_wait_lock);
1145 spin_unlock_irq(&wq->lock);
1146 return false;
1147 }
1148
1149 atomic_inc(&sbq->ws_active);
1150 wait->flags &= ~WQ_FLAG_EXCLUSIVE;
1151 __add_wait_queue(wq, wait);
1152
1153 /*
1154 * It's possible that a tag was freed in the window between the
1155 * allocation failure and adding the hardware queue to the wait
1156 * queue.
1157 */
1158 ret = blk_mq_get_driver_tag(rq);
1159 if (!ret) {
1160 spin_unlock(&hctx->dispatch_wait_lock);
1161 spin_unlock_irq(&wq->lock);
1162 return false;
1163 }
1164
1165 /*
1166 * We got a tag, remove ourselves from the wait queue to ensure
1167 * someone else gets the wakeup.
1168 */
1169 list_del_init(&wait->entry);
1170 atomic_dec(&sbq->ws_active);
1171 spin_unlock(&hctx->dispatch_wait_lock);
1172 spin_unlock_irq(&wq->lock);
1173
1174 return true;
1175}
1176
1177#define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1178#define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1179/*
1180 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1181 * - EWMA is one simple way to compute running average value
1182 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1183 * - take 4 as factor for avoiding to get too small(0) result, and this
1184 * factor doesn't matter because EWMA decreases exponentially
1185 */
1186static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy)
1187{
1188 unsigned int ewma;
1189
1190 if (hctx->queue->elevator)
1191 return;
1192
1193 ewma = hctx->dispatch_busy;
1194
1195 if (!ewma && !busy)
1196 return;
1197
1198 ewma *= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT - 1;
1199 if (busy)
1200 ewma += 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR;
1201 ewma /= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT;
1202
1203 hctx->dispatch_busy = ewma;
1204}
1205
1206#define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1207
1208/*
1209 * Returns true if we did some work AND can potentially do more.
1210 */
1211bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
1212 bool got_budget)
1213{
1214 struct blk_mq_hw_ctx *hctx;
1215 struct request *rq, *nxt;
1216 bool no_tag = false;
1217 int errors, queued;
1218 blk_status_t ret = BLK_STS_OK;
1219
1220 if (list_empty(list))
1221 return false;
1222
1223 WARN_ON(!list_is_singular(list) && got_budget);
1224
1225 /*
1226 * Now process all the entries, sending them to the driver.
1227 */
1228 errors = queued = 0;
1229 do {
1230 struct blk_mq_queue_data bd;
1231
1232 rq = list_first_entry(list, struct request, queuelist);
1233
1234 hctx = rq->mq_hctx;
1235 if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
1236 break;
1237
1238 if (!blk_mq_get_driver_tag(rq)) {
1239 /*
1240 * The initial allocation attempt failed, so we need to
1241 * rerun the hardware queue when a tag is freed. The
1242 * waitqueue takes care of that. If the queue is run
1243 * before we add this entry back on the dispatch list,
1244 * we'll re-run it below.
1245 */
1246 if (!blk_mq_mark_tag_wait(hctx, rq)) {
1247 blk_mq_put_dispatch_budget(hctx);
1248 /*
1249 * For non-shared tags, the RESTART check
1250 * will suffice.
1251 */
1252 if (hctx->flags & BLK_MQ_F_TAG_SHARED)
1253 no_tag = true;
1254 break;
1255 }
1256 }
1257
1258 list_del_init(&rq->queuelist);
1259
1260 bd.rq = rq;
1261
1262 /*
1263 * Flag last if we have no more requests, or if we have more
1264 * but can't assign a driver tag to it.
1265 */
1266 if (list_empty(list))
1267 bd.last = true;
1268 else {
1269 nxt = list_first_entry(list, struct request, queuelist);
1270 bd.last = !blk_mq_get_driver_tag(nxt);
1271 }
1272
1273 ret = q->mq_ops->queue_rq(hctx, &bd);
1274 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
1275 /*
1276 * If an I/O scheduler has been configured and we got a
1277 * driver tag for the next request already, free it
1278 * again.
1279 */
1280 if (!list_empty(list)) {
1281 nxt = list_first_entry(list, struct request, queuelist);
1282 blk_mq_put_driver_tag(nxt);
1283 }
1284 list_add(&rq->queuelist, list);
1285 __blk_mq_requeue_request(rq);
1286 break;
1287 }
1288
1289 if (unlikely(ret != BLK_STS_OK)) {
1290 errors++;
1291 blk_mq_end_request(rq, BLK_STS_IOERR);
1292 continue;
1293 }
1294
1295 queued++;
1296 } while (!list_empty(list));
1297
1298 hctx->dispatched[queued_to_index(queued)]++;
1299
1300 /*
1301 * Any items that need requeuing? Stuff them into hctx->dispatch,
1302 * that is where we will continue on next queue run.
1303 */
1304 if (!list_empty(list)) {
1305 bool needs_restart;
1306
1307 /*
1308 * If we didn't flush the entire list, we could have told
1309 * the driver there was more coming, but that turned out to
1310 * be a lie.
1311 */
1312 if (q->mq_ops->commit_rqs)
1313 q->mq_ops->commit_rqs(hctx);
1314
1315 spin_lock(&hctx->lock);
1316 list_splice_init(list, &hctx->dispatch);
1317 spin_unlock(&hctx->lock);
1318
1319 /*
1320 * If SCHED_RESTART was set by the caller of this function and
1321 * it is no longer set that means that it was cleared by another
1322 * thread and hence that a queue rerun is needed.
1323 *
1324 * If 'no_tag' is set, that means that we failed getting
1325 * a driver tag with an I/O scheduler attached. If our dispatch
1326 * waitqueue is no longer active, ensure that we run the queue
1327 * AFTER adding our entries back to the list.
1328 *
1329 * If no I/O scheduler has been configured it is possible that
1330 * the hardware queue got stopped and restarted before requests
1331 * were pushed back onto the dispatch list. Rerun the queue to
1332 * avoid starvation. Notes:
1333 * - blk_mq_run_hw_queue() checks whether or not a queue has
1334 * been stopped before rerunning a queue.
1335 * - Some but not all block drivers stop a queue before
1336 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1337 * and dm-rq.
1338 *
1339 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1340 * bit is set, run queue after a delay to avoid IO stalls
1341 * that could otherwise occur if the queue is idle.
1342 */
1343 needs_restart = blk_mq_sched_needs_restart(hctx);
1344 if (!needs_restart ||
1345 (no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
1346 blk_mq_run_hw_queue(hctx, true);
1347 else if (needs_restart && (ret == BLK_STS_RESOURCE))
1348 blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
1349
1350 blk_mq_update_dispatch_busy(hctx, true);
1351 return false;
1352 } else
1353 blk_mq_update_dispatch_busy(hctx, false);
1354
1355 /*
1356 * If the host/device is unable to accept more work, inform the
1357 * caller of that.
1358 */
1359 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
1360 return false;
1361
1362 return (queued + errors) != 0;
1363}
1364
1365static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1366{
1367 int srcu_idx;
1368
1369 /*
1370 * We should be running this queue from one of the CPUs that
1371 * are mapped to it.
1372 *
1373 * There are at least two related races now between setting
1374 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1375 * __blk_mq_run_hw_queue():
1376 *
1377 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1378 * but later it becomes online, then this warning is harmless
1379 * at all
1380 *
1381 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1382 * but later it becomes offline, then the warning can't be
1383 * triggered, and we depend on blk-mq timeout handler to
1384 * handle dispatched requests to this hctx
1385 */
1386 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1387 cpu_online(hctx->next_cpu)) {
1388 printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
1389 raw_smp_processor_id(),
1390 cpumask_empty(hctx->cpumask) ? "inactive": "active");
1391 dump_stack();
1392 }
1393
1394 /*
1395 * We can't run the queue inline with ints disabled. Ensure that
1396 * we catch bad users of this early.
1397 */
1398 WARN_ON_ONCE(in_interrupt());
1399
1400 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1401
1402 hctx_lock(hctx, &srcu_idx);
1403 blk_mq_sched_dispatch_requests(hctx);
1404 hctx_unlock(hctx, srcu_idx);
1405}
1406
1407static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
1408{
1409 int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
1410
1411 if (cpu >= nr_cpu_ids)
1412 cpu = cpumask_first(hctx->cpumask);
1413 return cpu;
1414}
1415
1416/*
1417 * It'd be great if the workqueue API had a way to pass
1418 * in a mask and had some smarts for more clever placement.
1419 * For now we just round-robin here, switching for every
1420 * BLK_MQ_CPU_WORK_BATCH queued items.
1421 */
1422static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1423{
1424 bool tried = false;
1425 int next_cpu = hctx->next_cpu;
1426
1427 if (hctx->queue->nr_hw_queues == 1)
1428 return WORK_CPU_UNBOUND;
1429
1430 if (--hctx->next_cpu_batch <= 0) {
1431select_cpu:
1432 next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
1433 cpu_online_mask);
1434 if (next_cpu >= nr_cpu_ids)
1435 next_cpu = blk_mq_first_mapped_cpu(hctx);
1436 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1437 }
1438
1439 /*
1440 * Do unbound schedule if we can't find a online CPU for this hctx,
1441 * and it should only happen in the path of handling CPU DEAD.
1442 */
1443 if (!cpu_online(next_cpu)) {
1444 if (!tried) {
1445 tried = true;
1446 goto select_cpu;
1447 }
1448
1449 /*
1450 * Make sure to re-select CPU next time once after CPUs
1451 * in hctx->cpumask become online again.
1452 */
1453 hctx->next_cpu = next_cpu;
1454 hctx->next_cpu_batch = 1;
1455 return WORK_CPU_UNBOUND;
1456 }
1457
1458 hctx->next_cpu = next_cpu;
1459 return next_cpu;
1460}
1461
1462static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1463 unsigned long msecs)
1464{
1465 if (unlikely(blk_mq_hctx_stopped(hctx)))
1466 return;
1467
1468 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1469 int cpu = get_cpu();
1470 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1471 __blk_mq_run_hw_queue(hctx);
1472 put_cpu();
1473 return;
1474 }
1475
1476 put_cpu();
1477 }
1478
1479 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
1480 msecs_to_jiffies(msecs));
1481}
1482
1483void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1484{
1485 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1486}
1487EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1488
1489bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1490{
1491 int srcu_idx;
1492 bool need_run;
1493
1494 /*
1495 * When queue is quiesced, we may be switching io scheduler, or
1496 * updating nr_hw_queues, or other things, and we can't run queue
1497 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1498 *
1499 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1500 * quiesced.
1501 */
1502 hctx_lock(hctx, &srcu_idx);
1503 need_run = !blk_queue_quiesced(hctx->queue) &&
1504 blk_mq_hctx_has_pending(hctx);
1505 hctx_unlock(hctx, srcu_idx);
1506
1507 if (need_run) {
1508 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1509 return true;
1510 }
1511
1512 return false;
1513}
1514EXPORT_SYMBOL(blk_mq_run_hw_queue);
1515
1516void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1517{
1518 struct blk_mq_hw_ctx *hctx;
1519 int i;
1520
1521 queue_for_each_hw_ctx(q, hctx, i) {
1522 if (blk_mq_hctx_stopped(hctx))
1523 continue;
1524
1525 blk_mq_run_hw_queue(hctx, async);
1526 }
1527}
1528EXPORT_SYMBOL(blk_mq_run_hw_queues);
1529
1530/**
1531 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1532 * @q: request queue.
1533 *
1534 * The caller is responsible for serializing this function against
1535 * blk_mq_{start,stop}_hw_queue().
1536 */
1537bool blk_mq_queue_stopped(struct request_queue *q)
1538{
1539 struct blk_mq_hw_ctx *hctx;
1540 int i;
1541
1542 queue_for_each_hw_ctx(q, hctx, i)
1543 if (blk_mq_hctx_stopped(hctx))
1544 return true;
1545
1546 return false;
1547}
1548EXPORT_SYMBOL(blk_mq_queue_stopped);
1549
1550/*
1551 * This function is often used for pausing .queue_rq() by driver when
1552 * there isn't enough resource or some conditions aren't satisfied, and
1553 * BLK_STS_RESOURCE is usually returned.
1554 *
1555 * We do not guarantee that dispatch can be drained or blocked
1556 * after blk_mq_stop_hw_queue() returns. Please use
1557 * blk_mq_quiesce_queue() for that requirement.
1558 */
1559void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1560{
1561 cancel_delayed_work(&hctx->run_work);
1562
1563 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1564}
1565EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1566
1567/*
1568 * This function is often used for pausing .queue_rq() by driver when
1569 * there isn't enough resource or some conditions aren't satisfied, and
1570 * BLK_STS_RESOURCE is usually returned.
1571 *
1572 * We do not guarantee that dispatch can be drained or blocked
1573 * after blk_mq_stop_hw_queues() returns. Please use
1574 * blk_mq_quiesce_queue() for that requirement.
1575 */
1576void blk_mq_stop_hw_queues(struct request_queue *q)
1577{
1578 struct blk_mq_hw_ctx *hctx;
1579 int i;
1580
1581 queue_for_each_hw_ctx(q, hctx, i)
1582 blk_mq_stop_hw_queue(hctx);
1583}
1584EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1585
1586void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1587{
1588 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1589
1590 blk_mq_run_hw_queue(hctx, false);
1591}
1592EXPORT_SYMBOL(blk_mq_start_hw_queue);
1593
1594void blk_mq_start_hw_queues(struct request_queue *q)
1595{
1596 struct blk_mq_hw_ctx *hctx;
1597 int i;
1598
1599 queue_for_each_hw_ctx(q, hctx, i)
1600 blk_mq_start_hw_queue(hctx);
1601}
1602EXPORT_SYMBOL(blk_mq_start_hw_queues);
1603
1604void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1605{
1606 if (!blk_mq_hctx_stopped(hctx))
1607 return;
1608
1609 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1610 blk_mq_run_hw_queue(hctx, async);
1611}
1612EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1613
1614void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1615{
1616 struct blk_mq_hw_ctx *hctx;
1617 int i;
1618
1619 queue_for_each_hw_ctx(q, hctx, i)
1620 blk_mq_start_stopped_hw_queue(hctx, async);
1621}
1622EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1623
1624static void blk_mq_run_work_fn(struct work_struct *work)
1625{
1626 struct blk_mq_hw_ctx *hctx;
1627
1628 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1629
1630 /*
1631 * If we are stopped, don't run the queue.
1632 */
1633 if (test_bit(BLK_MQ_S_STOPPED, &hctx->state))
1634 return;
1635
1636 __blk_mq_run_hw_queue(hctx);
1637}
1638
1639static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1640 struct request *rq,
1641 bool at_head)
1642{
1643 struct blk_mq_ctx *ctx = rq->mq_ctx;
1644 enum hctx_type type = hctx->type;
1645
1646 lockdep_assert_held(&ctx->lock);
1647
1648 trace_block_rq_insert(hctx->queue, rq);
1649
1650 if (at_head)
1651 list_add(&rq->queuelist, &ctx->rq_lists[type]);
1652 else
1653 list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
1654}
1655
1656void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1657 bool at_head)
1658{
1659 struct blk_mq_ctx *ctx = rq->mq_ctx;
1660
1661 lockdep_assert_held(&ctx->lock);
1662
1663 __blk_mq_insert_req_list(hctx, rq, at_head);
1664 blk_mq_hctx_mark_pending(hctx, ctx);
1665}
1666
1667/*
1668 * Should only be used carefully, when the caller knows we want to
1669 * bypass a potential IO scheduler on the target device.
1670 */
1671void blk_mq_request_bypass_insert(struct request *rq, bool run_queue)
1672{
1673 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1674
1675 spin_lock(&hctx->lock);
1676 list_add_tail(&rq->queuelist, &hctx->dispatch);
1677 spin_unlock(&hctx->lock);
1678
1679 if (run_queue)
1680 blk_mq_run_hw_queue(hctx, false);
1681}
1682
1683void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1684 struct list_head *list)
1685
1686{
1687 struct request *rq;
1688 enum hctx_type type = hctx->type;
1689
1690 /*
1691 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1692 * offline now
1693 */
1694 list_for_each_entry(rq, list, queuelist) {
1695 BUG_ON(rq->mq_ctx != ctx);
1696 trace_block_rq_insert(hctx->queue, rq);
1697 }
1698
1699 spin_lock(&ctx->lock);
1700 list_splice_tail_init(list, &ctx->rq_lists[type]);
1701 blk_mq_hctx_mark_pending(hctx, ctx);
1702 spin_unlock(&ctx->lock);
1703}
1704
1705static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
1706{
1707 struct request *rqa = container_of(a, struct request, queuelist);
1708 struct request *rqb = container_of(b, struct request, queuelist);
1709
1710 if (rqa->mq_ctx < rqb->mq_ctx)
1711 return -1;
1712 else if (rqa->mq_ctx > rqb->mq_ctx)
1713 return 1;
1714 else if (rqa->mq_hctx < rqb->mq_hctx)
1715 return -1;
1716 else if (rqa->mq_hctx > rqb->mq_hctx)
1717 return 1;
1718
1719 return blk_rq_pos(rqa) > blk_rq_pos(rqb);
1720}
1721
1722void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1723{
1724 struct blk_mq_hw_ctx *this_hctx;
1725 struct blk_mq_ctx *this_ctx;
1726 struct request_queue *this_q;
1727 struct request *rq;
1728 LIST_HEAD(list);
1729 LIST_HEAD(rq_list);
1730 unsigned int depth;
1731
1732 list_splice_init(&plug->mq_list, &list);
1733
1734 if (plug->rq_count > 2 && plug->multiple_queues)
1735 list_sort(NULL, &list, plug_rq_cmp);
1736
1737 plug->rq_count = 0;
1738
1739 this_q = NULL;
1740 this_hctx = NULL;
1741 this_ctx = NULL;
1742 depth = 0;
1743
1744 while (!list_empty(&list)) {
1745 rq = list_entry_rq(list.next);
1746 list_del_init(&rq->queuelist);
1747 BUG_ON(!rq->q);
1748 if (rq->mq_hctx != this_hctx || rq->mq_ctx != this_ctx) {
1749 if (this_hctx) {
1750 trace_block_unplug(this_q, depth, !from_schedule);
1751 blk_mq_sched_insert_requests(this_hctx, this_ctx,
1752 &rq_list,
1753 from_schedule);
1754 }
1755
1756 this_q = rq->q;
1757 this_ctx = rq->mq_ctx;
1758 this_hctx = rq->mq_hctx;
1759 depth = 0;
1760 }
1761
1762 depth++;
1763 list_add_tail(&rq->queuelist, &rq_list);
1764 }
1765
1766 /*
1767 * If 'this_hctx' is set, we know we have entries to complete
1768 * on 'rq_list'. Do those.
1769 */
1770 if (this_hctx) {
1771 trace_block_unplug(this_q, depth, !from_schedule);
1772 blk_mq_sched_insert_requests(this_hctx, this_ctx, &rq_list,
1773 from_schedule);
1774 }
1775}
1776
1777static void blk_mq_bio_to_request(struct request *rq, struct bio *bio,
1778 unsigned int nr_segs)
1779{
1780 if (bio->bi_opf & REQ_RAHEAD)
1781 rq->cmd_flags |= REQ_FAILFAST_MASK;
1782
1783 rq->__sector = bio->bi_iter.bi_sector;
1784 rq->write_hint = bio->bi_write_hint;
1785 blk_rq_bio_prep(rq, bio, nr_segs);
1786
1787 blk_account_io_start(rq, true);
1788}
1789
1790static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
1791 struct request *rq,
1792 blk_qc_t *cookie, bool last)
1793{
1794 struct request_queue *q = rq->q;
1795 struct blk_mq_queue_data bd = {
1796 .rq = rq,
1797 .last = last,
1798 };
1799 blk_qc_t new_cookie;
1800 blk_status_t ret;
1801
1802 new_cookie = request_to_qc_t(hctx, rq);
1803
1804 /*
1805 * For OK queue, we are done. For error, caller may kill it.
1806 * Any other error (busy), just add it to our list as we
1807 * previously would have done.
1808 */
1809 ret = q->mq_ops->queue_rq(hctx, &bd);
1810 switch (ret) {
1811 case BLK_STS_OK:
1812 blk_mq_update_dispatch_busy(hctx, false);
1813 *cookie = new_cookie;
1814 break;
1815 case BLK_STS_RESOURCE:
1816 case BLK_STS_DEV_RESOURCE:
1817 blk_mq_update_dispatch_busy(hctx, true);
1818 __blk_mq_requeue_request(rq);
1819 break;
1820 default:
1821 blk_mq_update_dispatch_busy(hctx, false);
1822 *cookie = BLK_QC_T_NONE;
1823 break;
1824 }
1825
1826 return ret;
1827}
1828
1829static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1830 struct request *rq,
1831 blk_qc_t *cookie,
1832 bool bypass_insert, bool last)
1833{
1834 struct request_queue *q = rq->q;
1835 bool run_queue = true;
1836
1837 /*
1838 * RCU or SRCU read lock is needed before checking quiesced flag.
1839 *
1840 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1841 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1842 * and avoid driver to try to dispatch again.
1843 */
1844 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
1845 run_queue = false;
1846 bypass_insert = false;
1847 goto insert;
1848 }
1849
1850 if (q->elevator && !bypass_insert)
1851 goto insert;
1852
1853 if (!blk_mq_get_dispatch_budget(hctx))
1854 goto insert;
1855
1856 if (!blk_mq_get_driver_tag(rq)) {
1857 blk_mq_put_dispatch_budget(hctx);
1858 goto insert;
1859 }
1860
1861 return __blk_mq_issue_directly(hctx, rq, cookie, last);
1862insert:
1863 if (bypass_insert)
1864 return BLK_STS_RESOURCE;
1865
1866 blk_mq_request_bypass_insert(rq, run_queue);
1867 return BLK_STS_OK;
1868}
1869
1870static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1871 struct request *rq, blk_qc_t *cookie)
1872{
1873 blk_status_t ret;
1874 int srcu_idx;
1875
1876 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1877
1878 hctx_lock(hctx, &srcu_idx);
1879
1880 ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false, true);
1881 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
1882 blk_mq_request_bypass_insert(rq, true);
1883 else if (ret != BLK_STS_OK)
1884 blk_mq_end_request(rq, ret);
1885
1886 hctx_unlock(hctx, srcu_idx);
1887}
1888
1889blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
1890{
1891 blk_status_t ret;
1892 int srcu_idx;
1893 blk_qc_t unused_cookie;
1894 struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
1895
1896 hctx_lock(hctx, &srcu_idx);
1897 ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true, last);
1898 hctx_unlock(hctx, srcu_idx);
1899
1900 return ret;
1901}
1902
1903void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
1904 struct list_head *list)
1905{
1906 while (!list_empty(list)) {
1907 blk_status_t ret;
1908 struct request *rq = list_first_entry(list, struct request,
1909 queuelist);
1910
1911 list_del_init(&rq->queuelist);
1912 ret = blk_mq_request_issue_directly(rq, list_empty(list));
1913 if (ret != BLK_STS_OK) {
1914 if (ret == BLK_STS_RESOURCE ||
1915 ret == BLK_STS_DEV_RESOURCE) {
1916 blk_mq_request_bypass_insert(rq,
1917 list_empty(list));
1918 break;
1919 }
1920 blk_mq_end_request(rq, ret);
1921 }
1922 }
1923
1924 /*
1925 * If we didn't flush the entire list, we could have told
1926 * the driver there was more coming, but that turned out to
1927 * be a lie.
1928 */
1929 if (!list_empty(list) && hctx->queue->mq_ops->commit_rqs)
1930 hctx->queue->mq_ops->commit_rqs(hctx);
1931}
1932
1933static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
1934{
1935 list_add_tail(&rq->queuelist, &plug->mq_list);
1936 plug->rq_count++;
1937 if (!plug->multiple_queues && !list_is_singular(&plug->mq_list)) {
1938 struct request *tmp;
1939
1940 tmp = list_first_entry(&plug->mq_list, struct request,
1941 queuelist);
1942 if (tmp->q != rq->q)
1943 plug->multiple_queues = true;
1944 }
1945}
1946
1947static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1948{
1949 const int is_sync = op_is_sync(bio->bi_opf);
1950 const int is_flush_fua = op_is_flush(bio->bi_opf);
1951 struct blk_mq_alloc_data data = { .flags = 0};
1952 struct request *rq;
1953 struct blk_plug *plug;
1954 struct request *same_queue_rq = NULL;
1955 unsigned int nr_segs;
1956 blk_qc_t cookie;
1957
1958 blk_queue_bounce(q, &bio);
1959 __blk_queue_split(q, &bio, &nr_segs);
1960
1961 if (!bio_integrity_prep(bio))
1962 return BLK_QC_T_NONE;
1963
1964 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1965 blk_attempt_plug_merge(q, bio, nr_segs, &same_queue_rq))
1966 return BLK_QC_T_NONE;
1967
1968 if (blk_mq_sched_bio_merge(q, bio, nr_segs))
1969 return BLK_QC_T_NONE;
1970
1971 rq_qos_throttle(q, bio);
1972
1973 data.cmd_flags = bio->bi_opf;
1974 rq = blk_mq_get_request(q, bio, &data);
1975 if (unlikely(!rq)) {
1976 rq_qos_cleanup(q, bio);
1977 if (bio->bi_opf & REQ_NOWAIT)
1978 bio_wouldblock_error(bio);
1979 return BLK_QC_T_NONE;
1980 }
1981
1982 trace_block_getrq(q, bio, bio->bi_opf);
1983
1984 rq_qos_track(q, rq, bio);
1985
1986 cookie = request_to_qc_t(data.hctx, rq);
1987
1988 blk_mq_bio_to_request(rq, bio, nr_segs);
1989
1990 plug = blk_mq_plug(q, bio);
1991 if (unlikely(is_flush_fua)) {
1992 /* bypass scheduler for flush rq */
1993 blk_insert_flush(rq);
1994 blk_mq_run_hw_queue(data.hctx, true);
1995 } else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs ||
1996 !blk_queue_nonrot(q))) {
1997 /*
1998 * Use plugging if we have a ->commit_rqs() hook as well, as
1999 * we know the driver uses bd->last in a smart fashion.
2000 *
2001 * Use normal plugging if this disk is slow HDD, as sequential
2002 * IO may benefit a lot from plug merging.
2003 */
2004 unsigned int request_count = plug->rq_count;
2005 struct request *last = NULL;
2006
2007 if (!request_count)
2008 trace_block_plug(q);
2009 else
2010 last = list_entry_rq(plug->mq_list.prev);
2011
2012 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
2013 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
2014 blk_flush_plug_list(plug, false);
2015 trace_block_plug(q);
2016 }
2017
2018 blk_add_rq_to_plug(plug, rq);
2019 } else if (q->elevator) {
2020 blk_mq_sched_insert_request(rq, false, true, true);
2021 } else if (plug && !blk_queue_nomerges(q)) {
2022 /*
2023 * We do limited plugging. If the bio can be merged, do that.
2024 * Otherwise the existing request in the plug list will be
2025 * issued. So the plug list will have one request at most
2026 * The plug list might get flushed before this. If that happens,
2027 * the plug list is empty, and same_queue_rq is invalid.
2028 */
2029 if (list_empty(&plug->mq_list))
2030 same_queue_rq = NULL;
2031 if (same_queue_rq) {
2032 list_del_init(&same_queue_rq->queuelist);
2033 plug->rq_count--;
2034 }
2035 blk_add_rq_to_plug(plug, rq);
2036 trace_block_plug(q);
2037
2038 if (same_queue_rq) {
2039 data.hctx = same_queue_rq->mq_hctx;
2040 trace_block_unplug(q, 1, true);
2041 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
2042 &cookie);
2043 }
2044 } else if ((q->nr_hw_queues > 1 && is_sync) ||
2045 !data.hctx->dispatch_busy) {
2046 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
2047 } else {
2048 blk_mq_sched_insert_request(rq, false, true, true);
2049 }
2050
2051 return cookie;
2052}
2053
2054void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2055 unsigned int hctx_idx)
2056{
2057 struct page *page;
2058
2059 if (tags->rqs && set->ops->exit_request) {
2060 int i;
2061
2062 for (i = 0; i < tags->nr_tags; i++) {
2063 struct request *rq = tags->static_rqs[i];
2064
2065 if (!rq)
2066 continue;
2067 set->ops->exit_request(set, rq, hctx_idx);
2068 tags->static_rqs[i] = NULL;
2069 }
2070 }
2071
2072 while (!list_empty(&tags->page_list)) {
2073 page = list_first_entry(&tags->page_list, struct page, lru);
2074 list_del_init(&page->lru);
2075 /*
2076 * Remove kmemleak object previously allocated in
2077 * blk_mq_alloc_rqs().
2078 */
2079 kmemleak_free(page_address(page));
2080 __free_pages(page, page->private);
2081 }
2082}
2083
2084void blk_mq_free_rq_map(struct blk_mq_tags *tags)
2085{
2086 kfree(tags->rqs);
2087 tags->rqs = NULL;
2088 kfree(tags->static_rqs);
2089 tags->static_rqs = NULL;
2090
2091 blk_mq_free_tags(tags);
2092}
2093
2094struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
2095 unsigned int hctx_idx,
2096 unsigned int nr_tags,
2097 unsigned int reserved_tags)
2098{
2099 struct blk_mq_tags *tags;
2100 int node;
2101
2102 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2103 if (node == NUMA_NO_NODE)
2104 node = set->numa_node;
2105
2106 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
2107 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
2108 if (!tags)
2109 return NULL;
2110
2111 tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2112 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2113 node);
2114 if (!tags->rqs) {
2115 blk_mq_free_tags(tags);
2116 return NULL;
2117 }
2118
2119 tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *),
2120 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2121 node);
2122 if (!tags->static_rqs) {
2123 kfree(tags->rqs);
2124 blk_mq_free_tags(tags);
2125 return NULL;
2126 }
2127
2128 return tags;
2129}
2130
2131static size_t order_to_size(unsigned int order)
2132{
2133 return (size_t)PAGE_SIZE << order;
2134}
2135
2136static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
2137 unsigned int hctx_idx, int node)
2138{
2139 int ret;
2140
2141 if (set->ops->init_request) {
2142 ret = set->ops->init_request(set, rq, hctx_idx, node);
2143 if (ret)
2144 return ret;
2145 }
2146
2147 WRITE_ONCE(rq->state, MQ_RQ_IDLE);
2148 return 0;
2149}
2150
2151int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2152 unsigned int hctx_idx, unsigned int depth)
2153{
2154 unsigned int i, j, entries_per_page, max_order = 4;
2155 size_t rq_size, left;
2156 int node;
2157
2158 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], hctx_idx);
2159 if (node == NUMA_NO_NODE)
2160 node = set->numa_node;
2161
2162 INIT_LIST_HEAD(&tags->page_list);
2163
2164 /*
2165 * rq_size is the size of the request plus driver payload, rounded
2166 * to the cacheline size
2167 */
2168 rq_size = round_up(sizeof(struct request) + set->cmd_size,
2169 cache_line_size());
2170 left = rq_size * depth;
2171
2172 for (i = 0; i < depth; ) {
2173 int this_order = max_order;
2174 struct page *page;
2175 int to_do;
2176 void *p;
2177
2178 while (this_order && left < order_to_size(this_order - 1))
2179 this_order--;
2180
2181 do {
2182 page = alloc_pages_node(node,
2183 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
2184 this_order);
2185 if (page)
2186 break;
2187 if (!this_order--)
2188 break;
2189 if (order_to_size(this_order) < rq_size)
2190 break;
2191 } while (1);
2192
2193 if (!page)
2194 goto fail;
2195
2196 page->private = this_order;
2197 list_add_tail(&page->lru, &tags->page_list);
2198
2199 p = page_address(page);
2200 /*
2201 * Allow kmemleak to scan these pages as they contain pointers
2202 * to additional allocations like via ops->init_request().
2203 */
2204 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
2205 entries_per_page = order_to_size(this_order) / rq_size;
2206 to_do = min(entries_per_page, depth - i);
2207 left -= to_do * rq_size;
2208 for (j = 0; j < to_do; j++) {
2209 struct request *rq = p;
2210
2211 tags->static_rqs[i] = rq;
2212 if (blk_mq_init_request(set, rq, hctx_idx, node)) {
2213 tags->static_rqs[i] = NULL;
2214 goto fail;
2215 }
2216
2217 p += rq_size;
2218 i++;
2219 }
2220 }
2221 return 0;
2222
2223fail:
2224 blk_mq_free_rqs(set, tags, hctx_idx);
2225 return -ENOMEM;
2226}
2227
2228/*
2229 * 'cpu' is going away. splice any existing rq_list entries from this
2230 * software queue to the hw queue dispatch list, and ensure that it
2231 * gets run.
2232 */
2233static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
2234{
2235 struct blk_mq_hw_ctx *hctx;
2236 struct blk_mq_ctx *ctx;
2237 LIST_HEAD(tmp);
2238 enum hctx_type type;
2239
2240 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
2241 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
2242 type = hctx->type;
2243
2244 spin_lock(&ctx->lock);
2245 if (!list_empty(&ctx->rq_lists[type])) {
2246 list_splice_init(&ctx->rq_lists[type], &tmp);
2247 blk_mq_hctx_clear_pending(hctx, ctx);
2248 }
2249 spin_unlock(&ctx->lock);
2250
2251 if (list_empty(&tmp))
2252 return 0;
2253
2254 spin_lock(&hctx->lock);
2255 list_splice_tail_init(&tmp, &hctx->dispatch);
2256 spin_unlock(&hctx->lock);
2257
2258 blk_mq_run_hw_queue(hctx, true);
2259 return 0;
2260}
2261
2262static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
2263{
2264 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
2265 &hctx->cpuhp_dead);
2266}
2267
2268/* hctx->ctxs will be freed in queue's release handler */
2269static void blk_mq_exit_hctx(struct request_queue *q,
2270 struct blk_mq_tag_set *set,
2271 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
2272{
2273 if (blk_mq_hw_queue_mapped(hctx))
2274 blk_mq_tag_idle(hctx);
2275
2276 if (set->ops->exit_request)
2277 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
2278
2279 if (set->ops->exit_hctx)
2280 set->ops->exit_hctx(hctx, hctx_idx);
2281
2282 blk_mq_remove_cpuhp(hctx);
2283
2284 spin_lock(&q->unused_hctx_lock);
2285 list_add(&hctx->hctx_list, &q->unused_hctx_list);
2286 spin_unlock(&q->unused_hctx_lock);
2287}
2288
2289static void blk_mq_exit_hw_queues(struct request_queue *q,
2290 struct blk_mq_tag_set *set, int nr_queue)
2291{
2292 struct blk_mq_hw_ctx *hctx;
2293 unsigned int i;
2294
2295 queue_for_each_hw_ctx(q, hctx, i) {
2296 if (i == nr_queue)
2297 break;
2298 blk_mq_debugfs_unregister_hctx(hctx);
2299 blk_mq_exit_hctx(q, set, hctx, i);
2300 }
2301}
2302
2303static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2304{
2305 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2306
2307 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
2308 __alignof__(struct blk_mq_hw_ctx)) !=
2309 sizeof(struct blk_mq_hw_ctx));
2310
2311 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2312 hw_ctx_size += sizeof(struct srcu_struct);
2313
2314 return hw_ctx_size;
2315}
2316
2317static int blk_mq_init_hctx(struct request_queue *q,
2318 struct blk_mq_tag_set *set,
2319 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
2320{
2321 hctx->queue_num = hctx_idx;
2322
2323 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
2324
2325 hctx->tags = set->tags[hctx_idx];
2326
2327 if (set->ops->init_hctx &&
2328 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2329 goto unregister_cpu_notifier;
2330
2331 if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
2332 hctx->numa_node))
2333 goto exit_hctx;
2334 return 0;
2335
2336 exit_hctx:
2337 if (set->ops->exit_hctx)
2338 set->ops->exit_hctx(hctx, hctx_idx);
2339 unregister_cpu_notifier:
2340 blk_mq_remove_cpuhp(hctx);
2341 return -1;
2342}
2343
2344static struct blk_mq_hw_ctx *
2345blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
2346 int node)
2347{
2348 struct blk_mq_hw_ctx *hctx;
2349 gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
2350
2351 hctx = kzalloc_node(blk_mq_hw_ctx_size(set), gfp, node);
2352 if (!hctx)
2353 goto fail_alloc_hctx;
2354
2355 if (!zalloc_cpumask_var_node(&hctx->cpumask, gfp, node))
2356 goto free_hctx;
2357
2358 atomic_set(&hctx->nr_active, 0);
2359 if (node == NUMA_NO_NODE)
2360 node = set->numa_node;
2361 hctx->numa_node = node;
2362
2363 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
2364 spin_lock_init(&hctx->lock);
2365 INIT_LIST_HEAD(&hctx->dispatch);
2366 hctx->queue = q;
2367 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
2368
2369 INIT_LIST_HEAD(&hctx->hctx_list);
2370
2371 /*
2372 * Allocate space for all possible cpus to avoid allocation at
2373 * runtime
2374 */
2375 hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
2376 gfp, node);
2377 if (!hctx->ctxs)
2378 goto free_cpumask;
2379
2380 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
2381 gfp, node))
2382 goto free_ctxs;
2383 hctx->nr_ctx = 0;
2384
2385 spin_lock_init(&hctx->dispatch_wait_lock);
2386 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
2387 INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
2388
2389 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size,
2390 gfp);
2391 if (!hctx->fq)
2392 goto free_bitmap;
2393
2394 if (hctx->flags & BLK_MQ_F_BLOCKING)
2395 init_srcu_struct(hctx->srcu);
2396 blk_mq_hctx_kobj_init(hctx);
2397
2398 return hctx;
2399
2400 free_bitmap:
2401 sbitmap_free(&hctx->ctx_map);
2402 free_ctxs:
2403 kfree(hctx->ctxs);
2404 free_cpumask:
2405 free_cpumask_var(hctx->cpumask);
2406 free_hctx:
2407 kfree(hctx);
2408 fail_alloc_hctx:
2409 return NULL;
2410}
2411
2412static void blk_mq_init_cpu_queues(struct request_queue *q,
2413 unsigned int nr_hw_queues)
2414{
2415 struct blk_mq_tag_set *set = q->tag_set;
2416 unsigned int i, j;
2417
2418 for_each_possible_cpu(i) {
2419 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2420 struct blk_mq_hw_ctx *hctx;
2421 int k;
2422
2423 __ctx->cpu = i;
2424 spin_lock_init(&__ctx->lock);
2425 for (k = HCTX_TYPE_DEFAULT; k < HCTX_MAX_TYPES; k++)
2426 INIT_LIST_HEAD(&__ctx->rq_lists[k]);
2427
2428 __ctx->queue = q;
2429
2430 /*
2431 * Set local node, IFF we have more than one hw queue. If
2432 * not, we remain on the home node of the device
2433 */
2434 for (j = 0; j < set->nr_maps; j++) {
2435 hctx = blk_mq_map_queue_type(q, j, i);
2436 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2437 hctx->numa_node = local_memory_node(cpu_to_node(i));
2438 }
2439 }
2440}
2441
2442static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2443{
2444 int ret = 0;
2445
2446 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2447 set->queue_depth, set->reserved_tags);
2448 if (!set->tags[hctx_idx])
2449 return false;
2450
2451 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2452 set->queue_depth);
2453 if (!ret)
2454 return true;
2455
2456 blk_mq_free_rq_map(set->tags[hctx_idx]);
2457 set->tags[hctx_idx] = NULL;
2458 return false;
2459}
2460
2461static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2462 unsigned int hctx_idx)
2463{
2464 if (set->tags && set->tags[hctx_idx]) {
2465 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2466 blk_mq_free_rq_map(set->tags[hctx_idx]);
2467 set->tags[hctx_idx] = NULL;
2468 }
2469}
2470
2471static void blk_mq_map_swqueue(struct request_queue *q)
2472{
2473 unsigned int i, j, hctx_idx;
2474 struct blk_mq_hw_ctx *hctx;
2475 struct blk_mq_ctx *ctx;
2476 struct blk_mq_tag_set *set = q->tag_set;
2477
2478 queue_for_each_hw_ctx(q, hctx, i) {
2479 cpumask_clear(hctx->cpumask);
2480 hctx->nr_ctx = 0;
2481 hctx->dispatch_from = NULL;
2482 }
2483
2484 /*
2485 * Map software to hardware queues.
2486 *
2487 * If the cpu isn't present, the cpu is mapped to first hctx.
2488 */
2489 for_each_possible_cpu(i) {
2490 hctx_idx = set->map[HCTX_TYPE_DEFAULT].mq_map[i];
2491 /* unmapped hw queue can be remapped after CPU topo changed */
2492 if (!set->tags[hctx_idx] &&
2493 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2494 /*
2495 * If tags initialization fail for some hctx,
2496 * that hctx won't be brought online. In this
2497 * case, remap the current ctx to hctx[0] which
2498 * is guaranteed to always have tags allocated
2499 */
2500 set->map[HCTX_TYPE_DEFAULT].mq_map[i] = 0;
2501 }
2502
2503 ctx = per_cpu_ptr(q->queue_ctx, i);
2504 for (j = 0; j < set->nr_maps; j++) {
2505 if (!set->map[j].nr_queues) {
2506 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2507 HCTX_TYPE_DEFAULT, i);
2508 continue;
2509 }
2510
2511 hctx = blk_mq_map_queue_type(q, j, i);
2512 ctx->hctxs[j] = hctx;
2513 /*
2514 * If the CPU is already set in the mask, then we've
2515 * mapped this one already. This can happen if
2516 * devices share queues across queue maps.
2517 */
2518 if (cpumask_test_cpu(i, hctx->cpumask))
2519 continue;
2520
2521 cpumask_set_cpu(i, hctx->cpumask);
2522 hctx->type = j;
2523 ctx->index_hw[hctx->type] = hctx->nr_ctx;
2524 hctx->ctxs[hctx->nr_ctx++] = ctx;
2525
2526 /*
2527 * If the nr_ctx type overflows, we have exceeded the
2528 * amount of sw queues we can support.
2529 */
2530 BUG_ON(!hctx->nr_ctx);
2531 }
2532
2533 for (; j < HCTX_MAX_TYPES; j++)
2534 ctx->hctxs[j] = blk_mq_map_queue_type(q,
2535 HCTX_TYPE_DEFAULT, i);
2536 }
2537
2538 queue_for_each_hw_ctx(q, hctx, i) {
2539 /*
2540 * If no software queues are mapped to this hardware queue,
2541 * disable it and free the request entries.
2542 */
2543 if (!hctx->nr_ctx) {
2544 /* Never unmap queue 0. We need it as a
2545 * fallback in case of a new remap fails
2546 * allocation
2547 */
2548 if (i && set->tags[i])
2549 blk_mq_free_map_and_requests(set, i);
2550
2551 hctx->tags = NULL;
2552 continue;
2553 }
2554
2555 hctx->tags = set->tags[i];
2556 WARN_ON(!hctx->tags);
2557
2558 /*
2559 * Set the map size to the number of mapped software queues.
2560 * This is more accurate and more efficient than looping
2561 * over all possibly mapped software queues.
2562 */
2563 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2564
2565 /*
2566 * Initialize batch roundrobin counts
2567 */
2568 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
2569 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2570 }
2571}
2572
2573/*
2574 * Caller needs to ensure that we're either frozen/quiesced, or that
2575 * the queue isn't live yet.
2576 */
2577static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2578{
2579 struct blk_mq_hw_ctx *hctx;
2580 int i;
2581
2582 queue_for_each_hw_ctx(q, hctx, i) {
2583 if (shared)
2584 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2585 else
2586 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2587 }
2588}
2589
2590static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set,
2591 bool shared)
2592{
2593 struct request_queue *q;
2594
2595 lockdep_assert_held(&set->tag_list_lock);
2596
2597 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2598 blk_mq_freeze_queue(q);
2599 queue_set_hctx_shared(q, shared);
2600 blk_mq_unfreeze_queue(q);
2601 }
2602}
2603
2604static void blk_mq_del_queue_tag_set(struct request_queue *q)
2605{
2606 struct blk_mq_tag_set *set = q->tag_set;
2607
2608 mutex_lock(&set->tag_list_lock);
2609 list_del_rcu(&q->tag_set_list);
2610 if (list_is_singular(&set->tag_list)) {
2611 /* just transitioned to unshared */
2612 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2613 /* update existing queue */
2614 blk_mq_update_tag_set_depth(set, false);
2615 }
2616 mutex_unlock(&set->tag_list_lock);
2617 INIT_LIST_HEAD(&q->tag_set_list);
2618}
2619
2620static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2621 struct request_queue *q)
2622{
2623 mutex_lock(&set->tag_list_lock);
2624
2625 /*
2626 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2627 */
2628 if (!list_empty(&set->tag_list) &&
2629 !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2630 set->flags |= BLK_MQ_F_TAG_SHARED;
2631 /* update existing queue */
2632 blk_mq_update_tag_set_depth(set, true);
2633 }
2634 if (set->flags & BLK_MQ_F_TAG_SHARED)
2635 queue_set_hctx_shared(q, true);
2636 list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
2637
2638 mutex_unlock(&set->tag_list_lock);
2639}
2640
2641/* All allocations will be freed in release handler of q->mq_kobj */
2642static int blk_mq_alloc_ctxs(struct request_queue *q)
2643{
2644 struct blk_mq_ctxs *ctxs;
2645 int cpu;
2646
2647 ctxs = kzalloc(sizeof(*ctxs), GFP_KERNEL);
2648 if (!ctxs)
2649 return -ENOMEM;
2650
2651 ctxs->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2652 if (!ctxs->queue_ctx)
2653 goto fail;
2654
2655 for_each_possible_cpu(cpu) {
2656 struct blk_mq_ctx *ctx = per_cpu_ptr(ctxs->queue_ctx, cpu);
2657 ctx->ctxs = ctxs;
2658 }
2659
2660 q->mq_kobj = &ctxs->kobj;
2661 q->queue_ctx = ctxs->queue_ctx;
2662
2663 return 0;
2664 fail:
2665 kfree(ctxs);
2666 return -ENOMEM;
2667}
2668
2669/*
2670 * It is the actual release handler for mq, but we do it from
2671 * request queue's release handler for avoiding use-after-free
2672 * and headache because q->mq_kobj shouldn't have been introduced,
2673 * but we can't group ctx/kctx kobj without it.
2674 */
2675void blk_mq_release(struct request_queue *q)
2676{
2677 struct blk_mq_hw_ctx *hctx, *next;
2678 int i;
2679
2680 queue_for_each_hw_ctx(q, hctx, i)
2681 WARN_ON_ONCE(hctx && list_empty(&hctx->hctx_list));
2682
2683 /* all hctx are in .unused_hctx_list now */
2684 list_for_each_entry_safe(hctx, next, &q->unused_hctx_list, hctx_list) {
2685 list_del_init(&hctx->hctx_list);
2686 kobject_put(&hctx->kobj);
2687 }
2688
2689 kfree(q->queue_hw_ctx);
2690
2691 /*
2692 * release .mq_kobj and sw queue's kobject now because
2693 * both share lifetime with request queue.
2694 */
2695 blk_mq_sysfs_deinit(q);
2696}
2697
2698struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2699{
2700 struct request_queue *uninit_q, *q;
2701
2702 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2703 if (!uninit_q)
2704 return ERR_PTR(-ENOMEM);
2705
2706 /*
2707 * Initialize the queue without an elevator. device_add_disk() will do
2708 * the initialization.
2709 */
2710 q = blk_mq_init_allocated_queue(set, uninit_q, false);
2711 if (IS_ERR(q))
2712 blk_cleanup_queue(uninit_q);
2713
2714 return q;
2715}
2716EXPORT_SYMBOL(blk_mq_init_queue);
2717
2718/*
2719 * Helper for setting up a queue with mq ops, given queue depth, and
2720 * the passed in mq ops flags.
2721 */
2722struct request_queue *blk_mq_init_sq_queue(struct blk_mq_tag_set *set,
2723 const struct blk_mq_ops *ops,
2724 unsigned int queue_depth,
2725 unsigned int set_flags)
2726{
2727 struct request_queue *q;
2728 int ret;
2729
2730 memset(set, 0, sizeof(*set));
2731 set->ops = ops;
2732 set->nr_hw_queues = 1;
2733 set->nr_maps = 1;
2734 set->queue_depth = queue_depth;
2735 set->numa_node = NUMA_NO_NODE;
2736 set->flags = set_flags;
2737
2738 ret = blk_mq_alloc_tag_set(set);
2739 if (ret)
2740 return ERR_PTR(ret);
2741
2742 q = blk_mq_init_queue(set);
2743 if (IS_ERR(q)) {
2744 blk_mq_free_tag_set(set);
2745 return q;
2746 }
2747
2748 return q;
2749}
2750EXPORT_SYMBOL(blk_mq_init_sq_queue);
2751
2752static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
2753 struct blk_mq_tag_set *set, struct request_queue *q,
2754 int hctx_idx, int node)
2755{
2756 struct blk_mq_hw_ctx *hctx = NULL, *tmp;
2757
2758 /* reuse dead hctx first */
2759 spin_lock(&q->unused_hctx_lock);
2760 list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) {
2761 if (tmp->numa_node == node) {
2762 hctx = tmp;
2763 break;
2764 }
2765 }
2766 if (hctx)
2767 list_del_init(&hctx->hctx_list);
2768 spin_unlock(&q->unused_hctx_lock);
2769
2770 if (!hctx)
2771 hctx = blk_mq_alloc_hctx(q, set, node);
2772 if (!hctx)
2773 goto fail;
2774
2775 if (blk_mq_init_hctx(q, set, hctx, hctx_idx))
2776 goto free_hctx;
2777
2778 return hctx;
2779
2780 free_hctx:
2781 kobject_put(&hctx->kobj);
2782 fail:
2783 return NULL;
2784}
2785
2786static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2787 struct request_queue *q)
2788{
2789 int i, j, end;
2790 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2791
2792 /* protect against switching io scheduler */
2793 mutex_lock(&q->sysfs_lock);
2794 for (i = 0; i < set->nr_hw_queues; i++) {
2795 int node;
2796 struct blk_mq_hw_ctx *hctx;
2797
2798 node = blk_mq_hw_queue_to_node(&set->map[HCTX_TYPE_DEFAULT], i);
2799 /*
2800 * If the hw queue has been mapped to another numa node,
2801 * we need to realloc the hctx. If allocation fails, fallback
2802 * to use the previous one.
2803 */
2804 if (hctxs[i] && (hctxs[i]->numa_node == node))
2805 continue;
2806
2807 hctx = blk_mq_alloc_and_init_hctx(set, q, i, node);
2808 if (hctx) {
2809 if (hctxs[i])
2810 blk_mq_exit_hctx(q, set, hctxs[i], i);
2811 hctxs[i] = hctx;
2812 } else {
2813 if (hctxs[i])
2814 pr_warn("Allocate new hctx on node %d fails,\
2815 fallback to previous one on node %d\n",
2816 node, hctxs[i]->numa_node);
2817 else
2818 break;
2819 }
2820 }
2821 /*
2822 * Increasing nr_hw_queues fails. Free the newly allocated
2823 * hctxs and keep the previous q->nr_hw_queues.
2824 */
2825 if (i != set->nr_hw_queues) {
2826 j = q->nr_hw_queues;
2827 end = i;
2828 } else {
2829 j = i;
2830 end = q->nr_hw_queues;
2831 q->nr_hw_queues = set->nr_hw_queues;
2832 }
2833
2834 for (; j < end; j++) {
2835 struct blk_mq_hw_ctx *hctx = hctxs[j];
2836
2837 if (hctx) {
2838 if (hctx->tags)
2839 blk_mq_free_map_and_requests(set, j);
2840 blk_mq_exit_hctx(q, set, hctx, j);
2841 hctxs[j] = NULL;
2842 }
2843 }
2844 mutex_unlock(&q->sysfs_lock);
2845}
2846
2847/*
2848 * Maximum number of hardware queues we support. For single sets, we'll never
2849 * have more than the CPUs (software queues). For multiple sets, the tag_set
2850 * user may have set ->nr_hw_queues larger.
2851 */
2852static unsigned int nr_hw_queues(struct blk_mq_tag_set *set)
2853{
2854 if (set->nr_maps == 1)
2855 return nr_cpu_ids;
2856
2857 return max(set->nr_hw_queues, nr_cpu_ids);
2858}
2859
2860struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2861 struct request_queue *q,
2862 bool elevator_init)
2863{
2864 /* mark the queue as mq asap */
2865 q->mq_ops = set->ops;
2866
2867 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2868 blk_mq_poll_stats_bkt,
2869 BLK_MQ_POLL_STATS_BKTS, q);
2870 if (!q->poll_cb)
2871 goto err_exit;
2872
2873 if (blk_mq_alloc_ctxs(q))
2874 goto err_poll;
2875
2876 /* init q->mq_kobj and sw queues' kobjects */
2877 blk_mq_sysfs_init(q);
2878
2879 q->nr_queues = nr_hw_queues(set);
2880 q->queue_hw_ctx = kcalloc_node(q->nr_queues, sizeof(*(q->queue_hw_ctx)),
2881 GFP_KERNEL, set->numa_node);
2882 if (!q->queue_hw_ctx)
2883 goto err_sys_init;
2884
2885 INIT_LIST_HEAD(&q->unused_hctx_list);
2886 spin_lock_init(&q->unused_hctx_lock);
2887
2888 blk_mq_realloc_hw_ctxs(set, q);
2889 if (!q->nr_hw_queues)
2890 goto err_hctxs;
2891
2892 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2893 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2894
2895 q->tag_set = set;
2896
2897 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2898 if (set->nr_maps > HCTX_TYPE_POLL &&
2899 set->map[HCTX_TYPE_POLL].nr_queues)
2900 blk_queue_flag_set(QUEUE_FLAG_POLL, q);
2901
2902 q->sg_reserved_size = INT_MAX;
2903
2904 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2905 INIT_LIST_HEAD(&q->requeue_list);
2906 spin_lock_init(&q->requeue_lock);
2907
2908 blk_queue_make_request(q, blk_mq_make_request);
2909
2910 /*
2911 * Do this after blk_queue_make_request() overrides it...
2912 */
2913 q->nr_requests = set->queue_depth;
2914
2915 /*
2916 * Default to classic polling
2917 */
2918 q->poll_nsec = BLK_MQ_POLL_CLASSIC;
2919
2920 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2921 blk_mq_add_queue_tag_set(set, q);
2922 blk_mq_map_swqueue(q);
2923
2924 if (elevator_init)
2925 elevator_init_mq(q);
2926
2927 return q;
2928
2929err_hctxs:
2930 kfree(q->queue_hw_ctx);
2931 q->nr_hw_queues = 0;
2932err_sys_init:
2933 blk_mq_sysfs_deinit(q);
2934err_poll:
2935 blk_stat_free_callback(q->poll_cb);
2936 q->poll_cb = NULL;
2937err_exit:
2938 q->mq_ops = NULL;
2939 return ERR_PTR(-ENOMEM);
2940}
2941EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2942
2943/* tags can _not_ be used after returning from blk_mq_exit_queue */
2944void blk_mq_exit_queue(struct request_queue *q)
2945{
2946 struct blk_mq_tag_set *set = q->tag_set;
2947
2948 blk_mq_del_queue_tag_set(q);
2949 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2950}
2951
2952static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2953{
2954 int i;
2955
2956 for (i = 0; i < set->nr_hw_queues; i++)
2957 if (!__blk_mq_alloc_rq_map(set, i))
2958 goto out_unwind;
2959
2960 return 0;
2961
2962out_unwind:
2963 while (--i >= 0)
2964 blk_mq_free_rq_map(set->tags[i]);
2965
2966 return -ENOMEM;
2967}
2968
2969/*
2970 * Allocate the request maps associated with this tag_set. Note that this
2971 * may reduce the depth asked for, if memory is tight. set->queue_depth
2972 * will be updated to reflect the allocated depth.
2973 */
2974static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2975{
2976 unsigned int depth;
2977 int err;
2978
2979 depth = set->queue_depth;
2980 do {
2981 err = __blk_mq_alloc_rq_maps(set);
2982 if (!err)
2983 break;
2984
2985 set->queue_depth >>= 1;
2986 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2987 err = -ENOMEM;
2988 break;
2989 }
2990 } while (set->queue_depth);
2991
2992 if (!set->queue_depth || err) {
2993 pr_err("blk-mq: failed to allocate request map\n");
2994 return -ENOMEM;
2995 }
2996
2997 if (depth != set->queue_depth)
2998 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2999 depth, set->queue_depth);
3000
3001 return 0;
3002}
3003
3004static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
3005{
3006 if (set->ops->map_queues && !is_kdump_kernel()) {
3007 int i;
3008
3009 /*
3010 * transport .map_queues is usually done in the following
3011 * way:
3012 *
3013 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3014 * mask = get_cpu_mask(queue)
3015 * for_each_cpu(cpu, mask)
3016 * set->map[x].mq_map[cpu] = queue;
3017 * }
3018 *
3019 * When we need to remap, the table has to be cleared for
3020 * killing stale mapping since one CPU may not be mapped
3021 * to any hw queue.
3022 */
3023 for (i = 0; i < set->nr_maps; i++)
3024 blk_mq_clear_mq_map(&set->map[i]);
3025
3026 return set->ops->map_queues(set);
3027 } else {
3028 BUG_ON(set->nr_maps > 1);
3029 return blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3030 }
3031}
3032
3033/*
3034 * Alloc a tag set to be associated with one or more request queues.
3035 * May fail with EINVAL for various error conditions. May adjust the
3036 * requested depth down, if it's too large. In that case, the set
3037 * value will be stored in set->queue_depth.
3038 */
3039int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
3040{
3041 int i, ret;
3042
3043 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
3044
3045 if (!set->nr_hw_queues)
3046 return -EINVAL;
3047 if (!set->queue_depth)
3048 return -EINVAL;
3049 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
3050 return -EINVAL;
3051
3052 if (!set->ops->queue_rq)
3053 return -EINVAL;
3054
3055 if (!set->ops->get_budget ^ !set->ops->put_budget)
3056 return -EINVAL;
3057
3058 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
3059 pr_info("blk-mq: reduced tag depth to %u\n",
3060 BLK_MQ_MAX_DEPTH);
3061 set->queue_depth = BLK_MQ_MAX_DEPTH;
3062 }
3063
3064 if (!set->nr_maps)
3065 set->nr_maps = 1;
3066 else if (set->nr_maps > HCTX_MAX_TYPES)
3067 return -EINVAL;
3068
3069 /*
3070 * If a crashdump is active, then we are potentially in a very
3071 * memory constrained environment. Limit us to 1 queue and
3072 * 64 tags to prevent using too much memory.
3073 */
3074 if (is_kdump_kernel()) {
3075 set->nr_hw_queues = 1;
3076 set->nr_maps = 1;
3077 set->queue_depth = min(64U, set->queue_depth);
3078 }
3079 /*
3080 * There is no use for more h/w queues than cpus if we just have
3081 * a single map
3082 */
3083 if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids)
3084 set->nr_hw_queues = nr_cpu_ids;
3085
3086 set->tags = kcalloc_node(nr_hw_queues(set), sizeof(struct blk_mq_tags *),
3087 GFP_KERNEL, set->numa_node);
3088 if (!set->tags)
3089 return -ENOMEM;
3090
3091 ret = -ENOMEM;
3092 for (i = 0; i < set->nr_maps; i++) {
3093 set->map[i].mq_map = kcalloc_node(nr_cpu_ids,
3094 sizeof(set->map[i].mq_map[0]),
3095 GFP_KERNEL, set->numa_node);
3096 if (!set->map[i].mq_map)
3097 goto out_free_mq_map;
3098 set->map[i].nr_queues = is_kdump_kernel() ? 1 : set->nr_hw_queues;
3099 }
3100
3101 ret = blk_mq_update_queue_map(set);
3102 if (ret)
3103 goto out_free_mq_map;
3104
3105 ret = blk_mq_alloc_rq_maps(set);
3106 if (ret)
3107 goto out_free_mq_map;
3108
3109 mutex_init(&set->tag_list_lock);
3110 INIT_LIST_HEAD(&set->tag_list);
3111
3112 return 0;
3113
3114out_free_mq_map:
3115 for (i = 0; i < set->nr_maps; i++) {
3116 kfree(set->map[i].mq_map);
3117 set->map[i].mq_map = NULL;
3118 }
3119 kfree(set->tags);
3120 set->tags = NULL;
3121 return ret;
3122}
3123EXPORT_SYMBOL(blk_mq_alloc_tag_set);
3124
3125void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
3126{
3127 int i, j;
3128
3129 for (i = 0; i < nr_hw_queues(set); i++)
3130 blk_mq_free_map_and_requests(set, i);
3131
3132 for (j = 0; j < set->nr_maps; j++) {
3133 kfree(set->map[j].mq_map);
3134 set->map[j].mq_map = NULL;
3135 }
3136
3137 kfree(set->tags);
3138 set->tags = NULL;
3139}
3140EXPORT_SYMBOL(blk_mq_free_tag_set);
3141
3142int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
3143{
3144 struct blk_mq_tag_set *set = q->tag_set;
3145 struct blk_mq_hw_ctx *hctx;
3146 int i, ret;
3147
3148 if (!set)
3149 return -EINVAL;
3150
3151 if (q->nr_requests == nr)
3152 return 0;
3153
3154 blk_mq_freeze_queue(q);
3155 blk_mq_quiesce_queue(q);
3156
3157 ret = 0;
3158 queue_for_each_hw_ctx(q, hctx, i) {
3159 if (!hctx->tags)
3160 continue;
3161 /*
3162 * If we're using an MQ scheduler, just update the scheduler
3163 * queue depth. This is similar to what the old code would do.
3164 */
3165 if (!hctx->sched_tags) {
3166 ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
3167 false);
3168 } else {
3169 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
3170 nr, true);
3171 }
3172 if (ret)
3173 break;
3174 if (q->elevator && q->elevator->type->ops.depth_updated)
3175 q->elevator->type->ops.depth_updated(hctx);
3176 }
3177
3178 if (!ret)
3179 q->nr_requests = nr;
3180
3181 blk_mq_unquiesce_queue(q);
3182 blk_mq_unfreeze_queue(q);
3183
3184 return ret;
3185}
3186
3187/*
3188 * request_queue and elevator_type pair.
3189 * It is just used by __blk_mq_update_nr_hw_queues to cache
3190 * the elevator_type associated with a request_queue.
3191 */
3192struct blk_mq_qe_pair {
3193 struct list_head node;
3194 struct request_queue *q;
3195 struct elevator_type *type;
3196};
3197
3198/*
3199 * Cache the elevator_type in qe pair list and switch the
3200 * io scheduler to 'none'
3201 */
3202static bool blk_mq_elv_switch_none(struct list_head *head,
3203 struct request_queue *q)
3204{
3205 struct blk_mq_qe_pair *qe;
3206
3207 if (!q->elevator)
3208 return true;
3209
3210 qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
3211 if (!qe)
3212 return false;
3213
3214 INIT_LIST_HEAD(&qe->node);
3215 qe->q = q;
3216 qe->type = q->elevator->type;
3217 list_add(&qe->node, head);
3218
3219 mutex_lock(&q->sysfs_lock);
3220 /*
3221 * After elevator_switch_mq, the previous elevator_queue will be
3222 * released by elevator_release. The reference of the io scheduler
3223 * module get by elevator_get will also be put. So we need to get
3224 * a reference of the io scheduler module here to prevent it to be
3225 * removed.
3226 */
3227 __module_get(qe->type->elevator_owner);
3228 elevator_switch_mq(q, NULL);
3229 mutex_unlock(&q->sysfs_lock);
3230
3231 return true;
3232}
3233
3234static void blk_mq_elv_switch_back(struct list_head *head,
3235 struct request_queue *q)
3236{
3237 struct blk_mq_qe_pair *qe;
3238 struct elevator_type *t = NULL;
3239
3240 list_for_each_entry(qe, head, node)
3241 if (qe->q == q) {
3242 t = qe->type;
3243 break;
3244 }
3245
3246 if (!t)
3247 return;
3248
3249 list_del(&qe->node);
3250 kfree(qe);
3251
3252 mutex_lock(&q->sysfs_lock);
3253 elevator_switch_mq(q, t);
3254 mutex_unlock(&q->sysfs_lock);
3255}
3256
3257static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
3258 int nr_hw_queues)
3259{
3260 struct request_queue *q;
3261 LIST_HEAD(head);
3262 int prev_nr_hw_queues;
3263
3264 lockdep_assert_held(&set->tag_list_lock);
3265
3266 if (set->nr_maps == 1 && nr_hw_queues > nr_cpu_ids)
3267 nr_hw_queues = nr_cpu_ids;
3268 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
3269 return;
3270
3271 list_for_each_entry(q, &set->tag_list, tag_set_list)
3272 blk_mq_freeze_queue(q);
3273 /*
3274 * Sync with blk_mq_queue_tag_busy_iter.
3275 */
3276 synchronize_rcu();
3277 /*
3278 * Switch IO scheduler to 'none', cleaning up the data associated
3279 * with the previous scheduler. We will switch back once we are done
3280 * updating the new sw to hw queue mappings.
3281 */
3282 list_for_each_entry(q, &set->tag_list, tag_set_list)
3283 if (!blk_mq_elv_switch_none(&head, q))
3284 goto switch_back;
3285
3286 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3287 blk_mq_debugfs_unregister_hctxs(q);
3288 blk_mq_sysfs_unregister(q);
3289 }
3290
3291 prev_nr_hw_queues = set->nr_hw_queues;
3292 set->nr_hw_queues = nr_hw_queues;
3293 blk_mq_update_queue_map(set);
3294fallback:
3295 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3296 blk_mq_realloc_hw_ctxs(set, q);
3297 if (q->nr_hw_queues != set->nr_hw_queues) {
3298 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3299 nr_hw_queues, prev_nr_hw_queues);
3300 set->nr_hw_queues = prev_nr_hw_queues;
3301 blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
3302 goto fallback;
3303 }
3304 blk_mq_map_swqueue(q);
3305 }
3306
3307 list_for_each_entry(q, &set->tag_list, tag_set_list) {
3308 blk_mq_sysfs_register(q);
3309 blk_mq_debugfs_register_hctxs(q);
3310 }
3311
3312switch_back:
3313 list_for_each_entry(q, &set->tag_list, tag_set_list)
3314 blk_mq_elv_switch_back(&head, q);
3315
3316 list_for_each_entry(q, &set->tag_list, tag_set_list)
3317 blk_mq_unfreeze_queue(q);
3318}
3319
3320void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
3321{
3322 mutex_lock(&set->tag_list_lock);
3323 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
3324 mutex_unlock(&set->tag_list_lock);
3325}
3326EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
3327
3328/* Enable polling stats and return whether they were already enabled. */
3329static bool blk_poll_stats_enable(struct request_queue *q)
3330{
3331 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3332 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
3333 return true;
3334 blk_stat_add_callback(q, q->poll_cb);
3335 return false;
3336}
3337
3338static void blk_mq_poll_stats_start(struct request_queue *q)
3339{
3340 /*
3341 * We don't arm the callback if polling stats are not enabled or the
3342 * callback is already active.
3343 */
3344 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3345 blk_stat_is_active(q->poll_cb))
3346 return;
3347
3348 blk_stat_activate_msecs(q->poll_cb, 100);
3349}
3350
3351static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
3352{
3353 struct request_queue *q = cb->data;
3354 int bucket;
3355
3356 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
3357 if (cb->stat[bucket].nr_samples)
3358 q->poll_stat[bucket] = cb->stat[bucket];
3359 }
3360}
3361
3362static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
3363 struct blk_mq_hw_ctx *hctx,
3364 struct request *rq)
3365{
3366 unsigned long ret = 0;
3367 int bucket;
3368
3369 /*
3370 * If stats collection isn't on, don't sleep but turn it on for
3371 * future users
3372 */
3373 if (!blk_poll_stats_enable(q))
3374 return 0;
3375
3376 /*
3377 * As an optimistic guess, use half of the mean service time
3378 * for this type of request. We can (and should) make this smarter.
3379 * For instance, if the completion latencies are tight, we can
3380 * get closer than just half the mean. This is especially
3381 * important on devices where the completion latencies are longer
3382 * than ~10 usec. We do use the stats for the relevant IO size
3383 * if available which does lead to better estimates.
3384 */
3385 bucket = blk_mq_poll_stats_bkt(rq);
3386 if (bucket < 0)
3387 return ret;
3388
3389 if (q->poll_stat[bucket].nr_samples)
3390 ret = (q->poll_stat[bucket].mean + 1) / 2;
3391
3392 return ret;
3393}
3394
3395static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
3396 struct blk_mq_hw_ctx *hctx,
3397 struct request *rq)
3398{
3399 struct hrtimer_sleeper hs;
3400 enum hrtimer_mode mode;
3401 unsigned int nsecs;
3402 ktime_t kt;
3403
3404 if (rq->rq_flags & RQF_MQ_POLL_SLEPT)
3405 return false;
3406
3407 /*
3408 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3409 *
3410 * 0: use half of prev avg
3411 * >0: use this specific value
3412 */
3413 if (q->poll_nsec > 0)
3414 nsecs = q->poll_nsec;
3415 else
3416 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
3417
3418 if (!nsecs)
3419 return false;
3420
3421 rq->rq_flags |= RQF_MQ_POLL_SLEPT;
3422
3423 /*
3424 * This will be replaced with the stats tracking code, using
3425 * 'avg_completion_time / 2' as the pre-sleep target.
3426 */
3427 kt = nsecs;
3428
3429 mode = HRTIMER_MODE_REL;
3430 hrtimer_init_sleeper_on_stack(&hs, CLOCK_MONOTONIC, mode);
3431 hrtimer_set_expires(&hs.timer, kt);
3432
3433 do {
3434 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
3435 break;
3436 set_current_state(TASK_UNINTERRUPTIBLE);
3437 hrtimer_sleeper_start_expires(&hs, mode);
3438 if (hs.task)
3439 io_schedule();
3440 hrtimer_cancel(&hs.timer);
3441 mode = HRTIMER_MODE_ABS;
3442 } while (hs.task && !signal_pending(current));
3443
3444 __set_current_state(TASK_RUNNING);
3445 destroy_hrtimer_on_stack(&hs.timer);
3446 return true;
3447}
3448
3449static bool blk_mq_poll_hybrid(struct request_queue *q,
3450 struct blk_mq_hw_ctx *hctx, blk_qc_t cookie)
3451{
3452 struct request *rq;
3453
3454 if (q->poll_nsec == BLK_MQ_POLL_CLASSIC)
3455 return false;
3456
3457 if (!blk_qc_t_is_internal(cookie))
3458 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
3459 else {
3460 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
3461 /*
3462 * With scheduling, if the request has completed, we'll
3463 * get a NULL return here, as we clear the sched tag when
3464 * that happens. The request still remains valid, like always,
3465 * so we should be safe with just the NULL check.
3466 */
3467 if (!rq)
3468 return false;
3469 }
3470
3471 return blk_mq_poll_hybrid_sleep(q, hctx, rq);
3472}
3473
3474/**
3475 * blk_poll - poll for IO completions
3476 * @q: the queue
3477 * @cookie: cookie passed back at IO submission time
3478 * @spin: whether to spin for completions
3479 *
3480 * Description:
3481 * Poll for completions on the passed in queue. Returns number of
3482 * completed entries found. If @spin is true, then blk_poll will continue
3483 * looping until at least one completion is found, unless the task is
3484 * otherwise marked running (or we need to reschedule).
3485 */
3486int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
3487{
3488 struct blk_mq_hw_ctx *hctx;
3489 long state;
3490
3491 if (!blk_qc_t_valid(cookie) ||
3492 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3493 return 0;
3494
3495 if (current->plug)
3496 blk_flush_plug_list(current->plug, false);
3497
3498 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3499
3500 /*
3501 * If we sleep, have the caller restart the poll loop to reset
3502 * the state. Like for the other success return cases, the
3503 * caller is responsible for checking if the IO completed. If
3504 * the IO isn't complete, we'll get called again and will go
3505 * straight to the busy poll loop.
3506 */
3507 if (blk_mq_poll_hybrid(q, hctx, cookie))
3508 return 1;
3509
3510 hctx->poll_considered++;
3511
3512 state = current->state;
3513 do {
3514 int ret;
3515
3516 hctx->poll_invoked++;
3517
3518 ret = q->mq_ops->poll(hctx);
3519 if (ret > 0) {
3520 hctx->poll_success++;
3521 __set_current_state(TASK_RUNNING);
3522 return ret;
3523 }
3524
3525 if (signal_pending_state(state, current))
3526 __set_current_state(TASK_RUNNING);
3527
3528 if (current->state == TASK_RUNNING)
3529 return 1;
3530 if (ret < 0 || !spin)
3531 break;
3532 cpu_relax();
3533 } while (!need_resched());
3534
3535 __set_current_state(TASK_RUNNING);
3536 return 0;
3537}
3538EXPORT_SYMBOL_GPL(blk_poll);
3539
3540unsigned int blk_mq_rq_cpu(struct request *rq)
3541{
3542 return rq->mq_ctx->cpu;
3543}
3544EXPORT_SYMBOL(blk_mq_rq_cpu);
3545
3546static int __init blk_mq_init(void)
3547{
3548 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
3549 blk_mq_hctx_notify_dead);
3550 return 0;
3551}
3552subsys_initcall(blk_mq_init);