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1/*
2 * Block multiqueue core code
3 *
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
6 */
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <linux/backing-dev.h>
10#include <linux/bio.h>
11#include <linux/blkdev.h>
12#include <linux/kmemleak.h>
13#include <linux/mm.h>
14#include <linux/init.h>
15#include <linux/slab.h>
16#include <linux/workqueue.h>
17#include <linux/smp.h>
18#include <linux/llist.h>
19#include <linux/list_sort.h>
20#include <linux/cpu.h>
21#include <linux/cache.h>
22#include <linux/sched/sysctl.h>
23#include <linux/sched/topology.h>
24#include <linux/sched/signal.h>
25#include <linux/delay.h>
26#include <linux/crash_dump.h>
27#include <linux/prefetch.h>
28
29#include <trace/events/block.h>
30
31#include <linux/blk-mq.h>
32#include "blk.h"
33#include "blk-mq.h"
34#include "blk-mq-debugfs.h"
35#include "blk-mq-tag.h"
36#include "blk-stat.h"
37#include "blk-wbt.h"
38#include "blk-mq-sched.h"
39
40static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie);
41static void blk_mq_poll_stats_start(struct request_queue *q);
42static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
43
44static int blk_mq_poll_stats_bkt(const struct request *rq)
45{
46 int ddir, bytes, bucket;
47
48 ddir = rq_data_dir(rq);
49 bytes = blk_rq_bytes(rq);
50
51 bucket = ddir + 2*(ilog2(bytes) - 9);
52
53 if (bucket < 0)
54 return -1;
55 else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
56 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
57
58 return bucket;
59}
60
61/*
62 * Check if any of the ctx's have pending work in this hardware queue
63 */
64static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
65{
66 return !list_empty_careful(&hctx->dispatch) ||
67 sbitmap_any_bit_set(&hctx->ctx_map) ||
68 blk_mq_sched_has_work(hctx);
69}
70
71/*
72 * Mark this ctx as having pending work in this hardware queue
73 */
74static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
75 struct blk_mq_ctx *ctx)
76{
77 if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
78 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
79}
80
81static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
82 struct blk_mq_ctx *ctx)
83{
84 sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
85}
86
87struct mq_inflight {
88 struct hd_struct *part;
89 unsigned int *inflight;
90};
91
92static void blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
93 struct request *rq, void *priv,
94 bool reserved)
95{
96 struct mq_inflight *mi = priv;
97
98 /*
99 * index[0] counts the specific partition that was asked for. index[1]
100 * counts the ones that are active on the whole device, so increment
101 * that if mi->part is indeed a partition, and not a whole device.
102 */
103 if (rq->part == mi->part)
104 mi->inflight[0]++;
105 if (mi->part->partno)
106 mi->inflight[1]++;
107}
108
109void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
110 unsigned int inflight[2])
111{
112 struct mq_inflight mi = { .part = part, .inflight = inflight, };
113
114 inflight[0] = inflight[1] = 0;
115 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
116}
117
118static void blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
119 struct request *rq, void *priv,
120 bool reserved)
121{
122 struct mq_inflight *mi = priv;
123
124 if (rq->part == mi->part)
125 mi->inflight[rq_data_dir(rq)]++;
126}
127
128void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
129 unsigned int inflight[2])
130{
131 struct mq_inflight mi = { .part = part, .inflight = inflight, };
132
133 inflight[0] = inflight[1] = 0;
134 blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi);
135}
136
137void blk_freeze_queue_start(struct request_queue *q)
138{
139 int freeze_depth;
140
141 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
142 if (freeze_depth == 1) {
143 percpu_ref_kill(&q->q_usage_counter);
144 if (q->mq_ops)
145 blk_mq_run_hw_queues(q, false);
146 }
147}
148EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
149
150void blk_mq_freeze_queue_wait(struct request_queue *q)
151{
152 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
153}
154EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
155
156int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
157 unsigned long timeout)
158{
159 return wait_event_timeout(q->mq_freeze_wq,
160 percpu_ref_is_zero(&q->q_usage_counter),
161 timeout);
162}
163EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
164
165/*
166 * Guarantee no request is in use, so we can change any data structure of
167 * the queue afterward.
168 */
169void blk_freeze_queue(struct request_queue *q)
170{
171 /*
172 * In the !blk_mq case we are only calling this to kill the
173 * q_usage_counter, otherwise this increases the freeze depth
174 * and waits for it to return to zero. For this reason there is
175 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
176 * exported to drivers as the only user for unfreeze is blk_mq.
177 */
178 blk_freeze_queue_start(q);
179 if (!q->mq_ops)
180 blk_drain_queue(q);
181 blk_mq_freeze_queue_wait(q);
182}
183
184void blk_mq_freeze_queue(struct request_queue *q)
185{
186 /*
187 * ...just an alias to keep freeze and unfreeze actions balanced
188 * in the blk_mq_* namespace
189 */
190 blk_freeze_queue(q);
191}
192EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
193
194void blk_mq_unfreeze_queue(struct request_queue *q)
195{
196 int freeze_depth;
197
198 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
199 WARN_ON_ONCE(freeze_depth < 0);
200 if (!freeze_depth) {
201 percpu_ref_reinit(&q->q_usage_counter);
202 wake_up_all(&q->mq_freeze_wq);
203 }
204}
205EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
206
207/*
208 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
209 * mpt3sas driver such that this function can be removed.
210 */
211void blk_mq_quiesce_queue_nowait(struct request_queue *q)
212{
213 blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
214}
215EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
216
217/**
218 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
219 * @q: request queue.
220 *
221 * Note: this function does not prevent that the struct request end_io()
222 * callback function is invoked. Once this function is returned, we make
223 * sure no dispatch can happen until the queue is unquiesced via
224 * blk_mq_unquiesce_queue().
225 */
226void blk_mq_quiesce_queue(struct request_queue *q)
227{
228 struct blk_mq_hw_ctx *hctx;
229 unsigned int i;
230 bool rcu = false;
231
232 blk_mq_quiesce_queue_nowait(q);
233
234 queue_for_each_hw_ctx(q, hctx, i) {
235 if (hctx->flags & BLK_MQ_F_BLOCKING)
236 synchronize_srcu(hctx->srcu);
237 else
238 rcu = true;
239 }
240 if (rcu)
241 synchronize_rcu();
242}
243EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
244
245/*
246 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
247 * @q: request queue.
248 *
249 * This function recovers queue into the state before quiescing
250 * which is done by blk_mq_quiesce_queue.
251 */
252void blk_mq_unquiesce_queue(struct request_queue *q)
253{
254 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
255
256 /* dispatch requests which are inserted during quiescing */
257 blk_mq_run_hw_queues(q, true);
258}
259EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
260
261void blk_mq_wake_waiters(struct request_queue *q)
262{
263 struct blk_mq_hw_ctx *hctx;
264 unsigned int i;
265
266 queue_for_each_hw_ctx(q, hctx, i)
267 if (blk_mq_hw_queue_mapped(hctx))
268 blk_mq_tag_wakeup_all(hctx->tags, true);
269}
270
271bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
272{
273 return blk_mq_has_free_tags(hctx->tags);
274}
275EXPORT_SYMBOL(blk_mq_can_queue);
276
277static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
278 unsigned int tag, unsigned int op)
279{
280 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
281 struct request *rq = tags->static_rqs[tag];
282 req_flags_t rq_flags = 0;
283
284 if (data->flags & BLK_MQ_REQ_INTERNAL) {
285 rq->tag = -1;
286 rq->internal_tag = tag;
287 } else {
288 if (blk_mq_tag_busy(data->hctx)) {
289 rq_flags = RQF_MQ_INFLIGHT;
290 atomic_inc(&data->hctx->nr_active);
291 }
292 rq->tag = tag;
293 rq->internal_tag = -1;
294 data->hctx->tags->rqs[rq->tag] = rq;
295 }
296
297 /* csd/requeue_work/fifo_time is initialized before use */
298 rq->q = data->q;
299 rq->mq_ctx = data->ctx;
300 rq->rq_flags = rq_flags;
301 rq->cpu = -1;
302 rq->cmd_flags = op;
303 if (data->flags & BLK_MQ_REQ_PREEMPT)
304 rq->rq_flags |= RQF_PREEMPT;
305 if (blk_queue_io_stat(data->q))
306 rq->rq_flags |= RQF_IO_STAT;
307 INIT_LIST_HEAD(&rq->queuelist);
308 INIT_HLIST_NODE(&rq->hash);
309 RB_CLEAR_NODE(&rq->rb_node);
310 rq->rq_disk = NULL;
311 rq->part = NULL;
312 rq->start_time = jiffies;
313 rq->nr_phys_segments = 0;
314#if defined(CONFIG_BLK_DEV_INTEGRITY)
315 rq->nr_integrity_segments = 0;
316#endif
317 rq->special = NULL;
318 /* tag was already set */
319 rq->extra_len = 0;
320 rq->__deadline = 0;
321
322 INIT_LIST_HEAD(&rq->timeout_list);
323 rq->timeout = 0;
324
325 rq->end_io = NULL;
326 rq->end_io_data = NULL;
327 rq->next_rq = NULL;
328
329#ifdef CONFIG_BLK_CGROUP
330 rq->rl = NULL;
331 set_start_time_ns(rq);
332 rq->io_start_time_ns = 0;
333#endif
334
335 data->ctx->rq_dispatched[op_is_sync(op)]++;
336 return rq;
337}
338
339static struct request *blk_mq_get_request(struct request_queue *q,
340 struct bio *bio, unsigned int op,
341 struct blk_mq_alloc_data *data)
342{
343 struct elevator_queue *e = q->elevator;
344 struct request *rq;
345 unsigned int tag;
346 bool put_ctx_on_error = false;
347
348 blk_queue_enter_live(q);
349 data->q = q;
350 if (likely(!data->ctx)) {
351 data->ctx = blk_mq_get_ctx(q);
352 put_ctx_on_error = true;
353 }
354 if (likely(!data->hctx))
355 data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
356 if (op & REQ_NOWAIT)
357 data->flags |= BLK_MQ_REQ_NOWAIT;
358
359 if (e) {
360 data->flags |= BLK_MQ_REQ_INTERNAL;
361
362 /*
363 * Flush requests are special and go directly to the
364 * dispatch list.
365 */
366 if (!op_is_flush(op) && e->type->ops.mq.limit_depth)
367 e->type->ops.mq.limit_depth(op, data);
368 }
369
370 tag = blk_mq_get_tag(data);
371 if (tag == BLK_MQ_TAG_FAIL) {
372 if (put_ctx_on_error) {
373 blk_mq_put_ctx(data->ctx);
374 data->ctx = NULL;
375 }
376 blk_queue_exit(q);
377 return NULL;
378 }
379
380 rq = blk_mq_rq_ctx_init(data, tag, op);
381 if (!op_is_flush(op)) {
382 rq->elv.icq = NULL;
383 if (e && e->type->ops.mq.prepare_request) {
384 if (e->type->icq_cache && rq_ioc(bio))
385 blk_mq_sched_assign_ioc(rq, bio);
386
387 e->type->ops.mq.prepare_request(rq, bio);
388 rq->rq_flags |= RQF_ELVPRIV;
389 }
390 }
391 data->hctx->queued++;
392 return rq;
393}
394
395struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
396 blk_mq_req_flags_t flags)
397{
398 struct blk_mq_alloc_data alloc_data = { .flags = flags };
399 struct request *rq;
400 int ret;
401
402 ret = blk_queue_enter(q, flags);
403 if (ret)
404 return ERR_PTR(ret);
405
406 rq = blk_mq_get_request(q, NULL, op, &alloc_data);
407 blk_queue_exit(q);
408
409 if (!rq)
410 return ERR_PTR(-EWOULDBLOCK);
411
412 blk_mq_put_ctx(alloc_data.ctx);
413
414 rq->__data_len = 0;
415 rq->__sector = (sector_t) -1;
416 rq->bio = rq->biotail = NULL;
417 return rq;
418}
419EXPORT_SYMBOL(blk_mq_alloc_request);
420
421struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
422 unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
423{
424 struct blk_mq_alloc_data alloc_data = { .flags = flags };
425 struct request *rq;
426 unsigned int cpu;
427 int ret;
428
429 /*
430 * If the tag allocator sleeps we could get an allocation for a
431 * different hardware context. No need to complicate the low level
432 * allocator for this for the rare use case of a command tied to
433 * a specific queue.
434 */
435 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
436 return ERR_PTR(-EINVAL);
437
438 if (hctx_idx >= q->nr_hw_queues)
439 return ERR_PTR(-EIO);
440
441 ret = blk_queue_enter(q, flags);
442 if (ret)
443 return ERR_PTR(ret);
444
445 /*
446 * Check if the hardware context is actually mapped to anything.
447 * If not tell the caller that it should skip this queue.
448 */
449 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
450 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
451 blk_queue_exit(q);
452 return ERR_PTR(-EXDEV);
453 }
454 cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask);
455 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
456
457 rq = blk_mq_get_request(q, NULL, op, &alloc_data);
458 blk_queue_exit(q);
459
460 if (!rq)
461 return ERR_PTR(-EWOULDBLOCK);
462
463 return rq;
464}
465EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
466
467void blk_mq_free_request(struct request *rq)
468{
469 struct request_queue *q = rq->q;
470 struct elevator_queue *e = q->elevator;
471 struct blk_mq_ctx *ctx = rq->mq_ctx;
472 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
473 const int sched_tag = rq->internal_tag;
474
475 if (rq->rq_flags & RQF_ELVPRIV) {
476 if (e && e->type->ops.mq.finish_request)
477 e->type->ops.mq.finish_request(rq);
478 if (rq->elv.icq) {
479 put_io_context(rq->elv.icq->ioc);
480 rq->elv.icq = NULL;
481 }
482 }
483
484 ctx->rq_completed[rq_is_sync(rq)]++;
485 if (rq->rq_flags & RQF_MQ_INFLIGHT)
486 atomic_dec(&hctx->nr_active);
487
488 if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
489 laptop_io_completion(q->backing_dev_info);
490
491 wbt_done(q->rq_wb, &rq->issue_stat);
492
493 if (blk_rq_rl(rq))
494 blk_put_rl(blk_rq_rl(rq));
495
496 blk_mq_rq_update_state(rq, MQ_RQ_IDLE);
497 if (rq->tag != -1)
498 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
499 if (sched_tag != -1)
500 blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
501 blk_mq_sched_restart(hctx);
502 blk_queue_exit(q);
503}
504EXPORT_SYMBOL_GPL(blk_mq_free_request);
505
506inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
507{
508 blk_account_io_done(rq);
509
510 if (rq->end_io) {
511 wbt_done(rq->q->rq_wb, &rq->issue_stat);
512 rq->end_io(rq, error);
513 } else {
514 if (unlikely(blk_bidi_rq(rq)))
515 blk_mq_free_request(rq->next_rq);
516 blk_mq_free_request(rq);
517 }
518}
519EXPORT_SYMBOL(__blk_mq_end_request);
520
521void blk_mq_end_request(struct request *rq, blk_status_t error)
522{
523 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
524 BUG();
525 __blk_mq_end_request(rq, error);
526}
527EXPORT_SYMBOL(blk_mq_end_request);
528
529static void __blk_mq_complete_request_remote(void *data)
530{
531 struct request *rq = data;
532
533 rq->q->softirq_done_fn(rq);
534}
535
536static void __blk_mq_complete_request(struct request *rq)
537{
538 struct blk_mq_ctx *ctx = rq->mq_ctx;
539 bool shared = false;
540 int cpu;
541
542 WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT);
543 blk_mq_rq_update_state(rq, MQ_RQ_COMPLETE);
544
545 if (rq->internal_tag != -1)
546 blk_mq_sched_completed_request(rq);
547 if (rq->rq_flags & RQF_STATS) {
548 blk_mq_poll_stats_start(rq->q);
549 blk_stat_add(rq);
550 }
551
552 if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
553 rq->q->softirq_done_fn(rq);
554 return;
555 }
556
557 cpu = get_cpu();
558 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
559 shared = cpus_share_cache(cpu, ctx->cpu);
560
561 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
562 rq->csd.func = __blk_mq_complete_request_remote;
563 rq->csd.info = rq;
564 rq->csd.flags = 0;
565 smp_call_function_single_async(ctx->cpu, &rq->csd);
566 } else {
567 rq->q->softirq_done_fn(rq);
568 }
569 put_cpu();
570}
571
572static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
573 __releases(hctx->srcu)
574{
575 if (!(hctx->flags & BLK_MQ_F_BLOCKING))
576 rcu_read_unlock();
577 else
578 srcu_read_unlock(hctx->srcu, srcu_idx);
579}
580
581static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
582 __acquires(hctx->srcu)
583{
584 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
585 /* shut up gcc false positive */
586 *srcu_idx = 0;
587 rcu_read_lock();
588 } else
589 *srcu_idx = srcu_read_lock(hctx->srcu);
590}
591
592static void blk_mq_rq_update_aborted_gstate(struct request *rq, u64 gstate)
593{
594 unsigned long flags;
595
596 /*
597 * blk_mq_rq_aborted_gstate() is used from the completion path and
598 * can thus be called from irq context. u64_stats_fetch in the
599 * middle of update on the same CPU leads to lockup. Disable irq
600 * while updating.
601 */
602 local_irq_save(flags);
603 u64_stats_update_begin(&rq->aborted_gstate_sync);
604 rq->aborted_gstate = gstate;
605 u64_stats_update_end(&rq->aborted_gstate_sync);
606 local_irq_restore(flags);
607}
608
609static u64 blk_mq_rq_aborted_gstate(struct request *rq)
610{
611 unsigned int start;
612 u64 aborted_gstate;
613
614 do {
615 start = u64_stats_fetch_begin(&rq->aborted_gstate_sync);
616 aborted_gstate = rq->aborted_gstate;
617 } while (u64_stats_fetch_retry(&rq->aborted_gstate_sync, start));
618
619 return aborted_gstate;
620}
621
622/**
623 * blk_mq_complete_request - end I/O on a request
624 * @rq: the request being processed
625 *
626 * Description:
627 * Ends all I/O on a request. It does not handle partial completions.
628 * The actual completion happens out-of-order, through a IPI handler.
629 **/
630void blk_mq_complete_request(struct request *rq)
631{
632 struct request_queue *q = rq->q;
633 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
634 int srcu_idx;
635
636 if (unlikely(blk_should_fake_timeout(q)))
637 return;
638
639 /*
640 * If @rq->aborted_gstate equals the current instance, timeout is
641 * claiming @rq and we lost. This is synchronized through
642 * hctx_lock(). See blk_mq_timeout_work() for details.
643 *
644 * Completion path never blocks and we can directly use RCU here
645 * instead of hctx_lock() which can be either RCU or SRCU.
646 * However, that would complicate paths which want to synchronize
647 * against us. Let stay in sync with the issue path so that
648 * hctx_lock() covers both issue and completion paths.
649 */
650 hctx_lock(hctx, &srcu_idx);
651 if (blk_mq_rq_aborted_gstate(rq) != rq->gstate)
652 __blk_mq_complete_request(rq);
653 hctx_unlock(hctx, srcu_idx);
654}
655EXPORT_SYMBOL(blk_mq_complete_request);
656
657int blk_mq_request_started(struct request *rq)
658{
659 return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
660}
661EXPORT_SYMBOL_GPL(blk_mq_request_started);
662
663void blk_mq_start_request(struct request *rq)
664{
665 struct request_queue *q = rq->q;
666
667 blk_mq_sched_started_request(rq);
668
669 trace_block_rq_issue(q, rq);
670
671 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
672 blk_stat_set_issue(&rq->issue_stat, blk_rq_sectors(rq));
673 rq->rq_flags |= RQF_STATS;
674 wbt_issue(q->rq_wb, &rq->issue_stat);
675 }
676
677 WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
678
679 /*
680 * Mark @rq in-flight which also advances the generation number,
681 * and register for timeout. Protect with a seqcount to allow the
682 * timeout path to read both @rq->gstate and @rq->deadline
683 * coherently.
684 *
685 * This is the only place where a request is marked in-flight. If
686 * the timeout path reads an in-flight @rq->gstate, the
687 * @rq->deadline it reads together under @rq->gstate_seq is
688 * guaranteed to be the matching one.
689 */
690 preempt_disable();
691 write_seqcount_begin(&rq->gstate_seq);
692
693 blk_mq_rq_update_state(rq, MQ_RQ_IN_FLIGHT);
694 blk_add_timer(rq);
695
696 write_seqcount_end(&rq->gstate_seq);
697 preempt_enable();
698
699 if (q->dma_drain_size && blk_rq_bytes(rq)) {
700 /*
701 * Make sure space for the drain appears. We know we can do
702 * this because max_hw_segments has been adjusted to be one
703 * fewer than the device can handle.
704 */
705 rq->nr_phys_segments++;
706 }
707}
708EXPORT_SYMBOL(blk_mq_start_request);
709
710/*
711 * When we reach here because queue is busy, it's safe to change the state
712 * to IDLE without checking @rq->aborted_gstate because we should still be
713 * holding the RCU read lock and thus protected against timeout.
714 */
715static void __blk_mq_requeue_request(struct request *rq)
716{
717 struct request_queue *q = rq->q;
718
719 blk_mq_put_driver_tag(rq);
720
721 trace_block_rq_requeue(q, rq);
722 wbt_requeue(q->rq_wb, &rq->issue_stat);
723
724 if (blk_mq_rq_state(rq) != MQ_RQ_IDLE) {
725 blk_mq_rq_update_state(rq, MQ_RQ_IDLE);
726 if (q->dma_drain_size && blk_rq_bytes(rq))
727 rq->nr_phys_segments--;
728 }
729}
730
731void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
732{
733 __blk_mq_requeue_request(rq);
734
735 /* this request will be re-inserted to io scheduler queue */
736 blk_mq_sched_requeue_request(rq);
737
738 BUG_ON(blk_queued_rq(rq));
739 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
740}
741EXPORT_SYMBOL(blk_mq_requeue_request);
742
743static void blk_mq_requeue_work(struct work_struct *work)
744{
745 struct request_queue *q =
746 container_of(work, struct request_queue, requeue_work.work);
747 LIST_HEAD(rq_list);
748 struct request *rq, *next;
749
750 spin_lock_irq(&q->requeue_lock);
751 list_splice_init(&q->requeue_list, &rq_list);
752 spin_unlock_irq(&q->requeue_lock);
753
754 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
755 if (!(rq->rq_flags & RQF_SOFTBARRIER))
756 continue;
757
758 rq->rq_flags &= ~RQF_SOFTBARRIER;
759 list_del_init(&rq->queuelist);
760 blk_mq_sched_insert_request(rq, true, false, false);
761 }
762
763 while (!list_empty(&rq_list)) {
764 rq = list_entry(rq_list.next, struct request, queuelist);
765 list_del_init(&rq->queuelist);
766 blk_mq_sched_insert_request(rq, false, false, false);
767 }
768
769 blk_mq_run_hw_queues(q, false);
770}
771
772void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
773 bool kick_requeue_list)
774{
775 struct request_queue *q = rq->q;
776 unsigned long flags;
777
778 /*
779 * We abuse this flag that is otherwise used by the I/O scheduler to
780 * request head insertion from the workqueue.
781 */
782 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
783
784 spin_lock_irqsave(&q->requeue_lock, flags);
785 if (at_head) {
786 rq->rq_flags |= RQF_SOFTBARRIER;
787 list_add(&rq->queuelist, &q->requeue_list);
788 } else {
789 list_add_tail(&rq->queuelist, &q->requeue_list);
790 }
791 spin_unlock_irqrestore(&q->requeue_lock, flags);
792
793 if (kick_requeue_list)
794 blk_mq_kick_requeue_list(q);
795}
796EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
797
798void blk_mq_kick_requeue_list(struct request_queue *q)
799{
800 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0);
801}
802EXPORT_SYMBOL(blk_mq_kick_requeue_list);
803
804void blk_mq_delay_kick_requeue_list(struct request_queue *q,
805 unsigned long msecs)
806{
807 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
808 msecs_to_jiffies(msecs));
809}
810EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
811
812struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
813{
814 if (tag < tags->nr_tags) {
815 prefetch(tags->rqs[tag]);
816 return tags->rqs[tag];
817 }
818
819 return NULL;
820}
821EXPORT_SYMBOL(blk_mq_tag_to_rq);
822
823struct blk_mq_timeout_data {
824 unsigned long next;
825 unsigned int next_set;
826 unsigned int nr_expired;
827};
828
829static void blk_mq_rq_timed_out(struct request *req, bool reserved)
830{
831 const struct blk_mq_ops *ops = req->q->mq_ops;
832 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
833
834 req->rq_flags |= RQF_MQ_TIMEOUT_EXPIRED;
835
836 if (ops->timeout)
837 ret = ops->timeout(req, reserved);
838
839 switch (ret) {
840 case BLK_EH_HANDLED:
841 __blk_mq_complete_request(req);
842 break;
843 case BLK_EH_RESET_TIMER:
844 /*
845 * As nothing prevents from completion happening while
846 * ->aborted_gstate is set, this may lead to ignored
847 * completions and further spurious timeouts.
848 */
849 blk_mq_rq_update_aborted_gstate(req, 0);
850 blk_add_timer(req);
851 break;
852 case BLK_EH_NOT_HANDLED:
853 break;
854 default:
855 printk(KERN_ERR "block: bad eh return: %d\n", ret);
856 break;
857 }
858}
859
860static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
861 struct request *rq, void *priv, bool reserved)
862{
863 struct blk_mq_timeout_data *data = priv;
864 unsigned long gstate, deadline;
865 int start;
866
867 might_sleep();
868
869 if (rq->rq_flags & RQF_MQ_TIMEOUT_EXPIRED)
870 return;
871
872 /* read coherent snapshots of @rq->state_gen and @rq->deadline */
873 while (true) {
874 start = read_seqcount_begin(&rq->gstate_seq);
875 gstate = READ_ONCE(rq->gstate);
876 deadline = blk_rq_deadline(rq);
877 if (!read_seqcount_retry(&rq->gstate_seq, start))
878 break;
879 cond_resched();
880 }
881
882 /* if in-flight && overdue, mark for abortion */
883 if ((gstate & MQ_RQ_STATE_MASK) == MQ_RQ_IN_FLIGHT &&
884 time_after_eq(jiffies, deadline)) {
885 blk_mq_rq_update_aborted_gstate(rq, gstate);
886 data->nr_expired++;
887 hctx->nr_expired++;
888 } else if (!data->next_set || time_after(data->next, deadline)) {
889 data->next = deadline;
890 data->next_set = 1;
891 }
892}
893
894static void blk_mq_terminate_expired(struct blk_mq_hw_ctx *hctx,
895 struct request *rq, void *priv, bool reserved)
896{
897 /*
898 * We marked @rq->aborted_gstate and waited for RCU. If there were
899 * completions that we lost to, they would have finished and
900 * updated @rq->gstate by now; otherwise, the completion path is
901 * now guaranteed to see @rq->aborted_gstate and yield. If
902 * @rq->aborted_gstate still matches @rq->gstate, @rq is ours.
903 */
904 if (!(rq->rq_flags & RQF_MQ_TIMEOUT_EXPIRED) &&
905 READ_ONCE(rq->gstate) == rq->aborted_gstate)
906 blk_mq_rq_timed_out(rq, reserved);
907}
908
909static void blk_mq_timeout_work(struct work_struct *work)
910{
911 struct request_queue *q =
912 container_of(work, struct request_queue, timeout_work);
913 struct blk_mq_timeout_data data = {
914 .next = 0,
915 .next_set = 0,
916 .nr_expired = 0,
917 };
918 struct blk_mq_hw_ctx *hctx;
919 int i;
920
921 /* A deadlock might occur if a request is stuck requiring a
922 * timeout at the same time a queue freeze is waiting
923 * completion, since the timeout code would not be able to
924 * acquire the queue reference here.
925 *
926 * That's why we don't use blk_queue_enter here; instead, we use
927 * percpu_ref_tryget directly, because we need to be able to
928 * obtain a reference even in the short window between the queue
929 * starting to freeze, by dropping the first reference in
930 * blk_freeze_queue_start, and the moment the last request is
931 * consumed, marked by the instant q_usage_counter reaches
932 * zero.
933 */
934 if (!percpu_ref_tryget(&q->q_usage_counter))
935 return;
936
937 /* scan for the expired ones and set their ->aborted_gstate */
938 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
939
940 if (data.nr_expired) {
941 bool has_rcu = false;
942
943 /*
944 * Wait till everyone sees ->aborted_gstate. The
945 * sequential waits for SRCUs aren't ideal. If this ever
946 * becomes a problem, we can add per-hw_ctx rcu_head and
947 * wait in parallel.
948 */
949 queue_for_each_hw_ctx(q, hctx, i) {
950 if (!hctx->nr_expired)
951 continue;
952
953 if (!(hctx->flags & BLK_MQ_F_BLOCKING))
954 has_rcu = true;
955 else
956 synchronize_srcu(hctx->srcu);
957
958 hctx->nr_expired = 0;
959 }
960 if (has_rcu)
961 synchronize_rcu();
962
963 /* terminate the ones we won */
964 blk_mq_queue_tag_busy_iter(q, blk_mq_terminate_expired, NULL);
965 }
966
967 if (data.next_set) {
968 data.next = blk_rq_timeout(round_jiffies_up(data.next));
969 mod_timer(&q->timeout, data.next);
970 } else {
971 /*
972 * Request timeouts are handled as a forward rolling timer. If
973 * we end up here it means that no requests are pending and
974 * also that no request has been pending for a while. Mark
975 * each hctx as idle.
976 */
977 queue_for_each_hw_ctx(q, hctx, i) {
978 /* the hctx may be unmapped, so check it here */
979 if (blk_mq_hw_queue_mapped(hctx))
980 blk_mq_tag_idle(hctx);
981 }
982 }
983 blk_queue_exit(q);
984}
985
986struct flush_busy_ctx_data {
987 struct blk_mq_hw_ctx *hctx;
988 struct list_head *list;
989};
990
991static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
992{
993 struct flush_busy_ctx_data *flush_data = data;
994 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
995 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
996
997 spin_lock(&ctx->lock);
998 list_splice_tail_init(&ctx->rq_list, flush_data->list);
999 sbitmap_clear_bit(sb, bitnr);
1000 spin_unlock(&ctx->lock);
1001 return true;
1002}
1003
1004/*
1005 * Process software queues that have been marked busy, splicing them
1006 * to the for-dispatch
1007 */
1008void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
1009{
1010 struct flush_busy_ctx_data data = {
1011 .hctx = hctx,
1012 .list = list,
1013 };
1014
1015 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
1016}
1017EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
1018
1019struct dispatch_rq_data {
1020 struct blk_mq_hw_ctx *hctx;
1021 struct request *rq;
1022};
1023
1024static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
1025 void *data)
1026{
1027 struct dispatch_rq_data *dispatch_data = data;
1028 struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
1029 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
1030
1031 spin_lock(&ctx->lock);
1032 if (unlikely(!list_empty(&ctx->rq_list))) {
1033 dispatch_data->rq = list_entry_rq(ctx->rq_list.next);
1034 list_del_init(&dispatch_data->rq->queuelist);
1035 if (list_empty(&ctx->rq_list))
1036 sbitmap_clear_bit(sb, bitnr);
1037 }
1038 spin_unlock(&ctx->lock);
1039
1040 return !dispatch_data->rq;
1041}
1042
1043struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
1044 struct blk_mq_ctx *start)
1045{
1046 unsigned off = start ? start->index_hw : 0;
1047 struct dispatch_rq_data data = {
1048 .hctx = hctx,
1049 .rq = NULL,
1050 };
1051
1052 __sbitmap_for_each_set(&hctx->ctx_map, off,
1053 dispatch_rq_from_ctx, &data);
1054
1055 return data.rq;
1056}
1057
1058static inline unsigned int queued_to_index(unsigned int queued)
1059{
1060 if (!queued)
1061 return 0;
1062
1063 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
1064}
1065
1066bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
1067 bool wait)
1068{
1069 struct blk_mq_alloc_data data = {
1070 .q = rq->q,
1071 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
1072 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
1073 };
1074
1075 might_sleep_if(wait);
1076
1077 if (rq->tag != -1)
1078 goto done;
1079
1080 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
1081 data.flags |= BLK_MQ_REQ_RESERVED;
1082
1083 rq->tag = blk_mq_get_tag(&data);
1084 if (rq->tag >= 0) {
1085 if (blk_mq_tag_busy(data.hctx)) {
1086 rq->rq_flags |= RQF_MQ_INFLIGHT;
1087 atomic_inc(&data.hctx->nr_active);
1088 }
1089 data.hctx->tags->rqs[rq->tag] = rq;
1090 }
1091
1092done:
1093 if (hctx)
1094 *hctx = data.hctx;
1095 return rq->tag != -1;
1096}
1097
1098static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
1099 int flags, void *key)
1100{
1101 struct blk_mq_hw_ctx *hctx;
1102
1103 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
1104
1105 list_del_init(&wait->entry);
1106 blk_mq_run_hw_queue(hctx, true);
1107 return 1;
1108}
1109
1110/*
1111 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1112 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1113 * restart. For both cases, take care to check the condition again after
1114 * marking us as waiting.
1115 */
1116static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
1117 struct request *rq)
1118{
1119 struct blk_mq_hw_ctx *this_hctx = *hctx;
1120 struct sbq_wait_state *ws;
1121 wait_queue_entry_t *wait;
1122 bool ret;
1123
1124 if (!(this_hctx->flags & BLK_MQ_F_TAG_SHARED)) {
1125 if (!test_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state))
1126 set_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state);
1127
1128 /*
1129 * It's possible that a tag was freed in the window between the
1130 * allocation failure and adding the hardware queue to the wait
1131 * queue.
1132 *
1133 * Don't clear RESTART here, someone else could have set it.
1134 * At most this will cost an extra queue run.
1135 */
1136 return blk_mq_get_driver_tag(rq, hctx, false);
1137 }
1138
1139 wait = &this_hctx->dispatch_wait;
1140 if (!list_empty_careful(&wait->entry))
1141 return false;
1142
1143 spin_lock(&this_hctx->lock);
1144 if (!list_empty(&wait->entry)) {
1145 spin_unlock(&this_hctx->lock);
1146 return false;
1147 }
1148
1149 ws = bt_wait_ptr(&this_hctx->tags->bitmap_tags, this_hctx);
1150 add_wait_queue(&ws->wait, wait);
1151
1152 /*
1153 * It's possible that a tag was freed in the window between the
1154 * allocation failure and adding the hardware queue to the wait
1155 * queue.
1156 */
1157 ret = blk_mq_get_driver_tag(rq, hctx, false);
1158 if (!ret) {
1159 spin_unlock(&this_hctx->lock);
1160 return false;
1161 }
1162
1163 /*
1164 * We got a tag, remove ourselves from the wait queue to ensure
1165 * someone else gets the wakeup.
1166 */
1167 spin_lock_irq(&ws->wait.lock);
1168 list_del_init(&wait->entry);
1169 spin_unlock_irq(&ws->wait.lock);
1170 spin_unlock(&this_hctx->lock);
1171
1172 return true;
1173}
1174
1175#define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1176
1177bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
1178 bool got_budget)
1179{
1180 struct blk_mq_hw_ctx *hctx;
1181 struct request *rq, *nxt;
1182 bool no_tag = false;
1183 int errors, queued;
1184 blk_status_t ret = BLK_STS_OK;
1185
1186 if (list_empty(list))
1187 return false;
1188
1189 WARN_ON(!list_is_singular(list) && got_budget);
1190
1191 /*
1192 * Now process all the entries, sending them to the driver.
1193 */
1194 errors = queued = 0;
1195 do {
1196 struct blk_mq_queue_data bd;
1197
1198 rq = list_first_entry(list, struct request, queuelist);
1199
1200 hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
1201 if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
1202 break;
1203
1204 if (!blk_mq_get_driver_tag(rq, NULL, false)) {
1205 /*
1206 * The initial allocation attempt failed, so we need to
1207 * rerun the hardware queue when a tag is freed. The
1208 * waitqueue takes care of that. If the queue is run
1209 * before we add this entry back on the dispatch list,
1210 * we'll re-run it below.
1211 */
1212 if (!blk_mq_mark_tag_wait(&hctx, rq)) {
1213 blk_mq_put_dispatch_budget(hctx);
1214 /*
1215 * For non-shared tags, the RESTART check
1216 * will suffice.
1217 */
1218 if (hctx->flags & BLK_MQ_F_TAG_SHARED)
1219 no_tag = true;
1220 break;
1221 }
1222 }
1223
1224 list_del_init(&rq->queuelist);
1225
1226 bd.rq = rq;
1227
1228 /*
1229 * Flag last if we have no more requests, or if we have more
1230 * but can't assign a driver tag to it.
1231 */
1232 if (list_empty(list))
1233 bd.last = true;
1234 else {
1235 nxt = list_first_entry(list, struct request, queuelist);
1236 bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
1237 }
1238
1239 ret = q->mq_ops->queue_rq(hctx, &bd);
1240 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
1241 /*
1242 * If an I/O scheduler has been configured and we got a
1243 * driver tag for the next request already, free it
1244 * again.
1245 */
1246 if (!list_empty(list)) {
1247 nxt = list_first_entry(list, struct request, queuelist);
1248 blk_mq_put_driver_tag(nxt);
1249 }
1250 list_add(&rq->queuelist, list);
1251 __blk_mq_requeue_request(rq);
1252 break;
1253 }
1254
1255 if (unlikely(ret != BLK_STS_OK)) {
1256 errors++;
1257 blk_mq_end_request(rq, BLK_STS_IOERR);
1258 continue;
1259 }
1260
1261 queued++;
1262 } while (!list_empty(list));
1263
1264 hctx->dispatched[queued_to_index(queued)]++;
1265
1266 /*
1267 * Any items that need requeuing? Stuff them into hctx->dispatch,
1268 * that is where we will continue on next queue run.
1269 */
1270 if (!list_empty(list)) {
1271 bool needs_restart;
1272
1273 spin_lock(&hctx->lock);
1274 list_splice_init(list, &hctx->dispatch);
1275 spin_unlock(&hctx->lock);
1276
1277 /*
1278 * If SCHED_RESTART was set by the caller of this function and
1279 * it is no longer set that means that it was cleared by another
1280 * thread and hence that a queue rerun is needed.
1281 *
1282 * If 'no_tag' is set, that means that we failed getting
1283 * a driver tag with an I/O scheduler attached. If our dispatch
1284 * waitqueue is no longer active, ensure that we run the queue
1285 * AFTER adding our entries back to the list.
1286 *
1287 * If no I/O scheduler has been configured it is possible that
1288 * the hardware queue got stopped and restarted before requests
1289 * were pushed back onto the dispatch list. Rerun the queue to
1290 * avoid starvation. Notes:
1291 * - blk_mq_run_hw_queue() checks whether or not a queue has
1292 * been stopped before rerunning a queue.
1293 * - Some but not all block drivers stop a queue before
1294 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1295 * and dm-rq.
1296 *
1297 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1298 * bit is set, run queue after a delay to avoid IO stalls
1299 * that could otherwise occur if the queue is idle.
1300 */
1301 needs_restart = blk_mq_sched_needs_restart(hctx);
1302 if (!needs_restart ||
1303 (no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
1304 blk_mq_run_hw_queue(hctx, true);
1305 else if (needs_restart && (ret == BLK_STS_RESOURCE))
1306 blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
1307 }
1308
1309 return (queued + errors) != 0;
1310}
1311
1312static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1313{
1314 int srcu_idx;
1315
1316 /*
1317 * We should be running this queue from one of the CPUs that
1318 * are mapped to it.
1319 *
1320 * There are at least two related races now between setting
1321 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1322 * __blk_mq_run_hw_queue():
1323 *
1324 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1325 * but later it becomes online, then this warning is harmless
1326 * at all
1327 *
1328 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1329 * but later it becomes offline, then the warning can't be
1330 * triggered, and we depend on blk-mq timeout handler to
1331 * handle dispatched requests to this hctx
1332 */
1333 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1334 cpu_online(hctx->next_cpu)) {
1335 printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
1336 raw_smp_processor_id(),
1337 cpumask_empty(hctx->cpumask) ? "inactive": "active");
1338 dump_stack();
1339 }
1340
1341 /*
1342 * We can't run the queue inline with ints disabled. Ensure that
1343 * we catch bad users of this early.
1344 */
1345 WARN_ON_ONCE(in_interrupt());
1346
1347 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1348
1349 hctx_lock(hctx, &srcu_idx);
1350 blk_mq_sched_dispatch_requests(hctx);
1351 hctx_unlock(hctx, srcu_idx);
1352}
1353
1354static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
1355{
1356 int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
1357
1358 if (cpu >= nr_cpu_ids)
1359 cpu = cpumask_first(hctx->cpumask);
1360 return cpu;
1361}
1362
1363/*
1364 * It'd be great if the workqueue API had a way to pass
1365 * in a mask and had some smarts for more clever placement.
1366 * For now we just round-robin here, switching for every
1367 * BLK_MQ_CPU_WORK_BATCH queued items.
1368 */
1369static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1370{
1371 bool tried = false;
1372 int next_cpu = hctx->next_cpu;
1373
1374 if (hctx->queue->nr_hw_queues == 1)
1375 return WORK_CPU_UNBOUND;
1376
1377 if (--hctx->next_cpu_batch <= 0) {
1378select_cpu:
1379 next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
1380 cpu_online_mask);
1381 if (next_cpu >= nr_cpu_ids)
1382 next_cpu = blk_mq_first_mapped_cpu(hctx);
1383 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1384 }
1385
1386 /*
1387 * Do unbound schedule if we can't find a online CPU for this hctx,
1388 * and it should only happen in the path of handling CPU DEAD.
1389 */
1390 if (!cpu_online(next_cpu)) {
1391 if (!tried) {
1392 tried = true;
1393 goto select_cpu;
1394 }
1395
1396 /*
1397 * Make sure to re-select CPU next time once after CPUs
1398 * in hctx->cpumask become online again.
1399 */
1400 hctx->next_cpu = next_cpu;
1401 hctx->next_cpu_batch = 1;
1402 return WORK_CPU_UNBOUND;
1403 }
1404
1405 hctx->next_cpu = next_cpu;
1406 return next_cpu;
1407}
1408
1409static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1410 unsigned long msecs)
1411{
1412 if (unlikely(blk_mq_hctx_stopped(hctx)))
1413 return;
1414
1415 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1416 int cpu = get_cpu();
1417 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1418 __blk_mq_run_hw_queue(hctx);
1419 put_cpu();
1420 return;
1421 }
1422
1423 put_cpu();
1424 }
1425
1426 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
1427 msecs_to_jiffies(msecs));
1428}
1429
1430void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1431{
1432 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1433}
1434EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1435
1436bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1437{
1438 int srcu_idx;
1439 bool need_run;
1440
1441 /*
1442 * When queue is quiesced, we may be switching io scheduler, or
1443 * updating nr_hw_queues, or other things, and we can't run queue
1444 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1445 *
1446 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1447 * quiesced.
1448 */
1449 hctx_lock(hctx, &srcu_idx);
1450 need_run = !blk_queue_quiesced(hctx->queue) &&
1451 blk_mq_hctx_has_pending(hctx);
1452 hctx_unlock(hctx, srcu_idx);
1453
1454 if (need_run) {
1455 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1456 return true;
1457 }
1458
1459 return false;
1460}
1461EXPORT_SYMBOL(blk_mq_run_hw_queue);
1462
1463void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1464{
1465 struct blk_mq_hw_ctx *hctx;
1466 int i;
1467
1468 queue_for_each_hw_ctx(q, hctx, i) {
1469 if (blk_mq_hctx_stopped(hctx))
1470 continue;
1471
1472 blk_mq_run_hw_queue(hctx, async);
1473 }
1474}
1475EXPORT_SYMBOL(blk_mq_run_hw_queues);
1476
1477/**
1478 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1479 * @q: request queue.
1480 *
1481 * The caller is responsible for serializing this function against
1482 * blk_mq_{start,stop}_hw_queue().
1483 */
1484bool blk_mq_queue_stopped(struct request_queue *q)
1485{
1486 struct blk_mq_hw_ctx *hctx;
1487 int i;
1488
1489 queue_for_each_hw_ctx(q, hctx, i)
1490 if (blk_mq_hctx_stopped(hctx))
1491 return true;
1492
1493 return false;
1494}
1495EXPORT_SYMBOL(blk_mq_queue_stopped);
1496
1497/*
1498 * This function is often used for pausing .queue_rq() by driver when
1499 * there isn't enough resource or some conditions aren't satisfied, and
1500 * BLK_STS_RESOURCE is usually returned.
1501 *
1502 * We do not guarantee that dispatch can be drained or blocked
1503 * after blk_mq_stop_hw_queue() returns. Please use
1504 * blk_mq_quiesce_queue() for that requirement.
1505 */
1506void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1507{
1508 cancel_delayed_work(&hctx->run_work);
1509
1510 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1511}
1512EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1513
1514/*
1515 * This function is often used for pausing .queue_rq() by driver when
1516 * there isn't enough resource or some conditions aren't satisfied, and
1517 * BLK_STS_RESOURCE is usually returned.
1518 *
1519 * We do not guarantee that dispatch can be drained or blocked
1520 * after blk_mq_stop_hw_queues() returns. Please use
1521 * blk_mq_quiesce_queue() for that requirement.
1522 */
1523void blk_mq_stop_hw_queues(struct request_queue *q)
1524{
1525 struct blk_mq_hw_ctx *hctx;
1526 int i;
1527
1528 queue_for_each_hw_ctx(q, hctx, i)
1529 blk_mq_stop_hw_queue(hctx);
1530}
1531EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1532
1533void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1534{
1535 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1536
1537 blk_mq_run_hw_queue(hctx, false);
1538}
1539EXPORT_SYMBOL(blk_mq_start_hw_queue);
1540
1541void blk_mq_start_hw_queues(struct request_queue *q)
1542{
1543 struct blk_mq_hw_ctx *hctx;
1544 int i;
1545
1546 queue_for_each_hw_ctx(q, hctx, i)
1547 blk_mq_start_hw_queue(hctx);
1548}
1549EXPORT_SYMBOL(blk_mq_start_hw_queues);
1550
1551void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1552{
1553 if (!blk_mq_hctx_stopped(hctx))
1554 return;
1555
1556 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1557 blk_mq_run_hw_queue(hctx, async);
1558}
1559EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1560
1561void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1562{
1563 struct blk_mq_hw_ctx *hctx;
1564 int i;
1565
1566 queue_for_each_hw_ctx(q, hctx, i)
1567 blk_mq_start_stopped_hw_queue(hctx, async);
1568}
1569EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1570
1571static void blk_mq_run_work_fn(struct work_struct *work)
1572{
1573 struct blk_mq_hw_ctx *hctx;
1574
1575 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1576
1577 /*
1578 * If we are stopped, don't run the queue.
1579 */
1580 if (test_bit(BLK_MQ_S_STOPPED, &hctx->state))
1581 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1582
1583 __blk_mq_run_hw_queue(hctx);
1584}
1585
1586static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1587 struct request *rq,
1588 bool at_head)
1589{
1590 struct blk_mq_ctx *ctx = rq->mq_ctx;
1591
1592 lockdep_assert_held(&ctx->lock);
1593
1594 trace_block_rq_insert(hctx->queue, rq);
1595
1596 if (at_head)
1597 list_add(&rq->queuelist, &ctx->rq_list);
1598 else
1599 list_add_tail(&rq->queuelist, &ctx->rq_list);
1600}
1601
1602void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1603 bool at_head)
1604{
1605 struct blk_mq_ctx *ctx = rq->mq_ctx;
1606
1607 lockdep_assert_held(&ctx->lock);
1608
1609 __blk_mq_insert_req_list(hctx, rq, at_head);
1610 blk_mq_hctx_mark_pending(hctx, ctx);
1611}
1612
1613/*
1614 * Should only be used carefully, when the caller knows we want to
1615 * bypass a potential IO scheduler on the target device.
1616 */
1617void blk_mq_request_bypass_insert(struct request *rq, bool run_queue)
1618{
1619 struct blk_mq_ctx *ctx = rq->mq_ctx;
1620 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(rq->q, ctx->cpu);
1621
1622 spin_lock(&hctx->lock);
1623 list_add_tail(&rq->queuelist, &hctx->dispatch);
1624 spin_unlock(&hctx->lock);
1625
1626 if (run_queue)
1627 blk_mq_run_hw_queue(hctx, false);
1628}
1629
1630void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1631 struct list_head *list)
1632
1633{
1634 /*
1635 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1636 * offline now
1637 */
1638 spin_lock(&ctx->lock);
1639 while (!list_empty(list)) {
1640 struct request *rq;
1641
1642 rq = list_first_entry(list, struct request, queuelist);
1643 BUG_ON(rq->mq_ctx != ctx);
1644 list_del_init(&rq->queuelist);
1645 __blk_mq_insert_req_list(hctx, rq, false);
1646 }
1647 blk_mq_hctx_mark_pending(hctx, ctx);
1648 spin_unlock(&ctx->lock);
1649}
1650
1651static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1652{
1653 struct request *rqa = container_of(a, struct request, queuelist);
1654 struct request *rqb = container_of(b, struct request, queuelist);
1655
1656 return !(rqa->mq_ctx < rqb->mq_ctx ||
1657 (rqa->mq_ctx == rqb->mq_ctx &&
1658 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1659}
1660
1661void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1662{
1663 struct blk_mq_ctx *this_ctx;
1664 struct request_queue *this_q;
1665 struct request *rq;
1666 LIST_HEAD(list);
1667 LIST_HEAD(ctx_list);
1668 unsigned int depth;
1669
1670 list_splice_init(&plug->mq_list, &list);
1671
1672 list_sort(NULL, &list, plug_ctx_cmp);
1673
1674 this_q = NULL;
1675 this_ctx = NULL;
1676 depth = 0;
1677
1678 while (!list_empty(&list)) {
1679 rq = list_entry_rq(list.next);
1680 list_del_init(&rq->queuelist);
1681 BUG_ON(!rq->q);
1682 if (rq->mq_ctx != this_ctx) {
1683 if (this_ctx) {
1684 trace_block_unplug(this_q, depth, from_schedule);
1685 blk_mq_sched_insert_requests(this_q, this_ctx,
1686 &ctx_list,
1687 from_schedule);
1688 }
1689
1690 this_ctx = rq->mq_ctx;
1691 this_q = rq->q;
1692 depth = 0;
1693 }
1694
1695 depth++;
1696 list_add_tail(&rq->queuelist, &ctx_list);
1697 }
1698
1699 /*
1700 * If 'this_ctx' is set, we know we have entries to complete
1701 * on 'ctx_list'. Do those.
1702 */
1703 if (this_ctx) {
1704 trace_block_unplug(this_q, depth, from_schedule);
1705 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1706 from_schedule);
1707 }
1708}
1709
1710static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1711{
1712 blk_init_request_from_bio(rq, bio);
1713
1714 blk_rq_set_rl(rq, blk_get_rl(rq->q, bio));
1715
1716 blk_account_io_start(rq, true);
1717}
1718
1719static inline void blk_mq_queue_io(struct blk_mq_hw_ctx *hctx,
1720 struct blk_mq_ctx *ctx,
1721 struct request *rq)
1722{
1723 spin_lock(&ctx->lock);
1724 __blk_mq_insert_request(hctx, rq, false);
1725 spin_unlock(&ctx->lock);
1726}
1727
1728static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1729{
1730 if (rq->tag != -1)
1731 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1732
1733 return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1734}
1735
1736static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
1737 struct request *rq,
1738 blk_qc_t *cookie)
1739{
1740 struct request_queue *q = rq->q;
1741 struct blk_mq_queue_data bd = {
1742 .rq = rq,
1743 .last = true,
1744 };
1745 blk_qc_t new_cookie;
1746 blk_status_t ret;
1747
1748 new_cookie = request_to_qc_t(hctx, rq);
1749
1750 /*
1751 * For OK queue, we are done. For error, caller may kill it.
1752 * Any other error (busy), just add it to our list as we
1753 * previously would have done.
1754 */
1755 ret = q->mq_ops->queue_rq(hctx, &bd);
1756 switch (ret) {
1757 case BLK_STS_OK:
1758 *cookie = new_cookie;
1759 break;
1760 case BLK_STS_RESOURCE:
1761 case BLK_STS_DEV_RESOURCE:
1762 __blk_mq_requeue_request(rq);
1763 break;
1764 default:
1765 *cookie = BLK_QC_T_NONE;
1766 break;
1767 }
1768
1769 return ret;
1770}
1771
1772static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1773 struct request *rq,
1774 blk_qc_t *cookie,
1775 bool bypass_insert)
1776{
1777 struct request_queue *q = rq->q;
1778 bool run_queue = true;
1779
1780 /*
1781 * RCU or SRCU read lock is needed before checking quiesced flag.
1782 *
1783 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1784 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1785 * and avoid driver to try to dispatch again.
1786 */
1787 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
1788 run_queue = false;
1789 bypass_insert = false;
1790 goto insert;
1791 }
1792
1793 if (q->elevator && !bypass_insert)
1794 goto insert;
1795
1796 if (!blk_mq_get_dispatch_budget(hctx))
1797 goto insert;
1798
1799 if (!blk_mq_get_driver_tag(rq, NULL, false)) {
1800 blk_mq_put_dispatch_budget(hctx);
1801 goto insert;
1802 }
1803
1804 return __blk_mq_issue_directly(hctx, rq, cookie);
1805insert:
1806 if (bypass_insert)
1807 return BLK_STS_RESOURCE;
1808
1809 blk_mq_sched_insert_request(rq, false, run_queue, false);
1810 return BLK_STS_OK;
1811}
1812
1813static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1814 struct request *rq, blk_qc_t *cookie)
1815{
1816 blk_status_t ret;
1817 int srcu_idx;
1818
1819 might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
1820
1821 hctx_lock(hctx, &srcu_idx);
1822
1823 ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);
1824 if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
1825 blk_mq_sched_insert_request(rq, false, true, false);
1826 else if (ret != BLK_STS_OK)
1827 blk_mq_end_request(rq, ret);
1828
1829 hctx_unlock(hctx, srcu_idx);
1830}
1831
1832blk_status_t blk_mq_request_issue_directly(struct request *rq)
1833{
1834 blk_status_t ret;
1835 int srcu_idx;
1836 blk_qc_t unused_cookie;
1837 struct blk_mq_ctx *ctx = rq->mq_ctx;
1838 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(rq->q, ctx->cpu);
1839
1840 hctx_lock(hctx, &srcu_idx);
1841 ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true);
1842 hctx_unlock(hctx, srcu_idx);
1843
1844 return ret;
1845}
1846
1847static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1848{
1849 const int is_sync = op_is_sync(bio->bi_opf);
1850 const int is_flush_fua = op_is_flush(bio->bi_opf);
1851 struct blk_mq_alloc_data data = { .flags = 0 };
1852 struct request *rq;
1853 unsigned int request_count = 0;
1854 struct blk_plug *plug;
1855 struct request *same_queue_rq = NULL;
1856 blk_qc_t cookie;
1857 unsigned int wb_acct;
1858
1859 blk_queue_bounce(q, &bio);
1860
1861 blk_queue_split(q, &bio);
1862
1863 if (!bio_integrity_prep(bio))
1864 return BLK_QC_T_NONE;
1865
1866 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1867 blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1868 return BLK_QC_T_NONE;
1869
1870 if (blk_mq_sched_bio_merge(q, bio))
1871 return BLK_QC_T_NONE;
1872
1873 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1874
1875 trace_block_getrq(q, bio, bio->bi_opf);
1876
1877 rq = blk_mq_get_request(q, bio, bio->bi_opf, &data);
1878 if (unlikely(!rq)) {
1879 __wbt_done(q->rq_wb, wb_acct);
1880 if (bio->bi_opf & REQ_NOWAIT)
1881 bio_wouldblock_error(bio);
1882 return BLK_QC_T_NONE;
1883 }
1884
1885 wbt_track(&rq->issue_stat, wb_acct);
1886
1887 cookie = request_to_qc_t(data.hctx, rq);
1888
1889 plug = current->plug;
1890 if (unlikely(is_flush_fua)) {
1891 blk_mq_put_ctx(data.ctx);
1892 blk_mq_bio_to_request(rq, bio);
1893
1894 /* bypass scheduler for flush rq */
1895 blk_insert_flush(rq);
1896 blk_mq_run_hw_queue(data.hctx, true);
1897 } else if (plug && q->nr_hw_queues == 1) {
1898 struct request *last = NULL;
1899
1900 blk_mq_put_ctx(data.ctx);
1901 blk_mq_bio_to_request(rq, bio);
1902
1903 /*
1904 * @request_count may become stale because of schedule
1905 * out, so check the list again.
1906 */
1907 if (list_empty(&plug->mq_list))
1908 request_count = 0;
1909 else if (blk_queue_nomerges(q))
1910 request_count = blk_plug_queued_count(q);
1911
1912 if (!request_count)
1913 trace_block_plug(q);
1914 else
1915 last = list_entry_rq(plug->mq_list.prev);
1916
1917 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1918 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1919 blk_flush_plug_list(plug, false);
1920 trace_block_plug(q);
1921 }
1922
1923 list_add_tail(&rq->queuelist, &plug->mq_list);
1924 } else if (plug && !blk_queue_nomerges(q)) {
1925 blk_mq_bio_to_request(rq, bio);
1926
1927 /*
1928 * We do limited plugging. If the bio can be merged, do that.
1929 * Otherwise the existing request in the plug list will be
1930 * issued. So the plug list will have one request at most
1931 * The plug list might get flushed before this. If that happens,
1932 * the plug list is empty, and same_queue_rq is invalid.
1933 */
1934 if (list_empty(&plug->mq_list))
1935 same_queue_rq = NULL;
1936 if (same_queue_rq)
1937 list_del_init(&same_queue_rq->queuelist);
1938 list_add_tail(&rq->queuelist, &plug->mq_list);
1939
1940 blk_mq_put_ctx(data.ctx);
1941
1942 if (same_queue_rq) {
1943 data.hctx = blk_mq_map_queue(q,
1944 same_queue_rq->mq_ctx->cpu);
1945 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
1946 &cookie);
1947 }
1948 } else if (q->nr_hw_queues > 1 && is_sync) {
1949 blk_mq_put_ctx(data.ctx);
1950 blk_mq_bio_to_request(rq, bio);
1951 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
1952 } else if (q->elevator) {
1953 blk_mq_put_ctx(data.ctx);
1954 blk_mq_bio_to_request(rq, bio);
1955 blk_mq_sched_insert_request(rq, false, true, true);
1956 } else {
1957 blk_mq_put_ctx(data.ctx);
1958 blk_mq_bio_to_request(rq, bio);
1959 blk_mq_queue_io(data.hctx, data.ctx, rq);
1960 blk_mq_run_hw_queue(data.hctx, true);
1961 }
1962
1963 return cookie;
1964}
1965
1966void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1967 unsigned int hctx_idx)
1968{
1969 struct page *page;
1970
1971 if (tags->rqs && set->ops->exit_request) {
1972 int i;
1973
1974 for (i = 0; i < tags->nr_tags; i++) {
1975 struct request *rq = tags->static_rqs[i];
1976
1977 if (!rq)
1978 continue;
1979 set->ops->exit_request(set, rq, hctx_idx);
1980 tags->static_rqs[i] = NULL;
1981 }
1982 }
1983
1984 while (!list_empty(&tags->page_list)) {
1985 page = list_first_entry(&tags->page_list, struct page, lru);
1986 list_del_init(&page->lru);
1987 /*
1988 * Remove kmemleak object previously allocated in
1989 * blk_mq_init_rq_map().
1990 */
1991 kmemleak_free(page_address(page));
1992 __free_pages(page, page->private);
1993 }
1994}
1995
1996void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1997{
1998 kfree(tags->rqs);
1999 tags->rqs = NULL;
2000 kfree(tags->static_rqs);
2001 tags->static_rqs = NULL;
2002
2003 blk_mq_free_tags(tags);
2004}
2005
2006struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
2007 unsigned int hctx_idx,
2008 unsigned int nr_tags,
2009 unsigned int reserved_tags)
2010{
2011 struct blk_mq_tags *tags;
2012 int node;
2013
2014 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
2015 if (node == NUMA_NO_NODE)
2016 node = set->numa_node;
2017
2018 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
2019 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
2020 if (!tags)
2021 return NULL;
2022
2023 tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
2024 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2025 node);
2026 if (!tags->rqs) {
2027 blk_mq_free_tags(tags);
2028 return NULL;
2029 }
2030
2031 tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
2032 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
2033 node);
2034 if (!tags->static_rqs) {
2035 kfree(tags->rqs);
2036 blk_mq_free_tags(tags);
2037 return NULL;
2038 }
2039
2040 return tags;
2041}
2042
2043static size_t order_to_size(unsigned int order)
2044{
2045 return (size_t)PAGE_SIZE << order;
2046}
2047
2048static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
2049 unsigned int hctx_idx, int node)
2050{
2051 int ret;
2052
2053 if (set->ops->init_request) {
2054 ret = set->ops->init_request(set, rq, hctx_idx, node);
2055 if (ret)
2056 return ret;
2057 }
2058
2059 seqcount_init(&rq->gstate_seq);
2060 u64_stats_init(&rq->aborted_gstate_sync);
2061 /*
2062 * start gstate with gen 1 instead of 0, otherwise it will be equal
2063 * to aborted_gstate, and be identified timed out by
2064 * blk_mq_terminate_expired.
2065 */
2066 WRITE_ONCE(rq->gstate, MQ_RQ_GEN_INC);
2067
2068 return 0;
2069}
2070
2071int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
2072 unsigned int hctx_idx, unsigned int depth)
2073{
2074 unsigned int i, j, entries_per_page, max_order = 4;
2075 size_t rq_size, left;
2076 int node;
2077
2078 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
2079 if (node == NUMA_NO_NODE)
2080 node = set->numa_node;
2081
2082 INIT_LIST_HEAD(&tags->page_list);
2083
2084 /*
2085 * rq_size is the size of the request plus driver payload, rounded
2086 * to the cacheline size
2087 */
2088 rq_size = round_up(sizeof(struct request) + set->cmd_size,
2089 cache_line_size());
2090 left = rq_size * depth;
2091
2092 for (i = 0; i < depth; ) {
2093 int this_order = max_order;
2094 struct page *page;
2095 int to_do;
2096 void *p;
2097
2098 while (this_order && left < order_to_size(this_order - 1))
2099 this_order--;
2100
2101 do {
2102 page = alloc_pages_node(node,
2103 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
2104 this_order);
2105 if (page)
2106 break;
2107 if (!this_order--)
2108 break;
2109 if (order_to_size(this_order) < rq_size)
2110 break;
2111 } while (1);
2112
2113 if (!page)
2114 goto fail;
2115
2116 page->private = this_order;
2117 list_add_tail(&page->lru, &tags->page_list);
2118
2119 p = page_address(page);
2120 /*
2121 * Allow kmemleak to scan these pages as they contain pointers
2122 * to additional allocations like via ops->init_request().
2123 */
2124 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
2125 entries_per_page = order_to_size(this_order) / rq_size;
2126 to_do = min(entries_per_page, depth - i);
2127 left -= to_do * rq_size;
2128 for (j = 0; j < to_do; j++) {
2129 struct request *rq = p;
2130
2131 tags->static_rqs[i] = rq;
2132 if (blk_mq_init_request(set, rq, hctx_idx, node)) {
2133 tags->static_rqs[i] = NULL;
2134 goto fail;
2135 }
2136
2137 p += rq_size;
2138 i++;
2139 }
2140 }
2141 return 0;
2142
2143fail:
2144 blk_mq_free_rqs(set, tags, hctx_idx);
2145 return -ENOMEM;
2146}
2147
2148/*
2149 * 'cpu' is going away. splice any existing rq_list entries from this
2150 * software queue to the hw queue dispatch list, and ensure that it
2151 * gets run.
2152 */
2153static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
2154{
2155 struct blk_mq_hw_ctx *hctx;
2156 struct blk_mq_ctx *ctx;
2157 LIST_HEAD(tmp);
2158
2159 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
2160 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
2161
2162 spin_lock(&ctx->lock);
2163 if (!list_empty(&ctx->rq_list)) {
2164 list_splice_init(&ctx->rq_list, &tmp);
2165 blk_mq_hctx_clear_pending(hctx, ctx);
2166 }
2167 spin_unlock(&ctx->lock);
2168
2169 if (list_empty(&tmp))
2170 return 0;
2171
2172 spin_lock(&hctx->lock);
2173 list_splice_tail_init(&tmp, &hctx->dispatch);
2174 spin_unlock(&hctx->lock);
2175
2176 blk_mq_run_hw_queue(hctx, true);
2177 return 0;
2178}
2179
2180static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
2181{
2182 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
2183 &hctx->cpuhp_dead);
2184}
2185
2186/* hctx->ctxs will be freed in queue's release handler */
2187static void blk_mq_exit_hctx(struct request_queue *q,
2188 struct blk_mq_tag_set *set,
2189 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
2190{
2191 blk_mq_debugfs_unregister_hctx(hctx);
2192
2193 if (blk_mq_hw_queue_mapped(hctx))
2194 blk_mq_tag_idle(hctx);
2195
2196 if (set->ops->exit_request)
2197 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
2198
2199 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
2200
2201 if (set->ops->exit_hctx)
2202 set->ops->exit_hctx(hctx, hctx_idx);
2203
2204 if (hctx->flags & BLK_MQ_F_BLOCKING)
2205 cleanup_srcu_struct(hctx->srcu);
2206
2207 blk_mq_remove_cpuhp(hctx);
2208 blk_free_flush_queue(hctx->fq);
2209 sbitmap_free(&hctx->ctx_map);
2210}
2211
2212static void blk_mq_exit_hw_queues(struct request_queue *q,
2213 struct blk_mq_tag_set *set, int nr_queue)
2214{
2215 struct blk_mq_hw_ctx *hctx;
2216 unsigned int i;
2217
2218 queue_for_each_hw_ctx(q, hctx, i) {
2219 if (i == nr_queue)
2220 break;
2221 blk_mq_exit_hctx(q, set, hctx, i);
2222 }
2223}
2224
2225static int blk_mq_init_hctx(struct request_queue *q,
2226 struct blk_mq_tag_set *set,
2227 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
2228{
2229 int node;
2230
2231 node = hctx->numa_node;
2232 if (node == NUMA_NO_NODE)
2233 node = hctx->numa_node = set->numa_node;
2234
2235 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
2236 spin_lock_init(&hctx->lock);
2237 INIT_LIST_HEAD(&hctx->dispatch);
2238 hctx->queue = q;
2239 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
2240
2241 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
2242
2243 hctx->tags = set->tags[hctx_idx];
2244
2245 /*
2246 * Allocate space for all possible cpus to avoid allocation at
2247 * runtime
2248 */
2249 hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
2250 GFP_KERNEL, node);
2251 if (!hctx->ctxs)
2252 goto unregister_cpu_notifier;
2253
2254 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
2255 node))
2256 goto free_ctxs;
2257
2258 hctx->nr_ctx = 0;
2259
2260 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
2261 INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
2262
2263 if (set->ops->init_hctx &&
2264 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
2265 goto free_bitmap;
2266
2267 if (blk_mq_sched_init_hctx(q, hctx, hctx_idx))
2268 goto exit_hctx;
2269
2270 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
2271 if (!hctx->fq)
2272 goto sched_exit_hctx;
2273
2274 if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx, node))
2275 goto free_fq;
2276
2277 if (hctx->flags & BLK_MQ_F_BLOCKING)
2278 init_srcu_struct(hctx->srcu);
2279
2280 blk_mq_debugfs_register_hctx(q, hctx);
2281
2282 return 0;
2283
2284 free_fq:
2285 kfree(hctx->fq);
2286 sched_exit_hctx:
2287 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
2288 exit_hctx:
2289 if (set->ops->exit_hctx)
2290 set->ops->exit_hctx(hctx, hctx_idx);
2291 free_bitmap:
2292 sbitmap_free(&hctx->ctx_map);
2293 free_ctxs:
2294 kfree(hctx->ctxs);
2295 unregister_cpu_notifier:
2296 blk_mq_remove_cpuhp(hctx);
2297 return -1;
2298}
2299
2300static void blk_mq_init_cpu_queues(struct request_queue *q,
2301 unsigned int nr_hw_queues)
2302{
2303 unsigned int i;
2304
2305 for_each_possible_cpu(i) {
2306 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2307 struct blk_mq_hw_ctx *hctx;
2308
2309 __ctx->cpu = i;
2310 spin_lock_init(&__ctx->lock);
2311 INIT_LIST_HEAD(&__ctx->rq_list);
2312 __ctx->queue = q;
2313
2314 /*
2315 * Set local node, IFF we have more than one hw queue. If
2316 * not, we remain on the home node of the device
2317 */
2318 hctx = blk_mq_map_queue(q, i);
2319 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2320 hctx->numa_node = local_memory_node(cpu_to_node(i));
2321 }
2322}
2323
2324static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2325{
2326 int ret = 0;
2327
2328 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2329 set->queue_depth, set->reserved_tags);
2330 if (!set->tags[hctx_idx])
2331 return false;
2332
2333 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2334 set->queue_depth);
2335 if (!ret)
2336 return true;
2337
2338 blk_mq_free_rq_map(set->tags[hctx_idx]);
2339 set->tags[hctx_idx] = NULL;
2340 return false;
2341}
2342
2343static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2344 unsigned int hctx_idx)
2345{
2346 if (set->tags[hctx_idx]) {
2347 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2348 blk_mq_free_rq_map(set->tags[hctx_idx]);
2349 set->tags[hctx_idx] = NULL;
2350 }
2351}
2352
2353static void blk_mq_map_swqueue(struct request_queue *q)
2354{
2355 unsigned int i, hctx_idx;
2356 struct blk_mq_hw_ctx *hctx;
2357 struct blk_mq_ctx *ctx;
2358 struct blk_mq_tag_set *set = q->tag_set;
2359
2360 /*
2361 * Avoid others reading imcomplete hctx->cpumask through sysfs
2362 */
2363 mutex_lock(&q->sysfs_lock);
2364
2365 queue_for_each_hw_ctx(q, hctx, i) {
2366 cpumask_clear(hctx->cpumask);
2367 hctx->nr_ctx = 0;
2368 }
2369
2370 /*
2371 * Map software to hardware queues.
2372 *
2373 * If the cpu isn't present, the cpu is mapped to first hctx.
2374 */
2375 for_each_possible_cpu(i) {
2376 hctx_idx = q->mq_map[i];
2377 /* unmapped hw queue can be remapped after CPU topo changed */
2378 if (!set->tags[hctx_idx] &&
2379 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2380 /*
2381 * If tags initialization fail for some hctx,
2382 * that hctx won't be brought online. In this
2383 * case, remap the current ctx to hctx[0] which
2384 * is guaranteed to always have tags allocated
2385 */
2386 q->mq_map[i] = 0;
2387 }
2388
2389 ctx = per_cpu_ptr(q->queue_ctx, i);
2390 hctx = blk_mq_map_queue(q, i);
2391
2392 cpumask_set_cpu(i, hctx->cpumask);
2393 ctx->index_hw = hctx->nr_ctx;
2394 hctx->ctxs[hctx->nr_ctx++] = ctx;
2395 }
2396
2397 mutex_unlock(&q->sysfs_lock);
2398
2399 queue_for_each_hw_ctx(q, hctx, i) {
2400 /*
2401 * If no software queues are mapped to this hardware queue,
2402 * disable it and free the request entries.
2403 */
2404 if (!hctx->nr_ctx) {
2405 /* Never unmap queue 0. We need it as a
2406 * fallback in case of a new remap fails
2407 * allocation
2408 */
2409 if (i && set->tags[i])
2410 blk_mq_free_map_and_requests(set, i);
2411
2412 hctx->tags = NULL;
2413 continue;
2414 }
2415
2416 hctx->tags = set->tags[i];
2417 WARN_ON(!hctx->tags);
2418
2419 /*
2420 * Set the map size to the number of mapped software queues.
2421 * This is more accurate and more efficient than looping
2422 * over all possibly mapped software queues.
2423 */
2424 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2425
2426 /*
2427 * Initialize batch roundrobin counts
2428 */
2429 hctx->next_cpu = blk_mq_first_mapped_cpu(hctx);
2430 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2431 }
2432}
2433
2434/*
2435 * Caller needs to ensure that we're either frozen/quiesced, or that
2436 * the queue isn't live yet.
2437 */
2438static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2439{
2440 struct blk_mq_hw_ctx *hctx;
2441 int i;
2442
2443 queue_for_each_hw_ctx(q, hctx, i) {
2444 if (shared) {
2445 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2446 atomic_inc(&q->shared_hctx_restart);
2447 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2448 } else {
2449 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2450 atomic_dec(&q->shared_hctx_restart);
2451 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2452 }
2453 }
2454}
2455
2456static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set,
2457 bool shared)
2458{
2459 struct request_queue *q;
2460
2461 lockdep_assert_held(&set->tag_list_lock);
2462
2463 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2464 blk_mq_freeze_queue(q);
2465 queue_set_hctx_shared(q, shared);
2466 blk_mq_unfreeze_queue(q);
2467 }
2468}
2469
2470static void blk_mq_del_queue_tag_set(struct request_queue *q)
2471{
2472 struct blk_mq_tag_set *set = q->tag_set;
2473
2474 mutex_lock(&set->tag_list_lock);
2475 list_del_rcu(&q->tag_set_list);
2476 INIT_LIST_HEAD(&q->tag_set_list);
2477 if (list_is_singular(&set->tag_list)) {
2478 /* just transitioned to unshared */
2479 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2480 /* update existing queue */
2481 blk_mq_update_tag_set_depth(set, false);
2482 }
2483 mutex_unlock(&set->tag_list_lock);
2484
2485 synchronize_rcu();
2486}
2487
2488static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2489 struct request_queue *q)
2490{
2491 q->tag_set = set;
2492
2493 mutex_lock(&set->tag_list_lock);
2494
2495 /*
2496 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2497 */
2498 if (!list_empty(&set->tag_list) &&
2499 !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2500 set->flags |= BLK_MQ_F_TAG_SHARED;
2501 /* update existing queue */
2502 blk_mq_update_tag_set_depth(set, true);
2503 }
2504 if (set->flags & BLK_MQ_F_TAG_SHARED)
2505 queue_set_hctx_shared(q, true);
2506 list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
2507
2508 mutex_unlock(&set->tag_list_lock);
2509}
2510
2511/*
2512 * It is the actual release handler for mq, but we do it from
2513 * request queue's release handler for avoiding use-after-free
2514 * and headache because q->mq_kobj shouldn't have been introduced,
2515 * but we can't group ctx/kctx kobj without it.
2516 */
2517void blk_mq_release(struct request_queue *q)
2518{
2519 struct blk_mq_hw_ctx *hctx;
2520 unsigned int i;
2521
2522 /* hctx kobj stays in hctx */
2523 queue_for_each_hw_ctx(q, hctx, i) {
2524 if (!hctx)
2525 continue;
2526 kobject_put(&hctx->kobj);
2527 }
2528
2529 q->mq_map = NULL;
2530
2531 kfree(q->queue_hw_ctx);
2532
2533 /*
2534 * release .mq_kobj and sw queue's kobject now because
2535 * both share lifetime with request queue.
2536 */
2537 blk_mq_sysfs_deinit(q);
2538
2539 free_percpu(q->queue_ctx);
2540}
2541
2542struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2543{
2544 struct request_queue *uninit_q, *q;
2545
2546 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node, NULL);
2547 if (!uninit_q)
2548 return ERR_PTR(-ENOMEM);
2549
2550 q = blk_mq_init_allocated_queue(set, uninit_q);
2551 if (IS_ERR(q))
2552 blk_cleanup_queue(uninit_q);
2553
2554 return q;
2555}
2556EXPORT_SYMBOL(blk_mq_init_queue);
2557
2558static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2559{
2560 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2561
2562 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
2563 __alignof__(struct blk_mq_hw_ctx)) !=
2564 sizeof(struct blk_mq_hw_ctx));
2565
2566 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2567 hw_ctx_size += sizeof(struct srcu_struct);
2568
2569 return hw_ctx_size;
2570}
2571
2572static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2573 struct request_queue *q)
2574{
2575 int i, j;
2576 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2577
2578 blk_mq_sysfs_unregister(q);
2579
2580 /* protect against switching io scheduler */
2581 mutex_lock(&q->sysfs_lock);
2582 for (i = 0; i < set->nr_hw_queues; i++) {
2583 int node;
2584
2585 if (hctxs[i])
2586 continue;
2587
2588 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2589 hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set),
2590 GFP_KERNEL, node);
2591 if (!hctxs[i])
2592 break;
2593
2594 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2595 node)) {
2596 kfree(hctxs[i]);
2597 hctxs[i] = NULL;
2598 break;
2599 }
2600
2601 atomic_set(&hctxs[i]->nr_active, 0);
2602 hctxs[i]->numa_node = node;
2603 hctxs[i]->queue_num = i;
2604
2605 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2606 free_cpumask_var(hctxs[i]->cpumask);
2607 kfree(hctxs[i]);
2608 hctxs[i] = NULL;
2609 break;
2610 }
2611 blk_mq_hctx_kobj_init(hctxs[i]);
2612 }
2613 for (j = i; j < q->nr_hw_queues; j++) {
2614 struct blk_mq_hw_ctx *hctx = hctxs[j];
2615
2616 if (hctx) {
2617 if (hctx->tags)
2618 blk_mq_free_map_and_requests(set, j);
2619 blk_mq_exit_hctx(q, set, hctx, j);
2620 kobject_put(&hctx->kobj);
2621 hctxs[j] = NULL;
2622
2623 }
2624 }
2625 q->nr_hw_queues = i;
2626 mutex_unlock(&q->sysfs_lock);
2627 blk_mq_sysfs_register(q);
2628}
2629
2630struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2631 struct request_queue *q)
2632{
2633 /* mark the queue as mq asap */
2634 q->mq_ops = set->ops;
2635
2636 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2637 blk_mq_poll_stats_bkt,
2638 BLK_MQ_POLL_STATS_BKTS, q);
2639 if (!q->poll_cb)
2640 goto err_exit;
2641
2642 q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2643 if (!q->queue_ctx)
2644 goto err_exit;
2645
2646 /* init q->mq_kobj and sw queues' kobjects */
2647 blk_mq_sysfs_init(q);
2648
2649 q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2650 GFP_KERNEL, set->numa_node);
2651 if (!q->queue_hw_ctx)
2652 goto err_percpu;
2653
2654 q->mq_map = set->mq_map;
2655
2656 blk_mq_realloc_hw_ctxs(set, q);
2657 if (!q->nr_hw_queues)
2658 goto err_hctxs;
2659
2660 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2661 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2662
2663 q->nr_queues = nr_cpu_ids;
2664
2665 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2666
2667 if (!(set->flags & BLK_MQ_F_SG_MERGE))
2668 queue_flag_set_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);
2669
2670 q->sg_reserved_size = INT_MAX;
2671
2672 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2673 INIT_LIST_HEAD(&q->requeue_list);
2674 spin_lock_init(&q->requeue_lock);
2675
2676 blk_queue_make_request(q, blk_mq_make_request);
2677 if (q->mq_ops->poll)
2678 q->poll_fn = blk_mq_poll;
2679
2680 /*
2681 * Do this after blk_queue_make_request() overrides it...
2682 */
2683 q->nr_requests = set->queue_depth;
2684
2685 /*
2686 * Default to classic polling
2687 */
2688 q->poll_nsec = -1;
2689
2690 if (set->ops->complete)
2691 blk_queue_softirq_done(q, set->ops->complete);
2692
2693 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2694 blk_mq_add_queue_tag_set(set, q);
2695 blk_mq_map_swqueue(q);
2696
2697 if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2698 int ret;
2699
2700 ret = blk_mq_sched_init(q);
2701 if (ret)
2702 return ERR_PTR(ret);
2703 }
2704
2705 return q;
2706
2707err_hctxs:
2708 kfree(q->queue_hw_ctx);
2709err_percpu:
2710 free_percpu(q->queue_ctx);
2711err_exit:
2712 q->mq_ops = NULL;
2713 return ERR_PTR(-ENOMEM);
2714}
2715EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2716
2717void blk_mq_free_queue(struct request_queue *q)
2718{
2719 struct blk_mq_tag_set *set = q->tag_set;
2720
2721 blk_mq_del_queue_tag_set(q);
2722 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2723}
2724
2725/* Basically redo blk_mq_init_queue with queue frozen */
2726static void blk_mq_queue_reinit(struct request_queue *q)
2727{
2728 WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2729
2730 blk_mq_debugfs_unregister_hctxs(q);
2731 blk_mq_sysfs_unregister(q);
2732
2733 /*
2734 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2735 * we should change hctx numa_node according to the new topology (this
2736 * involves freeing and re-allocating memory, worth doing?)
2737 */
2738 blk_mq_map_swqueue(q);
2739
2740 blk_mq_sysfs_register(q);
2741 blk_mq_debugfs_register_hctxs(q);
2742}
2743
2744static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2745{
2746 int i;
2747
2748 for (i = 0; i < set->nr_hw_queues; i++)
2749 if (!__blk_mq_alloc_rq_map(set, i))
2750 goto out_unwind;
2751
2752 return 0;
2753
2754out_unwind:
2755 while (--i >= 0)
2756 blk_mq_free_rq_map(set->tags[i]);
2757
2758 return -ENOMEM;
2759}
2760
2761/*
2762 * Allocate the request maps associated with this tag_set. Note that this
2763 * may reduce the depth asked for, if memory is tight. set->queue_depth
2764 * will be updated to reflect the allocated depth.
2765 */
2766static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2767{
2768 unsigned int depth;
2769 int err;
2770
2771 depth = set->queue_depth;
2772 do {
2773 err = __blk_mq_alloc_rq_maps(set);
2774 if (!err)
2775 break;
2776
2777 set->queue_depth >>= 1;
2778 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2779 err = -ENOMEM;
2780 break;
2781 }
2782 } while (set->queue_depth);
2783
2784 if (!set->queue_depth || err) {
2785 pr_err("blk-mq: failed to allocate request map\n");
2786 return -ENOMEM;
2787 }
2788
2789 if (depth != set->queue_depth)
2790 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2791 depth, set->queue_depth);
2792
2793 return 0;
2794}
2795
2796static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
2797{
2798 if (set->ops->map_queues) {
2799 int cpu;
2800 /*
2801 * transport .map_queues is usually done in the following
2802 * way:
2803 *
2804 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
2805 * mask = get_cpu_mask(queue)
2806 * for_each_cpu(cpu, mask)
2807 * set->mq_map[cpu] = queue;
2808 * }
2809 *
2810 * When we need to remap, the table has to be cleared for
2811 * killing stale mapping since one CPU may not be mapped
2812 * to any hw queue.
2813 */
2814 for_each_possible_cpu(cpu)
2815 set->mq_map[cpu] = 0;
2816
2817 return set->ops->map_queues(set);
2818 } else
2819 return blk_mq_map_queues(set);
2820}
2821
2822/*
2823 * Alloc a tag set to be associated with one or more request queues.
2824 * May fail with EINVAL for various error conditions. May adjust the
2825 * requested depth down, if if it too large. In that case, the set
2826 * value will be stored in set->queue_depth.
2827 */
2828int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2829{
2830 int ret;
2831
2832 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2833
2834 if (!set->nr_hw_queues)
2835 return -EINVAL;
2836 if (!set->queue_depth)
2837 return -EINVAL;
2838 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2839 return -EINVAL;
2840
2841 if (!set->ops->queue_rq)
2842 return -EINVAL;
2843
2844 if (!set->ops->get_budget ^ !set->ops->put_budget)
2845 return -EINVAL;
2846
2847 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2848 pr_info("blk-mq: reduced tag depth to %u\n",
2849 BLK_MQ_MAX_DEPTH);
2850 set->queue_depth = BLK_MQ_MAX_DEPTH;
2851 }
2852
2853 /*
2854 * If a crashdump is active, then we are potentially in a very
2855 * memory constrained environment. Limit us to 1 queue and
2856 * 64 tags to prevent using too much memory.
2857 */
2858 if (is_kdump_kernel()) {
2859 set->nr_hw_queues = 1;
2860 set->queue_depth = min(64U, set->queue_depth);
2861 }
2862 /*
2863 * There is no use for more h/w queues than cpus.
2864 */
2865 if (set->nr_hw_queues > nr_cpu_ids)
2866 set->nr_hw_queues = nr_cpu_ids;
2867
2868 set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2869 GFP_KERNEL, set->numa_node);
2870 if (!set->tags)
2871 return -ENOMEM;
2872
2873 ret = -ENOMEM;
2874 set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2875 GFP_KERNEL, set->numa_node);
2876 if (!set->mq_map)
2877 goto out_free_tags;
2878
2879 ret = blk_mq_update_queue_map(set);
2880 if (ret)
2881 goto out_free_mq_map;
2882
2883 ret = blk_mq_alloc_rq_maps(set);
2884 if (ret)
2885 goto out_free_mq_map;
2886
2887 mutex_init(&set->tag_list_lock);
2888 INIT_LIST_HEAD(&set->tag_list);
2889
2890 return 0;
2891
2892out_free_mq_map:
2893 kfree(set->mq_map);
2894 set->mq_map = NULL;
2895out_free_tags:
2896 kfree(set->tags);
2897 set->tags = NULL;
2898 return ret;
2899}
2900EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2901
2902void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2903{
2904 int i;
2905
2906 for (i = 0; i < nr_cpu_ids; i++)
2907 blk_mq_free_map_and_requests(set, i);
2908
2909 kfree(set->mq_map);
2910 set->mq_map = NULL;
2911
2912 kfree(set->tags);
2913 set->tags = NULL;
2914}
2915EXPORT_SYMBOL(blk_mq_free_tag_set);
2916
2917int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2918{
2919 struct blk_mq_tag_set *set = q->tag_set;
2920 struct blk_mq_hw_ctx *hctx;
2921 int i, ret;
2922
2923 if (!set)
2924 return -EINVAL;
2925
2926 blk_mq_freeze_queue(q);
2927 blk_mq_quiesce_queue(q);
2928
2929 ret = 0;
2930 queue_for_each_hw_ctx(q, hctx, i) {
2931 if (!hctx->tags)
2932 continue;
2933 /*
2934 * If we're using an MQ scheduler, just update the scheduler
2935 * queue depth. This is similar to what the old code would do.
2936 */
2937 if (!hctx->sched_tags) {
2938 ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
2939 false);
2940 } else {
2941 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2942 nr, true);
2943 }
2944 if (ret)
2945 break;
2946 }
2947
2948 if (!ret)
2949 q->nr_requests = nr;
2950
2951 blk_mq_unquiesce_queue(q);
2952 blk_mq_unfreeze_queue(q);
2953
2954 return ret;
2955}
2956
2957static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
2958 int nr_hw_queues)
2959{
2960 struct request_queue *q;
2961
2962 lockdep_assert_held(&set->tag_list_lock);
2963
2964 if (nr_hw_queues > nr_cpu_ids)
2965 nr_hw_queues = nr_cpu_ids;
2966 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2967 return;
2968
2969 list_for_each_entry(q, &set->tag_list, tag_set_list)
2970 blk_mq_freeze_queue(q);
2971
2972 set->nr_hw_queues = nr_hw_queues;
2973 blk_mq_update_queue_map(set);
2974 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2975 blk_mq_realloc_hw_ctxs(set, q);
2976 blk_mq_queue_reinit(q);
2977 }
2978
2979 list_for_each_entry(q, &set->tag_list, tag_set_list)
2980 blk_mq_unfreeze_queue(q);
2981}
2982
2983void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2984{
2985 mutex_lock(&set->tag_list_lock);
2986 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
2987 mutex_unlock(&set->tag_list_lock);
2988}
2989EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2990
2991/* Enable polling stats and return whether they were already enabled. */
2992static bool blk_poll_stats_enable(struct request_queue *q)
2993{
2994 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2995 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
2996 return true;
2997 blk_stat_add_callback(q, q->poll_cb);
2998 return false;
2999}
3000
3001static void blk_mq_poll_stats_start(struct request_queue *q)
3002{
3003 /*
3004 * We don't arm the callback if polling stats are not enabled or the
3005 * callback is already active.
3006 */
3007 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
3008 blk_stat_is_active(q->poll_cb))
3009 return;
3010
3011 blk_stat_activate_msecs(q->poll_cb, 100);
3012}
3013
3014static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
3015{
3016 struct request_queue *q = cb->data;
3017 int bucket;
3018
3019 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
3020 if (cb->stat[bucket].nr_samples)
3021 q->poll_stat[bucket] = cb->stat[bucket];
3022 }
3023}
3024
3025static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
3026 struct blk_mq_hw_ctx *hctx,
3027 struct request *rq)
3028{
3029 unsigned long ret = 0;
3030 int bucket;
3031
3032 /*
3033 * If stats collection isn't on, don't sleep but turn it on for
3034 * future users
3035 */
3036 if (!blk_poll_stats_enable(q))
3037 return 0;
3038
3039 /*
3040 * As an optimistic guess, use half of the mean service time
3041 * for this type of request. We can (and should) make this smarter.
3042 * For instance, if the completion latencies are tight, we can
3043 * get closer than just half the mean. This is especially
3044 * important on devices where the completion latencies are longer
3045 * than ~10 usec. We do use the stats for the relevant IO size
3046 * if available which does lead to better estimates.
3047 */
3048 bucket = blk_mq_poll_stats_bkt(rq);
3049 if (bucket < 0)
3050 return ret;
3051
3052 if (q->poll_stat[bucket].nr_samples)
3053 ret = (q->poll_stat[bucket].mean + 1) / 2;
3054
3055 return ret;
3056}
3057
3058static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
3059 struct blk_mq_hw_ctx *hctx,
3060 struct request *rq)
3061{
3062 struct hrtimer_sleeper hs;
3063 enum hrtimer_mode mode;
3064 unsigned int nsecs;
3065 ktime_t kt;
3066
3067 if (rq->rq_flags & RQF_MQ_POLL_SLEPT)
3068 return false;
3069
3070 /*
3071 * poll_nsec can be:
3072 *
3073 * -1: don't ever hybrid sleep
3074 * 0: use half of prev avg
3075 * >0: use this specific value
3076 */
3077 if (q->poll_nsec == -1)
3078 return false;
3079 else if (q->poll_nsec > 0)
3080 nsecs = q->poll_nsec;
3081 else
3082 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
3083
3084 if (!nsecs)
3085 return false;
3086
3087 rq->rq_flags |= RQF_MQ_POLL_SLEPT;
3088
3089 /*
3090 * This will be replaced with the stats tracking code, using
3091 * 'avg_completion_time / 2' as the pre-sleep target.
3092 */
3093 kt = nsecs;
3094
3095 mode = HRTIMER_MODE_REL;
3096 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
3097 hrtimer_set_expires(&hs.timer, kt);
3098
3099 hrtimer_init_sleeper(&hs, current);
3100 do {
3101 if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
3102 break;
3103 set_current_state(TASK_UNINTERRUPTIBLE);
3104 hrtimer_start_expires(&hs.timer, mode);
3105 if (hs.task)
3106 io_schedule();
3107 hrtimer_cancel(&hs.timer);
3108 mode = HRTIMER_MODE_ABS;
3109 } while (hs.task && !signal_pending(current));
3110
3111 __set_current_state(TASK_RUNNING);
3112 destroy_hrtimer_on_stack(&hs.timer);
3113 return true;
3114}
3115
3116static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
3117{
3118 struct request_queue *q = hctx->queue;
3119 long state;
3120
3121 /*
3122 * If we sleep, have the caller restart the poll loop to reset
3123 * the state. Like for the other success return cases, the
3124 * caller is responsible for checking if the IO completed. If
3125 * the IO isn't complete, we'll get called again and will go
3126 * straight to the busy poll loop.
3127 */
3128 if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
3129 return true;
3130
3131 hctx->poll_considered++;
3132
3133 state = current->state;
3134 while (!need_resched()) {
3135 int ret;
3136
3137 hctx->poll_invoked++;
3138
3139 ret = q->mq_ops->poll(hctx, rq->tag);
3140 if (ret > 0) {
3141 hctx->poll_success++;
3142 set_current_state(TASK_RUNNING);
3143 return true;
3144 }
3145
3146 if (signal_pending_state(state, current))
3147 set_current_state(TASK_RUNNING);
3148
3149 if (current->state == TASK_RUNNING)
3150 return true;
3151 if (ret < 0)
3152 break;
3153 cpu_relax();
3154 }
3155
3156 __set_current_state(TASK_RUNNING);
3157 return false;
3158}
3159
3160static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
3161{
3162 struct blk_mq_hw_ctx *hctx;
3163 struct request *rq;
3164
3165 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
3166 return false;
3167
3168 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
3169 if (!blk_qc_t_is_internal(cookie))
3170 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
3171 else {
3172 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
3173 /*
3174 * With scheduling, if the request has completed, we'll
3175 * get a NULL return here, as we clear the sched tag when
3176 * that happens. The request still remains valid, like always,
3177 * so we should be safe with just the NULL check.
3178 */
3179 if (!rq)
3180 return false;
3181 }
3182
3183 return __blk_mq_poll(hctx, rq);
3184}
3185
3186static int __init blk_mq_init(void)
3187{
3188 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
3189 blk_mq_hctx_notify_dead);
3190 return 0;
3191}
3192subsys_initcall(blk_mq_init);
1/*
2 * Block multiqueue core code
3 *
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
6 */
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <linux/backing-dev.h>
10#include <linux/bio.h>
11#include <linux/blkdev.h>
12#include <linux/kmemleak.h>
13#include <linux/mm.h>
14#include <linux/init.h>
15#include <linux/slab.h>
16#include <linux/workqueue.h>
17#include <linux/smp.h>
18#include <linux/llist.h>
19#include <linux/list_sort.h>
20#include <linux/cpu.h>
21#include <linux/cache.h>
22#include <linux/sched/sysctl.h>
23#include <linux/delay.h>
24#include <linux/crash_dump.h>
25
26#include <trace/events/block.h>
27
28#include <linux/blk-mq.h>
29#include "blk.h"
30#include "blk-mq.h"
31#include "blk-mq-tag.h"
32
33static DEFINE_MUTEX(all_q_mutex);
34static LIST_HEAD(all_q_list);
35
36static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
37
38/*
39 * Check if any of the ctx's have pending work in this hardware queue
40 */
41static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
42{
43 unsigned int i;
44
45 for (i = 0; i < hctx->ctx_map.size; i++)
46 if (hctx->ctx_map.map[i].word)
47 return true;
48
49 return false;
50}
51
52static inline struct blk_align_bitmap *get_bm(struct blk_mq_hw_ctx *hctx,
53 struct blk_mq_ctx *ctx)
54{
55 return &hctx->ctx_map.map[ctx->index_hw / hctx->ctx_map.bits_per_word];
56}
57
58#define CTX_TO_BIT(hctx, ctx) \
59 ((ctx)->index_hw & ((hctx)->ctx_map.bits_per_word - 1))
60
61/*
62 * Mark this ctx as having pending work in this hardware queue
63 */
64static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
65 struct blk_mq_ctx *ctx)
66{
67 struct blk_align_bitmap *bm = get_bm(hctx, ctx);
68
69 if (!test_bit(CTX_TO_BIT(hctx, ctx), &bm->word))
70 set_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
71}
72
73static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
74 struct blk_mq_ctx *ctx)
75{
76 struct blk_align_bitmap *bm = get_bm(hctx, ctx);
77
78 clear_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
79}
80
81void blk_mq_freeze_queue_start(struct request_queue *q)
82{
83 int freeze_depth;
84
85 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
86 if (freeze_depth == 1) {
87 percpu_ref_kill(&q->q_usage_counter);
88 blk_mq_run_hw_queues(q, false);
89 }
90}
91EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
92
93static void blk_mq_freeze_queue_wait(struct request_queue *q)
94{
95 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
96}
97
98/*
99 * Guarantee no request is in use, so we can change any data structure of
100 * the queue afterward.
101 */
102void blk_freeze_queue(struct request_queue *q)
103{
104 /*
105 * In the !blk_mq case we are only calling this to kill the
106 * q_usage_counter, otherwise this increases the freeze depth
107 * and waits for it to return to zero. For this reason there is
108 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
109 * exported to drivers as the only user for unfreeze is blk_mq.
110 */
111 blk_mq_freeze_queue_start(q);
112 blk_mq_freeze_queue_wait(q);
113}
114
115void blk_mq_freeze_queue(struct request_queue *q)
116{
117 /*
118 * ...just an alias to keep freeze and unfreeze actions balanced
119 * in the blk_mq_* namespace
120 */
121 blk_freeze_queue(q);
122}
123EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
124
125void blk_mq_unfreeze_queue(struct request_queue *q)
126{
127 int freeze_depth;
128
129 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
130 WARN_ON_ONCE(freeze_depth < 0);
131 if (!freeze_depth) {
132 percpu_ref_reinit(&q->q_usage_counter);
133 wake_up_all(&q->mq_freeze_wq);
134 }
135}
136EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
137
138void blk_mq_wake_waiters(struct request_queue *q)
139{
140 struct blk_mq_hw_ctx *hctx;
141 unsigned int i;
142
143 queue_for_each_hw_ctx(q, hctx, i)
144 if (blk_mq_hw_queue_mapped(hctx))
145 blk_mq_tag_wakeup_all(hctx->tags, true);
146
147 /*
148 * If we are called because the queue has now been marked as
149 * dying, we need to ensure that processes currently waiting on
150 * the queue are notified as well.
151 */
152 wake_up_all(&q->mq_freeze_wq);
153}
154
155bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
156{
157 return blk_mq_has_free_tags(hctx->tags);
158}
159EXPORT_SYMBOL(blk_mq_can_queue);
160
161static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
162 struct request *rq, unsigned int rw_flags)
163{
164 if (blk_queue_io_stat(q))
165 rw_flags |= REQ_IO_STAT;
166
167 INIT_LIST_HEAD(&rq->queuelist);
168 /* csd/requeue_work/fifo_time is initialized before use */
169 rq->q = q;
170 rq->mq_ctx = ctx;
171 rq->cmd_flags |= rw_flags;
172 /* do not touch atomic flags, it needs atomic ops against the timer */
173 rq->cpu = -1;
174 INIT_HLIST_NODE(&rq->hash);
175 RB_CLEAR_NODE(&rq->rb_node);
176 rq->rq_disk = NULL;
177 rq->part = NULL;
178 rq->start_time = jiffies;
179#ifdef CONFIG_BLK_CGROUP
180 rq->rl = NULL;
181 set_start_time_ns(rq);
182 rq->io_start_time_ns = 0;
183#endif
184 rq->nr_phys_segments = 0;
185#if defined(CONFIG_BLK_DEV_INTEGRITY)
186 rq->nr_integrity_segments = 0;
187#endif
188 rq->special = NULL;
189 /* tag was already set */
190 rq->errors = 0;
191
192 rq->cmd = rq->__cmd;
193
194 rq->extra_len = 0;
195 rq->sense_len = 0;
196 rq->resid_len = 0;
197 rq->sense = NULL;
198
199 INIT_LIST_HEAD(&rq->timeout_list);
200 rq->timeout = 0;
201
202 rq->end_io = NULL;
203 rq->end_io_data = NULL;
204 rq->next_rq = NULL;
205
206 ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
207}
208
209static struct request *
210__blk_mq_alloc_request(struct blk_mq_alloc_data *data, int rw)
211{
212 struct request *rq;
213 unsigned int tag;
214
215 tag = blk_mq_get_tag(data);
216 if (tag != BLK_MQ_TAG_FAIL) {
217 rq = data->hctx->tags->rqs[tag];
218
219 if (blk_mq_tag_busy(data->hctx)) {
220 rq->cmd_flags = REQ_MQ_INFLIGHT;
221 atomic_inc(&data->hctx->nr_active);
222 }
223
224 rq->tag = tag;
225 blk_mq_rq_ctx_init(data->q, data->ctx, rq, rw);
226 return rq;
227 }
228
229 return NULL;
230}
231
232struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
233 unsigned int flags)
234{
235 struct blk_mq_ctx *ctx;
236 struct blk_mq_hw_ctx *hctx;
237 struct request *rq;
238 struct blk_mq_alloc_data alloc_data;
239 int ret;
240
241 ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
242 if (ret)
243 return ERR_PTR(ret);
244
245 ctx = blk_mq_get_ctx(q);
246 hctx = q->mq_ops->map_queue(q, ctx->cpu);
247 blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
248
249 rq = __blk_mq_alloc_request(&alloc_data, rw);
250 if (!rq && !(flags & BLK_MQ_REQ_NOWAIT)) {
251 __blk_mq_run_hw_queue(hctx);
252 blk_mq_put_ctx(ctx);
253
254 ctx = blk_mq_get_ctx(q);
255 hctx = q->mq_ops->map_queue(q, ctx->cpu);
256 blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
257 rq = __blk_mq_alloc_request(&alloc_data, rw);
258 ctx = alloc_data.ctx;
259 }
260 blk_mq_put_ctx(ctx);
261 if (!rq) {
262 blk_queue_exit(q);
263 return ERR_PTR(-EWOULDBLOCK);
264 }
265 return rq;
266}
267EXPORT_SYMBOL(blk_mq_alloc_request);
268
269static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
270 struct blk_mq_ctx *ctx, struct request *rq)
271{
272 const int tag = rq->tag;
273 struct request_queue *q = rq->q;
274
275 if (rq->cmd_flags & REQ_MQ_INFLIGHT)
276 atomic_dec(&hctx->nr_active);
277 rq->cmd_flags = 0;
278
279 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
280 blk_mq_put_tag(hctx, tag, &ctx->last_tag);
281 blk_queue_exit(q);
282}
283
284void blk_mq_free_hctx_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
285{
286 struct blk_mq_ctx *ctx = rq->mq_ctx;
287
288 ctx->rq_completed[rq_is_sync(rq)]++;
289 __blk_mq_free_request(hctx, ctx, rq);
290
291}
292EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request);
293
294void blk_mq_free_request(struct request *rq)
295{
296 struct blk_mq_hw_ctx *hctx;
297 struct request_queue *q = rq->q;
298
299 hctx = q->mq_ops->map_queue(q, rq->mq_ctx->cpu);
300 blk_mq_free_hctx_request(hctx, rq);
301}
302EXPORT_SYMBOL_GPL(blk_mq_free_request);
303
304inline void __blk_mq_end_request(struct request *rq, int error)
305{
306 blk_account_io_done(rq);
307
308 if (rq->end_io) {
309 rq->end_io(rq, error);
310 } else {
311 if (unlikely(blk_bidi_rq(rq)))
312 blk_mq_free_request(rq->next_rq);
313 blk_mq_free_request(rq);
314 }
315}
316EXPORT_SYMBOL(__blk_mq_end_request);
317
318void blk_mq_end_request(struct request *rq, int error)
319{
320 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
321 BUG();
322 __blk_mq_end_request(rq, error);
323}
324EXPORT_SYMBOL(blk_mq_end_request);
325
326static void __blk_mq_complete_request_remote(void *data)
327{
328 struct request *rq = data;
329
330 rq->q->softirq_done_fn(rq);
331}
332
333static void blk_mq_ipi_complete_request(struct request *rq)
334{
335 struct blk_mq_ctx *ctx = rq->mq_ctx;
336 bool shared = false;
337 int cpu;
338
339 if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
340 rq->q->softirq_done_fn(rq);
341 return;
342 }
343
344 cpu = get_cpu();
345 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
346 shared = cpus_share_cache(cpu, ctx->cpu);
347
348 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
349 rq->csd.func = __blk_mq_complete_request_remote;
350 rq->csd.info = rq;
351 rq->csd.flags = 0;
352 smp_call_function_single_async(ctx->cpu, &rq->csd);
353 } else {
354 rq->q->softirq_done_fn(rq);
355 }
356 put_cpu();
357}
358
359static void __blk_mq_complete_request(struct request *rq)
360{
361 struct request_queue *q = rq->q;
362
363 if (!q->softirq_done_fn)
364 blk_mq_end_request(rq, rq->errors);
365 else
366 blk_mq_ipi_complete_request(rq);
367}
368
369/**
370 * blk_mq_complete_request - end I/O on a request
371 * @rq: the request being processed
372 *
373 * Description:
374 * Ends all I/O on a request. It does not handle partial completions.
375 * The actual completion happens out-of-order, through a IPI handler.
376 **/
377void blk_mq_complete_request(struct request *rq, int error)
378{
379 struct request_queue *q = rq->q;
380
381 if (unlikely(blk_should_fake_timeout(q)))
382 return;
383 if (!blk_mark_rq_complete(rq)) {
384 rq->errors = error;
385 __blk_mq_complete_request(rq);
386 }
387}
388EXPORT_SYMBOL(blk_mq_complete_request);
389
390int blk_mq_request_started(struct request *rq)
391{
392 return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
393}
394EXPORT_SYMBOL_GPL(blk_mq_request_started);
395
396void blk_mq_start_request(struct request *rq)
397{
398 struct request_queue *q = rq->q;
399
400 trace_block_rq_issue(q, rq);
401
402 rq->resid_len = blk_rq_bytes(rq);
403 if (unlikely(blk_bidi_rq(rq)))
404 rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
405
406 blk_add_timer(rq);
407
408 /*
409 * Ensure that ->deadline is visible before set the started
410 * flag and clear the completed flag.
411 */
412 smp_mb__before_atomic();
413
414 /*
415 * Mark us as started and clear complete. Complete might have been
416 * set if requeue raced with timeout, which then marked it as
417 * complete. So be sure to clear complete again when we start
418 * the request, otherwise we'll ignore the completion event.
419 */
420 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
421 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
422 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
423 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
424
425 if (q->dma_drain_size && blk_rq_bytes(rq)) {
426 /*
427 * Make sure space for the drain appears. We know we can do
428 * this because max_hw_segments has been adjusted to be one
429 * fewer than the device can handle.
430 */
431 rq->nr_phys_segments++;
432 }
433}
434EXPORT_SYMBOL(blk_mq_start_request);
435
436static void __blk_mq_requeue_request(struct request *rq)
437{
438 struct request_queue *q = rq->q;
439
440 trace_block_rq_requeue(q, rq);
441
442 if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
443 if (q->dma_drain_size && blk_rq_bytes(rq))
444 rq->nr_phys_segments--;
445 }
446}
447
448void blk_mq_requeue_request(struct request *rq)
449{
450 __blk_mq_requeue_request(rq);
451
452 BUG_ON(blk_queued_rq(rq));
453 blk_mq_add_to_requeue_list(rq, true);
454}
455EXPORT_SYMBOL(blk_mq_requeue_request);
456
457static void blk_mq_requeue_work(struct work_struct *work)
458{
459 struct request_queue *q =
460 container_of(work, struct request_queue, requeue_work);
461 LIST_HEAD(rq_list);
462 struct request *rq, *next;
463 unsigned long flags;
464
465 spin_lock_irqsave(&q->requeue_lock, flags);
466 list_splice_init(&q->requeue_list, &rq_list);
467 spin_unlock_irqrestore(&q->requeue_lock, flags);
468
469 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
470 if (!(rq->cmd_flags & REQ_SOFTBARRIER))
471 continue;
472
473 rq->cmd_flags &= ~REQ_SOFTBARRIER;
474 list_del_init(&rq->queuelist);
475 blk_mq_insert_request(rq, true, false, false);
476 }
477
478 while (!list_empty(&rq_list)) {
479 rq = list_entry(rq_list.next, struct request, queuelist);
480 list_del_init(&rq->queuelist);
481 blk_mq_insert_request(rq, false, false, false);
482 }
483
484 /*
485 * Use the start variant of queue running here, so that running
486 * the requeue work will kick stopped queues.
487 */
488 blk_mq_start_hw_queues(q);
489}
490
491void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
492{
493 struct request_queue *q = rq->q;
494 unsigned long flags;
495
496 /*
497 * We abuse this flag that is otherwise used by the I/O scheduler to
498 * request head insertation from the workqueue.
499 */
500 BUG_ON(rq->cmd_flags & REQ_SOFTBARRIER);
501
502 spin_lock_irqsave(&q->requeue_lock, flags);
503 if (at_head) {
504 rq->cmd_flags |= REQ_SOFTBARRIER;
505 list_add(&rq->queuelist, &q->requeue_list);
506 } else {
507 list_add_tail(&rq->queuelist, &q->requeue_list);
508 }
509 spin_unlock_irqrestore(&q->requeue_lock, flags);
510}
511EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
512
513void blk_mq_cancel_requeue_work(struct request_queue *q)
514{
515 cancel_work_sync(&q->requeue_work);
516}
517EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work);
518
519void blk_mq_kick_requeue_list(struct request_queue *q)
520{
521 kblockd_schedule_work(&q->requeue_work);
522}
523EXPORT_SYMBOL(blk_mq_kick_requeue_list);
524
525void blk_mq_abort_requeue_list(struct request_queue *q)
526{
527 unsigned long flags;
528 LIST_HEAD(rq_list);
529
530 spin_lock_irqsave(&q->requeue_lock, flags);
531 list_splice_init(&q->requeue_list, &rq_list);
532 spin_unlock_irqrestore(&q->requeue_lock, flags);
533
534 while (!list_empty(&rq_list)) {
535 struct request *rq;
536
537 rq = list_first_entry(&rq_list, struct request, queuelist);
538 list_del_init(&rq->queuelist);
539 rq->errors = -EIO;
540 blk_mq_end_request(rq, rq->errors);
541 }
542}
543EXPORT_SYMBOL(blk_mq_abort_requeue_list);
544
545struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
546{
547 if (tag < tags->nr_tags)
548 return tags->rqs[tag];
549
550 return NULL;
551}
552EXPORT_SYMBOL(blk_mq_tag_to_rq);
553
554struct blk_mq_timeout_data {
555 unsigned long next;
556 unsigned int next_set;
557};
558
559void blk_mq_rq_timed_out(struct request *req, bool reserved)
560{
561 struct blk_mq_ops *ops = req->q->mq_ops;
562 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
563
564 /*
565 * We know that complete is set at this point. If STARTED isn't set
566 * anymore, then the request isn't active and the "timeout" should
567 * just be ignored. This can happen due to the bitflag ordering.
568 * Timeout first checks if STARTED is set, and if it is, assumes
569 * the request is active. But if we race with completion, then
570 * we both flags will get cleared. So check here again, and ignore
571 * a timeout event with a request that isn't active.
572 */
573 if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
574 return;
575
576 if (ops->timeout)
577 ret = ops->timeout(req, reserved);
578
579 switch (ret) {
580 case BLK_EH_HANDLED:
581 __blk_mq_complete_request(req);
582 break;
583 case BLK_EH_RESET_TIMER:
584 blk_add_timer(req);
585 blk_clear_rq_complete(req);
586 break;
587 case BLK_EH_NOT_HANDLED:
588 break;
589 default:
590 printk(KERN_ERR "block: bad eh return: %d\n", ret);
591 break;
592 }
593}
594
595static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
596 struct request *rq, void *priv, bool reserved)
597{
598 struct blk_mq_timeout_data *data = priv;
599
600 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
601 /*
602 * If a request wasn't started before the queue was
603 * marked dying, kill it here or it'll go unnoticed.
604 */
605 if (unlikely(blk_queue_dying(rq->q))) {
606 rq->errors = -EIO;
607 blk_mq_end_request(rq, rq->errors);
608 }
609 return;
610 }
611
612 if (time_after_eq(jiffies, rq->deadline)) {
613 if (!blk_mark_rq_complete(rq))
614 blk_mq_rq_timed_out(rq, reserved);
615 } else if (!data->next_set || time_after(data->next, rq->deadline)) {
616 data->next = rq->deadline;
617 data->next_set = 1;
618 }
619}
620
621static void blk_mq_timeout_work(struct work_struct *work)
622{
623 struct request_queue *q =
624 container_of(work, struct request_queue, timeout_work);
625 struct blk_mq_timeout_data data = {
626 .next = 0,
627 .next_set = 0,
628 };
629 int i;
630
631 if (blk_queue_enter(q, true))
632 return;
633
634 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
635
636 if (data.next_set) {
637 data.next = blk_rq_timeout(round_jiffies_up(data.next));
638 mod_timer(&q->timeout, data.next);
639 } else {
640 struct blk_mq_hw_ctx *hctx;
641
642 queue_for_each_hw_ctx(q, hctx, i) {
643 /* the hctx may be unmapped, so check it here */
644 if (blk_mq_hw_queue_mapped(hctx))
645 blk_mq_tag_idle(hctx);
646 }
647 }
648 blk_queue_exit(q);
649}
650
651/*
652 * Reverse check our software queue for entries that we could potentially
653 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
654 * too much time checking for merges.
655 */
656static bool blk_mq_attempt_merge(struct request_queue *q,
657 struct blk_mq_ctx *ctx, struct bio *bio)
658{
659 struct request *rq;
660 int checked = 8;
661
662 list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
663 int el_ret;
664
665 if (!checked--)
666 break;
667
668 if (!blk_rq_merge_ok(rq, bio))
669 continue;
670
671 el_ret = blk_try_merge(rq, bio);
672 if (el_ret == ELEVATOR_BACK_MERGE) {
673 if (bio_attempt_back_merge(q, rq, bio)) {
674 ctx->rq_merged++;
675 return true;
676 }
677 break;
678 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
679 if (bio_attempt_front_merge(q, rq, bio)) {
680 ctx->rq_merged++;
681 return true;
682 }
683 break;
684 }
685 }
686
687 return false;
688}
689
690/*
691 * Process software queues that have been marked busy, splicing them
692 * to the for-dispatch
693 */
694static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
695{
696 struct blk_mq_ctx *ctx;
697 int i;
698
699 for (i = 0; i < hctx->ctx_map.size; i++) {
700 struct blk_align_bitmap *bm = &hctx->ctx_map.map[i];
701 unsigned int off, bit;
702
703 if (!bm->word)
704 continue;
705
706 bit = 0;
707 off = i * hctx->ctx_map.bits_per_word;
708 do {
709 bit = find_next_bit(&bm->word, bm->depth, bit);
710 if (bit >= bm->depth)
711 break;
712
713 ctx = hctx->ctxs[bit + off];
714 clear_bit(bit, &bm->word);
715 spin_lock(&ctx->lock);
716 list_splice_tail_init(&ctx->rq_list, list);
717 spin_unlock(&ctx->lock);
718
719 bit++;
720 } while (1);
721 }
722}
723
724/*
725 * Run this hardware queue, pulling any software queues mapped to it in.
726 * Note that this function currently has various problems around ordering
727 * of IO. In particular, we'd like FIFO behaviour on handling existing
728 * items on the hctx->dispatch list. Ignore that for now.
729 */
730static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
731{
732 struct request_queue *q = hctx->queue;
733 struct request *rq;
734 LIST_HEAD(rq_list);
735 LIST_HEAD(driver_list);
736 struct list_head *dptr;
737 int queued;
738
739 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask));
740
741 if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
742 return;
743
744 hctx->run++;
745
746 /*
747 * Touch any software queue that has pending entries.
748 */
749 flush_busy_ctxs(hctx, &rq_list);
750
751 /*
752 * If we have previous entries on our dispatch list, grab them
753 * and stuff them at the front for more fair dispatch.
754 */
755 if (!list_empty_careful(&hctx->dispatch)) {
756 spin_lock(&hctx->lock);
757 if (!list_empty(&hctx->dispatch))
758 list_splice_init(&hctx->dispatch, &rq_list);
759 spin_unlock(&hctx->lock);
760 }
761
762 /*
763 * Start off with dptr being NULL, so we start the first request
764 * immediately, even if we have more pending.
765 */
766 dptr = NULL;
767
768 /*
769 * Now process all the entries, sending them to the driver.
770 */
771 queued = 0;
772 while (!list_empty(&rq_list)) {
773 struct blk_mq_queue_data bd;
774 int ret;
775
776 rq = list_first_entry(&rq_list, struct request, queuelist);
777 list_del_init(&rq->queuelist);
778
779 bd.rq = rq;
780 bd.list = dptr;
781 bd.last = list_empty(&rq_list);
782
783 ret = q->mq_ops->queue_rq(hctx, &bd);
784 switch (ret) {
785 case BLK_MQ_RQ_QUEUE_OK:
786 queued++;
787 continue;
788 case BLK_MQ_RQ_QUEUE_BUSY:
789 list_add(&rq->queuelist, &rq_list);
790 __blk_mq_requeue_request(rq);
791 break;
792 default:
793 pr_err("blk-mq: bad return on queue: %d\n", ret);
794 case BLK_MQ_RQ_QUEUE_ERROR:
795 rq->errors = -EIO;
796 blk_mq_end_request(rq, rq->errors);
797 break;
798 }
799
800 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
801 break;
802
803 /*
804 * We've done the first request. If we have more than 1
805 * left in the list, set dptr to defer issue.
806 */
807 if (!dptr && rq_list.next != rq_list.prev)
808 dptr = &driver_list;
809 }
810
811 if (!queued)
812 hctx->dispatched[0]++;
813 else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
814 hctx->dispatched[ilog2(queued) + 1]++;
815
816 /*
817 * Any items that need requeuing? Stuff them into hctx->dispatch,
818 * that is where we will continue on next queue run.
819 */
820 if (!list_empty(&rq_list)) {
821 spin_lock(&hctx->lock);
822 list_splice(&rq_list, &hctx->dispatch);
823 spin_unlock(&hctx->lock);
824 /*
825 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
826 * it's possible the queue is stopped and restarted again
827 * before this. Queue restart will dispatch requests. And since
828 * requests in rq_list aren't added into hctx->dispatch yet,
829 * the requests in rq_list might get lost.
830 *
831 * blk_mq_run_hw_queue() already checks the STOPPED bit
832 **/
833 blk_mq_run_hw_queue(hctx, true);
834 }
835}
836
837/*
838 * It'd be great if the workqueue API had a way to pass
839 * in a mask and had some smarts for more clever placement.
840 * For now we just round-robin here, switching for every
841 * BLK_MQ_CPU_WORK_BATCH queued items.
842 */
843static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
844{
845 if (hctx->queue->nr_hw_queues == 1)
846 return WORK_CPU_UNBOUND;
847
848 if (--hctx->next_cpu_batch <= 0) {
849 int cpu = hctx->next_cpu, next_cpu;
850
851 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
852 if (next_cpu >= nr_cpu_ids)
853 next_cpu = cpumask_first(hctx->cpumask);
854
855 hctx->next_cpu = next_cpu;
856 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
857
858 return cpu;
859 }
860
861 return hctx->next_cpu;
862}
863
864void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
865{
866 if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state) ||
867 !blk_mq_hw_queue_mapped(hctx)))
868 return;
869
870 if (!async) {
871 int cpu = get_cpu();
872 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
873 __blk_mq_run_hw_queue(hctx);
874 put_cpu();
875 return;
876 }
877
878 put_cpu();
879 }
880
881 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
882 &hctx->run_work, 0);
883}
884
885void blk_mq_run_hw_queues(struct request_queue *q, bool async)
886{
887 struct blk_mq_hw_ctx *hctx;
888 int i;
889
890 queue_for_each_hw_ctx(q, hctx, i) {
891 if ((!blk_mq_hctx_has_pending(hctx) &&
892 list_empty_careful(&hctx->dispatch)) ||
893 test_bit(BLK_MQ_S_STOPPED, &hctx->state))
894 continue;
895
896 blk_mq_run_hw_queue(hctx, async);
897 }
898}
899EXPORT_SYMBOL(blk_mq_run_hw_queues);
900
901void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
902{
903 cancel_delayed_work(&hctx->run_work);
904 cancel_delayed_work(&hctx->delay_work);
905 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
906}
907EXPORT_SYMBOL(blk_mq_stop_hw_queue);
908
909void blk_mq_stop_hw_queues(struct request_queue *q)
910{
911 struct blk_mq_hw_ctx *hctx;
912 int i;
913
914 queue_for_each_hw_ctx(q, hctx, i)
915 blk_mq_stop_hw_queue(hctx);
916}
917EXPORT_SYMBOL(blk_mq_stop_hw_queues);
918
919void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
920{
921 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
922
923 blk_mq_run_hw_queue(hctx, false);
924}
925EXPORT_SYMBOL(blk_mq_start_hw_queue);
926
927void blk_mq_start_hw_queues(struct request_queue *q)
928{
929 struct blk_mq_hw_ctx *hctx;
930 int i;
931
932 queue_for_each_hw_ctx(q, hctx, i)
933 blk_mq_start_hw_queue(hctx);
934}
935EXPORT_SYMBOL(blk_mq_start_hw_queues);
936
937void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
938{
939 struct blk_mq_hw_ctx *hctx;
940 int i;
941
942 queue_for_each_hw_ctx(q, hctx, i) {
943 if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
944 continue;
945
946 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
947 blk_mq_run_hw_queue(hctx, async);
948 }
949}
950EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
951
952static void blk_mq_run_work_fn(struct work_struct *work)
953{
954 struct blk_mq_hw_ctx *hctx;
955
956 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
957
958 __blk_mq_run_hw_queue(hctx);
959}
960
961static void blk_mq_delay_work_fn(struct work_struct *work)
962{
963 struct blk_mq_hw_ctx *hctx;
964
965 hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
966
967 if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
968 __blk_mq_run_hw_queue(hctx);
969}
970
971void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
972{
973 if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
974 return;
975
976 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
977 &hctx->delay_work, msecs_to_jiffies(msecs));
978}
979EXPORT_SYMBOL(blk_mq_delay_queue);
980
981static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
982 struct blk_mq_ctx *ctx,
983 struct request *rq,
984 bool at_head)
985{
986 trace_block_rq_insert(hctx->queue, rq);
987
988 if (at_head)
989 list_add(&rq->queuelist, &ctx->rq_list);
990 else
991 list_add_tail(&rq->queuelist, &ctx->rq_list);
992}
993
994static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
995 struct request *rq, bool at_head)
996{
997 struct blk_mq_ctx *ctx = rq->mq_ctx;
998
999 __blk_mq_insert_req_list(hctx, ctx, rq, at_head);
1000 blk_mq_hctx_mark_pending(hctx, ctx);
1001}
1002
1003void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
1004 bool async)
1005{
1006 struct request_queue *q = rq->q;
1007 struct blk_mq_hw_ctx *hctx;
1008 struct blk_mq_ctx *ctx = rq->mq_ctx, *current_ctx;
1009
1010 current_ctx = blk_mq_get_ctx(q);
1011 if (!cpu_online(ctx->cpu))
1012 rq->mq_ctx = ctx = current_ctx;
1013
1014 hctx = q->mq_ops->map_queue(q, ctx->cpu);
1015
1016 spin_lock(&ctx->lock);
1017 __blk_mq_insert_request(hctx, rq, at_head);
1018 spin_unlock(&ctx->lock);
1019
1020 if (run_queue)
1021 blk_mq_run_hw_queue(hctx, async);
1022
1023 blk_mq_put_ctx(current_ctx);
1024}
1025
1026static void blk_mq_insert_requests(struct request_queue *q,
1027 struct blk_mq_ctx *ctx,
1028 struct list_head *list,
1029 int depth,
1030 bool from_schedule)
1031
1032{
1033 struct blk_mq_hw_ctx *hctx;
1034 struct blk_mq_ctx *current_ctx;
1035
1036 trace_block_unplug(q, depth, !from_schedule);
1037
1038 current_ctx = blk_mq_get_ctx(q);
1039
1040 if (!cpu_online(ctx->cpu))
1041 ctx = current_ctx;
1042 hctx = q->mq_ops->map_queue(q, ctx->cpu);
1043
1044 /*
1045 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1046 * offline now
1047 */
1048 spin_lock(&ctx->lock);
1049 while (!list_empty(list)) {
1050 struct request *rq;
1051
1052 rq = list_first_entry(list, struct request, queuelist);
1053 list_del_init(&rq->queuelist);
1054 rq->mq_ctx = ctx;
1055 __blk_mq_insert_req_list(hctx, ctx, rq, false);
1056 }
1057 blk_mq_hctx_mark_pending(hctx, ctx);
1058 spin_unlock(&ctx->lock);
1059
1060 blk_mq_run_hw_queue(hctx, from_schedule);
1061 blk_mq_put_ctx(current_ctx);
1062}
1063
1064static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1065{
1066 struct request *rqa = container_of(a, struct request, queuelist);
1067 struct request *rqb = container_of(b, struct request, queuelist);
1068
1069 return !(rqa->mq_ctx < rqb->mq_ctx ||
1070 (rqa->mq_ctx == rqb->mq_ctx &&
1071 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1072}
1073
1074void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1075{
1076 struct blk_mq_ctx *this_ctx;
1077 struct request_queue *this_q;
1078 struct request *rq;
1079 LIST_HEAD(list);
1080 LIST_HEAD(ctx_list);
1081 unsigned int depth;
1082
1083 list_splice_init(&plug->mq_list, &list);
1084
1085 list_sort(NULL, &list, plug_ctx_cmp);
1086
1087 this_q = NULL;
1088 this_ctx = NULL;
1089 depth = 0;
1090
1091 while (!list_empty(&list)) {
1092 rq = list_entry_rq(list.next);
1093 list_del_init(&rq->queuelist);
1094 BUG_ON(!rq->q);
1095 if (rq->mq_ctx != this_ctx) {
1096 if (this_ctx) {
1097 blk_mq_insert_requests(this_q, this_ctx,
1098 &ctx_list, depth,
1099 from_schedule);
1100 }
1101
1102 this_ctx = rq->mq_ctx;
1103 this_q = rq->q;
1104 depth = 0;
1105 }
1106
1107 depth++;
1108 list_add_tail(&rq->queuelist, &ctx_list);
1109 }
1110
1111 /*
1112 * If 'this_ctx' is set, we know we have entries to complete
1113 * on 'ctx_list'. Do those.
1114 */
1115 if (this_ctx) {
1116 blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
1117 from_schedule);
1118 }
1119}
1120
1121static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1122{
1123 init_request_from_bio(rq, bio);
1124
1125 if (blk_do_io_stat(rq))
1126 blk_account_io_start(rq, 1);
1127}
1128
1129static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1130{
1131 return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1132 !blk_queue_nomerges(hctx->queue);
1133}
1134
1135static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1136 struct blk_mq_ctx *ctx,
1137 struct request *rq, struct bio *bio)
1138{
1139 if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
1140 blk_mq_bio_to_request(rq, bio);
1141 spin_lock(&ctx->lock);
1142insert_rq:
1143 __blk_mq_insert_request(hctx, rq, false);
1144 spin_unlock(&ctx->lock);
1145 return false;
1146 } else {
1147 struct request_queue *q = hctx->queue;
1148
1149 spin_lock(&ctx->lock);
1150 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1151 blk_mq_bio_to_request(rq, bio);
1152 goto insert_rq;
1153 }
1154
1155 spin_unlock(&ctx->lock);
1156 __blk_mq_free_request(hctx, ctx, rq);
1157 return true;
1158 }
1159}
1160
1161struct blk_map_ctx {
1162 struct blk_mq_hw_ctx *hctx;
1163 struct blk_mq_ctx *ctx;
1164};
1165
1166static struct request *blk_mq_map_request(struct request_queue *q,
1167 struct bio *bio,
1168 struct blk_map_ctx *data)
1169{
1170 struct blk_mq_hw_ctx *hctx;
1171 struct blk_mq_ctx *ctx;
1172 struct request *rq;
1173 int rw = bio_data_dir(bio);
1174 struct blk_mq_alloc_data alloc_data;
1175
1176 blk_queue_enter_live(q);
1177 ctx = blk_mq_get_ctx(q);
1178 hctx = q->mq_ops->map_queue(q, ctx->cpu);
1179
1180 if (rw_is_sync(bio->bi_rw))
1181 rw |= REQ_SYNC;
1182
1183 trace_block_getrq(q, bio, rw);
1184 blk_mq_set_alloc_data(&alloc_data, q, BLK_MQ_REQ_NOWAIT, ctx, hctx);
1185 rq = __blk_mq_alloc_request(&alloc_data, rw);
1186 if (unlikely(!rq)) {
1187 __blk_mq_run_hw_queue(hctx);
1188 blk_mq_put_ctx(ctx);
1189 trace_block_sleeprq(q, bio, rw);
1190
1191 ctx = blk_mq_get_ctx(q);
1192 hctx = q->mq_ops->map_queue(q, ctx->cpu);
1193 blk_mq_set_alloc_data(&alloc_data, q, 0, ctx, hctx);
1194 rq = __blk_mq_alloc_request(&alloc_data, rw);
1195 ctx = alloc_data.ctx;
1196 hctx = alloc_data.hctx;
1197 }
1198
1199 hctx->queued++;
1200 data->hctx = hctx;
1201 data->ctx = ctx;
1202 return rq;
1203}
1204
1205static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie)
1206{
1207 int ret;
1208 struct request_queue *q = rq->q;
1209 struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q,
1210 rq->mq_ctx->cpu);
1211 struct blk_mq_queue_data bd = {
1212 .rq = rq,
1213 .list = NULL,
1214 .last = 1
1215 };
1216 blk_qc_t new_cookie = blk_tag_to_qc_t(rq->tag, hctx->queue_num);
1217
1218 /*
1219 * For OK queue, we are done. For error, kill it. Any other
1220 * error (busy), just add it to our list as we previously
1221 * would have done
1222 */
1223 ret = q->mq_ops->queue_rq(hctx, &bd);
1224 if (ret == BLK_MQ_RQ_QUEUE_OK) {
1225 *cookie = new_cookie;
1226 return 0;
1227 }
1228
1229 __blk_mq_requeue_request(rq);
1230
1231 if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1232 *cookie = BLK_QC_T_NONE;
1233 rq->errors = -EIO;
1234 blk_mq_end_request(rq, rq->errors);
1235 return 0;
1236 }
1237
1238 return -1;
1239}
1240
1241/*
1242 * Multiple hardware queue variant. This will not use per-process plugs,
1243 * but will attempt to bypass the hctx queueing if we can go straight to
1244 * hardware for SYNC IO.
1245 */
1246static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1247{
1248 const int is_sync = rw_is_sync(bio->bi_rw);
1249 const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
1250 struct blk_map_ctx data;
1251 struct request *rq;
1252 unsigned int request_count = 0;
1253 struct blk_plug *plug;
1254 struct request *same_queue_rq = NULL;
1255 blk_qc_t cookie;
1256
1257 blk_queue_bounce(q, &bio);
1258
1259 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1260 bio_io_error(bio);
1261 return BLK_QC_T_NONE;
1262 }
1263
1264 blk_queue_split(q, &bio, q->bio_split);
1265
1266 if (!is_flush_fua && !blk_queue_nomerges(q)) {
1267 if (blk_attempt_plug_merge(q, bio, &request_count,
1268 &same_queue_rq))
1269 return BLK_QC_T_NONE;
1270 } else
1271 request_count = blk_plug_queued_count(q);
1272
1273 rq = blk_mq_map_request(q, bio, &data);
1274 if (unlikely(!rq))
1275 return BLK_QC_T_NONE;
1276
1277 cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
1278
1279 if (unlikely(is_flush_fua)) {
1280 blk_mq_bio_to_request(rq, bio);
1281 blk_insert_flush(rq);
1282 goto run_queue;
1283 }
1284
1285 plug = current->plug;
1286 /*
1287 * If the driver supports defer issued based on 'last', then
1288 * queue it up like normal since we can potentially save some
1289 * CPU this way.
1290 */
1291 if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
1292 !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
1293 struct request *old_rq = NULL;
1294
1295 blk_mq_bio_to_request(rq, bio);
1296
1297 /*
1298 * We do limited pluging. If the bio can be merged, do that.
1299 * Otherwise the existing request in the plug list will be
1300 * issued. So the plug list will have one request at most
1301 */
1302 if (plug) {
1303 /*
1304 * The plug list might get flushed before this. If that
1305 * happens, same_queue_rq is invalid and plug list is
1306 * empty
1307 */
1308 if (same_queue_rq && !list_empty(&plug->mq_list)) {
1309 old_rq = same_queue_rq;
1310 list_del_init(&old_rq->queuelist);
1311 }
1312 list_add_tail(&rq->queuelist, &plug->mq_list);
1313 } else /* is_sync */
1314 old_rq = rq;
1315 blk_mq_put_ctx(data.ctx);
1316 if (!old_rq)
1317 goto done;
1318 if (!blk_mq_direct_issue_request(old_rq, &cookie))
1319 goto done;
1320 blk_mq_insert_request(old_rq, false, true, true);
1321 goto done;
1322 }
1323
1324 if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1325 /*
1326 * For a SYNC request, send it to the hardware immediately. For
1327 * an ASYNC request, just ensure that we run it later on. The
1328 * latter allows for merging opportunities and more efficient
1329 * dispatching.
1330 */
1331run_queue:
1332 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1333 }
1334 blk_mq_put_ctx(data.ctx);
1335done:
1336 return cookie;
1337}
1338
1339/*
1340 * Single hardware queue variant. This will attempt to use any per-process
1341 * plug for merging and IO deferral.
1342 */
1343static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
1344{
1345 const int is_sync = rw_is_sync(bio->bi_rw);
1346 const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
1347 struct blk_plug *plug;
1348 unsigned int request_count = 0;
1349 struct blk_map_ctx data;
1350 struct request *rq;
1351 blk_qc_t cookie;
1352
1353 blk_queue_bounce(q, &bio);
1354
1355 if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1356 bio_io_error(bio);
1357 return BLK_QC_T_NONE;
1358 }
1359
1360 blk_queue_split(q, &bio, q->bio_split);
1361
1362 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1363 blk_attempt_plug_merge(q, bio, &request_count, NULL))
1364 return BLK_QC_T_NONE;
1365
1366 rq = blk_mq_map_request(q, bio, &data);
1367 if (unlikely(!rq))
1368 return BLK_QC_T_NONE;
1369
1370 cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
1371
1372 if (unlikely(is_flush_fua)) {
1373 blk_mq_bio_to_request(rq, bio);
1374 blk_insert_flush(rq);
1375 goto run_queue;
1376 }
1377
1378 /*
1379 * A task plug currently exists. Since this is completely lockless,
1380 * utilize that to temporarily store requests until the task is
1381 * either done or scheduled away.
1382 */
1383 plug = current->plug;
1384 if (plug) {
1385 blk_mq_bio_to_request(rq, bio);
1386 if (!request_count)
1387 trace_block_plug(q);
1388
1389 blk_mq_put_ctx(data.ctx);
1390
1391 if (request_count >= BLK_MAX_REQUEST_COUNT) {
1392 blk_flush_plug_list(plug, false);
1393 trace_block_plug(q);
1394 }
1395
1396 list_add_tail(&rq->queuelist, &plug->mq_list);
1397 return cookie;
1398 }
1399
1400 if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1401 /*
1402 * For a SYNC request, send it to the hardware immediately. For
1403 * an ASYNC request, just ensure that we run it later on. The
1404 * latter allows for merging opportunities and more efficient
1405 * dispatching.
1406 */
1407run_queue:
1408 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1409 }
1410
1411 blk_mq_put_ctx(data.ctx);
1412 return cookie;
1413}
1414
1415/*
1416 * Default mapping to a software queue, since we use one per CPU.
1417 */
1418struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
1419{
1420 return q->queue_hw_ctx[q->mq_map[cpu]];
1421}
1422EXPORT_SYMBOL(blk_mq_map_queue);
1423
1424static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
1425 struct blk_mq_tags *tags, unsigned int hctx_idx)
1426{
1427 struct page *page;
1428
1429 if (tags->rqs && set->ops->exit_request) {
1430 int i;
1431
1432 for (i = 0; i < tags->nr_tags; i++) {
1433 if (!tags->rqs[i])
1434 continue;
1435 set->ops->exit_request(set->driver_data, tags->rqs[i],
1436 hctx_idx, i);
1437 tags->rqs[i] = NULL;
1438 }
1439 }
1440
1441 while (!list_empty(&tags->page_list)) {
1442 page = list_first_entry(&tags->page_list, struct page, lru);
1443 list_del_init(&page->lru);
1444 /*
1445 * Remove kmemleak object previously allocated in
1446 * blk_mq_init_rq_map().
1447 */
1448 kmemleak_free(page_address(page));
1449 __free_pages(page, page->private);
1450 }
1451
1452 kfree(tags->rqs);
1453
1454 blk_mq_free_tags(tags);
1455}
1456
1457static size_t order_to_size(unsigned int order)
1458{
1459 return (size_t)PAGE_SIZE << order;
1460}
1461
1462static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
1463 unsigned int hctx_idx)
1464{
1465 struct blk_mq_tags *tags;
1466 unsigned int i, j, entries_per_page, max_order = 4;
1467 size_t rq_size, left;
1468
1469 tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
1470 set->numa_node,
1471 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1472 if (!tags)
1473 return NULL;
1474
1475 INIT_LIST_HEAD(&tags->page_list);
1476
1477 tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
1478 GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
1479 set->numa_node);
1480 if (!tags->rqs) {
1481 blk_mq_free_tags(tags);
1482 return NULL;
1483 }
1484
1485 /*
1486 * rq_size is the size of the request plus driver payload, rounded
1487 * to the cacheline size
1488 */
1489 rq_size = round_up(sizeof(struct request) + set->cmd_size,
1490 cache_line_size());
1491 left = rq_size * set->queue_depth;
1492
1493 for (i = 0; i < set->queue_depth; ) {
1494 int this_order = max_order;
1495 struct page *page;
1496 int to_do;
1497 void *p;
1498
1499 while (left < order_to_size(this_order - 1) && this_order)
1500 this_order--;
1501
1502 do {
1503 page = alloc_pages_node(set->numa_node,
1504 GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1505 this_order);
1506 if (page)
1507 break;
1508 if (!this_order--)
1509 break;
1510 if (order_to_size(this_order) < rq_size)
1511 break;
1512 } while (1);
1513
1514 if (!page)
1515 goto fail;
1516
1517 page->private = this_order;
1518 list_add_tail(&page->lru, &tags->page_list);
1519
1520 p = page_address(page);
1521 /*
1522 * Allow kmemleak to scan these pages as they contain pointers
1523 * to additional allocations like via ops->init_request().
1524 */
1525 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_KERNEL);
1526 entries_per_page = order_to_size(this_order) / rq_size;
1527 to_do = min(entries_per_page, set->queue_depth - i);
1528 left -= to_do * rq_size;
1529 for (j = 0; j < to_do; j++) {
1530 tags->rqs[i] = p;
1531 if (set->ops->init_request) {
1532 if (set->ops->init_request(set->driver_data,
1533 tags->rqs[i], hctx_idx, i,
1534 set->numa_node)) {
1535 tags->rqs[i] = NULL;
1536 goto fail;
1537 }
1538 }
1539
1540 p += rq_size;
1541 i++;
1542 }
1543 }
1544 return tags;
1545
1546fail:
1547 blk_mq_free_rq_map(set, tags, hctx_idx);
1548 return NULL;
1549}
1550
1551static void blk_mq_free_bitmap(struct blk_mq_ctxmap *bitmap)
1552{
1553 kfree(bitmap->map);
1554}
1555
1556static int blk_mq_alloc_bitmap(struct blk_mq_ctxmap *bitmap, int node)
1557{
1558 unsigned int bpw = 8, total, num_maps, i;
1559
1560 bitmap->bits_per_word = bpw;
1561
1562 num_maps = ALIGN(nr_cpu_ids, bpw) / bpw;
1563 bitmap->map = kzalloc_node(num_maps * sizeof(struct blk_align_bitmap),
1564 GFP_KERNEL, node);
1565 if (!bitmap->map)
1566 return -ENOMEM;
1567
1568 total = nr_cpu_ids;
1569 for (i = 0; i < num_maps; i++) {
1570 bitmap->map[i].depth = min(total, bitmap->bits_per_word);
1571 total -= bitmap->map[i].depth;
1572 }
1573
1574 return 0;
1575}
1576
1577static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
1578{
1579 struct request_queue *q = hctx->queue;
1580 struct blk_mq_ctx *ctx;
1581 LIST_HEAD(tmp);
1582
1583 /*
1584 * Move ctx entries to new CPU, if this one is going away.
1585 */
1586 ctx = __blk_mq_get_ctx(q, cpu);
1587
1588 spin_lock(&ctx->lock);
1589 if (!list_empty(&ctx->rq_list)) {
1590 list_splice_init(&ctx->rq_list, &tmp);
1591 blk_mq_hctx_clear_pending(hctx, ctx);
1592 }
1593 spin_unlock(&ctx->lock);
1594
1595 if (list_empty(&tmp))
1596 return NOTIFY_OK;
1597
1598 ctx = blk_mq_get_ctx(q);
1599 spin_lock(&ctx->lock);
1600
1601 while (!list_empty(&tmp)) {
1602 struct request *rq;
1603
1604 rq = list_first_entry(&tmp, struct request, queuelist);
1605 rq->mq_ctx = ctx;
1606 list_move_tail(&rq->queuelist, &ctx->rq_list);
1607 }
1608
1609 hctx = q->mq_ops->map_queue(q, ctx->cpu);
1610 blk_mq_hctx_mark_pending(hctx, ctx);
1611
1612 spin_unlock(&ctx->lock);
1613
1614 blk_mq_run_hw_queue(hctx, true);
1615 blk_mq_put_ctx(ctx);
1616 return NOTIFY_OK;
1617}
1618
1619static int blk_mq_hctx_notify(void *data, unsigned long action,
1620 unsigned int cpu)
1621{
1622 struct blk_mq_hw_ctx *hctx = data;
1623
1624 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
1625 return blk_mq_hctx_cpu_offline(hctx, cpu);
1626
1627 /*
1628 * In case of CPU online, tags may be reallocated
1629 * in blk_mq_map_swqueue() after mapping is updated.
1630 */
1631
1632 return NOTIFY_OK;
1633}
1634
1635/* hctx->ctxs will be freed in queue's release handler */
1636static void blk_mq_exit_hctx(struct request_queue *q,
1637 struct blk_mq_tag_set *set,
1638 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1639{
1640 unsigned flush_start_tag = set->queue_depth;
1641
1642 blk_mq_tag_idle(hctx);
1643
1644 if (set->ops->exit_request)
1645 set->ops->exit_request(set->driver_data,
1646 hctx->fq->flush_rq, hctx_idx,
1647 flush_start_tag + hctx_idx);
1648
1649 if (set->ops->exit_hctx)
1650 set->ops->exit_hctx(hctx, hctx_idx);
1651
1652 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1653 blk_free_flush_queue(hctx->fq);
1654 blk_mq_free_bitmap(&hctx->ctx_map);
1655}
1656
1657static void blk_mq_exit_hw_queues(struct request_queue *q,
1658 struct blk_mq_tag_set *set, int nr_queue)
1659{
1660 struct blk_mq_hw_ctx *hctx;
1661 unsigned int i;
1662
1663 queue_for_each_hw_ctx(q, hctx, i) {
1664 if (i == nr_queue)
1665 break;
1666 blk_mq_exit_hctx(q, set, hctx, i);
1667 }
1668}
1669
1670static void blk_mq_free_hw_queues(struct request_queue *q,
1671 struct blk_mq_tag_set *set)
1672{
1673 struct blk_mq_hw_ctx *hctx;
1674 unsigned int i;
1675
1676 queue_for_each_hw_ctx(q, hctx, i)
1677 free_cpumask_var(hctx->cpumask);
1678}
1679
1680static int blk_mq_init_hctx(struct request_queue *q,
1681 struct blk_mq_tag_set *set,
1682 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1683{
1684 int node;
1685 unsigned flush_start_tag = set->queue_depth;
1686
1687 node = hctx->numa_node;
1688 if (node == NUMA_NO_NODE)
1689 node = hctx->numa_node = set->numa_node;
1690
1691 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
1692 INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1693 spin_lock_init(&hctx->lock);
1694 INIT_LIST_HEAD(&hctx->dispatch);
1695 hctx->queue = q;
1696 hctx->queue_num = hctx_idx;
1697 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1698
1699 blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
1700 blk_mq_hctx_notify, hctx);
1701 blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
1702
1703 hctx->tags = set->tags[hctx_idx];
1704
1705 /*
1706 * Allocate space for all possible cpus to avoid allocation at
1707 * runtime
1708 */
1709 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1710 GFP_KERNEL, node);
1711 if (!hctx->ctxs)
1712 goto unregister_cpu_notifier;
1713
1714 if (blk_mq_alloc_bitmap(&hctx->ctx_map, node))
1715 goto free_ctxs;
1716
1717 hctx->nr_ctx = 0;
1718
1719 if (set->ops->init_hctx &&
1720 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1721 goto free_bitmap;
1722
1723 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1724 if (!hctx->fq)
1725 goto exit_hctx;
1726
1727 if (set->ops->init_request &&
1728 set->ops->init_request(set->driver_data,
1729 hctx->fq->flush_rq, hctx_idx,
1730 flush_start_tag + hctx_idx, node))
1731 goto free_fq;
1732
1733 return 0;
1734
1735 free_fq:
1736 kfree(hctx->fq);
1737 exit_hctx:
1738 if (set->ops->exit_hctx)
1739 set->ops->exit_hctx(hctx, hctx_idx);
1740 free_bitmap:
1741 blk_mq_free_bitmap(&hctx->ctx_map);
1742 free_ctxs:
1743 kfree(hctx->ctxs);
1744 unregister_cpu_notifier:
1745 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1746
1747 return -1;
1748}
1749
1750static void blk_mq_init_cpu_queues(struct request_queue *q,
1751 unsigned int nr_hw_queues)
1752{
1753 unsigned int i;
1754
1755 for_each_possible_cpu(i) {
1756 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1757 struct blk_mq_hw_ctx *hctx;
1758
1759 memset(__ctx, 0, sizeof(*__ctx));
1760 __ctx->cpu = i;
1761 spin_lock_init(&__ctx->lock);
1762 INIT_LIST_HEAD(&__ctx->rq_list);
1763 __ctx->queue = q;
1764
1765 /* If the cpu isn't online, the cpu is mapped to first hctx */
1766 if (!cpu_online(i))
1767 continue;
1768
1769 hctx = q->mq_ops->map_queue(q, i);
1770
1771 /*
1772 * Set local node, IFF we have more than one hw queue. If
1773 * not, we remain on the home node of the device
1774 */
1775 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1776 hctx->numa_node = local_memory_node(cpu_to_node(i));
1777 }
1778}
1779
1780static void blk_mq_map_swqueue(struct request_queue *q,
1781 const struct cpumask *online_mask)
1782{
1783 unsigned int i;
1784 struct blk_mq_hw_ctx *hctx;
1785 struct blk_mq_ctx *ctx;
1786 struct blk_mq_tag_set *set = q->tag_set;
1787
1788 /*
1789 * Avoid others reading imcomplete hctx->cpumask through sysfs
1790 */
1791 mutex_lock(&q->sysfs_lock);
1792
1793 queue_for_each_hw_ctx(q, hctx, i) {
1794 cpumask_clear(hctx->cpumask);
1795 hctx->nr_ctx = 0;
1796 }
1797
1798 /*
1799 * Map software to hardware queues
1800 */
1801 for_each_possible_cpu(i) {
1802 /* If the cpu isn't online, the cpu is mapped to first hctx */
1803 if (!cpumask_test_cpu(i, online_mask))
1804 continue;
1805
1806 ctx = per_cpu_ptr(q->queue_ctx, i);
1807 hctx = q->mq_ops->map_queue(q, i);
1808
1809 cpumask_set_cpu(i, hctx->cpumask);
1810 ctx->index_hw = hctx->nr_ctx;
1811 hctx->ctxs[hctx->nr_ctx++] = ctx;
1812 }
1813
1814 mutex_unlock(&q->sysfs_lock);
1815
1816 queue_for_each_hw_ctx(q, hctx, i) {
1817 struct blk_mq_ctxmap *map = &hctx->ctx_map;
1818
1819 /*
1820 * If no software queues are mapped to this hardware queue,
1821 * disable it and free the request entries.
1822 */
1823 if (!hctx->nr_ctx) {
1824 if (set->tags[i]) {
1825 blk_mq_free_rq_map(set, set->tags[i], i);
1826 set->tags[i] = NULL;
1827 }
1828 hctx->tags = NULL;
1829 continue;
1830 }
1831
1832 /* unmapped hw queue can be remapped after CPU topo changed */
1833 if (!set->tags[i])
1834 set->tags[i] = blk_mq_init_rq_map(set, i);
1835 hctx->tags = set->tags[i];
1836 WARN_ON(!hctx->tags);
1837
1838 cpumask_copy(hctx->tags->cpumask, hctx->cpumask);
1839 /*
1840 * Set the map size to the number of mapped software queues.
1841 * This is more accurate and more efficient than looping
1842 * over all possibly mapped software queues.
1843 */
1844 map->size = DIV_ROUND_UP(hctx->nr_ctx, map->bits_per_word);
1845
1846 /*
1847 * Initialize batch roundrobin counts
1848 */
1849 hctx->next_cpu = cpumask_first(hctx->cpumask);
1850 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1851 }
1852}
1853
1854static void queue_set_hctx_shared(struct request_queue *q, bool shared)
1855{
1856 struct blk_mq_hw_ctx *hctx;
1857 int i;
1858
1859 queue_for_each_hw_ctx(q, hctx, i) {
1860 if (shared)
1861 hctx->flags |= BLK_MQ_F_TAG_SHARED;
1862 else
1863 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
1864 }
1865}
1866
1867static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
1868{
1869 struct request_queue *q;
1870
1871 list_for_each_entry(q, &set->tag_list, tag_set_list) {
1872 blk_mq_freeze_queue(q);
1873 queue_set_hctx_shared(q, shared);
1874 blk_mq_unfreeze_queue(q);
1875 }
1876}
1877
1878static void blk_mq_del_queue_tag_set(struct request_queue *q)
1879{
1880 struct blk_mq_tag_set *set = q->tag_set;
1881
1882 mutex_lock(&set->tag_list_lock);
1883 list_del_init(&q->tag_set_list);
1884 if (list_is_singular(&set->tag_list)) {
1885 /* just transitioned to unshared */
1886 set->flags &= ~BLK_MQ_F_TAG_SHARED;
1887 /* update existing queue */
1888 blk_mq_update_tag_set_depth(set, false);
1889 }
1890 mutex_unlock(&set->tag_list_lock);
1891}
1892
1893static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
1894 struct request_queue *q)
1895{
1896 q->tag_set = set;
1897
1898 mutex_lock(&set->tag_list_lock);
1899
1900 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
1901 if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
1902 set->flags |= BLK_MQ_F_TAG_SHARED;
1903 /* update existing queue */
1904 blk_mq_update_tag_set_depth(set, true);
1905 }
1906 if (set->flags & BLK_MQ_F_TAG_SHARED)
1907 queue_set_hctx_shared(q, true);
1908 list_add_tail(&q->tag_set_list, &set->tag_list);
1909
1910 mutex_unlock(&set->tag_list_lock);
1911}
1912
1913/*
1914 * It is the actual release handler for mq, but we do it from
1915 * request queue's release handler for avoiding use-after-free
1916 * and headache because q->mq_kobj shouldn't have been introduced,
1917 * but we can't group ctx/kctx kobj without it.
1918 */
1919void blk_mq_release(struct request_queue *q)
1920{
1921 struct blk_mq_hw_ctx *hctx;
1922 unsigned int i;
1923
1924 /* hctx kobj stays in hctx */
1925 queue_for_each_hw_ctx(q, hctx, i) {
1926 if (!hctx)
1927 continue;
1928 kfree(hctx->ctxs);
1929 kfree(hctx);
1930 }
1931
1932 kfree(q->mq_map);
1933 q->mq_map = NULL;
1934
1935 kfree(q->queue_hw_ctx);
1936
1937 /* ctx kobj stays in queue_ctx */
1938 free_percpu(q->queue_ctx);
1939}
1940
1941struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
1942{
1943 struct request_queue *uninit_q, *q;
1944
1945 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
1946 if (!uninit_q)
1947 return ERR_PTR(-ENOMEM);
1948
1949 q = blk_mq_init_allocated_queue(set, uninit_q);
1950 if (IS_ERR(q))
1951 blk_cleanup_queue(uninit_q);
1952
1953 return q;
1954}
1955EXPORT_SYMBOL(blk_mq_init_queue);
1956
1957static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
1958 struct request_queue *q)
1959{
1960 int i, j;
1961 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
1962
1963 blk_mq_sysfs_unregister(q);
1964 for (i = 0; i < set->nr_hw_queues; i++) {
1965 int node;
1966
1967 if (hctxs[i])
1968 continue;
1969
1970 node = blk_mq_hw_queue_to_node(q->mq_map, i);
1971 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
1972 GFP_KERNEL, node);
1973 if (!hctxs[i])
1974 break;
1975
1976 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
1977 node)) {
1978 kfree(hctxs[i]);
1979 hctxs[i] = NULL;
1980 break;
1981 }
1982
1983 atomic_set(&hctxs[i]->nr_active, 0);
1984 hctxs[i]->numa_node = node;
1985 hctxs[i]->queue_num = i;
1986
1987 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
1988 free_cpumask_var(hctxs[i]->cpumask);
1989 kfree(hctxs[i]);
1990 hctxs[i] = NULL;
1991 break;
1992 }
1993 blk_mq_hctx_kobj_init(hctxs[i]);
1994 }
1995 for (j = i; j < q->nr_hw_queues; j++) {
1996 struct blk_mq_hw_ctx *hctx = hctxs[j];
1997
1998 if (hctx) {
1999 if (hctx->tags) {
2000 blk_mq_free_rq_map(set, hctx->tags, j);
2001 set->tags[j] = NULL;
2002 }
2003 blk_mq_exit_hctx(q, set, hctx, j);
2004 free_cpumask_var(hctx->cpumask);
2005 kobject_put(&hctx->kobj);
2006 kfree(hctx->ctxs);
2007 kfree(hctx);
2008 hctxs[j] = NULL;
2009
2010 }
2011 }
2012 q->nr_hw_queues = i;
2013 blk_mq_sysfs_register(q);
2014}
2015
2016struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2017 struct request_queue *q)
2018{
2019 /* mark the queue as mq asap */
2020 q->mq_ops = set->ops;
2021
2022 q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2023 if (!q->queue_ctx)
2024 return ERR_PTR(-ENOMEM);
2025
2026 q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2027 GFP_KERNEL, set->numa_node);
2028 if (!q->queue_hw_ctx)
2029 goto err_percpu;
2030
2031 q->mq_map = blk_mq_make_queue_map(set);
2032 if (!q->mq_map)
2033 goto err_map;
2034
2035 blk_mq_realloc_hw_ctxs(set, q);
2036 if (!q->nr_hw_queues)
2037 goto err_hctxs;
2038
2039 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2040 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2041
2042 q->nr_queues = nr_cpu_ids;
2043
2044 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2045
2046 if (!(set->flags & BLK_MQ_F_SG_MERGE))
2047 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2048
2049 q->sg_reserved_size = INT_MAX;
2050
2051 INIT_WORK(&q->requeue_work, blk_mq_requeue_work);
2052 INIT_LIST_HEAD(&q->requeue_list);
2053 spin_lock_init(&q->requeue_lock);
2054
2055 if (q->nr_hw_queues > 1)
2056 blk_queue_make_request(q, blk_mq_make_request);
2057 else
2058 blk_queue_make_request(q, blk_sq_make_request);
2059
2060 /*
2061 * Do this after blk_queue_make_request() overrides it...
2062 */
2063 q->nr_requests = set->queue_depth;
2064
2065 if (set->ops->complete)
2066 blk_queue_softirq_done(q, set->ops->complete);
2067
2068 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2069
2070 get_online_cpus();
2071 mutex_lock(&all_q_mutex);
2072
2073 list_add_tail(&q->all_q_node, &all_q_list);
2074 blk_mq_add_queue_tag_set(set, q);
2075 blk_mq_map_swqueue(q, cpu_online_mask);
2076
2077 mutex_unlock(&all_q_mutex);
2078 put_online_cpus();
2079
2080 return q;
2081
2082err_hctxs:
2083 kfree(q->mq_map);
2084err_map:
2085 kfree(q->queue_hw_ctx);
2086err_percpu:
2087 free_percpu(q->queue_ctx);
2088 return ERR_PTR(-ENOMEM);
2089}
2090EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2091
2092void blk_mq_free_queue(struct request_queue *q)
2093{
2094 struct blk_mq_tag_set *set = q->tag_set;
2095
2096 mutex_lock(&all_q_mutex);
2097 list_del_init(&q->all_q_node);
2098 mutex_unlock(&all_q_mutex);
2099
2100 blk_mq_del_queue_tag_set(q);
2101
2102 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2103 blk_mq_free_hw_queues(q, set);
2104}
2105
2106/* Basically redo blk_mq_init_queue with queue frozen */
2107static void blk_mq_queue_reinit(struct request_queue *q,
2108 const struct cpumask *online_mask)
2109{
2110 WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2111
2112 blk_mq_sysfs_unregister(q);
2113
2114 blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues, online_mask);
2115
2116 /*
2117 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2118 * we should change hctx numa_node according to new topology (this
2119 * involves free and re-allocate memory, worthy doing?)
2120 */
2121
2122 blk_mq_map_swqueue(q, online_mask);
2123
2124 blk_mq_sysfs_register(q);
2125}
2126
2127static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
2128 unsigned long action, void *hcpu)
2129{
2130 struct request_queue *q;
2131 int cpu = (unsigned long)hcpu;
2132 /*
2133 * New online cpumask which is going to be set in this hotplug event.
2134 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2135 * one-by-one and dynamically allocating this could result in a failure.
2136 */
2137 static struct cpumask online_new;
2138
2139 /*
2140 * Before hotadded cpu starts handling requests, new mappings must
2141 * be established. Otherwise, these requests in hw queue might
2142 * never be dispatched.
2143 *
2144 * For example, there is a single hw queue (hctx) and two CPU queues
2145 * (ctx0 for CPU0, and ctx1 for CPU1).
2146 *
2147 * Now CPU1 is just onlined and a request is inserted into
2148 * ctx1->rq_list and set bit0 in pending bitmap as ctx1->index_hw is
2149 * still zero.
2150 *
2151 * And then while running hw queue, flush_busy_ctxs() finds bit0 is
2152 * set in pending bitmap and tries to retrieve requests in
2153 * hctx->ctxs[0]->rq_list. But htx->ctxs[0] is a pointer to ctx0,
2154 * so the request in ctx1->rq_list is ignored.
2155 */
2156 switch (action & ~CPU_TASKS_FROZEN) {
2157 case CPU_DEAD:
2158 case CPU_UP_CANCELED:
2159 cpumask_copy(&online_new, cpu_online_mask);
2160 break;
2161 case CPU_UP_PREPARE:
2162 cpumask_copy(&online_new, cpu_online_mask);
2163 cpumask_set_cpu(cpu, &online_new);
2164 break;
2165 default:
2166 return NOTIFY_OK;
2167 }
2168
2169 mutex_lock(&all_q_mutex);
2170
2171 /*
2172 * We need to freeze and reinit all existing queues. Freezing
2173 * involves synchronous wait for an RCU grace period and doing it
2174 * one by one may take a long time. Start freezing all queues in
2175 * one swoop and then wait for the completions so that freezing can
2176 * take place in parallel.
2177 */
2178 list_for_each_entry(q, &all_q_list, all_q_node)
2179 blk_mq_freeze_queue_start(q);
2180 list_for_each_entry(q, &all_q_list, all_q_node) {
2181 blk_mq_freeze_queue_wait(q);
2182
2183 /*
2184 * timeout handler can't touch hw queue during the
2185 * reinitialization
2186 */
2187 del_timer_sync(&q->timeout);
2188 }
2189
2190 list_for_each_entry(q, &all_q_list, all_q_node)
2191 blk_mq_queue_reinit(q, &online_new);
2192
2193 list_for_each_entry(q, &all_q_list, all_q_node)
2194 blk_mq_unfreeze_queue(q);
2195
2196 mutex_unlock(&all_q_mutex);
2197 return NOTIFY_OK;
2198}
2199
2200static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2201{
2202 int i;
2203
2204 for (i = 0; i < set->nr_hw_queues; i++) {
2205 set->tags[i] = blk_mq_init_rq_map(set, i);
2206 if (!set->tags[i])
2207 goto out_unwind;
2208 }
2209
2210 return 0;
2211
2212out_unwind:
2213 while (--i >= 0)
2214 blk_mq_free_rq_map(set, set->tags[i], i);
2215
2216 return -ENOMEM;
2217}
2218
2219/*
2220 * Allocate the request maps associated with this tag_set. Note that this
2221 * may reduce the depth asked for, if memory is tight. set->queue_depth
2222 * will be updated to reflect the allocated depth.
2223 */
2224static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2225{
2226 unsigned int depth;
2227 int err;
2228
2229 depth = set->queue_depth;
2230 do {
2231 err = __blk_mq_alloc_rq_maps(set);
2232 if (!err)
2233 break;
2234
2235 set->queue_depth >>= 1;
2236 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2237 err = -ENOMEM;
2238 break;
2239 }
2240 } while (set->queue_depth);
2241
2242 if (!set->queue_depth || err) {
2243 pr_err("blk-mq: failed to allocate request map\n");
2244 return -ENOMEM;
2245 }
2246
2247 if (depth != set->queue_depth)
2248 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2249 depth, set->queue_depth);
2250
2251 return 0;
2252}
2253
2254struct cpumask *blk_mq_tags_cpumask(struct blk_mq_tags *tags)
2255{
2256 return tags->cpumask;
2257}
2258EXPORT_SYMBOL_GPL(blk_mq_tags_cpumask);
2259
2260/*
2261 * Alloc a tag set to be associated with one or more request queues.
2262 * May fail with EINVAL for various error conditions. May adjust the
2263 * requested depth down, if if it too large. In that case, the set
2264 * value will be stored in set->queue_depth.
2265 */
2266int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2267{
2268 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2269
2270 if (!set->nr_hw_queues)
2271 return -EINVAL;
2272 if (!set->queue_depth)
2273 return -EINVAL;
2274 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2275 return -EINVAL;
2276
2277 if (!set->ops->queue_rq || !set->ops->map_queue)
2278 return -EINVAL;
2279
2280 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2281 pr_info("blk-mq: reduced tag depth to %u\n",
2282 BLK_MQ_MAX_DEPTH);
2283 set->queue_depth = BLK_MQ_MAX_DEPTH;
2284 }
2285
2286 /*
2287 * If a crashdump is active, then we are potentially in a very
2288 * memory constrained environment. Limit us to 1 queue and
2289 * 64 tags to prevent using too much memory.
2290 */
2291 if (is_kdump_kernel()) {
2292 set->nr_hw_queues = 1;
2293 set->queue_depth = min(64U, set->queue_depth);
2294 }
2295 /*
2296 * There is no use for more h/w queues than cpus.
2297 */
2298 if (set->nr_hw_queues > nr_cpu_ids)
2299 set->nr_hw_queues = nr_cpu_ids;
2300
2301 set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2302 GFP_KERNEL, set->numa_node);
2303 if (!set->tags)
2304 return -ENOMEM;
2305
2306 if (blk_mq_alloc_rq_maps(set))
2307 goto enomem;
2308
2309 mutex_init(&set->tag_list_lock);
2310 INIT_LIST_HEAD(&set->tag_list);
2311
2312 return 0;
2313enomem:
2314 kfree(set->tags);
2315 set->tags = NULL;
2316 return -ENOMEM;
2317}
2318EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2319
2320void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2321{
2322 int i;
2323
2324 for (i = 0; i < nr_cpu_ids; i++) {
2325 if (set->tags[i])
2326 blk_mq_free_rq_map(set, set->tags[i], i);
2327 }
2328
2329 kfree(set->tags);
2330 set->tags = NULL;
2331}
2332EXPORT_SYMBOL(blk_mq_free_tag_set);
2333
2334int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2335{
2336 struct blk_mq_tag_set *set = q->tag_set;
2337 struct blk_mq_hw_ctx *hctx;
2338 int i, ret;
2339
2340 if (!set || nr > set->queue_depth)
2341 return -EINVAL;
2342
2343 ret = 0;
2344 queue_for_each_hw_ctx(q, hctx, i) {
2345 if (!hctx->tags)
2346 continue;
2347 ret = blk_mq_tag_update_depth(hctx->tags, nr);
2348 if (ret)
2349 break;
2350 }
2351
2352 if (!ret)
2353 q->nr_requests = nr;
2354
2355 return ret;
2356}
2357
2358void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2359{
2360 struct request_queue *q;
2361
2362 if (nr_hw_queues > nr_cpu_ids)
2363 nr_hw_queues = nr_cpu_ids;
2364 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2365 return;
2366
2367 list_for_each_entry(q, &set->tag_list, tag_set_list)
2368 blk_mq_freeze_queue(q);
2369
2370 set->nr_hw_queues = nr_hw_queues;
2371 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2372 blk_mq_realloc_hw_ctxs(set, q);
2373
2374 if (q->nr_hw_queues > 1)
2375 blk_queue_make_request(q, blk_mq_make_request);
2376 else
2377 blk_queue_make_request(q, blk_sq_make_request);
2378
2379 blk_mq_queue_reinit(q, cpu_online_mask);
2380 }
2381
2382 list_for_each_entry(q, &set->tag_list, tag_set_list)
2383 blk_mq_unfreeze_queue(q);
2384}
2385EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2386
2387void blk_mq_disable_hotplug(void)
2388{
2389 mutex_lock(&all_q_mutex);
2390}
2391
2392void blk_mq_enable_hotplug(void)
2393{
2394 mutex_unlock(&all_q_mutex);
2395}
2396
2397static int __init blk_mq_init(void)
2398{
2399 blk_mq_cpu_init();
2400
2401 hotcpu_notifier(blk_mq_queue_reinit_notify, 0);
2402
2403 return 0;
2404}
2405subsys_initcall(blk_mq_init);