blk-mq.c 51.5 KB
Newer Older
1 2 3 4 5 6
/*
 * Block multiqueue core code
 *
 * Copyright (C) 2013-2014 Jens Axboe
 * Copyright (C) 2013-2014 Christoph Hellwig
 */
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/smp.h>
#include <linux/llist.h>
#include <linux/list_sort.h>
#include <linux/cpu.h>
#include <linux/cache.h>
#include <linux/sched/sysctl.h>
#include <linux/delay.h>
23
#include <linux/crash_dump.h>
24 25 26 27 28 29 30 31 32 33 34 35

#include <trace/events/block.h>

#include <linux/blk-mq.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-tag.h"

static DEFINE_MUTEX(all_q_mutex);
static LIST_HEAD(all_q_list);

static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
36
static void blk_mq_run_queues(struct request_queue *q);
37 38 39 40 41 42 43 44

/*
 * Check if any of the ctx's have pending work in this hardware queue
 */
static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
{
	unsigned int i;

45 46
	for (i = 0; i < hctx->ctx_map.map_size; i++)
		if (hctx->ctx_map.map[i].word)
47 48 49 50 51
			return true;

	return false;
}

52 53 54 55 56 57 58 59 60
static inline struct blk_align_bitmap *get_bm(struct blk_mq_hw_ctx *hctx,
					      struct blk_mq_ctx *ctx)
{
	return &hctx->ctx_map.map[ctx->index_hw / hctx->ctx_map.bits_per_word];
}

#define CTX_TO_BIT(hctx, ctx)	\
	((ctx)->index_hw & ((hctx)->ctx_map.bits_per_word - 1))

61 62 63 64 65 66
/*
 * Mark this ctx as having pending work in this hardware queue
 */
static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
				     struct blk_mq_ctx *ctx)
{
67 68 69 70 71 72 73 74 75 76 77 78
	struct blk_align_bitmap *bm = get_bm(hctx, ctx);

	if (!test_bit(CTX_TO_BIT(hctx, ctx), &bm->word))
		set_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
}

static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
				      struct blk_mq_ctx *ctx)
{
	struct blk_align_bitmap *bm = get_bm(hctx, ctx);

	clear_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
79 80 81 82
}

static int blk_mq_queue_enter(struct request_queue *q)
{
83 84
	while (true) {
		int ret;
85

86 87
		if (percpu_ref_tryget_live(&q->mq_usage_counter))
			return 0;
88

89 90 91 92 93 94 95
		ret = wait_event_interruptible(q->mq_freeze_wq,
				!q->mq_freeze_depth || blk_queue_dying(q));
		if (blk_queue_dying(q))
			return -ENODEV;
		if (ret)
			return ret;
	}
96 97 98 99
}

static void blk_mq_queue_exit(struct request_queue *q)
{
100 101 102 103 104 105 106 107 108
	percpu_ref_put(&q->mq_usage_counter);
}

static void blk_mq_usage_counter_release(struct percpu_ref *ref)
{
	struct request_queue *q =
		container_of(ref, struct request_queue, mq_usage_counter);

	wake_up_all(&q->mq_freeze_wq);
109 110
}

111
void blk_mq_freeze_queue_start(struct request_queue *q)
112
{
113 114
	bool freeze;

115
	spin_lock_irq(q->queue_lock);
116
	freeze = !q->mq_freeze_depth++;
117 118
	spin_unlock_irq(q->queue_lock);

119
	if (freeze) {
120
		percpu_ref_kill(&q->mq_usage_counter);
121
		blk_mq_run_queues(q);
122
	}
123
}
124
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
125 126 127

static void blk_mq_freeze_queue_wait(struct request_queue *q)
{
128
	wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter));
129 130
}

131 132 133 134 135 136 137 138 139
/*
 * Guarantee no request is in use, so we can change any data structure of
 * the queue afterward.
 */
void blk_mq_freeze_queue(struct request_queue *q)
{
	blk_mq_freeze_queue_start(q);
	blk_mq_freeze_queue_wait(q);
}
140
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
141

142
void blk_mq_unfreeze_queue(struct request_queue *q)
143
{
144
	bool wake;
145 146

	spin_lock_irq(q->queue_lock);
147 148
	wake = !--q->mq_freeze_depth;
	WARN_ON_ONCE(q->mq_freeze_depth < 0);
149
	spin_unlock_irq(q->queue_lock);
150 151
	if (wake) {
		percpu_ref_reinit(&q->mq_usage_counter);
152
		wake_up_all(&q->mq_freeze_wq);
153
	}
154
}
155
EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
156

157 158 159 160 161 162 163 164
void blk_mq_wake_waiters(struct request_queue *q)
{
	struct blk_mq_hw_ctx *hctx;
	unsigned int i;

	queue_for_each_hw_ctx(q, hctx, i)
		if (blk_mq_hw_queue_mapped(hctx))
			blk_mq_tag_wakeup_all(hctx->tags, true);
165 166 167 168 169 170 171

	/*
	 * If we are called because the queue has now been marked as
	 * dying, we need to ensure that processes currently waiting on
	 * the queue are notified as well.
	 */
	wake_up_all(&q->mq_freeze_wq);
172 173
}

174 175 176 177 178 179
bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
{
	return blk_mq_has_free_tags(hctx->tags);
}
EXPORT_SYMBOL(blk_mq_can_queue);

180 181
static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
			       struct request *rq, unsigned int rw_flags)
182
{
183 184 185
	if (blk_queue_io_stat(q))
		rw_flags |= REQ_IO_STAT;

186 187 188
	INIT_LIST_HEAD(&rq->queuelist);
	/* csd/requeue_work/fifo_time is initialized before use */
	rq->q = q;
189
	rq->mq_ctx = ctx;
190
	rq->cmd_flags |= rw_flags;
191 192 193 194 195 196
	/* do not touch atomic flags, it needs atomic ops against the timer */
	rq->cpu = -1;
	INIT_HLIST_NODE(&rq->hash);
	RB_CLEAR_NODE(&rq->rb_node);
	rq->rq_disk = NULL;
	rq->part = NULL;
197
	rq->start_time = jiffies;
198 199
#ifdef CONFIG_BLK_CGROUP
	rq->rl = NULL;
200
	set_start_time_ns(rq);
201 202 203 204 205 206 207 208 209 210
	rq->io_start_time_ns = 0;
#endif
	rq->nr_phys_segments = 0;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
	rq->nr_integrity_segments = 0;
#endif
	rq->special = NULL;
	/* tag was already set */
	rq->errors = 0;

211 212
	rq->cmd = rq->__cmd;

213 214 215 216 217 218
	rq->extra_len = 0;
	rq->sense_len = 0;
	rq->resid_len = 0;
	rq->sense = NULL;

	INIT_LIST_HEAD(&rq->timeout_list);
219 220
	rq->timeout = 0;

221 222 223 224
	rq->end_io = NULL;
	rq->end_io_data = NULL;
	rq->next_rq = NULL;

225 226 227
	ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
}

228
static struct request *
229
__blk_mq_alloc_request(struct blk_mq_alloc_data *data, int rw)
230 231 232 233
{
	struct request *rq;
	unsigned int tag;

234
	tag = blk_mq_get_tag(data);
235
	if (tag != BLK_MQ_TAG_FAIL) {
236
		rq = data->hctx->tags->rqs[tag];
237

238
		if (blk_mq_tag_busy(data->hctx)) {
239
			rq->cmd_flags = REQ_MQ_INFLIGHT;
240
			atomic_inc(&data->hctx->nr_active);
241 242 243
		}

		rq->tag = tag;
244
		blk_mq_rq_ctx_init(data->q, data->ctx, rq, rw);
245 246 247 248 249 250
		return rq;
	}

	return NULL;
}

251 252
struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp,
		bool reserved)
253
{
254 255
	struct blk_mq_ctx *ctx;
	struct blk_mq_hw_ctx *hctx;
256
	struct request *rq;
257
	struct blk_mq_alloc_data alloc_data;
258
	int ret;
259

260 261 262
	ret = blk_mq_queue_enter(q);
	if (ret)
		return ERR_PTR(ret);
263

264 265
	ctx = blk_mq_get_ctx(q);
	hctx = q->mq_ops->map_queue(q, ctx->cpu);
266 267
	blk_mq_set_alloc_data(&alloc_data, q, gfp & ~__GFP_WAIT,
			reserved, ctx, hctx);
268

269
	rq = __blk_mq_alloc_request(&alloc_data, rw);
270 271 272 273 274 275
	if (!rq && (gfp & __GFP_WAIT)) {
		__blk_mq_run_hw_queue(hctx);
		blk_mq_put_ctx(ctx);

		ctx = blk_mq_get_ctx(q);
		hctx = q->mq_ops->map_queue(q, ctx->cpu);
276 277 278 279
		blk_mq_set_alloc_data(&alloc_data, q, gfp, reserved, ctx,
				hctx);
		rq =  __blk_mq_alloc_request(&alloc_data, rw);
		ctx = alloc_data.ctx;
280 281
	}
	blk_mq_put_ctx(ctx);
K
Keith Busch 已提交
282 283
	if (!rq) {
		blk_mq_queue_exit(q);
284
		return ERR_PTR(-EWOULDBLOCK);
K
Keith Busch 已提交
285
	}
286 287
	return rq;
}
288
EXPORT_SYMBOL(blk_mq_alloc_request);
289 290 291 292 293 294 295

static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
				  struct blk_mq_ctx *ctx, struct request *rq)
{
	const int tag = rq->tag;
	struct request_queue *q = rq->q;

296 297
	if (rq->cmd_flags & REQ_MQ_INFLIGHT)
		atomic_dec(&hctx->nr_active);
298
	rq->cmd_flags = 0;
299

300
	clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
301
	blk_mq_put_tag(hctx, tag, &ctx->last_tag);
302 303 304
	blk_mq_queue_exit(q);
}

305
void blk_mq_free_hctx_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
306 307 308 309 310
{
	struct blk_mq_ctx *ctx = rq->mq_ctx;

	ctx->rq_completed[rq_is_sync(rq)]++;
	__blk_mq_free_request(hctx, ctx, rq);
311 312 313 314 315 316 317 318 319 320 321

}
EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request);

void blk_mq_free_request(struct request *rq)
{
	struct blk_mq_hw_ctx *hctx;
	struct request_queue *q = rq->q;

	hctx = q->mq_ops->map_queue(q, rq->mq_ctx->cpu);
	blk_mq_free_hctx_request(hctx, rq);
322
}
J
Jens Axboe 已提交
323
EXPORT_SYMBOL_GPL(blk_mq_free_request);
324

325
inline void __blk_mq_end_request(struct request *rq, int error)
326
{
M
Ming Lei 已提交
327 328
	blk_account_io_done(rq);

C
Christoph Hellwig 已提交
329
	if (rq->end_io) {
330
		rq->end_io(rq, error);
C
Christoph Hellwig 已提交
331 332 333
	} else {
		if (unlikely(blk_bidi_rq(rq)))
			blk_mq_free_request(rq->next_rq);
334
		blk_mq_free_request(rq);
C
Christoph Hellwig 已提交
335
	}
336
}
337
EXPORT_SYMBOL(__blk_mq_end_request);
338

339
void blk_mq_end_request(struct request *rq, int error)
340 341 342
{
	if (blk_update_request(rq, error, blk_rq_bytes(rq)))
		BUG();
343
	__blk_mq_end_request(rq, error);
344
}
345
EXPORT_SYMBOL(blk_mq_end_request);
346

347
static void __blk_mq_complete_request_remote(void *data)
348
{
349
	struct request *rq = data;
350

351
	rq->q->softirq_done_fn(rq);
352 353
}

354
static void blk_mq_ipi_complete_request(struct request *rq)
355 356
{
	struct blk_mq_ctx *ctx = rq->mq_ctx;
C
Christoph Hellwig 已提交
357
	bool shared = false;
358 359
	int cpu;

C
Christoph Hellwig 已提交
360
	if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
361 362 363
		rq->q->softirq_done_fn(rq);
		return;
	}
364 365

	cpu = get_cpu();
C
Christoph Hellwig 已提交
366 367 368 369
	if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
		shared = cpus_share_cache(cpu, ctx->cpu);

	if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
370
		rq->csd.func = __blk_mq_complete_request_remote;
371 372
		rq->csd.info = rq;
		rq->csd.flags = 0;
373
		smp_call_function_single_async(ctx->cpu, &rq->csd);
374
	} else {
375
		rq->q->softirq_done_fn(rq);
376
	}
377 378
	put_cpu();
}
379

380 381 382 383 384
void __blk_mq_complete_request(struct request *rq)
{
	struct request_queue *q = rq->q;

	if (!q->softirq_done_fn)
385
		blk_mq_end_request(rq, rq->errors);
386 387 388 389
	else
		blk_mq_ipi_complete_request(rq);
}

390 391 392 393 394 395 396 397 398 399
/**
 * blk_mq_complete_request - end I/O on a request
 * @rq:		the request being processed
 *
 * Description:
 *	Ends all I/O on a request. It does not handle partial completions.
 *	The actual completion happens out-of-order, through a IPI handler.
 **/
void blk_mq_complete_request(struct request *rq)
{
400 401 402
	struct request_queue *q = rq->q;

	if (unlikely(blk_should_fake_timeout(q)))
403
		return;
404 405
	if (!blk_mark_rq_complete(rq))
		__blk_mq_complete_request(rq);
406 407
}
EXPORT_SYMBOL(blk_mq_complete_request);
408

409 410 411 412 413 414
int blk_mq_request_started(struct request *rq)
{
	return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
}
EXPORT_SYMBOL_GPL(blk_mq_request_started);

415
void blk_mq_start_request(struct request *rq)
416 417 418 419 420
{
	struct request_queue *q = rq->q;

	trace_block_rq_issue(q, rq);

C
Christoph Hellwig 已提交
421
	rq->resid_len = blk_rq_bytes(rq);
C
Christoph Hellwig 已提交
422 423
	if (unlikely(blk_bidi_rq(rq)))
		rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
C
Christoph Hellwig 已提交
424

425
	blk_add_timer(rq);
426

427 428 429 430 431 432
	/*
	 * Ensure that ->deadline is visible before set the started
	 * flag and clear the completed flag.
	 */
	smp_mb__before_atomic();

433 434 435 436 437 438
	/*
	 * Mark us as started and clear complete. Complete might have been
	 * set if requeue raced with timeout, which then marked it as
	 * complete. So be sure to clear complete again when we start
	 * the request, otherwise we'll ignore the completion event.
	 */
439 440 441 442
	if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
		set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
	if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
		clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
443 444 445 446 447 448 449 450 451

	if (q->dma_drain_size && blk_rq_bytes(rq)) {
		/*
		 * Make sure space for the drain appears.  We know we can do
		 * this because max_hw_segments has been adjusted to be one
		 * fewer than the device can handle.
		 */
		rq->nr_phys_segments++;
	}
452
}
453
EXPORT_SYMBOL(blk_mq_start_request);
454

455
static void __blk_mq_requeue_request(struct request *rq)
456 457 458 459
{
	struct request_queue *q = rq->q;

	trace_block_rq_requeue(q, rq);
460

461 462 463 464
	if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
		if (q->dma_drain_size && blk_rq_bytes(rq))
			rq->nr_phys_segments--;
	}
465 466
}

467 468 469 470 471
void blk_mq_requeue_request(struct request *rq)
{
	__blk_mq_requeue_request(rq);

	BUG_ON(blk_queued_rq(rq));
472
	blk_mq_add_to_requeue_list(rq, true);
473 474 475
}
EXPORT_SYMBOL(blk_mq_requeue_request);

476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502
static void blk_mq_requeue_work(struct work_struct *work)
{
	struct request_queue *q =
		container_of(work, struct request_queue, requeue_work);
	LIST_HEAD(rq_list);
	struct request *rq, *next;
	unsigned long flags;

	spin_lock_irqsave(&q->requeue_lock, flags);
	list_splice_init(&q->requeue_list, &rq_list);
	spin_unlock_irqrestore(&q->requeue_lock, flags);

	list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
		if (!(rq->cmd_flags & REQ_SOFTBARRIER))
			continue;

		rq->cmd_flags &= ~REQ_SOFTBARRIER;
		list_del_init(&rq->queuelist);
		blk_mq_insert_request(rq, true, false, false);
	}

	while (!list_empty(&rq_list)) {
		rq = list_entry(rq_list.next, struct request, queuelist);
		list_del_init(&rq->queuelist);
		blk_mq_insert_request(rq, false, false, false);
	}

503 504 505 506 507
	/*
	 * Use the start variant of queue running here, so that running
	 * the requeue work will kick stopped queues.
	 */
	blk_mq_start_hw_queues(q);
508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531
}

void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
{
	struct request_queue *q = rq->q;
	unsigned long flags;

	/*
	 * We abuse this flag that is otherwise used by the I/O scheduler to
	 * request head insertation from the workqueue.
	 */
	BUG_ON(rq->cmd_flags & REQ_SOFTBARRIER);

	spin_lock_irqsave(&q->requeue_lock, flags);
	if (at_head) {
		rq->cmd_flags |= REQ_SOFTBARRIER;
		list_add(&rq->queuelist, &q->requeue_list);
	} else {
		list_add_tail(&rq->queuelist, &q->requeue_list);
	}
	spin_unlock_irqrestore(&q->requeue_lock, flags);
}
EXPORT_SYMBOL(blk_mq_add_to_requeue_list);

532 533 534 535 536 537
void blk_mq_cancel_requeue_work(struct request_queue *q)
{
	cancel_work_sync(&q->requeue_work);
}
EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work);

538 539 540 541 542 543
void blk_mq_kick_requeue_list(struct request_queue *q)
{
	kblockd_schedule_work(&q->requeue_work);
}
EXPORT_SYMBOL(blk_mq_kick_requeue_list);

544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563
void blk_mq_abort_requeue_list(struct request_queue *q)
{
	unsigned long flags;
	LIST_HEAD(rq_list);

	spin_lock_irqsave(&q->requeue_lock, flags);
	list_splice_init(&q->requeue_list, &rq_list);
	spin_unlock_irqrestore(&q->requeue_lock, flags);

	while (!list_empty(&rq_list)) {
		struct request *rq;

		rq = list_first_entry(&rq_list, struct request, queuelist);
		list_del_init(&rq->queuelist);
		rq->errors = -EIO;
		blk_mq_end_request(rq, rq->errors);
	}
}
EXPORT_SYMBOL(blk_mq_abort_requeue_list);

564 565
static inline bool is_flush_request(struct request *rq,
		struct blk_flush_queue *fq, unsigned int tag)
566
{
567
	return ((rq->cmd_flags & REQ_FLUSH_SEQ) &&
568
			fq->flush_rq->tag == tag);
569 570 571 572 573
}

struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
{
	struct request *rq = tags->rqs[tag];
574 575
	/* mq_ctx of flush rq is always cloned from the corresponding req */
	struct blk_flush_queue *fq = blk_get_flush_queue(rq->q, rq->mq_ctx);
576

577
	if (!is_flush_request(rq, fq, tag))
578
		return rq;
579

580
	return fq->flush_rq;
581 582 583
}
EXPORT_SYMBOL(blk_mq_tag_to_rq);

584
struct blk_mq_timeout_data {
585 586
	unsigned long next;
	unsigned int next_set;
587 588
};

589
void blk_mq_rq_timed_out(struct request *req, bool reserved)
590
{
591 592
	struct blk_mq_ops *ops = req->q->mq_ops;
	enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
593 594 595 596 597 598 599 600 601 602

	/*
	 * We know that complete is set at this point. If STARTED isn't set
	 * anymore, then the request isn't active and the "timeout" should
	 * just be ignored. This can happen due to the bitflag ordering.
	 * Timeout first checks if STARTED is set, and if it is, assumes
	 * the request is active. But if we race with completion, then
	 * we both flags will get cleared. So check here again, and ignore
	 * a timeout event with a request that isn't active.
	 */
603 604
	if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
		return;
605

606
	if (ops->timeout)
607
		ret = ops->timeout(req, reserved);
608 609 610 611 612 613 614 615 616 617 618 619 620 621 622

	switch (ret) {
	case BLK_EH_HANDLED:
		__blk_mq_complete_request(req);
		break;
	case BLK_EH_RESET_TIMER:
		blk_add_timer(req);
		blk_clear_rq_complete(req);
		break;
	case BLK_EH_NOT_HANDLED:
		break;
	default:
		printk(KERN_ERR "block: bad eh return: %d\n", ret);
		break;
	}
623
}
624

625 626 627 628
static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
		struct request *rq, void *priv, bool reserved)
{
	struct blk_mq_timeout_data *data = priv;
629

630 631 632 633 634 635 636 637 638
	if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
		/*
		 * If a request wasn't started before the queue was
		 * marked dying, kill it here or it'll go unnoticed.
		 */
		if (unlikely(blk_queue_dying(rq->q))) {
			rq->errors = -EIO;
			blk_mq_complete_request(rq);
		}
639
		return;
640
	}
641 642
	if (rq->cmd_flags & REQ_NO_TIMEOUT)
		return;
643

644 645
	if (time_after_eq(jiffies, rq->deadline)) {
		if (!blk_mark_rq_complete(rq))
646
			blk_mq_rq_timed_out(rq, reserved);
647 648 649 650
	} else if (!data->next_set || time_after(data->next, rq->deadline)) {
		data->next = rq->deadline;
		data->next_set = 1;
	}
651 652
}

653
static void blk_mq_rq_timer(unsigned long priv)
654
{
655 656 657 658 659
	struct request_queue *q = (struct request_queue *)priv;
	struct blk_mq_timeout_data data = {
		.next		= 0,
		.next_set	= 0,
	};
660
	struct blk_mq_hw_ctx *hctx;
661
	int i;
662

663 664 665 666 667
	queue_for_each_hw_ctx(q, hctx, i) {
		/*
		 * If not software queues are currently mapped to this
		 * hardware queue, there's nothing to check
		 */
668
		if (!blk_mq_hw_queue_mapped(hctx))
669 670
			continue;

671
		blk_mq_tag_busy_iter(hctx, blk_mq_check_expired, &data);
672
	}
673

674 675 676
	if (data.next_set) {
		data.next = blk_rq_timeout(round_jiffies_up(data.next));
		mod_timer(&q->timeout, data.next);
677 678 679 680
	} else {
		queue_for_each_hw_ctx(q, hctx, i)
			blk_mq_tag_idle(hctx);
	}
681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721
}

/*
 * Reverse check our software queue for entries that we could potentially
 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
 * too much time checking for merges.
 */
static bool blk_mq_attempt_merge(struct request_queue *q,
				 struct blk_mq_ctx *ctx, struct bio *bio)
{
	struct request *rq;
	int checked = 8;

	list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
		int el_ret;

		if (!checked--)
			break;

		if (!blk_rq_merge_ok(rq, bio))
			continue;

		el_ret = blk_try_merge(rq, bio);
		if (el_ret == ELEVATOR_BACK_MERGE) {
			if (bio_attempt_back_merge(q, rq, bio)) {
				ctx->rq_merged++;
				return true;
			}
			break;
		} else if (el_ret == ELEVATOR_FRONT_MERGE) {
			if (bio_attempt_front_merge(q, rq, bio)) {
				ctx->rq_merged++;
				return true;
			}
			break;
		}
	}

	return false;
}

722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755
/*
 * Process software queues that have been marked busy, splicing them
 * to the for-dispatch
 */
static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
{
	struct blk_mq_ctx *ctx;
	int i;

	for (i = 0; i < hctx->ctx_map.map_size; i++) {
		struct blk_align_bitmap *bm = &hctx->ctx_map.map[i];
		unsigned int off, bit;

		if (!bm->word)
			continue;

		bit = 0;
		off = i * hctx->ctx_map.bits_per_word;
		do {
			bit = find_next_bit(&bm->word, bm->depth, bit);
			if (bit >= bm->depth)
				break;

			ctx = hctx->ctxs[bit + off];
			clear_bit(bit, &bm->word);
			spin_lock(&ctx->lock);
			list_splice_tail_init(&ctx->rq_list, list);
			spin_unlock(&ctx->lock);

			bit++;
		} while (1);
	}
}

756 757 758 759 760 761 762 763 764 765 766
/*
 * Run this hardware queue, pulling any software queues mapped to it in.
 * Note that this function currently has various problems around ordering
 * of IO. In particular, we'd like FIFO behaviour on handling existing
 * items on the hctx->dispatch list. Ignore that for now.
 */
static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
{
	struct request_queue *q = hctx->queue;
	struct request *rq;
	LIST_HEAD(rq_list);
767 768
	LIST_HEAD(driver_list);
	struct list_head *dptr;
769
	int queued;
770

771
	WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask));
772

773
	if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
774 775 776 777 778 779 780
		return;

	hctx->run++;

	/*
	 * Touch any software queue that has pending entries.
	 */
781
	flush_busy_ctxs(hctx, &rq_list);
782 783 784 785 786 787 788 789 790 791 792 793

	/*
	 * If we have previous entries on our dispatch list, grab them
	 * and stuff them at the front for more fair dispatch.
	 */
	if (!list_empty_careful(&hctx->dispatch)) {
		spin_lock(&hctx->lock);
		if (!list_empty(&hctx->dispatch))
			list_splice_init(&hctx->dispatch, &rq_list);
		spin_unlock(&hctx->lock);
	}

794 795 796 797 798 799
	/*
	 * Start off with dptr being NULL, so we start the first request
	 * immediately, even if we have more pending.
	 */
	dptr = NULL;

800 801 802
	/*
	 * Now process all the entries, sending them to the driver.
	 */
803
	queued = 0;
804
	while (!list_empty(&rq_list)) {
805
		struct blk_mq_queue_data bd;
806 807 808 809 810
		int ret;

		rq = list_first_entry(&rq_list, struct request, queuelist);
		list_del_init(&rq->queuelist);

811 812 813 814 815
		bd.rq = rq;
		bd.list = dptr;
		bd.last = list_empty(&rq_list);

		ret = q->mq_ops->queue_rq(hctx, &bd);
816 817 818 819 820 821
		switch (ret) {
		case BLK_MQ_RQ_QUEUE_OK:
			queued++;
			continue;
		case BLK_MQ_RQ_QUEUE_BUSY:
			list_add(&rq->queuelist, &rq_list);
822
			__blk_mq_requeue_request(rq);
823 824 825 826
			break;
		default:
			pr_err("blk-mq: bad return on queue: %d\n", ret);
		case BLK_MQ_RQ_QUEUE_ERROR:
827
			rq->errors = -EIO;
828
			blk_mq_end_request(rq, rq->errors);
829 830 831 832 833
			break;
		}

		if (ret == BLK_MQ_RQ_QUEUE_BUSY)
			break;
834 835 836 837 838 839 840

		/*
		 * We've done the first request. If we have more than 1
		 * left in the list, set dptr to defer issue.
		 */
		if (!dptr && rq_list.next != rq_list.prev)
			dptr = &driver_list;
841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858
	}

	if (!queued)
		hctx->dispatched[0]++;
	else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
		hctx->dispatched[ilog2(queued) + 1]++;

	/*
	 * Any items that need requeuing? Stuff them into hctx->dispatch,
	 * that is where we will continue on next queue run.
	 */
	if (!list_empty(&rq_list)) {
		spin_lock(&hctx->lock);
		list_splice(&rq_list, &hctx->dispatch);
		spin_unlock(&hctx->lock);
	}
}

859 860 861 862 863 864 865 866
/*
 * It'd be great if the workqueue API had a way to pass
 * in a mask and had some smarts for more clever placement.
 * For now we just round-robin here, switching for every
 * BLK_MQ_CPU_WORK_BATCH queued items.
 */
static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
{
867 868
	if (hctx->queue->nr_hw_queues == 1)
		return WORK_CPU_UNBOUND;
869 870

	if (--hctx->next_cpu_batch <= 0) {
871
		int cpu = hctx->next_cpu, next_cpu;
872 873 874 875 876 877 878

		next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
		if (next_cpu >= nr_cpu_ids)
			next_cpu = cpumask_first(hctx->cpumask);

		hctx->next_cpu = next_cpu;
		hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
879 880

		return cpu;
881 882
	}

883
	return hctx->next_cpu;
884 885
}

886 887
void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
{
888 889
	if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state) ||
	    !blk_mq_hw_queue_mapped(hctx)))
890 891
		return;

892
	if (!async) {
893 894
		int cpu = get_cpu();
		if (cpumask_test_cpu(cpu, hctx->cpumask)) {
895
			__blk_mq_run_hw_queue(hctx);
896
			put_cpu();
897 898
			return;
		}
899

900
		put_cpu();
901
	}
902

903 904
	kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
			&hctx->run_work, 0);
905 906
}

907
static void blk_mq_run_queues(struct request_queue *q)
908 909 910 911 912 913 914
{
	struct blk_mq_hw_ctx *hctx;
	int i;

	queue_for_each_hw_ctx(q, hctx, i) {
		if ((!blk_mq_hctx_has_pending(hctx) &&
		    list_empty_careful(&hctx->dispatch)) ||
915
		    test_bit(BLK_MQ_S_STOPPED, &hctx->state))
916 917
			continue;

918
		blk_mq_run_hw_queue(hctx, false);
919 920 921 922 923
	}
}

void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
924 925
	cancel_delayed_work(&hctx->run_work);
	cancel_delayed_work(&hctx->delay_work);
926 927 928 929
	set_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queue);

930 931 932 933 934 935 936 937 938 939
void blk_mq_stop_hw_queues(struct request_queue *q)
{
	struct blk_mq_hw_ctx *hctx;
	int i;

	queue_for_each_hw_ctx(q, hctx, i)
		blk_mq_stop_hw_queue(hctx);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queues);

940 941 942
void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
{
	clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
943

944
	blk_mq_run_hw_queue(hctx, false);
945 946 947
}
EXPORT_SYMBOL(blk_mq_start_hw_queue);

948 949 950 951 952 953 954 955 956 957
void blk_mq_start_hw_queues(struct request_queue *q)
{
	struct blk_mq_hw_ctx *hctx;
	int i;

	queue_for_each_hw_ctx(q, hctx, i)
		blk_mq_start_hw_queue(hctx);
}
EXPORT_SYMBOL(blk_mq_start_hw_queues);

958
void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
959 960 961 962 963 964 965 966 967
{
	struct blk_mq_hw_ctx *hctx;
	int i;

	queue_for_each_hw_ctx(q, hctx, i) {
		if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
			continue;

		clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
968
		blk_mq_run_hw_queue(hctx, async);
969 970 971 972
	}
}
EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);

973
static void blk_mq_run_work_fn(struct work_struct *work)
974 975 976
{
	struct blk_mq_hw_ctx *hctx;

977
	hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
978

979 980 981
	__blk_mq_run_hw_queue(hctx);
}

982 983 984 985 986 987 988 989 990 991 992 993
static void blk_mq_delay_work_fn(struct work_struct *work)
{
	struct blk_mq_hw_ctx *hctx;

	hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);

	if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
		__blk_mq_run_hw_queue(hctx);
}

void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
{
994 995
	if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
		return;
996

997 998
	kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
			&hctx->delay_work, msecs_to_jiffies(msecs));
999 1000 1001
}
EXPORT_SYMBOL(blk_mq_delay_queue);

1002
static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
1003
				    struct request *rq, bool at_head)
1004 1005 1006
{
	struct blk_mq_ctx *ctx = rq->mq_ctx;

1007 1008
	trace_block_rq_insert(hctx->queue, rq);

1009 1010 1011 1012
	if (at_head)
		list_add(&rq->queuelist, &ctx->rq_list);
	else
		list_add_tail(&rq->queuelist, &ctx->rq_list);
1013

1014 1015 1016
	blk_mq_hctx_mark_pending(hctx, ctx);
}

1017 1018
void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
		bool async)
1019
{
1020
	struct request_queue *q = rq->q;
1021
	struct blk_mq_hw_ctx *hctx;
1022 1023 1024 1025 1026
	struct blk_mq_ctx *ctx = rq->mq_ctx, *current_ctx;

	current_ctx = blk_mq_get_ctx(q);
	if (!cpu_online(ctx->cpu))
		rq->mq_ctx = ctx = current_ctx;
1027 1028 1029

	hctx = q->mq_ops->map_queue(q, ctx->cpu);

1030 1031 1032
	spin_lock(&ctx->lock);
	__blk_mq_insert_request(hctx, rq, at_head);
	spin_unlock(&ctx->lock);
1033 1034 1035

	if (run_queue)
		blk_mq_run_hw_queue(hctx, async);
1036 1037

	blk_mq_put_ctx(current_ctx);
1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068
}

static void blk_mq_insert_requests(struct request_queue *q,
				     struct blk_mq_ctx *ctx,
				     struct list_head *list,
				     int depth,
				     bool from_schedule)

{
	struct blk_mq_hw_ctx *hctx;
	struct blk_mq_ctx *current_ctx;

	trace_block_unplug(q, depth, !from_schedule);

	current_ctx = blk_mq_get_ctx(q);

	if (!cpu_online(ctx->cpu))
		ctx = current_ctx;
	hctx = q->mq_ops->map_queue(q, ctx->cpu);

	/*
	 * preemption doesn't flush plug list, so it's possible ctx->cpu is
	 * offline now
	 */
	spin_lock(&ctx->lock);
	while (!list_empty(list)) {
		struct request *rq;

		rq = list_first_entry(list, struct request, queuelist);
		list_del_init(&rq->queuelist);
		rq->mq_ctx = ctx;
1069
		__blk_mq_insert_request(hctx, rq, false);
1070 1071 1072 1073
	}
	spin_unlock(&ctx->lock);

	blk_mq_run_hw_queue(hctx, from_schedule);
1074
	blk_mq_put_ctx(current_ctx);
1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136
}

static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
{
	struct request *rqa = container_of(a, struct request, queuelist);
	struct request *rqb = container_of(b, struct request, queuelist);

	return !(rqa->mq_ctx < rqb->mq_ctx ||
		 (rqa->mq_ctx == rqb->mq_ctx &&
		  blk_rq_pos(rqa) < blk_rq_pos(rqb)));
}

void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
	struct blk_mq_ctx *this_ctx;
	struct request_queue *this_q;
	struct request *rq;
	LIST_HEAD(list);
	LIST_HEAD(ctx_list);
	unsigned int depth;

	list_splice_init(&plug->mq_list, &list);

	list_sort(NULL, &list, plug_ctx_cmp);

	this_q = NULL;
	this_ctx = NULL;
	depth = 0;

	while (!list_empty(&list)) {
		rq = list_entry_rq(list.next);
		list_del_init(&rq->queuelist);
		BUG_ON(!rq->q);
		if (rq->mq_ctx != this_ctx) {
			if (this_ctx) {
				blk_mq_insert_requests(this_q, this_ctx,
							&ctx_list, depth,
							from_schedule);
			}

			this_ctx = rq->mq_ctx;
			this_q = rq->q;
			depth = 0;
		}

		depth++;
		list_add_tail(&rq->queuelist, &ctx_list);
	}

	/*
	 * If 'this_ctx' is set, we know we have entries to complete
	 * on 'ctx_list'. Do those.
	 */
	if (this_ctx) {
		blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
				       from_schedule);
	}
}

static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
{
	init_request_from_bio(rq, bio);
1137

1138
	if (blk_do_io_stat(rq))
1139
		blk_account_io_start(rq, 1);
1140 1141
}

1142 1143 1144 1145 1146 1147
static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
{
	return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
		!blk_queue_nomerges(hctx->queue);
}

1148 1149 1150
static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
					 struct blk_mq_ctx *ctx,
					 struct request *rq, struct bio *bio)
1151
{
1152
	if (!hctx_allow_merges(hctx)) {
1153 1154 1155 1156 1157 1158 1159
		blk_mq_bio_to_request(rq, bio);
		spin_lock(&ctx->lock);
insert_rq:
		__blk_mq_insert_request(hctx, rq, false);
		spin_unlock(&ctx->lock);
		return false;
	} else {
1160 1161
		struct request_queue *q = hctx->queue;

1162 1163 1164 1165 1166
		spin_lock(&ctx->lock);
		if (!blk_mq_attempt_merge(q, ctx, bio)) {
			blk_mq_bio_to_request(rq, bio);
			goto insert_rq;
		}
1167

1168 1169 1170
		spin_unlock(&ctx->lock);
		__blk_mq_free_request(hctx, ctx, rq);
		return true;
1171
	}
1172
}
1173

1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186
struct blk_map_ctx {
	struct blk_mq_hw_ctx *hctx;
	struct blk_mq_ctx *ctx;
};

static struct request *blk_mq_map_request(struct request_queue *q,
					  struct bio *bio,
					  struct blk_map_ctx *data)
{
	struct blk_mq_hw_ctx *hctx;
	struct blk_mq_ctx *ctx;
	struct request *rq;
	int rw = bio_data_dir(bio);
1187
	struct blk_mq_alloc_data alloc_data;
1188

1189
	if (unlikely(blk_mq_queue_enter(q))) {
1190
		bio_endio(bio, -EIO);
1191
		return NULL;
1192 1193 1194 1195 1196
	}

	ctx = blk_mq_get_ctx(q);
	hctx = q->mq_ops->map_queue(q, ctx->cpu);

1197
	if (rw_is_sync(bio->bi_rw))
S
Shaohua Li 已提交
1198
		rw |= REQ_SYNC;
1199

1200
	trace_block_getrq(q, bio, rw);
1201 1202 1203
	blk_mq_set_alloc_data(&alloc_data, q, GFP_ATOMIC, false, ctx,
			hctx);
	rq = __blk_mq_alloc_request(&alloc_data, rw);
1204
	if (unlikely(!rq)) {
1205
		__blk_mq_run_hw_queue(hctx);
1206 1207
		blk_mq_put_ctx(ctx);
		trace_block_sleeprq(q, bio, rw);
1208 1209

		ctx = blk_mq_get_ctx(q);
1210
		hctx = q->mq_ops->map_queue(q, ctx->cpu);
1211 1212 1213 1214 1215
		blk_mq_set_alloc_data(&alloc_data, q,
				__GFP_WAIT|GFP_ATOMIC, false, ctx, hctx);
		rq = __blk_mq_alloc_request(&alloc_data, rw);
		ctx = alloc_data.ctx;
		hctx = alloc_data.hctx;
1216 1217 1218
	}

	hctx->queued++;
1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252
	data->hctx = hctx;
	data->ctx = ctx;
	return rq;
}

/*
 * Multiple hardware queue variant. This will not use per-process plugs,
 * but will attempt to bypass the hctx queueing if we can go straight to
 * hardware for SYNC IO.
 */
static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
{
	const int is_sync = rw_is_sync(bio->bi_rw);
	const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
	struct blk_map_ctx data;
	struct request *rq;

	blk_queue_bounce(q, &bio);

	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
		bio_endio(bio, -EIO);
		return;
	}

	rq = blk_mq_map_request(q, bio, &data);
	if (unlikely(!rq))
		return;

	if (unlikely(is_flush_fua)) {
		blk_mq_bio_to_request(rq, bio);
		blk_insert_flush(rq);
		goto run_queue;
	}

1253 1254 1255 1256 1257 1258
	/*
	 * If the driver supports defer issued based on 'last', then
	 * queue it up like normal since we can potentially save some
	 * CPU this way.
	 */
	if (is_sync && !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
1259 1260 1261 1262 1263
		struct blk_mq_queue_data bd = {
			.rq = rq,
			.list = NULL,
			.last = 1
		};
1264 1265 1266 1267 1268 1269 1270 1271 1272
		int ret;

		blk_mq_bio_to_request(rq, bio);

		/*
		 * For OK queue, we are done. For error, kill it. Any other
		 * error (busy), just add it to our list as we previously
		 * would have done
		 */
1273
		ret = q->mq_ops->queue_rq(data.hctx, &bd);
1274 1275 1276 1277 1278 1279 1280
		if (ret == BLK_MQ_RQ_QUEUE_OK)
			goto done;
		else {
			__blk_mq_requeue_request(rq);

			if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
				rq->errors = -EIO;
1281
				blk_mq_end_request(rq, rq->errors);
1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330
				goto done;
			}
		}
	}

	if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
		/*
		 * For a SYNC request, send it to the hardware immediately. For
		 * an ASYNC request, just ensure that we run it later on. The
		 * latter allows for merging opportunities and more efficient
		 * dispatching.
		 */
run_queue:
		blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
	}
done:
	blk_mq_put_ctx(data.ctx);
}

/*
 * Single hardware queue variant. This will attempt to use any per-process
 * plug for merging and IO deferral.
 */
static void blk_sq_make_request(struct request_queue *q, struct bio *bio)
{
	const int is_sync = rw_is_sync(bio->bi_rw);
	const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
	unsigned int use_plug, request_count = 0;
	struct blk_map_ctx data;
	struct request *rq;

	/*
	 * If we have multiple hardware queues, just go directly to
	 * one of those for sync IO.
	 */
	use_plug = !is_flush_fua && !is_sync;

	blk_queue_bounce(q, &bio);

	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
		bio_endio(bio, -EIO);
		return;
	}

	if (use_plug && !blk_queue_nomerges(q) &&
	    blk_attempt_plug_merge(q, bio, &request_count))
		return;

	rq = blk_mq_map_request(q, bio, &data);
1331 1332
	if (unlikely(!rq))
		return;
1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349

	if (unlikely(is_flush_fua)) {
		blk_mq_bio_to_request(rq, bio);
		blk_insert_flush(rq);
		goto run_queue;
	}

	/*
	 * A task plug currently exists. Since this is completely lockless,
	 * utilize that to temporarily store requests until the task is
	 * either done or scheduled away.
	 */
	if (use_plug) {
		struct blk_plug *plug = current->plug;

		if (plug) {
			blk_mq_bio_to_request(rq, bio);
S
Shaohua Li 已提交
1350
			if (list_empty(&plug->mq_list))
1351 1352 1353 1354 1355 1356
				trace_block_plug(q);
			else if (request_count >= BLK_MAX_REQUEST_COUNT) {
				blk_flush_plug_list(plug, false);
				trace_block_plug(q);
			}
			list_add_tail(&rq->queuelist, &plug->mq_list);
1357
			blk_mq_put_ctx(data.ctx);
1358 1359 1360 1361
			return;
		}
	}

1362 1363 1364 1365 1366 1367 1368 1369 1370
	if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
		/*
		 * For a SYNC request, send it to the hardware immediately. For
		 * an ASYNC request, just ensure that we run it later on. The
		 * latter allows for merging opportunities and more efficient
		 * dispatching.
		 */
run_queue:
		blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1371 1372
	}

1373
	blk_mq_put_ctx(data.ctx);
1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384
}

/*
 * Default mapping to a software queue, since we use one per CPU.
 */
struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
{
	return q->queue_hw_ctx[q->mq_map[cpu]];
}
EXPORT_SYMBOL(blk_mq_map_queue);

1385 1386
static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
		struct blk_mq_tags *tags, unsigned int hctx_idx)
1387
{
1388
	struct page *page;
1389

1390
	if (tags->rqs && set->ops->exit_request) {
1391
		int i;
1392

1393 1394
		for (i = 0; i < tags->nr_tags; i++) {
			if (!tags->rqs[i])
1395
				continue;
1396 1397
			set->ops->exit_request(set->driver_data, tags->rqs[i],
						hctx_idx, i);
1398
			tags->rqs[i] = NULL;
1399
		}
1400 1401
	}

1402 1403
	while (!list_empty(&tags->page_list)) {
		page = list_first_entry(&tags->page_list, struct page, lru);
1404
		list_del_init(&page->lru);
1405 1406 1407
		__free_pages(page, page->private);
	}

1408
	kfree(tags->rqs);
1409

1410
	blk_mq_free_tags(tags);
1411 1412 1413 1414
}

static size_t order_to_size(unsigned int order)
{
1415
	return (size_t)PAGE_SIZE << order;
1416 1417
}

1418 1419
static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
		unsigned int hctx_idx)
1420
{
1421
	struct blk_mq_tags *tags;
1422 1423 1424
	unsigned int i, j, entries_per_page, max_order = 4;
	size_t rq_size, left;

1425
	tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
S
Shaohua Li 已提交
1426 1427
				set->numa_node,
				BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1428 1429
	if (!tags)
		return NULL;
1430

1431 1432
	INIT_LIST_HEAD(&tags->page_list);

1433 1434 1435
	tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
				 GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
				 set->numa_node);
1436 1437 1438 1439
	if (!tags->rqs) {
		blk_mq_free_tags(tags);
		return NULL;
	}
1440 1441 1442 1443 1444

	/*
	 * rq_size is the size of the request plus driver payload, rounded
	 * to the cacheline size
	 */
1445
	rq_size = round_up(sizeof(struct request) + set->cmd_size,
1446
				cache_line_size());
1447
	left = rq_size * set->queue_depth;
1448

1449
	for (i = 0; i < set->queue_depth; ) {
1450 1451 1452 1453 1454 1455 1456 1457 1458
		int this_order = max_order;
		struct page *page;
		int to_do;
		void *p;

		while (left < order_to_size(this_order - 1) && this_order)
			this_order--;

		do {
1459 1460 1461
			page = alloc_pages_node(set->numa_node,
				GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
				this_order);
1462 1463 1464 1465 1466 1467 1468 1469 1470
			if (page)
				break;
			if (!this_order--)
				break;
			if (order_to_size(this_order) < rq_size)
				break;
		} while (1);

		if (!page)
1471
			goto fail;
1472 1473

		page->private = this_order;
1474
		list_add_tail(&page->lru, &tags->page_list);
1475 1476 1477

		p = page_address(page);
		entries_per_page = order_to_size(this_order) / rq_size;
1478
		to_do = min(entries_per_page, set->queue_depth - i);
1479 1480
		left -= to_do * rq_size;
		for (j = 0; j < to_do; j++) {
1481
			tags->rqs[i] = p;
1482 1483
			tags->rqs[i]->atomic_flags = 0;
			tags->rqs[i]->cmd_flags = 0;
1484 1485 1486
			if (set->ops->init_request) {
				if (set->ops->init_request(set->driver_data,
						tags->rqs[i], hctx_idx, i,
1487 1488
						set->numa_node)) {
					tags->rqs[i] = NULL;
1489
					goto fail;
1490
				}
1491 1492
			}

1493 1494 1495 1496 1497
			p += rq_size;
			i++;
		}
	}

1498
	return tags;
1499

1500 1501 1502
fail:
	blk_mq_free_rq_map(set, tags, hctx_idx);
	return NULL;
1503 1504
}

1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532
static void blk_mq_free_bitmap(struct blk_mq_ctxmap *bitmap)
{
	kfree(bitmap->map);
}

static int blk_mq_alloc_bitmap(struct blk_mq_ctxmap *bitmap, int node)
{
	unsigned int bpw = 8, total, num_maps, i;

	bitmap->bits_per_word = bpw;

	num_maps = ALIGN(nr_cpu_ids, bpw) / bpw;
	bitmap->map = kzalloc_node(num_maps * sizeof(struct blk_align_bitmap),
					GFP_KERNEL, node);
	if (!bitmap->map)
		return -ENOMEM;

	bitmap->map_size = num_maps;

	total = nr_cpu_ids;
	for (i = 0; i < num_maps; i++) {
		bitmap->map[i].depth = min(total, bitmap->bits_per_word);
		total -= bitmap->map[i].depth;
	}

	return 0;
}

1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603
static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
{
	struct request_queue *q = hctx->queue;
	struct blk_mq_ctx *ctx;
	LIST_HEAD(tmp);

	/*
	 * Move ctx entries to new CPU, if this one is going away.
	 */
	ctx = __blk_mq_get_ctx(q, cpu);

	spin_lock(&ctx->lock);
	if (!list_empty(&ctx->rq_list)) {
		list_splice_init(&ctx->rq_list, &tmp);
		blk_mq_hctx_clear_pending(hctx, ctx);
	}
	spin_unlock(&ctx->lock);

	if (list_empty(&tmp))
		return NOTIFY_OK;

	ctx = blk_mq_get_ctx(q);
	spin_lock(&ctx->lock);

	while (!list_empty(&tmp)) {
		struct request *rq;

		rq = list_first_entry(&tmp, struct request, queuelist);
		rq->mq_ctx = ctx;
		list_move_tail(&rq->queuelist, &ctx->rq_list);
	}

	hctx = q->mq_ops->map_queue(q, ctx->cpu);
	blk_mq_hctx_mark_pending(hctx, ctx);

	spin_unlock(&ctx->lock);

	blk_mq_run_hw_queue(hctx, true);
	blk_mq_put_ctx(ctx);
	return NOTIFY_OK;
}

static int blk_mq_hctx_cpu_online(struct blk_mq_hw_ctx *hctx, int cpu)
{
	struct request_queue *q = hctx->queue;
	struct blk_mq_tag_set *set = q->tag_set;

	if (set->tags[hctx->queue_num])
		return NOTIFY_OK;

	set->tags[hctx->queue_num] = blk_mq_init_rq_map(set, hctx->queue_num);
	if (!set->tags[hctx->queue_num])
		return NOTIFY_STOP;

	hctx->tags = set->tags[hctx->queue_num];
	return NOTIFY_OK;
}

static int blk_mq_hctx_notify(void *data, unsigned long action,
			      unsigned int cpu)
{
	struct blk_mq_hw_ctx *hctx = data;

	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
		return blk_mq_hctx_cpu_offline(hctx, cpu);
	else if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
		return blk_mq_hctx_cpu_online(hctx, cpu);

	return NOTIFY_OK;
}

1604 1605 1606 1607
static void blk_mq_exit_hctx(struct request_queue *q,
		struct blk_mq_tag_set *set,
		struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
1608 1609
	unsigned flush_start_tag = set->queue_depth;

1610 1611
	blk_mq_tag_idle(hctx);

1612 1613 1614 1615 1616
	if (set->ops->exit_request)
		set->ops->exit_request(set->driver_data,
				       hctx->fq->flush_rq, hctx_idx,
				       flush_start_tag + hctx_idx);

1617 1618 1619 1620
	if (set->ops->exit_hctx)
		set->ops->exit_hctx(hctx, hctx_idx);

	blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1621
	blk_free_flush_queue(hctx->fq);
1622 1623 1624 1625
	kfree(hctx->ctxs);
	blk_mq_free_bitmap(&hctx->ctx_map);
}

M
Ming Lei 已提交
1626 1627 1628 1629 1630 1631 1632 1633 1634
static void blk_mq_exit_hw_queues(struct request_queue *q,
		struct blk_mq_tag_set *set, int nr_queue)
{
	struct blk_mq_hw_ctx *hctx;
	unsigned int i;

	queue_for_each_hw_ctx(q, hctx, i) {
		if (i == nr_queue)
			break;
1635
		blk_mq_exit_hctx(q, set, hctx, i);
M
Ming Lei 已提交
1636 1637 1638 1639 1640 1641 1642 1643 1644
	}
}

static void blk_mq_free_hw_queues(struct request_queue *q,
		struct blk_mq_tag_set *set)
{
	struct blk_mq_hw_ctx *hctx;
	unsigned int i;

1645
	queue_for_each_hw_ctx(q, hctx, i)
M
Ming Lei 已提交
1646 1647 1648
		free_cpumask_var(hctx->cpumask);
}

1649 1650 1651
static int blk_mq_init_hctx(struct request_queue *q,
		struct blk_mq_tag_set *set,
		struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1652
{
1653
	int node;
1654
	unsigned flush_start_tag = set->queue_depth;
1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672

	node = hctx->numa_node;
	if (node == NUMA_NO_NODE)
		node = hctx->numa_node = set->numa_node;

	INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
	INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
	spin_lock_init(&hctx->lock);
	INIT_LIST_HEAD(&hctx->dispatch);
	hctx->queue = q;
	hctx->queue_num = hctx_idx;
	hctx->flags = set->flags;

	blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
					blk_mq_hctx_notify, hctx);
	blk_mq_register_cpu_notifier(&hctx->cpu_notifier);

	hctx->tags = set->tags[hctx_idx];
1673 1674

	/*
1675 1676
	 * Allocate space for all possible cpus to avoid allocation at
	 * runtime
1677
	 */
1678 1679 1680 1681
	hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
					GFP_KERNEL, node);
	if (!hctx->ctxs)
		goto unregister_cpu_notifier;
1682

1683 1684
	if (blk_mq_alloc_bitmap(&hctx->ctx_map, node))
		goto free_ctxs;
1685

1686
	hctx->nr_ctx = 0;
1687

1688 1689 1690
	if (set->ops->init_hctx &&
	    set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
		goto free_bitmap;
1691

1692 1693 1694
	hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
	if (!hctx->fq)
		goto exit_hctx;
1695

1696 1697 1698 1699 1700
	if (set->ops->init_request &&
	    set->ops->init_request(set->driver_data,
				   hctx->fq->flush_rq, hctx_idx,
				   flush_start_tag + hctx_idx, node))
		goto free_fq;
1701

1702
	return 0;
1703

1704 1705 1706 1707 1708
 free_fq:
	kfree(hctx->fq);
 exit_hctx:
	if (set->ops->exit_hctx)
		set->ops->exit_hctx(hctx, hctx_idx);
1709 1710 1711 1712 1713 1714
 free_bitmap:
	blk_mq_free_bitmap(&hctx->ctx_map);
 free_ctxs:
	kfree(hctx->ctxs);
 unregister_cpu_notifier:
	blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1715

1716 1717
	return -1;
}
1718

1719 1720 1721 1722 1723
static int blk_mq_init_hw_queues(struct request_queue *q,
		struct blk_mq_tag_set *set)
{
	struct blk_mq_hw_ctx *hctx;
	unsigned int i;
1724

1725 1726 1727 1728 1729
	/*
	 * Initialize hardware queues
	 */
	queue_for_each_hw_ctx(q, hctx, i) {
		if (blk_mq_init_hctx(q, set, hctx, i))
1730 1731 1732 1733 1734 1735 1736 1737 1738
			break;
	}

	if (i == q->nr_hw_queues)
		return 0;

	/*
	 * Init failed
	 */
M
Ming Lei 已提交
1739
	blk_mq_exit_hw_queues(q, set, i);
1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762

	return 1;
}

static void blk_mq_init_cpu_queues(struct request_queue *q,
				   unsigned int nr_hw_queues)
{
	unsigned int i;

	for_each_possible_cpu(i) {
		struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
		struct blk_mq_hw_ctx *hctx;

		memset(__ctx, 0, sizeof(*__ctx));
		__ctx->cpu = i;
		spin_lock_init(&__ctx->lock);
		INIT_LIST_HEAD(&__ctx->rq_list);
		__ctx->queue = q;

		/* If the cpu isn't online, the cpu is mapped to first hctx */
		if (!cpu_online(i))
			continue;

1763 1764 1765 1766
		hctx = q->mq_ops->map_queue(q, i);
		cpumask_set_cpu(i, hctx->cpumask);
		hctx->nr_ctx++;

1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782
		/*
		 * Set local node, IFF we have more than one hw queue. If
		 * not, we remain on the home node of the device
		 */
		if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
			hctx->numa_node = cpu_to_node(i);
	}
}

static void blk_mq_map_swqueue(struct request_queue *q)
{
	unsigned int i;
	struct blk_mq_hw_ctx *hctx;
	struct blk_mq_ctx *ctx;

	queue_for_each_hw_ctx(q, hctx, i) {
1783
		cpumask_clear(hctx->cpumask);
1784 1785 1786 1787 1788 1789 1790 1791
		hctx->nr_ctx = 0;
	}

	/*
	 * Map software to hardware queues
	 */
	queue_for_each_ctx(q, ctx, i) {
		/* If the cpu isn't online, the cpu is mapped to first hctx */
1792 1793 1794
		if (!cpu_online(i))
			continue;

1795
		hctx = q->mq_ops->map_queue(q, i);
1796
		cpumask_set_cpu(i, hctx->cpumask);
1797 1798 1799
		ctx->index_hw = hctx->nr_ctx;
		hctx->ctxs[hctx->nr_ctx++] = ctx;
	}
1800 1801

	queue_for_each_hw_ctx(q, hctx, i) {
1802
		/*
1803 1804
		 * If no software queues are mapped to this hardware queue,
		 * disable it and free the request entries.
1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819
		 */
		if (!hctx->nr_ctx) {
			struct blk_mq_tag_set *set = q->tag_set;

			if (set->tags[i]) {
				blk_mq_free_rq_map(set, set->tags[i], i);
				set->tags[i] = NULL;
				hctx->tags = NULL;
			}
			continue;
		}

		/*
		 * Initialize batch roundrobin counts
		 */
1820 1821 1822
		hctx->next_cpu = cpumask_first(hctx->cpumask);
		hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
	}
1823 1824
}

1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870
static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set)
{
	struct blk_mq_hw_ctx *hctx;
	struct request_queue *q;
	bool shared;
	int i;

	if (set->tag_list.next == set->tag_list.prev)
		shared = false;
	else
		shared = true;

	list_for_each_entry(q, &set->tag_list, tag_set_list) {
		blk_mq_freeze_queue(q);

		queue_for_each_hw_ctx(q, hctx, i) {
			if (shared)
				hctx->flags |= BLK_MQ_F_TAG_SHARED;
			else
				hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
		}
		blk_mq_unfreeze_queue(q);
	}
}

static void blk_mq_del_queue_tag_set(struct request_queue *q)
{
	struct blk_mq_tag_set *set = q->tag_set;

	mutex_lock(&set->tag_list_lock);
	list_del_init(&q->tag_set_list);
	blk_mq_update_tag_set_depth(set);
	mutex_unlock(&set->tag_list_lock);
}

static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
				     struct request_queue *q)
{
	q->tag_set = set;

	mutex_lock(&set->tag_list_lock);
	list_add_tail(&q->tag_set_list, &set->tag_list);
	blk_mq_update_tag_set_depth(set);
	mutex_unlock(&set->tag_list_lock);
}

1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891
/*
 * It is the actual release handler for mq, but we do it from
 * request queue's release handler for avoiding use-after-free
 * and headache because q->mq_kobj shouldn't have been introduced,
 * but we can't group ctx/kctx kobj without it.
 */
void blk_mq_release(struct request_queue *q)
{
	struct blk_mq_hw_ctx *hctx;
	unsigned int i;

	/* hctx kobj stays in hctx */
	queue_for_each_hw_ctx(q, hctx, i)
		kfree(hctx);

	kfree(q->queue_hw_ctx);

	/* ctx kobj stays in queue_ctx */
	free_percpu(q->queue_ctx);
}

1892
struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
1893 1894
{
	struct blk_mq_hw_ctx **hctxs;
1895
	struct blk_mq_ctx __percpu *ctx;
1896
	struct request_queue *q;
1897
	unsigned int *map;
1898 1899 1900 1901 1902 1903
	int i;

	ctx = alloc_percpu(struct blk_mq_ctx);
	if (!ctx)
		return ERR_PTR(-ENOMEM);

1904 1905
	hctxs = kmalloc_node(set->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
			set->numa_node);
1906 1907 1908 1909

	if (!hctxs)
		goto err_percpu;

1910 1911 1912 1913
	map = blk_mq_make_queue_map(set);
	if (!map)
		goto err_map;

1914
	for (i = 0; i < set->nr_hw_queues; i++) {
1915 1916
		int node = blk_mq_hw_queue_to_node(map, i);

1917 1918
		hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
					GFP_KERNEL, node);
1919 1920 1921
		if (!hctxs[i])
			goto err_hctxs;

1922 1923
		if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
						node))
1924 1925
			goto err_hctxs;

1926
		atomic_set(&hctxs[i]->nr_active, 0);
1927
		hctxs[i]->numa_node = node;
1928 1929 1930
		hctxs[i]->queue_num = i;
	}

1931
	q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
1932 1933 1934
	if (!q)
		goto err_hctxs;

1935 1936 1937 1938
	/*
	 * Init percpu_ref in atomic mode so that it's faster to shutdown.
	 * See blk_register_queue() for details.
	 */
1939
	if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release,
1940
			    PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
1941
		goto err_mq_usage;
1942

1943 1944 1945 1946
	setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
	blk_queue_rq_timeout(q, 30000);

	q->nr_queues = nr_cpu_ids;
1947
	q->nr_hw_queues = set->nr_hw_queues;
1948
	q->mq_map = map;
1949 1950 1951 1952

	q->queue_ctx = ctx;
	q->queue_hw_ctx = hctxs;

1953
	q->mq_ops = set->ops;
1954
	q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
1955

1956 1957 1958
	if (!(set->flags & BLK_MQ_F_SG_MERGE))
		q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;

1959 1960
	q->sg_reserved_size = INT_MAX;

1961 1962 1963 1964
	INIT_WORK(&q->requeue_work, blk_mq_requeue_work);
	INIT_LIST_HEAD(&q->requeue_list);
	spin_lock_init(&q->requeue_lock);

1965 1966 1967 1968 1969
	if (q->nr_hw_queues > 1)
		blk_queue_make_request(q, blk_mq_make_request);
	else
		blk_queue_make_request(q, blk_sq_make_request);

1970 1971
	if (set->timeout)
		blk_queue_rq_timeout(q, set->timeout);
1972

1973 1974 1975 1976 1977
	/*
	 * Do this after blk_queue_make_request() overrides it...
	 */
	q->nr_requests = set->queue_depth;

1978 1979
	if (set->ops->complete)
		blk_queue_softirq_done(q, set->ops->complete);
1980

1981
	blk_mq_init_cpu_queues(q, set->nr_hw_queues);
1982

1983
	if (blk_mq_init_hw_queues(q, set))
1984
		goto err_mq_usage;
1985

1986 1987 1988 1989
	mutex_lock(&all_q_mutex);
	list_add_tail(&q->all_q_node, &all_q_list);
	mutex_unlock(&all_q_mutex);

1990 1991
	blk_mq_add_queue_tag_set(set, q);

1992 1993
	blk_mq_map_swqueue(q);

1994
	return q;
1995

1996
err_mq_usage:
1997 1998
	blk_cleanup_queue(q);
err_hctxs:
1999
	kfree(map);
2000
	for (i = 0; i < set->nr_hw_queues; i++) {
2001 2002
		if (!hctxs[i])
			break;
2003
		free_cpumask_var(hctxs[i]->cpumask);
2004
		kfree(hctxs[i]);
2005
	}
2006
err_map:
2007 2008 2009 2010 2011 2012 2013 2014 2015
	kfree(hctxs);
err_percpu:
	free_percpu(ctx);
	return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(blk_mq_init_queue);

void blk_mq_free_queue(struct request_queue *q)
{
M
Ming Lei 已提交
2016
	struct blk_mq_tag_set	*set = q->tag_set;
2017

2018 2019
	blk_mq_del_queue_tag_set(q);

M
Ming Lei 已提交
2020 2021
	blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
	blk_mq_free_hw_queues(q, set);
2022

2023
	percpu_ref_exit(&q->mq_usage_counter);
2024

2025 2026 2027 2028 2029 2030 2031 2032 2033 2034
	kfree(q->mq_map);

	q->mq_map = NULL;

	mutex_lock(&all_q_mutex);
	list_del_init(&q->all_q_node);
	mutex_unlock(&all_q_mutex);
}

/* Basically redo blk_mq_init_queue with queue frozen */
2035
static void blk_mq_queue_reinit(struct request_queue *q)
2036
{
2037
	WARN_ON_ONCE(!q->mq_freeze_depth);
2038

2039 2040
	blk_mq_sysfs_unregister(q);

2041 2042 2043 2044 2045 2046 2047 2048 2049 2050
	blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);

	/*
	 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
	 * we should change hctx numa_node according to new topology (this
	 * involves free and re-allocate memory, worthy doing?)
	 */

	blk_mq_map_swqueue(q);

2051
	blk_mq_sysfs_register(q);
2052 2053
}

2054 2055
static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
				      unsigned long action, void *hcpu)
2056 2057 2058 2059
{
	struct request_queue *q;

	/*
2060 2061 2062 2063
	 * Before new mappings are established, hotadded cpu might already
	 * start handling requests. This doesn't break anything as we map
	 * offline CPUs to first hardware queue. We will re-init the queue
	 * below to get optimal settings.
2064 2065 2066 2067 2068 2069
	 */
	if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
	    action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
		return NOTIFY_OK;

	mutex_lock(&all_q_mutex);
2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082

	/*
	 * We need to freeze and reinit all existing queues.  Freezing
	 * involves synchronous wait for an RCU grace period and doing it
	 * one by one may take a long time.  Start freezing all queues in
	 * one swoop and then wait for the completions so that freezing can
	 * take place in parallel.
	 */
	list_for_each_entry(q, &all_q_list, all_q_node)
		blk_mq_freeze_queue_start(q);
	list_for_each_entry(q, &all_q_list, all_q_node)
		blk_mq_freeze_queue_wait(q);

2083 2084
	list_for_each_entry(q, &all_q_list, all_q_node)
		blk_mq_queue_reinit(q);
2085 2086 2087 2088

	list_for_each_entry(q, &all_q_list, all_q_node)
		blk_mq_unfreeze_queue(q);

2089 2090 2091 2092
	mutex_unlock(&all_q_mutex);
	return NOTIFY_OK;
}

2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146
static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
{
	int i;

	for (i = 0; i < set->nr_hw_queues; i++) {
		set->tags[i] = blk_mq_init_rq_map(set, i);
		if (!set->tags[i])
			goto out_unwind;
	}

	return 0;

out_unwind:
	while (--i >= 0)
		blk_mq_free_rq_map(set, set->tags[i], i);

	return -ENOMEM;
}

/*
 * Allocate the request maps associated with this tag_set. Note that this
 * may reduce the depth asked for, if memory is tight. set->queue_depth
 * will be updated to reflect the allocated depth.
 */
static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
{
	unsigned int depth;
	int err;

	depth = set->queue_depth;
	do {
		err = __blk_mq_alloc_rq_maps(set);
		if (!err)
			break;

		set->queue_depth >>= 1;
		if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
			err = -ENOMEM;
			break;
		}
	} while (set->queue_depth);

	if (!set->queue_depth || err) {
		pr_err("blk-mq: failed to allocate request map\n");
		return -ENOMEM;
	}

	if (depth != set->queue_depth)
		pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
						depth, set->queue_depth);

	return 0;
}

2147 2148 2149 2150 2151 2152
/*
 * Alloc a tag set to be associated with one or more request queues.
 * May fail with EINVAL for various error conditions. May adjust the
 * requested depth down, if if it too large. In that case, the set
 * value will be stored in set->queue_depth.
 */
2153 2154
int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
{
B
Bart Van Assche 已提交
2155 2156
	BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);

2157 2158
	if (!set->nr_hw_queues)
		return -EINVAL;
2159
	if (!set->queue_depth)
2160 2161 2162 2163
		return -EINVAL;
	if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
		return -EINVAL;

2164
	if (!set->nr_hw_queues || !set->ops->queue_rq || !set->ops->map_queue)
2165 2166
		return -EINVAL;

2167 2168 2169 2170 2171
	if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
		pr_info("blk-mq: reduced tag depth to %u\n",
			BLK_MQ_MAX_DEPTH);
		set->queue_depth = BLK_MQ_MAX_DEPTH;
	}
2172

2173 2174 2175 2176 2177 2178 2179 2180 2181 2182
	/*
	 * If a crashdump is active, then we are potentially in a very
	 * memory constrained environment. Limit us to 1 queue and
	 * 64 tags to prevent using too much memory.
	 */
	if (is_kdump_kernel()) {
		set->nr_hw_queues = 1;
		set->queue_depth = min(64U, set->queue_depth);
	}

M
Ming Lei 已提交
2183 2184
	set->tags = kmalloc_node(set->nr_hw_queues *
				 sizeof(struct blk_mq_tags *),
2185 2186
				 GFP_KERNEL, set->numa_node);
	if (!set->tags)
2187
		return -ENOMEM;
2188

2189 2190
	if (blk_mq_alloc_rq_maps(set))
		goto enomem;
2191

2192 2193 2194
	mutex_init(&set->tag_list_lock);
	INIT_LIST_HEAD(&set->tag_list);

2195
	return 0;
2196
enomem:
2197 2198
	kfree(set->tags);
	set->tags = NULL;
2199 2200 2201 2202 2203 2204 2205 2206
	return -ENOMEM;
}
EXPORT_SYMBOL(blk_mq_alloc_tag_set);

void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
{
	int i;

2207 2208 2209 2210 2211
	for (i = 0; i < set->nr_hw_queues; i++) {
		if (set->tags[i])
			blk_mq_free_rq_map(set, set->tags[i], i);
	}

M
Ming Lei 已提交
2212
	kfree(set->tags);
2213
	set->tags = NULL;
2214 2215 2216
}
EXPORT_SYMBOL(blk_mq_free_tag_set);

2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238
int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
{
	struct blk_mq_tag_set *set = q->tag_set;
	struct blk_mq_hw_ctx *hctx;
	int i, ret;

	if (!set || nr > set->queue_depth)
		return -EINVAL;

	ret = 0;
	queue_for_each_hw_ctx(q, hctx, i) {
		ret = blk_mq_tag_update_depth(hctx->tags, nr);
		if (ret)
			break;
	}

	if (!ret)
		q->nr_requests = nr;

	return ret;
}

2239 2240 2241 2242 2243 2244 2245 2246 2247 2248
void blk_mq_disable_hotplug(void)
{
	mutex_lock(&all_q_mutex);
}

void blk_mq_enable_hotplug(void)
{
	mutex_unlock(&all_q_mutex);
}

2249 2250 2251 2252
static int __init blk_mq_init(void)
{
	blk_mq_cpu_init();

2253
	hotcpu_notifier(blk_mq_queue_reinit_notify, 0);
2254 2255 2256 2257

	return 0;
}
subsys_initcall(blk_mq_init);