blk-mq.c 33.3 KB
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#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>

#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);

static struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
					   unsigned int cpu)
{
	return per_cpu_ptr(q->queue_ctx, cpu);
}

/*
 * This assumes per-cpu software queueing queues. They could be per-node
 * as well, for instance. For now this is hardcoded as-is. Note that we don't
 * care about preemption, since we know the ctx's are persistent. This does
 * mean that we can't rely on ctx always matching the currently running CPU.
 */
static struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
{
	return __blk_mq_get_ctx(q, get_cpu());
}

static void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
{
	put_cpu();
}

/*
 * 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;

	for (i = 0; i < hctx->nr_ctx_map; i++)
		if (hctx->ctx_map[i])
			return true;

	return false;
}

/*
 * 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)
{
	if (!test_bit(ctx->index_hw, hctx->ctx_map))
		set_bit(ctx->index_hw, hctx->ctx_map);
}

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static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
					      gfp_t gfp, bool reserved)
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{
	struct request *rq;
	unsigned int tag;

	tag = blk_mq_get_tag(hctx->tags, gfp, reserved);
	if (tag != BLK_MQ_TAG_FAIL) {
		rq = hctx->rqs[tag];
		rq->tag = tag;

		return rq;
	}

	return NULL;
}

static int blk_mq_queue_enter(struct request_queue *q)
{
	int ret;

	__percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
	smp_wmb();
	/* we have problems to freeze the queue if it's initializing */
	if (!blk_queue_bypass(q) || !blk_queue_init_done(q))
		return 0;

	__percpu_counter_add(&q->mq_usage_counter, -1, 1000000);

	spin_lock_irq(q->queue_lock);
	ret = wait_event_interruptible_lock_irq(q->mq_freeze_wq,
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		!blk_queue_bypass(q) || blk_queue_dying(q),
		*q->queue_lock);
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	/* inc usage with lock hold to avoid freeze_queue runs here */
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	if (!ret && !blk_queue_dying(q))
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		__percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
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	else if (blk_queue_dying(q))
		ret = -ENODEV;
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	spin_unlock_irq(q->queue_lock);

	return ret;
}

static void blk_mq_queue_exit(struct request_queue *q)
{
	__percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
}

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static void __blk_mq_drain_queue(struct request_queue *q)
{
	while (true) {
		s64 count;

		spin_lock_irq(q->queue_lock);
		count = percpu_counter_sum(&q->mq_usage_counter);
		spin_unlock_irq(q->queue_lock);

		if (count == 0)
			break;
		blk_mq_run_queues(q, false);
		msleep(10);
	}
}

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/*
 * Guarantee no request is in use, so we can change any data structure of
 * the queue afterward.
 */
static void blk_mq_freeze_queue(struct request_queue *q)
{
	bool drain;

	spin_lock_irq(q->queue_lock);
	drain = !q->bypass_depth++;
	queue_flag_set(QUEUE_FLAG_BYPASS, q);
	spin_unlock_irq(q->queue_lock);

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	if (drain)
		__blk_mq_drain_queue(q);
}
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void blk_mq_drain_queue(struct request_queue *q)
{
	__blk_mq_drain_queue(q);
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}

static void blk_mq_unfreeze_queue(struct request_queue *q)
{
	bool wake = false;

	spin_lock_irq(q->queue_lock);
	if (!--q->bypass_depth) {
		queue_flag_clear(QUEUE_FLAG_BYPASS, q);
		wake = true;
	}
	WARN_ON_ONCE(q->bypass_depth < 0);
	spin_unlock_irq(q->queue_lock);
	if (wake)
		wake_up_all(&q->mq_freeze_wq);
}

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);

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

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	rq->mq_ctx = ctx;
	rq->cmd_flags = rw_flags;
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	rq->start_time = jiffies;
	set_start_time_ns(rq);
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	ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
}

static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
						   int rw, gfp_t gfp,
						   bool reserved)
{
	struct request *rq;

	do {
		struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
		struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);

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		rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved);
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		if (rq) {
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			blk_mq_rq_ctx_init(q, ctx, rq, rw);
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			break;
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		}
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		blk_mq_put_ctx(ctx);
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		if (!(gfp & __GFP_WAIT))
			break;

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		__blk_mq_run_hw_queue(hctx);
		blk_mq_wait_for_tags(hctx->tags);
	} while (1);

	return rq;
}

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struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp)
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{
	struct request *rq;

	if (blk_mq_queue_enter(q))
		return NULL;

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	rq = blk_mq_alloc_request_pinned(q, rw, gfp, false);
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	if (rq)
		blk_mq_put_ctx(rq->mq_ctx);
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	return rq;
}

struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
					      gfp_t gfp)
{
	struct request *rq;

	if (blk_mq_queue_enter(q))
		return NULL;

	rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
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	if (rq)
		blk_mq_put_ctx(rq->mq_ctx);
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	return rq;
}
EXPORT_SYMBOL(blk_mq_alloc_reserved_request);

/*
 * Re-init and set pdu, if we have it
 */
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void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)
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{
	blk_rq_init(hctx->queue, rq);

	if (hctx->cmd_size)
		rq->special = blk_mq_rq_to_pdu(rq);
}

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;

	blk_mq_rq_init(hctx, rq);
	blk_mq_put_tag(hctx->tags, tag);

	blk_mq_queue_exit(q);
}

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

	ctx->rq_completed[rq_is_sync(rq)]++;

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

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bool blk_mq_end_io_partial(struct request *rq, int error, unsigned int nr_bytes)
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{
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	if (blk_update_request(rq, error, blk_rq_bytes(rq)))
		return true;
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	blk_account_io_done(rq);

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	if (rq->end_io)
		rq->end_io(rq, error);
	else
		blk_mq_free_request(rq);
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	return false;
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}
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EXPORT_SYMBOL(blk_mq_end_io_partial);
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static void __blk_mq_complete_request_remote(void *data)
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{
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	struct request *rq = data;
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	rq->q->softirq_done_fn(rq);
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}

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void __blk_mq_complete_request(struct request *rq)
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{
	struct blk_mq_ctx *ctx = rq->mq_ctx;
	int cpu;

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	if (!ctx->ipi_redirect) {
		rq->q->softirq_done_fn(rq);
		return;
	}
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	cpu = get_cpu();
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	if (cpu != ctx->cpu && cpu_online(ctx->cpu)) {
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		rq->csd.func = __blk_mq_complete_request_remote;
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		rq->csd.info = rq;
		rq->csd.flags = 0;
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		smp_call_function_single_async(ctx->cpu, &rq->csd);
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	} else {
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		rq->q->softirq_done_fn(rq);
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	}
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	put_cpu();
}
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/**
 * 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)
{
	if (unlikely(blk_should_fake_timeout(rq->q)))
		return;
	if (!blk_mark_rq_complete(rq))
		__blk_mq_complete_request(rq);
}
EXPORT_SYMBOL(blk_mq_complete_request);
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static void blk_mq_start_request(struct request *rq, bool last)
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{
	struct request_queue *q = rq->q;

	trace_block_rq_issue(q, rq);

	/*
	 * Just mark start time and set the started bit. Due to memory
	 * ordering, we know we'll see the correct deadline as long as
	 * REQ_ATOMIC_STARTED is seen.
	 */
	rq->deadline = jiffies + q->rq_timeout;
	set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
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	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++;
	}

	/*
	 * Flag the last request in the series so that drivers know when IO
	 * should be kicked off, if they don't do it on a per-request basis.
	 *
	 * Note: the flag isn't the only condition drivers should do kick off.
	 * If drive is busy, the last request might not have the bit set.
	 */
	if (last)
		rq->cmd_flags |= REQ_END;
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}

static void blk_mq_requeue_request(struct request *rq)
{
	struct request_queue *q = rq->q;

	trace_block_rq_requeue(q, rq);
	clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
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	rq->cmd_flags &= ~REQ_END;

	if (q->dma_drain_size && blk_rq_bytes(rq))
		rq->nr_phys_segments--;
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}

struct blk_mq_timeout_data {
	struct blk_mq_hw_ctx *hctx;
	unsigned long *next;
	unsigned int *next_set;
};

static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
{
	struct blk_mq_timeout_data *data = __data;
	struct blk_mq_hw_ctx *hctx = data->hctx;
	unsigned int tag;

	 /* It may not be in flight yet (this is where
	 * the REQ_ATOMIC_STARTED flag comes in). The requests are
	 * statically allocated, so we know it's always safe to access the
	 * memory associated with a bit offset into ->rqs[].
	 */
	tag = 0;
	do {
		struct request *rq;

		tag = find_next_zero_bit(free_tags, hctx->queue_depth, tag);
		if (tag >= hctx->queue_depth)
			break;

		rq = hctx->rqs[tag++];

		if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
			continue;

		blk_rq_check_expired(rq, data->next, data->next_set);
	} while (1);
}

static void blk_mq_hw_ctx_check_timeout(struct blk_mq_hw_ctx *hctx,
					unsigned long *next,
					unsigned int *next_set)
{
	struct blk_mq_timeout_data data = {
		.hctx		= hctx,
		.next		= next,
		.next_set	= next_set,
	};

	/*
	 * Ask the tagging code to iterate busy requests, so we can
	 * check them for timeout.
	 */
	blk_mq_tag_busy_iter(hctx->tags, blk_mq_timeout_check, &data);
}

static void blk_mq_rq_timer(unsigned long data)
{
	struct request_queue *q = (struct request_queue *) data;
	struct blk_mq_hw_ctx *hctx;
	unsigned long next = 0;
	int i, next_set = 0;

	queue_for_each_hw_ctx(q, hctx, i)
		blk_mq_hw_ctx_check_timeout(hctx, &next, &next_set);

	if (next_set)
		mod_timer(&q->timeout, round_jiffies_up(next));
}

/*
 * 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;
}

void blk_mq_add_timer(struct request *rq)
{
	__blk_add_timer(rq, NULL);
}

/*
 * 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 blk_mq_ctx *ctx;
	struct request *rq;
	LIST_HEAD(rq_list);
	int bit, queued;

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	if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
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		return;

	hctx->run++;

	/*
	 * Touch any software queue that has pending entries.
	 */
	for_each_set_bit(bit, hctx->ctx_map, hctx->nr_ctx) {
		clear_bit(bit, hctx->ctx_map);
		ctx = hctx->ctxs[bit];
		BUG_ON(bit != ctx->index_hw);

		spin_lock(&ctx->lock);
		list_splice_tail_init(&ctx->rq_list, &rq_list);
		spin_unlock(&ctx->lock);
	}

	/*
	 * 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);
	}

	/*
	 * Delete and return all entries from our dispatch list
	 */
	queued = 0;

	/*
	 * Now process all the entries, sending them to the driver.
	 */
	while (!list_empty(&rq_list)) {
		int ret;

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

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		blk_mq_start_request(rq, list_empty(&rq_list));
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		ret = q->mq_ops->queue_rq(hctx, rq);
		switch (ret) {
		case BLK_MQ_RQ_QUEUE_OK:
			queued++;
			continue;
		case BLK_MQ_RQ_QUEUE_BUSY:
			/*
			 * FIXME: we should have a mechanism to stop the queue
			 * like blk_stop_queue, otherwise we will waste cpu
			 * time
			 */
			list_add(&rq->queuelist, &rq_list);
			blk_mq_requeue_request(rq);
			break;
		default:
			pr_err("blk-mq: bad return on queue: %d\n", ret);
		case BLK_MQ_RQ_QUEUE_ERROR:
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			rq->errors = -EIO;
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			blk_mq_end_io(rq, rq->errors);
			break;
		}

		if (ret == BLK_MQ_RQ_QUEUE_BUSY)
			break;
	}

	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);
	}
}

void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
{
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	if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
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		return;

	if (!async)
		__blk_mq_run_hw_queue(hctx);
	else {
		struct request_queue *q = hctx->queue;

		kblockd_schedule_delayed_work(q, &hctx->delayed_work, 0);
	}
}

void blk_mq_run_queues(struct request_queue *q, bool async)
{
	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)) ||
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		    test_bit(BLK_MQ_S_STOPPED, &hctx->state))
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			continue;

		blk_mq_run_hw_queue(hctx, async);
	}
}
EXPORT_SYMBOL(blk_mq_run_queues);

void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
	cancel_delayed_work(&hctx->delayed_work);
	set_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queue);

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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);

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void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
{
	clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
	__blk_mq_run_hw_queue(hctx);
}
EXPORT_SYMBOL(blk_mq_start_hw_queue);

void blk_mq_start_stopped_hw_queues(struct request_queue *q)
{
	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);
		blk_mq_run_hw_queue(hctx, true);
	}
}
EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);

static void blk_mq_work_fn(struct work_struct *work)
{
	struct blk_mq_hw_ctx *hctx;

	hctx = container_of(work, struct blk_mq_hw_ctx, delayed_work.work);
	__blk_mq_run_hw_queue(hctx);
}

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

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	trace_block_rq_insert(hctx->queue, rq);

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	if (at_head)
		list_add(&rq->queuelist, &ctx->rq_list);
	else
		list_add_tail(&rq->queuelist, &ctx->rq_list);
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	blk_mq_hctx_mark_pending(hctx, ctx);

	/*
	 * We do this early, to ensure we are on the right CPU.
	 */
	blk_mq_add_timer(rq);
}

700 701
void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
		bool async)
702
{
703
	struct request_queue *q = rq->q;
704
	struct blk_mq_hw_ctx *hctx;
705 706 707 708 709
	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;
710 711 712

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

713 714
	if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA) &&
	    !(rq->cmd_flags & (REQ_FLUSH_SEQ))) {
715 716 717
		blk_insert_flush(rq);
	} else {
		spin_lock(&ctx->lock);
718
		__blk_mq_insert_request(hctx, rq, at_head);
719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756
		spin_unlock(&ctx->lock);
	}

	blk_mq_put_ctx(current_ctx);

	if (run_queue)
		blk_mq_run_hw_queue(hctx, async);
}

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;
757
		__blk_mq_insert_request(hctx, rq, false);
758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846
	}
	spin_unlock(&ctx->lock);

	blk_mq_put_ctx(current_ctx);

	blk_mq_run_hw_queue(hctx, from_schedule);
}

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);
	blk_account_io_start(rq, 1);
}

static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
{
	struct blk_mq_hw_ctx *hctx;
	struct blk_mq_ctx *ctx;
	const int is_sync = rw_is_sync(bio->bi_rw);
	const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
	int rw = bio_data_dir(bio);
	struct request *rq;
	unsigned int use_plug, request_count = 0;

	/*
	 * If we have multiple hardware queues, just go directly to
	 * one of those for sync IO.
	 */
	use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);

	blk_queue_bounce(q, &bio);

847 848 849 850 851
	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
		bio_endio(bio, -EIO);
		return;
	}

852 853 854 855 856 857 858 859 860 861 862
	if (use_plug && blk_attempt_plug_merge(q, bio, &request_count))
		return;

	if (blk_mq_queue_enter(q)) {
		bio_endio(bio, -EIO);
		return;
	}

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

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	if (is_sync)
		rw |= REQ_SYNC;
865
	trace_block_getrq(q, bio, rw);
866
	rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false);
867
	if (likely(rq))
868
		blk_mq_rq_ctx_init(q, ctx, rq, rw);
869 870 871
	else {
		blk_mq_put_ctx(ctx);
		trace_block_sleeprq(q, bio, rw);
872 873
		rq = blk_mq_alloc_request_pinned(q, rw, __GFP_WAIT|GFP_ATOMIC,
							false);
874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896
		ctx = rq->mq_ctx;
		hctx = q->mq_ops->map_queue(q, ctx->cpu);
	}

	hctx->queued++;

	if (unlikely(is_flush_fua)) {
		blk_mq_bio_to_request(rq, bio);
		blk_mq_put_ctx(ctx);
		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);
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			if (list_empty(&plug->mq_list))
898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915
				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);
			blk_mq_put_ctx(ctx);
			return;
		}
	}

	spin_lock(&ctx->lock);

	if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
	    blk_mq_attempt_merge(q, ctx, bio))
		__blk_mq_free_request(hctx, ctx, rq);
	else {
		blk_mq_bio_to_request(rq, bio);
916
		__blk_mq_insert_request(hctx, rq, false);
917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996
	}

	spin_unlock(&ctx->lock);
	blk_mq_put_ctx(ctx);

	/*
	 * 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(hctx, !is_sync || is_flush_fua);
}

/*
 * 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);

struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_reg *reg,
						   unsigned int hctx_index)
{
	return kmalloc_node(sizeof(struct blk_mq_hw_ctx),
				GFP_KERNEL | __GFP_ZERO, reg->numa_node);
}
EXPORT_SYMBOL(blk_mq_alloc_single_hw_queue);

void blk_mq_free_single_hw_queue(struct blk_mq_hw_ctx *hctx,
				 unsigned int hctx_index)
{
	kfree(hctx);
}
EXPORT_SYMBOL(blk_mq_free_single_hw_queue);

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

	if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
		return;

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

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

	if (list_empty(&tmp))
		return;

	ctx = blk_mq_get_ctx(hctx->queue);
	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);
	}

	blk_mq_hctx_mark_pending(hctx, ctx);

	spin_unlock(&ctx->lock);
	blk_mq_put_ctx(ctx);
}

997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036
static int blk_mq_init_hw_commands(struct blk_mq_hw_ctx *hctx,
				   int (*init)(void *, struct blk_mq_hw_ctx *,
					struct request *, unsigned int),
				   void *data)
{
	unsigned int i;
	int ret = 0;

	for (i = 0; i < hctx->queue_depth; i++) {
		struct request *rq = hctx->rqs[i];

		ret = init(data, hctx, rq, i);
		if (ret)
			break;
	}

	return ret;
}

int blk_mq_init_commands(struct request_queue *q,
			 int (*init)(void *, struct blk_mq_hw_ctx *,
					struct request *, unsigned int),
			 void *data)
{
	struct blk_mq_hw_ctx *hctx;
	unsigned int i;
	int ret = 0;

	queue_for_each_hw_ctx(q, hctx, i) {
		ret = blk_mq_init_hw_commands(hctx, init, data);
		if (ret)
			break;
	}

	return ret;
}
EXPORT_SYMBOL(blk_mq_init_commands);

static void blk_mq_free_hw_commands(struct blk_mq_hw_ctx *hctx,
				    void (*free)(void *, struct blk_mq_hw_ctx *,
1037 1038 1039 1040 1041 1042 1043 1044
					struct request *, unsigned int),
				    void *data)
{
	unsigned int i;

	for (i = 0; i < hctx->queue_depth; i++) {
		struct request *rq = hctx->rqs[i];

1045
		free(data, hctx, rq, i);
1046 1047 1048
	}
}

1049 1050
void blk_mq_free_commands(struct request_queue *q,
			  void (*free)(void *, struct blk_mq_hw_ctx *,
1051 1052 1053 1054 1055 1056 1057
					struct request *, unsigned int),
			  void *data)
{
	struct blk_mq_hw_ctx *hctx;
	unsigned int i;

	queue_for_each_hw_ctx(q, hctx, i)
1058
		blk_mq_free_hw_commands(hctx, free, data);
1059
}
1060
EXPORT_SYMBOL(blk_mq_free_commands);
1061 1062 1063 1064 1065 1066

static void blk_mq_free_rq_map(struct blk_mq_hw_ctx *hctx)
{
	struct page *page;

	while (!list_empty(&hctx->page_list)) {
1067 1068
		page = list_first_entry(&hctx->page_list, struct page, lru);
		list_del_init(&page->lru);
1069 1070 1071 1072 1073 1074 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
		__free_pages(page, page->private);
	}

	kfree(hctx->rqs);

	if (hctx->tags)
		blk_mq_free_tags(hctx->tags);
}

static size_t order_to_size(unsigned int order)
{
	size_t ret = PAGE_SIZE;

	while (order--)
		ret *= 2;

	return ret;
}

static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
			      unsigned int reserved_tags, int node)
{
	unsigned int i, j, entries_per_page, max_order = 4;
	size_t rq_size, left;

	INIT_LIST_HEAD(&hctx->page_list);

	hctx->rqs = kmalloc_node(hctx->queue_depth * sizeof(struct request *),
					GFP_KERNEL, node);
	if (!hctx->rqs)
		return -ENOMEM;

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

	for (i = 0; i < hctx->queue_depth;) {
		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 {
			page = alloc_pages_node(node, GFP_KERNEL, this_order);
			if (page)
				break;
			if (!this_order--)
				break;
			if (order_to_size(this_order) < rq_size)
				break;
		} while (1);

		if (!page)
			break;

		page->private = this_order;
1132
		list_add_tail(&page->lru, &hctx->page_list);
1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 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 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 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 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352

		p = page_address(page);
		entries_per_page = order_to_size(this_order) / rq_size;
		to_do = min(entries_per_page, hctx->queue_depth - i);
		left -= to_do * rq_size;
		for (j = 0; j < to_do; j++) {
			hctx->rqs[i] = p;
			blk_mq_rq_init(hctx, hctx->rqs[i]);
			p += rq_size;
			i++;
		}
	}

	if (i < (reserved_tags + BLK_MQ_TAG_MIN))
		goto err_rq_map;
	else if (i != hctx->queue_depth) {
		hctx->queue_depth = i;
		pr_warn("%s: queue depth set to %u because of low memory\n",
					__func__, i);
	}

	hctx->tags = blk_mq_init_tags(hctx->queue_depth, reserved_tags, node);
	if (!hctx->tags) {
err_rq_map:
		blk_mq_free_rq_map(hctx);
		return -ENOMEM;
	}

	return 0;
}

static int blk_mq_init_hw_queues(struct request_queue *q,
				 struct blk_mq_reg *reg, void *driver_data)
{
	struct blk_mq_hw_ctx *hctx;
	unsigned int i, j;

	/*
	 * Initialize hardware queues
	 */
	queue_for_each_hw_ctx(q, hctx, i) {
		unsigned int num_maps;
		int node;

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

		INIT_DELAYED_WORK(&hctx->delayed_work, blk_mq_work_fn);
		spin_lock_init(&hctx->lock);
		INIT_LIST_HEAD(&hctx->dispatch);
		hctx->queue = q;
		hctx->queue_num = i;
		hctx->flags = reg->flags;
		hctx->queue_depth = reg->queue_depth;
		hctx->cmd_size = reg->cmd_size;

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

		if (blk_mq_init_rq_map(hctx, reg->reserved_tags, node))
			break;

		/*
		 * Allocate space for all possible cpus to avoid allocation in
		 * runtime
		 */
		hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
						GFP_KERNEL, node);
		if (!hctx->ctxs)
			break;

		num_maps = ALIGN(nr_cpu_ids, BITS_PER_LONG) / BITS_PER_LONG;
		hctx->ctx_map = kzalloc_node(num_maps * sizeof(unsigned long),
						GFP_KERNEL, node);
		if (!hctx->ctx_map)
			break;

		hctx->nr_ctx_map = num_maps;
		hctx->nr_ctx = 0;

		if (reg->ops->init_hctx &&
		    reg->ops->init_hctx(hctx, driver_data, i))
			break;
	}

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

	/*
	 * Init failed
	 */
	queue_for_each_hw_ctx(q, hctx, j) {
		if (i == j)
			break;

		if (reg->ops->exit_hctx)
			reg->ops->exit_hctx(hctx, j);

		blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
		blk_mq_free_rq_map(hctx);
		kfree(hctx->ctxs);
	}

	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 */
		hctx = q->mq_ops->map_queue(q, i);
		hctx->nr_ctx++;

		if (!cpu_online(i))
			continue;

		/*
		 * 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) {
		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 */
		hctx = q->mq_ops->map_queue(q, i);
		ctx->index_hw = hctx->nr_ctx;
		hctx->ctxs[hctx->nr_ctx++] = ctx;
	}
}

struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
					void *driver_data)
{
	struct blk_mq_hw_ctx **hctxs;
	struct blk_mq_ctx *ctx;
	struct request_queue *q;
	int i;

	if (!reg->nr_hw_queues ||
	    !reg->ops->queue_rq || !reg->ops->map_queue ||
	    !reg->ops->alloc_hctx || !reg->ops->free_hctx)
		return ERR_PTR(-EINVAL);

	if (!reg->queue_depth)
		reg->queue_depth = BLK_MQ_MAX_DEPTH;
	else if (reg->queue_depth > BLK_MQ_MAX_DEPTH) {
		pr_err("blk-mq: queuedepth too large (%u)\n", reg->queue_depth);
		reg->queue_depth = BLK_MQ_MAX_DEPTH;
	}

	if (reg->queue_depth < (reg->reserved_tags + BLK_MQ_TAG_MIN))
		return ERR_PTR(-EINVAL);

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

	hctxs = kmalloc_node(reg->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
			reg->numa_node);

	if (!hctxs)
		goto err_percpu;

	for (i = 0; i < reg->nr_hw_queues; i++) {
		hctxs[i] = reg->ops->alloc_hctx(reg, i);
		if (!hctxs[i])
			goto err_hctxs;

		hctxs[i]->numa_node = NUMA_NO_NODE;
		hctxs[i]->queue_num = i;
	}

	q = blk_alloc_queue_node(GFP_KERNEL, reg->numa_node);
	if (!q)
		goto err_hctxs;

	q->mq_map = blk_mq_make_queue_map(reg);
	if (!q->mq_map)
		goto err_map;

	setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
	blk_queue_rq_timeout(q, 30000);

	q->nr_queues = nr_cpu_ids;
	q->nr_hw_queues = reg->nr_hw_queues;

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

	q->mq_ops = reg->ops;
1353
	q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
1354

1355 1356
	q->sg_reserved_size = INT_MAX;

1357 1358 1359 1360 1361
	blk_queue_make_request(q, blk_mq_make_request);
	blk_queue_rq_timed_out(q, reg->ops->timeout);
	if (reg->timeout)
		blk_queue_rq_timeout(q, reg->timeout);

1362 1363 1364
	if (reg->ops->complete)
		blk_queue_softirq_done(q, reg->ops->complete);

1365 1366 1367
	blk_mq_init_flush(q);
	blk_mq_init_cpu_queues(q, reg->nr_hw_queues);

1368 1369 1370
	q->flush_rq = kzalloc(round_up(sizeof(struct request) + reg->cmd_size,
				cache_line_size()), GFP_KERNEL);
	if (!q->flush_rq)
1371 1372
		goto err_hw;

1373 1374 1375
	if (blk_mq_init_hw_queues(q, reg, driver_data))
		goto err_flush_rq;

1376 1377 1378 1379 1380 1381 1382
	blk_mq_map_swqueue(q);

	mutex_lock(&all_q_mutex);
	list_add_tail(&q->all_q_node, &all_q_list);
	mutex_unlock(&all_q_mutex);

	return q;
1383 1384 1385

err_flush_rq:
	kfree(q->flush_rq);
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err_hw:
	kfree(q->mq_map);
err_map:
	blk_cleanup_queue(q);
err_hctxs:
	for (i = 0; i < reg->nr_hw_queues; i++) {
		if (!hctxs[i])
			break;
		reg->ops->free_hctx(hctxs[i], i);
	}
	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)
{
	struct blk_mq_hw_ctx *hctx;
	int i;

	queue_for_each_hw_ctx(q, hctx, i) {
		kfree(hctx->ctx_map);
		kfree(hctx->ctxs);
		blk_mq_free_rq_map(hctx);
		blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
		if (q->mq_ops->exit_hctx)
			q->mq_ops->exit_hctx(hctx, i);
		q->mq_ops->free_hctx(hctx, i);
	}

	free_percpu(q->queue_ctx);
	kfree(q->queue_hw_ctx);
	kfree(q->mq_map);

	q->queue_ctx = NULL;
	q->queue_hw_ctx = NULL;
	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 */
1432
static void blk_mq_queue_reinit(struct request_queue *q)
1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448
{
	blk_mq_freeze_queue(q);

	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);

	blk_mq_unfreeze_queue(q);
}

1449 1450
static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
				      unsigned long action, void *hcpu)
1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470
{
	struct request_queue *q;

	/*
	 * Before new mapping is 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 queue below to get
	 * optimal settings.
	 */
	if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
	    action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
		return NOTIFY_OK;

	mutex_lock(&all_q_mutex);
	list_for_each_entry(q, &all_q_list, all_q_node)
		blk_mq_queue_reinit(q);
	mutex_unlock(&all_q_mutex);
	return NOTIFY_OK;
}

1471 1472 1473 1474 1475 1476 1477 1478 1479 1480
void blk_mq_disable_hotplug(void)
{
	mutex_lock(&all_q_mutex);
}

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

1481 1482 1483 1484 1485 1486 1487 1488 1489 1490
static int __init blk_mq_init(void)
{
	blk_mq_cpu_init();

	/* Must be called after percpu_counter_hotcpu_callback() */
	hotcpu_notifier(blk_mq_queue_reinit_notify, -10);

	return 0;
}
subsys_initcall(blk_mq_init);