blk-mq.c 35.4 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) {
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		rq = hctx->tags->rqs[tag];
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		blk_rq_init(hctx->queue, rq);
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		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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		if (gfp & __GFP_WAIT) {
			__blk_mq_run_hw_queue(hctx);
			blk_mq_put_ctx(ctx);
		} else {
			blk_mq_put_ctx(ctx);
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			break;
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		}
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		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);

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_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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/*
 * Clone all relevant state from a request that has been put on hold in
 * the flush state machine into the preallocated flush request that hangs
 * off the request queue.
 *
 * For a driver the flush request should be invisible, that's why we are
 * impersonating the original request here.
 */
void blk_mq_clone_flush_request(struct request *flush_rq,
		struct request *orig_rq)
{
	struct blk_mq_hw_ctx *hctx =
		orig_rq->q->mq_ops->map_queue(orig_rq->q, orig_rq->mq_ctx->cpu);

	flush_rq->mq_ctx = orig_rq->mq_ctx;
	flush_rq->tag = orig_rq->tag;
	memcpy(blk_mq_rq_to_pdu(flush_rq), blk_mq_rq_to_pdu(orig_rq),
		hctx->cmd_size);
}

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inline void __blk_mq_end_io(struct request *rq, int error)
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{
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	blk_account_io_done(rq);

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	if (rq->end_io) {
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		rq->end_io(rq, error);
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	} else {
		if (unlikely(blk_bidi_rq(rq)))
			blk_mq_free_request(rq->next_rq);
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		blk_mq_free_request(rq);
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	}
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}
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EXPORT_SYMBOL(__blk_mq_end_io);

void blk_mq_end_io(struct request *rq, int error)
{
	if (blk_update_request(rq, error, blk_rq_bytes(rq)))
		BUG();
	__blk_mq_end_io(rq, error);
}
EXPORT_SYMBOL(blk_mq_end_io);
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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);

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	rq->resid_len = blk_rq_bytes(rq);
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	if (unlikely(blk_bidi_rq(rq)))
		rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
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	/*
	 * 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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}

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struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
{
	return tags->rqs[tag];
}
EXPORT_SYMBOL(blk_mq_tag_to_rq);

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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;

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

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		rq = blk_mq_tag_to_rq(hctx->tags, tag++);
		if (rq->q != hctx->queue)
			continue;
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		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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	WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask));
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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;

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	if (!async && cpumask_test_cpu(smp_processor_id(), hctx->cpumask))
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		__blk_mq_run_hw_queue(hctx);
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	else if (hctx->queue->nr_hw_queues == 1)
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		kblockd_schedule_delayed_work(&hctx->run_work, 0);
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	else {
		unsigned int cpu;

		/*
		 * It'd be great if the workqueue API had a way to pass
		 * in a mask and had some smarts for more clever placement
		 * than the first CPU. Or we could round-robin here. For now,
		 * just queue on the first CPU.
		 */
		cpu = cpumask_first(hctx->cpumask);
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		kblockd_schedule_delayed_work_on(cpu, &hctx->run_work, 0);
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	}
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}

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;

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

void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
678 679
	cancel_delayed_work(&hctx->run_work);
	cancel_delayed_work(&hctx->delay_work);
680 681 682 683
	set_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queue);

684 685 686 687 688 689 690 691 692 693
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);

694 695 696
void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
{
	clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
697 698

	preempt_disable();
699
	__blk_mq_run_hw_queue(hctx);
700
	preempt_enable();
701 702 703
}
EXPORT_SYMBOL(blk_mq_start_hw_queue);

704
void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
705 706 707 708 709 710 711 712 713
{
	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);
714
		preempt_disable();
715
		blk_mq_run_hw_queue(hctx, async);
716
		preempt_enable();
717 718 719 720
	}
}
EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);

721
static void blk_mq_run_work_fn(struct work_struct *work)
722 723 724
{
	struct blk_mq_hw_ctx *hctx;

725
	hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
726

727 728 729
	__blk_mq_run_hw_queue(hctx);
}

730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760
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)
{
	unsigned long tmo = msecs_to_jiffies(msecs);

	if (hctx->queue->nr_hw_queues == 1)
		kblockd_schedule_delayed_work(&hctx->delay_work, tmo);
	else {
		unsigned int cpu;

		/*
		 * It'd be great if the workqueue API had a way to pass
		 * in a mask and had some smarts for more clever placement
		 * than the first CPU. Or we could round-robin here. For now,
		 * just queue on the first CPU.
		 */
		cpu = cpumask_first(hctx->cpumask);
		kblockd_schedule_delayed_work_on(cpu, &hctx->delay_work, tmo);
	}
}
EXPORT_SYMBOL(blk_mq_delay_queue);

761
static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
762
				    struct request *rq, bool at_head)
763 764 765
{
	struct blk_mq_ctx *ctx = rq->mq_ctx;

766 767
	trace_block_rq_insert(hctx->queue, rq);

768 769 770 771
	if (at_head)
		list_add(&rq->queuelist, &ctx->rq_list);
	else
		list_add_tail(&rq->queuelist, &ctx->rq_list);
772 773 774 775 776 777 778 779
	blk_mq_hctx_mark_pending(hctx, ctx);

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

780 781
void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
		bool async)
782
{
783
	struct request_queue *q = rq->q;
784
	struct blk_mq_hw_ctx *hctx;
785 786 787 788 789
	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;
790 791 792

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

793 794
	if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA) &&
	    !(rq->cmd_flags & (REQ_FLUSH_SEQ))) {
795 796 797
		blk_insert_flush(rq);
	} else {
		spin_lock(&ctx->lock);
798
		__blk_mq_insert_request(hctx, rq, at_head);
799 800 801 802 803
		spin_unlock(&ctx->lock);
	}

	if (run_queue)
		blk_mq_run_hw_queue(hctx, async);
804 805

	blk_mq_put_ctx(current_ctx);
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
}

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;
837
		__blk_mq_insert_request(hctx, rq, false);
838 839 840 841
	}
	spin_unlock(&ctx->lock);

	blk_mq_run_hw_queue(hctx, from_schedule);
842
	blk_mq_put_ctx(current_ctx);
843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925
}

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);

926 927 928 929 930
	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
		bio_endio(bio, -EIO);
		return;
	}

931 932 933 934 935 936 937 938 939 940 941
	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);

S
Shaohua Li 已提交
942 943
	if (is_sync)
		rw |= REQ_SYNC;
944
	trace_block_getrq(q, bio, rw);
945
	rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false);
946
	if (likely(rq))
947
		blk_mq_rq_ctx_init(q, ctx, rq, rw);
948 949 950
	else {
		blk_mq_put_ctx(ctx);
		trace_block_sleeprq(q, bio, rw);
951 952
		rq = blk_mq_alloc_request_pinned(q, rw, __GFP_WAIT|GFP_ATOMIC,
							false);
953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974
		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_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
975
			if (list_empty(&plug->mq_list))
976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993
				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);
994
		__blk_mq_insert_request(hctx, rq, false);
995 996 997 998 999 1000 1001 1002 1003 1004 1005
	}

	spin_unlock(&ctx->lock);

	/*
	 * 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);
1006
	blk_mq_put_ctx(ctx);
1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017
}

/*
 * 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);

1018
struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_tag_set *set,
1019 1020 1021
						   unsigned int hctx_index)
{
	return kmalloc_node(sizeof(struct blk_mq_hw_ctx),
1022
				GFP_KERNEL | __GFP_ZERO, set->numa_node);
1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036
}
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;
1037
	struct request_queue *q = hctx->queue;
1038 1039 1040 1041 1042 1043 1044 1045 1046
	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.
	 */
1047
	ctx = __blk_mq_get_ctx(q, cpu);
1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058

	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;

1059
	ctx = blk_mq_get_ctx(q);
1060 1061 1062 1063 1064 1065 1066 1067 1068 1069
	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);
	}

1070
	hctx = q->mq_ops->map_queue(q, ctx->cpu);
1071 1072 1073
	blk_mq_hctx_mark_pending(hctx, ctx);

	spin_unlock(&ctx->lock);
1074 1075

	blk_mq_run_hw_queue(hctx, true);
1076
	blk_mq_put_ctx(ctx);
1077 1078
}

1079 1080
static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
		struct blk_mq_tags *tags, unsigned int hctx_idx)
1081
{
1082
	struct page *page;
1083

1084
	if (tags->rqs && set->ops->exit_request) {
1085
		int i;
1086

1087 1088
		for (i = 0; i < tags->nr_tags; i++) {
			if (!tags->rqs[i])
1089
				continue;
1090 1091
			set->ops->exit_request(set->driver_data, tags->rqs[i],
						hctx_idx, i);
1092
		}
1093 1094
	}

1095 1096
	while (!list_empty(&tags->page_list)) {
		page = list_first_entry(&tags->page_list, struct page, lru);
1097
		list_del_init(&page->lru);
1098 1099 1100
		__free_pages(page, page->private);
	}

1101
	kfree(tags->rqs);
1102

1103
	blk_mq_free_tags(tags);
1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115
}

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

	while (order--)
		ret *= 2;

	return ret;
}

1116 1117
static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
		unsigned int hctx_idx)
1118
{
1119
	struct blk_mq_tags *tags;
1120 1121 1122
	unsigned int i, j, entries_per_page, max_order = 4;
	size_t rq_size, left;

1123 1124 1125 1126
	tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
				set->numa_node);
	if (!tags)
		return NULL;
1127

1128 1129 1130 1131 1132 1133 1134 1135
	INIT_LIST_HEAD(&tags->page_list);

	tags->rqs = kmalloc_node(set->queue_depth * sizeof(struct request *),
					GFP_KERNEL, set->numa_node);
	if (!tags->rqs) {
		blk_mq_free_tags(tags);
		return NULL;
	}
1136 1137 1138 1139 1140

	/*
	 * rq_size is the size of the request plus driver payload, rounded
	 * to the cacheline size
	 */
1141
	rq_size = round_up(sizeof(struct request) + set->cmd_size,
1142
				cache_line_size());
1143
	left = rq_size * set->queue_depth;
1144

1145
	for (i = 0; i < set->queue_depth; ) {
1146 1147 1148 1149 1150 1151 1152 1153 1154
		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 {
1155 1156
			page = alloc_pages_node(set->numa_node, GFP_KERNEL,
						this_order);
1157 1158 1159 1160 1161 1162 1163 1164 1165
			if (page)
				break;
			if (!this_order--)
				break;
			if (order_to_size(this_order) < rq_size)
				break;
		} while (1);

		if (!page)
1166
			goto fail;
1167 1168

		page->private = this_order;
1169
		list_add_tail(&page->lru, &tags->page_list);
1170 1171 1172

		p = page_address(page);
		entries_per_page = order_to_size(this_order) / rq_size;
1173
		to_do = min(entries_per_page, set->queue_depth - i);
1174 1175
		left -= to_do * rq_size;
		for (j = 0; j < to_do; j++) {
1176 1177 1178 1179 1180 1181
			tags->rqs[i] = p;
			if (set->ops->init_request) {
				if (set->ops->init_request(set->driver_data,
						tags->rqs[i], hctx_idx, i,
						set->numa_node))
					goto fail;
1182 1183
			}

1184 1185 1186 1187 1188
			p += rq_size;
			i++;
		}
	}

1189
	return tags;
1190

1191 1192 1193 1194
fail:
	pr_warn("%s: failed to allocate requests\n", __func__);
	blk_mq_free_rq_map(set, tags, hctx_idx);
	return NULL;
1195 1196 1197
}

static int blk_mq_init_hw_queues(struct request_queue *q,
1198
		struct blk_mq_tag_set *set)
1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211
{
	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)
1212
			node = hctx->numa_node = set->numa_node;
1213

1214 1215
		INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
		INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1216 1217 1218 1219
		spin_lock_init(&hctx->lock);
		INIT_LIST_HEAD(&hctx->dispatch);
		hctx->queue = q;
		hctx->queue_num = i;
1220 1221
		hctx->flags = set->flags;
		hctx->cmd_size = set->cmd_size;
1222 1223 1224 1225 1226

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

1227
		hctx->tags = set->tags[i];
1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246

		/*
		 * 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;

1247 1248
		if (set->ops->init_hctx &&
		    set->ops->init_hctx(hctx, set->driver_data, i))
1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261
			break;
	}

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

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

1262 1263
		if (set->ops->exit_hctx)
			set->ops->exit_hctx(hctx, j);
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

		blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
		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 */
		if (!cpu_online(i))
			continue;

1291 1292 1293 1294
		hctx = q->mq_ops->map_queue(q, i);
		cpumask_set_cpu(i, hctx->cpumask);
		hctx->nr_ctx++;

1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310
		/*
		 * 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) {
1311
		cpumask_clear(hctx->cpumask);
1312 1313 1314 1315 1316 1317 1318 1319
		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 */
1320 1321 1322
		if (!cpu_online(i))
			continue;

1323
		hctx = q->mq_ops->map_queue(q, i);
1324
		cpumask_set_cpu(i, hctx->cpumask);
1325 1326 1327 1328 1329
		ctx->index_hw = hctx->nr_ctx;
		hctx->ctxs[hctx->nr_ctx++] = ctx;
	}
}

1330
struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
1331 1332 1333 1334 1335 1336 1337 1338 1339 1340
{
	struct blk_mq_hw_ctx **hctxs;
	struct blk_mq_ctx *ctx;
	struct request_queue *q;
	int i;

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

1341 1342
	hctxs = kmalloc_node(set->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
			set->numa_node);
1343 1344 1345 1346

	if (!hctxs)
		goto err_percpu;

1347 1348
	for (i = 0; i < set->nr_hw_queues; i++) {
		hctxs[i] = set->ops->alloc_hctx(set, i);
1349 1350 1351
		if (!hctxs[i])
			goto err_hctxs;

1352 1353 1354
		if (!zalloc_cpumask_var(&hctxs[i]->cpumask, GFP_KERNEL))
			goto err_hctxs;

1355 1356 1357 1358
		hctxs[i]->numa_node = NUMA_NO_NODE;
		hctxs[i]->queue_num = i;
	}

1359
	q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
1360 1361 1362
	if (!q)
		goto err_hctxs;

1363
	q->mq_map = blk_mq_make_queue_map(set);
1364 1365 1366 1367 1368 1369 1370
	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;
1371
	q->nr_hw_queues = set->nr_hw_queues;
1372 1373 1374 1375

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

1376
	q->mq_ops = set->ops;
1377
	q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
1378

1379 1380
	q->sg_reserved_size = INT_MAX;

1381
	blk_queue_make_request(q, blk_mq_make_request);
1382 1383 1384
	blk_queue_rq_timed_out(q, set->ops->timeout);
	if (set->timeout)
		blk_queue_rq_timeout(q, set->timeout);
1385

1386 1387
	if (set->ops->complete)
		blk_queue_softirq_done(q, set->ops->complete);
1388

1389
	blk_mq_init_flush(q);
1390
	blk_mq_init_cpu_queues(q, set->nr_hw_queues);
1391

1392 1393 1394
	q->flush_rq = kzalloc(round_up(sizeof(struct request) +
				set->cmd_size, cache_line_size()),
				GFP_KERNEL);
1395
	if (!q->flush_rq)
1396 1397
		goto err_hw;

1398
	if (blk_mq_init_hw_queues(q, set))
1399 1400
		goto err_flush_rq;

1401 1402 1403 1404 1405 1406 1407
	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;
1408 1409 1410

err_flush_rq:
	kfree(q->flush_rq);
1411 1412 1413 1414 1415
err_hw:
	kfree(q->mq_map);
err_map:
	blk_cleanup_queue(q);
err_hctxs:
1416
	for (i = 0; i < set->nr_hw_queues; i++) {
1417 1418
		if (!hctxs[i])
			break;
1419
		free_cpumask_var(hctxs[i]->cpumask);
1420
		set->ops->free_hctx(hctxs[i], i);
1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439
	}
	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_unregister_cpu_notifier(&hctx->cpu_notifier);
		if (q->mq_ops->exit_hctx)
			q->mq_ops->exit_hctx(hctx, i);
1440
		free_cpumask_var(hctx->cpumask);
1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457
		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 */
1458
static void blk_mq_queue_reinit(struct request_queue *q)
1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474
{
	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);
}

1475 1476
static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
				      unsigned long action, void *hcpu)
1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496
{
	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;
}

1497 1498 1499 1500 1501 1502 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 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543
int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
{
	int i;

	if (!set->nr_hw_queues)
		return -EINVAL;
	if (!set->queue_depth || set->queue_depth > BLK_MQ_MAX_DEPTH)
		return -EINVAL;
	if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
		return -EINVAL;

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


	set->tags = kmalloc_node(set->nr_hw_queues * sizeof(struct blk_mq_tags),
				 GFP_KERNEL, set->numa_node);
	if (!set->tags)
		goto out;

	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);
out:
	return -ENOMEM;
}
EXPORT_SYMBOL(blk_mq_alloc_tag_set);

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

	for (i = 0; i < set->nr_hw_queues; i++)
		blk_mq_free_rq_map(set, set->tags[i], i);
}
EXPORT_SYMBOL(blk_mq_free_tag_set);

1544 1545 1546 1547 1548 1549 1550 1551 1552 1553
void blk_mq_disable_hotplug(void)
{
	mutex_lock(&all_q_mutex);
}

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

1554 1555 1556 1557 1558 1559 1560 1561 1562 1563
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);