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Commit 7c94e1c1 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
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block: introduce blk_flush_queue to drive flush machinery 



This patch introduces 'struct blk_flush_queue' and puts all
flush machinery related fields into this structure, so that

	- flush implementation details aren't exposed to driver
	- it is easy to convert to per dispatch-queue flush machinery

This patch is basically a mechanical replacement.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 7ddab5de

block/blk-core.c

+3 −1
Original line number Diff line number Diff line
@@ -390,11 +390,13 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all) 
		 * be drained.  Check all the queues and counters.

		 */

		if (drain_all) {

			struct blk_flush_queue *fq = blk_get_flush_queue(q);

			drain |= !list_empty(&q->queue_head);

			for (i = 0; i < 2; i++) {

				drain |= q->nr_rqs[i];

				drain |= q->in_flight[i];

				drain |= !list_empty(&q->flush_queue[i]);

				if (fq)

				    drain |= !list_empty(&fq->flush_queue[i]);

			}

		}

block/blk-flush.c

+68 −41
Original line number Diff line number Diff line
@@ -28,7 +28,7 @@ 
 *

 * The actual execution of flush is double buffered.  Whenever a request

 * needs to execute PRE or POSTFLUSH, it queues at

 * q->flush_queue[q->flush_pending_idx].  Once certain criteria are met, a

 * fq->flush_queue[fq->flush_pending_idx].  Once certain criteria are met, a

 * flush is issued and the pending_idx is toggled.  When the flush

 * completes, all the requests which were pending are proceeded to the next

 * step.  This allows arbitrary merging of different types of FLUSH/FUA
@@ -155,7 +155,7 @@ static bool blk_flush_queue_rq(struct request *rq, bool add_front) 
 * completion and trigger the next step.

 *

 * CONTEXT:

 * spin_lock_irq(q->queue_lock or q->mq_flush_lock)

 * spin_lock_irq(q->queue_lock or fq->mq_flush_lock)

 *

 * RETURNS:

 * %true if requests were added to the dispatch queue, %false otherwise.
@@ -164,7 +164,8 @@ static bool blk_flush_complete_seq(struct request *rq, unsigned int seq, 
				   int error)

{

	struct request_queue *q = rq->q;

	struct list_head *pending = &q->flush_queue[q->flush_pending_idx];

	struct blk_flush_queue *fq = blk_get_flush_queue(q);

	struct list_head *pending = &fq->flush_queue[fq->flush_pending_idx];

	bool queued = false, kicked;



	BUG_ON(rq->flush.seq & seq);
@@ -180,12 +181,12 @@ static bool blk_flush_complete_seq(struct request *rq, unsigned int seq, 
	case REQ_FSEQ_POSTFLUSH:

		/* queue for flush */

		if (list_empty(pending))

			q->flush_pending_since = jiffies;

			fq->flush_pending_since = jiffies;

		list_move_tail(&rq->flush.list, pending);

		break;



	case REQ_FSEQ_DATA:

		list_move_tail(&rq->flush.list, &q->flush_data_in_flight);

		list_move_tail(&rq->flush.list, &fq->flush_data_in_flight);

		queued = blk_flush_queue_rq(rq, true);

		break;
@@ -220,17 +221,18 @@ static void flush_end_io(struct request *flush_rq, int error) 
	bool queued = false;

	struct request *rq, *n;

	unsigned long flags = 0;

	struct blk_flush_queue *fq = blk_get_flush_queue(q);



	if (q->mq_ops) {

		spin_lock_irqsave(&q->mq_flush_lock, flags);

		spin_lock_irqsave(&fq->mq_flush_lock, flags);

		flush_rq->tag = -1;

	}



	running = &q->flush_queue[q->flush_running_idx];

	BUG_ON(q->flush_pending_idx == q->flush_running_idx);

	running = &fq->flush_queue[fq->flush_running_idx];

	BUG_ON(fq->flush_pending_idx == fq->flush_running_idx);



	/* account completion of the flush request */

	q->flush_running_idx ^= 1;

	fq->flush_running_idx ^= 1;



	if (!q->mq_ops)

		elv_completed_request(q, flush_rq);
@@ -254,13 +256,13 @@ static void flush_end_io(struct request *flush_rq, int error) 
	 * directly into request_fn may confuse the driver.  Always use

	 * kblockd.

	 */

	if (queued || q->flush_queue_delayed) {

	if (queued || fq->flush_queue_delayed) {

		WARN_ON(q->mq_ops);

		blk_run_queue_async(q);

	}

	q->flush_queue_delayed = 0;

	fq->flush_queue_delayed = 0;

	if (q->mq_ops)

		spin_unlock_irqrestore(&q->mq_flush_lock, flags);

		spin_unlock_irqrestore(&fq->mq_flush_lock, flags);

}



/**
@@ -271,33 +273,34 @@ static void flush_end_io(struct request *flush_rq, int error) 
 * Please read the comment at the top of this file for more info.

 *

 * CONTEXT:

 * spin_lock_irq(q->queue_lock or q->mq_flush_lock)

 * spin_lock_irq(q->queue_lock or fq->mq_flush_lock)

 *

 * RETURNS:

 * %true if flush was issued, %false otherwise.

 */

static bool blk_kick_flush(struct request_queue *q)

{

	struct list_head *pending = &q->flush_queue[q->flush_pending_idx];

	struct blk_flush_queue *fq = blk_get_flush_queue(q);

	struct list_head *pending = &fq->flush_queue[fq->flush_pending_idx];

	struct request *first_rq =

		list_first_entry(pending, struct request, flush.list);

	struct request *flush_rq = q->flush_rq;

	struct request *flush_rq = fq->flush_rq;



	/* C1 described at the top of this file */

	if (q->flush_pending_idx != q->flush_running_idx || list_empty(pending))

	if (fq->flush_pending_idx != fq->flush_running_idx || list_empty(pending))

		return false;



	/* C2 and C3 */

	if (!list_empty(&q->flush_data_in_flight) &&

	if (!list_empty(&fq->flush_data_in_flight) &&

	    time_before(jiffies,

			q->flush_pending_since + FLUSH_PENDING_TIMEOUT))

			fq->flush_pending_since + FLUSH_PENDING_TIMEOUT))

		return false;



	/*

	 * Issue flush and toggle pending_idx.  This makes pending_idx

	 * different from running_idx, which means flush is in flight.

	 */

	q->flush_pending_idx ^= 1;

	fq->flush_pending_idx ^= 1;



	blk_rq_init(q, flush_rq);

	if (q->mq_ops)
@@ -329,6 +332,7 @@ static void mq_flush_data_end_io(struct request *rq, int error) 
	struct blk_mq_hw_ctx *hctx;

	struct blk_mq_ctx *ctx;

	unsigned long flags;

	struct blk_flush_queue *fq = blk_get_flush_queue(q);



	ctx = rq->mq_ctx;

	hctx = q->mq_ops->map_queue(q, ctx->cpu);
@@ -337,10 +341,10 @@ static void mq_flush_data_end_io(struct request *rq, int error) 
	 * After populating an empty queue, kick it to avoid stall.  Read

	 * the comment in flush_end_io().

	 */

	spin_lock_irqsave(&q->mq_flush_lock, flags);

	spin_lock_irqsave(&fq->mq_flush_lock, flags);

	if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error))

		blk_mq_run_hw_queue(hctx, true);

	spin_unlock_irqrestore(&q->mq_flush_lock, flags);

	spin_unlock_irqrestore(&fq->mq_flush_lock, flags);

}



/**
@@ -408,11 +412,13 @@ void blk_insert_flush(struct request *rq) 
	rq->cmd_flags |= REQ_FLUSH_SEQ;

	rq->flush.saved_end_io = rq->end_io; /* Usually NULL */

	if (q->mq_ops) {

		struct blk_flush_queue *fq = blk_get_flush_queue(q);



		rq->end_io = mq_flush_data_end_io;



		spin_lock_irq(&q->mq_flush_lock);

		spin_lock_irq(&fq->mq_flush_lock);

		blk_flush_complete_seq(rq, REQ_FSEQ_ACTIONS & ~policy, 0);

		spin_unlock_irq(&q->mq_flush_lock);

		spin_unlock_irq(&fq->mq_flush_lock);

		return;

	}

	rq->end_io = flush_data_end_io;
@@ -473,31 +479,52 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, 
}

EXPORT_SYMBOL(blkdev_issue_flush);



static int blk_mq_init_flush(struct request_queue *q)

static struct blk_flush_queue *blk_alloc_flush_queue(

		struct request_queue *q)

{

	struct blk_mq_tag_set *set = q->tag_set;

	struct blk_flush_queue *fq;

	int rq_sz = sizeof(struct request);



	spin_lock_init(&q->mq_flush_lock);

	fq = kzalloc(sizeof(*fq), GFP_KERNEL);

	if (!fq)

		goto fail;



	q->flush_rq = kzalloc(round_up(sizeof(struct request) +

				set->cmd_size, cache_line_size()),

				GFP_KERNEL);

	if (!q->flush_rq)

		return -ENOMEM;

	return 0;

	if (q->mq_ops) {

		spin_lock_init(&fq->mq_flush_lock);

		rq_sz = round_up(rq_sz + q->tag_set->cmd_size,

				cache_line_size());

	}



int blk_init_flush(struct request_queue *q)

	fq->flush_rq = kzalloc(rq_sz, GFP_KERNEL);

	if (!fq->flush_rq)

		goto fail_rq;



	INIT_LIST_HEAD(&fq->flush_queue[0]);

	INIT_LIST_HEAD(&fq->flush_queue[1]);

	INIT_LIST_HEAD(&fq->flush_data_in_flight);



	return fq;



 fail_rq:

	kfree(fq);

 fail:

	return NULL;

}



static void blk_free_flush_queue(struct blk_flush_queue *fq)

{

	INIT_LIST_HEAD(&q->flush_queue[0]);

	INIT_LIST_HEAD(&q->flush_queue[1]);

	INIT_LIST_HEAD(&q->flush_data_in_flight);

	/* bio based request queue hasn't flush queue */

	if (!fq)

		return;



	if (q->mq_ops)

		return blk_mq_init_flush(q);

	kfree(fq->flush_rq);

	kfree(fq);

}



	q->flush_rq = kzalloc(sizeof(struct request), GFP_KERNEL);

	if (!q->flush_rq)

int blk_init_flush(struct request_queue *q)

{

	q->fq = blk_alloc_flush_queue(q);

	if (!q->fq)

		return -ENOMEM;



	return 0;
@@ -505,5 +532,5 @@ int blk_init_flush(struct request_queue *q) 


void blk_exit_flush(struct request_queue *q)

{

	kfree(q->flush_rq);

	blk_free_flush_queue(q->fq);

}

block/blk-mq.c

+6 −4
Original line number Diff line number Diff line
@@ -508,20 +508,22 @@ void blk_mq_kick_requeue_list(struct request_queue *q) 
}

EXPORT_SYMBOL(blk_mq_kick_requeue_list);



static inline bool is_flush_request(struct request *rq, unsigned int tag)

static inline bool is_flush_request(struct request *rq,

		struct blk_flush_queue *fq, unsigned int tag)

{

	return ((rq->cmd_flags & REQ_FLUSH_SEQ) &&

			rq->q->flush_rq->tag == tag);

			fq->flush_rq->tag == tag);

}



struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)

{

	struct request *rq = tags->rqs[tag];

	struct blk_flush_queue *fq = blk_get_flush_queue(rq->q);



	if (!is_flush_request(rq, tag))

	if (!is_flush_request(rq, fq, tag))

		return rq;



	return rq->q->flush_rq;

	return fq->flush_rq;

}

EXPORT_SYMBOL(blk_mq_tag_to_rq);

block/blk.h

+20 −2
Original line number Diff line number Diff line
@@ -12,11 +12,28 @@ 
/* Max future timer expiry for timeouts */

#define BLK_MAX_TIMEOUT		(5 * HZ)



struct blk_flush_queue {

	unsigned int		flush_queue_delayed:1;

	unsigned int		flush_pending_idx:1;

	unsigned int		flush_running_idx:1;

	unsigned long		flush_pending_since;

	struct list_head	flush_queue[2];

	struct list_head	flush_data_in_flight;

	struct request		*flush_rq;

	spinlock_t		mq_flush_lock;

};



extern struct kmem_cache *blk_requestq_cachep;

extern struct kmem_cache *request_cachep;

extern struct kobj_type blk_queue_ktype;

extern struct ida blk_queue_ida;



static inline struct blk_flush_queue *blk_get_flush_queue(

		struct request_queue *q)

{

	return q->fq;

}



static inline void __blk_get_queue(struct request_queue *q)

{

	kobject_get(&q->kobj);
@@ -89,6 +106,7 @@ void blk_insert_flush(struct request *rq); 
static inline struct request *__elv_next_request(struct request_queue *q)

{

	struct request *rq;

	struct blk_flush_queue *fq = blk_get_flush_queue(q);



	while (1) {

		if (!list_empty(&q->queue_head)) {
@@ -111,9 +129,9 @@ static inline struct request *__elv_next_request(struct request_queue *q) 
		 * should be restarted later. Please see flush_end_io() for

		 * details.

		 */

		if (q->flush_pending_idx != q->flush_running_idx &&

		if (fq->flush_pending_idx != fq->flush_running_idx &&

				!queue_flush_queueable(q)) {

			q->flush_queue_delayed = 1;

			fq->flush_queue_delayed = 1;

			return NULL;

		}

		if (unlikely(blk_queue_bypass(q)) ||

include/linux/blkdev.h

+2 −8
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ struct request; 
struct sg_io_hdr;

struct bsg_job;

struct blkcg_gq;

struct blk_flush_queue;



#define BLKDEV_MIN_RQ	4

#define BLKDEV_MAX_RQ	128	/* Default maximum */
@@ -455,14 +456,7 @@ struct request_queue { 
	 */

	unsigned int		flush_flags;

	unsigned int		flush_not_queueable:1;

	unsigned int		flush_queue_delayed:1;

	unsigned int		flush_pending_idx:1;

	unsigned int		flush_running_idx:1;

	unsigned long		flush_pending_since;

	struct list_head	flush_queue[2];

	struct list_head	flush_data_in_flight;

	struct request		*flush_rq;

	spinlock_t		mq_flush_lock;

	struct blk_flush_queue	*fq;



	struct list_head	requeue_list;

	spinlock_t		requeue_lock;