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Commit b4324fee authored by Kiyoshi Ueda's avatar Kiyoshi Ueda Committed by Alasdair G Kergon
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dm: use md pending for in flight IO counting 



This patch changes the counter for the number of in_flight I/Os
to md->pending from q->in_flight in preparation for a later patch.
No functional change.

Request-based dm used q->in_flight to count the number of in-flight
clones assuming the counter is always incremented for an in-flight
original request and original:clone is 1:1 relationship.
However, it this no longer true for barrier requests.
So use md->pending to count the number of in-flight clones.

Signed-off-by: default avatarKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 9f518b27

drivers/md/dm.c

+18 −28
Original line number Diff line number Diff line
@@ -727,23 +727,16 @@ static void end_clone_bio(struct bio *clone, int error) 
 * the md may be freed in dm_put() at the end of this function.

 * Or do dm_get() before calling this function and dm_put() later.

 */

static void rq_completed(struct mapped_device *md, int run_queue)

static void rq_completed(struct mapped_device *md, int rw, int run_queue)

{

	int wakeup_waiters = 0;

	struct request_queue *q = md->queue;

	unsigned long flags;



	spin_lock_irqsave(q->queue_lock, flags);

	if (!queue_in_flight(q))

		wakeup_waiters = 1;

	spin_unlock_irqrestore(q->queue_lock, flags);

	atomic_dec(&md->pending[rw]);



	/* nudge anyone waiting on suspend queue */

	if (wakeup_waiters)

	if (!md_in_flight(md))

		wake_up(&md->wait);



	if (run_queue)

		blk_run_queue(q);

		blk_run_queue(md->queue);



	/*

	 * dm_put() must be at the end of this function. See the comment above
@@ -774,6 +767,7 @@ static void dm_unprep_request(struct request *rq) 
 */

void dm_requeue_unmapped_request(struct request *clone)

{

	int rw = rq_data_dir(clone);

	struct dm_rq_target_io *tio = clone->end_io_data;

	struct mapped_device *md = tio->md;

	struct request *rq = tio->orig;
@@ -788,7 +782,7 @@ void dm_requeue_unmapped_request(struct request *clone) 
	blk_requeue_request(q, rq);

	spin_unlock_irqrestore(q->queue_lock, flags);



	rq_completed(md, 0);

	rq_completed(md, rw, 0);

}

EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request);
@@ -827,6 +821,7 @@ static void start_queue(struct request_queue *q) 
 */

static void dm_end_request(struct request *clone, int error)

{

	int rw = rq_data_dir(clone);

	struct dm_rq_target_io *tio = clone->end_io_data;

	struct mapped_device *md = tio->md;

	struct request *rq = tio->orig;
@@ -848,7 +843,7 @@ static void dm_end_request(struct request *clone, int error) 


	blk_end_request_all(rq, error);



	rq_completed(md, 1);

	rq_completed(md, rw, 1);

}



/*
@@ -1541,12 +1536,13 @@ static void dm_request_fn(struct request_queue *q) 
	struct mapped_device *md = q->queuedata;

	struct dm_table *map = dm_get_table(md);

	struct dm_target *ti;

	struct request *rq;

	struct request *rq, *clone;



	/*

	 * For suspend, check blk_queue_stopped() and don't increment

	 * the number of in-flight I/Os after the queue is stopped

	 * in dm_suspend().

	 * For suspend, check blk_queue_stopped() and increment

	 * ->pending within a single queue_lock not to increment the

	 * number of in-flight I/Os after the queue is stopped in

	 * dm_suspend().

	 */

	while (!blk_queue_plugged(q) && !blk_queue_stopped(q)) {

		rq = blk_peek_request(q);
@@ -1558,8 +1554,11 @@ static void dm_request_fn(struct request_queue *q) 
			goto plug_and_out;



		blk_start_request(rq);

		clone = rq->special;

		atomic_inc(&md->pending[rq_data_dir(clone)]);



		spin_unlock(q->queue_lock);

		map_request(ti, rq->special, md);

		map_request(ti, clone, md);

		spin_lock_irq(q->queue_lock);

	}
@@ -2071,8 +2070,6 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible) 
{

	int r = 0;

	DECLARE_WAITQUEUE(wait, current);

	struct request_queue *q = md->queue;

	unsigned long flags;



	dm_unplug_all(md->queue);
@@ -2082,14 +2079,7 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible) 
		set_current_state(interruptible);



		smp_mb();

		if (dm_request_based(md)) {

			spin_lock_irqsave(q->queue_lock, flags);

			if (!queue_in_flight(q)) {

				spin_unlock_irqrestore(q->queue_lock, flags);

				break;

			}

			spin_unlock_irqrestore(q->queue_lock, flags);

		} else if (!md_in_flight(md))

		if (!md_in_flight(md))

			break;



		if (interruptible == TASK_INTERRUPTIBLE &&