dm: remove the pending variableNotice: this object is not reachable from any branch.

Remove the "pending" variable and use dm_disk(md)->part0.in_flight.
These variables hold identical values.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Notice: this object is not reachable from any branch.

3 files changed, 22 insertions, 23 deletions

diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index 224d44503a067..0a93f2c83d8a1 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -65,7 +65,6 @@ struct mapped_device {
 	 */
 	struct work_struct work;
 	wait_queue_head_t wait;
-	atomic_t pending[2];
 	spinlock_t deferred_lock;
 	struct bio_list deferred;
 
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 7cd36e4d13101..5b106ed13fc1b 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -130,11 +130,13 @@ static void rq_end_stats(struct mapped_device *md, struct request *orig)
  */
 static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
 {
-	atomic_dec(&md->pending[rw]);
+	atomic_dec(&dm_disk(md)->part0.in_flight[rw]);
 
 	/* nudge anyone waiting on suspend queue */
-	if (!md_in_flight(md))
-		wake_up(&md->wait);
+	if (unlikely(waitqueue_active(&md->wait))) {
+		if (!md_in_flight(md))
+			wake_up(&md->wait);
+	}
 
 	/*
 	 * dm_put() must be at the end of this function. See the comment above
@@ -436,7 +438,7 @@ ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
 static void dm_start_request(struct mapped_device *md, struct request *orig)
 {
 	blk_mq_start_request(orig);
-	atomic_inc(&md->pending[rq_data_dir(orig)]);
+	atomic_inc(&dm_disk(md)->part0.in_flight[rq_data_dir(orig)]);
 
 	if (unlikely(dm_stats_used(&md->stats))) {
 		struct dm_rq_target_io *tio = tio_from_request(orig);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 5f02ffa265f6d..a2acc145a0531 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -648,23 +648,20 @@ static void free_tio(struct dm_target_io *tio)
 
 int md_in_flight(struct mapped_device *md)
 {
-	return atomic_read(&md->pending[READ]) +
-	       atomic_read(&md->pending[WRITE]);
+	return atomic_read(&dm_disk(md)->part0.in_flight[READ]) +
+	       atomic_read(&dm_disk(md)->part0.in_flight[WRITE]);
 }
 
 static void start_io_acct(struct dm_io *io)
 {
 	struct mapped_device *md = io->md;
 	struct bio *bio = io->orig_bio;
-	int rw = bio_data_dir(bio);
 
 	io->start_time = jiffies;
 
 	generic_start_io_acct(md->queue, bio_op(bio), bio_sectors(bio),
 			      &dm_disk(md)->part0);
 
-	atomic_inc(&md->pending[rw]);
-
 	if (unlikely(dm_stats_used(&md->stats)))
 		dm_stats_account_io(&md->stats, bio_data_dir(bio),
 				    bio->bi_iter.bi_sector, bio_sectors(bio),
@@ -676,27 +673,30 @@ static void end_io_acct(struct dm_io *io)
 	struct mapped_device *md = io->md;
 	struct bio *bio = io->orig_bio;
 	unsigned long duration = jiffies - io->start_time;
-	int pending;
-	int rw = bio_data_dir(bio);
 
+	/*
+	 * make sure that atomic_dec in generic_end_io_acct is not reordered
+	 * with previous writes
+	 */
+	smp_mb__before_atomic();
 	generic_end_io_acct(md->queue, bio_op(bio), &dm_disk(md)->part0,
 			    io->start_time);
+	/*
+	 * generic_end_io_acct does atomic_dec, this barrier makes sure that
+	 * atomic_dec is not reordered with waitqueue_active
+	 */
+	smp_mb__after_atomic();
 
 	if (unlikely(dm_stats_used(&md->stats)))
 		dm_stats_account_io(&md->stats, bio_data_dir(bio),
 				    bio->bi_iter.bi_sector, bio_sectors(bio),
 				    true, duration, &io->stats_aux);
 
-	/*
-	 * After this is decremented the bio must not be touched if it is
-	 * a flush.
-	 */
-	pending = atomic_dec_return(&md->pending[rw]);
-	pending += atomic_read(&md->pending[rw^0x1]);
-
 	/* nudge anyone waiting on suspend queue */
-	if (!pending)
-		wake_up(&md->wait);
+	if (unlikely(waitqueue_active(&md->wait))) {
+		if (!md_in_flight(md))
+			wake_up(&md->wait);
+	}
 }
 
 /*
@@ -1892,8 +1892,6 @@ static struct mapped_device *alloc_dev(int minor)
 	if (!md->disk)
 		goto bad;
 
-	atomic_set(&md->pending[0], 0);
-	atomic_set(&md->pending[1], 0);
 	init_waitqueue_head(&md->wait);
 	INIT_WORK(&md->work, dm_wq_work);
 	init_waitqueue_head(&md->eventq);