[PATCH v3 2/2] block: use blk_mq_plug() wrapper consistently in the block layer

[Pankaj Raghav <p.raghav@samsung.com>]

Use blk_mq_plug() wrapper to get the plug instead of directly accessing
it in the block layer.

Either of the changes should not have led to a bug in zoned devices:

- blk_execute_rq_nowait:
  Only passthrough requests can use this function, and plugging can be
  performed on those requests in zoned devices. So no issues directly
  accessing the plug.

- blk_flush_plug in bio_poll:
  As we don't plug the requests that require a zone lock in the first
  place, flushing should not have any impact. So no issues directly
  accessing the plug.

This is just a cleanup patch to use this wrapper to get the plug
consistently across the block layer.

Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
 block/blk-core.c | 2 +-
 block/blk-mq.c   | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 203be672da52..d0e97de216db 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -850,7 +850,7 @@ int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags)
 	    !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
 		return 0;
 
-	blk_flush_plug(current->plug, false);
+	blk_flush_plug(blk_mq_plug(bio), false);
 
 	if (bio_queue_enter(bio))
 		return 0;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index c11949d66163..5bf245c4bf0a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1209,12 +1209,14 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
  */
 void blk_execute_rq_nowait(struct request *rq, bool at_head)
 {
+	struct blk_plug *plug = blk_mq_plug(rq->bio);
+
 	WARN_ON(irqs_disabled());
 	WARN_ON(!blk_rq_is_passthrough(rq));
 
 	blk_account_io_start(rq);
-	if (current->plug)
-		blk_add_rq_to_plug(current->plug, rq);
+	if (plug)
+		blk_add_rq_to_plug(plug, rq);
 	else
 		blk_mq_sched_insert_request(rq, at_head, true, false);
 }
-- 
2.25.1