[PATCH AUTOSEL 6.0 11/30] block: blk_add_rq_to_plug(): clear stale 'last' after flush

[Sasha Levin]

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

[ Upstream commit 878eb6e48f240d02ed1c9298020a0b6370695f24 ]

blk_mq_flush_plug_list() empties ->mq_list and request we'd peeked there
before that call is gone; in any case, we are not dealing with a mix
of requests for different queues now - there's no requests left in the
plug.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 block/blk-mq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index fe840536e6ac..d1326d48b45e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1183,6 +1183,7 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
 		   (!blk_queue_nomerges(rq->q) &&
 		    blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
 		blk_mq_flush_plug_list(plug, false);
+		last = NULL;
 		trace_block_plug(rq->q);
 	}
 
-- 
2.35.1