[PATCH AUTOSEL 5.0 44/66] blk-mq: do not reset plug->rq_count before the list is sorted

Sasha Levin
2019-04-24T14:38:03Z

From: Dongli Zhang <dongli.zhang@oracle.com>

[ Upstream commit bcc816dfe51ab86ca94663c7b225f2d6eb0fddb9 ]

We would never be able to sort the list if we first reset plug->rq_count
which is used in conditional check later.

Fixes: ce5b009cff19 ("block: improve logic around when to sort a plug list")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
---
block/blk-mq.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 97eba6d23425..5a2585d69c81 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1716,11 +1716,12 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
unsigned int depth;

list_splice_init(&plug->mq_list, &list);
- plug->rq_count = 0;

if (plug->rq_count > 2 && plug->multiple_queues)
list_sort(NULL, &list, plug_rq_cmp);

+ plug->rq_count = 0;
+
this_q = NULL;
this_hctx = NULL;
this_ctx = NULL;
--
2.19.1