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From:   Dongli Zhang <dongli.zhang@oracle.com>
To:     axboe@kernel.dk
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/1] blk-mq: do not reset plug->rq_count before the list is sorted
Date:   Thu,  4 Apr 2019 10:57:44 +0800
Message-Id: <1554346664-24038-1-git-send-email-dongli.zhang@oracle.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
---
 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 3ff3d7b..c162718 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1711,11 +1711,12 @@ 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;
-- 
2.7.4