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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dennis Zhou <dennis@kernel.org>,
        Josef Bacik <josef@toxicpanda.com>,
        Jens Axboe <axboe@kernel.dk>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 084/271] blk-iolatency: only account submitted bios
Date:   Wed, 24 Jul 2019 21:19:13 +0200
Message-Id: <20190724191702.387111366@linuxfoundation.org>
In-Reply-To: <20190724191655.268628197@linuxfoundation.org>
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[ Upstream commit a3fb01ba5af066521f3f3421839e501bb2c71805 ]

As is, iolatency recognizes done_bio and cleanup as ending paths. If a
request is marked REQ_NOWAIT and fails to get a request, the bio is
cleaned up via rq_qos_cleanup() and ended in bio_wouldblock_error().
This results in underflowing the inflight counter. Fix this by only
accounting bios that were actually submitted.

Signed-off-by: Dennis Zhou <dennis@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 block/blk-iolatency.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 6b8396ccb5c4..75df47ad2e79 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -565,6 +565,10 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
 	if (!blkg)
 		return;
 
+	/* We didn't actually submit this bio, don't account it. */
+	if (bio->bi_status == BLK_STS_AGAIN)
+		return;
+
 	iolat = blkg_to_lat(bio->bi_blkg);
 	if (!iolat)
 		return;
-- 
2.20.1