[PATCH AUTOSEL 5.1 113/219] blk-iolatency: only account submitted bios

Sasha Levin
2019-07-15T14:10:21Z

From: Dennis Zhou <dennis@kernel.org>

[ 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 507212d75ee2..58bac44ba78a 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -599,6 +599,10 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
if (!blkg || !bio_flagged(bio, BIO_TRACKED))
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