[PATCH 4.19 084/271] blk-iolatency: only account submitted bios

From: Greg Kroah-Hartman
Date: Thu Jul 25 2019 - 11:01:53 EST


[ 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@xxxxxxxxxx>
Cc: Josef Bacik <josef@xxxxxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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