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SubjectRe: [PATCH AUTOSEL 5.2 129/249] blk-iolatency: only account submitted bios
On Mon, Jul 15, 2019 at 09:44:54AM -0400, Sasha Levin wrote:
> 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 d22e61bced86..c91b84bb9d0a 100644
> --- a/block/blk-iolatency.c
> +++ b/block/blk-iolatency.c
> @@ -600,6 +600,10 @@ 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
>

Hi Sasha,

If you're going to pick this up, c9b3007feca0 ("blk-iolatency: fix
STS_AGAIN handling") fixes this patch, so please pick that up too.

Thanks,
Dennis

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