[PATCH] blk-iolatency: only account submitted bios

[PATCH] blk-iolatency: only account submitted bios

[Dennis Zhou]

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>
---
 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;
-- 
2.17.1

Re: [PATCH] blk-iolatency: only account submitted bios

[Dennis Zhou]

Hi Jens,

On Thu, May 23, 2019 at 04:10:18PM -0400, Dennis Zhou wrote:
> 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>
> ---
>  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;
> -- 
> 2.17.1
> 

Can you please take a look at this?

Thanks,
Dennis

Re: [PATCH] blk-iolatency: only account submitted bios

[Jens Axboe]

On 5/23/19 2:10 PM, Dennis Zhou wrote:
> 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.

Looks good to me, applied.

-- 
Jens Axboe