[PATCH][v3] block: don't account for split bio's size in cgroup stats

[PATCH][v3] block: don't account for split bio's size in cgroup stats

[Josef Bacik]

We need to check in blkcg_bio_issue_check if the bio is flagged as
QUEUE_ENTERED, because if it is then we've already accounted for the
size of the IO in the cgroup stats.  We can still however account for
the extra IO since it'll be another request.

Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
v2->v3:
- this one actually compiles

 include/linux/blk-cgroup.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 3bed5e02a873..f7b910768306 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -769,8 +769,14 @@ static inline bool blkcg_bio_issue_check(struct request_queue *q,
 
 	if (!throtl) {
 		blkg = blkg ?: q->root_blkg;
-		blkg_rwstat_add(&blkg->stat_bytes, bio->bi_opf,
-				bio->bi_iter.bi_size);
+		/*
+		 * If the bio is flagged with BIO_QUEUE_ENTERED it means this
+		 * is a split bio and we would have already accounted for the
+		 * size of the bio.
+		 */
+		if (!bio_flagged(bio, BIO_QUEUE_ENTERED))
+			blkg_rwstat_add(&blkg->stat_bytes, bio->bi_opf,
+					bio->bi_iter.bi_size);
 		blkg_rwstat_add(&blkg->stat_ios, bio->bi_opf, 1);
 	}
 
-- 
2.14.3

Re: [PATCH][v3] block: don't account for split bio's size in cgroup stats

[Jens Axboe]

On 7/30/18 8:10 AM, Josef Bacik wrote:
> We need to check in blkcg_bio_issue_check if the bio is flagged as
> QUEUE_ENTERED, because if it is then we've already accounted for the
> size of the IO in the cgroup stats.  We can still however account for
> the extra IO since it'll be another request.

Applied, thanks.

-- 
Jens Axboe