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blkcg: reassociate bios when make_request() is called recursively

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When submitting a bio, multiple recursive calls to make_request() may
occur. This causes the initial associate done in blkcg_bio_issue_check()
to be incorrect and reference the prior request_queue. This introduces
a helper to do reassociation when make_request() is recursively called.

Fixes: a7b39b4e96 ("blkcg: always associate a bio with a blkg")
Reported-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Tested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Dennis Zhou 2018-10-20 14:56:12 -04:00 committed by Jens Axboe
parent b2c3fa5467
commit d459d853c2
3 changed files with 24 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

20
block/bio.c
View file

@ -2083,6 +2083,26 @@ int bio_associate_create_blkg(struct request_queue *q, struct bio *bio)
return ret;
}
/**
* bio_reassociate_blkg - reassociate a bio with a blkg from q
* @q: request_queue where bio is going
* @bio: target bio
*
* When submitting a bio, multiple recursive calls to make_request() may occur.
* This causes the initial associate done in blkcg_bio_issue_check() to be
* incorrect and reference the prior request_queue. This performs reassociation
* when this situation happens.
*/
int bio_reassociate_blkg(struct request_queue *q, struct bio *bio)
{
if (bio->bi_blkg) {
blkg_put(bio->bi_blkg);
bio->bi_blkg = NULL;
}
return bio_associate_create_blkg(q, bio);
}
/**
* bio_disassociate_task - undo bio_associate_current()
* @bio: target bio

1
block/blk-core.c
View file

@ -2433,6 +2433,7 @@ blk_qc_t generic_make_request(struct bio *bio)
if (q)
blk_queue_exit(q);
q = bio->bi_disk->queue;
bio_reassociate_blkg(q, bio);
flags = 0;
if (bio->bi_opf & REQ_NOWAIT)
flags = BLK_MQ_REQ_NOWAIT;

3
include/linux/bio.h
View file

@ -514,6 +514,7 @@ int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg);
int bio_associate_blkg_from_css(struct bio *bio,
struct cgroup_subsys_state *css);
int bio_associate_create_blkg(struct request_queue *q, struct bio *bio);
int bio_reassociate_blkg(struct request_queue *q, struct bio *bio);
void bio_disassociate_task(struct bio *bio);
void bio_clone_blkg_association(struct bio *dst, struct bio *src);
#else /* CONFIG_BLK_CGROUP */
@ -522,6 +523,8 @@ static inline int bio_associate_blkg_from_css(struct bio *bio,
{ return 0; }
static inline int bio_associate_create_blkg(struct request_queue *q,
struct bio *bio) { return 0; }
static inline int bio_reassociate_blkg(struct request_queue *q, struct bio *bio)
{ return 0; }
static inline void bio_disassociate_task(struct bio *bio) { }
static inline void bio_clone_blkg_association(struct bio *dst,
struct bio *src) { }