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Commit d459d853 authored by Dennis Zhou's avatar Dennis Zhou Committed by Jens Axboe
Browse files

blkcg: reassociate bios when make_request() is called recursively 



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: a7b39b4e ("blkcg: always associate a bio with a blkg")
Reported-by: default avatarValdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: default avatarDennis Zhou <dennis@kernel.org>
Tested-by: default avatarValdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b2c3fa54

block/bio.c

+20 −0
Original line number Diff line number Diff line
@@ -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

block/blk-core.c

+1 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/bio.h

+3 −0
Original line number Diff line number Diff line
@@ -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) { }