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Commit 1d933cf0 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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blkcg: implement bio_associate_blkcg() 



Currently, a bio can only be associated with the io_context and blkcg
of %current using bio_associate_current().  This is too restrictive
for cgroup writeback support.  Implement bio_associate_blkcg() which
associates a bio with the specified blkcg.

bio_associate_blkcg() leaves the io_context unassociated.
bio_associate_current() is updated so that it considers a bio as
already associated if it has a blkcg_css, instead of an io_context,
associated with it.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent fd383c2d

block/bio.c

+23 −1
Original line number Diff line number Diff line
@@ -1988,6 +1988,28 @@ struct bio_set *bioset_create_nobvec(unsigned int pool_size, unsigned int front_ 
EXPORT_SYMBOL(bioset_create_nobvec);



#ifdef CONFIG_BLK_CGROUP



/**

 * bio_associate_blkcg - associate a bio with the specified blkcg

 * @bio: target bio

 * @blkcg_css: css of the blkcg to associate

 *

 * Associate @bio with the blkcg specified by @blkcg_css.  Block layer will

 * treat @bio as if it were issued by a task which belongs to the blkcg.

 *

 * This function takes an extra reference of @blkcg_css which will be put

 * when @bio is released.  The caller must own @bio and is responsible for

 * synchronizing calls to this function.

 */

int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css)

{

	if (unlikely(bio->bi_css))

		return -EBUSY;

	css_get(blkcg_css);

	bio->bi_css = blkcg_css;

	return 0;

}



/**

 * bio_associate_current - associate a bio with %current

 * @bio: target bio
@@ -2005,7 +2027,7 @@ int bio_associate_current(struct bio *bio) 
{

	struct io_context *ioc;



	if (bio->bi_ioc)

	if (bio->bi_css)

		return -EBUSY;



	ioc = current->io_context;

include/linux/bio.h

+3 −0
Original line number Diff line number Diff line
@@ -482,9 +482,12 @@ extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int); 
extern unsigned int bvec_nr_vecs(unsigned short idx);



#ifdef CONFIG_BLK_CGROUP

int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);

int bio_associate_current(struct bio *bio);

void bio_disassociate_task(struct bio *bio);

#else	/* CONFIG_BLK_CGROUP */

static inline int bio_associate_blkcg(struct bio *bio,

			struct cgroup_subsys_state *blkcg_css) { return 0; }

static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }

static inline void bio_disassociate_task(struct bio *bio) { }

#endif	/* CONFIG_BLK_CGROUP */