Commit 1d933cf0 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

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 <>
Cc: Jens Axboe <>
Cc: Vivek Goyal <>
Signed-off-by: default avatarJens Axboe <>
parent fd383c2d
......@@ -1988,6 +1988,28 @@ struct bio_set *bioset_create_nobvec(unsigned int pool_size, unsigned int front_
* 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;
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;
......@@ -482,9 +482,12 @@ extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
extern unsigned int bvec_nr_vecs(unsigned short idx);
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);
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 */
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