From 1d933cf096e3aea15f1aec8297657b7a846fab63 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 22 May 2015 17:13:24 -0400 Subject: 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: Tejun Heo Cc: Jens Axboe Cc: Vivek Goyal Signed-off-by: Jens Axboe --- block/bio.c | 24 +++++++++++++++++++++++- include/linux/bio.h | 3 +++ 2 files changed, 26 insertions(+), 1 deletion(-) diff --git a/block/bio.c b/block/bio.c index c4f87018fb79..2a00d349cd68 100644 --- a/block/bio.c +++ b/block/bio.c @@ -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; diff --git a/include/linux/bio.h b/include/linux/bio.h index f0291cf64cc5..5e963a6d7c14 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -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 */ -- cgit v1.2.3