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authorTejun Heo <tj@kernel.org>2015-05-22 17:13:24 -0400
committerJens Axboe <axboe@fb.com>2015-06-02 08:33:34 -0600
commit1d933cf096e3aea15f1aec8297657b7a846fab63 (patch)
tree43ac4eff222da7ef5c873259462d906f9e3f9a7b
parentfd383c2d3cae146337cea809de0d622b8b887e6c (diff)
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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: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r--block/bio.c24
-rw-r--r--include/linux/bio.h3
2 files changed, 26 insertions, 1 deletions
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 */