diff options
Diffstat (limited to 'block/blk-cgroup.c')
| -rw-r--r-- | block/blk-cgroup.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 14367499cfed..3b6a0e1265aa 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -463,6 +463,7 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg, rcu_assign_pointer(blkg->q, q); blkg->blkcg = blkcg; blkg->plid = pol->plid; + blkg->refcnt = 1; cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path)); /* alloc per-policy data */ @@ -633,6 +634,29 @@ void blkg_destroy_all(struct request_queue *q) } } +static void blkg_rcu_free(struct rcu_head *rcu_head) +{ + blkg_free(container_of(rcu_head, struct blkio_group, rcu_head)); +} + +void __blkg_release(struct blkio_group *blkg) +{ + /* release the extra blkcg reference this blkg has been holding */ + css_put(&blkg->blkcg->css); + + /* + * A group is freed in rcu manner. But having an rcu lock does not + * mean that one can access all the fields of blkg and assume these + * are valid. For example, don't try to follow throtl_data and + * request queue links. + * + * Having a reference to blkg under an rcu allows acess to only + * values local to groups like group stats and group rate limits + */ + call_rcu(&blkg->rcu_head, blkg_rcu_free); +} +EXPORT_SYMBOL_GPL(__blkg_release); + static void blkio_reset_stats_cpu(struct blkio_group *blkg) { struct blkio_group_stats_cpu *stats_cpu; |