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blkcg: change blkg reference counting to use percpu_ref

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Now that every bio is associated with a blkg, this puts the use of
blkg_get, blkg_try_get, and blkg_put on the hot path. This switches over
the refcnt in blkg to use percpu_ref.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Dennis Zhou (Facebook)
2018-09-11 14:41:36 -04:00
committed by Jens Axboe
parent e2b0989954
commit b3b9f24f5f
2 changed files with 44 additions and 35 deletions
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15
include/linux/blk-cgroup.h
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@@ -126,7 +126,7 @@ struct blkcg_gq {
struct request_list rl;
/* reference count */
atomic_t refcnt;
struct percpu_ref refcnt;
/* is this blkg online? protected by both blkcg and q locks */
bool online;
@@ -490,8 +490,7 @@ static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
*/
static inline void blkg_get(struct blkcg_gq *blkg)
{
WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
atomic_inc(&blkg->refcnt);
percpu_ref_get(&blkg->refcnt);
}
/**
@@ -503,7 +502,7 @@ static inline void blkg_get(struct blkcg_gq *blkg)
*/
static inline struct blkcg_gq *blkg_try_get(struct blkcg_gq *blkg)
{
if (atomic_inc_not_zero(&blkg->refcnt))
if (percpu_ref_tryget(&blkg->refcnt))
return blkg;
return NULL;
}
@@ -517,23 +516,19 @@ static inline struct blkcg_gq *blkg_try_get(struct blkcg_gq *blkg)
*/
static inline struct blkcg_gq *blkg_try_get_closest(struct blkcg_gq *blkg)
{
while (!atomic_inc_not_zero(&blkg->refcnt))
while (!percpu_ref_tryget(&blkg->refcnt))
blkg = blkg->parent;
return blkg;
}
void __blkg_release_rcu(struct rcu_head *rcu);
/**
* blkg_put - put a blkg reference
* @blkg: blkg to put
*/
static inline void blkg_put(struct blkcg_gq *blkg)
{
WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
if (atomic_dec_and_test(&blkg->refcnt))
call_rcu(&blkg->rcu_head, __blkg_release_rcu);
percpu_ref_put(&blkg->refcnt);
}
/**