diff options
| -rw-r--r-- | block/blk-cgroup.c | 6 | ||||
| -rw-r--r-- | include/linux/blk-cgroup.h | 39 | ||||
| -rw-r--r-- | mm/backing-dev.c | 6 |
3 files changed, 19 insertions, 32 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index c15a26096038..2acef6a64954 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -883,8 +883,8 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css) /* this prevents anyone from attaching or migrating to this blkcg */ wb_blkcg_offline(blkcg); - /* put the base cgwb reference allowing step 2 to be triggered */ - blkcg_cgwb_put(blkcg); + /* put the base online pin allowing step 2 to be triggered */ + blkcg_unpin_online(blkcg); } /** @@ -983,11 +983,11 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css) } spin_lock_init(&blkcg->lock); + refcount_set(&blkcg->online_pin, 1); INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); INIT_HLIST_HEAD(&blkcg->blkg_list); #ifdef CONFIG_CGROUP_WRITEBACK INIT_LIST_HEAD(&blkcg->cgwb_list); - refcount_set(&blkcg->cgwb_refcnt, 1); #endif list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index e4a6949fd171..7fb7caa55a3d 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -46,6 +46,7 @@ struct blkcg_gq; struct blkcg { struct cgroup_subsys_state css; spinlock_t lock; + refcount_t online_pin; struct radix_tree_root blkg_tree; struct blkcg_gq __rcu *blkg_hint; @@ -56,7 +57,6 @@ struct blkcg { struct list_head all_blkcgs_node; #ifdef CONFIG_CGROUP_WRITEBACK struct list_head cgwb_list; - refcount_t cgwb_refcnt; #endif }; @@ -412,47 +412,34 @@ static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd) extern void blkcg_destroy_blkgs(struct blkcg *blkcg); -#ifdef CONFIG_CGROUP_WRITEBACK - /** - * blkcg_cgwb_get - get a reference for blkcg->cgwb_list + * blkcg_pin_online - pin online state * @blkcg: blkcg of interest * - * This is used to track the number of active wb's related to a blkcg. + * While pinned, a blkcg is kept online. This is primarily used to + * impedance-match blkg and cgwb lifetimes so that blkg doesn't go offline + * while an associated cgwb is still active. */ -static inline void blkcg_cgwb_get(struct blkcg *blkcg) +static inline void blkcg_pin_online(struct blkcg *blkcg) { - refcount_inc(&blkcg->cgwb_refcnt); + refcount_inc(&blkcg->online_pin); } /** - * blkcg_cgwb_put - put a reference for @blkcg->cgwb_list + * blkcg_unpin_online - unpin online state * @blkcg: blkcg of interest * - * This is used to track the number of active wb's related to a blkcg. - * When this count goes to zero, all active wb has finished so the + * This is primarily used to impedance-match blkg and cgwb lifetimes so + * that blkg doesn't go offline while an associated cgwb is still active. + * When this count goes to zero, all active cgwbs have finished so the * blkcg can continue destruction by calling blkcg_destroy_blkgs(). - * This work may occur in cgwb_release_workfn() on the cgwb_release - * workqueue. */ -static inline void blkcg_cgwb_put(struct blkcg *blkcg) +static inline void blkcg_unpin_online(struct blkcg *blkcg) { - if (refcount_dec_and_test(&blkcg->cgwb_refcnt)) + if (refcount_dec_and_test(&blkcg->online_pin)) blkcg_destroy_blkgs(blkcg); } -#else - -static inline void blkcg_cgwb_get(struct blkcg *blkcg) { } - -static inline void blkcg_cgwb_put(struct blkcg *blkcg) -{ - /* wb isn't being accounted, so trigger destruction right away */ - blkcg_destroy_blkgs(blkcg); -} - -#endif - /** * blkg_path - format cgroup path of blkg * @blkg: blkg of interest diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 62f05f605fb5..c81b4f3a7268 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -491,8 +491,8 @@ static void cgwb_release_workfn(struct work_struct *work) css_put(wb->blkcg_css); mutex_unlock(&wb->bdi->cgwb_release_mutex); - /* triggers blkg destruction if cgwb_refcnt becomes zero */ - blkcg_cgwb_put(blkcg); + /* triggers blkg destruction if no online users left */ + blkcg_unpin_online(blkcg); fprop_local_destroy_percpu(&wb->memcg_completions); percpu_ref_exit(&wb->refcnt); @@ -592,7 +592,7 @@ static int cgwb_create(struct backing_dev_info *bdi, list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list); list_add(&wb->memcg_node, memcg_cgwb_list); list_add(&wb->blkcg_node, blkcg_cgwb_list); - blkcg_cgwb_get(blkcg); + blkcg_pin_online(blkcg); css_get(memcg_css); css_get(blkcg_css); } |