Merge branch 'linux-5.7' of git://github.com/skeggsb/linux into drm-fixes

[linux-2.6-microblaze.git] / include / linux / blk-cgroup.h

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index e4a6949..35f8ffe 100644 (file)
--- 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 +412,38 @@ 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))
+       do {
+               if (!refcount_dec_and_test(&blkcg->online_pin))
+                       break;
                blkcg_destroy_blkgs(blkcg);
+               blkcg = blkcg_parent(blkcg);
+       } while (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