1 files changed, 44 insertions, 1 deletions

diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 34aec30e06c7..6d766a19f2bb 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -56,6 +56,7 @@ struct blkcg {
         struct list_head                all_blkcgs_node;
 #ifdef CONFIG_CGROUP_WRITEBACK
         struct list_head                cgwb_list;
+        refcount_t                      cgwb_refcnt;
 #endif
 };
 
@@ -89,7 +90,6 @@ struct blkg_policy_data {
         /* the blkg and policy id this per-policy data belongs to */
         struct blkcg_gq                 *blkg;
         int                             plid;
-        bool                            offline;
 };
 
 /*
@@ -387,6 +387,49 @@ static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
         return cpd ? cpd->blkcg : NULL;
 }
 
+extern void blkcg_destroy_blkgs(struct blkcg *blkcg);
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+/**
+ * blkcg_cgwb_get - get a reference for blkcg->cgwb_list
+ * @blkcg: blkcg of interest
+ *
+ * This is used to track the number of active wb's related to a blkcg.
+ */
+static inline void blkcg_cgwb_get(struct blkcg *blkcg)
+{
+        refcount_inc(&blkcg->cgwb_refcnt);
+}
+
+/**
+ * blkcg_cgwb_put - put a reference for @blkcg->cgwb_list
+ * @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
+ * 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)
+{
+        if (refcount_dec_and_test(&blkcg->cgwb_refcnt))
+                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