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-rw-r--r--block/blk-cgroup.h18
1 files changed, 18 insertions, 0 deletions
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 24597309e23d..b26ed58899fe 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -94,8 +94,13 @@ struct blkcg_gq {
struct list_head q_node;
struct hlist_node blkcg_node;
struct blkcg *blkcg;
+
+ /* all non-root blkcg_gq's are guaranteed to have access to parent */
+ struct blkcg_gq *parent;
+
/* request allocation list for this blkcg-q pair */
struct request_list rl;
+
/* reference count */
int refcnt;
@@ -181,6 +186,19 @@ static inline struct blkcg *bio_blkcg(struct bio *bio)
}
/**
+ * blkcg_parent - get the parent of a blkcg
+ * @blkcg: blkcg of interest
+ *
+ * Return the parent blkcg of @blkcg. Can be called anytime.
+ */
+static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
+{
+ struct cgroup *pcg = blkcg->css.cgroup->parent;
+
+ return pcg ? cgroup_to_blkcg(pcg) : NULL;
+}
+
+/**
* blkg_to_pdata - get policy private data
* @blkg: blkg of interest
* @pol: policy of interest