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-rw-r--r--block/blk-cgroup.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 11f5b92d9a4..e15f731d2cd 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -303,6 +303,20 @@ struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
(p_blkg)->q, false)))
/**
+ * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
+ * @d_blkg: loop cursor pointing to the current descendant
+ * @pos_cgrp: used for iteration
+ * @p_blkg: target blkg to walk descendants of
+ *
+ * Similar to blkg_for_each_descendant_pre() but performs post-order
+ * traversal instead. Synchronization rules are the same.
+ */
+#define blkg_for_each_descendant_post(d_blkg, pos_cgrp, p_blkg) \
+ cgroup_for_each_descendant_post((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \
+ if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \
+ (p_blkg)->q, false)))
+
+/**
* blk_get_rl - get request_list to use
* @q: request_queue of interest
* @bio: bio which will be attached to the allocated request (may be %NULL)