[PATCH] rbtree: support functions used by the io schedulers

They all duplicate macros to check for empty root and/or node, and
clearing a node. So put those in rbtree.h.

Signed-off-by: Jens Axboe <axboe@suse.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
index f37006f21664..8d5382e62c08 100644
--- a/include/linux/rbtree.h
+++ b/include/linux/rbtree.h
@@ -132,6 +132,10 @@ static inline void rb_set_color(struct rb_node *rb, int color)
 #define RB_ROOT (struct rb_root) { NULL, }
 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
 
+#define RB_EMPTY_ROOT(root)     ((root)->rb_node == NULL)
+#define RB_EMPTY_NODE(node)     (rb_parent(node) != node)
+#define RB_CLEAR_NODE(node)     (rb_set_parent(node, node))
+
 extern void rb_insert_color(struct rb_node *, struct rb_root *);
 extern void rb_erase(struct rb_node *, struct rb_root *);