Update rbtree to version with unified parent + color

This saves 4-8 bytes per node, which can be quite a bit of memory
with blktrace.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 18 insertions, 4 deletions

diff --git a/rbtree.h b/rbtree.h
index e722b1e..4c06d98 100644
--- a/rbtree.h
+++ b/rbtree.h
@@ -98,8 +98,7 @@ static inline struct page * rb_insert_page_cache(struct inode * inode,
 
 struct rb_node
 {
-	struct rb_node *rb_parent;
-	int rb_color;
+	unsigned long  rb_parent_color;
 #define	RB_RED		0
 #define	RB_BLACK	1
 	struct rb_node *rb_right;
@@ -122,6 +121,22 @@ struct rb_root
 	const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 	(type *)( (char *)__mptr - offsetof(type,member) );})
 
+#define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
+#define rb_color(r)   ((r)->rb_parent_color & 1)
+#define rb_is_red(r)   (!rb_color(r))
+#define rb_is_black(r) rb_color(r)
+#define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
+#define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)
+
+static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
+{
+	rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
+}
+static inline void rb_set_color(struct rb_node *rb, int color)
+{
+	rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
+}
+
 #define RB_ROOT	(struct rb_root) { NULL, }
 #define	rb_entry(ptr, type, member) container_of(ptr, type, member)
 
@@ -141,8 +156,7 @@ extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
 				struct rb_node ** rb_link)
 {
-	node->rb_parent = parent;
-	node->rb_color = RB_RED;
+	node->rb_parent_color = (unsigned long )parent;
 	node->rb_left = node->rb_right = NULL;
 
 	*rb_link = node;