diff -r 41243548e445 extent_io.c
--- a/extent_io.c	Tue Jun 10 10:40:46 2008 -0400
+++ b/extent_io.c	Tue Jun 10 14:09:20 2008 -0400
@@ -173,6 +173,38 @@ static struct rb_node *tree_insert(struc
 	rb_link_node(node, parent, p);
 	rb_insert_color(node, root);
 	return NULL;
+}
+
+/*
+ * tree_insert_left - insert split off node to a /known/ left node in a tree
+ * @root:	root of the whole tree
+ * @parent:	new node's parent
+ * @child:	new node
+ *
+ * Since we /know/ the position to insert into (the /left/ of the
+ * given parent), we can short-circuit the complete tree search.
+ *
+ * There are really two cases:
+ *	(1) The parent's left is NULL, this means that the new node is
+ *	    to be placed there.
+ *
+ *	(2) The parent's left is non-NULL, we then search for the
+ *	    right-most decendent of the parent's left-child. This is
+ *	    a simple decent down the right links.
+ *
+ * Note: We could (should?) complicate the code to add in checks for
+ *       already existing (or overlapping) entries...
+ */
+static void tree_insert_left(struct rb_root *root, struct rb_node *parent,
+			     struct rb_node *child)
+{
+	struct rb_node **link;
+
+	for (link = &parent->rb_left; *link; link = &parent->rb_right)
+		parent = *link;
+
+	rb_link_node(child, parent, link);
+	rb_insert_color(child, root);
 }
 
 static struct rb_node *__etree_search(struct extent_io_tree *tree, u64 offset,
@@ -369,20 +401,12 @@ static int split_state(struct extent_io_
 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 		       struct extent_state *prealloc, u64 split)
 {
-	struct rb_node *node;
 	prealloc->start = orig->start;
 	prealloc->end = split - 1;
 	prealloc->state = orig->state;
 	orig->start = split;
 
-	node = tree_insert(&tree->state, prealloc->end, &prealloc->rb_node);
-	if (node) {
-		struct extent_state *found;
-		found = rb_entry(node, struct extent_state, rb_node);
-		printk("found node %Lu %Lu on insert of %Lu %Lu\n", found->start, found->end, prealloc->start, prealloc->end);
-		free_extent_state(prealloc);
-		return -EEXIST;
-	}
+	tree_insert_left(&tree->state, &orig->rb_node, &prealloc->rb_node);
 	prealloc->tree = tree;
 	return 0;
 }