diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index a4a7a1a..b60955d 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -79,12 +79,21 @@
 	}
 }
 
-static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
-				   struct rb_node *node)
+/* simple helper to do math around the end of an extent, handling wrap */
+static u64 range_end(u64 start, u64 len)
+{
+	if (start + len < start)
+		return (u64)-1;
+	return start + len;
+}
+
+static int tree_insert(struct rb_root *root, struct extent_map *em)
 {
 	struct rb_node **p = &root->rb_node;
 	struct rb_node *parent = NULL;
-	struct extent_map *entry;
+	struct extent_map *entry = NULL;
+	struct rb_node *orig_parent = NULL;
+	u64 end = range_end(em->start, em->len);
 
 	while (*p) {
 		parent = *p;
@@ -92,19 +101,37 @@
 
 		WARN_ON(!entry->in_tree);
 
-		if (offset < entry->start)
+		if (em->start < entry->start)
 			p = &(*p)->rb_left;
-		else if (offset >= extent_map_end(entry))
+		else if (em->start >= extent_map_end(entry))
 			p = &(*p)->rb_right;
 		else
-			return parent;
+			return -EEXIST;
 	}
 
-	entry = rb_entry(node, struct extent_map, rb_node);
-	entry->in_tree = 1;
-	rb_link_node(node, parent, p);
-	rb_insert_color(node, root);
-	return NULL;
+	orig_parent = parent;
+	while (parent && em->start >= extent_map_end(entry)) {
+		parent = rb_next(parent);
+		entry = rb_entry(parent, struct extent_map, rb_node);
+	}
+	if (parent)
+		if (end > entry->start && em->start < extent_map_end(entry))
+			return -EEXIST;
+
+	parent = orig_parent;
+	entry = rb_entry(parent, struct extent_map, rb_node);
+	while (parent && em->start < entry->start) {
+		parent = rb_prev(parent);
+		entry = rb_entry(parent, struct extent_map, rb_node);
+	}
+	if (parent)
+		if (end > entry->start && em->start < extent_map_end(entry))
+			return -EEXIST;
+
+	em->in_tree = 1;
+	rb_link_node(&em->rb_node, orig_parent, p);
+	rb_insert_color(&em->rb_node, root);
+	return 0;
 }
 
 /*
@@ -310,20 +337,11 @@
 		       struct extent_map *em, int modified)
 {
 	int ret = 0;
-	struct rb_node *rb;
-	struct extent_map *exist;
 
-	exist = lookup_extent_mapping(tree, em->start, em->len);
-	if (exist) {
-		free_extent_map(exist);
-		ret = -EEXIST;
+	ret = tree_insert(&tree->map, em);
+	if (ret)
 		goto out;
-	}
-	rb = tree_insert(&tree->map, em->start, &em->rb_node);
-	if (rb) {
-		ret = -EEXIST;
-		goto out;
-	}
+
 	atomic_inc(&em->refs);
 
 	em->mod_start = em->start;
@@ -337,14 +355,6 @@
 	return ret;
 }
 
-/* simple helper to do math around the end of an extent, handling wrap */
-static u64 range_end(u64 start, u64 len)
-{
-	if (start + len < start)
-		return (u64)-1;
-	return start + len;
-}
-
 static struct extent_map *
 __lookup_extent_mapping(struct extent_map_tree *tree,
 			u64 start, u64 len, int strict)