diff --git a/ctree.h b/ctree.h
index 32b91906..1de24290 100644
--- a/ctree.h
+++ b/ctree.h
@@ -298,6 +298,12 @@ struct btrfs_block_group_cache {
 	int cached;
 	u64 pinned;
 };
+struct btrfs_extent_ops {
+       int (*alloc_extent)(struct btrfs_root *root, u64 num_bytes,
+		           u64 hint_byte, struct btrfs_key *ins);
+       int (*free_extent)(struct btrfs_root *root, u64 bytenr,
+		          u64 num_bytes);
+};
 
 struct btrfs_fs_info {
 	u8 fsid[BTRFS_FSID_SIZE];
@@ -322,8 +328,10 @@ struct btrfs_fs_info {
 	struct mutex fs_mutex;
 	int fp;
 	u64 total_pinned;
-};
 
+	struct btrfs_extent_ops *extent_ops;
+	void *priv_data;
+};
 /*
  * in ram representation of the tree.  extent_root is used for all allocations
  * and for the extent tree extent_root root.
diff --git a/disk-io.c b/disk-io.c
index fad099a3..96cafe6b 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -396,7 +396,8 @@ struct btrfs_root *open_ctree_fd(int fp, u64 sb_bytenr)
 	fs_info->fs_root = root;
 	fs_info->tree_root = tree_root;
 	fs_info->extent_root = extent_root;
-
+	fs_info->extent_ops = NULL;
+	fs_info->priv_data = NULL;
 	extent_map_tree_init(&fs_info->extent_cache);
 	extent_map_tree_init(&fs_info->free_space_cache);
 	extent_map_tree_init(&fs_info->pending_tree);
diff --git a/extent-tree.c b/extent-tree.c
index 33aa0557..c9b2a088 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -1209,6 +1209,7 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 	struct btrfs_path *path;
 	struct btrfs_key key;
 	struct btrfs_fs_info *info = root->fs_info;
+	struct btrfs_extent_ops *ops = info->extent_ops;
 	struct btrfs_root *extent_root = info->extent_root;
 	struct extent_buffer *leaf;
 	int ret;
@@ -1272,11 +1273,13 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 		root_used = btrfs_root_used(&root->root_item);
 		btrfs_set_root_used(&root->root_item,
 					   root_used - num_bytes);
-
 		ret = btrfs_del_item(trans, extent_root, path);
-		if (ret) {
+		if (ret)
 			return ret;
-		}
+
+		if (ops && ops->free_extent)
+			ops->free_extent(root, bytenr, num_bytes);
+
 		ret = update_block_group(trans, root, bytenr, num_bytes, 0,
 					 mark_free, 0);
 		BUG_ON(ret);
@@ -1626,6 +1629,7 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 	u64 new_hint;
 	*/
 	struct btrfs_fs_info *info = root->fs_info;
+	struct btrfs_extent_ops *ops = info->extent_ops;
 	struct btrfs_root *extent_root = info->extent_root;
 	struct btrfs_extent_item extent_item;
 	struct btrfs_path *path;
@@ -1637,12 +1641,15 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 	if (new_hint < btrfs_super_total_bytes(&info->super_copy))
 		hint_byte = new_hint;
 	*/
-
 	WARN_ON(num_bytes < root->sectorsize);
-	ret = find_free_extent(trans, root, num_bytes, empty_size,
-			       search_start, search_end, hint_byte, ins,
-			       trans->alloc_exclude_start,
-			       trans->alloc_exclude_nr, data);
+	if (ops && ops->alloc_extent) {
+		ret = ops->alloc_extent(root, num_bytes, hint_byte, ins);
+	} else {
+		ret = find_free_extent(trans, root, num_bytes, empty_size,
+				        search_start, search_end, hint_byte,
+					ins, trans->alloc_exclude_start,
+					trans->alloc_exclude_nr, data);
+	}
 	BUG_ON(ret);
 	if (ret)
 		return ret;