+static int clear_free_space_tree(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ int nr;
+ int ret;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ key.objectid = 0;
+ key.type = 0;
+ key.offset = 0;
+
+ while (1) {
+ ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+ if (ret < 0)
+ goto out;
+
+ nr = btrfs_header_nritems(path->nodes[0]);
+ if (!nr)
+ break;
+
+ path->slots[0] = 0;
+ ret = btrfs_del_items(trans, root, path, 0, nr);
+ if (ret)
+ goto out;
+
+ btrfs_release_path(path);
+ }
+
+ ret = 0;
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_trans_handle *trans;
+ struct btrfs_root *tree_root = fs_info->tree_root;
+ struct btrfs_root *free_space_root = fs_info->free_space_root;
+ int ret;
+ u64 features;
+
+ trans = btrfs_start_transaction(tree_root, 0);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
+ features = btrfs_super_compat_ro_flags(fs_info->super_copy);
+ features &= ~(BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID |
+ BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE);
+ btrfs_set_super_compat_ro_flags(fs_info->super_copy, features);
+ fs_info->free_space_root = NULL;
+
+ ret = clear_free_space_tree(trans, free_space_root);
+ if (ret)
+ goto abort;
+
+ ret = btrfs_del_root(trans, tree_root, &free_space_root->root_key);
+ if (ret)
+ goto abort;
+
+ list_del(&free_space_root->dirty_list);
+
+ ret = clean_tree_block(trans, tree_root, free_space_root->node);
+ if (ret)
+ goto abort;
+ ret = btrfs_free_tree_block(trans, free_space_root,
+ free_space_root->node, 0, 1);
+ if (ret)
+ goto abort;
+
+ free_extent_buffer(free_space_root->node);
+ free_extent_buffer(free_space_root->commit_root);
+ kfree(free_space_root);
+
+ ret = btrfs_commit_transaction(trans, tree_root);
+
+abort:
+ return ret;
+}
+