+ ret = write_tree_block(NULL, fs_info, eb);
+
+ return ret;
+}
+
+static int change_extents_uuid(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_root *root = fs_info->extent_root;
+ struct btrfs_path path;
+ struct btrfs_key key = {0, 0, 0};
+ int ret = 0;
+
+ btrfs_init_path(&path);
+ /*
+ * Here we don't use transaction as it will takes a lot of reserve
+ * space, and that will make a near-full btrfs unable to change uuid
+ */
+ ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+ if (ret < 0)
+ goto out;
+
+ while (1) {
+ struct btrfs_extent_item *ei;
+ struct extent_buffer *eb;
+ u64 flags;
+ u64 bytenr;
+
+ btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+ if (key.type != BTRFS_EXTENT_ITEM_KEY &&
+ key.type != BTRFS_METADATA_ITEM_KEY)
+ goto next;
+ ei = btrfs_item_ptr(path.nodes[0], path.slots[0],
+ struct btrfs_extent_item);
+ flags = btrfs_extent_flags(path.nodes[0], ei);
+ if (!(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
+ goto next;
+
+ bytenr = key.objectid;
+ eb = read_tree_block(fs_info, bytenr, 0);
+ if (IS_ERR(eb)) {
+ error("failed to read tree block: %llu", bytenr);
+ ret = PTR_ERR(eb);
+ goto out;
+ }
+ ret = change_header_uuid(root, eb);
+ free_extent_buffer(eb);
+ if (ret < 0) {
+ error("failed to change uuid of tree block: %llu",
+ bytenr);
+ goto out;
+ }
+next:
+ ret = btrfs_next_item(root, &path);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ ret = 0;
+ goto out;
+ }
+ }
+
+out:
+ btrfs_release_path(&path);
+ return ret;
+}
+
+static int change_device_uuid(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
+ int slot)
+{
+ struct btrfs_dev_item *di;
+ int ret = 0;
+
+ di = btrfs_item_ptr(eb, slot, struct btrfs_dev_item);
+ if (!memcmp_extent_buffer(eb, fs_info->new_fsid,
+ (unsigned long)btrfs_device_fsid(di),
+ BTRFS_FSID_SIZE))
+ return ret;
+
+ write_extent_buffer(eb, fs_info->new_fsid,
+ (unsigned long)btrfs_device_fsid(di),
+ BTRFS_FSID_SIZE);
+ ret = write_tree_block(NULL, fs_info, eb);
+
+ return ret;
+}
+
+static int change_devices_uuid(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_root *root = fs_info->chunk_root;
+ struct btrfs_path path;
+ struct btrfs_key key = {0, 0, 0};
+ int ret = 0;
+
+ btrfs_init_path(&path);
+ /* No transaction again */
+ ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+ if (ret < 0)
+ goto out;
+
+ while (1) {
+ btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+ if (key.type != BTRFS_DEV_ITEM_KEY ||
+ key.objectid != BTRFS_DEV_ITEMS_OBJECTID)
+ goto next;
+ ret = change_device_uuid(fs_info, path.nodes[0], path.slots[0]);
+ if (ret < 0)
+ goto out;
+next:
+ ret = btrfs_next_item(root, &path);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ ret = 0;
+ goto out;
+ }
+ }
+out:
+ btrfs_release_path(&path);
+ return ret;
+}
+
+static int change_fsid_prepare(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_root *tree_root = fs_info->tree_root;
+ u64 flags = btrfs_super_flags(fs_info->super_copy);
+ int ret = 0;
+
+ flags |= BTRFS_SUPER_FLAG_CHANGING_FSID;
+ btrfs_set_super_flags(fs_info->super_copy, flags);
+
+ memcpy(fs_info->super_copy->fsid, fs_info->new_fsid, BTRFS_FSID_SIZE);
+ ret = write_all_supers(fs_info);
+ if (ret < 0)
+ return ret;
+
+ /* also restore new chunk_tree_id into tree_root for restore */
+ write_extent_buffer(tree_root->node, fs_info->new_chunk_tree_uuid,
+ btrfs_header_chunk_tree_uuid(tree_root->node),
+ BTRFS_UUID_SIZE);
+ return write_tree_block(NULL, fs_info, tree_root->node);
+}
+
+static int change_fsid_done(struct btrfs_fs_info *fs_info)
+{
+ u64 flags = btrfs_super_flags(fs_info->super_copy);
+
+ flags &= ~BTRFS_SUPER_FLAG_CHANGING_FSID;
+ btrfs_set_super_flags(fs_info->super_copy, flags);
+
+ return write_all_supers(fs_info);
+}
+
+/*
+ * Return 0 for no unfinished fsid change.
+ * Return >0 for unfinished fsid change, and restore unfinished fsid/
+ * chunk_tree_id into fsid_ret/chunk_id_ret.
+ */
+static int check_unfinished_fsid_change(struct btrfs_fs_info *fs_info,
+ uuid_t fsid_ret, uuid_t chunk_id_ret)
+{
+ struct btrfs_root *tree_root = fs_info->tree_root;
+ u64 flags = btrfs_super_flags(fs_info->super_copy);
+
+ if (flags & BTRFS_SUPER_FLAG_CHANGING_FSID) {
+ memcpy(fsid_ret, fs_info->super_copy->fsid, BTRFS_FSID_SIZE);
+ read_extent_buffer(tree_root->node, chunk_id_ret,
+ btrfs_header_chunk_tree_uuid(tree_root->node),
+ BTRFS_UUID_SIZE);
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * Change fsid of a given fs.
+ *
+ * If new_fsid_str is not given, use a random generated UUID.
+ * Caller should check new_fsid_str is valid
+ */
+static int change_uuid(struct btrfs_fs_info *fs_info, const char *new_fsid_str)
+{
+ uuid_t new_fsid;
+ uuid_t new_chunk_id;
+ uuid_t old_fsid;
+ char uuid_buf[BTRFS_UUID_UNPARSED_SIZE];
+ int ret = 0;
+
+ if (check_unfinished_fsid_change(fs_info, new_fsid, new_chunk_id)) {
+ if (new_fsid_str) {
+ uuid_t tmp;
+
+ uuid_parse(new_fsid_str, tmp);
+ if (memcmp(tmp, new_fsid, BTRFS_FSID_SIZE)) {
+ error(
+ "new fsid %s is not the same with unfinished fsid change",
+ new_fsid_str);
+ return -EINVAL;
+ }
+ }
+ } else {
+ if (new_fsid_str)
+ uuid_parse(new_fsid_str, new_fsid);
+ else
+ uuid_generate(new_fsid);
+
+ uuid_generate(new_chunk_id);
+ }
+ fs_info->new_fsid = new_fsid;
+ fs_info->new_chunk_tree_uuid = new_chunk_id;
+
+ memcpy(old_fsid, (const char*)fs_info->fsid, BTRFS_UUID_SIZE);
+ uuid_unparse(old_fsid, uuid_buf);
+ printf("Current fsid: %s\n", uuid_buf);
+
+ uuid_unparse(new_fsid, uuid_buf);
+ printf("New fsid: %s\n", uuid_buf);
+ /* Now we can begin fsid change */
+ printf("Set superblock flag CHANGING_FSID\n");
+ ret = change_fsid_prepare(fs_info);
+ if (ret < 0)
+ goto out;