+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;
+
+ /* Change extents first */
+ printf("Change fsid in extents\n");
+ ret = change_extents_uuid(fs_info);
+ if (ret < 0) {
+ error("failed to change UUID of metadata: %d", ret);
+ goto out;
+ }
+
+ /* Then devices */
+ printf("Change fsid on devices\n");
+ ret = change_devices_uuid(fs_info);
+ if (ret < 0) {
+ error("failed to change UUID of devices: %d", ret);
+ goto out;
+ }
+
+ /* Last, change fsid in super */
+ memcpy(fs_info->fs_devices->fsid, fs_info->new_fsid,
+ BTRFS_FSID_SIZE);
+ memcpy(fs_info->super_copy->fsid, fs_info->new_fsid,
+ BTRFS_FSID_SIZE);
+ ret = write_all_supers(fs_info);
+ if (ret < 0)
+ goto out;
+
+ /* Now fsid change is done */
+ printf("Clear superblock flag CHANGING_FSID\n");
+ ret = change_fsid_done(fs_info);
+ fs_info->new_fsid = NULL;
+ fs_info->new_chunk_tree_uuid = NULL;
+ printf("Fsid change finished\n");
+out: