btrfs: reloc: clean dirty subvols if we fail to start a transaction

If we do merge_reloc_roots() we could insert a few roots onto the dirty
subvol roots list, where we hold a ref on them.  If we fail to start the
transaction we need to run clean_dirty_subvols() in order to cleanup the
refs.

CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/relocation.c

@@ -4082,10 +4082,10 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 		goto out_free;
 	}
 	btrfs_commit_transaction(trans);
+out_free:
 	ret = clean_dirty_subvols(rc);
 	if (ret < 0 && !err)
 		err = ret;
-out_free:
 	btrfs_free_block_rsv(fs_info, rc->block_rsv);
 	btrfs_free_path(path);
 	return err;
@@ -4501,10 +4501,10 @@ int btrfs_recover_relocation(struct btrfs_root *root)
 	trans = btrfs_join_transaction(rc->extent_root);
 	if (IS_ERR(trans)) {
 		err = PTR_ERR(trans);
-		goto out_free;
+		goto out_clean;
 	}
 	err = btrfs_commit_transaction(trans);
-
+out_clean:
 	ret = clean_dirty_subvols(rc);
 	if (ret < 0 && !err)
 		err = ret;