btrfs: remove duplicated uuid tree existence check in btrfs_uuid_tree_add()

There's no point in checking if the uuid root exists in
btrfs_uuid_tree_add(), since we already do it in btrfs_uuid_tree_lookup().
We can just remove the check from btrfs_uuid_tree_add() and make
btrfs_uuid_tree_lookup() return -EINVAL instead of -ENOENT in case the
uuid tree does not exists.

Reviewed-by: Boris Burkov <[email protected]>
Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Filipe Manana <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: fdmanana

fs/btrfs/uuid-tree.c

@@ -35,7 +35,7 @@ static int btrfs_uuid_tree_lookup(struct btrfs_root *uuid_root, const u8 *uuid,
 	struct btrfs_key key;
 
 	if (WARN_ON_ONCE(!uuid_root))
-		return -ENOENT;
+		return -EINVAL;
 
 	path = btrfs_alloc_path();
 	if (!path)
@@ -92,9 +92,6 @@ int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans, const u8 *uuid, u8 typ
 	if (ret != -ENOENT)
 		return ret;
 
-	if (WARN_ON_ONCE(!uuid_root))
-		return -EINVAL;
-
 	btrfs_uuid_to_key(uuid, type, &key);
 
 	path = btrfs_alloc_path();