btrfs: change warning messages to error level in open_ctree()

Failure to read the fs root results in a mount error, but we log a warning
message. Same goes for checking the UUID tree, an error results in a mount
failure but we log a warning message. Change the level of the logged
messages from warning to error.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: fdmanana

fs/btrfs/disk-io.c

@@ -3642,7 +3642,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	fs_info->fs_root = btrfs_get_fs_root(fs_info, BTRFS_FS_TREE_OBJECTID, true);
 	if (IS_ERR(fs_info->fs_root)) {
 		ret = PTR_ERR(fs_info->fs_root);
-		btrfs_warn(fs_info, "failed to read fs tree: %d", ret);
+		btrfs_err(fs_info, "failed to read fs tree: %d", ret);
 		fs_info->fs_root = NULL;
 		goto fail_qgroup;
 	}
@@ -3663,8 +3663,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 		btrfs_info(fs_info, "checking UUID tree");
 		ret = btrfs_check_uuid_tree(fs_info);
 		if (ret) {
-			btrfs_warn(fs_info,
-				"failed to check the UUID tree: %d", ret);
+			btrfs_err(fs_info, "failed to check the UUID tree: %d", ret);
 			close_ctree(fs_info);
 			return ret;
 		}