missing details about expected data-dir permissions after restoring with mariabackup

it's said that "you may have to fix file privileges" after restoring with mariabackup
in Restoring from Backups section
https://mariadb.com/kb/en/library/full-backup-and-restore-with-mariadb-backup/

there is missing information however about the expected permissions of restored data-dir
– files , db dirs, db files , etc

Finally, you may have to fix file privileges

$ chown -R mysql:mysql /var/lib/mysql/