The InnoDB data file extension code that was refactored in
MDEV-11556 fails to extend any data files when innodb_use_fallocate=ON. Even the mysql-test-run bootstrap fails:
MDEV-11687 (MariaDB Server 10.2.4) the parameter innodb_use_fallocate was deprecated, because posix_fallocate() will always be used when available. So, this regression only affects MariaDB Server 10.1.21.