According to documentation, max_long_data_size is still present in MariaDB:

https://mariadb.com/kb/en/mariadb/documentation/managing-mariadb/optimization-and-tuning/system-variables/server-system-variables/#max_long_data_size

This variable was removed in Oracle's MySQL 5.6, and it's functionality was replaced with max_allowed_packet:

http://dev.mysql.com/doc/refman/5.5/en/server-system-variables.html#sysvar_max_long_data_size

Is there any reason to keep max_long_data_size in MariaDB? Some users think it should be removed.