Add "all_squash" option for NFS shares

[vitosx]

Currently there is no way to map all users connecting to NFS share to specific user account (all_squash NFS export flag).
I tried manually editing /etc/exports file though shell, but it does not work. It is being overwritten with previous content.

Please allow to configure this important option. I guess operating system already allows that, it is just missing in the interface.

Synology DSM has that functionality.

[vitosx]

OK, I found location of exportfs command to reload /etc/exports file after modification.
sudo /volume0/usr/builtin/sbin/exportfs -r

Unfortunately the file is overwritten on any Shared Folders configuration change in ADM GUI. So my request to add this to interface is still valid.

BTW, /etc/exports has 777 permissions. Any user account can modify it. Asustor does not care about security very much...