Updated from webmin 1.660 to 1.670 causes me problems with my local disk space as displayed on system information. I have 6TB of space, on Raid. So has always displayed on webmin as 2.70 TB local disk space. When I run the new 1.670 the space is displayed as 1015.93 GB.
I have never had an issue with webmin before this, I reverted back to the previous version and everything if fine. Then I tried updating another two times, but always the same 'bug' will not display my 'true' disk space on system information. I am running on Debian 7 server.
I have switched back to the previous version until there is a fix. I lost all my Filesystem backup settings because of this. :(
Here is two snapshots, the first of how it looks after update, the second how it used to look displaying the correct disk total of 2.70 TB.
Webmin 1.670 did make some changes in how local disk space was computed.
Can you post the contents of the /proc/mounts file on your system?
Wait, I see the bug here - this will be fixed in the next Webmin release.