[UPDATE] This doesn't seem to work correctly with mapped network drives, but worked on the same computer if I typed into the address bar \\smb_server_ip\share and then tried to move large amounts of data. But I was testing/implementing simultaneously, I will update again as time goes on.
Ok so I read about using the
[global] dfree command = /usr/local/bin/dfree
Along with something like this in the script
#!/bin/sh
#/usr/local/bin/dfree
df $1 | tail -1 | awk '{print $2" "$4}'
But what if you are using a network share that is mounted. That is my issue and I suspect many others. The host OS/Root doesn't have the free space and only reports the roots free space.
To simplfy this I used...
[global] dfree command = 14535344848 14535344848
The syntax is
[global] dfree command = $TOTALKB $AVAILKB
if you use these numbers its something like 14TB I beleive, not sure what would happen if you tried to copy to much data but for me I know there is TB's of free storage and I don't usually copy TB's of data so I just simplified it and went big!
Also something I read about dfree used to be called by root but is now called by another user and doesn't report back correctly so I suggest just putting numbers in as such if you can't get the "script" to work.
PS: this goes inside /etc/samba/smb.conf