Happy to read you’re running your Samba! 
(and hope you won’t have same issues I’m testing with new Centos 7 1611: bad samba linking stopping ntpd, ping, etc)
Talking about SELinux: @phillxnet & @suman any idea about it supposed to be disabled on Rockstor but sometime ON??
M.
In the thread you linked to (or one linked from there), I think I noted that someone had had the same situation when manually adjusting parameters at install to force BTRFS. I had to do the same thing, as my first attempt at install somehow managed to set it to LVM instead. Could be a common cause meaning that the wrong config is getting picked up somewhere at install time??