This is again my bad. Could you run yum update command please? I changed repo locations recently and failed to link our jenkins jobs properly.
Other users updating Rockstor from UI should automatically pick up the new 4.6 kernel and btrfs-progs 4.6. No need to run yum update. But if you have updated Rockstor in the last 10-15 min, you need to run it. Sorry @aehinson.