There has been a switch added to the latest CyanogenMod nightlies which allows you to change from MTP/PTP storage mode to UMS. This step allows devices to mount in mass storage mode on Linux distributions. To change mode simply goto Settings / Storage and select which mode you want. Before you can use the change you must enable a script via a PPA.
sudo add-apt-repository ppa:nilarimogard/test5
sudo apt-get update
sudo apt-get dist-upgrade