When booting Linux into single user mode or rescue mode, you will find that unless the distro has found and enabled the logical volumes that you wont see any devices. This makes it a fun task when you need to mount, scan, resize, whatever a partition. Below are instructions on enabling your logical volumes.

lvm vgscan
lvm vgchange -ay
lvm lvs

It's as simple as that, now you should see your normal LVM devices in /dev (example: /dev/LVM-GROUP/LVM-VOLUME)