Solution based on https://unix.stackexchange.com/a/73132/30851 .
- losetup --find --show --partscan --read-only /dev/lvm_vg/lvm_lv
- This will output something like: /dev/loop0
- Now we have /dev/loop0p1 and /dev/loop0p2 (partitions we were looking for)
- mount /dev/loop0p2 /mnt
