List open dm-crypt LUKS volumes
dmsetup
is useful for anything device mapper related. For Example:
[root@localhost]~# dmsetup ls --target crypt
luks-90dc732d-e183-4948-951e-c32f3f11b305 (253, 0)
[root@localhost]~#
I just looked for the same thing, a list of my luks partitions, though I wanted a mapping to the physical /dev/sdX devices.
I found a solution for that here: https://bbs.archlinux.org/viewtopic.php?id=164798
lsblk --fs