umount.crypt man page
umount.crypt — unmount a dm-crypt encrypted volume
umount.crypt [-n] directory
This option is ignored (originally is "force unmount for NFS").
Do not update /etc/mtab.
Try mounting read-only if unmounting fails. This option is currently not implemented and is ignored.
umount.crypt will unmount directory and disassociates the underlying crypto device, and loop device if such was used.
umount.crypto_LUKS(8) is an alias of umount.crypt(8).