Mike Fleetwood authored Apr 19, 2015 and Curtis Gedak committed Jan 29, 2016

Also load the starting offset and length of the active dm-crypt mapping
into the LUKS_Info module from the dmsetup output.  This provides the
location and size of the encrypted data within the underlying block
device.

Note that dmsetup reports in units of 512 bytes sectors [1], the GParted
LUKS_Info module uses bytes and GParted Partition objects work in device
sector size units.  However the actual sector size of a dm-crypt mapping
[2] is the same as that of the underlying block device [3].

    # modprobe scsi_debug dev_size_mb=128 sector_size=4096
    # fgrep scsi_debug /sys/block/*/device/model
    /sys/block/sdd/device/model:scsi_debug
    # parted /dev/sde print
    Error: /dev/sde: unrecognised disk label
    Model: Linux scsi_debug (scsi)
    Disk /dev/sde: 134MB
[3] Sector size (logical/physical): 4096B/4096B
    Partition Table: unknown

    # cryptsetup luksFormat /dev/sde
    # cryptsetup luksOpen /dev/sde sde_crypt
    # parted /dev/mapper/sde_crypt print
    Error: /dev/mapper/sde_crypt: unrecognised disk label
    Model: Linux device-mapper (crypt) (dm)
    Disk /dev/mapper/sde_crypt: 132MB
[2] Sector size (logical/physical): 4096B/4096B
    Partition Table: unknown

    # cryptsetup status sde_crypt
    /dev/mapper/sde_crypt is active.
      type:  LUKS1
      cipher:  aes-cbc-essiv:sha256
      keysize: 256 bits
      device:  /dev/sde
      offset:  4096 sectors
      size:    258048 sectors
      mode:    read/write
    # dmsetup table --target crypt
    ...
    sde_crypt: 0 258048 crypt aes-cbc-essiv:sha256 0000000000000000000000000000000000000000000000000000000000000000 0 8:64 4096

[1] Both cryptsetup and dmsetup report the offset as 4096 and the size/
length as 258048.  128 MiB / (4096+258048) = 512 byte units, even on a
4096 byte sector size device.

Update debugging of LUKS to this:

    # ./gpartedbin
    ======================
    libparted : 2.4
    ======================
    DEBUG: /dev/sdb5: LUKS closed
    DEBUG: /dev/sdb6: LUKS open mapping /dev/mapper/sdb6_crypt, offset=2097152, length=534773760
    /dev/sde: unrecognised disk label
    DEBUG: /dev/sde: LUKS open mapping /dev/mapper/sde_crypt, offset=2097152, length=132120576

Bug 760080 - Implement read-only LUKS support