[pkg-cryptsetup-devel] Bug#548988: cryptsetup - uuid usage differs from what devmapper expects

[Milan Broz]

Bastian Blank wrote:
> I'm not sure, where this informations comes from, but LVM upstream
> decided to use the UUID of CRYPT-TEMP-* to detect the temporary luks
> devices. Also in the examples, they use CRYPT-PLAIN-* and CRYPT-LUKS1-*,
> which is not set this way by the current version of cryptsetup.

The rule is simple - all dm devices should have UUID set.

for cryptsetup <= 1.0.6 it doesn't set dm-uuid at all.

for cryptsetup == 1.0.7 it set dm-uuid for luks device, but because of problems
(people are running snapshots of the whole header and then dm-uuid is duplicated...)
I changed it (see debian bug 538221 for example).

So now, all devices created by cryptsetup have DM-UUID set in the format
 CRYPT-<devicetype>-[<uuid>-]<device name>

For example:
 CRYPT-PLAIN-name
 CRYPT-LUKS1-00000000000000000000000000000000-name
 CRYPT-TEMP-name

(All dm devices have prefix which identifies subsystem - here CRYPT-, but we have LVM-, DMRAID-,
MPATH, etc.)


For udev rules, you should still detect temporary cryptsetup detect devices by name (because of
old version of cryptsetup), but since version 1.1 it have also uuid prefix CRYPT-TEMP-.
Name remains (temporary-cryptsetup-$PID)

The lvm code already contains proper rule for udev:

ENV{DM_UUID}=="CRYPT-TEMP-?*", GOTO="dm_last_rule"
ENV{DM_UUID}!="?*", ENV{DM_NAME}=="temporary-cryptsetup-?*", GOTO="dm_last_rule"


That's the story. What's the real problem now in this bug?
The old cryptsetup do not set dm-uuid, but I see no real problem with that.

Milan