[Pkg-cryptsetup-devel] RFC: Adding a lvm parameter to crypttab

[David Härdeman]

In order to support both the scenario of root-on-crypto-on-lvm-on-something
and root-on-lvm-on-crypto-on-something, I think it would be a good idea to add
a lvm parameter to crypttab.

Some of this could be auto-probed today (especially for initramfs crypto-root)
but doing so is both fragile (for example, there has been several reports
already against the lvm detection I added to klibc because it turns out people
can have both fs and lvm signatures on devices which they do not use for lvm
any longer) and potentially dangerous.

So, I suggest a parameter of the form lvm=VG to be supported by crypttab, e.g:
cryptroot    /dev/sda6    none    luks,lvm=rootvg

The lvm parameter would let let cryptsetup know that it should also run
"vgchange -ay VGNAME" after the device-mapper device has been setup. And it
would also let cryptsetup know that it should try to deactivate and remove the
vg before it disables the mapping.

Before I wen ahead and whipped up a patch and filed a bug for this I wanted to
see if there are any objections or comments to my proposal?

Regards,
David