Bug#245704: create seperate LVM marker list

[Alex Owen <owen@cus.org.uk>]

Hi,

I have been thinking about this today as I want to do LVM on Software
RAID.

We need an /lib/partman/commit.d/??get_lvm_maker (in partman-lvm)
which when the partition tables are written to disk iterates over the
/var/lib/partman/devices/*/* directories looking for method files which
contain "lvm" and write out the devfs device names to say
/tmp/lvm_markers.

lvmcfg can then be modified in function get_pvs to initialise PARTITIONS
to the contents of /tmp/lvm_markers should it exist.

This way lvmvfg does the current thing if run "standalone" but integrates
with partman if run from "within" partman.

We would probably be better in get_pvs (from lvmcfg) to do:

if [ -f /tmp/lvm_markers ] ; then
	do_new_stuff
else
	do_old_stuff
fi

I agree with Martin when he says "I guess lvmcfg-utils and mdcfg-utils
should not use /usr/lib/partconf/find-partitions at all, but some other
mechanism (look at partman files)."

I think the easiest way to safely interogate the partman files is from
within the partman framework hence the proposal of a commit.d script and a
temporary file to pass the needed info to lvmcfg.

Alex Owen