Comment 9 for bug 1436999

Reviewed: https://review.openstack.org/188797
Committed: https://git.openstack.org/cgit/stackforge/os-ansible-deployment/commit/?id=389b0f0dd886388fefae0cece2844c35da28e405
Submitter: Jenkins
Branch: juno

commit 389b0f0dd886388fefae0cece2844c35da28e405
Author: git-harry <email address hidden>
Date: Fri Jun 5 14:41:25 2015 +0100

    Enable udev for lvm in cinder-volume container

    The current configuration of LVM for cinder-volume has udev_sync=0.
    This means that udev is not creating the devices that appear in /dev.
    The device files created reference specific device numbers, and these
    persist between reboots. When the host is rebooted there is no
    guarantee that device numbers allocated to the logical volumes will
    match those defined in the device files. This can be observed by
    comparing the output of 'dmsetup info' and 'ls -l /dev/mapper'.

    LVM's use of udev was disabled in an attempt to protect the host from
    the potential that uevents generated would be processed by all
    containers on the host. In practise this should not be an issue because
    there are not other containers running on a cinder host.

    This commit adjusts the lvm.conf file created so that udev is used. It
    also adds a mount entry to create a devtmpfs on /dev. Finally
    'udevadm trigger' is run to add the devices under /dev/mapper.
    Closes-Bug: #1436999
    Change-Id: I9ab35cf4438a369563f8c08870c1acfd0cc394b0