There might be a rescan for volume groups needed before checking if
the volume group is already there. Otherwise, the check for the volume
group fails which means the code tries to create the volume, but that
fails then because the volume is already there.
Here is the devstack run log:
[...]
plugin.sh:configure_backing_file:538 sudo losetup -f --show /opt/stack/data/lvm-shares-backing-file
plugin.sh:configure_backing_file:538 DEV=/dev/loop2
plugin.sh:configure_backing_file:543 sudo vgs lvm-shares
Volume group "lvm-shares" not found
Cannot process volume group lvm-shares
plugin.sh:configure_backing_file:543 sudo vgcreate lvm-shares /dev/loop2
Physical volume '/dev/loop2' is already in volume group 'lvm-shares'
Unable to add physical volume '/dev/loop2' to volume group 'lvm-shares'
/dev/loop2: physical volume not initialized.
plugin.sh:configure_backing_file:1 exit_trap
[...]
Change-Id: I0189580ae40b180249fd5846aa986052e44ce2c2