Comment 27 for bug 1642111

Reviewed: https://review.openstack.org/510168
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=a2b7b8d74a2dded1a38354321f5627d7375d7ee2
Submitter: Jenkins
Branch: master

commit a2b7b8d74a2dded1a38354321f5627d7375d7ee2
Author: Sean McGinnis <email address hidden>
Date: Fri Oct 6 10:55:22 2017 -0500

    Add retries to LVM logical volume activation

    We are running into failures activating snapshots where the syslog shows
    the output "thin: Unable to activate thin device while pool is suspended"
    when attempting to use quickly after creation. This appears to be a race
    where there are still internal things being done after the snapshot is
    created.

    This is a bit of a punt, but with local testing the thin pool state either
    does not visibily change or transitions so fast that it is hard to capture
    the state transition in the vgdisplay. Since we know this operations works
    most of the time, it would seem we are just giving up before the pool gets
    back into the right state to do this activation.

    Rather than trying to get the thin pool state and parse the output of the
    command, just adding retries to the operation that back off between each
    attempt. Based on what we've seen with successful runs, this should allow
    it to fail while the pool is in this transitional state and attempt again
    later when hopefully things have settled.

    Change-Id: I3e7037b3571665251db8dee2cf22cab1297106c9
    Closes-bug: #1642111