Comment 7 for bug 1367826

Reviewed: https://review.openstack.org/120713
Committed: https://git.openstack.org/cgit/openstack/swift/commit/?id=09bdc87cbc1e7bc1918f9b5094bec266b6761d75
Submitter: Jenkins
Branch: master

commit 09bdc87cbc1e7bc1918f9b5094bec266b6761d75
Author: Christian Schwede <email address hidden>
Date: Thu Sep 11 08:01:51 2014 +0000

    Return correct number of changed partitions

    When a ring is rebalanced the number of changed partitions is counted.
    Before this patch partitions might be rebalanced, but actually no data
    is moved - for example, when a partition is assigned to the same device
    as before. This results in a wrong number of reassigned partitions that
    is shown to the user.

    This patch remembers the partition allocation before the rebalance, and
    compares it to the new allocation after a rebalance. Only partitions
    that are stored on a different device than before are counted.

    Partial-Bug: 1367826
    Also-By: Florent Flament <email address hidden>
    Change-Id: Iacfd514df3af351791f9191cef78cff1b3e2645f