Comment 12 for bug 1628768

Reviewed: https://review.openstack.org/467267
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=bc1e8d6782106ec1f0fb4ebb1afa3f7269a4f063
Submitter: Jenkins
Branch: driverfixes/newton

commit bc1e8d6782106ec1f0fb4ebb1afa3f7269a4f063
Author: Gorka Eguileor <email address hidden>
Date: Thu May 18 10:28:43 2017 +0200

    NFS Backup: Fix overwritting backups

    When using the NFS backup driver if we do multiple backups using the
    same container we end up overwriting older backups.

    The issue comes from a misunderstanding in the Posix backup driver of
    the purpose of the "prefix" metadata used in the ChunkedBackupDriver
    base class.

    This prefix is for the name of the backup objects to store, but unlike
    the prefix for the volumes, here it must be unique as the base driver
    will only add numbers to identify the chunk (for the volume we add the
    volume id). Unfortunately the Posix driver just assumed that the prefix
    had the same meaning as the prefix for volumes thus making one backups
    override one another.

    This patch changes the prefix generated by the Posix driver so we have
    the following format: "volume_$VOL_ID_$TIMESTAMP_backup_$BACK_ID", thus
    allowing multiple backups in the same container.

    The new name is backward compatible with existing backups because the
    new prefix will only be used on new backups as the prefix for already
    existing backups is stored in the DB.

    Change-Id: I2903c27633facde6370d95ba0b9e06025ccaef26
    Closes-Bug: #1628768
    (cherry picked from commit 535e71797031c3d3e3a5e2023c5ede470b02e3a7)
    (cherry picked from commit 640b9dc2b739b04f1f7d70c2172f5b5fbc3b9b28)