setting option gpfs_images_share_mode default=copy_on_write causes setup error

[Sasikanth Eda]

Hi,

With the recent oslo_config choices support change made to gpfs driver. the configuration option "gpfs_images_share_mode" is set default to 'copy_on_write'.

cfg.StrOpt('gpfs_images_share_mode',
               default='copy_on_write',
               choices=['copy', 'copy_on_write'],

where as, in check_for_setup_error() contains;

if(self.configuration.gpfs_images_share_mode and
           self.configuration.gpfs_images_dir is None):
            msg = _('Option gpfs_images_dir is not set correctly.')
            LOG.error(msg)
            raise exception.VolumeBackendAPIException(data=msg)

If the user does not configure gpfs_images_dir, then gpfs_images_share_mode need not to initialized. But with this change, if gpfs_images_dir is not defined, gpfs_images_share_mode gets set to 'copy_on_write' which results in setup error.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/161083

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/161083
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=5ce01f4bf8d5efdc41a4e23c0474825d0773917c
Submitter: Jenkins
Branch: master

commit 5ce01f4bf8d5efdc41a4e23c0474825d0773917c
Author: Sasikanth <email address hidden>
Date: Wed Mar 4 09:04:00 2015 +0530

    Change default value of gpfs_images_share_mode to None

    This patch will assign default value of gpfs_images_share_mode
    option used in gpfs.py to None instead of 'copy_on_write'.
    Initializing it with 'copy_on_write' breaks the setup. It is
    needed only if the user configures gpfs_images_dir option.

    Change-Id: I73e91f7d41fa97a8b2f05dac55c665d1f6dedf07
    Closes-Bug: #1427713