Enabling volume_copy_bps_limit make nfs volume copy fail

[Tomoki Sekiyama]

With NFS backend driver, it fails by exception in utils.get_blkdev_major_minor() to copy volumes if volume_copy_bps_limit is set to non zero.

For instance, when
    cinder upload-to-image --disk-format qcow2 vol1 img1
is executed, it fails to upload by an exception

OSError: [Errno 2] No such file or directory: 'nfs-server.example.com:/path/to/storage'

in file "/opt/stack/cinder/cinder/utils.py", line 812, in get_blkdev_major_minor.

As blkio cgroup doesn't support NFS mount, get_blkdev_major_minor() should return None for files in NFS.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/109137
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=38096b2405899adc63b7ee5f85a4d3b2a66991a7
Submitter: Jenkins
Branch: master

commit 38096b2405899adc63b7ee5f85a4d3b2a66991a7
Author: Tomoki Sekiyama <email address hidden>
Date: Fri Jul 18 22:23:55 2014 -0400

    Avoid OSError in get_blkdev_major_minor with network filesystems

    To avoid OSError (File not found) thrown for volumes on network filesystems
    during volume copy with CONF.volume_copy_bps_limit, this patch adds a check
    of whether the specified file is on the local block devices to
    get_blkdev_major_minor().

    It also adds a testcase for get_blkdev_major_minor with a file on nfs and
    fixes it with a regular file.

    Change-Id: I0b725bba07ad632bfa0c922bfce1652efe59b033
    Closes-Bug: 1348230