Comment 1 for bug 1543181

Reviewed: https://review.openstack.org/277402
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=33749d2875b4e63ad8f663a734cd087980489b6e
Submitter: Jenkins
Branch: master

commit 33749d2875b4e63ad8f663a734cd087980489b6e
Author: Matthew Booth <email address hidden>
Date: Mon Feb 8 12:41:06 2016 +0000

    Fix fallocate test on newer util-linux

    Newer util-linux raises an error when calling fallocate with the -n
    option if the target file does not already exist. This is because the
    -n option directs it to retain the file's existing size. A
    non-existent file does not have an existing size. fallocate in older
    releases of util-linux creates a zero-sized file in this case. This
    results in _can_fallocate() always returning false, and therefore
    never preallocating.

    While this may reasonably be argued to be a regression in util-linux,
    the -n option doesn't make sense here anyway, so we remove it.

    Closes-Bug: #1543181

    Change-Id: Ie96fa71e7d2641d30572b8eda5609dd3ca5b6708