check if export is already mounted before mounting it (LibvirtNFSVolumeDriver)

[Christian Berendt]

At the moment there is no check in _mount_nfs if the export is already mounted. It will be tried to mount the export and if the export is already mounted an exception is thrown following in a WARNING message that the export is already mounted. This pollutes the logs with useless WARNING messages and if there is a real exception (for example the NFS export is not reachable) we only have a WARNING in the logs.

    def _mount_nfs(self, mount_path, nfs_share, options=None, ensure=False):
        """Mount nfs export to mount path."""
        utils.execute('mkdir', '-p', mount_path)

        # Construct the NFS mount command.
        nfs_cmd = ['mount', '-t', 'nfs']
        if CONF.libvirt.nfs_mount_options is not None:
            nfs_cmd.extend(['-o', CONF.libvirt.nfs_mount_options])
        if options is not None:
            nfs_cmd.extend(options.split(' '))
        nfs_cmd.extend([nfs_share, mount_path])

        try:
            utils.execute(*nfs_cmd, run_as_root=True)
        except processutils.ProcessExecutionError as exc:
            if ensure and 'already mounted' in exc.message:
                LOG.warn(_("%s is already mounted"), nfs_share)
            else:
                raise

[Sahid Orentino (sahid-ferdjaoui)]

I patchset is in review: https://review.openstack.org/#/c/75029/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/75029
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=ce9913c6551b84d58860dfdf7ea91250d9acf148
Submitter: Jenkins
Branch: master

commit ce9913c6551b84d58860dfdf7ea91250d9acf148
Author: Leandro I. Costantino <email address hidden>
Date: Thu Feb 20 10:03:46 2014 -0300

    Check if nfs/glusterfs export is already mounted

    _mount_nfs() do not check if the nfs_share is already mounted on
    the same mnt path and pollutes logs with warnings about
    'mount.nfs: xxx busy or already mounted'.

    The patch will add the method is_mounted to libvirt/utils.py and
    use the findmnt tool to find if the same network share on the same target
    mount point is already mounted.
    If 'findmnt' is not available for any reason (part of utils-linux),
    the check will always return False.

    Closes-Bug: #1280306
    Change-Id: I1d7384ba2f1f1bb82bfbae96cca2772266d2583e