'List snapshots created from the provided volume.
For GCE, snapshots are global, but while the volume they were
created from still exists, the source disk for the snapshot is
tracked.
:param  volume: A StorageVolume object
:type   volume: :class:`StorageVolume`
:return:  A list of Snapshot objects
:rtype:   ``list`` of :class:`GCESnapshot`'

def list_volume_snapshots(self, volume):

    volume_snapshots = []
    volume_link = volume.extra['selfLink']
    all_snapshots = self.ex_list_snapshots()
    for snapshot in all_snapshots:
        if (snapshot.extra['sourceDisk'] == volume_link):
            volume_snapshots.append(snapshot)
    return volume_snapshots
