def METHOD_NAME(self):
    dev = None
    try:
        mode = os.stat(self.device)[ST_MODE]
    except:
        self.log.debug("can not stat %s" % self.device)
        return None
    if S_ISCHR(mode):
        dev = self.device
    else:
        mnt = getmount(self.device)
        if self.Mounts is None:
            self.Mounts = Mounts()
        m = self.Mounts.has_param("mnt", mnt)
        if m is None:
            self.log.debug("can't find dev %(dev)s mounted in %(mnt)s in mnttab"%dict(mnt=mnt, dev=self.device))
            return None
        dev = m.dev
    return dev