Return logical volume that stores the given path

		:param file_path: target path to search
		:param sudo: same as 'sudo' in :meth:`.WLogicalVolume.__init__`
		:return: WLogicalVolume or None (if file path is outside current mount points)

def logical_volume(cls, file_path, sudo=False):
		""" Return logical volume that stores the given path

		:param file_path: target path to search
		:param sudo: same as 'sudo' in :meth:`.WLogicalVolume.__init__`
		:return: WLogicalVolume or None (if file path is outside current mount points)
		"""
		mp = WMountPoint.mount_point(file_path)
		if mp is not None:
			name_file = '/sys/block/%s/dm/name' % mp.device_name()
			if os.path.exists(name_file):
				lv_path = '/dev/mapper/%s' % open(name_file).read().strip()
				return WLogicalVolume(lv_path, sudo=sudo)