devmapper: udev sync is a requirement

closes #10664
closes #4036

Signed-off-by: Vincent Batts <vbatts@redhat.com>

daemon/graphdriver/devmapper/deviceset.go

@@ -963,9 +963,9 @@ func (devices *DeviceSet) initDevmapper(doInit bool) error {
 
 	// https://github.com/docker/docker/issues/4036
 	if supported := devicemapper.UdevSetSyncSupport(true); !supported {
-		logrus.Warnf("Udev sync is not supported. This will lead to unexpected behavior, data loss and errors")
+		logrus.Errorf("Udev sync is not supported. This will lead to unexpected behavior, data loss and errors")
+		return graphdriver.ErrNotSupported
 	}
-	logrus.Debugf("devicemapper: udev sync support: %v", devicemapper.UdevSyncSupported())
 
 	if err := os.MkdirAll(devices.metadataDir(), 0700); err != nil && !os.IsExist(err) {
 		return err