The device mapper sets the DM_UDEV_DISABLE_OTHER_RULES_FLAG signal to indicate that other rules should not react to the event. However, systemd previously considered the related device not to be ready for use, which is only true for the ADD event. As a consequence, overlaying file systems on the devices were unmounted even if only one path became unavailable, but other paths were still accessible. With this update, the device is marked as unusable only in case of ADD events, and CHANGE events are ignored. As a result, file systems are no longer unmounted if a CHANGE event occurs.