[rbd mirror] integrity of journal-based image mirror

Hi, Say, the source image is being updated and data is mirrored to destination continuously. Suddenly, networking of source is down and destination will be promoted and used to restore the VM. Is that going to cause any FS issue and, for example, fsck needs to be invoked to check and repair FS? Is there any integrity check during journal-based mirror to avoid "partial" update caused by networking issue? Any insight from dev or experiences from users is appreciated. Thanks! Tony