make akonadictl fsck able to startup and shutdown Akonadi (should be easy, there's code for that in akonadictl already, you just need to implement "waiting" for the startup/shutdown, best by listening for org.freedesktop.Akonadi.Server DBus service do (dis)appear)
make akonadictl fsck able to startup and shutdown the database on its own (by using the code from akstorage)
move the the current functionality from storagejanitor.cpp to akonadictl to be executed against the DB
register org.freedesktop.Akonadi.upgrading and org.freedesktop.Akonadi.Control.Lock DBus services from akonadictl fsck to notify Akonadi applications that an update/upkeep of the database is in progress and to prevent Akonadi Server from starting during that.