[Renate]

I have to do more work on this. I don't know what the problem is yet. The updates are successful and all the hashes check.

The update engine allocates files for spare space but then it accesses this space using a device mapper (linear target). That means that I have to mount the flash (internal or external) by device mapping it first and then mounting the dm. My dm is mapped by the update engine's dm. Apparently that is the only way to share a physical device between a file system and a mapper. That works fine now.