When and why to deprecate filesystems

I think it was Eric Biederman who proposed that some file systems should only compile under User Mode Linux. That's config which let's you create an executable kernel which you can boot with ./linux. Then you would mount the image from the UML kernel and export it over NFS or whatever to the real kernel.

The advantage is if the UML kernel crashes, that's just an application. It doesn't take down your whole system. The disadvantage is that it would be slower but if it's a USB disk, then it's not going to be fast in the first place. We would only do this for less used and less trusted filesystems.

It wouldn't be super hard to create a set of tools which would remove the complexity for the user. Everyone who hears the idea is like, "Yes. That sounds very easy to do from a technical perspective which makes it too boring to do." So no one has implemented the idea. But it's a good idea.