[asveikau]

> if UNIX had been written by skilled Rust progammers, it would with any luck have some abstraction that provides more isolation and less potential for interference than the filesystem.

I think this is kind of absurd and my guess is you haven't worked on a filesystem driver. At a certain point there is value in admitting that race conditions are a part of the universe and developing strategies to deal with them, rather than waste a bunch of overhead trying to isolate a program from the real world or from itself. The semantics you seem to want would be really crazy for a filesystem.