From the Linux conference video I watched I think they have the wrong approach. They’re trying to improve a bad api by adding types do describe it’s awkward behavior. The C programmers who love the Linux style want to be able to change semantics or api without modifying rust code. The solution is straight forward, build an adapter later in C that has well describable and clean semantics. Since it is C and in the kernel and has clear semantics the C programmers can maintain it without having to look at Rust. Perhaps the general lack of encapsulation and layers in the kernel will defeat them as they will need a lot of adapter layers. But for file systems it might be achievable.