[throwii]

Any rewrite must be carefully evaluated, true. And it may not be advisable. I'm trying to understand the issues.

Are they not solvable because the kernel does not give enough guarantees as it gives to userspace, because the c-interfaces of the kernel have to be wrapped in unsafe or because of other reasons (architecture, data model, kernel constraints, ...)?

[ldrndll]

I think the issue is that you haven’t understood the issue, and just proposed using Rust. Don’t get me wrong, I’m a huge fan of Rust, but seeing people blindly suggest it as a panacea gets frustrating for people. The reality is that when people talk about Rust being fact, it’s because a decently optimised Rust program might be comparable to an equivalent C program. C is generally not the problem when it comes to performance issues in the kernel, which means rewriting that thing in Rust wouldn’t magically make it faster.

The issue will probably be some sort of pathological case in an algorithm being used, or perhaps from a poorly chosen algorithm. The point being, it’s not clear yet, and to solve that requires understanding the problem, not effecting a needless rewrite in a new language.

[throwii]

> C is generally not the problem when it comes to performance issues in the kernel, which means rewriting that thing in Rust wouldn’t magically make it faster.

Agreed.

> The point being, it’s not clear yet, and to solve that requires understanding the problem, not effecting a needless rewrite in a new language.

Which is why the first question is why btrfs has issues others do not have. Some mention its CoW architecture, system design, too many features and not limiting storage to 90% and so increasing complexity. Others mention usual kernel issues.

Others mention that they had no issues to begin with and that its mixed reputation is unwarranted. I'm not clear who is right, but they are data points.

Thank you for your input in cautioning of rewrites to avoid needless work, I appreciate it.

[swinglock]

Btrfs is really only comparable to ZFS, which is also CoW, feature rich and written in C, but has been considered stable for a great many years.