Re: [RFC[RAP]] fuse: use fs-iomap for better performance so we can containerize ext4

Allison Karlitskaya
2025-06-20T08:58:53Z

hi Ted,

Sorry I didn't see this earlier. I've been travelling.

On Wed, 11 Jun 2025 at 21:25, Theodore Ts'o <tytso@mit.edu> wrote:
> This may break the github actions for composefs-rs[1], but I'm going
> to assume that they can figure out a way to transition to Fuse3
> (hopefully by just using a newer version of Ubuntu, but I suppose it's
> possible that Rust bindings only exist for Fuse2, and not Fuse3). But
> in any case, I don't think it makes sense to hold back fuse2fs
> development just for the sake of Ubuntu Focal (LTS 20.04). And if
> necessary, composefs-rs can just stay back on e2fsprogs 1.47.N until
> they can get off of Fuse2 and/or Ubuntu 20.04. Allison, does that
> sound fair to you?

To be honest, with a composefs-rs hat on, I don't care at all about
fuse support for ext2/3/4 (although I think it's cool that it exists).
We also use fuse in composefs-rs for unrelated reasons, but even there
we use the fuser rust crate which has a "pure rust" direct syscall
layer that no longer depends on libfuse. Our use of e2fsprogs is
strictly related to building testing images in CI, and for that we
only use mkfs.ext4. There's also no specific reason that we're using
old Ubuntu. I probably just copy-pasted it from another project
without paying too much attention.

Thanks for asking, though!

lis