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

Bernd Schubert
2025-06-20T11:50:24Z

On 6/20/25 10:58, Allison Karlitskaya wrote:
> 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.

From libfuse point of view I'm too happy about that split into different
libraries. Libfuse already right now misses several features because
they were added to virtiofs, but not to libfuse. I need to find the time
for it, but I guess it makes sense to add rust support to libfuse (and
some parts can be entirely rewritten into rust).

Thanks,
Bernd