Re: [RFC[RAP] V2] fuse: use fs-iomap for better performance so we can containerize ext4

Darrick J. Wong
2025-07-01T06:05:27Z

On Mon, Jun 23, 2025 at 03:16:53PM +0200, Miklos Szeredi wrote:
> On Fri, 13 Jun 2025 at 19:37, Darrick J. Wong <djwong@kernel.org> wrote:
>
> > Top of that list is timestamps and file attributes, because fuse no
> > longer calls the fuse server for file writes. As a result, the kernel
> > inode always has the most uptodate versions of the some file attributes
> > (i_size, timestamps, mode) and just want to send FUSE_SETATTR whenever
> > the dirty inode gets flushed.
>
> This is already the case for cached writes, no new code should be needed.

Are you talking about the fc->writeback_cache stuff? Yeah, that mostly
works out for fuse2fs. Though I was wondering, when does atime get
updated? fs/fuse sets S_NOATIME, so I guess it's up to the fuse server
to update it when it wants to, and a later FUSE_GETATTR can pick it up?
If so, how do fuse servers implement lazytime/relatime?

--D

> Thanks,
> Miklos
>