Re: [fuse-devel] fuse zero copy

[Geert Custers <geert.aj.custers@gmail.com>]

> Actually it is being worked on.   Attaching the current
> proof-of-concept kernel patch for this.
> 
> I don't have a patch for libfuse yet, as I'm testing new ideas with a
> dummy filesystem that does raw /dev/fuse access.  Also attached, needs
> to be run with "-m" to enable the file mapping mode.

I looked at the patch and proof of concept filesystem. I imagine the
libfuse bindings would be relatively simple for this, something like a
fuse_map_fd(), fuse_unmap_fd() and then a map() in the fuse_ops struct.

> To make this more useful, the kernel would need to cache the mapping,
> so it doesn't need to issue a MAP request on each read.  That would
> also optimize the case of long extents, or files mirrored completely
> from an underlying filesystem (as done by the test program).

I have some spare time so I could write some patches for libfuse and try
add caching of the mapping on the kernel side. Maybe you can let me know
your thoughts on what this would look like, so we are on the same page.

Thanks,
Geert