On Wed, 3 Jun 2026 at 14:31, Andy Lutomirski [off-list ref] wrote:

I think I buried the lede too much and you're arguing against what I
was trying not to say.

Maybe we should keep an API that does an optimized copy, from one fd
to another, that can send from a file to the network with at most ONE
cpu-side copy.  Not aiming for zero like sendfile / splice.  Aiming
for one.

Oh, absolutely - that's what my completely untested test patch  basically did.

The user space interface was still there.

And the networking side still continued to use the ->splice_write()
thing for writing to the socket.

It was just the filesystem side that basically now instead of exposing
the page cache directly (with filemap_splice_read) now only exposed a
*copy* of the page cache (with copy_splice_read).

                  Linus