Re: [PATCH 0/3] vmsplice: make vmsplice a trivial wrapper for preadv2/pwritev2

Linus Torvalds <[email protected]>
Newsgroups org.kernel.vger.linux-api,dev.linux.lists.patches,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel,org.kernel.vger.netdev,org.kvack.linux-mm
Message-ID <CAHk-=wgn3QTLj+F+XccE10dXY-UGWN8+fNLEvhsLw+tik9rOmg@mail.gmail.com>
On Wed, 3 Jun 2026 at 14:31, Andy Lutomirski <[email protected]> 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
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