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From:   David Howells <dhowells@redhat.com>
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To:     Jakub Kicinski <kuba@kernel.org>
Cc:     dhowells@redhat.com, Eric Dumazet <edumazet@google.com>,
        netdev@vger.kernel.org,
        Alexander Duyck <alexander.duyck@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Paolo Abeni <pabeni@redhat.com>,
        Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        David Ahern <dsahern@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Jens Axboe <axboe@kernel.dk>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Menglong Dong <imagedong@tencent.com>
Subject: Re: [PATCH net-next v3 01/18] net: Copy slab data for sendmsg(MSG_SPLICE_PAGES)
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Date:   Fri, 23 Jun 2023 10:08:18 +0100
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Jakub Kicinski <kuba@kernel.org> wrote:

> If we can't reach instant agreement --
> can you strategically separate out the minimal set of changes required
> to just kill MSG_SENDPAGE_NOTLAST. IMHO it's worth getting that into
> 6.5.

Paolo Abeni <pabeni@redhat.com> wrote:

> Given all the above, and the late stage of the current devel cycle,
> would you consider slicing down this series to just kill
> MSG_SENDPAGE_NOTLAST, as Jakub suggested?

I could do that.

There is also another alternative.  I could just push the sendpage wrappers up
the stack into the higher-level callers.  Basically this:

int udp_sendpage(struct sock *sk, struct page *page, int offset,
		 size_t size, int flags)
{
	struct bio_vec bvec;
	struct msghdr msg = { .msg_flags = flags | MSG_SPLICE_PAGES };

	if (flags & MSG_SENDPAGE_NOTLAST)
		msg.msg_flags |= MSG_MORE;

	bvec_set_page(&bvec, page, size, offset);
	iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
	return udp_sendmsg(sk, &msg, size);
}

and kill off sendpage and MSG_SENDPAGE_NOTLAST.

David