From nobody Wed Feb 11 08:11:35 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 69176C761AF for ; Wed, 5 Apr 2023 16:58:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233279AbjDEQ6V (ORCPT ); Wed, 5 Apr 2023 12:58:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233664AbjDEQ4w (ORCPT ); Wed, 5 Apr 2023 12:56:52 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17F237281 for ; Wed, 5 Apr 2023 09:54:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680713683; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4DKKh1jysgamxWGpEyeqRE19EsYVOUgugB+w/Q3Uqtg=; b=goka7qCHd27EjsRG2dIG9oPALnsAN810wybe4spYYhHETi74W2KMqAbI0TTA1/N5SfVCQc JdsKKac2CxzO9I2Gyecf4GQIgCn85UPdXRKZBVPdii4OHWjsO06+ybM4Ey3K5VSKHyN2UD D2dGJHDaNH/0eJG3A8hJcz2I524CtSU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-547-cweTzd3XPYSIW2fcQ6DILQ-1; Wed, 05 Apr 2023 12:54:40 -0400 X-MC-Unique: cweTzd3XPYSIW2fcQ6DILQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5B889885624; Wed, 5 Apr 2023 16:54:39 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id 54D9CC1602A; Wed, 5 Apr 2023 16:54:37 +0000 (UTC) From: David Howells To: netdev@vger.kernel.org Cc: David Howells , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Willem de Bruijn , Matthew Wilcox , Al Viro , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH net-next v4 19/20] af_unix: Support MSG_SPLICE_PAGES Date: Wed, 5 Apr 2023 17:53:38 +0100 Message-Id: <20230405165339.3468808-20-dhowells@redhat.com> In-Reply-To: <20230405165339.3468808-1-dhowells@redhat.com> References: <20230405165339.3468808-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Make AF_UNIX sendmsg() support MSG_SPLICE_PAGES, splicing in pages from the source iterator if possible and copying the data in otherwise. This allows ->sendpage() to be replaced by something that can handle multiple multipage folios in a single transaction. Signed-off-by: David Howells cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- net/unix/af_unix.c | 93 ++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 77 insertions(+), 16 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index fb31e8a4409e..fee431a089d3 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2157,6 +2157,53 @@ static int queue_oob(struct socket *sock, struct msg= hdr *msg, struct sock *other } #endif =20 +/* + * Extract pages from an iterator and add them to the socket buffer. + */ +static ssize_t unix_extract_bvec_to_skb(struct sk_buff *skb, + struct iov_iter *iter, ssize_t maxsize) +{ + struct page *pages[8], **ppages =3D pages; + unsigned int i, nr; + ssize_t ret =3D 0; + + while (iter->count > 0) { + size_t off, len; + + nr =3D min_t(size_t, MAX_SKB_FRAGS - skb_shinfo(skb)->nr_frags, + ARRAY_SIZE(pages)); + if (nr =3D=3D 0) + break; + + len =3D iov_iter_extract_pages(iter, &ppages, maxsize, nr, 0, &off); + if (len <=3D 0) { + if (!ret) + ret =3D len ?: -EIO; + break; + } + + i =3D 0; + do { + size_t part =3D min_t(size_t, PAGE_SIZE - off, len); + + if (skb_append_pagefrags(skb, pages[i++], off, part) < 0) { + if (!ret) + ret =3D -EMSGSIZE; + goto out; + } + off =3D 0; + ret +=3D part; + maxsize -=3D part; + len -=3D part; + } while (len > 0); + if (maxsize <=3D 0) + break; + } + +out: + return ret; +} + static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) { @@ -2200,19 +2247,25 @@ static int unix_stream_sendmsg(struct socket *sock,= struct msghdr *msg, while (sent < len) { size =3D len - sent; =20 - /* Keep two messages in the pipe so it schedules better */ - size =3D min_t(int, size, (sk->sk_sndbuf >> 1) - 64); + if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) { + skb =3D sock_alloc_send_pskb(sk, 0, 0, + msg->msg_flags & MSG_DONTWAIT, + &err, 0); + } else { + /* Keep two messages in the pipe so it schedules better */ + size =3D min_t(int, size, (sk->sk_sndbuf >> 1) - 64); =20 - /* allow fallback to order-0 allocations */ - size =3D min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ); + /* allow fallback to order-0 allocations */ + size =3D min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ); =20 - data_len =3D max_t(int, 0, size - SKB_MAX_HEAD(0)); + data_len =3D max_t(int, 0, size - SKB_MAX_HEAD(0)); =20 - data_len =3D min_t(size_t, size, PAGE_ALIGN(data_len)); + data_len =3D min_t(size_t, size, PAGE_ALIGN(data_len)); =20 - skb =3D sock_alloc_send_pskb(sk, size - data_len, data_len, - msg->msg_flags & MSG_DONTWAIT, &err, - get_order(UNIX_SKB_FRAGS_SZ)); + skb =3D sock_alloc_send_pskb(sk, size - data_len, data_len, + msg->msg_flags & MSG_DONTWAIT, &err, + get_order(UNIX_SKB_FRAGS_SZ)); + } if (!skb) goto out_err; =20 @@ -2224,13 +2277,21 @@ static int unix_stream_sendmsg(struct socket *sock,= struct msghdr *msg, } fds_sent =3D true; =20 - skb_put(skb, size - data_len); - skb->data_len =3D data_len; - skb->len =3D size; - err =3D skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size); - if (err) { - kfree_skb(skb); - goto out_err; + if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) { + size =3D unix_extract_bvec_to_skb(skb, &msg->msg_iter, size); + skb->data_len +=3D size; + skb->len +=3D size; + skb->truesize +=3D size; + refcount_add(size, &sk->sk_wmem_alloc); + } else { + skb_put(skb, size - data_len); + skb->data_len =3D data_len; + skb->len =3D size; + err =3D skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size); + if (err) { + kfree_skb(skb); + goto out_err; + } } =20 unix_state_lock(other);