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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Willem de Bruijn , David Ahern , 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 v7 04/16] tcp: Support MSG_SPLICE_PAGES Date: Mon, 15 May 2023 10:33:33 +0100 Message-Id: <20230515093345.396978-5-dhowells@redhat.com> In-Reply-To: <20230515093345.396978-1-dhowells@redhat.com> References: <20230515093345.396978-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Stat-Signature: e5ynx9zurcqbmuqkenbti4kwau5nf3os X-Rspam-User: X-Rspamd-Queue-Id: 09D1FA0010 X-Rspamd-Server: rspam07 X-HE-Tag: 1684143252-199513 X-HE-Meta: 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 Um4d10XJ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Make TCP's sendmsg() support MSG_SPLICE_PAGES. This causes pages to be spliced or copied (if it cannot be spliced) from the source iterator. This allows ->sendpage() to be replaced by something that can handle multiple multipage folios in a single transaction. Signed-off-by: David Howells cc: Eric Dumazet cc: "David S. Miller" cc: David Ahern cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- Notes: ver #7) - Missed a "zc = 1" in tcp_sendmsg_locked(). ver #6) - Set zc to 0/MSG_ZEROCOPY/MSG_SPLICE_PAGES rather than 0/1/2. - Use common helper. net/ipv4/tcp.c | 43 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 36 insertions(+), 7 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 4d6392c16b7a..026f483f42e3 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1223,7 +1223,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) int flags, err, copied = 0; int mss_now = 0, size_goal, copied_syn = 0; int process_backlog = 0; - bool zc = false; + int zc = 0; long timeo; flags = msg->msg_flags; @@ -1234,17 +1234,22 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) if (msg->msg_ubuf) { uarg = msg->msg_ubuf; net_zcopy_get(uarg); - zc = sk->sk_route_caps & NETIF_F_SG; + if (sk->sk_route_caps & NETIF_F_SG) + zc = MSG_ZEROCOPY; } else if (sock_flag(sk, SOCK_ZEROCOPY)) { uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb)); if (!uarg) { err = -ENOBUFS; goto out_err; } - zc = sk->sk_route_caps & NETIF_F_SG; - if (!zc) + if (sk->sk_route_caps & NETIF_F_SG) + zc = MSG_ZEROCOPY; + else uarg_to_msgzc(uarg)->zerocopy = 0; } + } else if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES) && size) { + if (sk->sk_route_caps & NETIF_F_SG) + zc = MSG_SPLICE_PAGES; } if (unlikely(flags & MSG_FASTOPEN || inet_sk(sk)->defer_connect) && @@ -1307,7 +1312,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) goto do_error; while (msg_data_left(msg)) { - int copy = 0; + ssize_t copy = 0; skb = tcp_write_queue_tail(sk); if (skb) @@ -1348,7 +1353,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) if (copy > msg_data_left(msg)) copy = msg_data_left(msg); - if (!zc) { + if (zc == 0) { bool merge = true; int i = skb_shinfo(skb)->nr_frags; struct page_frag *pfrag = sk_page_frag(sk); @@ -1393,7 +1398,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) page_ref_inc(pfrag->page); } pfrag->offset += copy; - } else { + } else if (zc == MSG_ZEROCOPY) { /* First append to a fragless skb builds initial * pure zerocopy skb */ @@ -1414,6 +1419,30 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) if (err < 0) goto do_error; copy = err; + } else if (zc == MSG_SPLICE_PAGES) { + /* Splice in data if we can; copy if we can't. */ + if (tcp_downgrade_zcopy_pure(sk, skb)) + goto wait_for_space; + copy = tcp_wmem_schedule(sk, copy); + if (!copy) + goto wait_for_space; + + err = skb_splice_from_iter(skb, &msg->msg_iter, copy, + sk->sk_allocation); + if (err < 0) { + if (err == -EMSGSIZE) { + tcp_mark_push(tp, skb); + goto new_segment; + } + goto do_error; + } + copy = err; + + if (!(flags & MSG_NO_SHARED_FRAGS)) + skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG; + + sk_wmem_queued_add(sk, copy); + sk_mem_charge(sk, copy); } if (!copied)