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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 v6 07/18] tcp: Support MSG_SPLICE_PAGES Date: Tue, 11 Apr 2023 17:08:51 +0100 Message-Id: <20230411160902.4134381-8-dhowells@redhat.com> In-Reply-To: <20230411160902.4134381-1-dhowells@redhat.com> References: <20230411160902.4134381-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: 4rhap5i87pttpjjk7c6ok8zaokruiybm X-Rspamd-Queue-Id: 647D540026 X-HE-Tag: 1681229377-286266 X-HE-Meta: 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 ZLZ+CLR6 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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 #6) - 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 fd68d49490f2..0b2213da5aaf 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1221,7 +1221,7 @@ 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; @@ -1232,17 +1232,22 @@ 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 = 1; } 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) && @@ -1305,7 +1310,7 @@ 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) @@ -1346,7 +1351,7 @@ 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); @@ -1391,7 +1396,7 @@ 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 */ @@ -1412,6 +1417,30 @@ 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)