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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: David Howells , Al Viro , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 07/55] tcp: Support MSG_SPLICE_PAGES Date: Fri, 31 Mar 2023 17:08:26 +0100 Message-Id: <20230331160914.1608208-8-dhowells@redhat.com> In-Reply-To: <20230331160914.1608208-1-dhowells@redhat.com> References: <20230331160914.1608208-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Rspamd-Queue-Id: 3F13520029 X-Stat-Signature: fc8m9prxqgfepxjfnxw1db44h5rsd65k X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1680278986-718454 X-HE-Meta: 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 LYVpXb2B vQMBYiSJ5wCYmdrAtdQevd9jRwKcCYG+bDI0Y0HD0oO7BVdTh7BaZXgIp/2gb82Nffh8rUtnwDRlTrf1gVkfVrSKJLkR1UZDMdI3+8oATXeEgxj8Eds9dGWM9EnQHghgpMw1CPca0IRi7Mp8GFXDP63eS1EeBIPhnt5R2nlpq7abU8OKllRPN38M68fkH7DnGd9ohkpl9wi4g7yfMHIoONzyKYTh1PXrjipMUXFr9ywg3/J9lD5T7ELi5yPVL+rm5DDpw9dbPs6sqULbk5nqR2p5jYeZJ4PU8WMRn/sPxd+VsWtiV6RkXyEcBVxg1dd0SDjCmWyZm8vt4DyQWQO+5AZARoTNMF2akN9JgOPnicPm0OvR5wXXwLEMd2VuAYfu39TjMcWOIXG/bURcXUgt6ct4M76Yi3sUOZ0I8GJUV4J8iryh6WHE9ZexgWjDWQ2kalCRq 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 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: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- net/ipv4/tcp.c | 67 ++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 60 insertions(+), 7 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 288693981b00..910b327c236e 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1220,7 +1220,7 @@ 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; @@ -1231,17 +1231,22 @@ 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 = 1; + 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 = 2; } if (unlikely(flags & MSG_FASTOPEN || inet_sk(sk)->defer_connect) && @@ -1304,7 +1309,7 @@ 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) @@ -1345,7 +1350,7 @@ 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); @@ -1390,7 +1395,7 @@ 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 == 1) { /* First append to a fragless skb builds initial * pure zerocopy skb */ @@ -1411,6 +1416,54 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) if (err < 0) goto do_error; copy = err; + } else if (zc == 2) { + /* Splice in data. */ + struct page *page = NULL, **pages = &page; + size_t off = 0, part; + bool can_coalesce; + int i = skb_shinfo(skb)->nr_frags; + + copy = iov_iter_extract_pages(&msg->msg_iter, &pages, + copy, 1, 0, &off); + if (copy <= 0) { + err = copy ?: -EIO; + goto do_error; + } + + can_coalesce = skb_can_coalesce(skb, i, page, off); + if (!can_coalesce && i >= READ_ONCE(sysctl_max_skb_frags)) { + tcp_mark_push(tp, skb); + iov_iter_revert(&msg->msg_iter, copy); + goto new_segment; + } + if (tcp_downgrade_zcopy_pure(sk, skb)) { + iov_iter_revert(&msg->msg_iter, copy); + goto wait_for_space; + } + + part = tcp_wmem_schedule(sk, copy); + iov_iter_revert(&msg->msg_iter, copy - part); + if (!part) + goto wait_for_space; + copy = part; + + if (can_coalesce) { + skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); + } else { + get_page(page); + skb_fill_page_desc_noacc(skb, i, page, off, copy); + } + page = NULL; + + if (!(flags & MSG_NO_SHARED_FRAGS)) + skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG; + + skb->len += copy; + skb->data_len += copy; + skb->truesize += copy; + sk_wmem_queued_add(sk, copy); + sk_mem_charge(sk, copy); + } if (!copied)