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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, Willem de Bruijn Subject: [RFC PATCH v2 04/48] net: Declare MSG_SPLICE_PAGES internal sendmsg() flag Date: Wed, 29 Mar 2023 15:13:10 +0100 Message-Id: <20230329141354.516864-5-dhowells@redhat.com> In-Reply-To: <20230329141354.516864-1-dhowells@redhat.com> References: <20230329141354.516864-1-dhowells@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: fcptmfcjg8zrwwupfi86co5bfeucxnfe X-Rspamd-Queue-Id: 2652CC0019 X-HE-Tag: 1680099256-673745 X-HE-Meta: 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 sCBoFrQz 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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: Declare MSG_SPLICE_PAGES, an internal sendmsg() flag, that hints to a network protocol that it should splice pages from the source iterator rather than copying the data if it can. This flag is added to a list that is cleared by sendmsg and recvmsg syscalls on entry. This is intended as a replacement for the ->sendpage() op, allowing a way to splice in several multipage folios in one go. Signed-off-by: David Howells cc: Willem de Bruijn cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- include/linux/socket.h | 3 +++ net/socket.c | 7 +++++++ 2 files changed, 10 insertions(+) diff --git a/include/linux/socket.h b/include/linux/socket.h index 13c3a237b9c9..c2fa0f800999 100644 --- a/include/linux/socket.h +++ b/include/linux/socket.h @@ -327,6 +327,7 @@ struct ucred { */ #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */ +#define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator in sendmsg() */ #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */ #define MSG_CMSG_CLOEXEC 0x40000000 /* Set close_on_exec for file descriptor received through @@ -337,6 +338,8 @@ struct ucred { #define MSG_CMSG_COMPAT 0 /* We never have 32 bit fixups */ #endif +/* Flags to be cleared on entry by sendmsg, recvmsg, sendmmsg and recvmmsg syscalls */ +#define MSG_INTERNAL_FLAGS (MSG_SPLICE_PAGES) /* Setsockoptions(2) level. Thanks to BSD these must match IPPROTO_xxx */ #define SOL_IP 0 diff --git a/net/socket.c b/net/socket.c index 6bae8ce7059e..dfb912bbed62 100644 --- a/net/socket.c +++ b/net/socket.c @@ -2139,6 +2139,7 @@ int __sys_sendto(int fd, void __user *buff, size_t len, unsigned int flags, msg.msg_name = (struct sockaddr *)&address; msg.msg_namelen = addr_len; } + flags &= ~MSG_INTERNAL_FLAGS; if (sock->file->f_flags & O_NONBLOCK) flags |= MSG_DONTWAIT; msg.msg_flags = flags; @@ -2192,6 +2193,7 @@ int __sys_recvfrom(int fd, void __user *ubuf, size_t size, unsigned int flags, if (!sock) goto out; + flags &= ~MSG_INTERNAL_FLAGS; if (sock->file->f_flags & O_NONBLOCK) flags |= MSG_DONTWAIT; err = sock_recvmsg(sock, &msg, flags); @@ -2579,6 +2581,7 @@ long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned int flags, if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT)) return -EINVAL; + flags &= ~MSG_INTERNAL_FLAGS; sock = sockfd_lookup_light(fd, &err, &fput_needed); if (!sock) @@ -2627,6 +2630,7 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, entry = mmsg; compat_entry = (struct compat_mmsghdr __user *)mmsg; err = 0; + flags &= ~MSG_INTERNAL_FLAGS; flags |= MSG_BATCH; while (datagrams < vlen) { @@ -2775,6 +2779,7 @@ long __sys_recvmsg_sock(struct socket *sock, struct msghdr *msg, struct user_msghdr __user *umsg, struct sockaddr __user *uaddr, unsigned int flags) { + flags &= ~MSG_INTERNAL_FLAGS; return ____sys_recvmsg(sock, msg, umsg, uaddr, flags, 0); } @@ -2787,6 +2792,7 @@ long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned int flags, if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT)) return -EINVAL; + flags &= ~MSG_INTERNAL_FLAGS; sock = sockfd_lookup_light(fd, &err, &fput_needed); if (!sock) @@ -2839,6 +2845,7 @@ static int do_recvmmsg(int fd, struct mmsghdr __user *mmsg, goto out_put; } } + flags &= ~MSG_INTERNAL_FLAGS; entry = mmsg; compat_entry = (struct compat_mmsghdr __user *)mmsg;