diff mbox series

[v3,03/55] net: Declare MSG_SPLICE_PAGES internal sendmsg() flag

Message ID 20230331160914.1608208-4-dhowells@redhat.com
State New
Headers
Series splice, net: Replace sendpage with sendmsg(MSG_SPLICE_PAGES) |

Commit Message

David Howells March 31, 2023, 4:08 p.m. UTC 
  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 <dhowells@redhat.com>
cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: netdev@vger.kernel.org
---
 include/linux/socket.h | 3 +++
 net/socket.c           | 2 ++
 2 files changed, 5 insertions(+)

Comments

Willem de Bruijn April 2, 2023, 2:56 p.m. UTC | #1 
David Howells wrote:
> 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.

nit: comment not longer matches implementation: recvmsg
 
> 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 <dhowells@redhat.com>
> cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> cc: "David S. Miller" <davem@davemloft.net>
> cc: Eric Dumazet <edumazet@google.com>
> cc: Jakub Kicinski <kuba@kernel.org>
> cc: Paolo Abeni <pabeni@redhat.com>
> cc: Jens Axboe <axboe@kernel.dk>
> cc: Matthew Wilcox <willy@infradead.org>
> cc: netdev@vger.kernel.org

Aside from that

Reviewed-by: Willem de Bruijn <willemb@google.com>
diff mbox series

Patch

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 13c3a237b9c9..bd1cc3238851 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 and sendmmsg syscalls */
+#define MSG_INTERNAL_SENDMSG_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..0c39ce57d603 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_SENDMSG_FLAGS;
 	if (sock->file->f_flags & O_NONBLOCK)
 		flags |= MSG_DONTWAIT;
 	msg.msg_flags = flags;
@@ -2486,6 +2487,7 @@  static int ____sys_sendmsg(struct socket *sock, struct msghdr *msg_sys,
 	}
 	msg_sys->msg_flags = flags;
 
+	flags &= ~MSG_INTERNAL_SENDMSG_FLAGS;
 	if (sock->file->f_flags & O_NONBLOCK)
 		msg_sys->msg_flags |= MSG_DONTWAIT;
 	/*