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@xxxxxxxxxx>
cc: Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx>
cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
cc: Eric Dumazet <edumazet@xxxxxxxxxx>
cc: Jakub Kicinski <kuba@xxxxxxxxxx>
cc: Paolo Abeni <pabeni@xxxxxxxxxx>
cc: Jens Axboe <axboe@xxxxxxxxx>
cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
cc: netdev@xxxxxxxxxxxxxxx
---
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;
