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net: Use sendmsg(MSG_SPLICE_PAGES) not sendpage in skb_send_sock()

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Use sendmsg() with MSG_SPLICE_PAGES rather than sendpage in
skb_send_sock().  This causes pages to be spliced from the source iterator
if possible.

This allows ->sendpage() to be replaced by something that can handle
multiple multipage folios in a single transaction.

Note that this could perhaps be improved to fill out a bvec array with all
the frags and then make a single sendmsg call, possibly sticking the header
on the front also.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Link: https://lore.kernel.org/r/20230623225513.2732256-3-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
David Howells 2023-06-23 23:54:59 +01:00 committed by Jakub Kicinski
parent f8dd95b29d
commit c729ed6f5b
1 changed files with 35 additions and 29 deletions
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64
net/core/skbuff.c
View File

@ -2989,32 +2989,32 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
}
EXPORT_SYMBOL_GPL(skb_splice_bits);
static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg,
struct kvec *vec, size_t num, size_t size)
static int sendmsg_locked(struct sock *sk, struct msghdr *msg)
{
struct socket *sock = sk->sk_socket;
size_t size = msg_data_left(msg);
if (!sock)
return -EINVAL;
if (!sock->ops->sendmsg_locked)
return sock_no_sendmsg_locked(sk, msg, size);
return sock->ops->sendmsg_locked(sk, msg, size);
}
static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg)
{
struct socket *sock = sk->sk_socket;
if (!sock)
return -EINVAL;
return kernel_sendmsg(sock, msg, vec, num, size);
return sock_sendmsg(sock, msg);
}
static int sendpage_unlocked(struct sock *sk, struct page *page, int offset,
size_t size, int flags)
{
struct socket *sock = sk->sk_socket;
if (!sock)
return -EINVAL;
return kernel_sendpage(sock, page, offset, size, flags);
}
typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg,
struct kvec *vec, size_t num, size_t size);
typedef int (*sendpage_func)(struct sock *sk, struct page *page, int offset,
size_t size, int flags);
typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg);
static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset,
int len, sendmsg_func sendmsg, sendpage_func sendpage)
int len, sendmsg_func sendmsg)
{
unsigned int orig_len = len;
struct sk_buff *head = skb;
@ -3034,8 +3034,9 @@ do_frag_list:
memset(&msg, 0, sizeof(msg));
msg.msg_flags = MSG_DONTWAIT;
ret = INDIRECT_CALL_2(sendmsg, kernel_sendmsg_locked,
sendmsg_unlocked, sk, &msg, &kv, 1, slen);
iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &kv, 1, slen);
ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
sendmsg_unlocked, sk, &msg);
if (ret <= 0)
goto error;
@ -3066,11 +3067,18 @@ do_frag_list:
slen = min_t(size_t, len, skb_frag_size(frag) - offset);
while (slen) {
ret = INDIRECT_CALL_2(sendpage, kernel_sendpage_locked,
sendpage_unlocked, sk,
skb_frag_page(frag),
skb_frag_off(frag) + offset,
slen, MSG_DONTWAIT);
struct bio_vec bvec;
struct msghdr msg = {
.msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT,
};
bvec_set_page(&bvec, skb_frag_page(frag), slen,
skb_frag_off(frag) + offset);
iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1,
slen);
ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked,
sendmsg_unlocked, sk, &msg);
if (ret <= 0)
goto error;
@ -3107,16 +3115,14 @@ error:
int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
int len)
{
return __skb_send_sock(sk, skb, offset, len, kernel_sendmsg_locked,
kernel_sendpage_locked);
return __skb_send_sock(sk, skb, offset, len, sendmsg_locked);
}
EXPORT_SYMBOL_GPL(skb_send_sock_locked);
/* Send skb data on a socket. Socket must be unlocked. */
int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len)
{
return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked,
sendpage_unlocked);
return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked);
}
/**