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af_unix: Support MSG_SPLICE_PAGES 

Make AF_UNIX sendmsg() support MSG_SPLICE_PAGES, splicing in pages from the
source iterator if possible and copying the data in otherwise.

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

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Kuniyuki Iwashima <kuniyu@amazon.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
David Howells 2023-05-22 13:11:24 +01:00 committed by Jakub Kicinski
parent c49cf26632
commit a0dbf5f818
1 changed files with 33 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
net/unix/af_unix.c
View File

@ -2200,19 +2200,25 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
while (sent < len) {
size = len - sent;
/* Keep two messages in the pipe so it schedules better */
size = min_t(int, size, (sk->sk_sndbuf >> 1) - 64);
if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) {
skb = sock_alloc_send_pskb(sk, 0, 0,
msg->msg_flags & MSG_DONTWAIT,
&err, 0);
} else {
/* Keep two messages in the pipe so it schedules better */
size = min_t(int, size, (sk->sk_sndbuf >> 1) - 64);
/* allow fallback to order-0 allocations */
size = min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ);
/* allow fallback to order-0 allocations */
size = min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ);
data_len = max_t(int, 0, size - SKB_MAX_HEAD(0));
data_len = max_t(int, 0, size - SKB_MAX_HEAD(0));
data_len = min_t(size_t, size, PAGE_ALIGN(data_len));
data_len = min_t(size_t, size, PAGE_ALIGN(data_len));
skb = sock_alloc_send_pskb(sk, size - data_len, data_len,
msg->msg_flags & MSG_DONTWAIT, &err,
get_order(UNIX_SKB_FRAGS_SZ));
skb = sock_alloc_send_pskb(sk, size - data_len, data_len,
msg->msg_flags & MSG_DONTWAIT, &err,
get_order(UNIX_SKB_FRAGS_SZ));
}
if (!skb)
goto out_err;
@ -2224,13 +2230,24 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
}
fds_sent = true;
skb_put(skb, size - data_len);
skb->data_len = data_len;
skb->len = size;
err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size);
if (err) {
kfree_skb(skb);
goto out_err;
if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) {
err = skb_splice_from_iter(skb, &msg->msg_iter, size,
sk->sk_allocation);
if (err < 0) {
kfree_skb(skb);
goto out_err;
}
size = err;
refcount_add(size, &sk->sk_wmem_alloc);
} else {
skb_put(skb, size - data_len);
skb->data_len = data_len;
skb->len = size;
err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size);
if (err) {
kfree_skb(skb);
goto out_err;
}
}
unix_state_lock(other);