Make IP/UDP sendmsg() support MSG_SPLICE_PAGES. This causes pages to be
spliced from the source iterator.
This allows ->sendpage() to be replaced by something that can handle
multiple multipage folios in a single transaction.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx>
cc: David Ahern <dsahern@xxxxxxxxxx>
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
---
Notes:
ver #6)
- Use common helper.
net/ipv4/ip_output.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 52fc840898d8..c7db973b5d29 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1048,6 +1048,14 @@ static int __ip_append_data(struct sock *sk,
skb_zcopy_set(skb, uarg, &extra_uref);
}
}
+ } else if ((flags & MSG_SPLICE_PAGES) && length) {
+ if (inet->hdrincl)
+ return -EPERM;
+ if (rt->dst.dev->features & NETIF_F_SG)
+ /* We need an empty buffer to attach stuff to */
+ paged = true;
+ else
+ flags &= ~MSG_SPLICE_PAGES;
}
cork->length += length;
@@ -1207,6 +1215,15 @@ static int __ip_append_data(struct sock *sk,
err = -EFAULT;
goto error;
}
+ } else if (flags & MSG_SPLICE_PAGES) {
+ struct msghdr *msg = from;
+
+ err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
+ sk->sk_allocation);
+ if (err < 0)
+ goto error;
+ copy = err;
+ wmem_alloc_delta += copy;
} else if (!zc) {
int i = skb_shinfo(skb)->nr_frags;
