net: Introduce skb_copy_datagram_from_iter_full()

In a similar manner to copy_from_iter()/copy_from_iter_full(), introduce
skb_copy_datagram_from_iter_full() which reverts the iterator to its
initial state when returning an error.

A subsequent fix for a vsock regression will make use of this new
function.

Cc: Christian Brauner <brauner@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Link: https://patch.msgid.link/20250818180355.29275-2-will@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 14b923ddb6dfcc3c031a7c9e4cb5fc4171424616..fa633657e4c068f2484086126fe25d50674e21cc 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4172,6 +4172,8 @@ int skb_copy_and_crc32c_datagram_iter(const struct sk_buff *skb, int offset,
                                      struct iov_iter *to, int len, u32 *crcp);
 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
                                 struct iov_iter *from, int len);
+int skb_copy_datagram_from_iter_full(struct sk_buff *skb, int offset,
+                                    struct iov_iter *from, int len);
 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 94cc4705e91da6ba6629ae469ae6507e9c6fdae9..f474b9b120f984c9e013abfbc4b68984b8a3a6d8 100644 (file)
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -618,6 +618,20 @@ fault:
 }
 EXPORT_SYMBOL(skb_copy_datagram_from_iter);
 
+int skb_copy_datagram_from_iter_full(struct sk_buff *skb, int offset,
+                                    struct iov_iter *from, int len)
+{
+       struct iov_iter_state state;
+       int ret;
+
+       iov_iter_save_state(from, &state);
+       ret = skb_copy_datagram_from_iter(skb, offset, from, len);
+       if (ret)
+               iov_iter_restore(from, &state);
+       return ret;
+}
+EXPORT_SYMBOL(skb_copy_datagram_from_iter_full);
+
 int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
                                struct iov_iter *from, size_t length)
 {