net: skbuff: add skb_append_pagefrags and use it

Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -861,6 +861,9 @@ int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
 					int len, int odd, struct sk_buff *skb),
 			    void *from, int length);
 
+int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
+			 int offset, size_t size);
+
 struct skb_seq_state {
 	__u32		lower_offset;
 	__u32		upper_offset;

net/core/skbuff.c

@@ -2915,6 +2915,24 @@ int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
 }
 EXPORT_SYMBOL(skb_append_datato_frags);
 
+int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
+			 int offset, size_t size)
+{
+	int i = skb_shinfo(skb)->nr_frags;
+
+	if (skb_can_coalesce(skb, i, page, offset)) {
+		skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
+	} else if (i < MAX_SKB_FRAGS) {
+		get_page(page);
+		skb_fill_page_desc(skb, i, page, offset, size);
+	} else {
+		return -EMSGSIZE;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(skb_append_pagefrags);
+
 /**
  *	skb_pull_rcsum - pull skb and update receive checksum
  *	@skb: buffer to update

net/ipv4/ip_output.c

@@ -1233,11 +1233,9 @@ ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
 	}
 
 	while (size > 0) {
-		int i;
-
-		if (skb_is_gso(skb))
+		if (skb_is_gso(skb)) {
 			len = size;
-		else {
+		} else {
 
 			/* Check if the remaining data fits into current packet. */
 			len = mtu - skb->len;
@@ -1289,15 +1287,10 @@ ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
 			continue;
 		}
 
-		i = skb_shinfo(skb)->nr_frags;
 		if (len > size)
 			len = size;
-		if (skb_can_coalesce(skb, i, page, offset)) {
-			skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
-		} else if (i < MAX_SKB_FRAGS) {
-			get_page(page);
-			skb_fill_page_desc(skb, i, page, offset, len);
-		} else {
+
+		if (skb_append_pagefrags(skb, page, offset, len)) {
 			err = -EMSGSIZE;
 			goto error;
 		}