make skb_add_data,{_nocache}() and skb_copy_to_page_nocache() advance only on success

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/skbuff.h

@@ -2809,12 +2809,12 @@ static inline int skb_add_data(struct sk_buff *skb,
 
 	if (skb->ip_summed == CHECKSUM_NONE) {
 		__wsum csum = 0;
-		if (csum_and_copy_from_iter(skb_put(skb, copy), copy,
-					    &csum, from) == copy) {
+		if (csum_and_copy_from_iter_full(skb_put(skb, copy), copy,
+					         &csum, from)) {
 			skb->csum = csum_block_add(skb->csum, csum, off);
 			return 0;
 		}
-	} else if (copy_from_iter(skb_put(skb, copy), copy, from) == copy)
+	} else if (copy_from_iter_full(skb_put(skb, copy), copy, from))
 		return 0;
 
 	__skb_trim(skb, off);

include/net/sock.h

@@ -1783,13 +1783,13 @@ static inline int skb_do_copy_data_nocache(struct sock *sk, struct sk_buff *skb,
 {
 	if (skb->ip_summed == CHECKSUM_NONE) {
 		__wsum csum = 0;
-		if (csum_and_copy_from_iter(to, copy, &csum, from) != copy)
+		if (!csum_and_copy_from_iter_full(to, copy, &csum, from))
 			return -EFAULT;
 		skb->csum = csum_block_add(skb->csum, csum, offset);
 	} else if (sk->sk_route_caps & NETIF_F_NOCACHE_COPY) {
-		if (copy_from_iter_nocache(to, copy, from) != copy)
+		if (!copy_from_iter_full_nocache(to, copy, from))
 			return -EFAULT;
-	} else if (copy_from_iter(to, copy, from) != copy)
+	} else if (!copy_from_iter_full(to, copy, from))
 		return -EFAULT;
 
 	return 0;