extern int skb_copy_datagram_iovec(const struct sk_buff *from,
int offset, struct iovec *to,
int size);
extern int skb_copy_and_csum_datagram(const struct sk_buff *skb,
extern int skb_copy_datagram_iovec(const struct sk_buff *from,
int offset, struct iovec *to,
int size);
extern int skb_copy_and_csum_datagram(const struct sk_buff *skb,