[NET] skbuff: Add skb_cow_head

This patch adds an optimised version of skb_cow that avoids the copy if
the header can be modified even if the rest of the payload is cloned.

This can be used in encapsulating paths where we only need to modify the
header.  As it is, this can be used in PPPOE and bridging.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index 3ee2022928e3..fc13130035e7 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -183,7 +183,7 @@ int nf_bridge_copy_header(struct sk_buff *skb)
         int err;
         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 
-        err = skb_cow(skb, header_size);
+        err = skb_cow_head(skb, header_size);
         if (err)
                 return err;