Here is a patch that replaces all occurrences of dst_pmtu in the TCP
stack.  As a result we no longer need ext2_header_len.

This has a nice synergetic effect with Arnaldo's latest change to
linux/tcp.h :)

I'll be removing other users of dst->path/dst_pmtu next.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>