From: Eric Dumazet <dada1-fPLkHRcR87vqlBn2x/YWAg@public.gmane.org>
Date: Thu, 27 Nov 2008 00:32:59 +0100

This function arms a flag (MNT_SPECIAL) on the vfs, to avoid
refcounting on permanent system vfs.
Use this function for sockets, pipes, anonymous fds.

(socket8 bench result : from 2.94s to 2.23s)

Signed-off-by: Eric Dumazet <dada1-fPLkHRcR87vqlBn2x/YWAg@public.gmane.org>

For networking bits:

Acked-by: David S. Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>