Add i_mutex ordering annotations to the sunrpc rpc_pipe code.  This code has 3
levels of i_mutex hierarchy in some cases: parent dir, client dir and file
inside client dir; the i_mutex ordering is I_MUTEX_PARENT -> I_MUTEX_CHILD ->
I_MUTEX_NORMAL

This patch applies this ordering annotation to the various functions.  This is
in line with the VFS expected ordering where it is always OK to lock a child
after locking a parent; the sunrpc code is very diligent in doing this
correctly.

Has no effect on non-lockdep kernels.
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>