[NET]: Add the helper kernel_sock_shutdown()

...and fix a couple of bugs in the NBD, CIFS and OCFS2 socket handlers.

Looking at the sock->op->shutdown() handlers, it looks as if all of them
take a SHUT_RD/SHUT_WR/SHUT_RDWR argument instead of the
RCV_SHUTDOWN/SEND_SHUTDOWN arguments.
Add a helper, and then define the SHUT_* enum to ensure that kernel users
of shutdown() don't get confused.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Mark Fasheh <mark.fasheh@oracle.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index 685c180..d84bd15 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -58,6 +58,7 @@
 #include <linux/slab.h>
 #include <linux/idr.h>
 #include <linux/kref.h>
+#include <linux/net.h>
 #include <net/tcp.h>
 
 #include <asm/uaccess.h>
@@ -616,8 +617,7 @@
 		del_timer_sync(&sc->sc_idle_timeout);
 		o2net_sc_cancel_delayed_work(sc, &sc->sc_keepalive_work);
 		sc_put(sc);
-		sc->sc_sock->ops->shutdown(sc->sc_sock,
-					   RCV_SHUTDOWN|SEND_SHUTDOWN);
+		kernel_sock_shutdown(sc->sc_sock, SHUT_RDWR);
 	}
 
 	/* not fatal so failed connects before the other guy has our