[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/drivers/block/nbd.c b/drivers/block/nbd.c
index 6332aca..b4c0888 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -28,6 +28,7 @@
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <net/sock.h>
+#include <linux/net.h>
 
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -126,7 +127,7 @@
 	if (lo->sock) {
 		printk(KERN_WARNING "%s: shutting down socket\n",
 			lo->disk->disk_name);
-		lo->sock->ops->shutdown(lo->sock, SEND_SHUTDOWN|RCV_SHUTDOWN);
+		kernel_sock_shutdown(lo->sock, SHUT_RDWR);
 		lo->sock = NULL;
 	}
 	if (lock)