CRED: Pass credentials through dentry_open()

Pass credentials through dentry_open() so that the COW creds patch can have
SELinux's flush_unauthorized_files() pass the appropriate creds back to itself
when it opens its null chardev.

The security_dentry_open() call also now takes a creds pointer, as does the
dentry_open hook in struct security_operations.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/fs/nfsctl.c b/fs/nfsctl.c
index aed8145..cc4ef26 100644
--- a/fs/nfsctl.c
+++ b/fs/nfsctl.c
@@ -41,7 +41,8 @@
 		error = may_open(&nd, MAY_WRITE, FMODE_WRITE);
 
 	if (!error)
-		return dentry_open(nd.path.dentry, nd.path.mnt, flags);
+		return dentry_open(nd.path.dentry, nd.path.mnt, flags,
+				   current_cred());
 
 	path_put(&nd.path);
 	return ERR_PTR(error);