Convert obvious places to deactivate_locked_super()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 63a4a59..21165cf 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -389,11 +389,10 @@
 	return 0;
 
 out_dput:
-	dput(s->s_root);
+	dput(s->s_root); /* undo dget() in simple_set_mnt() */
 
 out_undo_sget:
-	up_write(&s->s_umount);
-	deactivate_super(s);
+	deactivate_locked_super(s);
 	return error;
 }