Convert obvious places to deactivate_locked_super()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/libfs.c b/fs/libfs.c
index cd22319..80046dd 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -246,8 +246,7 @@
 	return 0;
 
 Enomem:
-	up_write(&s->s_umount);
-	deactivate_super(s);
+	deactivate_locked_super(s);
 	return -ENOMEM;
 }