Blacklist items binded as readonly

fs/fs.go

@@ -226,6 +226,9 @@ func (fs *Filesystem) blacklist(target string) error {
 	if err := syscall.Mount(fs.absPath(src), fs.absPath(t), "", syscall.MS_BIND, "mode=400,gid=0"); err != nil {
 		return fmt.Errorf("failed to bind %s -> %s for blacklist: %v", src, t, err)
 	}
+	if err := remount(fs.absPath(t), syscall.MS_RDONLY); err != nil {
+		return fmt.Errorf("failed to bind %s -> %s for blacklist: %v", src, t, err)
+	}
 	return nil
 }