ovl_dentry_has_upper_alias
if (!err && parent && !ovl_dentry_has_upper_alias(dentry))
bool ovl_dentry_has_upper_alias(struct dentry *dentry);
if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) {
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&
(ovl_dentry_has_upper_alias(dentry) || disconnected) &&