static void io_file_data_ref_zero(struct percpu_ref *ref)
{
	struct fixed_file_data *data;

	data = container_of(ref, struct fixed_file_data, refs);

	/*
	 * We can't safely switch from inside this context, punt to wq. If
	 * the table ref is going away, the table is being unregistered.
	 * Don't queue up the async work for that case, the caller will
	 * handle it.
	 */
	if (!percpu_ref_is_dying(&data->refs))
		queue_work(system_wq, &data->ref_work);
}
static void io_file_data_ref_zero(struct percpu_ref *ref)
{
	struct fixed_file_data *data;

	data = container_of(ref, struct fixed_file_data, refs);

	 
	if (!percpu_ref_is_dying(&data->refs))
		queue_work(system_wq, &data->ref_work);
}