// SPDX-License-Identifier: GPL-2.0-only
/*
 * Complete scope from Linux v6.18 mm/backing-dev.c.
 * Source: https://github.com/torvalds/linux/blob/v6.18/mm/backing-dev.c
 * Kernel excerpt; not a standalone program.
 * The book exact source tag is not asserted.
 */

static void wb_shutdown(struct bdi_writeback *wb)
{
	/* Make sure nobody queues further work */
	spin_lock_irq(&wb->work_lock);
	if (!test_and_clear_bit(WB_registered, &wb->state)) {
		spin_unlock_irq(&wb->work_lock);
		return;
	}
	spin_unlock_irq(&wb->work_lock);

	cgwb_remove_from_bdi_list(wb);
	/*
	 * Drain work list and shutdown the delayed_work.  !WB_registered
	 * tells wb_workfn() that @wb is dying and its work_list needs to
	 * be drained no matter what.
	 */
	mod_delayed_work(bdi_wq, &wb->dwork, 0);
	flush_delayed_work(&wb->dwork);
	WARN_ON(!list_empty(&wb->work_list));
	flush_delayed_work(&wb->bw_dwork);
}