// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  Swap reorganised 29.12.95, Stephen Tweedie.
 *  kswapd added: 7.1.96  sct
 *  Removed kswapd_ctl limits, and swap out as many pages as needed
 *  to bring the system back to freepages.high: 2.4.97, Rik van Riel.
 *  Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
 *  Multiqueue VM started 5.8.00, Rik van Riel.
 */

/* Extracted unchanged from Linux v6.18, mm/vmscan.c:647-678.
 * Complete function definition; surrounding kernel context is required.
 * Source: https://github.com/torvalds/linux/blob/v6.18/mm/vmscan.c#L647
 * License text: GPL-2.0.txt (in this directory).
 */
static pageout_t writeout(struct folio *folio, struct address_space *mapping,
		struct swap_iocb **plug, struct list_head *folio_list)
{
	int res;

	folio_set_reclaim(folio);

	/*
	 * The large shmem folio can be split if CONFIG_THP_SWAP is not enabled
	 * or we failed to allocate contiguous swap entries, in which case
	 * the split out folios get added back to folio_list.
	 */
	if (shmem_mapping(mapping))
		res = shmem_writeout(folio, plug, folio_list);
	else
		res = swap_writeout(folio, plug);

	if (res < 0)
		handle_write_error(mapping, folio, res);
	if (res == AOP_WRITEPAGE_ACTIVATE) {
		folio_clear_reclaim(folio);
		return PAGE_ACTIVATE;
	}

	/* synchronous write? */
	if (!folio_test_writeback(folio))
		folio_clear_reclaim(folio);

	trace_mm_vmscan_write_folio(folio);
	node_stat_add_folio(folio, NR_VMSCAN_WRITE);
	return PAGE_SUCCESS;
}