// SPDX-License-Identifier: GPL-2.0-only
/*
 *	linux/mm/filemap.c
 *
 * Copyright (C) 1994-1999  Linus Torvalds
 */

/*
 * This file handles the generic file mmap semantics used by
 * most "normal" filesystems (but you don't /have/ to use this:
 * the NFS filesystem used to do this differently, for example)
 */

/* Extracted unchanged from Linux v6.0, mm/filemap.c:1599-1627.
 * Complete function definition; surrounding kernel context is required.
 * Source: https://github.com/torvalds/linux/blob/v6.0/mm/filemap.c#L1599
 * License text: GPL-2.0.txt (in this directory).
 */
void folio_end_writeback(struct folio *folio)
{
	/*
	 * folio_test_clear_reclaim() could be used here but it is an
	 * atomic operation and overkill in this particular case. Failing
	 * to shuffle a folio marked for immediate reclaim is too mild
	 * a gain to justify taking an atomic operation penalty at the
	 * end of every folio writeback.
	 */
	if (folio_test_reclaim(folio)) {
		folio_clear_reclaim(folio);
		folio_rotate_reclaimable(folio);
	}

	/*
	 * Writeback does not hold a folio reference of its own, relying
	 * on truncation to wait for the clearing of PG_writeback.
	 * But here we must make sure that the folio is not freed and
	 * reused before the folio_wake().
	 */
	folio_get(folio);
	if (!__folio_end_writeback(folio))
		BUG();

	smp_mb__after_atomic();
	folio_wake(folio, PG_writeback);
	acct_reclaim_writeback(folio);
	folio_put(folio);
}