// SPDX-License-Identifier: GPL-2.0-only
/*
 * Complete definition from Linux v6.18 mm/filemap.c.
 * Source: https://github.com/torvalds/linux/blob/v6.18/mm/filemap.c
 * Copyright (C) 1994-1999  Linus Torvalds
 * Kernel excerpt; not a standalone user-space program.
 * The book's exact source tag is not asserted.
 */

void folio_unlock(struct folio *folio)
{
	/* Bit 7 allows x86 to check the byte's sign bit */
	BUILD_BUG_ON(PG_waiters != 7);
	BUILD_BUG_ON(PG_locked > 7);
	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
	if (folio_xor_flags_has_waiters(folio, 1 << PG_locked))
		folio_wake_bit(folio, PG_locked);
}