// SPDX-License-Identifier: GPL-2.0-only

/*
 * Official Linux v6.0: mm/util.c
 * https://github.com/torvalds/linux/blob/v6.0/mm/util.c#L799
 * Exact definition/declaration; not a reconstruction of a book listing.
 * See GPL-2.0.txt. Not a standalone translation unit.
 */

struct address_space *folio_mapping(struct folio *folio)
{
	struct address_space *mapping;

	/* This happens if someone calls flush_dcache_page on slab page */
	if (unlikely(folio_test_slab(folio)))
		return NULL;

	if (unlikely(folio_test_swapcache(folio)))
		return swap_address_space(folio_swap_entry(folio));

	mapping = folio->mapping;
	if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
		return NULL;

	return mapping;
}