// 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:926-951.
 * Complete function definition; surrounding kernel context is required.
 * Source: https://github.com/torvalds/linux/blob/v6.0/mm/filemap.c#L926
 * License text: GPL-2.0.txt (in this directory).
 */
int filemap_add_folio(struct address_space *mapping, struct folio *folio,
				pgoff_t index, gfp_t gfp)
{
	void *shadow = NULL;
	int ret;

	__folio_set_locked(folio);
	ret = __filemap_add_folio(mapping, folio, index, gfp, &shadow);
	if (unlikely(ret))
		__folio_clear_locked(folio);
	else {
		/*
		 * The folio might have been evicted from cache only
		 * recently, in which case it should be activated like
		 * any other repeatedly accessed folio.
		 * The exception is folios getting rewritten; evicting other
		 * data from the working set, only to cache data that will
		 * get overwritten with something else, is a waste of memory.
		 */
		WARN_ON_ONCE(folio_test_active(folio));
		if (!(gfp & __GFP_WRITE) && shadow)
			workingset_refault(folio, shadow);
		folio_add_lru(folio);
	}
	return ret;
}