linux-master/mm/readahead.c

193  * @ractl: Readahead control.
205 void page_cache_ra_unbounded(struct readahead_control *ractl,
208 	struct address_space *mapping = ractl->mapping;
209 	unsigned long index = readahead_index(ractl);
242 			read_pages(ractl);
243 			ractl->_index++;
244 			i = ractl->_index + ractl->_nr_pages - index - 1;
257 			read_pages(ractl);
258 			ractl->_index++;
259 			i = ractl->_index + ractl->_nr_pages - index - 1;
264 		ractl->_workingset |= folio_test_workingset(folio);
265 		ractl->_nr_pages++;
273 	read_pages(ractl);
285 static void do_page_cache_ra(struct readahead_control *ractl,
288 	struct inode *inode = ractl->mapping->host;
289 	unsigned long index = readahead_index(ractl);
303 	page_cache_ra_unbounded(ractl, nr_to_read, lookahead_size);
310 void force_page_cache_ra(struct readahead_control *ractl,
313 	struct address_space *mapping = ractl->mapping;
314 	struct file_ra_state *ra = ractl->ra;
325 	index = readahead_index(ractl);
333 		ractl->_index = index;
334 		do_page_cache_ra(ractl, this_chunk, 0);
468 static inline int ra_alloc_folio(struct readahead_control *ractl, pgoff_t index,
479 	err = filemap_add_folio(ractl->mapping, folio, index, gfp);
485 	ractl->_nr_pages += 1UL << order;
486 	ractl->_workingset |= folio_test_workingset(folio);
490 void page_cache_ra_order(struct readahead_control *ractl,
493 	struct address_space *mapping = ractl->mapping;
494 	pgoff_t index = readahead_index(ractl);
524 		err = ra_alloc_folio(ractl, index, mark, order, gfp);
535 	read_pages(ractl);
547 	do_page_cache_ra(ractl, ra->size, ra->async_size);
553 static void ondemand_readahead(struct readahead_control *ractl,
556 	struct backing_dev_info *bdi = inode_to_bdi(ractl->mapping->host);
557 	struct file_ra_state *ra = ractl->ra;
560 	pgoff_t index = readahead_index(ractl);
600 		start = page_cache_next_miss(ractl->mapping, index + 1,
634 	if (try_context_readahead(ractl->mapping, ra, index, req_size,
642 	do_page_cache_ra(ractl, req_size, 0);
668 	ractl->_index = ra->start;
669 	page_cache_ra_order(ractl, ra, order);
672 void page_cache_sync_ra(struct readahead_control *ractl,
675 	bool do_forced_ra = ractl->file && (ractl->file->f_mode & FMODE_RANDOM);
683 	if (!ractl->ra->ra_pages || blk_cgroup_congested()) {
684 		if (!ractl->file)
692 		force_page_cache_ra(ractl, req_count);
696 	ondemand_readahead(ractl, NULL, req_count);
700 void page_cache_async_ra(struct readahead_control *ractl,
704 	if (!ractl->ra->ra_pages)
718 	ondemand_readahead(ractl, folio, req_count);
763  * @ractl: The request to be expanded
776  * The caller must check for this by examining the revised @ractl object for a
779 void readahead_expand(struct readahead_control *ractl,
782 	struct address_space *mapping = ractl->mapping;
783 	struct file_ra_state *ra = ractl->ra;
790 	while (ractl->_index > new_index) {
791 		unsigned long index = ractl->_index - 1;
805 				!ractl->_workingset) {
806 			ractl->_workingset = true;
807 			psi_memstall_enter(&ractl->_pflags);
809 		ractl->_nr_pages++;
810 		ractl->_index = folio->index;
813 	new_len += new_start - readahead_pos(ractl);
817 	while (ractl->_nr_pages < new_nr_pages) {
818 		unsigned long index = ractl->_index + ractl->_nr_pages;
832 				!ractl->_workingset) {
833 			ractl->_workingset = true;
834 			psi_memstall_enter(&ractl->_pflags);
836 		ractl->_nr_pages++;