1 // SPDX-License-Identifier: GPL-2.0
30 #include <linux/backing-dev.h>
37  * The mpage code never puts partial pages into a BIO (except for end-of-file).
38  * If a page does not map to a contiguous run of blocks then it simply falls
49 	int err = blk_status_to_errno(bio->bi_status);  in mpage_read_end_io()
60 	int err = blk_status_to_errno(bio->bi_status);  in mpage_write_end_io()
64 			mapping_set_error(fi.folio->mapping, err);  in mpage_write_end_io()
73 	bio->bi_end_io = mpage_read_end_io;  in mpage_bio_submit_read()
81 	bio->bi_end_io = mpage_write_end_io;  in mpage_bio_submit_write()
100 	struct inode *inode = folio->mapping->host;  in map_buffer_to_folio()
110 		if (inode->i_blkbits == PAGE_SHIFT &&  in map_buffer_to_folio()
121 			page_bh->b_state = bh->b_state;  in map_buffer_to_folio()
122 			page_bh->b_bdev = bh->b_bdev;  in map_buffer_to_folio()
123 			page_bh->b_blocknr = bh->b_blocknr;  in map_buffer_to_folio()
126 		page_bh = page_bh->b_this_page;  in map_buffer_to_folio()
145  * blocks are not contiguous on the disk.
153 	struct folio *folio = args->folio;  in do_mpage_readpage()
154 	struct inode *inode = folio->mapping->host;  in do_mpage_readpage()
155 	const unsigned blkbits = inode->i_blkbits;  in do_mpage_readpage()
158 	struct buffer_head *map_bh = &args->map_bh;  in do_mpage_readpage()
171 	gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);  in do_mpage_readpage()
176 	if (args->is_readahead) {  in do_mpage_readpage()
184 	block_in_file = (sector_t)folio->index << (PAGE_SHIFT - blkbits);  in do_mpage_readpage()
185 	last_block = block_in_file + args->nr_pages * blocks_per_page;  in do_mpage_readpage()
186 	last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;  in do_mpage_readpage()
194 	nblocks = map_bh->b_size >> blkbits;  in do_mpage_readpage()
196 			block_in_file > args->first_logical_block &&  in do_mpage_readpage()
197 			block_in_file < (args->first_logical_block + nblocks)) {  in do_mpage_readpage()
198 		unsigned map_offset = block_in_file - args->first_logical_block;  in do_mpage_readpage()
199 		unsigned last = nblocks - map_offset;  in do_mpage_readpage()
201 		first_block = map_bh->b_blocknr + map_offset;  in do_mpage_readpage()
212 		bdev = map_bh->b_bdev;  in do_mpage_readpage()
218 	map_bh->b_folio = folio;  in do_mpage_readpage()
220 		map_bh->b_state = 0;  in do_mpage_readpage()
221 		map_bh->b_size = 0;  in do_mpage_readpage()
224 			map_bh->b_size = (last_block-block_in_file) << blkbits;  in do_mpage_readpage()
225 			if (args->get_block(inode, block_in_file, map_bh, 0))  in do_mpage_readpage()
227 			args->first_logical_block = block_in_file;  in do_mpage_readpage()
251 			goto confused;		/* hole -> non-hole */  in do_mpage_readpage()
253 		/* Contiguous blocks? */  in do_mpage_readpage()
255 			first_block = map_bh->b_blocknr;  in do_mpage_readpage()
256 		else if (first_block + page_block != map_bh->b_blocknr)  in do_mpage_readpage()
258 		nblocks = map_bh->b_size >> blkbits;  in do_mpage_readpage()
268 		bdev = map_bh->b_bdev;  in do_mpage_readpage()
285 	if (args->bio && (args->last_block_in_bio != first_block - 1))  in do_mpage_readpage()
286 		args->bio = mpage_bio_submit_read(args->bio);  in do_mpage_readpage()
289 	if (args->bio == NULL) {  in do_mpage_readpage()
290 		args->bio = bio_alloc(bdev, bio_max_segs(args->nr_pages), opf,  in do_mpage_readpage()
292 		if (args->bio == NULL)  in do_mpage_readpage()
294 		args->bio->bi_iter.bi_sector = first_block << (blkbits - 9);  in do_mpage_readpage()
298 	if (!bio_add_folio(args->bio, folio, length, 0)) {  in do_mpage_readpage()
299 		args->bio = mpage_bio_submit_read(args->bio);  in do_mpage_readpage()
303 	relative_block = block_in_file - args->first_logical_block;  in do_mpage_readpage()
304 	nblocks = map_bh->b_size >> blkbits;  in do_mpage_readpage()
307 		args->bio = mpage_bio_submit_read(args->bio);  in do_mpage_readpage()
309 		args->last_block_in_bio = first_block + blocks_per_page - 1;  in do_mpage_readpage()
311 	return args->bio;  in do_mpage_readpage()
314 	if (args->bio)  in do_mpage_readpage()
315 		args->bio = mpage_bio_submit_read(args->bio);  in do_mpage_readpage()
317 		block_read_full_folio(folio, args->get_block);  in do_mpage_readpage()
324  * mpage_readahead - start reads against pages
333  * - encountering a page which has buffers
334  * - encountering a page which has a non-hole after a hole
335  * - encountering a page with non-contiguous blocks
337  * then this code just gives up and calls the buffer_head-based read function.
338  * It does handle a page which has holes at the end - that is a common case:
339  * the end-of-file on blocksize < PAGE_SIZE setups.
371 		prefetchw(&folio->flags);  in mpage_readahead()
403  * mapping.  We only support pages which are fully mapped-and-dirty, with a
404  * special case for pages which are unmapped at the end: end-of-file.
408  * If all blocks are found to be contiguous then the page can go into the
412  * written, so it can intelligently allocate a suitably-sized BIO.  For now,
413  * just allocate full-size (16-page) BIOs.
439 		bh = bh->b_this_page;  in clean_buffers()
455 	struct bio *bio = mpd->bio;  in __mpage_writepage()
456 	struct address_space *mapping = folio->mapping;  in __mpage_writepage()
457 	struct inode *inode = mapping->host;  in __mpage_writepage()
458 	const unsigned blkbits = inode->i_blkbits;  in __mpage_writepage()
485 				 * block_dirty_folio -> mmapped data  in __mpage_writepage()
495 				goto confused;	/* hole -> non-hole */  in __mpage_writepage()
500 				if (bh->b_blocknr != first_block + page_block)  in __mpage_writepage()
503 				first_block = bh->b_blocknr;  in __mpage_writepage()
508 				boundary_block = bh->b_blocknr;  in __mpage_writepage()
509 				boundary_bdev = bh->b_bdev;  in __mpage_writepage()
511 			bdev = bh->b_bdev;  in __mpage_writepage()
512 		} while ((bh = bh->b_this_page) != head);  in __mpage_writepage()
530 	block_in_file = (sector_t)folio->index << (PAGE_SHIFT - blkbits);  in __mpage_writepage()
535 	if (block_in_file >= (i_size + (1 << blkbits) - 1) >> blkbits)  in __mpage_writepage()
537 	last_block = (i_size - 1) >> blkbits;  in __mpage_writepage()
543 		if (mpd->get_block(inode, block_in_file, &map_bh, 1))  in __mpage_writepage()
584 		length = i_size - folio_pos(folio);  in __mpage_writepage()
591 	if (bio && mpd->last_block_in_bio != first_block - 1)  in __mpage_writepage()
599 		bio->bi_iter.bi_sector = first_block << (blkbits - 9);  in __mpage_writepage()
601 		bio->bi_write_hint = inode->i_write_hint;  in __mpage_writepage()
609 	wbc_account_cgroup_owner(wbc, &folio->page, folio_size(folio));  in __mpage_writepage()
628 		mpd->last_block_in_bio = first_block + blocks_per_page - 1;  in __mpage_writepage()
639 	ret = block_write_full_folio(folio, wbc, mpd->get_block);  in __mpage_writepage()
642 	mpd->bio = bio;  in __mpage_writepage()
647 …* mpage_writepages - walk the list of dirty pages of the given address space & writepage() all of …
649  * @wbc: subtract the number of written pages from *@wbc->nr_to_write