1// SPDX-License-Identifier: GPL-2.0
2/*
3 * fs/mpage.c
4 *
5 * Copyright (C) 2002, Linus Torvalds.
6 *
7 * Contains functions related to preparing and submitting BIOs which contain
8 * multiple pagecache pages.
9 *
10 * 15May2002 Andrew Morton
11 * Initial version
12 * 27Jun2002 axboe@suse.de
13 * use bio_add_page() to build bio's just the right size
14 */
15
16#include <linux/kernel.h>
17#include <linux/export.h>
18#include <linux/mm.h>
19#include <linux/kdev_t.h>
20#include <linux/gfp.h>
21#include <linux/bio.h>
22#include <linux/fs.h>
23#include <linux/buffer_head.h>
24#include <linux/blkdev.h>
25#include <linux/highmem.h>
26#include <linux/prefetch.h>
27#include <linux/mpage.h>
28#include <linux/mm_inline.h>
29#include <linux/writeback.h>
30#include <linux/backing-dev.h>
31#include <linux/pagevec.h>
32#include <linux/cleancache.h>
33#include "internal.h"
34
35/*
36 * I/O completion handler for multipage BIOs.
37 *
38 * The mpage code never puts partial pages into a BIO (except for end-of-file).
39 * If a page does not map to a contiguous run of blocks then it simply falls
40 * back to block_read_full_page().
41 *
42 * Why is this? If a page's completion depends on a number of different BIOs
43 * which can complete in any order (or at the same time) then determining the
44 * status of that page is hard. See end_buffer_async_read() for the details.
45 * There is no point in duplicating all that complexity.
46 */
47static void mpage_end_io(struct bio *bio)
48{
49 struct bio_vec *bv;
50 int i;
51 struct bvec_iter_all iter_all;
52
53 bio_for_each_segment_all(bv, bio, i, iter_all) {
54 struct page *page = bv->bv_page;
55 page_endio(page, bio_op(bio),
56 blk_status_to_errno(bio->bi_status));
57 }
58
59 bio_put(bio);
60}
61
62static struct bio *mpage_bio_submit(int op, int op_flags, struct bio *bio)
63{
64 bio->bi_end_io = mpage_end_io;
65 bio_set_op_attrs(bio, op, op_flags);
66 guard_bio_eod(op, bio);
67 submit_bio(bio);
68 return NULL;
69}
70
71static struct bio *
72mpage_alloc(struct block_device *bdev,
73 sector_t first_sector, int nr_vecs,
74 gfp_t gfp_flags)
75{
76 struct bio *bio;
77
78 /* Restrict the given (page cache) mask for slab allocations */
79 gfp_flags &= GFP_KERNEL;
80 bio = bio_alloc(gfp_flags, nr_vecs);
81
82 if (bio == NULL && (current->flags & PF_MEMALLOC)) {
83 while (!bio && (nr_vecs /= 2))
84 bio = bio_alloc(gfp_flags, nr_vecs);
85 }
86
87 if (bio) {
88 bio_set_dev(bio, bdev);
89 bio->bi_iter.bi_sector = first_sector;
90 }
91 return bio;
92}
93
94/*
95 * support function for mpage_readpages. The fs supplied get_block might
96 * return an up to date buffer. This is used to map that buffer into
97 * the page, which allows readpage to avoid triggering a duplicate call
98 * to get_block.
99 *
100 * The idea is to avoid adding buffers to pages that don't already have
101 * them. So when the buffer is up to date and the page size == block size,
102 * this marks the page up to date instead of adding new buffers.
103 */
104static void
105map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
106{
107 struct inode *inode = page->mapping->host;
108 struct buffer_head *page_bh, *head;
109 int block = 0;
110
111 if (!page_has_buffers(page)) {
112 /*
113 * don't make any buffers if there is only one buffer on
114 * the page and the page just needs to be set up to date
115 */
116 if (inode->i_blkbits == PAGE_SHIFT &&
117 buffer_uptodate(bh)) {
118 SetPageUptodate(page);
119 return;
120 }
121 create_empty_buffers(page, i_blocksize(inode), 0);
122 }
123 head = page_buffers(page);
124 page_bh = head;
125 do {
126 if (block == page_block) {
127 page_bh->b_state = bh->b_state;
128 page_bh->b_bdev = bh->b_bdev;
129 page_bh->b_blocknr = bh->b_blocknr;
130 break;
131 }
132 page_bh = page_bh->b_this_page;
133 block++;
134 } while (page_bh != head);
135}
136
137struct mpage_readpage_args {
138 struct bio *bio;
139 struct page *page;
140 unsigned int nr_pages;
141 bool is_readahead;
142 sector_t last_block_in_bio;
143 struct buffer_head map_bh;
144 unsigned long first_logical_block;
145 get_block_t *get_block;
146};
147
148/*
149 * This is the worker routine which does all the work of mapping the disk
150 * blocks and constructs largest possible bios, submits them for IO if the
151 * blocks are not contiguous on the disk.
152 *
153 * We pass a buffer_head back and forth and use its buffer_mapped() flag to
154 * represent the validity of its disk mapping and to decide when to do the next
155 * get_block() call.
156 */
157static struct bio *do_mpage_readpage(struct mpage_readpage_args *args)
158{
159 struct page *page = args->page;
160 struct inode *inode = page->mapping->host;
161 const unsigned blkbits = inode->i_blkbits;
162 const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
163 const unsigned blocksize = 1 << blkbits;
164 struct buffer_head *map_bh = &args->map_bh;
165 sector_t block_in_file;
166 sector_t last_block;
167 sector_t last_block_in_file;
168 sector_t blocks[MAX_BUF_PER_PAGE];
169 unsigned page_block;
170 unsigned first_hole = blocks_per_page;
171 struct block_device *bdev = NULL;
172 int length;
173 int fully_mapped = 1;
174 int op_flags;
175 unsigned nblocks;
176 unsigned relative_block;
177 gfp_t gfp;
178
179 if (args->is_readahead) {
180 op_flags = REQ_RAHEAD;
181 gfp = readahead_gfp_mask(page->mapping);
182 } else {
183 op_flags = 0;
184 gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
185 }
186
187 if (page_has_buffers(page))
188 goto confused;
189
190 block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits);
191 last_block = block_in_file + args->nr_pages * blocks_per_page;
192 last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
193 if (last_block > last_block_in_file)
194 last_block = last_block_in_file;
195 page_block = 0;
196
197 /*
198 * Map blocks using the result from the previous get_blocks call first.
199 */
200 nblocks = map_bh->b_size >> blkbits;
201 if (buffer_mapped(map_bh) &&
202 block_in_file > args->first_logical_block &&
203 block_in_file < (args->first_logical_block + nblocks)) {
204 unsigned map_offset = block_in_file - args->first_logical_block;
205 unsigned last = nblocks - map_offset;
206
207 for (relative_block = 0; ; relative_block++) {
208 if (relative_block == last) {
209 clear_buffer_mapped(map_bh);
210 break;
211 }
212 if (page_block == blocks_per_page)
213 break;
214 blocks[page_block] = map_bh->b_blocknr + map_offset +
215 relative_block;
216 page_block++;
217 block_in_file++;
218 }
219 bdev = map_bh->b_bdev;
220 }
221
222 /*
223 * Then do more get_blocks calls until we are done with this page.
224 */
225 map_bh->b_page = page;
226 while (page_block < blocks_per_page) {
227 map_bh->b_state = 0;
228 map_bh->b_size = 0;
229
230 if (block_in_file < last_block) {
231 map_bh->b_size = (last_block-block_in_file) << blkbits;
232 if (args->get_block(inode, block_in_file, map_bh, 0))
233 goto confused;
234 args->first_logical_block = block_in_file;
235 }
236
237 if (!buffer_mapped(map_bh)) {
238 fully_mapped = 0;
239 if (first_hole == blocks_per_page)
240 first_hole = page_block;
241 page_block++;
242 block_in_file++;
243 continue;
244 }
245
246 /* some filesystems will copy data into the page during
247 * the get_block call, in which case we don't want to
248 * read it again. map_buffer_to_page copies the data
249 * we just collected from get_block into the page's buffers
250 * so readpage doesn't have to repeat the get_block call
251 */
252 if (buffer_uptodate(map_bh)) {
253 map_buffer_to_page(page, map_bh, page_block);
254 goto confused;
255 }
256
257 if (first_hole != blocks_per_page)
258 goto confused; /* hole -> non-hole */
259
260 /* Contiguous blocks? */
261 if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1)
262 goto confused;
263 nblocks = map_bh->b_size >> blkbits;
264 for (relative_block = 0; ; relative_block++) {
265 if (relative_block == nblocks) {
266 clear_buffer_mapped(map_bh);
267 break;
268 } else if (page_block == blocks_per_page)
269 break;
270 blocks[page_block] = map_bh->b_blocknr+relative_block;
271 page_block++;
272 block_in_file++;
273 }
274 bdev = map_bh->b_bdev;
275 }
276
277 if (first_hole != blocks_per_page) {
278 zero_user_segment(page, first_hole << blkbits, PAGE_SIZE);
279 if (first_hole == 0) {
280 SetPageUptodate(page);
281 unlock_page(page);
282 goto out;
283 }
284 } else if (fully_mapped) {
285 SetPageMappedToDisk(page);
286 }
287
288 if (fully_mapped && blocks_per_page == 1 && !PageUptodate(page) &&
289 cleancache_get_page(page) == 0) {
290 SetPageUptodate(page);
291 goto confused;
292 }
293
294 /*
295 * This page will go to BIO. Do we need to send this BIO off first?
296 */
297 if (args->bio && (args->last_block_in_bio != blocks[0] - 1))
298 args->bio = mpage_bio_submit(REQ_OP_READ, op_flags, args->bio);
299
300alloc_new:
301 if (args->bio == NULL) {
302 if (first_hole == blocks_per_page) {
303 if (!bdev_read_page(bdev, blocks[0] << (blkbits - 9),
304 page))
305 goto out;
306 }
307 args->bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
308 min_t(int, args->nr_pages,
309 BIO_MAX_PAGES),
310 gfp);
311 if (args->bio == NULL)
312 goto confused;
313 }
314
315 length = first_hole << blkbits;
316 if (bio_add_page(args->bio, page, length, 0) < length) {
317 args->bio = mpage_bio_submit(REQ_OP_READ, op_flags, args->bio);
318 goto alloc_new;
319 }
320
321 relative_block = block_in_file - args->first_logical_block;
322 nblocks = map_bh->b_size >> blkbits;
323 if ((buffer_boundary(map_bh) && relative_block == nblocks) ||
324 (first_hole != blocks_per_page))
325 args->bio = mpage_bio_submit(REQ_OP_READ, op_flags, args->bio);
326 else
327 args->last_block_in_bio = blocks[blocks_per_page - 1];
328out:
329 return args->bio;
330
331confused:
332 if (args->bio)
333 args->bio = mpage_bio_submit(REQ_OP_READ, op_flags, args->bio);
334 if (!PageUptodate(page))
335 block_read_full_page(page, args->get_block);
336 else
337 unlock_page(page);
338 goto out;
339}
340
341/**
342 * mpage_readpages - populate an address space with some pages & start reads against them
343 * @mapping: the address_space
344 * @pages: The address of a list_head which contains the target pages. These
345 * pages have their ->index populated and are otherwise uninitialised.
346 * The page at @pages->prev has the lowest file offset, and reads should be
347 * issued in @pages->prev to @pages->next order.
348 * @nr_pages: The number of pages at *@pages
349 * @get_block: The filesystem's block mapper function.
350 *
351 * This function walks the pages and the blocks within each page, building and
352 * emitting large BIOs.
353 *
354 * If anything unusual happens, such as:
355 *
356 * - encountering a page which has buffers
357 * - encountering a page which has a non-hole after a hole
358 * - encountering a page with non-contiguous blocks
359 *
360 * then this code just gives up and calls the buffer_head-based read function.
361 * It does handle a page which has holes at the end - that is a common case:
362 * the end-of-file on blocksize < PAGE_SIZE setups.
363 *
364 * BH_Boundary explanation:
365 *
366 * There is a problem. The mpage read code assembles several pages, gets all
367 * their disk mappings, and then submits them all. That's fine, but obtaining
368 * the disk mappings may require I/O. Reads of indirect blocks, for example.
369 *
370 * So an mpage read of the first 16 blocks of an ext2 file will cause I/O to be
371 * submitted in the following order:
372 *
373 * 12 0 1 2 3 4 5 6 7 8 9 10 11 13 14 15 16
374 *
375 * because the indirect block has to be read to get the mappings of blocks
376 * 13,14,15,16. Obviously, this impacts performance.
377 *
378 * So what we do it to allow the filesystem's get_block() function to set
379 * BH_Boundary when it maps block 11. BH_Boundary says: mapping of the block
380 * after this one will require I/O against a block which is probably close to
381 * this one. So you should push what I/O you have currently accumulated.
382 *
383 * This all causes the disk requests to be issued in the correct order.
384 */
385int
386mpage_readpages(struct address_space *mapping, struct list_head *pages,
387 unsigned nr_pages, get_block_t get_block)
388{
389 struct mpage_readpage_args args = {
390 .get_block = get_block,
391 .is_readahead = true,
392 };
393 unsigned page_idx;
394
395 for (page_idx = 0; page_idx < nr_pages; page_idx++) {
396 struct page *page = lru_to_page(pages);
397
398 prefetchw(&page->flags);
399 list_del(&page->lru);
400 if (!add_to_page_cache_lru(page, mapping,
401 page->index,
402 readahead_gfp_mask(mapping))) {
403 args.page = page;
404 args.nr_pages = nr_pages - page_idx;
405 args.bio = do_mpage_readpage(&args);
406 }
407 put_page(page);
408 }
409 BUG_ON(!list_empty(pages));
410 if (args.bio)
411 mpage_bio_submit(REQ_OP_READ, REQ_RAHEAD, args.bio);
412 return 0;
413}
414EXPORT_SYMBOL(mpage_readpages);
415
416/*
417 * This isn't called much at all
418 */
419int mpage_readpage(struct page *page, get_block_t get_block)
420{
421 struct mpage_readpage_args args = {
422 .page = page,
423 .nr_pages = 1,
424 .get_block = get_block,
425 };
426
427 args.bio = do_mpage_readpage(&args);
428 if (args.bio)
429 mpage_bio_submit(REQ_OP_READ, 0, args.bio);
430 return 0;
431}
432EXPORT_SYMBOL(mpage_readpage);
433
434/*
435 * Writing is not so simple.
436 *
437 * If the page has buffers then they will be used for obtaining the disk
438 * mapping. We only support pages which are fully mapped-and-dirty, with a
439 * special case for pages which are unmapped at the end: end-of-file.
440 *
441 * If the page has no buffers (preferred) then the page is mapped here.
442 *
443 * If all blocks are found to be contiguous then the page can go into the
444 * BIO. Otherwise fall back to the mapping's writepage().
445 *
446 * FIXME: This code wants an estimate of how many pages are still to be
447 * written, so it can intelligently allocate a suitably-sized BIO. For now,
448 * just allocate full-size (16-page) BIOs.
449 */
450
451struct mpage_data {
452 struct bio *bio;
453 sector_t last_block_in_bio;
454 get_block_t *get_block;
455 unsigned use_writepage;
456};
457
458/*
459 * We have our BIO, so we can now mark the buffers clean. Make
460 * sure to only clean buffers which we know we'll be writing.
461 */
462static void clean_buffers(struct page *page, unsigned first_unmapped)
463{
464 unsigned buffer_counter = 0;
465 struct buffer_head *bh, *head;
466 if (!page_has_buffers(page))
467 return;
468 head = page_buffers(page);
469 bh = head;
470
471 do {
472 if (buffer_counter++ == first_unmapped)
473 break;
474 clear_buffer_dirty(bh);
475 bh = bh->b_this_page;
476 } while (bh != head);
477
478 /*
479 * we cannot drop the bh if the page is not uptodate or a concurrent
480 * readpage would fail to serialize with the bh and it would read from
481 * disk before we reach the platter.
482 */
483 if (buffer_heads_over_limit && PageUptodate(page))
484 try_to_free_buffers(page);
485}
486
487/*
488 * For situations where we want to clean all buffers attached to a page.
489 * We don't need to calculate how many buffers are attached to the page,
490 * we just need to specify a number larger than the maximum number of buffers.
491 */
492void clean_page_buffers(struct page *page)
493{
494 clean_buffers(page, ~0U);
495}
496
497static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
498 void *data)
499{
500 struct mpage_data *mpd = data;
501 struct bio *bio = mpd->bio;
502 struct address_space *mapping = page->mapping;
503 struct inode *inode = page->mapping->host;
504 const unsigned blkbits = inode->i_blkbits;
505 unsigned long end_index;
506 const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
507 sector_t last_block;
508 sector_t block_in_file;
509 sector_t blocks[MAX_BUF_PER_PAGE];
510 unsigned page_block;
511 unsigned first_unmapped = blocks_per_page;
512 struct block_device *bdev = NULL;
513 int boundary = 0;
514 sector_t boundary_block = 0;
515 struct block_device *boundary_bdev = NULL;
516 int length;
517 struct buffer_head map_bh;
518 loff_t i_size = i_size_read(inode);
519 int ret = 0;
520 int op_flags = wbc_to_write_flags(wbc);
521
522 if (page_has_buffers(page)) {
523 struct buffer_head *head = page_buffers(page);
524 struct buffer_head *bh = head;
525
526 /* If they're all mapped and dirty, do it */
527 page_block = 0;
528 do {
529 BUG_ON(buffer_locked(bh));
530 if (!buffer_mapped(bh)) {
531 /*
532 * unmapped dirty buffers are created by
533 * __set_page_dirty_buffers -> mmapped data
534 */
535 if (buffer_dirty(bh))
536 goto confused;
537 if (first_unmapped == blocks_per_page)
538 first_unmapped = page_block;
539 continue;
540 }
541
542 if (first_unmapped != blocks_per_page)
543 goto confused; /* hole -> non-hole */
544
545 if (!buffer_dirty(bh) || !buffer_uptodate(bh))
546 goto confused;
547 if (page_block) {
548 if (bh->b_blocknr != blocks[page_block-1] + 1)
549 goto confused;
550 }
551 blocks[page_block++] = bh->b_blocknr;
552 boundary = buffer_boundary(bh);
553 if (boundary) {
554 boundary_block = bh->b_blocknr;
555 boundary_bdev = bh->b_bdev;
556 }
557 bdev = bh->b_bdev;
558 } while ((bh = bh->b_this_page) != head);
559
560 if (first_unmapped)
561 goto page_is_mapped;
562
563 /*
564 * Page has buffers, but they are all unmapped. The page was
565 * created by pagein or read over a hole which was handled by
566 * block_read_full_page(). If this address_space is also
567 * using mpage_readpages then this can rarely happen.
568 */
569 goto confused;
570 }
571
572 /*
573 * The page has no buffers: map it to disk
574 */
575 BUG_ON(!PageUptodate(page));
576 block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits);
577 last_block = (i_size - 1) >> blkbits;
578 map_bh.b_page = page;
579 for (page_block = 0; page_block < blocks_per_page; ) {
580
581 map_bh.b_state = 0;
582 map_bh.b_size = 1 << blkbits;
583 if (mpd->get_block(inode, block_in_file, &map_bh, 1))
584 goto confused;
585 if (buffer_new(&map_bh))
586 clean_bdev_bh_alias(&map_bh);
587 if (buffer_boundary(&map_bh)) {
588 boundary_block = map_bh.b_blocknr;
589 boundary_bdev = map_bh.b_bdev;
590 }
591 if (page_block) {
592 if (map_bh.b_blocknr != blocks[page_block-1] + 1)
593 goto confused;
594 }
595 blocks[page_block++] = map_bh.b_blocknr;
596 boundary = buffer_boundary(&map_bh);
597 bdev = map_bh.b_bdev;
598 if (block_in_file == last_block)
599 break;
600 block_in_file++;
601 }
602 BUG_ON(page_block == 0);
603
604 first_unmapped = page_block;
605
606page_is_mapped:
607 end_index = i_size >> PAGE_SHIFT;
608 if (page->index >= end_index) {
609 /*
610 * The page straddles i_size. It must be zeroed out on each
611 * and every writepage invocation because it may be mmapped.
612 * "A file is mapped in multiples of the page size. For a file
613 * that is not a multiple of the page size, the remaining memory
614 * is zeroed when mapped, and writes to that region are not
615 * written out to the file."
616 */
617 unsigned offset = i_size & (PAGE_SIZE - 1);
618
619 if (page->index > end_index || !offset)
620 goto confused;
621 zero_user_segment(page, offset, PAGE_SIZE);
622 }
623
624 /*
625 * This page will go to BIO. Do we need to send this BIO off first?
626 */
627 if (bio && mpd->last_block_in_bio != blocks[0] - 1)
628 bio = mpage_bio_submit(REQ_OP_WRITE, op_flags, bio);
629
630alloc_new:
631 if (bio == NULL) {
632 if (first_unmapped == blocks_per_page) {
633 if (!bdev_write_page(bdev, blocks[0] << (blkbits - 9),
634 page, wbc))
635 goto out;
636 }
637 bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
638 BIO_MAX_PAGES, GFP_NOFS|__GFP_HIGH);
639 if (bio == NULL)
640 goto confused;
641
642 wbc_init_bio(wbc, bio);
643 bio->bi_write_hint = inode->i_write_hint;
644 }
645
646 /*
647 * Must try to add the page before marking the buffer clean or
648 * the confused fail path above (OOM) will be very confused when
649 * it finds all bh marked clean (i.e. it will not write anything)
650 */
651 wbc_account_io(wbc, page, PAGE_SIZE);
652 length = first_unmapped << blkbits;
653 if (bio_add_page(bio, page, length, 0) < length) {
654 bio = mpage_bio_submit(REQ_OP_WRITE, op_flags, bio);
655 goto alloc_new;
656 }
657
658 clean_buffers(page, first_unmapped);
659
660 BUG_ON(PageWriteback(page));
661 set_page_writeback(page);
662 unlock_page(page);
663 if (boundary || (first_unmapped != blocks_per_page)) {
664 bio = mpage_bio_submit(REQ_OP_WRITE, op_flags, bio);
665 if (boundary_block) {
666 write_boundary_block(boundary_bdev,
667 boundary_block, 1 << blkbits);
668 }
669 } else {
670 mpd->last_block_in_bio = blocks[blocks_per_page - 1];
671 }
672 goto out;
673
674confused:
675 if (bio)
676 bio = mpage_bio_submit(REQ_OP_WRITE, op_flags, bio);
677
678 if (mpd->use_writepage) {
679 ret = mapping->a_ops->writepage(page, wbc);
680 } else {
681 ret = -EAGAIN;
682 goto out;
683 }
684 /*
685 * The caller has a ref on the inode, so *mapping is stable
686 */
687 mapping_set_error(mapping, ret);
688out:
689 mpd->bio = bio;
690 return ret;
691}
692
693/**
694 * mpage_writepages - walk the list of dirty pages of the given address space & writepage() all of them
695 * @mapping: address space structure to write
696 * @wbc: subtract the number of written pages from *@wbc->nr_to_write
697 * @get_block: the filesystem's block mapper function.
698 * If this is NULL then use a_ops->writepage. Otherwise, go
699 * direct-to-BIO.
700 *
701 * This is a library function, which implements the writepages()
702 * address_space_operation.
703 *
704 * If a page is already under I/O, generic_writepages() skips it, even
705 * if it's dirty. This is desirable behaviour for memory-cleaning writeback,
706 * but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
707 * and msync() need to guarantee that all the data which was dirty at the time
708 * the call was made get new I/O started against them. If wbc->sync_mode is
709 * WB_SYNC_ALL then we were called for data integrity and we must wait for
710 * existing IO to complete.
711 */
712int
713mpage_writepages(struct address_space *mapping,
714 struct writeback_control *wbc, get_block_t get_block)
715{
716 struct blk_plug plug;
717 int ret;
718
719 blk_start_plug(&plug);
720
721 if (!get_block)
722 ret = generic_writepages(mapping, wbc);
723 else {
724 struct mpage_data mpd = {
725 .bio = NULL,
726 .last_block_in_bio = 0,
727 .get_block = get_block,
728 .use_writepage = 1,
729 };
730
731 ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd);
732 if (mpd.bio) {
733 int op_flags = (wbc->sync_mode == WB_SYNC_ALL ?
734 REQ_SYNC : 0);
735 mpage_bio_submit(REQ_OP_WRITE, op_flags, mpd.bio);
736 }
737 }
738 blk_finish_plug(&plug);
739 return ret;
740}
741EXPORT_SYMBOL(mpage_writepages);
742
743int mpage_writepage(struct page *page, get_block_t get_block,
744 struct writeback_control *wbc)
745{
746 struct mpage_data mpd = {
747 .bio = NULL,
748 .last_block_in_bio = 0,
749 .get_block = get_block,
750 .use_writepage = 0,
751 };
752 int ret = __mpage_writepage(page, wbc, &mpd);
753 if (mpd.bio) {
754 int op_flags = (wbc->sync_mode == WB_SYNC_ALL ?
755 REQ_SYNC : 0);
756 mpage_bio_submit(REQ_OP_WRITE, op_flags, mpd.bio);
757 }
758 return ret;
759}
760EXPORT_SYMBOL(mpage_writepage);
761