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