blob: bb9aebe93862d8c03a94990d4b28fc4832e93a1f [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * fs/mpage.c
3 *
4 * Copyright (C) 2002, Linus Torvalds.
5 *
6 * Contains functions related to preparing and submitting BIOs which contain
7 * multiple pagecache pages.
8 *
9 * 15May2002 akpm@zip.com.au
10 * Initial version
11 * 27Jun2002 axboe@suse.de
12 * use bio_add_page() to build bio's just the right size
13 */
14
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/mm.h>
18#include <linux/kdev_t.h>
19#include <linux/bio.h>
20#include <linux/fs.h>
21#include <linux/buffer_head.h>
22#include <linux/blkdev.h>
23#include <linux/highmem.h>
24#include <linux/prefetch.h>
25#include <linux/mpage.h>
26#include <linux/writeback.h>
27#include <linux/backing-dev.h>
28#include <linux/pagevec.h>
29
30/*
31 * I/O completion handler for multipage BIOs.
32 *
33 * The mpage code never puts partial pages into a BIO (except for end-of-file).
34 * If a page does not map to a contiguous run of blocks then it simply falls
35 * back to block_read_full_page().
36 *
37 * Why is this? If a page's completion depends on a number of different BIOs
38 * which can complete in any order (or at the same time) then determining the
39 * status of that page is hard. See end_buffer_async_read() for the details.
40 * There is no point in duplicating all that complexity.
41 */
42static int mpage_end_io_read(struct bio *bio, unsigned int bytes_done, int err)
43{
44 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
45 struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
46
47 if (bio->bi_size)
48 return 1;
49
50 do {
51 struct page *page = bvec->bv_page;
52
53 if (--bvec >= bio->bi_io_vec)
54 prefetchw(&bvec->bv_page->flags);
55
56 if (uptodate) {
57 SetPageUptodate(page);
58 } else {
59 ClearPageUptodate(page);
60 SetPageError(page);
61 }
62 unlock_page(page);
63 } while (bvec >= bio->bi_io_vec);
64 bio_put(bio);
65 return 0;
66}
67
68static int mpage_end_io_write(struct bio *bio, unsigned int bytes_done, int err)
69{
70 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
71 struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
72
73 if (bio->bi_size)
74 return 1;
75
76 do {
77 struct page *page = bvec->bv_page;
78
79 if (--bvec >= bio->bi_io_vec)
80 prefetchw(&bvec->bv_page->flags);
81
Qu Fuping854715b2005-06-04 15:43:29 -070082 if (!uptodate){
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 SetPageError(page);
Qu Fuping854715b2005-06-04 15:43:29 -070084 if (page->mapping)
85 set_bit(AS_EIO, &page->mapping->flags);
86 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 end_page_writeback(page);
88 } while (bvec >= bio->bi_io_vec);
89 bio_put(bio);
90 return 0;
91}
92
Adrian Bunk75c96f82005-05-05 16:16:09 -070093static struct bio *mpage_bio_submit(int rw, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -070094{
95 bio->bi_end_io = mpage_end_io_read;
96 if (rw == WRITE)
97 bio->bi_end_io = mpage_end_io_write;
98 submit_bio(rw, bio);
99 return NULL;
100}
101
102static struct bio *
103mpage_alloc(struct block_device *bdev,
104 sector_t first_sector, int nr_vecs,
105 unsigned int __nocast gfp_flags)
106{
107 struct bio *bio;
108
109 bio = bio_alloc(gfp_flags, nr_vecs);
110
111 if (bio == NULL && (current->flags & PF_MEMALLOC)) {
112 while (!bio && (nr_vecs /= 2))
113 bio = bio_alloc(gfp_flags, nr_vecs);
114 }
115
116 if (bio) {
117 bio->bi_bdev = bdev;
118 bio->bi_sector = first_sector;
119 }
120 return bio;
121}
122
123/*
124 * support function for mpage_readpages. The fs supplied get_block might
125 * return an up to date buffer. This is used to map that buffer into
126 * the page, which allows readpage to avoid triggering a duplicate call
127 * to get_block.
128 *
129 * The idea is to avoid adding buffers to pages that don't already have
130 * them. So when the buffer is up to date and the page size == block size,
131 * this marks the page up to date instead of adding new buffers.
132 */
133static void
134map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
135{
136 struct inode *inode = page->mapping->host;
137 struct buffer_head *page_bh, *head;
138 int block = 0;
139
140 if (!page_has_buffers(page)) {
141 /*
142 * don't make any buffers if there is only one buffer on
143 * the page and the page just needs to be set up to date
144 */
145 if (inode->i_blkbits == PAGE_CACHE_SHIFT &&
146 buffer_uptodate(bh)) {
147 SetPageUptodate(page);
148 return;
149 }
150 create_empty_buffers(page, 1 << inode->i_blkbits, 0);
151 }
152 head = page_buffers(page);
153 page_bh = head;
154 do {
155 if (block == page_block) {
156 page_bh->b_state = bh->b_state;
157 page_bh->b_bdev = bh->b_bdev;
158 page_bh->b_blocknr = bh->b_blocknr;
159 break;
160 }
161 page_bh = page_bh->b_this_page;
162 block++;
163 } while (page_bh != head);
164}
165
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166static struct bio *
167do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
168 sector_t *last_block_in_bio, get_block_t get_block)
169{
170 struct inode *inode = page->mapping->host;
171 const unsigned blkbits = inode->i_blkbits;
172 const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits;
173 const unsigned blocksize = 1 << blkbits;
174 sector_t block_in_file;
175 sector_t last_block;
176 sector_t blocks[MAX_BUF_PER_PAGE];
177 unsigned page_block;
178 unsigned first_hole = blocks_per_page;
179 struct block_device *bdev = NULL;
180 struct buffer_head bh;
181 int length;
182 int fully_mapped = 1;
183
184 if (page_has_buffers(page))
185 goto confused;
186
187 block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits);
188 last_block = (i_size_read(inode) + blocksize - 1) >> blkbits;
189
190 bh.b_page = page;
191 for (page_block = 0; page_block < blocks_per_page;
192 page_block++, block_in_file++) {
193 bh.b_state = 0;
194 if (block_in_file < last_block) {
195 if (get_block(inode, block_in_file, &bh, 0))
196 goto confused;
197 }
198
199 if (!buffer_mapped(&bh)) {
200 fully_mapped = 0;
201 if (first_hole == blocks_per_page)
202 first_hole = page_block;
203 continue;
204 }
205
206 /* some filesystems will copy data into the page during
207 * the get_block call, in which case we don't want to
208 * read it again. map_buffer_to_page copies the data
209 * we just collected from get_block into the page's buffers
210 * so readpage doesn't have to repeat the get_block call
211 */
212 if (buffer_uptodate(&bh)) {
213 map_buffer_to_page(page, &bh, page_block);
214 goto confused;
215 }
216
217 if (first_hole != blocks_per_page)
218 goto confused; /* hole -> non-hole */
219
220 /* Contiguous blocks? */
221 if (page_block && blocks[page_block-1] != bh.b_blocknr-1)
222 goto confused;
223 blocks[page_block] = bh.b_blocknr;
224 bdev = bh.b_bdev;
225 }
226
227 if (first_hole != blocks_per_page) {
228 char *kaddr = kmap_atomic(page, KM_USER0);
229 memset(kaddr + (first_hole << blkbits), 0,
230 PAGE_CACHE_SIZE - (first_hole << blkbits));
231 flush_dcache_page(page);
232 kunmap_atomic(kaddr, KM_USER0);
233 if (first_hole == 0) {
234 SetPageUptodate(page);
235 unlock_page(page);
236 goto out;
237 }
238 } else if (fully_mapped) {
239 SetPageMappedToDisk(page);
240 }
241
242 /*
243 * This page will go to BIO. Do we need to send this BIO off first?
244 */
245 if (bio && (*last_block_in_bio != blocks[0] - 1))
246 bio = mpage_bio_submit(READ, bio);
247
248alloc_new:
249 if (bio == NULL) {
250 bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
251 min_t(int, nr_pages, bio_get_nr_vecs(bdev)),
252 GFP_KERNEL);
253 if (bio == NULL)
254 goto confused;
255 }
256
257 length = first_hole << blkbits;
258 if (bio_add_page(bio, page, length, 0) < length) {
259 bio = mpage_bio_submit(READ, bio);
260 goto alloc_new;
261 }
262
263 if (buffer_boundary(&bh) || (first_hole != blocks_per_page))
264 bio = mpage_bio_submit(READ, bio);
265 else
266 *last_block_in_bio = blocks[blocks_per_page - 1];
267out:
268 return bio;
269
270confused:
271 if (bio)
272 bio = mpage_bio_submit(READ, bio);
273 if (!PageUptodate(page))
274 block_read_full_page(page, get_block);
275 else
276 unlock_page(page);
277 goto out;
278}
279
Martin Waitz67be2dd2005-05-01 08:59:26 -0700280/**
281 * mpage_readpages - populate an address space with some pages, and
282 * start reads against them.
283 *
284 * @mapping: the address_space
285 * @pages: The address of a list_head which contains the target pages. These
286 * pages have their ->index populated and are otherwise uninitialised.
287 *
288 * The page at @pages->prev has the lowest file offset, and reads should be
289 * issued in @pages->prev to @pages->next order.
290 *
291 * @nr_pages: The number of pages at *@pages
292 * @get_block: The filesystem's block mapper function.
293 *
294 * This function walks the pages and the blocks within each page, building and
295 * emitting large BIOs.
296 *
297 * If anything unusual happens, such as:
298 *
299 * - encountering a page which has buffers
300 * - encountering a page which has a non-hole after a hole
301 * - encountering a page with non-contiguous blocks
302 *
303 * then this code just gives up and calls the buffer_head-based read function.
304 * It does handle a page which has holes at the end - that is a common case:
305 * the end-of-file on blocksize < PAGE_CACHE_SIZE setups.
306 *
307 * BH_Boundary explanation:
308 *
309 * There is a problem. The mpage read code assembles several pages, gets all
310 * their disk mappings, and then submits them all. That's fine, but obtaining
311 * the disk mappings may require I/O. Reads of indirect blocks, for example.
312 *
313 * So an mpage read of the first 16 blocks of an ext2 file will cause I/O to be
314 * submitted in the following order:
315 * 12 0 1 2 3 4 5 6 7 8 9 10 11 13 14 15 16
316 * because the indirect block has to be read to get the mappings of blocks
317 * 13,14,15,16. Obviously, this impacts performance.
318 *
319 * So what we do it to allow the filesystem's get_block() function to set
320 * BH_Boundary when it maps block 11. BH_Boundary says: mapping of the block
321 * after this one will require I/O against a block which is probably close to
322 * this one. So you should push what I/O you have currently accumulated.
323 *
324 * This all causes the disk requests to be issued in the correct order.
325 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326int
327mpage_readpages(struct address_space *mapping, struct list_head *pages,
328 unsigned nr_pages, get_block_t get_block)
329{
330 struct bio *bio = NULL;
331 unsigned page_idx;
332 sector_t last_block_in_bio = 0;
333 struct pagevec lru_pvec;
334
335 pagevec_init(&lru_pvec, 0);
336 for (page_idx = 0; page_idx < nr_pages; page_idx++) {
337 struct page *page = list_entry(pages->prev, struct page, lru);
338
339 prefetchw(&page->flags);
340 list_del(&page->lru);
341 if (!add_to_page_cache(page, mapping,
342 page->index, GFP_KERNEL)) {
343 bio = do_mpage_readpage(bio, page,
344 nr_pages - page_idx,
345 &last_block_in_bio, get_block);
346 if (!pagevec_add(&lru_pvec, page))
347 __pagevec_lru_add(&lru_pvec);
348 } else {
349 page_cache_release(page);
350 }
351 }
352 pagevec_lru_add(&lru_pvec);
353 BUG_ON(!list_empty(pages));
354 if (bio)
355 mpage_bio_submit(READ, bio);
356 return 0;
357}
358EXPORT_SYMBOL(mpage_readpages);
359
360/*
361 * This isn't called much at all
362 */
363int mpage_readpage(struct page *page, get_block_t get_block)
364{
365 struct bio *bio = NULL;
366 sector_t last_block_in_bio = 0;
367
368 bio = do_mpage_readpage(bio, page, 1,
369 &last_block_in_bio, get_block);
370 if (bio)
371 mpage_bio_submit(READ, bio);
372 return 0;
373}
374EXPORT_SYMBOL(mpage_readpage);
375
376/*
377 * Writing is not so simple.
378 *
379 * If the page has buffers then they will be used for obtaining the disk
380 * mapping. We only support pages which are fully mapped-and-dirty, with a
381 * special case for pages which are unmapped at the end: end-of-file.
382 *
383 * If the page has no buffers (preferred) then the page is mapped here.
384 *
385 * If all blocks are found to be contiguous then the page can go into the
386 * BIO. Otherwise fall back to the mapping's writepage().
387 *
388 * FIXME: This code wants an estimate of how many pages are still to be
389 * written, so it can intelligently allocate a suitably-sized BIO. For now,
390 * just allocate full-size (16-page) BIOs.
391 */
392static struct bio *
393__mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
394 sector_t *last_block_in_bio, int *ret, struct writeback_control *wbc,
395 writepage_t writepage_fn)
396{
397 struct address_space *mapping = page->mapping;
398 struct inode *inode = page->mapping->host;
399 const unsigned blkbits = inode->i_blkbits;
400 unsigned long end_index;
401 const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits;
402 sector_t last_block;
403 sector_t block_in_file;
404 sector_t blocks[MAX_BUF_PER_PAGE];
405 unsigned page_block;
406 unsigned first_unmapped = blocks_per_page;
407 struct block_device *bdev = NULL;
408 int boundary = 0;
409 sector_t boundary_block = 0;
410 struct block_device *boundary_bdev = NULL;
411 int length;
412 struct buffer_head map_bh;
413 loff_t i_size = i_size_read(inode);
414
415 if (page_has_buffers(page)) {
416 struct buffer_head *head = page_buffers(page);
417 struct buffer_head *bh = head;
418
419 /* If they're all mapped and dirty, do it */
420 page_block = 0;
421 do {
422 BUG_ON(buffer_locked(bh));
423 if (!buffer_mapped(bh)) {
424 /*
425 * unmapped dirty buffers are created by
426 * __set_page_dirty_buffers -> mmapped data
427 */
428 if (buffer_dirty(bh))
429 goto confused;
430 if (first_unmapped == blocks_per_page)
431 first_unmapped = page_block;
432 continue;
433 }
434
435 if (first_unmapped != blocks_per_page)
436 goto confused; /* hole -> non-hole */
437
438 if (!buffer_dirty(bh) || !buffer_uptodate(bh))
439 goto confused;
440 if (page_block) {
441 if (bh->b_blocknr != blocks[page_block-1] + 1)
442 goto confused;
443 }
444 blocks[page_block++] = bh->b_blocknr;
445 boundary = buffer_boundary(bh);
446 if (boundary) {
447 boundary_block = bh->b_blocknr;
448 boundary_bdev = bh->b_bdev;
449 }
450 bdev = bh->b_bdev;
451 } while ((bh = bh->b_this_page) != head);
452
453 if (first_unmapped)
454 goto page_is_mapped;
455
456 /*
457 * Page has buffers, but they are all unmapped. The page was
458 * created by pagein or read over a hole which was handled by
459 * block_read_full_page(). If this address_space is also
460 * using mpage_readpages then this can rarely happen.
461 */
462 goto confused;
463 }
464
465 /*
466 * The page has no buffers: map it to disk
467 */
468 BUG_ON(!PageUptodate(page));
469 block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits);
470 last_block = (i_size - 1) >> blkbits;
471 map_bh.b_page = page;
472 for (page_block = 0; page_block < blocks_per_page; ) {
473
474 map_bh.b_state = 0;
475 if (get_block(inode, block_in_file, &map_bh, 1))
476 goto confused;
477 if (buffer_new(&map_bh))
478 unmap_underlying_metadata(map_bh.b_bdev,
479 map_bh.b_blocknr);
480 if (buffer_boundary(&map_bh)) {
481 boundary_block = map_bh.b_blocknr;
482 boundary_bdev = map_bh.b_bdev;
483 }
484 if (page_block) {
485 if (map_bh.b_blocknr != blocks[page_block-1] + 1)
486 goto confused;
487 }
488 blocks[page_block++] = map_bh.b_blocknr;
489 boundary = buffer_boundary(&map_bh);
490 bdev = map_bh.b_bdev;
491 if (block_in_file == last_block)
492 break;
493 block_in_file++;
494 }
495 BUG_ON(page_block == 0);
496
497 first_unmapped = page_block;
498
499page_is_mapped:
500 end_index = i_size >> PAGE_CACHE_SHIFT;
501 if (page->index >= end_index) {
502 /*
503 * The page straddles i_size. It must be zeroed out on each
504 * and every writepage invokation because it may be mmapped.
505 * "A file is mapped in multiples of the page size. For a file
506 * that is not a multiple of the page size, the remaining memory
507 * is zeroed when mapped, and writes to that region are not
508 * written out to the file."
509 */
510 unsigned offset = i_size & (PAGE_CACHE_SIZE - 1);
511 char *kaddr;
512
513 if (page->index > end_index || !offset)
514 goto confused;
515 kaddr = kmap_atomic(page, KM_USER0);
516 memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
517 flush_dcache_page(page);
518 kunmap_atomic(kaddr, KM_USER0);
519 }
520
521 /*
522 * This page will go to BIO. Do we need to send this BIO off first?
523 */
524 if (bio && *last_block_in_bio != blocks[0] - 1)
525 bio = mpage_bio_submit(WRITE, bio);
526
527alloc_new:
528 if (bio == NULL) {
529 bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
530 bio_get_nr_vecs(bdev), GFP_NOFS|__GFP_HIGH);
531 if (bio == NULL)
532 goto confused;
533 }
534
535 /*
536 * Must try to add the page before marking the buffer clean or
537 * the confused fail path above (OOM) will be very confused when
538 * it finds all bh marked clean (i.e. it will not write anything)
539 */
540 length = first_unmapped << blkbits;
541 if (bio_add_page(bio, page, length, 0) < length) {
542 bio = mpage_bio_submit(WRITE, bio);
543 goto alloc_new;
544 }
545
546 /*
547 * OK, we have our BIO, so we can now mark the buffers clean. Make
548 * sure to only clean buffers which we know we'll be writing.
549 */
550 if (page_has_buffers(page)) {
551 struct buffer_head *head = page_buffers(page);
552 struct buffer_head *bh = head;
553 unsigned buffer_counter = 0;
554
555 do {
556 if (buffer_counter++ == first_unmapped)
557 break;
558 clear_buffer_dirty(bh);
559 bh = bh->b_this_page;
560 } while (bh != head);
561
562 /*
563 * we cannot drop the bh if the page is not uptodate
564 * or a concurrent readpage would fail to serialize with the bh
565 * and it would read from disk before we reach the platter.
566 */
567 if (buffer_heads_over_limit && PageUptodate(page))
568 try_to_free_buffers(page);
569 }
570
571 BUG_ON(PageWriteback(page));
572 set_page_writeback(page);
573 unlock_page(page);
574 if (boundary || (first_unmapped != blocks_per_page)) {
575 bio = mpage_bio_submit(WRITE, bio);
576 if (boundary_block) {
577 write_boundary_block(boundary_bdev,
578 boundary_block, 1 << blkbits);
579 }
580 } else {
581 *last_block_in_bio = blocks[blocks_per_page - 1];
582 }
583 goto out;
584
585confused:
586 if (bio)
587 bio = mpage_bio_submit(WRITE, bio);
588
589 if (writepage_fn) {
590 *ret = (*writepage_fn)(page, wbc);
591 } else {
592 *ret = -EAGAIN;
593 goto out;
594 }
595 /*
596 * The caller has a ref on the inode, so *mapping is stable
597 */
598 if (*ret) {
599 if (*ret == -ENOSPC)
600 set_bit(AS_ENOSPC, &mapping->flags);
601 else
602 set_bit(AS_EIO, &mapping->flags);
603 }
604out:
605 return bio;
606}
607
608/**
609 * mpage_writepages - walk the list of dirty pages of the given
610 * address space and writepage() all of them.
611 *
612 * @mapping: address space structure to write
613 * @wbc: subtract the number of written pages from *@wbc->nr_to_write
614 * @get_block: the filesystem's block mapper function.
615 * If this is NULL then use a_ops->writepage. Otherwise, go
616 * direct-to-BIO.
617 *
618 * This is a library function, which implements the writepages()
619 * address_space_operation.
620 *
621 * If a page is already under I/O, generic_writepages() skips it, even
622 * if it's dirty. This is desirable behaviour for memory-cleaning writeback,
623 * but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
624 * and msync() need to guarantee that all the data which was dirty at the time
625 * the call was made get new I/O started against them. If wbc->sync_mode is
626 * WB_SYNC_ALL then we were called for data integrity and we must wait for
627 * existing IO to complete.
628 */
629int
630mpage_writepages(struct address_space *mapping,
631 struct writeback_control *wbc, get_block_t get_block)
632{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 struct backing_dev_info *bdi = mapping->backing_dev_info;
634 struct bio *bio = NULL;
635 sector_t last_block_in_bio = 0;
636 int ret = 0;
637 int done = 0;
638 int (*writepage)(struct page *page, struct writeback_control *wbc);
639 struct pagevec pvec;
640 int nr_pages;
641 pgoff_t index;
642 pgoff_t end = -1; /* Inclusive */
643 int scanned = 0;
644 int is_range = 0;
645
646 if (wbc->nonblocking && bdi_write_congested(bdi)) {
647 wbc->encountered_congestion = 1;
648 return 0;
649 }
650
651 writepage = NULL;
652 if (get_block == NULL)
653 writepage = mapping->a_ops->writepage;
654
655 pagevec_init(&pvec, 0);
656 if (wbc->sync_mode == WB_SYNC_NONE) {
657 index = mapping->writeback_index; /* Start from prev offset */
658 } else {
659 index = 0; /* whole-file sweep */
660 scanned = 1;
661 }
662 if (wbc->start || wbc->end) {
663 index = wbc->start >> PAGE_CACHE_SHIFT;
664 end = wbc->end >> PAGE_CACHE_SHIFT;
665 is_range = 1;
666 scanned = 1;
667 }
668retry:
669 while (!done && (index <= end) &&
670 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
671 PAGECACHE_TAG_DIRTY,
672 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
673 unsigned i;
674
675 scanned = 1;
676 for (i = 0; i < nr_pages; i++) {
677 struct page *page = pvec.pages[i];
678
679 /*
680 * At this point we hold neither mapping->tree_lock nor
681 * lock on the page itself: the page may be truncated or
682 * invalidated (changing page->mapping to NULL), or even
683 * swizzled back from swapper_space to tmpfs file
684 * mapping
685 */
686
687 lock_page(page);
688
689 if (unlikely(page->mapping != mapping)) {
690 unlock_page(page);
691 continue;
692 }
693
694 if (unlikely(is_range) && page->index > end) {
695 done = 1;
696 unlock_page(page);
697 continue;
698 }
699
700 if (wbc->sync_mode != WB_SYNC_NONE)
701 wait_on_page_writeback(page);
702
703 if (PageWriteback(page) ||
704 !clear_page_dirty_for_io(page)) {
705 unlock_page(page);
706 continue;
707 }
708
709 if (writepage) {
710 ret = (*writepage)(page, wbc);
711 if (ret) {
712 if (ret == -ENOSPC)
713 set_bit(AS_ENOSPC,
714 &mapping->flags);
715 else
716 set_bit(AS_EIO,
717 &mapping->flags);
718 }
719 } else {
720 bio = __mpage_writepage(bio, page, get_block,
721 &last_block_in_bio, &ret, wbc,
Andrew Mortond17d7fa2005-05-05 16:16:02 -0700722 page->mapping->a_ops->writepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 }
Nikita Danilov552fca42005-05-01 08:58:39 -0700724 if (unlikely(ret == WRITEPAGE_ACTIVATE))
725 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726 if (ret || (--(wbc->nr_to_write) <= 0))
727 done = 1;
728 if (wbc->nonblocking && bdi_write_congested(bdi)) {
729 wbc->encountered_congestion = 1;
730 done = 1;
731 }
732 }
733 pagevec_release(&pvec);
734 cond_resched();
735 }
736 if (!scanned && !done) {
737 /*
738 * We hit the last page and there is more work to be done: wrap
739 * back to the start of the file
740 */
741 scanned = 1;
742 index = 0;
743 goto retry;
744 }
745 if (!is_range)
746 mapping->writeback_index = index;
747 if (bio)
748 mpage_bio_submit(WRITE, bio);
749 return ret;
750}
751EXPORT_SYMBOL(mpage_writepages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752
753int mpage_writepage(struct page *page, get_block_t get_block,
754 struct writeback_control *wbc)
755{
756 int ret = 0;
757 struct bio *bio;
758 sector_t last_block_in_bio = 0;
759
760 bio = __mpage_writepage(NULL, page, get_block,
761 &last_block_in_bio, &ret, wbc, NULL);
762 if (bio)
763 mpage_bio_submit(WRITE, bio);
764
765 return ret;
766}
767EXPORT_SYMBOL(mpage_writepage);