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1da177e Linux-2.6.12-rc2
Linus Torvalds authored
1 /*
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 *
e1f8e87 Remove Andrew Morton's old email accounts
Francois Cami authored
9 * 15May2002 Andrew Morton
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
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>
5a0e3ad include cleanup: Update gfp.h and slab.h includes to prepare for brea…
Tejun Heo authored
19 #include <linux/gfp.h>
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
20 #include <linux/bio.h>
21 #include <linux/fs.h>
22 #include <linux/buffer_head.h>
23 #include <linux/blkdev.h>
24 #include <linux/highmem.h>
25 #include <linux/prefetch.h>
26 #include <linux/mpage.h>
27 #include <linux/writeback.h>
28 #include <linux/backing-dev.h>
29 #include <linux/pagevec.h>
c515e1f mm/fs: add hooks to support cleancache
Dan Magenheimer authored
30 #include <linux/cleancache.h>
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
31
32 /*
33 * I/O completion handler for multipage BIOs.
34 *
35 * The mpage code never puts partial pages into a BIO (except for end-of-file).
36 * If a page does not map to a contiguous run of blocks then it simply falls
37 * back to block_read_full_page().
38 *
39 * Why is this? If a page's completion depends on a number of different BIOs
40 * which can complete in any order (or at the same time) then determining the
41 * status of that page is hard. See end_buffer_async_read() for the details.
42 * There is no point in duplicating all that complexity.
43 */
c32b0d4 fs/mpage.c: consolidate code
Hai Shan authored
44 static void mpage_end_io(struct bio *bio, int err)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
45 {
46 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
47 struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
48
49 do {
50 struct page *page = bvec->bv_page;
51
52 if (--bvec >= bio->bi_io_vec)
53 prefetchw(&bvec->bv_page->flags);
c32b0d4 fs/mpage.c: consolidate code
Hai Shan authored
54 if (bio_data_dir(bio) == READ) {
55 if (uptodate) {
56 SetPageUptodate(page);
57 } else {
58 ClearPageUptodate(page);
59 SetPageError(page);
60 }
61 unlock_page(page);
62 } else { /* bio_data_dir(bio) == WRITE */
63 if (!uptodate) {
64 SetPageError(page);
65 if (page->mapping)
66 set_bit(AS_EIO, &page->mapping->flags);
67 }
68 end_page_writeback(page);
854715b [PATCH] mpage_end_io_write() I/O error handling fix
Qu Fuping authored
69 }
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
70 } while (bvec >= bio->bi_io_vec);
71 bio_put(bio);
72 }
73
ced117c Remove two unneeded exports and make two symbols static in fs/mpage.c
Dmitri Vorobiev authored
74 static struct bio *mpage_bio_submit(int rw, struct bio *bio)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
75 {
c32b0d4 fs/mpage.c: consolidate code
Hai Shan authored
76 bio->bi_end_io = mpage_end_io;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
77 submit_bio(rw, bio);
78 return NULL;
79 }
80
81 static struct bio *
82 mpage_alloc(struct block_device *bdev,
83 sector_t first_sector, int nr_vecs,
dd0fc66 [PATCH] gfp flags annotations - part 1
Al Viro authored
84 gfp_t gfp_flags)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
85 {
86 struct bio *bio;
87
88 bio = bio_alloc(gfp_flags, nr_vecs);
89
90 if (bio == NULL && (current->flags & PF_MEMALLOC)) {
91 while (!bio && (nr_vecs /= 2))
92 bio = bio_alloc(gfp_flags, nr_vecs);
93 }
94
95 if (bio) {
96 bio->bi_bdev = bdev;
97 bio->bi_sector = first_sector;
98 }
99 return bio;
100 }
101
102 /*
103 * support function for mpage_readpages. The fs supplied get_block might
104 * return an up to date buffer. This is used to map that buffer into
105 * the page, which allows readpage to avoid triggering a duplicate call
106 * to get_block.
107 *
108 * The idea is to avoid adding buffers to pages that don't already have
109 * them. So when the buffer is up to date and the page size == block size,
110 * this marks the page up to date instead of adding new buffers.
111 */
112 static void
113 map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
114 {
115 struct inode *inode = page->mapping->host;
116 struct buffer_head *page_bh, *head;
117 int block = 0;
118
119 if (!page_has_buffers(page)) {
120 /*
121 * don't make any buffers if there is only one buffer on
122 * the page and the page just needs to be set up to date
123 */
124 if (inode->i_blkbits == PAGE_CACHE_SHIFT &&
125 buffer_uptodate(bh)) {
126 SetPageUptodate(page);
127 return;
128 }
129 create_empty_buffers(page, 1 << inode->i_blkbits, 0);
130 }
131 head = page_buffers(page);
132 page_bh = head;
133 do {
134 if (block == page_block) {
135 page_bh->b_state = bh->b_state;
136 page_bh->b_bdev = bh->b_bdev;
137 page_bh->b_blocknr = bh->b_blocknr;
138 break;
139 }
140 page_bh = page_bh->b_this_page;
141 block++;
142 } while (page_bh != head);
143 }
144
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
145 /*
146 * This is the worker routine which does all the work of mapping the disk
147 * blocks and constructs largest possible bios, submits them for IO if the
148 * blocks are not contiguous on the disk.
149 *
150 * We pass a buffer_head back and forth and use its buffer_mapped() flag to
151 * represent the validity of its disk mapping and to decide when to do the next
152 * get_block() call.
153 */
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
154 static struct bio *
155 do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
156 sector_t *last_block_in_bio, struct buffer_head *map_bh,
157 unsigned long *first_logical_block, get_block_t get_block)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
158 {
159 struct inode *inode = page->mapping->host;
160 const unsigned blkbits = inode->i_blkbits;
161 const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits;
162 const unsigned blocksize = 1 << blkbits;
163 sector_t block_in_file;
164 sector_t last_block;
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
165 sector_t last_block_in_file;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
166 sector_t blocks[MAX_BUF_PER_PAGE];
167 unsigned page_block;
168 unsigned first_hole = blocks_per_page;
169 struct block_device *bdev = NULL;
170 int length;
171 int fully_mapped = 1;
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
172 unsigned nblocks;
173 unsigned relative_block;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
174
175 if (page_has_buffers(page))
176 goto confused;
177
54b21a7 [PATCH] fix possible PAGE_CACHE_SHIFT overflows
Andrew Morton authored
178 block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
179 last_block = block_in_file + nr_pages * blocks_per_page;
180 last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
181 if (last_block > last_block_in_file)
182 last_block = last_block_in_file;
183 page_block = 0;
184
185 /*
186 * Map blocks using the result from the previous get_blocks call first.
187 */
188 nblocks = map_bh->b_size >> blkbits;
189 if (buffer_mapped(map_bh) && block_in_file > *first_logical_block &&
190 block_in_file < (*first_logical_block + nblocks)) {
191 unsigned map_offset = block_in_file - *first_logical_block;
192 unsigned last = nblocks - map_offset;
193
194 for (relative_block = 0; ; relative_block++) {
195 if (relative_block == last) {
196 clear_buffer_mapped(map_bh);
197 break;
198 }
199 if (page_block == blocks_per_page)
200 break;
201 blocks[page_block] = map_bh->b_blocknr + map_offset +
202 relative_block;
203 page_block++;
204 block_in_file++;
205 }
206 bdev = map_bh->b_bdev;
207 }
208
209 /*
210 * Then do more get_blocks calls until we are done with this page.
211 */
212 map_bh->b_page = page;
213 while (page_block < blocks_per_page) {
214 map_bh->b_state = 0;
215 map_bh->b_size = 0;
1da177e Linux-2.6.12-rc2
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216
217 if (block_in_file < last_block) {
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
218 map_bh->b_size = (last_block-block_in_file) << blkbits;
219 if (get_block(inode, block_in_file, map_bh, 0))
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
220 goto confused;
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
221 *first_logical_block = block_in_file;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
222 }
223
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
224 if (!buffer_mapped(map_bh)) {
1da177e Linux-2.6.12-rc2
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225 fully_mapped = 0;
226 if (first_hole == blocks_per_page)
227 first_hole = page_block;
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
228 page_block++;
229 block_in_file++;
1da177e Linux-2.6.12-rc2
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230 continue;
231 }
232
233 /* some filesystems will copy data into the page during
234 * the get_block call, in which case we don't want to
235 * read it again. map_buffer_to_page copies the data
236 * we just collected from get_block into the page's buffers
237 * so readpage doesn't have to repeat the get_block call
238 */
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
239 if (buffer_uptodate(map_bh)) {
240 map_buffer_to_page(page, map_bh, page_block);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
241 goto confused;
242 }
243
244 if (first_hole != blocks_per_page)
245 goto confused; /* hole -> non-hole */
246
247 /* Contiguous blocks? */
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
248 if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
249 goto confused;
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
250 nblocks = map_bh->b_size >> blkbits;
251 for (relative_block = 0; ; relative_block++) {
252 if (relative_block == nblocks) {
253 clear_buffer_mapped(map_bh);
254 break;
255 } else if (page_block == blocks_per_page)
256 break;
257 blocks[page_block] = map_bh->b_blocknr+relative_block;
258 page_block++;
259 block_in_file++;
260 }
261 bdev = map_bh->b_bdev;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
262 }
263
264 if (first_hole != blocks_per_page) {
eebd2aa Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user
Christoph Lameter authored
265 zero_user_segment(page, first_hole << blkbits, PAGE_CACHE_SIZE);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
266 if (first_hole == 0) {
267 SetPageUptodate(page);
268 unlock_page(page);
269 goto out;
270 }
271 } else if (fully_mapped) {
272 SetPageMappedToDisk(page);
273 }
274
c515e1f mm/fs: add hooks to support cleancache
Dan Magenheimer authored
275 if (fully_mapped && blocks_per_page == 1 && !PageUptodate(page) &&
276 cleancache_get_page(page) == 0) {
277 SetPageUptodate(page);
278 goto confused;
279 }
280
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
281 /*
282 * This page will go to BIO. Do we need to send this BIO off first?
283 */
284 if (bio && (*last_block_in_bio != blocks[0] - 1))
285 bio = mpage_bio_submit(READ, bio);
286
287 alloc_new:
288 if (bio == NULL) {
289 bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
290 min_t(int, nr_pages, bio_get_nr_vecs(bdev)),
291 GFP_KERNEL);
292 if (bio == NULL)
293 goto confused;
294 }
295
296 length = first_hole << blkbits;
297 if (bio_add_page(bio, page, length, 0) < length) {
298 bio = mpage_bio_submit(READ, bio);
299 goto alloc_new;
300 }
301
38c8e61 do_mpage_readpage(): don't submit lots of small bios on boundary
Miquel van Smoorenburg authored
302 relative_block = block_in_file - *first_logical_block;
303 nblocks = map_bh->b_size >> blkbits;
304 if ((buffer_boundary(map_bh) && relative_block == nblocks) ||
305 (first_hole != blocks_per_page))
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
306 bio = mpage_bio_submit(READ, bio);
307 else
308 *last_block_in_bio = blocks[blocks_per_page - 1];
309 out:
310 return bio;
311
312 confused:
313 if (bio)
314 bio = mpage_bio_submit(READ, bio);
315 if (!PageUptodate(page))
316 block_read_full_page(page, get_block);
317 else
318 unlock_page(page);
319 goto out;
320 }
321
67be2dd @tali [PATCH] DocBook: fix some descriptions
tali authored
322 /**
78a4a50 docbook: fix filesystems.tmpl source files
Randy Dunlap authored
323 * mpage_readpages - populate an address space with some pages & start reads against them
67be2dd @tali [PATCH] DocBook: fix some descriptions
tali authored
324 * @mapping: the address_space
325 * @pages: The address of a list_head which contains the target pages. These
326 * pages have their ->index populated and are otherwise uninitialised.
327 * The page at @pages->prev has the lowest file offset, and reads should be
328 * issued in @pages->prev to @pages->next order.
329 * @nr_pages: The number of pages at *@pages
330 * @get_block: The filesystem's block mapper function.
331 *
332 * This function walks the pages and the blocks within each page, building and
333 * emitting large BIOs.
334 *
335 * If anything unusual happens, such as:
336 *
337 * - encountering a page which has buffers
338 * - encountering a page which has a non-hole after a hole
339 * - encountering a page with non-contiguous blocks
340 *
341 * then this code just gives up and calls the buffer_head-based read function.
342 * It does handle a page which has holes at the end - that is a common case:
343 * the end-of-file on blocksize < PAGE_CACHE_SIZE setups.
344 *
345 * BH_Boundary explanation:
346 *
347 * There is a problem. The mpage read code assembles several pages, gets all
348 * their disk mappings, and then submits them all. That's fine, but obtaining
349 * the disk mappings may require I/O. Reads of indirect blocks, for example.
350 *
351 * So an mpage read of the first 16 blocks of an ext2 file will cause I/O to be
352 * submitted in the following order:
353 * 12 0 1 2 3 4 5 6 7 8 9 10 11 13 14 15 16
78a4a50 docbook: fix filesystems.tmpl source files
Randy Dunlap authored
354 *
67be2dd @tali [PATCH] DocBook: fix some descriptions
tali authored
355 * because the indirect block has to be read to get the mappings of blocks
356 * 13,14,15,16. Obviously, this impacts performance.
357 *
358 * So what we do it to allow the filesystem's get_block() function to set
359 * BH_Boundary when it maps block 11. BH_Boundary says: mapping of the block
360 * after this one will require I/O against a block which is probably close to
361 * this one. So you should push what I/O you have currently accumulated.
362 *
363 * This all causes the disk requests to be issued in the correct order.
364 */
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
365 int
366 mpage_readpages(struct address_space *mapping, struct list_head *pages,
367 unsigned nr_pages, get_block_t get_block)
368 {
369 struct bio *bio = NULL;
370 unsigned page_idx;
371 sector_t last_block_in_bio = 0;
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
372 struct buffer_head map_bh;
373 unsigned long first_logical_block = 0;
2ed1a6b fs: make mpage read/write_pages() plug
Jens Axboe authored
374 struct blk_plug plug;
375
376 blk_start_plug(&plug);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
377
79ffab3 @kvaneesh ext4: Properly initialize the buffer_head state
kvaneesh authored
378 map_bh.b_state = 0;
379 map_bh.b_size = 0;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
380 for (page_idx = 0; page_idx < nr_pages; page_idx++) {
381 struct page *page = list_entry(pages->prev, struct page, lru);
382
383 prefetchw(&page->flags);
384 list_del(&page->lru);
eb2be18 mm: buffered write cleanup
Nick Piggin authored
385 if (!add_to_page_cache_lru(page, mapping,
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
386 page->index, GFP_KERNEL)) {
387 bio = do_mpage_readpage(bio, page,
388 nr_pages - page_idx,
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
389 &last_block_in_bio, &map_bh,
390 &first_logical_block,
391 get_block);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
392 }
eb2be18 mm: buffered write cleanup
Nick Piggin authored
393 page_cache_release(page);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
394 }
395 BUG_ON(!list_empty(pages));
396 if (bio)
397 mpage_bio_submit(READ, bio);
2ed1a6b fs: make mpage read/write_pages() plug
Jens Axboe authored
398 blk_finish_plug(&plug);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
399 return 0;
400 }
401 EXPORT_SYMBOL(mpage_readpages);
402
403 /*
404 * This isn't called much at all
405 */
406 int mpage_readpage(struct page *page, get_block_t get_block)
407 {
408 struct bio *bio = NULL;
409 sector_t last_block_in_bio = 0;
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
410 struct buffer_head map_bh;
411 unsigned long first_logical_block = 0;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
412
79ffab3 @kvaneesh ext4: Properly initialize the buffer_head state
kvaneesh authored
413 map_bh.b_state = 0;
414 map_bh.b_size = 0;
fa30bd0 [PATCH] map multiple blocks for mpage_readpages()
Badari Pulavarty authored
415 bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
416 &map_bh, &first_logical_block, get_block);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
417 if (bio)
418 mpage_bio_submit(READ, bio);
419 return 0;
420 }
421 EXPORT_SYMBOL(mpage_readpage);
422
423 /*
424 * Writing is not so simple.
425 *
426 * If the page has buffers then they will be used for obtaining the disk
427 * mapping. We only support pages which are fully mapped-and-dirty, with a
428 * special case for pages which are unmapped at the end: end-of-file.
429 *
430 * If the page has no buffers (preferred) then the page is mapped here.
431 *
432 * If all blocks are found to be contiguous then the page can go into the
433 * BIO. Otherwise fall back to the mapping's writepage().
434 *
435 * FIXME: This code wants an estimate of how many pages are still to be
436 * written, so it can intelligently allocate a suitably-sized BIO. For now,
437 * just allocate full-size (16-page) BIOs.
438 */
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
439
ced117c Remove two unneeded exports and make two symbols static in fs/mpage.c
Dmitri Vorobiev authored
440 struct mpage_data {
441 struct bio *bio;
442 sector_t last_block_in_bio;
443 get_block_t *get_block;
444 unsigned use_writepage;
445 };
446
447 static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
29a814d vfs: add hooks for ext4's delayed allocation support
Alex Tomas authored
448 void *data)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
449 {
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
450 struct mpage_data *mpd = data;
451 struct bio *bio = mpd->bio;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
452 struct address_space *mapping = page->mapping;
453 struct inode *inode = page->mapping->host;
454 const unsigned blkbits = inode->i_blkbits;
455 unsigned long end_index;
456 const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits;
457 sector_t last_block;
458 sector_t block_in_file;
459 sector_t blocks[MAX_BUF_PER_PAGE];
460 unsigned page_block;
461 unsigned first_unmapped = blocks_per_page;
462 struct block_device *bdev = NULL;
463 int boundary = 0;
464 sector_t boundary_block = 0;
465 struct block_device *boundary_bdev = NULL;
466 int length;
467 struct buffer_head map_bh;
468 loff_t i_size = i_size_read(inode);
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
469 int ret = 0;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
470
471 if (page_has_buffers(page)) {
472 struct buffer_head *head = page_buffers(page);
473 struct buffer_head *bh = head;
474
475 /* If they're all mapped and dirty, do it */
476 page_block = 0;
477 do {
478 BUG_ON(buffer_locked(bh));
479 if (!buffer_mapped(bh)) {
480 /*
481 * unmapped dirty buffers are created by
482 * __set_page_dirty_buffers -> mmapped data
483 */
484 if (buffer_dirty(bh))
485 goto confused;
486 if (first_unmapped == blocks_per_page)
487 first_unmapped = page_block;
488 continue;
489 }
490
491 if (first_unmapped != blocks_per_page)
492 goto confused; /* hole -> non-hole */
493
494 if (!buffer_dirty(bh) || !buffer_uptodate(bh))
495 goto confused;
496 if (page_block) {
497 if (bh->b_blocknr != blocks[page_block-1] + 1)
498 goto confused;
499 }
500 blocks[page_block++] = bh->b_blocknr;
501 boundary = buffer_boundary(bh);
502 if (boundary) {
503 boundary_block = bh->b_blocknr;
504 boundary_bdev = bh->b_bdev;
505 }
506 bdev = bh->b_bdev;
507 } while ((bh = bh->b_this_page) != head);
508
509 if (first_unmapped)
510 goto page_is_mapped;
511
512 /*
513 * Page has buffers, but they are all unmapped. The page was
514 * created by pagein or read over a hole which was handled by
515 * block_read_full_page(). If this address_space is also
516 * using mpage_readpages then this can rarely happen.
517 */
518 goto confused;
519 }
520
521 /*
522 * The page has no buffers: map it to disk
523 */
524 BUG_ON(!PageUptodate(page));
54b21a7 [PATCH] fix possible PAGE_CACHE_SHIFT overflows
Andrew Morton authored
525 block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
526 last_block = (i_size - 1) >> blkbits;
527 map_bh.b_page = page;
528 for (page_block = 0; page_block < blocks_per_page; ) {
529
530 map_bh.b_state = 0;
b0cf232 [PATCH] pass b_size to ->get_block()
Badari Pulavarty authored
531 map_bh.b_size = 1 << blkbits;
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
532 if (mpd->get_block(inode, block_in_file, &map_bh, 1))
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
533 goto confused;
534 if (buffer_new(&map_bh))
535 unmap_underlying_metadata(map_bh.b_bdev,
536 map_bh.b_blocknr);
537 if (buffer_boundary(&map_bh)) {
538 boundary_block = map_bh.b_blocknr;
539 boundary_bdev = map_bh.b_bdev;
540 }
541 if (page_block) {
542 if (map_bh.b_blocknr != blocks[page_block-1] + 1)
543 goto confused;
544 }
545 blocks[page_block++] = map_bh.b_blocknr;
546 boundary = buffer_boundary(&map_bh);
547 bdev = map_bh.b_bdev;
548 if (block_in_file == last_block)
549 break;
550 block_in_file++;
551 }
552 BUG_ON(page_block == 0);
553
554 first_unmapped = page_block;
555
556 page_is_mapped:
557 end_index = i_size >> PAGE_CACHE_SHIFT;
558 if (page->index >= end_index) {
559 /*
560 * The page straddles i_size. It must be zeroed out on each
2a61aa4 @adambuchbinder Fix misspellings of "invocation" in comments.
adambuchbinder authored
561 * and every writepage invocation because it may be mmapped.
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
562 * "A file is mapped in multiples of the page size. For a file
563 * that is not a multiple of the page size, the remaining memory
564 * is zeroed when mapped, and writes to that region are not
565 * written out to the file."
566 */
567 unsigned offset = i_size & (PAGE_CACHE_SIZE - 1);
568
569 if (page->index > end_index || !offset)
570 goto confused;
eebd2aa Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user
Christoph Lameter authored
571 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
572 }
573
574 /*
575 * This page will go to BIO. Do we need to send this BIO off first?
576 */
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
577 if (bio && mpd->last_block_in_bio != blocks[0] - 1)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
578 bio = mpage_bio_submit(WRITE, bio);
579
580 alloc_new:
581 if (bio == NULL) {
582 bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
583 bio_get_nr_vecs(bdev), GFP_NOFS|__GFP_HIGH);
584 if (bio == NULL)
585 goto confused;
586 }
587
588 /*
589 * Must try to add the page before marking the buffer clean or
590 * the confused fail path above (OOM) will be very confused when
591 * it finds all bh marked clean (i.e. it will not write anything)
592 */
593 length = first_unmapped << blkbits;
594 if (bio_add_page(bio, page, length, 0) < length) {
595 bio = mpage_bio_submit(WRITE, bio);
596 goto alloc_new;
597 }
598
599 /*
600 * OK, we have our BIO, so we can now mark the buffers clean. Make
601 * sure to only clean buffers which we know we'll be writing.
602 */
603 if (page_has_buffers(page)) {
604 struct buffer_head *head = page_buffers(page);
605 struct buffer_head *bh = head;
606 unsigned buffer_counter = 0;
607
608 do {
609 if (buffer_counter++ == first_unmapped)
610 break;
611 clear_buffer_dirty(bh);
612 bh = bh->b_this_page;
613 } while (bh != head);
614
615 /*
616 * we cannot drop the bh if the page is not uptodate
617 * or a concurrent readpage would fail to serialize with the bh
618 * and it would read from disk before we reach the platter.
619 */
620 if (buffer_heads_over_limit && PageUptodate(page))
621 try_to_free_buffers(page);
622 }
623
624 BUG_ON(PageWriteback(page));
625 set_page_writeback(page);
626 unlock_page(page);
627 if (boundary || (first_unmapped != blocks_per_page)) {
628 bio = mpage_bio_submit(WRITE, bio);
629 if (boundary_block) {
630 write_boundary_block(boundary_bdev,
631 boundary_block, 1 << blkbits);
632 }
633 } else {
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
634 mpd->last_block_in_bio = blocks[blocks_per_page - 1];
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
635 }
636 goto out;
637
638 confused:
639 if (bio)
640 bio = mpage_bio_submit(WRITE, bio);
641
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
642 if (mpd->use_writepage) {
643 ret = mapping->a_ops->writepage(page, wbc);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
644 } else {
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
645 ret = -EAGAIN;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
646 goto out;
647 }
648 /*
649 * The caller has a ref on the inode, so *mapping is stable
650 */
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
651 mapping_set_error(mapping, ret);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
652 out:
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
653 mpd->bio = bio;
654 return ret;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
655 }
656
657 /**
78a4a50 docbook: fix filesystems.tmpl source files
Randy Dunlap authored
658 * mpage_writepages - walk the list of dirty pages of the given address space & writepage() all of them
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
659 * @mapping: address space structure to write
660 * @wbc: subtract the number of written pages from *@wbc->nr_to_write
661 * @get_block: the filesystem's block mapper function.
662 * If this is NULL then use a_ops->writepage. Otherwise, go
663 * direct-to-BIO.
664 *
665 * This is a library function, which implements the writepages()
666 * address_space_operation.
667 *
668 * If a page is already under I/O, generic_writepages() skips it, even
669 * if it's dirty. This is desirable behaviour for memory-cleaning writeback,
670 * but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
671 * and msync() need to guarantee that all the data which was dirty at the time
672 * the call was made get new I/O started against them. If wbc->sync_mode is
673 * WB_SYNC_ALL then we were called for data integrity and we must wait for
674 * existing IO to complete.
675 */
676 int
677 mpage_writepages(struct address_space *mapping,
678 struct writeback_control *wbc, get_block_t get_block)
679 {
2ed1a6b fs: make mpage read/write_pages() plug
Jens Axboe authored
680 struct blk_plug plug;
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
681 int ret;
682
2ed1a6b fs: make mpage read/write_pages() plug
Jens Axboe authored
683 blk_start_plug(&plug);
684
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
685 if (!get_block)
686 ret = generic_writepages(mapping, wbc);
687 else {
688 struct mpage_data mpd = {
689 .bio = NULL,
690 .last_block_in_bio = 0,
691 .get_block = get_block,
692 .use_writepage = 1,
693 };
694
695 ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd);
696 if (mpd.bio)
697 mpage_bio_submit(WRITE, mpd.bio);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
698 }
2ed1a6b fs: make mpage read/write_pages() plug
Jens Axboe authored
699 blk_finish_plug(&plug);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
700 return ret;
701 }
702 EXPORT_SYMBOL(mpage_writepages);
703
704 int mpage_writepage(struct page *page, get_block_t get_block,
705 struct writeback_control *wbc)
706 {
0ea9718 consolidate generic_writepages and mpage_writepages
Miklos Szeredi authored
707 struct mpage_data mpd = {
708 .bio = NULL,
709 .last_block_in_bio = 0,
710 .get_block = get_block,
711 .use_writepage = 0,
712 };
713 int ret = __mpage_writepage(page, wbc, &mpd);
714 if (mpd.bio)
715 mpage_bio_submit(WRITE, mpd.bio);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
716 return ret;
717 }
718 EXPORT_SYMBOL(mpage_writepage);
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