Commit | Line | Data |
---|---|---|
1da177e4 LT |
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 | * | |
e1f8e874 | 9 | * 15May2002 Andrew Morton |
1da177e4 LT |
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> | |
630d9c47 | 16 | #include <linux/export.h> |
1da177e4 LT |
17 | #include <linux/mm.h> |
18 | #include <linux/kdev_t.h> | |
5a0e3ad6 | 19 | #include <linux/gfp.h> |
1da177e4 LT |
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> | |
c515e1fd | 30 | #include <linux/cleancache.h> |
4db96b71 | 31 | #include "internal.h" |
1da177e4 | 32 | |
32cbbe59 MS |
33 | #define CREATE_TRACE_POINTS |
34 | #include <trace/events/android_fs.h> | |
35 | ||
36 | EXPORT_TRACEPOINT_SYMBOL(android_fs_datawrite_start); | |
37 | EXPORT_TRACEPOINT_SYMBOL(android_fs_datawrite_end); | |
38 | EXPORT_TRACEPOINT_SYMBOL(android_fs_dataread_start); | |
39 | EXPORT_TRACEPOINT_SYMBOL(android_fs_dataread_end); | |
40 | ||
1da177e4 LT |
41 | /* |
42 | * I/O completion handler for multipage BIOs. | |
43 | * | |
44 | * The mpage code never puts partial pages into a BIO (except for end-of-file). | |
45 | * If a page does not map to a contiguous run of blocks then it simply falls | |
46 | * back to block_read_full_page(). | |
47 | * | |
48 | * Why is this? If a page's completion depends on a number of different BIOs | |
49 | * which can complete in any order (or at the same time) then determining the | |
50 | * status of that page is hard. See end_buffer_async_read() for the details. | |
51 | * There is no point in duplicating all that complexity. | |
52 | */ | |
4246a0b6 | 53 | static void mpage_end_io(struct bio *bio) |
1da177e4 | 54 | { |
2c30c71b KO |
55 | struct bio_vec *bv; |
56 | int i; | |
1da177e4 | 57 | |
32cbbe59 MS |
58 | if (trace_android_fs_dataread_end_enabled() && |
59 | (bio_data_dir(bio) == READ)) { | |
60 | struct page *first_page = bio->bi_io_vec[0].bv_page; | |
61 | ||
62 | if (first_page != NULL) | |
63 | trace_android_fs_dataread_end(first_page->mapping->host, | |
64 | page_offset(first_page), | |
65 | bio->bi_iter.bi_size); | |
66 | } | |
67 | ||
2c30c71b KO |
68 | bio_for_each_segment_all(bv, bio, i) { |
69 | struct page *page = bv->bv_page; | |
4246a0b6 | 70 | page_endio(page, bio_data_dir(bio), bio->bi_error); |
2c30c71b KO |
71 | } |
72 | ||
1da177e4 | 73 | bio_put(bio); |
1da177e4 LT |
74 | } |
75 | ||
ced117c7 | 76 | static struct bio *mpage_bio_submit(int rw, struct bio *bio) |
1da177e4 | 77 | { |
32cbbe59 MS |
78 | if (trace_android_fs_dataread_start_enabled() && (rw == READ)) { |
79 | struct page *first_page = bio->bi_io_vec[0].bv_page; | |
80 | ||
81 | if (first_page != NULL) { | |
d854b688 MS |
82 | char *path, pathbuf[MAX_TRACE_PATHBUF_LEN]; |
83 | ||
84 | path = android_fstrace_get_pathname(pathbuf, | |
85 | MAX_TRACE_PATHBUF_LEN, | |
86 | first_page->mapping->host); | |
32cbbe59 MS |
87 | trace_android_fs_dataread_start( |
88 | first_page->mapping->host, | |
89 | page_offset(first_page), | |
90 | bio->bi_iter.bi_size, | |
91 | current->pid, | |
d854b688 | 92 | path, |
32cbbe59 MS |
93 | current->comm); |
94 | } | |
95 | } | |
c32b0d4b | 96 | bio->bi_end_io = mpage_end_io; |
4db96b71 | 97 | guard_bio_eod(rw, bio); |
1da177e4 LT |
98 | submit_bio(rw, bio); |
99 | return NULL; | |
100 | } | |
101 | ||
102 | static struct bio * | |
103 | mpage_alloc(struct block_device *bdev, | |
104 | sector_t first_sector, int nr_vecs, | |
dd0fc66f | 105 | gfp_t gfp_flags) |
1da177e4 LT |
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; | |
4f024f37 | 118 | bio->bi_iter.bi_sector = first_sector; |
1da177e4 LT |
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 | */ | |
133 | static void | |
134 | map_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 | } | |
04447026 | 150 | create_empty_buffers(page, i_blocksize(inode), 0); |
1da177e4 LT |
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 | ||
fa30bd05 BP |
166 | /* |
167 | * This is the worker routine which does all the work of mapping the disk | |
168 | * blocks and constructs largest possible bios, submits them for IO if the | |
169 | * blocks are not contiguous on the disk. | |
170 | * | |
171 | * We pass a buffer_head back and forth and use its buffer_mapped() flag to | |
172 | * represent the validity of its disk mapping and to decide when to do the next | |
173 | * get_block() call. | |
174 | */ | |
1da177e4 LT |
175 | static struct bio * |
176 | do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages, | |
fa30bd05 | 177 | sector_t *last_block_in_bio, struct buffer_head *map_bh, |
063d99b4 MH |
178 | unsigned long *first_logical_block, get_block_t get_block, |
179 | gfp_t gfp) | |
1da177e4 LT |
180 | { |
181 | struct inode *inode = page->mapping->host; | |
182 | const unsigned blkbits = inode->i_blkbits; | |
183 | const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits; | |
184 | const unsigned blocksize = 1 << blkbits; | |
185 | sector_t block_in_file; | |
186 | sector_t last_block; | |
fa30bd05 | 187 | sector_t last_block_in_file; |
1da177e4 LT |
188 | sector_t blocks[MAX_BUF_PER_PAGE]; |
189 | unsigned page_block; | |
190 | unsigned first_hole = blocks_per_page; | |
191 | struct block_device *bdev = NULL; | |
1da177e4 LT |
192 | int length; |
193 | int fully_mapped = 1; | |
fa30bd05 BP |
194 | unsigned nblocks; |
195 | unsigned relative_block; | |
1da177e4 LT |
196 | |
197 | if (page_has_buffers(page)) | |
198 | goto confused; | |
199 | ||
54b21a79 | 200 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); |
fa30bd05 BP |
201 | last_block = block_in_file + nr_pages * blocks_per_page; |
202 | last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits; | |
203 | if (last_block > last_block_in_file) | |
204 | last_block = last_block_in_file; | |
205 | page_block = 0; | |
206 | ||
207 | /* | |
208 | * Map blocks using the result from the previous get_blocks call first. | |
209 | */ | |
210 | nblocks = map_bh->b_size >> blkbits; | |
211 | if (buffer_mapped(map_bh) && block_in_file > *first_logical_block && | |
212 | block_in_file < (*first_logical_block + nblocks)) { | |
213 | unsigned map_offset = block_in_file - *first_logical_block; | |
214 | unsigned last = nblocks - map_offset; | |
215 | ||
216 | for (relative_block = 0; ; relative_block++) { | |
217 | if (relative_block == last) { | |
218 | clear_buffer_mapped(map_bh); | |
219 | break; | |
220 | } | |
221 | if (page_block == blocks_per_page) | |
222 | break; | |
223 | blocks[page_block] = map_bh->b_blocknr + map_offset + | |
224 | relative_block; | |
225 | page_block++; | |
226 | block_in_file++; | |
227 | } | |
228 | bdev = map_bh->b_bdev; | |
229 | } | |
230 | ||
231 | /* | |
232 | * Then do more get_blocks calls until we are done with this page. | |
233 | */ | |
234 | map_bh->b_page = page; | |
235 | while (page_block < blocks_per_page) { | |
236 | map_bh->b_state = 0; | |
237 | map_bh->b_size = 0; | |
1da177e4 | 238 | |
1da177e4 | 239 | if (block_in_file < last_block) { |
fa30bd05 BP |
240 | map_bh->b_size = (last_block-block_in_file) << blkbits; |
241 | if (get_block(inode, block_in_file, map_bh, 0)) | |
1da177e4 | 242 | goto confused; |
fa30bd05 | 243 | *first_logical_block = block_in_file; |
1da177e4 LT |
244 | } |
245 | ||
fa30bd05 | 246 | if (!buffer_mapped(map_bh)) { |
1da177e4 LT |
247 | fully_mapped = 0; |
248 | if (first_hole == blocks_per_page) | |
249 | first_hole = page_block; | |
fa30bd05 BP |
250 | page_block++; |
251 | block_in_file++; | |
1da177e4 LT |
252 | continue; |
253 | } | |
254 | ||
255 | /* some filesystems will copy data into the page during | |
256 | * the get_block call, in which case we don't want to | |
257 | * read it again. map_buffer_to_page copies the data | |
258 | * we just collected from get_block into the page's buffers | |
259 | * so readpage doesn't have to repeat the get_block call | |
260 | */ | |
fa30bd05 BP |
261 | if (buffer_uptodate(map_bh)) { |
262 | map_buffer_to_page(page, map_bh, page_block); | |
1da177e4 LT |
263 | goto confused; |
264 | } | |
265 | ||
266 | if (first_hole != blocks_per_page) | |
267 | goto confused; /* hole -> non-hole */ | |
268 | ||
269 | /* Contiguous blocks? */ | |
fa30bd05 | 270 | if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1) |
1da177e4 | 271 | goto confused; |
fa30bd05 BP |
272 | nblocks = map_bh->b_size >> blkbits; |
273 | for (relative_block = 0; ; relative_block++) { | |
274 | if (relative_block == nblocks) { | |
275 | clear_buffer_mapped(map_bh); | |
276 | break; | |
277 | } else if (page_block == blocks_per_page) | |
278 | break; | |
279 | blocks[page_block] = map_bh->b_blocknr+relative_block; | |
280 | page_block++; | |
281 | block_in_file++; | |
282 | } | |
283 | bdev = map_bh->b_bdev; | |
1da177e4 LT |
284 | } |
285 | ||
286 | if (first_hole != blocks_per_page) { | |
eebd2aa3 | 287 | zero_user_segment(page, first_hole << blkbits, PAGE_CACHE_SIZE); |
1da177e4 LT |
288 | if (first_hole == 0) { |
289 | SetPageUptodate(page); | |
290 | unlock_page(page); | |
291 | goto out; | |
292 | } | |
293 | } else if (fully_mapped) { | |
294 | SetPageMappedToDisk(page); | |
295 | } | |
296 | ||
c515e1fd DM |
297 | if (fully_mapped && blocks_per_page == 1 && !PageUptodate(page) && |
298 | cleancache_get_page(page) == 0) { | |
299 | SetPageUptodate(page); | |
300 | goto confused; | |
301 | } | |
302 | ||
1da177e4 LT |
303 | /* |
304 | * This page will go to BIO. Do we need to send this BIO off first? | |
305 | */ | |
306 | if (bio && (*last_block_in_bio != blocks[0] - 1)) | |
307 | bio = mpage_bio_submit(READ, bio); | |
308 | ||
309 | alloc_new: | |
310 | if (bio == NULL) { | |
47a191fd MW |
311 | if (first_hole == blocks_per_page) { |
312 | if (!bdev_read_page(bdev, blocks[0] << (blkbits - 9), | |
313 | page)) | |
314 | goto out; | |
315 | } | |
1da177e4 | 316 | bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9), |
063d99b4 | 317 | min_t(int, nr_pages, BIO_MAX_PAGES), gfp); |
1da177e4 LT |
318 | if (bio == NULL) |
319 | goto confused; | |
320 | } | |
321 | ||
322 | length = first_hole << blkbits; | |
323 | if (bio_add_page(bio, page, length, 0) < length) { | |
324 | bio = mpage_bio_submit(READ, bio); | |
325 | goto alloc_new; | |
326 | } | |
327 | ||
38c8e618 MS |
328 | relative_block = block_in_file - *first_logical_block; |
329 | nblocks = map_bh->b_size >> blkbits; | |
330 | if ((buffer_boundary(map_bh) && relative_block == nblocks) || | |
331 | (first_hole != blocks_per_page)) | |
1da177e4 LT |
332 | bio = mpage_bio_submit(READ, bio); |
333 | else | |
334 | *last_block_in_bio = blocks[blocks_per_page - 1]; | |
335 | out: | |
336 | return bio; | |
337 | ||
338 | confused: | |
339 | if (bio) | |
340 | bio = mpage_bio_submit(READ, bio); | |
341 | if (!PageUptodate(page)) | |
342 | block_read_full_page(page, get_block); | |
343 | else | |
344 | unlock_page(page); | |
345 | goto out; | |
346 | } | |
347 | ||
67be2dd1 | 348 | /** |
78a4a50a | 349 | * mpage_readpages - populate an address space with some pages & start reads against them |
67be2dd1 MW |
350 | * @mapping: the address_space |
351 | * @pages: The address of a list_head which contains the target pages. These | |
352 | * pages have their ->index populated and are otherwise uninitialised. | |
67be2dd1 MW |
353 | * The page at @pages->prev has the lowest file offset, and reads should be |
354 | * issued in @pages->prev to @pages->next order. | |
67be2dd1 MW |
355 | * @nr_pages: The number of pages at *@pages |
356 | * @get_block: The filesystem's block mapper function. | |
357 | * | |
358 | * This function walks the pages and the blocks within each page, building and | |
359 | * emitting large BIOs. | |
360 | * | |
361 | * If anything unusual happens, such as: | |
362 | * | |
363 | * - encountering a page which has buffers | |
364 | * - encountering a page which has a non-hole after a hole | |
365 | * - encountering a page with non-contiguous blocks | |
366 | * | |
367 | * then this code just gives up and calls the buffer_head-based read function. | |
368 | * It does handle a page which has holes at the end - that is a common case: | |
369 | * the end-of-file on blocksize < PAGE_CACHE_SIZE setups. | |
370 | * | |
371 | * BH_Boundary explanation: | |
372 | * | |
373 | * There is a problem. The mpage read code assembles several pages, gets all | |
374 | * their disk mappings, and then submits them all. That's fine, but obtaining | |
375 | * the disk mappings may require I/O. Reads of indirect blocks, for example. | |
376 | * | |
377 | * So an mpage read of the first 16 blocks of an ext2 file will cause I/O to be | |
378 | * submitted in the following order: | |
379 | * 12 0 1 2 3 4 5 6 7 8 9 10 11 13 14 15 16 | |
78a4a50a | 380 | * |
67be2dd1 MW |
381 | * because the indirect block has to be read to get the mappings of blocks |
382 | * 13,14,15,16. Obviously, this impacts performance. | |
383 | * | |
384 | * So what we do it to allow the filesystem's get_block() function to set | |
385 | * BH_Boundary when it maps block 11. BH_Boundary says: mapping of the block | |
386 | * after this one will require I/O against a block which is probably close to | |
387 | * this one. So you should push what I/O you have currently accumulated. | |
388 | * | |
389 | * This all causes the disk requests to be issued in the correct order. | |
390 | */ | |
1da177e4 LT |
391 | int |
392 | mpage_readpages(struct address_space *mapping, struct list_head *pages, | |
393 | unsigned nr_pages, get_block_t get_block) | |
394 | { | |
395 | struct bio *bio = NULL; | |
396 | unsigned page_idx; | |
397 | sector_t last_block_in_bio = 0; | |
fa30bd05 BP |
398 | struct buffer_head map_bh; |
399 | unsigned long first_logical_block = 0; | |
c62d2555 | 400 | gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL); |
1da177e4 | 401 | |
79ffab34 AK |
402 | map_bh.b_state = 0; |
403 | map_bh.b_size = 0; | |
1da177e4 LT |
404 | for (page_idx = 0; page_idx < nr_pages; page_idx++) { |
405 | struct page *page = list_entry(pages->prev, struct page, lru); | |
406 | ||
407 | prefetchw(&page->flags); | |
408 | list_del(&page->lru); | |
eb2be189 | 409 | if (!add_to_page_cache_lru(page, mapping, |
063d99b4 MH |
410 | page->index, |
411 | gfp)) { | |
1da177e4 LT |
412 | bio = do_mpage_readpage(bio, page, |
413 | nr_pages - page_idx, | |
fa30bd05 BP |
414 | &last_block_in_bio, &map_bh, |
415 | &first_logical_block, | |
063d99b4 | 416 | get_block, gfp); |
1da177e4 | 417 | } |
eb2be189 | 418 | page_cache_release(page); |
1da177e4 | 419 | } |
1da177e4 LT |
420 | BUG_ON(!list_empty(pages)); |
421 | if (bio) | |
422 | mpage_bio_submit(READ, bio); | |
423 | return 0; | |
424 | } | |
425 | EXPORT_SYMBOL(mpage_readpages); | |
426 | ||
427 | /* | |
428 | * This isn't called much at all | |
429 | */ | |
430 | int mpage_readpage(struct page *page, get_block_t get_block) | |
431 | { | |
432 | struct bio *bio = NULL; | |
433 | sector_t last_block_in_bio = 0; | |
fa30bd05 BP |
434 | struct buffer_head map_bh; |
435 | unsigned long first_logical_block = 0; | |
c62d2555 | 436 | gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL); |
1da177e4 | 437 | |
79ffab34 AK |
438 | map_bh.b_state = 0; |
439 | map_bh.b_size = 0; | |
fa30bd05 | 440 | bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio, |
063d99b4 | 441 | &map_bh, &first_logical_block, get_block, gfp); |
1da177e4 LT |
442 | if (bio) |
443 | mpage_bio_submit(READ, bio); | |
444 | return 0; | |
445 | } | |
446 | EXPORT_SYMBOL(mpage_readpage); | |
447 | ||
448 | /* | |
449 | * Writing is not so simple. | |
450 | * | |
451 | * If the page has buffers then they will be used for obtaining the disk | |
452 | * mapping. We only support pages which are fully mapped-and-dirty, with a | |
453 | * special case for pages which are unmapped at the end: end-of-file. | |
454 | * | |
455 | * If the page has no buffers (preferred) then the page is mapped here. | |
456 | * | |
457 | * If all blocks are found to be contiguous then the page can go into the | |
458 | * BIO. Otherwise fall back to the mapping's writepage(). | |
459 | * | |
460 | * FIXME: This code wants an estimate of how many pages are still to be | |
461 | * written, so it can intelligently allocate a suitably-sized BIO. For now, | |
462 | * just allocate full-size (16-page) BIOs. | |
463 | */ | |
0ea97180 | 464 | |
ced117c7 DV |
465 | struct mpage_data { |
466 | struct bio *bio; | |
467 | sector_t last_block_in_bio; | |
468 | get_block_t *get_block; | |
469 | unsigned use_writepage; | |
470 | }; | |
471 | ||
90768eee MW |
472 | /* |
473 | * We have our BIO, so we can now mark the buffers clean. Make | |
474 | * sure to only clean buffers which we know we'll be writing. | |
475 | */ | |
476 | static void clean_buffers(struct page *page, unsigned first_unmapped) | |
477 | { | |
478 | unsigned buffer_counter = 0; | |
479 | struct buffer_head *bh, *head; | |
480 | if (!page_has_buffers(page)) | |
481 | return; | |
482 | head = page_buffers(page); | |
483 | bh = head; | |
484 | ||
485 | do { | |
486 | if (buffer_counter++ == first_unmapped) | |
487 | break; | |
488 | clear_buffer_dirty(bh); | |
489 | bh = bh->b_this_page; | |
490 | } while (bh != head); | |
491 | ||
492 | /* | |
493 | * we cannot drop the bh if the page is not uptodate or a concurrent | |
494 | * readpage would fail to serialize with the bh and it would read from | |
495 | * disk before we reach the platter. | |
496 | */ | |
497 | if (buffer_heads_over_limit && PageUptodate(page)) | |
498 | try_to_free_buffers(page); | |
499 | } | |
500 | ||
ced117c7 | 501 | static int __mpage_writepage(struct page *page, struct writeback_control *wbc, |
29a814d2 | 502 | void *data) |
1da177e4 | 503 | { |
0ea97180 MS |
504 | struct mpage_data *mpd = data; |
505 | struct bio *bio = mpd->bio; | |
1da177e4 LT |
506 | struct address_space *mapping = page->mapping; |
507 | struct inode *inode = page->mapping->host; | |
508 | const unsigned blkbits = inode->i_blkbits; | |
509 | unsigned long end_index; | |
510 | const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits; | |
511 | sector_t last_block; | |
512 | sector_t block_in_file; | |
513 | sector_t blocks[MAX_BUF_PER_PAGE]; | |
514 | unsigned page_block; | |
515 | unsigned first_unmapped = blocks_per_page; | |
516 | struct block_device *bdev = NULL; | |
517 | int boundary = 0; | |
518 | sector_t boundary_block = 0; | |
519 | struct block_device *boundary_bdev = NULL; | |
520 | int length; | |
521 | struct buffer_head map_bh; | |
522 | loff_t i_size = i_size_read(inode); | |
0ea97180 | 523 | int ret = 0; |
5948edbc | 524 | int wr = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE); |
1da177e4 LT |
525 | |
526 | if (page_has_buffers(page)) { | |
527 | struct buffer_head *head = page_buffers(page); | |
528 | struct buffer_head *bh = head; | |
529 | ||
530 | /* If they're all mapped and dirty, do it */ | |
531 | page_block = 0; | |
532 | do { | |
533 | BUG_ON(buffer_locked(bh)); | |
534 | if (!buffer_mapped(bh)) { | |
535 | /* | |
536 | * unmapped dirty buffers are created by | |
537 | * __set_page_dirty_buffers -> mmapped data | |
538 | */ | |
539 | if (buffer_dirty(bh)) | |
540 | goto confused; | |
541 | if (first_unmapped == blocks_per_page) | |
542 | first_unmapped = page_block; | |
543 | continue; | |
544 | } | |
545 | ||
546 | if (first_unmapped != blocks_per_page) | |
547 | goto confused; /* hole -> non-hole */ | |
548 | ||
549 | if (!buffer_dirty(bh) || !buffer_uptodate(bh)) | |
550 | goto confused; | |
551 | if (page_block) { | |
552 | if (bh->b_blocknr != blocks[page_block-1] + 1) | |
553 | goto confused; | |
554 | } | |
555 | blocks[page_block++] = bh->b_blocknr; | |
556 | boundary = buffer_boundary(bh); | |
557 | if (boundary) { | |
558 | boundary_block = bh->b_blocknr; | |
559 | boundary_bdev = bh->b_bdev; | |
560 | } | |
561 | bdev = bh->b_bdev; | |
562 | } while ((bh = bh->b_this_page) != head); | |
563 | ||
564 | if (first_unmapped) | |
565 | goto page_is_mapped; | |
566 | ||
567 | /* | |
568 | * Page has buffers, but they are all unmapped. The page was | |
569 | * created by pagein or read over a hole which was handled by | |
570 | * block_read_full_page(). If this address_space is also | |
571 | * using mpage_readpages then this can rarely happen. | |
572 | */ | |
573 | goto confused; | |
574 | } | |
575 | ||
576 | /* | |
577 | * The page has no buffers: map it to disk | |
578 | */ | |
579 | BUG_ON(!PageUptodate(page)); | |
54b21a79 | 580 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); |
1da177e4 LT |
581 | last_block = (i_size - 1) >> blkbits; |
582 | map_bh.b_page = page; | |
583 | for (page_block = 0; page_block < blocks_per_page; ) { | |
584 | ||
585 | map_bh.b_state = 0; | |
b0cf2321 | 586 | map_bh.b_size = 1 << blkbits; |
0ea97180 | 587 | if (mpd->get_block(inode, block_in_file, &map_bh, 1)) |
1da177e4 LT |
588 | goto confused; |
589 | if (buffer_new(&map_bh)) | |
590 | unmap_underlying_metadata(map_bh.b_bdev, | |
591 | map_bh.b_blocknr); | |
592 | if (buffer_boundary(&map_bh)) { | |
593 | boundary_block = map_bh.b_blocknr; | |
594 | boundary_bdev = map_bh.b_bdev; | |
595 | } | |
596 | if (page_block) { | |
597 | if (map_bh.b_blocknr != blocks[page_block-1] + 1) | |
598 | goto confused; | |
599 | } | |
600 | blocks[page_block++] = map_bh.b_blocknr; | |
601 | boundary = buffer_boundary(&map_bh); | |
602 | bdev = map_bh.b_bdev; | |
603 | if (block_in_file == last_block) | |
604 | break; | |
605 | block_in_file++; | |
606 | } | |
607 | BUG_ON(page_block == 0); | |
608 | ||
609 | first_unmapped = page_block; | |
610 | ||
611 | page_is_mapped: | |
612 | end_index = i_size >> PAGE_CACHE_SHIFT; | |
613 | if (page->index >= end_index) { | |
614 | /* | |
615 | * The page straddles i_size. It must be zeroed out on each | |
2a61aa40 | 616 | * and every writepage invocation because it may be mmapped. |
1da177e4 LT |
617 | * "A file is mapped in multiples of the page size. For a file |
618 | * that is not a multiple of the page size, the remaining memory | |
619 | * is zeroed when mapped, and writes to that region are not | |
620 | * written out to the file." | |
621 | */ | |
622 | unsigned offset = i_size & (PAGE_CACHE_SIZE - 1); | |
1da177e4 LT |
623 | |
624 | if (page->index > end_index || !offset) | |
625 | goto confused; | |
eebd2aa3 | 626 | zero_user_segment(page, offset, PAGE_CACHE_SIZE); |
1da177e4 LT |
627 | } |
628 | ||
629 | /* | |
630 | * This page will go to BIO. Do we need to send this BIO off first? | |
631 | */ | |
0ea97180 | 632 | if (bio && mpd->last_block_in_bio != blocks[0] - 1) |
5948edbc | 633 | bio = mpage_bio_submit(wr, bio); |
1da177e4 LT |
634 | |
635 | alloc_new: | |
636 | if (bio == NULL) { | |
47a191fd MW |
637 | if (first_unmapped == blocks_per_page) { |
638 | if (!bdev_write_page(bdev, blocks[0] << (blkbits - 9), | |
639 | page, wbc)) { | |
640 | clean_buffers(page, first_unmapped); | |
641 | goto out; | |
642 | } | |
643 | } | |
1da177e4 | 644 | bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9), |
b54ffb73 | 645 | BIO_MAX_PAGES, GFP_NOFS|__GFP_HIGH); |
1da177e4 LT |
646 | if (bio == NULL) |
647 | goto confused; | |
429b3fb0 | 648 | |
b16b1deb | 649 | wbc_init_bio(wbc, bio); |
1da177e4 LT |
650 | } |
651 | ||
652 | /* | |
653 | * Must try to add the page before marking the buffer clean or | |
654 | * the confused fail path above (OOM) will be very confused when | |
655 | * it finds all bh marked clean (i.e. it will not write anything) | |
656 | */ | |
2a814908 | 657 | wbc_account_io(wbc, page, PAGE_SIZE); |
1da177e4 LT |
658 | length = first_unmapped << blkbits; |
659 | if (bio_add_page(bio, page, length, 0) < length) { | |
5948edbc | 660 | bio = mpage_bio_submit(wr, bio); |
1da177e4 LT |
661 | goto alloc_new; |
662 | } | |
663 | ||
90768eee | 664 | clean_buffers(page, first_unmapped); |
1da177e4 LT |
665 | |
666 | BUG_ON(PageWriteback(page)); | |
667 | set_page_writeback(page); | |
668 | unlock_page(page); | |
669 | if (boundary || (first_unmapped != blocks_per_page)) { | |
5948edbc | 670 | bio = mpage_bio_submit(wr, bio); |
1da177e4 LT |
671 | if (boundary_block) { |
672 | write_boundary_block(boundary_bdev, | |
673 | boundary_block, 1 << blkbits); | |
674 | } | |
675 | } else { | |
0ea97180 | 676 | mpd->last_block_in_bio = blocks[blocks_per_page - 1]; |
1da177e4 LT |
677 | } |
678 | goto out; | |
679 | ||
680 | confused: | |
681 | if (bio) | |
5948edbc | 682 | bio = mpage_bio_submit(wr, bio); |
1da177e4 | 683 | |
0ea97180 MS |
684 | if (mpd->use_writepage) { |
685 | ret = mapping->a_ops->writepage(page, wbc); | |
1da177e4 | 686 | } else { |
0ea97180 | 687 | ret = -EAGAIN; |
1da177e4 LT |
688 | goto out; |
689 | } | |
690 | /* | |
691 | * The caller has a ref on the inode, so *mapping is stable | |
692 | */ | |
0ea97180 | 693 | mapping_set_error(mapping, ret); |
1da177e4 | 694 | out: |
0ea97180 MS |
695 | mpd->bio = bio; |
696 | return ret; | |
1da177e4 LT |
697 | } |
698 | ||
699 | /** | |
78a4a50a | 700 | * mpage_writepages - walk the list of dirty pages of the given address space & writepage() all of them |
1da177e4 LT |
701 | * @mapping: address space structure to write |
702 | * @wbc: subtract the number of written pages from *@wbc->nr_to_write | |
703 | * @get_block: the filesystem's block mapper function. | |
704 | * If this is NULL then use a_ops->writepage. Otherwise, go | |
705 | * direct-to-BIO. | |
706 | * | |
707 | * This is a library function, which implements the writepages() | |
708 | * address_space_operation. | |
709 | * | |
710 | * If a page is already under I/O, generic_writepages() skips it, even | |
711 | * if it's dirty. This is desirable behaviour for memory-cleaning writeback, | |
712 | * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() | |
713 | * and msync() need to guarantee that all the data which was dirty at the time | |
714 | * the call was made get new I/O started against them. If wbc->sync_mode is | |
715 | * WB_SYNC_ALL then we were called for data integrity and we must wait for | |
716 | * existing IO to complete. | |
717 | */ | |
718 | int | |
719 | mpage_writepages(struct address_space *mapping, | |
720 | struct writeback_control *wbc, get_block_t get_block) | |
1da177e4 | 721 | { |
2ed1a6bc | 722 | struct blk_plug plug; |
0ea97180 MS |
723 | int ret; |
724 | ||
2ed1a6bc JA |
725 | blk_start_plug(&plug); |
726 | ||
0ea97180 MS |
727 | if (!get_block) |
728 | ret = generic_writepages(mapping, wbc); | |
729 | else { | |
730 | struct mpage_data mpd = { | |
731 | .bio = NULL, | |
732 | .last_block_in_bio = 0, | |
733 | .get_block = get_block, | |
734 | .use_writepage = 1, | |
735 | }; | |
736 | ||
737 | ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd); | |
5948edbc RP |
738 | if (mpd.bio) { |
739 | int wr = (wbc->sync_mode == WB_SYNC_ALL ? | |
740 | WRITE_SYNC : WRITE); | |
741 | mpage_bio_submit(wr, mpd.bio); | |
742 | } | |
1da177e4 | 743 | } |
2ed1a6bc | 744 | blk_finish_plug(&plug); |
1da177e4 LT |
745 | return ret; |
746 | } | |
747 | EXPORT_SYMBOL(mpage_writepages); | |
1da177e4 LT |
748 | |
749 | int mpage_writepage(struct page *page, get_block_t get_block, | |
750 | struct writeback_control *wbc) | |
751 | { | |
0ea97180 MS |
752 | struct mpage_data mpd = { |
753 | .bio = NULL, | |
754 | .last_block_in_bio = 0, | |
755 | .get_block = get_block, | |
756 | .use_writepage = 0, | |
757 | }; | |
758 | int ret = __mpage_writepage(page, wbc, &mpd); | |
5948edbc RP |
759 | if (mpd.bio) { |
760 | int wr = (wbc->sync_mode == WB_SYNC_ALL ? | |
761 | WRITE_SYNC : WRITE); | |
762 | mpage_bio_submit(wr, mpd.bio); | |
763 | } | |
1da177e4 LT |
764 | return ret; |
765 | } | |
766 | EXPORT_SYMBOL(mpage_writepage); |