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0bd49f94 RK |
1 | /* |
2 | * page.c - buffer/page management specific to NILFS | |
3 | * | |
4 | * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
4b420ab4 | 16 | * Written by Ryusuke Konishi and Seiji Kihara. |
0bd49f94 RK |
17 | */ |
18 | ||
19 | #include <linux/pagemap.h> | |
20 | #include <linux/writeback.h> | |
21 | #include <linux/swap.h> | |
22 | #include <linux/bitops.h> | |
23 | #include <linux/page-flags.h> | |
24 | #include <linux/list.h> | |
25 | #include <linux/highmem.h> | |
26 | #include <linux/pagevec.h> | |
5a0e3ad6 | 27 | #include <linux/gfp.h> |
0bd49f94 RK |
28 | #include "nilfs.h" |
29 | #include "page.h" | |
30 | #include "mdt.h" | |
31 | ||
32 | ||
4ce5c342 RK |
33 | #define NILFS_BUFFER_INHERENT_BITS \ |
34 | (BIT(BH_Uptodate) | BIT(BH_Mapped) | BIT(BH_NILFS_Node) | \ | |
35 | BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Checked)) | |
0bd49f94 RK |
36 | |
37 | static struct buffer_head * | |
38 | __nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index, | |
39 | int blkbits, unsigned long b_state) | |
40 | ||
41 | { | |
42 | unsigned long first_block; | |
43 | struct buffer_head *bh; | |
44 | ||
45 | if (!page_has_buffers(page)) | |
46 | create_empty_buffers(page, 1 << blkbits, b_state); | |
47 | ||
09cbfeaf | 48 | first_block = (unsigned long)index << (PAGE_SHIFT - blkbits); |
0bd49f94 RK |
49 | bh = nilfs_page_get_nth_block(page, block - first_block); |
50 | ||
51 | touch_buffer(bh); | |
52 | wait_on_buffer(bh); | |
53 | return bh; | |
54 | } | |
55 | ||
0bd49f94 RK |
56 | struct buffer_head *nilfs_grab_buffer(struct inode *inode, |
57 | struct address_space *mapping, | |
58 | unsigned long blkoff, | |
59 | unsigned long b_state) | |
60 | { | |
61 | int blkbits = inode->i_blkbits; | |
09cbfeaf | 62 | pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits); |
c1c1d709 RK |
63 | struct page *page; |
64 | struct buffer_head *bh; | |
0bd49f94 RK |
65 | |
66 | page = grab_cache_page(mapping, index); | |
67 | if (unlikely(!page)) | |
68 | return NULL; | |
69 | ||
70 | bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state); | |
71 | if (unlikely(!bh)) { | |
72 | unlock_page(page); | |
09cbfeaf | 73 | put_page(page); |
0bd49f94 RK |
74 | return NULL; |
75 | } | |
0bd49f94 RK |
76 | return bh; |
77 | } | |
78 | ||
79 | /** | |
80 | * nilfs_forget_buffer - discard dirty state | |
81 | * @inode: owner inode of the buffer | |
82 | * @bh: buffer head of the buffer to be discarded | |
83 | */ | |
84 | void nilfs_forget_buffer(struct buffer_head *bh) | |
85 | { | |
86 | struct page *page = bh->b_page; | |
ead8ecff | 87 | const unsigned long clear_bits = |
4ce5c342 RK |
88 | (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) | |
89 | BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) | | |
90 | BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected)); | |
0bd49f94 RK |
91 | |
92 | lock_buffer(bh); | |
ead8ecff | 93 | set_mask_bits(&bh->b_state, clear_bits, 0); |
84338237 | 94 | if (nilfs_page_buffers_clean(page)) |
0bd49f94 RK |
95 | __nilfs_clear_page_dirty(page); |
96 | ||
0bd49f94 RK |
97 | bh->b_blocknr = -1; |
98 | ClearPageUptodate(page); | |
99 | ClearPageMappedToDisk(page); | |
100 | unlock_buffer(bh); | |
101 | brelse(bh); | |
102 | } | |
103 | ||
104 | /** | |
105 | * nilfs_copy_buffer -- copy buffer data and flags | |
106 | * @dbh: destination buffer | |
107 | * @sbh: source buffer | |
108 | */ | |
109 | void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh) | |
110 | { | |
111 | void *kaddr0, *kaddr1; | |
112 | unsigned long bits; | |
113 | struct page *spage = sbh->b_page, *dpage = dbh->b_page; | |
114 | struct buffer_head *bh; | |
115 | ||
7b9c0976 CW |
116 | kaddr0 = kmap_atomic(spage); |
117 | kaddr1 = kmap_atomic(dpage); | |
0bd49f94 | 118 | memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size); |
7b9c0976 CW |
119 | kunmap_atomic(kaddr1); |
120 | kunmap_atomic(kaddr0); | |
0bd49f94 RK |
121 | |
122 | dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS; | |
123 | dbh->b_blocknr = sbh->b_blocknr; | |
124 | dbh->b_bdev = sbh->b_bdev; | |
125 | ||
126 | bh = dbh; | |
4ce5c342 | 127 | bits = sbh->b_state & (BIT(BH_Uptodate) | BIT(BH_Mapped)); |
0bd49f94 RK |
128 | while ((bh = bh->b_this_page) != dbh) { |
129 | lock_buffer(bh); | |
130 | bits &= bh->b_state; | |
131 | unlock_buffer(bh); | |
132 | } | |
4ce5c342 | 133 | if (bits & BIT(BH_Uptodate)) |
0bd49f94 RK |
134 | SetPageUptodate(dpage); |
135 | else | |
136 | ClearPageUptodate(dpage); | |
4ce5c342 | 137 | if (bits & BIT(BH_Mapped)) |
0bd49f94 RK |
138 | SetPageMappedToDisk(dpage); |
139 | else | |
140 | ClearPageMappedToDisk(dpage); | |
141 | } | |
142 | ||
143 | /** | |
144 | * nilfs_page_buffers_clean - check if a page has dirty buffers or not. | |
145 | * @page: page to be checked | |
146 | * | |
147 | * nilfs_page_buffers_clean() returns zero if the page has dirty buffers. | |
148 | * Otherwise, it returns non-zero value. | |
149 | */ | |
150 | int nilfs_page_buffers_clean(struct page *page) | |
151 | { | |
152 | struct buffer_head *bh, *head; | |
153 | ||
154 | bh = head = page_buffers(page); | |
155 | do { | |
156 | if (buffer_dirty(bh)) | |
157 | return 0; | |
158 | bh = bh->b_this_page; | |
159 | } while (bh != head); | |
160 | return 1; | |
161 | } | |
162 | ||
163 | void nilfs_page_bug(struct page *page) | |
164 | { | |
165 | struct address_space *m; | |
aa405b1f | 166 | unsigned long ino; |
0bd49f94 RK |
167 | |
168 | if (unlikely(!page)) { | |
169 | printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n"); | |
170 | return; | |
171 | } | |
172 | ||
173 | m = page->mapping; | |
aa405b1f RK |
174 | ino = m ? m->host->i_ino : 0; |
175 | ||
0bd49f94 RK |
176 | printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx " |
177 | "mapping=%p ino=%lu\n", | |
fe896d18 | 178 | page, page_ref_count(page), |
0bd49f94 RK |
179 | (unsigned long long)page->index, page->flags, m, ino); |
180 | ||
181 | if (page_has_buffers(page)) { | |
182 | struct buffer_head *bh, *head; | |
183 | int i = 0; | |
184 | ||
185 | bh = head = page_buffers(page); | |
186 | do { | |
187 | printk(KERN_CRIT | |
188 | " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n", | |
189 | i++, bh, atomic_read(&bh->b_count), | |
190 | (unsigned long long)bh->b_blocknr, bh->b_state); | |
191 | bh = bh->b_this_page; | |
192 | } while (bh != head); | |
193 | } | |
194 | } | |
195 | ||
0bd49f94 RK |
196 | /** |
197 | * nilfs_copy_page -- copy the page with buffers | |
198 | * @dst: destination page | |
199 | * @src: source page | |
200 | * @copy_dirty: flag whether to copy dirty states on the page's buffer heads. | |
201 | * | |
7a65004b | 202 | * This function is for both data pages and btnode pages. The dirty flag |
0bd49f94 RK |
203 | * should be treated by caller. The page must not be under i/o. |
204 | * Both src and dst page must be locked | |
205 | */ | |
206 | static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty) | |
207 | { | |
208 | struct buffer_head *dbh, *dbufs, *sbh, *sbufs; | |
209 | unsigned long mask = NILFS_BUFFER_INHERENT_BITS; | |
210 | ||
211 | BUG_ON(PageWriteback(dst)); | |
212 | ||
213 | sbh = sbufs = page_buffers(src); | |
214 | if (!page_has_buffers(dst)) | |
215 | create_empty_buffers(dst, sbh->b_size, 0); | |
216 | ||
217 | if (copy_dirty) | |
4ce5c342 | 218 | mask |= BIT(BH_Dirty); |
0bd49f94 RK |
219 | |
220 | dbh = dbufs = page_buffers(dst); | |
221 | do { | |
222 | lock_buffer(sbh); | |
223 | lock_buffer(dbh); | |
224 | dbh->b_state = sbh->b_state & mask; | |
225 | dbh->b_blocknr = sbh->b_blocknr; | |
226 | dbh->b_bdev = sbh->b_bdev; | |
227 | sbh = sbh->b_this_page; | |
228 | dbh = dbh->b_this_page; | |
229 | } while (dbh != dbufs); | |
230 | ||
231 | copy_highpage(dst, src); | |
232 | ||
233 | if (PageUptodate(src) && !PageUptodate(dst)) | |
234 | SetPageUptodate(dst); | |
235 | else if (!PageUptodate(src) && PageUptodate(dst)) | |
236 | ClearPageUptodate(dst); | |
237 | if (PageMappedToDisk(src) && !PageMappedToDisk(dst)) | |
238 | SetPageMappedToDisk(dst); | |
239 | else if (!PageMappedToDisk(src) && PageMappedToDisk(dst)) | |
240 | ClearPageMappedToDisk(dst); | |
241 | ||
242 | do { | |
243 | unlock_buffer(sbh); | |
244 | unlock_buffer(dbh); | |
245 | sbh = sbh->b_this_page; | |
246 | dbh = dbh->b_this_page; | |
247 | } while (dbh != dbufs); | |
248 | } | |
249 | ||
250 | int nilfs_copy_dirty_pages(struct address_space *dmap, | |
251 | struct address_space *smap) | |
252 | { | |
253 | struct pagevec pvec; | |
254 | unsigned int i; | |
255 | pgoff_t index = 0; | |
256 | int err = 0; | |
257 | ||
86679820 | 258 | pagevec_init(&pvec); |
0bd49f94 | 259 | repeat: |
67fd707f | 260 | if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY)) |
0bd49f94 RK |
261 | return 0; |
262 | ||
263 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
264 | struct page *page = pvec.pages[i], *dpage; | |
265 | ||
266 | lock_page(page); | |
267 | if (unlikely(!PageDirty(page))) | |
268 | NILFS_PAGE_BUG(page, "inconsistent dirty state"); | |
269 | ||
270 | dpage = grab_cache_page(dmap, page->index); | |
271 | if (unlikely(!dpage)) { | |
272 | /* No empty page is added to the page cache */ | |
273 | err = -ENOMEM; | |
274 | unlock_page(page); | |
275 | break; | |
276 | } | |
277 | if (unlikely(!page_has_buffers(page))) | |
278 | NILFS_PAGE_BUG(page, | |
279 | "found empty page in dat page cache"); | |
280 | ||
281 | nilfs_copy_page(dpage, page, 1); | |
282 | __set_page_dirty_nobuffers(dpage); | |
283 | ||
284 | unlock_page(dpage); | |
09cbfeaf | 285 | put_page(dpage); |
0bd49f94 RK |
286 | unlock_page(page); |
287 | } | |
288 | pagevec_release(&pvec); | |
289 | cond_resched(); | |
290 | ||
291 | if (likely(!err)) | |
292 | goto repeat; | |
293 | return err; | |
294 | } | |
295 | ||
296 | /** | |
7a65004b | 297 | * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache |
0bd49f94 RK |
298 | * @dmap: destination page cache |
299 | * @smap: source page cache | |
300 | * | |
301 | * No pages must no be added to the cache during this process. | |
302 | * This must be ensured by the caller. | |
303 | */ | |
304 | void nilfs_copy_back_pages(struct address_space *dmap, | |
305 | struct address_space *smap) | |
306 | { | |
307 | struct pagevec pvec; | |
308 | unsigned int i, n; | |
309 | pgoff_t index = 0; | |
310 | int err; | |
311 | ||
86679820 | 312 | pagevec_init(&pvec); |
0bd49f94 | 313 | repeat: |
397162ff | 314 | n = pagevec_lookup(&pvec, smap, &index); |
0bd49f94 RK |
315 | if (!n) |
316 | return; | |
0bd49f94 RK |
317 | |
318 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
319 | struct page *page = pvec.pages[i], *dpage; | |
320 | pgoff_t offset = page->index; | |
321 | ||
322 | lock_page(page); | |
323 | dpage = find_lock_page(dmap, offset); | |
324 | if (dpage) { | |
325 | /* override existing page on the destination cache */ | |
1f5abe7e | 326 | WARN_ON(PageDirty(dpage)); |
0bd49f94 RK |
327 | nilfs_copy_page(dpage, page, 0); |
328 | unlock_page(dpage); | |
09cbfeaf | 329 | put_page(dpage); |
0bd49f94 RK |
330 | } else { |
331 | struct page *page2; | |
332 | ||
333 | /* move the page to the destination cache */ | |
334 | spin_lock_irq(&smap->tree_lock); | |
335 | page2 = radix_tree_delete(&smap->page_tree, offset); | |
1f5abe7e RK |
336 | WARN_ON(page2 != page); |
337 | ||
0bd49f94 RK |
338 | smap->nrpages--; |
339 | spin_unlock_irq(&smap->tree_lock); | |
340 | ||
341 | spin_lock_irq(&dmap->tree_lock); | |
342 | err = radix_tree_insert(&dmap->page_tree, offset, page); | |
343 | if (unlikely(err < 0)) { | |
1f5abe7e | 344 | WARN_ON(err == -EEXIST); |
0bd49f94 | 345 | page->mapping = NULL; |
09cbfeaf | 346 | put_page(page); /* for cache */ |
0bd49f94 RK |
347 | } else { |
348 | page->mapping = dmap; | |
349 | dmap->nrpages++; | |
350 | if (PageDirty(page)) | |
351 | radix_tree_tag_set(&dmap->page_tree, | |
352 | offset, | |
353 | PAGECACHE_TAG_DIRTY); | |
354 | } | |
355 | spin_unlock_irq(&dmap->tree_lock); | |
356 | } | |
357 | unlock_page(page); | |
358 | } | |
359 | pagevec_release(&pvec); | |
360 | cond_resched(); | |
361 | ||
362 | goto repeat; | |
363 | } | |
364 | ||
8c26c4e2 VD |
365 | /** |
366 | * nilfs_clear_dirty_pages - discard dirty pages in address space | |
367 | * @mapping: address space with dirty pages for discarding | |
368 | * @silent: suppress [true] or print [false] warning messages | |
369 | */ | |
370 | void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent) | |
0bd49f94 RK |
371 | { |
372 | struct pagevec pvec; | |
373 | unsigned int i; | |
374 | pgoff_t index = 0; | |
375 | ||
86679820 | 376 | pagevec_init(&pvec); |
0bd49f94 | 377 | |
67fd707f JK |
378 | while (pagevec_lookup_tag(&pvec, mapping, &index, |
379 | PAGECACHE_TAG_DIRTY)) { | |
0bd49f94 RK |
380 | for (i = 0; i < pagevec_count(&pvec); i++) { |
381 | struct page *page = pvec.pages[i]; | |
0bd49f94 RK |
382 | |
383 | lock_page(page); | |
8c26c4e2 | 384 | nilfs_clear_dirty_page(page, silent); |
0bd49f94 RK |
385 | unlock_page(page); |
386 | } | |
387 | pagevec_release(&pvec); | |
388 | cond_resched(); | |
389 | } | |
390 | } | |
391 | ||
8c26c4e2 VD |
392 | /** |
393 | * nilfs_clear_dirty_page - discard dirty page | |
394 | * @page: dirty page that will be discarded | |
395 | * @silent: suppress [true] or print [false] warning messages | |
396 | */ | |
397 | void nilfs_clear_dirty_page(struct page *page, bool silent) | |
398 | { | |
399 | struct inode *inode = page->mapping->host; | |
400 | struct super_block *sb = inode->i_sb; | |
401 | ||
dc33f5f3 | 402 | BUG_ON(!PageLocked(page)); |
8c26c4e2 | 403 | |
d6517deb RK |
404 | if (!silent) |
405 | nilfs_msg(sb, KERN_WARNING, | |
406 | "discard dirty page: offset=%lld, ino=%lu", | |
407 | page_offset(page), inode->i_ino); | |
8c26c4e2 VD |
408 | |
409 | ClearPageUptodate(page); | |
410 | ClearPageMappedToDisk(page); | |
411 | ||
412 | if (page_has_buffers(page)) { | |
413 | struct buffer_head *bh, *head; | |
ead8ecff | 414 | const unsigned long clear_bits = |
4ce5c342 RK |
415 | (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) | |
416 | BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) | | |
417 | BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected)); | |
8c26c4e2 VD |
418 | |
419 | bh = head = page_buffers(page); | |
420 | do { | |
421 | lock_buffer(bh); | |
d6517deb RK |
422 | if (!silent) |
423 | nilfs_msg(sb, KERN_WARNING, | |
424 | "discard dirty block: blocknr=%llu, size=%zu", | |
425 | (u64)bh->b_blocknr, bh->b_size); | |
426 | ||
ead8ecff | 427 | set_mask_bits(&bh->b_state, clear_bits, 0); |
8c26c4e2 VD |
428 | unlock_buffer(bh); |
429 | } while (bh = bh->b_this_page, bh != head); | |
430 | } | |
431 | ||
432 | __nilfs_clear_page_dirty(page); | |
433 | } | |
434 | ||
0c6c44cb RK |
435 | unsigned int nilfs_page_count_clean_buffers(struct page *page, |
436 | unsigned int from, unsigned int to) | |
0bd49f94 | 437 | { |
0c6c44cb | 438 | unsigned int block_start, block_end; |
0bd49f94 | 439 | struct buffer_head *bh, *head; |
0c6c44cb | 440 | unsigned int nc = 0; |
0bd49f94 RK |
441 | |
442 | for (bh = head = page_buffers(page), block_start = 0; | |
443 | bh != head || !block_start; | |
444 | block_start = block_end, bh = bh->b_this_page) { | |
445 | block_end = block_start + bh->b_size; | |
446 | if (block_end > from && block_start < to && !buffer_dirty(bh)) | |
447 | nc++; | |
448 | } | |
449 | return nc; | |
450 | } | |
ae53a0a2 | 451 | |
b83ae6d4 | 452 | void nilfs_mapping_init(struct address_space *mapping, struct inode *inode) |
ebdfed4d | 453 | { |
aa405b1f | 454 | mapping->host = inode; |
ebdfed4d RK |
455 | mapping->flags = 0; |
456 | mapping_set_gfp_mask(mapping, GFP_NOFS); | |
252aa6f5 | 457 | mapping->private_data = NULL; |
d611b22f | 458 | mapping->a_ops = &empty_aops; |
ebdfed4d | 459 | } |
0bd49f94 RK |
460 | |
461 | /* | |
462 | * NILFS2 needs clear_page_dirty() in the following two cases: | |
463 | * | |
464 | * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears | |
465 | * page dirty flags when it copies back pages from the shadow cache | |
466 | * (gcdat->{i_mapping,i_btnode_cache}) to its original cache | |
467 | * (dat->{i_mapping,i_btnode_cache}). | |
468 | * | |
469 | * 2) Some B-tree operations like insertion or deletion may dispose buffers | |
470 | * in dirty state, and this needs to cancel the dirty state of their pages. | |
471 | */ | |
472 | int __nilfs_clear_page_dirty(struct page *page) | |
473 | { | |
474 | struct address_space *mapping = page->mapping; | |
475 | ||
476 | if (mapping) { | |
477 | spin_lock_irq(&mapping->tree_lock); | |
478 | if (test_bit(PG_dirty, &page->flags)) { | |
479 | radix_tree_tag_clear(&mapping->page_tree, | |
480 | page_index(page), | |
481 | PAGECACHE_TAG_DIRTY); | |
482 | spin_unlock_irq(&mapping->tree_lock); | |
483 | return clear_page_dirty_for_io(page); | |
484 | } | |
485 | spin_unlock_irq(&mapping->tree_lock); | |
486 | return 0; | |
487 | } | |
488 | return TestClearPageDirty(page); | |
489 | } | |
622daaff RK |
490 | |
491 | /** | |
492 | * nilfs_find_uncommitted_extent - find extent of uncommitted data | |
493 | * @inode: inode | |
494 | * @start_blk: start block offset (in) | |
495 | * @blkoff: start offset of the found extent (out) | |
496 | * | |
497 | * This function searches an extent of buffers marked "delayed" which | |
498 | * starts from a block offset equal to or larger than @start_blk. If | |
499 | * such an extent was found, this will store the start offset in | |
500 | * @blkoff and return its length in blocks. Otherwise, zero is | |
501 | * returned. | |
502 | */ | |
503 | unsigned long nilfs_find_uncommitted_extent(struct inode *inode, | |
504 | sector_t start_blk, | |
505 | sector_t *blkoff) | |
506 | { | |
507 | unsigned int i; | |
508 | pgoff_t index; | |
509 | unsigned int nblocks_in_page; | |
510 | unsigned long length = 0; | |
511 | sector_t b; | |
512 | struct pagevec pvec; | |
513 | struct page *page; | |
514 | ||
515 | if (inode->i_mapping->nrpages == 0) | |
516 | return 0; | |
517 | ||
09cbfeaf KS |
518 | index = start_blk >> (PAGE_SHIFT - inode->i_blkbits); |
519 | nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits); | |
622daaff | 520 | |
86679820 | 521 | pagevec_init(&pvec); |
622daaff RK |
522 | |
523 | repeat: | |
524 | pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE, | |
525 | pvec.pages); | |
526 | if (pvec.nr == 0) | |
527 | return length; | |
528 | ||
529 | if (length > 0 && pvec.pages[0]->index > index) | |
530 | goto out; | |
531 | ||
09cbfeaf | 532 | b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits); |
622daaff RK |
533 | i = 0; |
534 | do { | |
535 | page = pvec.pages[i]; | |
536 | ||
537 | lock_page(page); | |
538 | if (page_has_buffers(page)) { | |
539 | struct buffer_head *bh, *head; | |
540 | ||
541 | bh = head = page_buffers(page); | |
542 | do { | |
543 | if (b < start_blk) | |
544 | continue; | |
545 | if (buffer_delay(bh)) { | |
546 | if (length == 0) | |
547 | *blkoff = b; | |
548 | length++; | |
549 | } else if (length > 0) { | |
550 | goto out_locked; | |
551 | } | |
552 | } while (++b, bh = bh->b_this_page, bh != head); | |
553 | } else { | |
554 | if (length > 0) | |
555 | goto out_locked; | |
556 | ||
557 | b += nblocks_in_page; | |
558 | } | |
559 | unlock_page(page); | |
560 | ||
561 | } while (++i < pagevec_count(&pvec)); | |
562 | ||
563 | index = page->index + 1; | |
564 | pagevec_release(&pvec); | |
565 | cond_resched(); | |
566 | goto repeat; | |
567 | ||
568 | out_locked: | |
569 | unlock_page(page); | |
570 | out: | |
571 | pagevec_release(&pvec); | |
572 | return length; | |
573 | } |