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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 *
16 * Written by Ryusuke Konishi and Seiji Kihara.
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>
27 #include <linux/gfp.h>
28 #include "nilfs.h"
29 #include "page.h"
30 #include "mdt.h"
31
32
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))
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
48 first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
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
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;
62 pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
63 struct page *page;
64 struct buffer_head *bh;
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);
73 put_page(page);
74 return NULL;
75 }
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;
87 const unsigned long clear_bits =
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));
91
92 lock_buffer(bh);
93 set_mask_bits(&bh->b_state, clear_bits, 0);
94 if (nilfs_page_buffers_clean(page))
95 __nilfs_clear_page_dirty(page);
96
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
116 kaddr0 = kmap_atomic(spage);
117 kaddr1 = kmap_atomic(dpage);
118 memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
119 kunmap_atomic(kaddr1);
120 kunmap_atomic(kaddr0);
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;
127 bits = sbh->b_state & (BIT(BH_Uptodate) | BIT(BH_Mapped));
128 while ((bh = bh->b_this_page) != dbh) {
129 lock_buffer(bh);
130 bits &= bh->b_state;
131 unlock_buffer(bh);
132 }
133 if (bits & BIT(BH_Uptodate))
134 SetPageUptodate(dpage);
135 else
136 ClearPageUptodate(dpage);
137 if (bits & BIT(BH_Mapped))
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;
166 unsigned long ino;
167
168 if (unlikely(!page)) {
169 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
170 return;
171 }
172
173 m = page->mapping;
174 ino = m ? m->host->i_ino : 0;
175
176 printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
177 "mapping=%p ino=%lu\n",
178 page, page_ref_count(page),
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
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 *
202 * This function is for both data pages and btnode pages. The dirty flag
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)
218 mask |= BIT(BH_Dirty);
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
258 pagevec_init(&pvec, 0);
259 repeat:
260 if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
261 PAGEVEC_SIZE))
262 return 0;
263
264 for (i = 0; i < pagevec_count(&pvec); i++) {
265 struct page *page = pvec.pages[i], *dpage;
266
267 lock_page(page);
268 if (unlikely(!PageDirty(page)))
269 NILFS_PAGE_BUG(page, "inconsistent dirty state");
270
271 dpage = grab_cache_page(dmap, page->index);
272 if (unlikely(!dpage)) {
273 /* No empty page is added to the page cache */
274 err = -ENOMEM;
275 unlock_page(page);
276 break;
277 }
278 if (unlikely(!page_has_buffers(page)))
279 NILFS_PAGE_BUG(page,
280 "found empty page in dat page cache");
281
282 nilfs_copy_page(dpage, page, 1);
283 __set_page_dirty_nobuffers(dpage);
284
285 unlock_page(dpage);
286 put_page(dpage);
287 unlock_page(page);
288 }
289 pagevec_release(&pvec);
290 cond_resched();
291
292 if (likely(!err))
293 goto repeat;
294 return err;
295 }
296
297 /**
298 * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
299 * @dmap: destination page cache
300 * @smap: source page cache
301 *
302 * No pages must no be added to the cache during this process.
303 * This must be ensured by the caller.
304 */
305 void nilfs_copy_back_pages(struct address_space *dmap,
306 struct address_space *smap)
307 {
308 struct pagevec pvec;
309 unsigned int i, n;
310 pgoff_t index = 0;
311 int err;
312
313 pagevec_init(&pvec, 0);
314 repeat:
315 n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
316 if (!n)
317 return;
318 index = pvec.pages[n - 1]->index + 1;
319
320 for (i = 0; i < pagevec_count(&pvec); i++) {
321 struct page *page = pvec.pages[i], *dpage;
322 pgoff_t offset = page->index;
323
324 lock_page(page);
325 dpage = find_lock_page(dmap, offset);
326 if (dpage) {
327 /* override existing page on the destination cache */
328 WARN_ON(PageDirty(dpage));
329 nilfs_copy_page(dpage, page, 0);
330 unlock_page(dpage);
331 put_page(dpage);
332 } else {
333 struct page *page2;
334
335 /* move the page to the destination cache */
336 spin_lock_irq(&smap->tree_lock);
337 page2 = radix_tree_delete(&smap->page_tree, offset);
338 WARN_ON(page2 != page);
339
340 smap->nrpages--;
341 spin_unlock_irq(&smap->tree_lock);
342
343 spin_lock_irq(&dmap->tree_lock);
344 err = radix_tree_insert(&dmap->page_tree, offset, page);
345 if (unlikely(err < 0)) {
346 WARN_ON(err == -EEXIST);
347 page->mapping = NULL;
348 put_page(page); /* for cache */
349 } else {
350 page->mapping = dmap;
351 dmap->nrpages++;
352 if (PageDirty(page))
353 radix_tree_tag_set(&dmap->page_tree,
354 offset,
355 PAGECACHE_TAG_DIRTY);
356 }
357 spin_unlock_irq(&dmap->tree_lock);
358 }
359 unlock_page(page);
360 }
361 pagevec_release(&pvec);
362 cond_resched();
363
364 goto repeat;
365 }
366
367 /**
368 * nilfs_clear_dirty_pages - discard dirty pages in address space
369 * @mapping: address space with dirty pages for discarding
370 * @silent: suppress [true] or print [false] warning messages
371 */
372 void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
373 {
374 struct pagevec pvec;
375 unsigned int i;
376 pgoff_t index = 0;
377
378 pagevec_init(&pvec, 0);
379
380 while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
381 PAGEVEC_SIZE)) {
382 for (i = 0; i < pagevec_count(&pvec); i++) {
383 struct page *page = pvec.pages[i];
384
385 lock_page(page);
386 nilfs_clear_dirty_page(page, silent);
387 unlock_page(page);
388 }
389 pagevec_release(&pvec);
390 cond_resched();
391 }
392 }
393
394 /**
395 * nilfs_clear_dirty_page - discard dirty page
396 * @page: dirty page that will be discarded
397 * @silent: suppress [true] or print [false] warning messages
398 */
399 void nilfs_clear_dirty_page(struct page *page, bool silent)
400 {
401 struct inode *inode = page->mapping->host;
402 struct super_block *sb = inode->i_sb;
403
404 BUG_ON(!PageLocked(page));
405
406 if (!silent)
407 nilfs_msg(sb, KERN_WARNING,
408 "discard dirty page: offset=%lld, ino=%lu",
409 page_offset(page), inode->i_ino);
410
411 ClearPageUptodate(page);
412 ClearPageMappedToDisk(page);
413
414 if (page_has_buffers(page)) {
415 struct buffer_head *bh, *head;
416 const unsigned long clear_bits =
417 (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
418 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
419 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
420
421 bh = head = page_buffers(page);
422 do {
423 lock_buffer(bh);
424 if (!silent)
425 nilfs_msg(sb, KERN_WARNING,
426 "discard dirty block: blocknr=%llu, size=%zu",
427 (u64)bh->b_blocknr, bh->b_size);
428
429 set_mask_bits(&bh->b_state, clear_bits, 0);
430 unlock_buffer(bh);
431 } while (bh = bh->b_this_page, bh != head);
432 }
433
434 __nilfs_clear_page_dirty(page);
435 }
436
437 unsigned int nilfs_page_count_clean_buffers(struct page *page,
438 unsigned int from, unsigned int to)
439 {
440 unsigned int block_start, block_end;
441 struct buffer_head *bh, *head;
442 unsigned int nc = 0;
443
444 for (bh = head = page_buffers(page), block_start = 0;
445 bh != head || !block_start;
446 block_start = block_end, bh = bh->b_this_page) {
447 block_end = block_start + bh->b_size;
448 if (block_end > from && block_start < to && !buffer_dirty(bh))
449 nc++;
450 }
451 return nc;
452 }
453
454 void nilfs_mapping_init(struct address_space *mapping, struct inode *inode)
455 {
456 mapping->host = inode;
457 mapping->flags = 0;
458 mapping_set_gfp_mask(mapping, GFP_NOFS);
459 mapping->private_data = NULL;
460 mapping->a_ops = &empty_aops;
461 }
462
463 /*
464 * NILFS2 needs clear_page_dirty() in the following two cases:
465 *
466 * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
467 * page dirty flags when it copies back pages from the shadow cache
468 * (gcdat->{i_mapping,i_btnode_cache}) to its original cache
469 * (dat->{i_mapping,i_btnode_cache}).
470 *
471 * 2) Some B-tree operations like insertion or deletion may dispose buffers
472 * in dirty state, and this needs to cancel the dirty state of their pages.
473 */
474 int __nilfs_clear_page_dirty(struct page *page)
475 {
476 struct address_space *mapping = page->mapping;
477
478 if (mapping) {
479 spin_lock_irq(&mapping->tree_lock);
480 if (test_bit(PG_dirty, &page->flags)) {
481 radix_tree_tag_clear(&mapping->page_tree,
482 page_index(page),
483 PAGECACHE_TAG_DIRTY);
484 spin_unlock_irq(&mapping->tree_lock);
485 return clear_page_dirty_for_io(page);
486 }
487 spin_unlock_irq(&mapping->tree_lock);
488 return 0;
489 }
490 return TestClearPageDirty(page);
491 }
492
493 /**
494 * nilfs_find_uncommitted_extent - find extent of uncommitted data
495 * @inode: inode
496 * @start_blk: start block offset (in)
497 * @blkoff: start offset of the found extent (out)
498 *
499 * This function searches an extent of buffers marked "delayed" which
500 * starts from a block offset equal to or larger than @start_blk. If
501 * such an extent was found, this will store the start offset in
502 * @blkoff and return its length in blocks. Otherwise, zero is
503 * returned.
504 */
505 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
506 sector_t start_blk,
507 sector_t *blkoff)
508 {
509 unsigned int i;
510 pgoff_t index;
511 unsigned int nblocks_in_page;
512 unsigned long length = 0;
513 sector_t b;
514 struct pagevec pvec;
515 struct page *page;
516
517 if (inode->i_mapping->nrpages == 0)
518 return 0;
519
520 index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
521 nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits);
522
523 pagevec_init(&pvec, 0);
524
525 repeat:
526 pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
527 pvec.pages);
528 if (pvec.nr == 0)
529 return length;
530
531 if (length > 0 && pvec.pages[0]->index > index)
532 goto out;
533
534 b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits);
535 i = 0;
536 do {
537 page = pvec.pages[i];
538
539 lock_page(page);
540 if (page_has_buffers(page)) {
541 struct buffer_head *bh, *head;
542
543 bh = head = page_buffers(page);
544 do {
545 if (b < start_blk)
546 continue;
547 if (buffer_delay(bh)) {
548 if (length == 0)
549 *blkoff = b;
550 length++;
551 } else if (length > 0) {
552 goto out_locked;
553 }
554 } while (++b, bh = bh->b_this_page, bh != head);
555 } else {
556 if (length > 0)
557 goto out_locked;
558
559 b += nblocks_in_page;
560 }
561 unlock_page(page);
562
563 } while (++i < pagevec_count(&pvec));
564
565 index = page->index + 1;
566 pagevec_release(&pvec);
567 cond_resched();
568 goto repeat;
569
570 out_locked:
571 unlock_page(page);
572 out:
573 pagevec_release(&pvec);
574 return length;
575 }