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 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 *
20 * Written by Ryusuke Konishi <ryusuke@osrg.net>,
21 * Seiji Kihara <kihara@osrg.net>.
22 */
23
24 #include <linux/pagemap.h>
25 #include <linux/writeback.h>
26 #include <linux/swap.h>
27 #include <linux/bitops.h>
28 #include <linux/page-flags.h>
29 #include <linux/list.h>
30 #include <linux/highmem.h>
31 #include <linux/pagevec.h>
32 #include <linux/gfp.h>
33 #include "nilfs.h"
34 #include "page.h"
35 #include "mdt.h"
36
37
38 #define NILFS_BUFFER_INHERENT_BITS \
39 ((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \
40 (1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Checked))
41
42 static struct buffer_head *
__nilfs_get_page_block(struct page * page,unsigned long block,pgoff_t index,int blkbits,unsigned long b_state)43 __nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
44 int blkbits, unsigned long b_state)
45
46 {
47 unsigned long first_block;
48 struct buffer_head *bh;
49
50 if (!page_has_buffers(page))
51 create_empty_buffers(page, 1 << blkbits, b_state);
52
53 first_block = (unsigned long)index << (PAGE_CACHE_SHIFT - blkbits);
54 bh = nilfs_page_get_nth_block(page, block - first_block);
55
56 touch_buffer(bh);
57 wait_on_buffer(bh);
58 return bh;
59 }
60
nilfs_grab_buffer(struct inode * inode,struct address_space * mapping,unsigned long blkoff,unsigned long b_state)61 struct buffer_head *nilfs_grab_buffer(struct inode *inode,
62 struct address_space *mapping,
63 unsigned long blkoff,
64 unsigned long b_state)
65 {
66 int blkbits = inode->i_blkbits;
67 pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
68 struct page *page;
69 struct buffer_head *bh;
70
71 page = grab_cache_page(mapping, index);
72 if (unlikely(!page))
73 return NULL;
74
75 bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
76 if (unlikely(!bh)) {
77 unlock_page(page);
78 page_cache_release(page);
79 return NULL;
80 }
81 return bh;
82 }
83
84 /**
85 * nilfs_forget_buffer - discard dirty state
86 * @inode: owner inode of the buffer
87 * @bh: buffer head of the buffer to be discarded
88 */
nilfs_forget_buffer(struct buffer_head * bh)89 void nilfs_forget_buffer(struct buffer_head *bh)
90 {
91 struct page *page = bh->b_page;
92 const unsigned long clear_bits =
93 (1 << BH_Uptodate | 1 << BH_Dirty | 1 << BH_Mapped |
94 1 << BH_Async_Write | 1 << BH_NILFS_Volatile |
95 1 << BH_NILFS_Checked | 1 << BH_NILFS_Redirected);
96
97 lock_buffer(bh);
98 set_mask_bits(&bh->b_state, clear_bits, 0);
99 if (nilfs_page_buffers_clean(page))
100 __nilfs_clear_page_dirty(page);
101
102 bh->b_blocknr = -1;
103 ClearPageUptodate(page);
104 ClearPageMappedToDisk(page);
105 unlock_buffer(bh);
106 brelse(bh);
107 }
108
109 /**
110 * nilfs_copy_buffer -- copy buffer data and flags
111 * @dbh: destination buffer
112 * @sbh: source buffer
113 */
nilfs_copy_buffer(struct buffer_head * dbh,struct buffer_head * sbh)114 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
115 {
116 void *kaddr0, *kaddr1;
117 unsigned long bits;
118 struct page *spage = sbh->b_page, *dpage = dbh->b_page;
119 struct buffer_head *bh;
120
121 kaddr0 = kmap_atomic(spage);
122 kaddr1 = kmap_atomic(dpage);
123 memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
124 kunmap_atomic(kaddr1);
125 kunmap_atomic(kaddr0);
126
127 dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
128 dbh->b_blocknr = sbh->b_blocknr;
129 dbh->b_bdev = sbh->b_bdev;
130
131 bh = dbh;
132 bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
133 while ((bh = bh->b_this_page) != dbh) {
134 lock_buffer(bh);
135 bits &= bh->b_state;
136 unlock_buffer(bh);
137 }
138 if (bits & (1UL << BH_Uptodate))
139 SetPageUptodate(dpage);
140 else
141 ClearPageUptodate(dpage);
142 if (bits & (1UL << BH_Mapped))
143 SetPageMappedToDisk(dpage);
144 else
145 ClearPageMappedToDisk(dpage);
146 }
147
148 /**
149 * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
150 * @page: page to be checked
151 *
152 * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
153 * Otherwise, it returns non-zero value.
154 */
nilfs_page_buffers_clean(struct page * page)155 int nilfs_page_buffers_clean(struct page *page)
156 {
157 struct buffer_head *bh, *head;
158
159 bh = head = page_buffers(page);
160 do {
161 if (buffer_dirty(bh))
162 return 0;
163 bh = bh->b_this_page;
164 } while (bh != head);
165 return 1;
166 }
167
nilfs_page_bug(struct page * page)168 void nilfs_page_bug(struct page *page)
169 {
170 struct address_space *m;
171 unsigned long ino;
172
173 if (unlikely(!page)) {
174 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
175 return;
176 }
177
178 m = page->mapping;
179 ino = m ? m->host->i_ino : 0;
180
181 printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
182 "mapping=%p ino=%lu\n",
183 page, atomic_read(&page->_count),
184 (unsigned long long)page->index, page->flags, m, ino);
185
186 if (page_has_buffers(page)) {
187 struct buffer_head *bh, *head;
188 int i = 0;
189
190 bh = head = page_buffers(page);
191 do {
192 printk(KERN_CRIT
193 " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
194 i++, bh, atomic_read(&bh->b_count),
195 (unsigned long long)bh->b_blocknr, bh->b_state);
196 bh = bh->b_this_page;
197 } while (bh != head);
198 }
199 }
200
201 /**
202 * nilfs_copy_page -- copy the page with buffers
203 * @dst: destination page
204 * @src: source page
205 * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
206 *
207 * This function is for both data pages and btnode pages. The dirty flag
208 * should be treated by caller. The page must not be under i/o.
209 * Both src and dst page must be locked
210 */
nilfs_copy_page(struct page * dst,struct page * src,int copy_dirty)211 static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
212 {
213 struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
214 unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
215
216 BUG_ON(PageWriteback(dst));
217
218 sbh = sbufs = page_buffers(src);
219 if (!page_has_buffers(dst))
220 create_empty_buffers(dst, sbh->b_size, 0);
221
222 if (copy_dirty)
223 mask |= (1UL << BH_Dirty);
224
225 dbh = dbufs = page_buffers(dst);
226 do {
227 lock_buffer(sbh);
228 lock_buffer(dbh);
229 dbh->b_state = sbh->b_state & mask;
230 dbh->b_blocknr = sbh->b_blocknr;
231 dbh->b_bdev = sbh->b_bdev;
232 sbh = sbh->b_this_page;
233 dbh = dbh->b_this_page;
234 } while (dbh != dbufs);
235
236 copy_highpage(dst, src);
237
238 if (PageUptodate(src) && !PageUptodate(dst))
239 SetPageUptodate(dst);
240 else if (!PageUptodate(src) && PageUptodate(dst))
241 ClearPageUptodate(dst);
242 if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
243 SetPageMappedToDisk(dst);
244 else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
245 ClearPageMappedToDisk(dst);
246
247 do {
248 unlock_buffer(sbh);
249 unlock_buffer(dbh);
250 sbh = sbh->b_this_page;
251 dbh = dbh->b_this_page;
252 } while (dbh != dbufs);
253 }
254
nilfs_copy_dirty_pages(struct address_space * dmap,struct address_space * smap)255 int nilfs_copy_dirty_pages(struct address_space *dmap,
256 struct address_space *smap)
257 {
258 struct pagevec pvec;
259 unsigned int i;
260 pgoff_t index = 0;
261 int err = 0;
262
263 pagevec_init(&pvec, 0);
264 repeat:
265 if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
266 PAGEVEC_SIZE))
267 return 0;
268
269 for (i = 0; i < pagevec_count(&pvec); i++) {
270 struct page *page = pvec.pages[i], *dpage;
271
272 lock_page(page);
273 if (unlikely(!PageDirty(page)))
274 NILFS_PAGE_BUG(page, "inconsistent dirty state");
275
276 dpage = grab_cache_page(dmap, page->index);
277 if (unlikely(!dpage)) {
278 /* No empty page is added to the page cache */
279 err = -ENOMEM;
280 unlock_page(page);
281 break;
282 }
283 if (unlikely(!page_has_buffers(page)))
284 NILFS_PAGE_BUG(page,
285 "found empty page in dat page cache");
286
287 nilfs_copy_page(dpage, page, 1);
288 __set_page_dirty_nobuffers(dpage);
289
290 unlock_page(dpage);
291 page_cache_release(dpage);
292 unlock_page(page);
293 }
294 pagevec_release(&pvec);
295 cond_resched();
296
297 if (likely(!err))
298 goto repeat;
299 return err;
300 }
301
302 /**
303 * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
304 * @dmap: destination page cache
305 * @smap: source page cache
306 *
307 * No pages must no be added to the cache during this process.
308 * This must be ensured by the caller.
309 */
nilfs_copy_back_pages(struct address_space * dmap,struct address_space * smap)310 void nilfs_copy_back_pages(struct address_space *dmap,
311 struct address_space *smap)
312 {
313 struct pagevec pvec;
314 unsigned int i, n;
315 pgoff_t index = 0;
316 int err;
317
318 pagevec_init(&pvec, 0);
319 repeat:
320 n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
321 if (!n)
322 return;
323 index = pvec.pages[n - 1]->index + 1;
324
325 for (i = 0; i < pagevec_count(&pvec); i++) {
326 struct page *page = pvec.pages[i], *dpage;
327 pgoff_t offset = page->index;
328
329 lock_page(page);
330 dpage = find_lock_page(dmap, offset);
331 if (dpage) {
332 /* override existing page on the destination cache */
333 WARN_ON(PageDirty(dpage));
334 nilfs_copy_page(dpage, page, 0);
335 unlock_page(dpage);
336 page_cache_release(dpage);
337 } else {
338 struct page *page2;
339
340 /* move the page to the destination cache */
341 spin_lock_irq(&smap->tree_lock);
342 page2 = radix_tree_delete(&smap->page_tree, offset);
343 WARN_ON(page2 != page);
344
345 smap->nrpages--;
346 spin_unlock_irq(&smap->tree_lock);
347
348 spin_lock_irq(&dmap->tree_lock);
349 err = radix_tree_insert(&dmap->page_tree, offset, page);
350 if (unlikely(err < 0)) {
351 WARN_ON(err == -EEXIST);
352 page->mapping = NULL;
353 page_cache_release(page); /* for cache */
354 } else {
355 page->mapping = dmap;
356 dmap->nrpages++;
357 if (PageDirty(page))
358 radix_tree_tag_set(&dmap->page_tree,
359 offset,
360 PAGECACHE_TAG_DIRTY);
361 }
362 spin_unlock_irq(&dmap->tree_lock);
363 }
364 unlock_page(page);
365 }
366 pagevec_release(&pvec);
367 cond_resched();
368
369 goto repeat;
370 }
371
372 /**
373 * nilfs_clear_dirty_pages - discard dirty pages in address space
374 * @mapping: address space with dirty pages for discarding
375 * @silent: suppress [true] or print [false] warning messages
376 */
nilfs_clear_dirty_pages(struct address_space * mapping,bool silent)377 void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
378 {
379 struct pagevec pvec;
380 unsigned int i;
381 pgoff_t index = 0;
382
383 pagevec_init(&pvec, 0);
384
385 while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
386 PAGEVEC_SIZE)) {
387 for (i = 0; i < pagevec_count(&pvec); i++) {
388 struct page *page = pvec.pages[i];
389
390 lock_page(page);
391 nilfs_clear_dirty_page(page, silent);
392 unlock_page(page);
393 }
394 pagevec_release(&pvec);
395 cond_resched();
396 }
397 }
398
399 /**
400 * nilfs_clear_dirty_page - discard dirty page
401 * @page: dirty page that will be discarded
402 * @silent: suppress [true] or print [false] warning messages
403 */
nilfs_clear_dirty_page(struct page * page,bool silent)404 void nilfs_clear_dirty_page(struct page *page, bool silent)
405 {
406 struct inode *inode = page->mapping->host;
407 struct super_block *sb = inode->i_sb;
408
409 BUG_ON(!PageLocked(page));
410
411 if (!silent) {
412 nilfs_warning(sb, __func__,
413 "discard page: offset %lld, ino %lu",
414 page_offset(page), inode->i_ino);
415 }
416
417 ClearPageUptodate(page);
418 ClearPageMappedToDisk(page);
419
420 if (page_has_buffers(page)) {
421 struct buffer_head *bh, *head;
422 const unsigned long clear_bits =
423 (1 << BH_Uptodate | 1 << BH_Dirty | 1 << BH_Mapped |
424 1 << BH_Async_Write | 1 << BH_NILFS_Volatile |
425 1 << BH_NILFS_Checked | 1 << BH_NILFS_Redirected);
426
427 bh = head = page_buffers(page);
428 do {
429 lock_buffer(bh);
430 if (!silent) {
431 nilfs_warning(sb, __func__,
432 "discard block %llu, size %zu",
433 (u64)bh->b_blocknr, bh->b_size);
434 }
435 set_mask_bits(&bh->b_state, clear_bits, 0);
436 unlock_buffer(bh);
437 } while (bh = bh->b_this_page, bh != head);
438 }
439
440 __nilfs_clear_page_dirty(page);
441 }
442
nilfs_page_count_clean_buffers(struct page * page,unsigned from,unsigned to)443 unsigned nilfs_page_count_clean_buffers(struct page *page,
444 unsigned from, unsigned to)
445 {
446 unsigned block_start, block_end;
447 struct buffer_head *bh, *head;
448 unsigned nc = 0;
449
450 for (bh = head = page_buffers(page), block_start = 0;
451 bh != head || !block_start;
452 block_start = block_end, bh = bh->b_this_page) {
453 block_end = block_start + bh->b_size;
454 if (block_end > from && block_start < to && !buffer_dirty(bh))
455 nc++;
456 }
457 return nc;
458 }
459
nilfs_mapping_init(struct address_space * mapping,struct inode * inode)460 void nilfs_mapping_init(struct address_space *mapping, struct inode *inode)
461 {
462 mapping->host = inode;
463 mapping->flags = 0;
464 mapping_set_gfp_mask(mapping, GFP_NOFS);
465 mapping->private_data = NULL;
466 mapping->a_ops = &empty_aops;
467 }
468
469 /*
470 * NILFS2 needs clear_page_dirty() in the following two cases:
471 *
472 * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
473 * page dirty flags when it copies back pages from the shadow cache
474 * (gcdat->{i_mapping,i_btnode_cache}) to its original cache
475 * (dat->{i_mapping,i_btnode_cache}).
476 *
477 * 2) Some B-tree operations like insertion or deletion may dispose buffers
478 * in dirty state, and this needs to cancel the dirty state of their pages.
479 */
__nilfs_clear_page_dirty(struct page * page)480 int __nilfs_clear_page_dirty(struct page *page)
481 {
482 struct address_space *mapping = page->mapping;
483
484 if (mapping) {
485 spin_lock_irq(&mapping->tree_lock);
486 if (test_bit(PG_dirty, &page->flags)) {
487 radix_tree_tag_clear(&mapping->page_tree,
488 page_index(page),
489 PAGECACHE_TAG_DIRTY);
490 spin_unlock_irq(&mapping->tree_lock);
491 return clear_page_dirty_for_io(page);
492 }
493 spin_unlock_irq(&mapping->tree_lock);
494 return 0;
495 }
496 return TestClearPageDirty(page);
497 }
498
499 /**
500 * nilfs_find_uncommitted_extent - find extent of uncommitted data
501 * @inode: inode
502 * @start_blk: start block offset (in)
503 * @blkoff: start offset of the found extent (out)
504 *
505 * This function searches an extent of buffers marked "delayed" which
506 * starts from a block offset equal to or larger than @start_blk. If
507 * such an extent was found, this will store the start offset in
508 * @blkoff and return its length in blocks. Otherwise, zero is
509 * returned.
510 */
nilfs_find_uncommitted_extent(struct inode * inode,sector_t start_blk,sector_t * blkoff)511 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
512 sector_t start_blk,
513 sector_t *blkoff)
514 {
515 unsigned int i;
516 pgoff_t index;
517 unsigned int nblocks_in_page;
518 unsigned long length = 0;
519 sector_t b;
520 struct pagevec pvec;
521 struct page *page;
522
523 if (inode->i_mapping->nrpages == 0)
524 return 0;
525
526 index = start_blk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
527 nblocks_in_page = 1U << (PAGE_CACHE_SHIFT - inode->i_blkbits);
528
529 pagevec_init(&pvec, 0);
530
531 repeat:
532 pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
533 pvec.pages);
534 if (pvec.nr == 0)
535 return length;
536
537 if (length > 0 && pvec.pages[0]->index > index)
538 goto out;
539
540 b = pvec.pages[0]->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
541 i = 0;
542 do {
543 page = pvec.pages[i];
544
545 lock_page(page);
546 if (page_has_buffers(page)) {
547 struct buffer_head *bh, *head;
548
549 bh = head = page_buffers(page);
550 do {
551 if (b < start_blk)
552 continue;
553 if (buffer_delay(bh)) {
554 if (length == 0)
555 *blkoff = b;
556 length++;
557 } else if (length > 0) {
558 goto out_locked;
559 }
560 } while (++b, bh = bh->b_this_page, bh != head);
561 } else {
562 if (length > 0)
563 goto out_locked;
564
565 b += nblocks_in_page;
566 }
567 unlock_page(page);
568
569 } while (++i < pagevec_count(&pvec));
570
571 index = page->index + 1;
572 pagevec_release(&pvec);
573 cond_resched();
574 goto repeat;
575
576 out_locked:
577 unlock_page(page);
578 out:
579 pagevec_release(&pvec);
580 return length;
581 }
582