blob: 1bfbba9c0e9ae3aba969e6c3341968ce24916a7d [file] [log] [blame]
Ryusuke Konishi0bd49f92009-04-06 19:01:27 -07001/*
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 "nilfs.h"
33#include "page.h"
34#include "mdt.h"
35
36
37#define NILFS_BUFFER_INHERENT_BITS \
38 ((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \
39 (1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Allocated))
40
41static struct buffer_head *
42__nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
43 int blkbits, unsigned long b_state)
44
45{
46 unsigned long first_block;
47 struct buffer_head *bh;
48
49 if (!page_has_buffers(page))
50 create_empty_buffers(page, 1 << blkbits, b_state);
51
52 first_block = (unsigned long)index << (PAGE_CACHE_SHIFT - blkbits);
53 bh = nilfs_page_get_nth_block(page, block - first_block);
54
55 touch_buffer(bh);
56 wait_on_buffer(bh);
57 return bh;
58}
59
60/*
61 * Since the page cache of B-tree node pages or data page cache of pseudo
62 * inodes does not have a valid mapping->host pointer, calling
63 * mark_buffer_dirty() for their buffers causes a NULL pointer dereference;
64 * it calls __mark_inode_dirty(NULL) through __set_page_dirty().
65 * To avoid this problem, the old style mark_buffer_dirty() is used instead.
66 */
67void nilfs_mark_buffer_dirty(struct buffer_head *bh)
68{
69 if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
70 __set_page_dirty_nobuffers(bh->b_page);
71}
72
73struct buffer_head *nilfs_grab_buffer(struct inode *inode,
74 struct address_space *mapping,
75 unsigned long blkoff,
76 unsigned long b_state)
77{
78 int blkbits = inode->i_blkbits;
79 pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
80 struct page *page, *opage;
81 struct buffer_head *bh, *obh;
82
83 page = grab_cache_page(mapping, index);
84 if (unlikely(!page))
85 return NULL;
86
87 bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
88 if (unlikely(!bh)) {
89 unlock_page(page);
90 page_cache_release(page);
91 return NULL;
92 }
93 if (!buffer_uptodate(bh) && mapping->assoc_mapping != NULL) {
94 /*
95 * Shadow page cache uses assoc_mapping to point its original
96 * page cache. The following code tries the original cache
97 * if the given cache is a shadow and it didn't hit.
98 */
99 opage = find_lock_page(mapping->assoc_mapping, index);
100 if (!opage)
101 return bh;
102
103 obh = __nilfs_get_page_block(opage, blkoff, index, blkbits,
104 b_state);
105 if (buffer_uptodate(obh)) {
106 nilfs_copy_buffer(bh, obh);
107 if (buffer_dirty(obh)) {
108 nilfs_mark_buffer_dirty(bh);
109 if (!buffer_nilfs_node(bh) && NILFS_MDT(inode))
110 nilfs_mdt_mark_dirty(inode);
111 }
112 }
113 brelse(obh);
114 unlock_page(opage);
115 page_cache_release(opage);
116 }
117 return bh;
118}
119
120/**
121 * nilfs_forget_buffer - discard dirty state
122 * @inode: owner inode of the buffer
123 * @bh: buffer head of the buffer to be discarded
124 */
125void nilfs_forget_buffer(struct buffer_head *bh)
126{
127 struct page *page = bh->b_page;
128
129 lock_buffer(bh);
130 clear_buffer_nilfs_volatile(bh);
131 if (test_clear_buffer_dirty(bh) && nilfs_page_buffers_clean(page))
132 __nilfs_clear_page_dirty(page);
133
134 clear_buffer_uptodate(bh);
135 clear_buffer_mapped(bh);
136 bh->b_blocknr = -1;
137 ClearPageUptodate(page);
138 ClearPageMappedToDisk(page);
139 unlock_buffer(bh);
140 brelse(bh);
141}
142
143/**
144 * nilfs_copy_buffer -- copy buffer data and flags
145 * @dbh: destination buffer
146 * @sbh: source buffer
147 */
148void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
149{
150 void *kaddr0, *kaddr1;
151 unsigned long bits;
152 struct page *spage = sbh->b_page, *dpage = dbh->b_page;
153 struct buffer_head *bh;
154
155 kaddr0 = kmap_atomic(spage, KM_USER0);
156 kaddr1 = kmap_atomic(dpage, KM_USER1);
157 memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
158 kunmap_atomic(kaddr1, KM_USER1);
159 kunmap_atomic(kaddr0, KM_USER0);
160
161 dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
162 dbh->b_blocknr = sbh->b_blocknr;
163 dbh->b_bdev = sbh->b_bdev;
164
165 bh = dbh;
166 bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
167 while ((bh = bh->b_this_page) != dbh) {
168 lock_buffer(bh);
169 bits &= bh->b_state;
170 unlock_buffer(bh);
171 }
172 if (bits & (1UL << BH_Uptodate))
173 SetPageUptodate(dpage);
174 else
175 ClearPageUptodate(dpage);
176 if (bits & (1UL << BH_Mapped))
177 SetPageMappedToDisk(dpage);
178 else
179 ClearPageMappedToDisk(dpage);
180}
181
182/**
183 * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
184 * @page: page to be checked
185 *
186 * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
187 * Otherwise, it returns non-zero value.
188 */
189int nilfs_page_buffers_clean(struct page *page)
190{
191 struct buffer_head *bh, *head;
192
193 bh = head = page_buffers(page);
194 do {
195 if (buffer_dirty(bh))
196 return 0;
197 bh = bh->b_this_page;
198 } while (bh != head);
199 return 1;
200}
201
202void nilfs_page_bug(struct page *page)
203{
204 struct address_space *m;
205 unsigned long ino = 0;
206
207 if (unlikely(!page)) {
208 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
209 return;
210 }
211
212 m = page->mapping;
213 if (m) {
214 struct inode *inode = NILFS_AS_I(m);
215 if (inode != NULL)
216 ino = inode->i_ino;
217 }
218 printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
219 "mapping=%p ino=%lu\n",
220 page, atomic_read(&page->_count),
221 (unsigned long long)page->index, page->flags, m, ino);
222
223 if (page_has_buffers(page)) {
224 struct buffer_head *bh, *head;
225 int i = 0;
226
227 bh = head = page_buffers(page);
228 do {
229 printk(KERN_CRIT
230 " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
231 i++, bh, atomic_read(&bh->b_count),
232 (unsigned long long)bh->b_blocknr, bh->b_state);
233 bh = bh->b_this_page;
234 } while (bh != head);
235 }
236}
237
238/**
239 * nilfs_alloc_private_page - allocate a private page with buffer heads
240 *
241 * Return Value: On success, a pointer to the allocated page is returned.
242 * On error, NULL is returned.
243 */
244struct page *nilfs_alloc_private_page(struct block_device *bdev, int size,
245 unsigned long state)
246{
247 struct buffer_head *bh, *head, *tail;
248 struct page *page;
249
250 page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */
251 if (unlikely(!page))
252 return NULL;
253
254 lock_page(page);
255 head = alloc_page_buffers(page, size, 0);
256 if (unlikely(!head)) {
257 unlock_page(page);
258 __free_page(page);
259 return NULL;
260 }
261
262 bh = head;
263 do {
264 bh->b_state = (1UL << BH_NILFS_Allocated) | state;
265 tail = bh;
266 bh->b_bdev = bdev;
267 bh = bh->b_this_page;
268 } while (bh);
269
270 tail->b_this_page = head;
271 attach_page_buffers(page, head);
272
273 return page;
274}
275
276void nilfs_free_private_page(struct page *page)
277{
278 BUG_ON(!PageLocked(page));
279 BUG_ON(page->mapping);
280
281 if (page_has_buffers(page) && !try_to_free_buffers(page))
282 NILFS_PAGE_BUG(page, "failed to free page");
283
284 unlock_page(page);
285 __free_page(page);
286}
287
288/**
289 * nilfs_copy_page -- copy the page with buffers
290 * @dst: destination page
291 * @src: source page
292 * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
293 *
294 * This fuction is for both data pages and btnode pages. The dirty flag
295 * should be treated by caller. The page must not be under i/o.
296 * Both src and dst page must be locked
297 */
298static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
299{
300 struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
301 unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
302
303 BUG_ON(PageWriteback(dst));
304
305 sbh = sbufs = page_buffers(src);
306 if (!page_has_buffers(dst))
307 create_empty_buffers(dst, sbh->b_size, 0);
308
309 if (copy_dirty)
310 mask |= (1UL << BH_Dirty);
311
312 dbh = dbufs = page_buffers(dst);
313 do {
314 lock_buffer(sbh);
315 lock_buffer(dbh);
316 dbh->b_state = sbh->b_state & mask;
317 dbh->b_blocknr = sbh->b_blocknr;
318 dbh->b_bdev = sbh->b_bdev;
319 sbh = sbh->b_this_page;
320 dbh = dbh->b_this_page;
321 } while (dbh != dbufs);
322
323 copy_highpage(dst, src);
324
325 if (PageUptodate(src) && !PageUptodate(dst))
326 SetPageUptodate(dst);
327 else if (!PageUptodate(src) && PageUptodate(dst))
328 ClearPageUptodate(dst);
329 if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
330 SetPageMappedToDisk(dst);
331 else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
332 ClearPageMappedToDisk(dst);
333
334 do {
335 unlock_buffer(sbh);
336 unlock_buffer(dbh);
337 sbh = sbh->b_this_page;
338 dbh = dbh->b_this_page;
339 } while (dbh != dbufs);
340}
341
342int nilfs_copy_dirty_pages(struct address_space *dmap,
343 struct address_space *smap)
344{
345 struct pagevec pvec;
346 unsigned int i;
347 pgoff_t index = 0;
348 int err = 0;
349
350 pagevec_init(&pvec, 0);
351repeat:
352 if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
353 PAGEVEC_SIZE))
354 return 0;
355
356 for (i = 0; i < pagevec_count(&pvec); i++) {
357 struct page *page = pvec.pages[i], *dpage;
358
359 lock_page(page);
360 if (unlikely(!PageDirty(page)))
361 NILFS_PAGE_BUG(page, "inconsistent dirty state");
362
363 dpage = grab_cache_page(dmap, page->index);
364 if (unlikely(!dpage)) {
365 /* No empty page is added to the page cache */
366 err = -ENOMEM;
367 unlock_page(page);
368 break;
369 }
370 if (unlikely(!page_has_buffers(page)))
371 NILFS_PAGE_BUG(page,
372 "found empty page in dat page cache");
373
374 nilfs_copy_page(dpage, page, 1);
375 __set_page_dirty_nobuffers(dpage);
376
377 unlock_page(dpage);
378 page_cache_release(dpage);
379 unlock_page(page);
380 }
381 pagevec_release(&pvec);
382 cond_resched();
383
384 if (likely(!err))
385 goto repeat;
386 return err;
387}
388
389/**
390 * nilfs_copy_back_pages -- copy back pages to orignal cache from shadow cache
391 * @dmap: destination page cache
392 * @smap: source page cache
393 *
394 * No pages must no be added to the cache during this process.
395 * This must be ensured by the caller.
396 */
397void nilfs_copy_back_pages(struct address_space *dmap,
398 struct address_space *smap)
399{
400 struct pagevec pvec;
401 unsigned int i, n;
402 pgoff_t index = 0;
403 int err;
404
405 pagevec_init(&pvec, 0);
406repeat:
407 n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
408 if (!n)
409 return;
410 index = pvec.pages[n - 1]->index + 1;
411
412 for (i = 0; i < pagevec_count(&pvec); i++) {
413 struct page *page = pvec.pages[i], *dpage;
414 pgoff_t offset = page->index;
415
416 lock_page(page);
417 dpage = find_lock_page(dmap, offset);
418 if (dpage) {
419 /* override existing page on the destination cache */
Ryusuke Konishi1f5abe72009-04-06 19:01:55 -0700420 WARN_ON(PageDirty(dpage));
Ryusuke Konishi0bd49f92009-04-06 19:01:27 -0700421 nilfs_copy_page(dpage, page, 0);
422 unlock_page(dpage);
423 page_cache_release(dpage);
424 } else {
425 struct page *page2;
426
427 /* move the page to the destination cache */
428 spin_lock_irq(&smap->tree_lock);
429 page2 = radix_tree_delete(&smap->page_tree, offset);
Ryusuke Konishi1f5abe72009-04-06 19:01:55 -0700430 WARN_ON(page2 != page);
431
Ryusuke Konishi0bd49f92009-04-06 19:01:27 -0700432 smap->nrpages--;
433 spin_unlock_irq(&smap->tree_lock);
434
435 spin_lock_irq(&dmap->tree_lock);
436 err = radix_tree_insert(&dmap->page_tree, offset, page);
437 if (unlikely(err < 0)) {
Ryusuke Konishi1f5abe72009-04-06 19:01:55 -0700438 WARN_ON(err == -EEXIST);
Ryusuke Konishi0bd49f92009-04-06 19:01:27 -0700439 page->mapping = NULL;
440 page_cache_release(page); /* for cache */
441 } else {
442 page->mapping = dmap;
443 dmap->nrpages++;
444 if (PageDirty(page))
445 radix_tree_tag_set(&dmap->page_tree,
446 offset,
447 PAGECACHE_TAG_DIRTY);
448 }
449 spin_unlock_irq(&dmap->tree_lock);
450 }
451 unlock_page(page);
452 }
453 pagevec_release(&pvec);
454 cond_resched();
455
456 goto repeat;
457}
458
459void nilfs_clear_dirty_pages(struct address_space *mapping)
460{
461 struct pagevec pvec;
462 unsigned int i;
463 pgoff_t index = 0;
464
465 pagevec_init(&pvec, 0);
466
467 while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
468 PAGEVEC_SIZE)) {
469 for (i = 0; i < pagevec_count(&pvec); i++) {
470 struct page *page = pvec.pages[i];
471 struct buffer_head *bh, *head;
472
473 lock_page(page);
474 ClearPageUptodate(page);
475 ClearPageMappedToDisk(page);
476 bh = head = page_buffers(page);
477 do {
478 lock_buffer(bh);
479 clear_buffer_dirty(bh);
480 clear_buffer_nilfs_volatile(bh);
481 clear_buffer_uptodate(bh);
482 clear_buffer_mapped(bh);
483 unlock_buffer(bh);
484 bh = bh->b_this_page;
485 } while (bh != head);
486
487 __nilfs_clear_page_dirty(page);
488 unlock_page(page);
489 }
490 pagevec_release(&pvec);
491 cond_resched();
492 }
493}
494
495unsigned nilfs_page_count_clean_buffers(struct page *page,
496 unsigned from, unsigned to)
497{
498 unsigned block_start, block_end;
499 struct buffer_head *bh, *head;
500 unsigned nc = 0;
501
502 for (bh = head = page_buffers(page), block_start = 0;
503 bh != head || !block_start;
504 block_start = block_end, bh = bh->b_this_page) {
505 block_end = block_start + bh->b_size;
506 if (block_end > from && block_start < to && !buffer_dirty(bh))
507 nc++;
508 }
509 return nc;
510}
511
512/*
513 * NILFS2 needs clear_page_dirty() in the following two cases:
514 *
515 * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
516 * page dirty flags when it copies back pages from the shadow cache
517 * (gcdat->{i_mapping,i_btnode_cache}) to its original cache
518 * (dat->{i_mapping,i_btnode_cache}).
519 *
520 * 2) Some B-tree operations like insertion or deletion may dispose buffers
521 * in dirty state, and this needs to cancel the dirty state of their pages.
522 */
523int __nilfs_clear_page_dirty(struct page *page)
524{
525 struct address_space *mapping = page->mapping;
526
527 if (mapping) {
528 spin_lock_irq(&mapping->tree_lock);
529 if (test_bit(PG_dirty, &page->flags)) {
530 radix_tree_tag_clear(&mapping->page_tree,
531 page_index(page),
532 PAGECACHE_TAG_DIRTY);
533 spin_unlock_irq(&mapping->tree_lock);
534 return clear_page_dirty_for_io(page);
535 }
536 spin_unlock_irq(&mapping->tree_lock);
537 return 0;
538 }
539 return TestClearPageDirty(page);
540}