sbshc: acpi_device_class "smbus_host_controller" too long
[linux-2.6.git] / fs / nilfs2 / page.c
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_Allocated))
41
42 static struct buffer_head *
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
61 /*
62  * Since the page cache of B-tree node pages or data page cache of pseudo
63  * inodes does not have a valid mapping->host pointer, calling
64  * mark_buffer_dirty() for their buffers causes a NULL pointer dereference;
65  * it calls __mark_inode_dirty(NULL) through __set_page_dirty().
66  * To avoid this problem, the old style mark_buffer_dirty() is used instead.
67  */
68 void nilfs_mark_buffer_dirty(struct buffer_head *bh)
69 {
70         if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
71                 __set_page_dirty_nobuffers(bh->b_page);
72 }
73
74 struct buffer_head *nilfs_grab_buffer(struct inode *inode,
75                                       struct address_space *mapping,
76                                       unsigned long blkoff,
77                                       unsigned long b_state)
78 {
79         int blkbits = inode->i_blkbits;
80         pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
81         struct page *page, *opage;
82         struct buffer_head *bh, *obh;
83
84         page = grab_cache_page(mapping, index);
85         if (unlikely(!page))
86                 return NULL;
87
88         bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
89         if (unlikely(!bh)) {
90                 unlock_page(page);
91                 page_cache_release(page);
92                 return NULL;
93         }
94         if (!buffer_uptodate(bh) && mapping->assoc_mapping != NULL) {
95                 /*
96                  * Shadow page cache uses assoc_mapping to point its original
97                  * page cache.  The following code tries the original cache
98                  * if the given cache is a shadow and it didn't hit.
99                  */
100                 opage = find_lock_page(mapping->assoc_mapping, index);
101                 if (!opage)
102                         return bh;
103
104                 obh = __nilfs_get_page_block(opage, blkoff, index, blkbits,
105                                              b_state);
106                 if (buffer_uptodate(obh)) {
107                         nilfs_copy_buffer(bh, obh);
108                         if (buffer_dirty(obh)) {
109                                 nilfs_mark_buffer_dirty(bh);
110                                 if (!buffer_nilfs_node(bh) && NILFS_MDT(inode))
111                                         nilfs_mdt_mark_dirty(inode);
112                         }
113                 }
114                 brelse(obh);
115                 unlock_page(opage);
116                 page_cache_release(opage);
117         }
118         return bh;
119 }
120
121 /**
122  * nilfs_forget_buffer - discard dirty state
123  * @inode: owner inode of the buffer
124  * @bh: buffer head of the buffer to be discarded
125  */
126 void nilfs_forget_buffer(struct buffer_head *bh)
127 {
128         struct page *page = bh->b_page;
129
130         lock_buffer(bh);
131         clear_buffer_nilfs_volatile(bh);
132         clear_buffer_dirty(bh);
133         if (nilfs_page_buffers_clean(page))
134                 __nilfs_clear_page_dirty(page);
135
136         clear_buffer_uptodate(bh);
137         clear_buffer_mapped(bh);
138         bh->b_blocknr = -1;
139         ClearPageUptodate(page);
140         ClearPageMappedToDisk(page);
141         unlock_buffer(bh);
142         brelse(bh);
143 }
144
145 /**
146  * nilfs_copy_buffer -- copy buffer data and flags
147  * @dbh: destination buffer
148  * @sbh: source buffer
149  */
150 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
151 {
152         void *kaddr0, *kaddr1;
153         unsigned long bits;
154         struct page *spage = sbh->b_page, *dpage = dbh->b_page;
155         struct buffer_head *bh;
156
157         kaddr0 = kmap_atomic(spage, KM_USER0);
158         kaddr1 = kmap_atomic(dpage, KM_USER1);
159         memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
160         kunmap_atomic(kaddr1, KM_USER1);
161         kunmap_atomic(kaddr0, KM_USER0);
162
163         dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
164         dbh->b_blocknr = sbh->b_blocknr;
165         dbh->b_bdev = sbh->b_bdev;
166
167         bh = dbh;
168         bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
169         while ((bh = bh->b_this_page) != dbh) {
170                 lock_buffer(bh);
171                 bits &= bh->b_state;
172                 unlock_buffer(bh);
173         }
174         if (bits & (1UL << BH_Uptodate))
175                 SetPageUptodate(dpage);
176         else
177                 ClearPageUptodate(dpage);
178         if (bits & (1UL << BH_Mapped))
179                 SetPageMappedToDisk(dpage);
180         else
181                 ClearPageMappedToDisk(dpage);
182 }
183
184 /**
185  * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
186  * @page: page to be checked
187  *
188  * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
189  * Otherwise, it returns non-zero value.
190  */
191 int nilfs_page_buffers_clean(struct page *page)
192 {
193         struct buffer_head *bh, *head;
194
195         bh = head = page_buffers(page);
196         do {
197                 if (buffer_dirty(bh))
198                         return 0;
199                 bh = bh->b_this_page;
200         } while (bh != head);
201         return 1;
202 }
203
204 void nilfs_page_bug(struct page *page)
205 {
206         struct address_space *m;
207         unsigned long ino = 0;
208
209         if (unlikely(!page)) {
210                 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
211                 return;
212         }
213
214         m = page->mapping;
215         if (m) {
216                 struct inode *inode = NILFS_AS_I(m);
217                 if (inode != NULL)
218                         ino = inode->i_ino;
219         }
220         printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
221                "mapping=%p ino=%lu\n",
222                page, atomic_read(&page->_count),
223                (unsigned long long)page->index, page->flags, m, ino);
224
225         if (page_has_buffers(page)) {
226                 struct buffer_head *bh, *head;
227                 int i = 0;
228
229                 bh = head = page_buffers(page);
230                 do {
231                         printk(KERN_CRIT
232                                " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
233                                i++, bh, atomic_read(&bh->b_count),
234                                (unsigned long long)bh->b_blocknr, bh->b_state);
235                         bh = bh->b_this_page;
236                 } while (bh != head);
237         }
238 }
239
240 /**
241  * nilfs_alloc_private_page - allocate a private page with buffer heads
242  *
243  * Return Value: On success, a pointer to the allocated page is returned.
244  * On error, NULL is returned.
245  */
246 struct page *nilfs_alloc_private_page(struct block_device *bdev, int size,
247                                       unsigned long state)
248 {
249         struct buffer_head *bh, *head, *tail;
250         struct page *page;
251
252         page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */
253         if (unlikely(!page))
254                 return NULL;
255
256         lock_page(page);
257         head = alloc_page_buffers(page, size, 0);
258         if (unlikely(!head)) {
259                 unlock_page(page);
260                 __free_page(page);
261                 return NULL;
262         }
263
264         bh = head;
265         do {
266                 bh->b_state = (1UL << BH_NILFS_Allocated) | state;
267                 tail = bh;
268                 bh->b_bdev = bdev;
269                 bh = bh->b_this_page;
270         } while (bh);
271
272         tail->b_this_page = head;
273         attach_page_buffers(page, head);
274
275         return page;
276 }
277
278 void nilfs_free_private_page(struct page *page)
279 {
280         BUG_ON(!PageLocked(page));
281         BUG_ON(page->mapping);
282
283         if (page_has_buffers(page) && !try_to_free_buffers(page))
284                 NILFS_PAGE_BUG(page, "failed to free page");
285
286         unlock_page(page);
287         __free_page(page);
288 }
289
290 /**
291  * nilfs_copy_page -- copy the page with buffers
292  * @dst: destination page
293  * @src: source page
294  * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
295  *
296  * This function is for both data pages and btnode pages.  The dirty flag
297  * should be treated by caller.  The page must not be under i/o.
298  * Both src and dst page must be locked
299  */
300 static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
301 {
302         struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
303         unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
304
305         BUG_ON(PageWriteback(dst));
306
307         sbh = sbufs = page_buffers(src);
308         if (!page_has_buffers(dst))
309                 create_empty_buffers(dst, sbh->b_size, 0);
310
311         if (copy_dirty)
312                 mask |= (1UL << BH_Dirty);
313
314         dbh = dbufs = page_buffers(dst);
315         do {
316                 lock_buffer(sbh);
317                 lock_buffer(dbh);
318                 dbh->b_state = sbh->b_state & mask;
319                 dbh->b_blocknr = sbh->b_blocknr;
320                 dbh->b_bdev = sbh->b_bdev;
321                 sbh = sbh->b_this_page;
322                 dbh = dbh->b_this_page;
323         } while (dbh != dbufs);
324
325         copy_highpage(dst, src);
326
327         if (PageUptodate(src) && !PageUptodate(dst))
328                 SetPageUptodate(dst);
329         else if (!PageUptodate(src) && PageUptodate(dst))
330                 ClearPageUptodate(dst);
331         if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
332                 SetPageMappedToDisk(dst);
333         else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
334                 ClearPageMappedToDisk(dst);
335
336         do {
337                 unlock_buffer(sbh);
338                 unlock_buffer(dbh);
339                 sbh = sbh->b_this_page;
340                 dbh = dbh->b_this_page;
341         } while (dbh != dbufs);
342 }
343
344 int nilfs_copy_dirty_pages(struct address_space *dmap,
345                            struct address_space *smap)
346 {
347         struct pagevec pvec;
348         unsigned int i;
349         pgoff_t index = 0;
350         int err = 0;
351
352         pagevec_init(&pvec, 0);
353 repeat:
354         if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
355                                 PAGEVEC_SIZE))
356                 return 0;
357
358         for (i = 0; i < pagevec_count(&pvec); i++) {
359                 struct page *page = pvec.pages[i], *dpage;
360
361                 lock_page(page);
362                 if (unlikely(!PageDirty(page)))
363                         NILFS_PAGE_BUG(page, "inconsistent dirty state");
364
365                 dpage = grab_cache_page(dmap, page->index);
366                 if (unlikely(!dpage)) {
367                         /* No empty page is added to the page cache */
368                         err = -ENOMEM;
369                         unlock_page(page);
370                         break;
371                 }
372                 if (unlikely(!page_has_buffers(page)))
373                         NILFS_PAGE_BUG(page,
374                                        "found empty page in dat page cache");
375
376                 nilfs_copy_page(dpage, page, 1);
377                 __set_page_dirty_nobuffers(dpage);
378
379                 unlock_page(dpage);
380                 page_cache_release(dpage);
381                 unlock_page(page);
382         }
383         pagevec_release(&pvec);
384         cond_resched();
385
386         if (likely(!err))
387                 goto repeat;
388         return err;
389 }
390
391 /**
392  * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
393  * @dmap: destination page cache
394  * @smap: source page cache
395  *
396  * No pages must no be added to the cache during this process.
397  * This must be ensured by the caller.
398  */
399 void nilfs_copy_back_pages(struct address_space *dmap,
400                            struct address_space *smap)
401 {
402         struct pagevec pvec;
403         unsigned int i, n;
404         pgoff_t index = 0;
405         int err;
406
407         pagevec_init(&pvec, 0);
408 repeat:
409         n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
410         if (!n)
411                 return;
412         index = pvec.pages[n - 1]->index + 1;
413
414         for (i = 0; i < pagevec_count(&pvec); i++) {
415                 struct page *page = pvec.pages[i], *dpage;
416                 pgoff_t offset = page->index;
417
418                 lock_page(page);
419                 dpage = find_lock_page(dmap, offset);
420                 if (dpage) {
421                         /* override existing page on the destination cache */
422                         WARN_ON(PageDirty(dpage));
423                         nilfs_copy_page(dpage, page, 0);
424                         unlock_page(dpage);
425                         page_cache_release(dpage);
426                 } else {
427                         struct page *page2;
428
429                         /* move the page to the destination cache */
430                         spin_lock_irq(&smap->tree_lock);
431                         page2 = radix_tree_delete(&smap->page_tree, offset);
432                         WARN_ON(page2 != page);
433
434                         smap->nrpages--;
435                         spin_unlock_irq(&smap->tree_lock);
436
437                         spin_lock_irq(&dmap->tree_lock);
438                         err = radix_tree_insert(&dmap->page_tree, offset, page);
439                         if (unlikely(err < 0)) {
440                                 WARN_ON(err == -EEXIST);
441                                 page->mapping = NULL;
442                                 page_cache_release(page); /* for cache */
443                         } else {
444                                 page->mapping = dmap;
445                                 dmap->nrpages++;
446                                 if (PageDirty(page))
447                                         radix_tree_tag_set(&dmap->page_tree,
448                                                            offset,
449                                                            PAGECACHE_TAG_DIRTY);
450                         }
451                         spin_unlock_irq(&dmap->tree_lock);
452                 }
453                 unlock_page(page);
454         }
455         pagevec_release(&pvec);
456         cond_resched();
457
458         goto repeat;
459 }
460
461 void nilfs_clear_dirty_pages(struct address_space *mapping)
462 {
463         struct pagevec pvec;
464         unsigned int i;
465         pgoff_t index = 0;
466
467         pagevec_init(&pvec, 0);
468
469         while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
470                                   PAGEVEC_SIZE)) {
471                 for (i = 0; i < pagevec_count(&pvec); i++) {
472                         struct page *page = pvec.pages[i];
473                         struct buffer_head *bh, *head;
474
475                         lock_page(page);
476                         ClearPageUptodate(page);
477                         ClearPageMappedToDisk(page);
478                         bh = head = page_buffers(page);
479                         do {
480                                 lock_buffer(bh);
481                                 clear_buffer_dirty(bh);
482                                 clear_buffer_nilfs_volatile(bh);
483                                 clear_buffer_uptodate(bh);
484                                 clear_buffer_mapped(bh);
485                                 unlock_buffer(bh);
486                                 bh = bh->b_this_page;
487                         } while (bh != head);
488
489                         __nilfs_clear_page_dirty(page);
490                         unlock_page(page);
491                 }
492                 pagevec_release(&pvec);
493                 cond_resched();
494         }
495 }
496
497 unsigned nilfs_page_count_clean_buffers(struct page *page,
498                                         unsigned from, unsigned to)
499 {
500         unsigned block_start, block_end;
501         struct buffer_head *bh, *head;
502         unsigned nc = 0;
503
504         for (bh = head = page_buffers(page), block_start = 0;
505              bh != head || !block_start;
506              block_start = block_end, bh = bh->b_this_page) {
507                 block_end = block_start + bh->b_size;
508                 if (block_end > from && block_start < to && !buffer_dirty(bh))
509                         nc++;
510         }
511         return nc;
512 }
513
514 /*
515  * NILFS2 needs clear_page_dirty() in the following two cases:
516  *
517  * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
518  *    page dirty flags when it copies back pages from the shadow cache
519  *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
520  *    (dat->{i_mapping,i_btnode_cache}).
521  *
522  * 2) Some B-tree operations like insertion or deletion may dispose buffers
523  *    in dirty state, and this needs to cancel the dirty state of their pages.
524  */
525 int __nilfs_clear_page_dirty(struct page *page)
526 {
527         struct address_space *mapping = page->mapping;
528
529         if (mapping) {
530                 spin_lock_irq(&mapping->tree_lock);
531                 if (test_bit(PG_dirty, &page->flags)) {
532                         radix_tree_tag_clear(&mapping->page_tree,
533                                              page_index(page),
534                                              PAGECACHE_TAG_DIRTY);
535                         spin_unlock_irq(&mapping->tree_lock);
536                         return clear_page_dirty_for_io(page);
537                 }
538                 spin_unlock_irq(&mapping->tree_lock);
539                 return 0;
540         }
541         return TestClearPageDirty(page);
542 }