1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Buffer/page management specific to NILFS
4 *
5 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
6 *
7 * Written by Ryusuke Konishi and Seiji Kihara.
8 */
9
10 #include <linux/pagemap.h>
11 #include <linux/writeback.h>
12 #include <linux/swap.h>
13 #include <linux/bitops.h>
14 #include <linux/page-flags.h>
15 #include <linux/list.h>
16 #include <linux/highmem.h>
17 #include <linux/pagevec.h>
18 #include <linux/gfp.h>
19 #include "nilfs.h"
20 #include "page.h"
21 #include "mdt.h"
22
23
24 #define NILFS_BUFFER_INHERENT_BITS \
25 (BIT(BH_Uptodate) | BIT(BH_Mapped) | BIT(BH_NILFS_Node) | \
26 BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Checked))
27
28 static struct buffer_head *
__nilfs_get_page_block(struct page * page,unsigned long block,pgoff_t index,int blkbits,unsigned long b_state)29 __nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
30 int blkbits, unsigned long b_state)
31
32 {
33 unsigned long first_block;
34 struct buffer_head *bh;
35
36 if (!page_has_buffers(page))
37 create_empty_buffers(page, 1 << blkbits, b_state);
38
39 first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
40 bh = nilfs_page_get_nth_block(page, block - first_block);
41
42 touch_buffer(bh);
43 wait_on_buffer(bh);
44 return bh;
45 }
46
nilfs_grab_buffer(struct inode * inode,struct address_space * mapping,unsigned long blkoff,unsigned long b_state)47 struct buffer_head *nilfs_grab_buffer(struct inode *inode,
48 struct address_space *mapping,
49 unsigned long blkoff,
50 unsigned long b_state)
51 {
52 int blkbits = inode->i_blkbits;
53 pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
54 struct page *page;
55 struct buffer_head *bh;
56
57 page = grab_cache_page(mapping, index);
58 if (unlikely(!page))
59 return NULL;
60
61 bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
62 if (unlikely(!bh)) {
63 unlock_page(page);
64 put_page(page);
65 return NULL;
66 }
67 return bh;
68 }
69
70 /**
71 * nilfs_forget_buffer - discard dirty state
72 * @bh: buffer head of the buffer to be discarded
73 */
nilfs_forget_buffer(struct buffer_head * bh)74 void nilfs_forget_buffer(struct buffer_head *bh)
75 {
76 struct page *page = bh->b_page;
77 const unsigned long clear_bits =
78 (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
79 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
80 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
81
82 lock_buffer(bh);
83 set_mask_bits(&bh->b_state, clear_bits, 0);
84 if (nilfs_page_buffers_clean(page))
85 __nilfs_clear_page_dirty(page);
86
87 bh->b_blocknr = -1;
88 ClearPageUptodate(page);
89 ClearPageMappedToDisk(page);
90 unlock_buffer(bh);
91 brelse(bh);
92 }
93
94 /**
95 * nilfs_copy_buffer -- copy buffer data and flags
96 * @dbh: destination buffer
97 * @sbh: source buffer
98 */
nilfs_copy_buffer(struct buffer_head * dbh,struct buffer_head * sbh)99 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
100 {
101 void *kaddr0, *kaddr1;
102 unsigned long bits;
103 struct page *spage = sbh->b_page, *dpage = dbh->b_page;
104 struct buffer_head *bh;
105
106 kaddr0 = kmap_atomic(spage);
107 kaddr1 = kmap_atomic(dpage);
108 memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
109 kunmap_atomic(kaddr1);
110 kunmap_atomic(kaddr0);
111
112 dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
113 dbh->b_blocknr = sbh->b_blocknr;
114 dbh->b_bdev = sbh->b_bdev;
115
116 bh = dbh;
117 bits = sbh->b_state & (BIT(BH_Uptodate) | BIT(BH_Mapped));
118 while ((bh = bh->b_this_page) != dbh) {
119 lock_buffer(bh);
120 bits &= bh->b_state;
121 unlock_buffer(bh);
122 }
123 if (bits & BIT(BH_Uptodate))
124 SetPageUptodate(dpage);
125 else
126 ClearPageUptodate(dpage);
127 if (bits & BIT(BH_Mapped))
128 SetPageMappedToDisk(dpage);
129 else
130 ClearPageMappedToDisk(dpage);
131 }
132
133 /**
134 * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
135 * @page: page to be checked
136 *
137 * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
138 * Otherwise, it returns non-zero value.
139 */
nilfs_page_buffers_clean(struct page * page)140 int nilfs_page_buffers_clean(struct page *page)
141 {
142 struct buffer_head *bh, *head;
143
144 bh = head = page_buffers(page);
145 do {
146 if (buffer_dirty(bh))
147 return 0;
148 bh = bh->b_this_page;
149 } while (bh != head);
150 return 1;
151 }
152
nilfs_page_bug(struct page * page)153 void nilfs_page_bug(struct page *page)
154 {
155 struct address_space *m;
156 unsigned long ino;
157
158 if (unlikely(!page)) {
159 printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
160 return;
161 }
162
163 m = page->mapping;
164 ino = m ? m->host->i_ino : 0;
165
166 printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
167 "mapping=%p ino=%lu\n",
168 page, page_ref_count(page),
169 (unsigned long long)page->index, page->flags, m, ino);
170
171 if (page_has_buffers(page)) {
172 struct buffer_head *bh, *head;
173 int i = 0;
174
175 bh = head = page_buffers(page);
176 do {
177 printk(KERN_CRIT
178 " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
179 i++, bh, atomic_read(&bh->b_count),
180 (unsigned long long)bh->b_blocknr, bh->b_state);
181 bh = bh->b_this_page;
182 } while (bh != head);
183 }
184 }
185
186 /**
187 * nilfs_copy_page -- copy the page with buffers
188 * @dst: destination page
189 * @src: source page
190 * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
191 *
192 * This function is for both data pages and btnode pages. The dirty flag
193 * should be treated by caller. The page must not be under i/o.
194 * Both src and dst page must be locked
195 */
nilfs_copy_page(struct page * dst,struct page * src,int copy_dirty)196 static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
197 {
198 struct buffer_head *dbh, *dbufs, *sbh;
199 unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
200
201 BUG_ON(PageWriteback(dst));
202
203 sbh = page_buffers(src);
204 if (!page_has_buffers(dst))
205 create_empty_buffers(dst, sbh->b_size, 0);
206
207 if (copy_dirty)
208 mask |= BIT(BH_Dirty);
209
210 dbh = dbufs = page_buffers(dst);
211 do {
212 lock_buffer(sbh);
213 lock_buffer(dbh);
214 dbh->b_state = sbh->b_state & mask;
215 dbh->b_blocknr = sbh->b_blocknr;
216 dbh->b_bdev = sbh->b_bdev;
217 sbh = sbh->b_this_page;
218 dbh = dbh->b_this_page;
219 } while (dbh != dbufs);
220
221 copy_highpage(dst, src);
222
223 if (PageUptodate(src) && !PageUptodate(dst))
224 SetPageUptodate(dst);
225 else if (!PageUptodate(src) && PageUptodate(dst))
226 ClearPageUptodate(dst);
227 if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
228 SetPageMappedToDisk(dst);
229 else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
230 ClearPageMappedToDisk(dst);
231
232 do {
233 unlock_buffer(sbh);
234 unlock_buffer(dbh);
235 sbh = sbh->b_this_page;
236 dbh = dbh->b_this_page;
237 } while (dbh != dbufs);
238 }
239
nilfs_copy_dirty_pages(struct address_space * dmap,struct address_space * smap)240 int nilfs_copy_dirty_pages(struct address_space *dmap,
241 struct address_space *smap)
242 {
243 struct folio_batch fbatch;
244 unsigned int i;
245 pgoff_t index = 0;
246 int err = 0;
247
248 folio_batch_init(&fbatch);
249 repeat:
250 if (!filemap_get_folios_tag(smap, &index, (pgoff_t)-1,
251 PAGECACHE_TAG_DIRTY, &fbatch))
252 return 0;
253
254 for (i = 0; i < folio_batch_count(&fbatch); i++) {
255 struct folio *folio = fbatch.folios[i], *dfolio;
256
257 folio_lock(folio);
258 if (unlikely(!folio_test_dirty(folio)))
259 NILFS_PAGE_BUG(&folio->page, "inconsistent dirty state");
260
261 dfolio = filemap_grab_folio(dmap, folio->index);
262 if (unlikely(IS_ERR(dfolio))) {
263 /* No empty page is added to the page cache */
264 folio_unlock(folio);
265 err = PTR_ERR(dfolio);
266 break;
267 }
268 if (unlikely(!folio_buffers(folio)))
269 NILFS_PAGE_BUG(&folio->page,
270 "found empty page in dat page cache");
271
272 nilfs_copy_page(&dfolio->page, &folio->page, 1);
273 filemap_dirty_folio(folio_mapping(dfolio), dfolio);
274
275 folio_unlock(dfolio);
276 folio_put(dfolio);
277 folio_unlock(folio);
278 }
279 folio_batch_release(&fbatch);
280 cond_resched();
281
282 if (likely(!err))
283 goto repeat;
284 return err;
285 }
286
287 /**
288 * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
289 * @dmap: destination page cache
290 * @smap: source page cache
291 *
292 * No pages must be added to the cache during this process.
293 * This must be ensured by the caller.
294 */
nilfs_copy_back_pages(struct address_space * dmap,struct address_space * smap)295 void nilfs_copy_back_pages(struct address_space *dmap,
296 struct address_space *smap)
297 {
298 struct folio_batch fbatch;
299 unsigned int i, n;
300 pgoff_t start = 0;
301
302 folio_batch_init(&fbatch);
303 repeat:
304 n = filemap_get_folios(smap, &start, ~0UL, &fbatch);
305 if (!n)
306 return;
307
308 for (i = 0; i < folio_batch_count(&fbatch); i++) {
309 struct folio *folio = fbatch.folios[i], *dfolio;
310 pgoff_t index = folio->index;
311
312 folio_lock(folio);
313 dfolio = filemap_lock_folio(dmap, index);
314 if (!IS_ERR(dfolio)) {
315 /* overwrite existing folio in the destination cache */
316 WARN_ON(folio_test_dirty(dfolio));
317 nilfs_copy_page(&dfolio->page, &folio->page, 0);
318 folio_unlock(dfolio);
319 folio_put(dfolio);
320 /* Do we not need to remove folio from smap here? */
321 } else {
322 struct folio *f;
323
324 /* move the folio to the destination cache */
325 xa_lock_irq(&smap->i_pages);
326 f = __xa_erase(&smap->i_pages, index);
327 WARN_ON(folio != f);
328 smap->nrpages--;
329 xa_unlock_irq(&smap->i_pages);
330
331 xa_lock_irq(&dmap->i_pages);
332 f = __xa_store(&dmap->i_pages, index, folio, GFP_NOFS);
333 if (unlikely(f)) {
334 /* Probably -ENOMEM */
335 folio->mapping = NULL;
336 folio_put(folio);
337 } else {
338 folio->mapping = dmap;
339 dmap->nrpages++;
340 if (folio_test_dirty(folio))
341 __xa_set_mark(&dmap->i_pages, index,
342 PAGECACHE_TAG_DIRTY);
343 }
344 xa_unlock_irq(&dmap->i_pages);
345 }
346 folio_unlock(folio);
347 }
348 folio_batch_release(&fbatch);
349 cond_resched();
350
351 goto repeat;
352 }
353
354 /**
355 * nilfs_clear_dirty_pages - discard dirty pages in address space
356 * @mapping: address space with dirty pages for discarding
357 * @silent: suppress [true] or print [false] warning messages
358 */
nilfs_clear_dirty_pages(struct address_space * mapping,bool silent)359 void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
360 {
361 struct folio_batch fbatch;
362 unsigned int i;
363 pgoff_t index = 0;
364
365 folio_batch_init(&fbatch);
366
367 while (filemap_get_folios_tag(mapping, &index, (pgoff_t)-1,
368 PAGECACHE_TAG_DIRTY, &fbatch)) {
369 for (i = 0; i < folio_batch_count(&fbatch); i++) {
370 struct folio *folio = fbatch.folios[i];
371
372 folio_lock(folio);
373
374 /*
375 * This folio may have been removed from the address
376 * space by truncation or invalidation when the lock
377 * was acquired. Skip processing in that case.
378 */
379 if (likely(folio->mapping == mapping))
380 nilfs_clear_dirty_page(&folio->page, silent);
381
382 folio_unlock(folio);
383 }
384 folio_batch_release(&fbatch);
385 cond_resched();
386 }
387 }
388
389 /**
390 * nilfs_clear_dirty_page - discard dirty page
391 * @page: dirty page that will be discarded
392 * @silent: suppress [true] or print [false] warning messages
393 */
nilfs_clear_dirty_page(struct page * page,bool silent)394 void nilfs_clear_dirty_page(struct page *page, bool silent)
395 {
396 struct inode *inode = page->mapping->host;
397 struct super_block *sb = inode->i_sb;
398
399 BUG_ON(!PageLocked(page));
400
401 if (!silent)
402 nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu",
403 page_offset(page), inode->i_ino);
404
405 ClearPageUptodate(page);
406 ClearPageMappedToDisk(page);
407
408 if (page_has_buffers(page)) {
409 struct buffer_head *bh, *head;
410 const unsigned long clear_bits =
411 (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
412 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
413 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
414
415 bh = head = page_buffers(page);
416 do {
417 lock_buffer(bh);
418 if (!silent)
419 nilfs_warn(sb,
420 "discard dirty block: blocknr=%llu, size=%zu",
421 (u64)bh->b_blocknr, bh->b_size);
422
423 set_mask_bits(&bh->b_state, clear_bits, 0);
424 unlock_buffer(bh);
425 } while (bh = bh->b_this_page, bh != head);
426 }
427
428 __nilfs_clear_page_dirty(page);
429 }
430
nilfs_page_count_clean_buffers(struct page * page,unsigned int from,unsigned int to)431 unsigned int nilfs_page_count_clean_buffers(struct page *page,
432 unsigned int from, unsigned int to)
433 {
434 unsigned int block_start, block_end;
435 struct buffer_head *bh, *head;
436 unsigned int nc = 0;
437
438 for (bh = head = page_buffers(page), block_start = 0;
439 bh != head || !block_start;
440 block_start = block_end, bh = bh->b_this_page) {
441 block_end = block_start + bh->b_size;
442 if (block_end > from && block_start < to && !buffer_dirty(bh))
443 nc++;
444 }
445 return nc;
446 }
447
448 /*
449 * NILFS2 needs clear_page_dirty() in the following two cases:
450 *
451 * 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
452 * flag of pages when it copies back pages from shadow cache to the
453 * original cache.
454 *
455 * 2) Some B-tree operations like insertion or deletion may dispose buffers
456 * in dirty state, and this needs to cancel the dirty state of their pages.
457 */
__nilfs_clear_page_dirty(struct page * page)458 int __nilfs_clear_page_dirty(struct page *page)
459 {
460 struct address_space *mapping = page->mapping;
461
462 if (mapping) {
463 xa_lock_irq(&mapping->i_pages);
464 if (test_bit(PG_dirty, &page->flags)) {
465 __xa_clear_mark(&mapping->i_pages, page_index(page),
466 PAGECACHE_TAG_DIRTY);
467 xa_unlock_irq(&mapping->i_pages);
468 return clear_page_dirty_for_io(page);
469 }
470 xa_unlock_irq(&mapping->i_pages);
471 return 0;
472 }
473 return TestClearPageDirty(page);
474 }
475
476 /**
477 * nilfs_find_uncommitted_extent - find extent of uncommitted data
478 * @inode: inode
479 * @start_blk: start block offset (in)
480 * @blkoff: start offset of the found extent (out)
481 *
482 * This function searches an extent of buffers marked "delayed" which
483 * starts from a block offset equal to or larger than @start_blk. If
484 * such an extent was found, this will store the start offset in
485 * @blkoff and return its length in blocks. Otherwise, zero is
486 * returned.
487 */
nilfs_find_uncommitted_extent(struct inode * inode,sector_t start_blk,sector_t * blkoff)488 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
489 sector_t start_blk,
490 sector_t *blkoff)
491 {
492 unsigned int i, nr_folios;
493 pgoff_t index;
494 unsigned long length = 0;
495 struct folio_batch fbatch;
496 struct folio *folio;
497
498 if (inode->i_mapping->nrpages == 0)
499 return 0;
500
501 index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
502
503 folio_batch_init(&fbatch);
504
505 repeat:
506 nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
507 &fbatch);
508 if (nr_folios == 0)
509 return length;
510
511 i = 0;
512 do {
513 folio = fbatch.folios[i];
514
515 folio_lock(folio);
516 if (folio_buffers(folio)) {
517 struct buffer_head *bh, *head;
518 sector_t b;
519
520 b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
521 bh = head = folio_buffers(folio);
522 do {
523 if (b < start_blk)
524 continue;
525 if (buffer_delay(bh)) {
526 if (length == 0)
527 *blkoff = b;
528 length++;
529 } else if (length > 0) {
530 goto out_locked;
531 }
532 } while (++b, bh = bh->b_this_page, bh != head);
533 } else {
534 if (length > 0)
535 goto out_locked;
536 }
537 folio_unlock(folio);
538
539 } while (++i < nr_folios);
540
541 folio_batch_release(&fbatch);
542 cond_resched();
543 goto repeat;
544
545 out_locked:
546 folio_unlock(folio);
547 folio_batch_release(&fbatch);
548 return length;
549 }
550