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_folio_block(struct folio *folio,
29 unsigned long block, pgoff_t index, int blkbits,
30 unsigned long b_state)
31
32 {
33 unsigned long first_block;
34 struct buffer_head *bh = folio_buffers(folio);
35
36 if (!bh)
37 bh = create_empty_buffers(folio, 1 << blkbits, b_state);
38
39 first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
40 bh = get_nth_bh(bh, block - first_block);
41
42 touch_buffer(bh);
43 wait_on_buffer(bh);
44 return bh;
45 }
46
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 folio *folio;
55 struct buffer_head *bh;
56
57 folio = filemap_grab_folio(mapping, index);
58 if (IS_ERR(folio))
59 return NULL;
60
61 bh = __nilfs_get_folio_block(folio, blkoff, index, blkbits, b_state);
62 if (unlikely(!bh)) {
63 folio_unlock(folio);
64 folio_put(folio);
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 */
74 void nilfs_forget_buffer(struct buffer_head *bh)
75 {
76 struct folio *folio = bh->b_folio;
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_folio_buffers_clean(folio))
85 __nilfs_clear_folio_dirty(folio);
86
87 bh->b_blocknr = -1;
88 folio_clear_uptodate(folio);
89 folio_clear_mappedtodisk(folio);
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 */
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_local_page(spage);
107 kaddr1 = kmap_local_page(dpage);
108 memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
109 kunmap_local(kaddr1);
110 kunmap_local(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_folio_buffers_clean - Check if a folio has dirty buffers or not.
135 * @folio: Folio to be checked.
136 *
137 * nilfs_folio_buffers_clean() returns false if the folio has dirty buffers.
138 * Otherwise, it returns true.
139 */
140 bool nilfs_folio_buffers_clean(struct folio *folio)
141 {
142 struct buffer_head *bh, *head;
143
144 bh = head = folio_buffers(folio);
145 do {
146 if (buffer_dirty(bh))
147 return false;
148 bh = bh->b_this_page;
149 } while (bh != head);
150 return true;
151 }
152
153 void nilfs_folio_bug(struct folio *folio)
154 {
155 struct buffer_head *bh, *head;
156 struct address_space *m;
157 unsigned long ino;
158
159 if (unlikely(!folio)) {
160 printk(KERN_CRIT "NILFS_FOLIO_BUG(NULL)\n");
161 return;
162 }
163
164 m = folio->mapping;
165 ino = m ? m->host->i_ino : 0;
166
167 printk(KERN_CRIT "NILFS_FOLIO_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
168 "mapping=%p ino=%lu\n",
169 folio, folio_ref_count(folio),
170 (unsigned long long)folio->index, folio->flags, m, ino);
171
172 head = folio_buffers(folio);
173 if (head) {
174 int i = 0;
175
176 bh = head;
177 do {
178 printk(KERN_CRIT
179 " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
180 i++, bh, atomic_read(&bh->b_count),
181 (unsigned long long)bh->b_blocknr, bh->b_state);
182 bh = bh->b_this_page;
183 } while (bh != head);
184 }
185 }
186
187 /**
188 * nilfs_copy_folio -- copy the folio with buffers
189 * @dst: destination folio
190 * @src: source folio
191 * @copy_dirty: flag whether to copy dirty states on the folio's buffer heads.
192 *
193 * This function is for both data folios and btnode folios. The dirty flag
194 * should be treated by caller. The folio must not be under i/o.
195 * Both src and dst folio must be locked
196 */
197 static void nilfs_copy_folio(struct folio *dst, struct folio *src,
198 bool copy_dirty)
199 {
200 struct buffer_head *dbh, *dbufs, *sbh;
201 unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
202
203 BUG_ON(folio_test_writeback(dst));
204
205 sbh = folio_buffers(src);
206 dbh = folio_buffers(dst);
207 if (!dbh)
208 dbh = create_empty_buffers(dst, sbh->b_size, 0);
209
210 if (copy_dirty)
211 mask |= BIT(BH_Dirty);
212
213 dbufs = dbh;
214 do {
215 lock_buffer(sbh);
216 lock_buffer(dbh);
217 dbh->b_state = sbh->b_state & mask;
218 dbh->b_blocknr = sbh->b_blocknr;
219 dbh->b_bdev = sbh->b_bdev;
220 sbh = sbh->b_this_page;
221 dbh = dbh->b_this_page;
222 } while (dbh != dbufs);
223
224 folio_copy(dst, src);
225
226 if (folio_test_uptodate(src) && !folio_test_uptodate(dst))
227 folio_mark_uptodate(dst);
228 else if (!folio_test_uptodate(src) && folio_test_uptodate(dst))
229 folio_clear_uptodate(dst);
230 if (folio_test_mappedtodisk(src) && !folio_test_mappedtodisk(dst))
231 folio_set_mappedtodisk(dst);
232 else if (!folio_test_mappedtodisk(src) && folio_test_mappedtodisk(dst))
233 folio_clear_mappedtodisk(dst);
234
235 do {
236 unlock_buffer(sbh);
237 unlock_buffer(dbh);
238 sbh = sbh->b_this_page;
239 dbh = dbh->b_this_page;
240 } while (dbh != dbufs);
241 }
242
243 int nilfs_copy_dirty_pages(struct address_space *dmap,
244 struct address_space *smap)
245 {
246 struct folio_batch fbatch;
247 unsigned int i;
248 pgoff_t index = 0;
249 int err = 0;
250
251 folio_batch_init(&fbatch);
252 repeat:
253 if (!filemap_get_folios_tag(smap, &index, (pgoff_t)-1,
254 PAGECACHE_TAG_DIRTY, &fbatch))
255 return 0;
256
257 for (i = 0; i < folio_batch_count(&fbatch); i++) {
258 struct folio *folio = fbatch.folios[i], *dfolio;
259
260 folio_lock(folio);
261 if (unlikely(!folio_test_dirty(folio)))
262 NILFS_FOLIO_BUG(folio, "inconsistent dirty state");
263
264 dfolio = filemap_grab_folio(dmap, folio->index);
265 if (unlikely(IS_ERR(dfolio))) {
266 /* No empty page is added to the page cache */
267 folio_unlock(folio);
268 err = PTR_ERR(dfolio);
269 break;
270 }
271 if (unlikely(!folio_buffers(folio)))
272 NILFS_FOLIO_BUG(folio,
273 "found empty page in dat page cache");
274
275 nilfs_copy_folio(dfolio, folio, true);
276 filemap_dirty_folio(folio_mapping(dfolio), dfolio);
277
278 folio_unlock(dfolio);
279 folio_put(dfolio);
280 folio_unlock(folio);
281 }
282 folio_batch_release(&fbatch);
283 cond_resched();
284
285 if (likely(!err))
286 goto repeat;
287 return err;
288 }
289
290 /**
291 * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
292 * @dmap: destination page cache
293 * @smap: source page cache
294 *
295 * No pages must be added to the cache during this process.
296 * This must be ensured by the caller.
297 */
298 void nilfs_copy_back_pages(struct address_space *dmap,
299 struct address_space *smap)
300 {
301 struct folio_batch fbatch;
302 unsigned int i, n;
303 pgoff_t start = 0;
304
305 folio_batch_init(&fbatch);
306 repeat:
307 n = filemap_get_folios(smap, &start, ~0UL, &fbatch);
308 if (!n)
309 return;
310
311 for (i = 0; i < folio_batch_count(&fbatch); i++) {
312 struct folio *folio = fbatch.folios[i], *dfolio;
313 pgoff_t index = folio->index;
314
315 folio_lock(folio);
316 dfolio = filemap_lock_folio(dmap, index);
317 if (!IS_ERR(dfolio)) {
318 /* overwrite existing folio in the destination cache */
319 WARN_ON(folio_test_dirty(dfolio));
320 nilfs_copy_folio(dfolio, folio, false);
321 folio_unlock(dfolio);
322 folio_put(dfolio);
323 /* Do we not need to remove folio from smap here? */
324 } else {
325 struct folio *f;
326
327 /* move the folio to the destination cache */
328 xa_lock_irq(&smap->i_pages);
329 f = __xa_erase(&smap->i_pages, index);
330 WARN_ON(folio != f);
331 smap->nrpages--;
332 xa_unlock_irq(&smap->i_pages);
333
334 xa_lock_irq(&dmap->i_pages);
335 f = __xa_store(&dmap->i_pages, index, folio, GFP_NOFS);
336 if (unlikely(f)) {
337 /* Probably -ENOMEM */
338 folio->mapping = NULL;
339 folio_put(folio);
340 } else {
341 folio->mapping = dmap;
342 dmap->nrpages++;
343 if (folio_test_dirty(folio))
344 __xa_set_mark(&dmap->i_pages, index,
345 PAGECACHE_TAG_DIRTY);
346 }
347 xa_unlock_irq(&dmap->i_pages);
348 }
349 folio_unlock(folio);
350 }
351 folio_batch_release(&fbatch);
352 cond_resched();
353
354 goto repeat;
355 }
356
357 /**
358 * nilfs_clear_dirty_pages - discard dirty pages in address space
359 * @mapping: address space with dirty pages for discarding
360 * @silent: suppress [true] or print [false] warning messages
361 */
362 void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
363 {
364 struct folio_batch fbatch;
365 unsigned int i;
366 pgoff_t index = 0;
367
368 folio_batch_init(&fbatch);
369
370 while (filemap_get_folios_tag(mapping, &index, (pgoff_t)-1,
371 PAGECACHE_TAG_DIRTY, &fbatch)) {
372 for (i = 0; i < folio_batch_count(&fbatch); i++) {
373 struct folio *folio = fbatch.folios[i];
374
375 folio_lock(folio);
376
377 /*
378 * This folio may have been removed from the address
379 * space by truncation or invalidation when the lock
380 * was acquired. Skip processing in that case.
381 */
382 if (likely(folio->mapping == mapping))
383 nilfs_clear_folio_dirty(folio, silent);
384
385 folio_unlock(folio);
386 }
387 folio_batch_release(&fbatch);
388 cond_resched();
389 }
390 }
391
392 /**
393 * nilfs_clear_folio_dirty - discard dirty folio
394 * @folio: dirty folio that will be discarded
395 * @silent: suppress [true] or print [false] warning messages
396 */
397 void nilfs_clear_folio_dirty(struct folio *folio, bool silent)
398 {
399 struct inode *inode = folio->mapping->host;
400 struct super_block *sb = inode->i_sb;
401 struct buffer_head *bh, *head;
402
403 BUG_ON(!folio_test_locked(folio));
404
405 if (!silent)
406 nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu",
407 folio_pos(folio), inode->i_ino);
408
409 folio_clear_uptodate(folio);
410 folio_clear_mappedtodisk(folio);
411
412 head = folio_buffers(folio);
413 if (head) {
414 const unsigned long clear_bits =
415 (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
416 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
417 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
418
419 bh = head;
420 do {
421 lock_buffer(bh);
422 if (!silent)
423 nilfs_warn(sb,
424 "discard dirty block: blocknr=%llu, size=%zu",
425 (u64)bh->b_blocknr, bh->b_size);
426
427 set_mask_bits(&bh->b_state, clear_bits, 0);
428 unlock_buffer(bh);
429 } while (bh = bh->b_this_page, bh != head);
430 }
431
432 __nilfs_clear_folio_dirty(folio);
433 }
434
435 unsigned int nilfs_page_count_clean_buffers(struct page *page,
436 unsigned int from, unsigned int to)
437 {
438 unsigned int block_start, block_end;
439 struct buffer_head *bh, *head;
440 unsigned int nc = 0;
441
442 for (bh = head = page_buffers(page), block_start = 0;
443 bh != head || !block_start;
444 block_start = block_end, bh = bh->b_this_page) {
445 block_end = block_start + bh->b_size;
446 if (block_end > from && block_start < to && !buffer_dirty(bh))
447 nc++;
448 }
449 return nc;
450 }
451
452 /*
453 * NILFS2 needs clear_page_dirty() in the following two cases:
454 *
455 * 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
456 * flag of pages when it copies back pages from shadow cache to the
457 * original cache.
458 *
459 * 2) Some B-tree operations like insertion or deletion may dispose buffers
460 * in dirty state, and this needs to cancel the dirty state of their pages.
461 */
462 void __nilfs_clear_folio_dirty(struct folio *folio)
463 {
464 struct address_space *mapping = folio->mapping;
465
466 if (mapping) {
467 xa_lock_irq(&mapping->i_pages);
468 if (folio_test_dirty(folio)) {
469 __xa_clear_mark(&mapping->i_pages, folio->index,
470 PAGECACHE_TAG_DIRTY);
471 xa_unlock_irq(&mapping->i_pages);
472 folio_clear_dirty_for_io(folio);
473 return;
474 }
475 xa_unlock_irq(&mapping->i_pages);
476 return;
477 }
478 folio_clear_dirty(folio);
479 }
480
481 /**
482 * nilfs_find_uncommitted_extent - find extent of uncommitted data
483 * @inode: inode
484 * @start_blk: start block offset (in)
485 * @blkoff: start offset of the found extent (out)
486 *
487 * This function searches an extent of buffers marked "delayed" which
488 * starts from a block offset equal to or larger than @start_blk. If
489 * such an extent was found, this will store the start offset in
490 * @blkoff and return its length in blocks. Otherwise, zero is
491 * returned.
492 */
493 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
494 sector_t start_blk,
495 sector_t *blkoff)
496 {
497 unsigned int i, nr_folios;
498 pgoff_t index;
499 unsigned long length = 0;
500 struct folio_batch fbatch;
501 struct folio *folio;
502
503 if (inode->i_mapping->nrpages == 0)
504 return 0;
505
506 index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
507
508 folio_batch_init(&fbatch);
509
510 repeat:
511 nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
512 &fbatch);
513 if (nr_folios == 0)
514 return length;
515
516 i = 0;
517 do {
518 folio = fbatch.folios[i];
519
520 folio_lock(folio);
521 if (folio_buffers(folio)) {
522 struct buffer_head *bh, *head;
523 sector_t b;
524
525 b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
526 bh = head = folio_buffers(folio);
527 do {
528 if (b < start_blk)
529 continue;
530 if (buffer_delay(bh)) {
531 if (length == 0)
532 *blkoff = b;
533 length++;
534 } else if (length > 0) {
535 goto out_locked;
536 }
537 } while (++b, bh = bh->b_this_page, bh != head);
538 } else {
539 if (length > 0)
540 goto out_locked;
541 }
542 folio_unlock(folio);
543
544 } while (++i < nr_folios);
545
546 folio_batch_release(&fbatch);
547 cond_resched();
548 goto repeat;
549
550 out_locked:
551 folio_unlock(folio);
552 folio_batch_release(&fbatch);
553 return length;
554 }
555
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