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
__nilfs_get_folio_block(struct folio * folio,unsigned long block,pgoff_t index,int blkbits,unsigned long b_state)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
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 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 */
nilfs_forget_buffer(struct buffer_head * bh)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 BIT(BH_Delay));
82
83 lock_buffer(bh);
84 set_mask_bits(&bh->b_state, clear_bits, 0);
85 if (nilfs_folio_buffers_clean(folio))
86 __nilfs_clear_folio_dirty(folio);
87
88 bh->b_blocknr = -1;
89 folio_clear_uptodate(folio);
90 folio_clear_mappedtodisk(folio);
91 unlock_buffer(bh);
92 brelse(bh);
93 }
94
95 /**
96 * nilfs_copy_buffer -- copy buffer data and flags
97 * @dbh: destination buffer
98 * @sbh: source buffer
99 */
nilfs_copy_buffer(struct buffer_head * dbh,struct buffer_head * sbh)100 void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
101 {
102 void *kaddr0, *kaddr1;
103 unsigned long bits;
104 struct page *spage = sbh->b_page, *dpage = dbh->b_page;
105 struct buffer_head *bh;
106
107 kaddr0 = kmap_local_page(spage);
108 kaddr1 = kmap_local_page(dpage);
109 memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
110 kunmap_local(kaddr1);
111 kunmap_local(kaddr0);
112
113 dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
114 dbh->b_blocknr = sbh->b_blocknr;
115 dbh->b_bdev = sbh->b_bdev;
116
117 bh = dbh;
118 bits = sbh->b_state & (BIT(BH_Uptodate) | BIT(BH_Mapped));
119 while ((bh = bh->b_this_page) != dbh) {
120 lock_buffer(bh);
121 bits &= bh->b_state;
122 unlock_buffer(bh);
123 }
124 if (bits & BIT(BH_Uptodate))
125 SetPageUptodate(dpage);
126 else
127 ClearPageUptodate(dpage);
128 if (bits & BIT(BH_Mapped))
129 SetPageMappedToDisk(dpage);
130 else
131 ClearPageMappedToDisk(dpage);
132 }
133
134 /**
135 * nilfs_folio_buffers_clean - Check if a folio has dirty buffers or not.
136 * @folio: Folio to be checked.
137 *
138 * nilfs_folio_buffers_clean() returns false if the folio has dirty buffers.
139 * Otherwise, it returns true.
140 */
nilfs_folio_buffers_clean(struct folio * folio)141 bool nilfs_folio_buffers_clean(struct folio *folio)
142 {
143 struct buffer_head *bh, *head;
144
145 bh = head = folio_buffers(folio);
146 do {
147 if (buffer_dirty(bh))
148 return false;
149 bh = bh->b_this_page;
150 } while (bh != head);
151 return true;
152 }
153
nilfs_folio_bug(struct folio * folio)154 void nilfs_folio_bug(struct folio *folio)
155 {
156 struct buffer_head *bh, *head;
157 struct address_space *m;
158 unsigned long ino;
159
160 if (unlikely(!folio)) {
161 printk(KERN_CRIT "NILFS_FOLIO_BUG(NULL)\n");
162 return;
163 }
164
165 m = folio->mapping;
166 ino = m ? m->host->i_ino : 0;
167
168 printk(KERN_CRIT "NILFS_FOLIO_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
169 "mapping=%p ino=%lu\n",
170 folio, folio_ref_count(folio),
171 (unsigned long long)folio->index, folio->flags, m, ino);
172
173 head = folio_buffers(folio);
174 if (head) {
175 int i = 0;
176
177 bh = head;
178 do {
179 printk(KERN_CRIT
180 " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
181 i++, bh, atomic_read(&bh->b_count),
182 (unsigned long long)bh->b_blocknr, bh->b_state);
183 bh = bh->b_this_page;
184 } while (bh != head);
185 }
186 }
187
188 /**
189 * nilfs_copy_folio -- copy the folio with buffers
190 * @dst: destination folio
191 * @src: source folio
192 * @copy_dirty: flag whether to copy dirty states on the folio's buffer heads.
193 *
194 * This function is for both data folios and btnode folios. The dirty flag
195 * should be treated by caller. The folio must not be under i/o.
196 * Both src and dst folio must be locked
197 */
nilfs_copy_folio(struct folio * dst,struct folio * src,bool copy_dirty)198 static void nilfs_copy_folio(struct folio *dst, struct folio *src,
199 bool copy_dirty)
200 {
201 struct buffer_head *dbh, *dbufs, *sbh;
202 unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
203
204 BUG_ON(folio_test_writeback(dst));
205
206 sbh = folio_buffers(src);
207 dbh = folio_buffers(dst);
208 if (!dbh)
209 dbh = create_empty_buffers(dst, sbh->b_size, 0);
210
211 if (copy_dirty)
212 mask |= BIT(BH_Dirty);
213
214 dbufs = dbh;
215 do {
216 lock_buffer(sbh);
217 lock_buffer(dbh);
218 dbh->b_state = sbh->b_state & mask;
219 dbh->b_blocknr = sbh->b_blocknr;
220 dbh->b_bdev = sbh->b_bdev;
221 sbh = sbh->b_this_page;
222 dbh = dbh->b_this_page;
223 } while (dbh != dbufs);
224
225 folio_copy(dst, src);
226
227 if (folio_test_uptodate(src) && !folio_test_uptodate(dst))
228 folio_mark_uptodate(dst);
229 else if (!folio_test_uptodate(src) && folio_test_uptodate(dst))
230 folio_clear_uptodate(dst);
231 if (folio_test_mappedtodisk(src) && !folio_test_mappedtodisk(dst))
232 folio_set_mappedtodisk(dst);
233 else if (!folio_test_mappedtodisk(src) && folio_test_mappedtodisk(dst))
234 folio_clear_mappedtodisk(dst);
235
236 do {
237 unlock_buffer(sbh);
238 unlock_buffer(dbh);
239 sbh = sbh->b_this_page;
240 dbh = dbh->b_this_page;
241 } while (dbh != dbufs);
242 }
243
nilfs_copy_dirty_pages(struct address_space * dmap,struct address_space * smap)244 int nilfs_copy_dirty_pages(struct address_space *dmap,
245 struct address_space *smap)
246 {
247 struct folio_batch fbatch;
248 unsigned int i;
249 pgoff_t index = 0;
250 int err = 0;
251
252 folio_batch_init(&fbatch);
253 repeat:
254 if (!filemap_get_folios_tag(smap, &index, (pgoff_t)-1,
255 PAGECACHE_TAG_DIRTY, &fbatch))
256 return 0;
257
258 for (i = 0; i < folio_batch_count(&fbatch); i++) {
259 struct folio *folio = fbatch.folios[i], *dfolio;
260
261 folio_lock(folio);
262 if (unlikely(!folio_test_dirty(folio)))
263 NILFS_FOLIO_BUG(folio, "inconsistent dirty state");
264
265 dfolio = filemap_grab_folio(dmap, folio->index);
266 if (IS_ERR(dfolio)) {
267 /* No empty page is added to the page cache */
268 folio_unlock(folio);
269 err = PTR_ERR(dfolio);
270 break;
271 }
272 if (unlikely(!folio_buffers(folio)))
273 NILFS_FOLIO_BUG(folio,
274 "found empty page in dat page cache");
275
276 nilfs_copy_folio(dfolio, folio, true);
277 filemap_dirty_folio(folio_mapping(dfolio), dfolio);
278
279 folio_unlock(dfolio);
280 folio_put(dfolio);
281 folio_unlock(folio);
282 }
283 folio_batch_release(&fbatch);
284 cond_resched();
285
286 if (likely(!err))
287 goto repeat;
288 return err;
289 }
290
291 /**
292 * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
293 * @dmap: destination page cache
294 * @smap: source page cache
295 *
296 * No pages must be added to the cache during this process.
297 * This must be ensured by the caller.
298 */
nilfs_copy_back_pages(struct address_space * dmap,struct address_space * smap)299 void nilfs_copy_back_pages(struct address_space *dmap,
300 struct address_space *smap)
301 {
302 struct folio_batch fbatch;
303 unsigned int i, n;
304 pgoff_t start = 0;
305
306 folio_batch_init(&fbatch);
307 repeat:
308 n = filemap_get_folios(smap, &start, ~0UL, &fbatch);
309 if (!n)
310 return;
311
312 for (i = 0; i < folio_batch_count(&fbatch); i++) {
313 struct folio *folio = fbatch.folios[i], *dfolio;
314 pgoff_t index = folio->index;
315
316 folio_lock(folio);
317 dfolio = filemap_lock_folio(dmap, index);
318 if (!IS_ERR(dfolio)) {
319 /* overwrite existing folio in the destination cache */
320 WARN_ON(folio_test_dirty(dfolio));
321 nilfs_copy_folio(dfolio, folio, false);
322 folio_unlock(dfolio);
323 folio_put(dfolio);
324 /* Do we not need to remove folio from smap here? */
325 } else {
326 struct folio *f;
327
328 /* move the folio to the destination cache */
329 xa_lock_irq(&smap->i_pages);
330 f = __xa_erase(&smap->i_pages, index);
331 WARN_ON(folio != f);
332 smap->nrpages--;
333 xa_unlock_irq(&smap->i_pages);
334
335 xa_lock_irq(&dmap->i_pages);
336 f = __xa_store(&dmap->i_pages, index, folio, GFP_NOFS);
337 if (unlikely(f)) {
338 /* Probably -ENOMEM */
339 folio->mapping = NULL;
340 folio_put(folio);
341 } else {
342 folio->mapping = dmap;
343 dmap->nrpages++;
344 if (folio_test_dirty(folio))
345 __xa_set_mark(&dmap->i_pages, index,
346 PAGECACHE_TAG_DIRTY);
347 }
348 xa_unlock_irq(&dmap->i_pages);
349 }
350 folio_unlock(folio);
351 }
352 folio_batch_release(&fbatch);
353 cond_resched();
354
355 goto repeat;
356 }
357
358 /**
359 * nilfs_clear_dirty_pages - discard dirty pages in address space
360 * @mapping: address space with dirty pages for discarding
361 */
nilfs_clear_dirty_pages(struct address_space * mapping)362 void nilfs_clear_dirty_pages(struct address_space *mapping)
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);
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 */
nilfs_clear_folio_dirty(struct folio * folio)396 void nilfs_clear_folio_dirty(struct folio *folio)
397 {
398 struct buffer_head *bh, *head;
399
400 BUG_ON(!folio_test_locked(folio));
401
402 folio_clear_uptodate(folio);
403 folio_clear_mappedtodisk(folio);
404 folio_clear_checked(folio);
405
406 head = folio_buffers(folio);
407 if (head) {
408 const unsigned long clear_bits =
409 (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
410 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
411 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) |
412 BIT(BH_Delay));
413
414 bh = head;
415 do {
416 lock_buffer(bh);
417 set_mask_bits(&bh->b_state, clear_bits, 0);
418 unlock_buffer(bh);
419 } while (bh = bh->b_this_page, bh != head);
420 }
421
422 __nilfs_clear_folio_dirty(folio);
423 }
424
nilfs_page_count_clean_buffers(struct page * page,unsigned int from,unsigned int to)425 unsigned int nilfs_page_count_clean_buffers(struct page *page,
426 unsigned int from, unsigned int to)
427 {
428 unsigned int block_start, block_end;
429 struct buffer_head *bh, *head;
430 unsigned int nc = 0;
431
432 for (bh = head = page_buffers(page), block_start = 0;
433 bh != head || !block_start;
434 block_start = block_end, bh = bh->b_this_page) {
435 block_end = block_start + bh->b_size;
436 if (block_end > from && block_start < to && !buffer_dirty(bh))
437 nc++;
438 }
439 return nc;
440 }
441
442 /*
443 * NILFS2 needs clear_page_dirty() in the following two cases:
444 *
445 * 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
446 * flag of pages when it copies back pages from shadow cache to the
447 * original cache.
448 *
449 * 2) Some B-tree operations like insertion or deletion may dispose buffers
450 * in dirty state, and this needs to cancel the dirty state of their pages.
451 */
__nilfs_clear_folio_dirty(struct folio * folio)452 void __nilfs_clear_folio_dirty(struct folio *folio)
453 {
454 struct address_space *mapping = folio->mapping;
455
456 if (mapping) {
457 xa_lock_irq(&mapping->i_pages);
458 if (folio_test_dirty(folio)) {
459 __xa_clear_mark(&mapping->i_pages, folio->index,
460 PAGECACHE_TAG_DIRTY);
461 xa_unlock_irq(&mapping->i_pages);
462 folio_clear_dirty_for_io(folio);
463 return;
464 }
465 xa_unlock_irq(&mapping->i_pages);
466 return;
467 }
468 folio_clear_dirty(folio);
469 }
470
471 /**
472 * nilfs_find_uncommitted_extent - find extent of uncommitted data
473 * @inode: inode
474 * @start_blk: start block offset (in)
475 * @blkoff: start offset of the found extent (out)
476 *
477 * This function searches an extent of buffers marked "delayed" which
478 * starts from a block offset equal to or larger than @start_blk. If
479 * such an extent was found, this will store the start offset in
480 * @blkoff and return its length in blocks. Otherwise, zero is
481 * returned.
482 */
nilfs_find_uncommitted_extent(struct inode * inode,sector_t start_blk,sector_t * blkoff)483 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
484 sector_t start_blk,
485 sector_t *blkoff)
486 {
487 unsigned int i, nr_folios;
488 pgoff_t index;
489 unsigned long length = 0;
490 struct folio_batch fbatch;
491 struct folio *folio;
492
493 if (inode->i_mapping->nrpages == 0)
494 return 0;
495
496 index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
497
498 folio_batch_init(&fbatch);
499
500 repeat:
501 nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
502 &fbatch);
503 if (nr_folios == 0)
504 return length;
505
506 i = 0;
507 do {
508 folio = fbatch.folios[i];
509
510 folio_lock(folio);
511 if (folio_buffers(folio)) {
512 struct buffer_head *bh, *head;
513 sector_t b;
514
515 b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
516 bh = head = folio_buffers(folio);
517 do {
518 if (b < start_blk)
519 continue;
520 if (buffer_delay(bh)) {
521 if (length == 0)
522 *blkoff = b;
523 length++;
524 } else if (length > 0) {
525 goto out_locked;
526 }
527 } while (++b, bh = bh->b_this_page, bh != head);
528 } else {
529 if (length > 0)
530 goto out_locked;
531 }
532 folio_unlock(folio);
533
534 } while (++i < nr_folios);
535
536 folio_batch_release(&fbatch);
537 cond_resched();
538 goto repeat;
539
540 out_locked:
541 folio_unlock(folio);
542 folio_batch_release(&fbatch);
543 return length;
544 }
545