1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * page.c - 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, *sbufs;
199 unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
200
201 BUG_ON(PageWriteback(dst));
202
203 sbh = sbufs = 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 pagevec pvec;
244 unsigned int i;
245 pgoff_t index = 0;
246 int err = 0;
247
248 pagevec_init(&pvec);
249 repeat:
250 if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY))
251 return 0;
252
253 for (i = 0; i < pagevec_count(&pvec); i++) {
254 struct page *page = pvec.pages[i], *dpage;
255
256 lock_page(page);
257 if (unlikely(!PageDirty(page)))
258 NILFS_PAGE_BUG(page, "inconsistent dirty state");
259
260 dpage = grab_cache_page(dmap, page->index);
261 if (unlikely(!dpage)) {
262 /* No empty page is added to the page cache */
263 err = -ENOMEM;
264 unlock_page(page);
265 break;
266 }
267 if (unlikely(!page_has_buffers(page)))
268 NILFS_PAGE_BUG(page,
269 "found empty page in dat page cache");
270
271 nilfs_copy_page(dpage, page, 1);
272 __set_page_dirty_nobuffers(dpage);
273
274 unlock_page(dpage);
275 put_page(dpage);
276 unlock_page(page);
277 }
278 pagevec_release(&pvec);
279 cond_resched();
280
281 if (likely(!err))
282 goto repeat;
283 return err;
284 }
285
286 /**
287 * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
288 * @dmap: destination page cache
289 * @smap: source page cache
290 *
291 * No pages must be added to the cache during this process.
292 * This must be ensured by the caller.
293 */
nilfs_copy_back_pages(struct address_space * dmap,struct address_space * smap)294 void nilfs_copy_back_pages(struct address_space *dmap,
295 struct address_space *smap)
296 {
297 struct pagevec pvec;
298 unsigned int i, n;
299 pgoff_t index = 0;
300
301 pagevec_init(&pvec);
302 repeat:
303 n = pagevec_lookup(&pvec, smap, &index);
304 if (!n)
305 return;
306
307 for (i = 0; i < pagevec_count(&pvec); i++) {
308 struct page *page = pvec.pages[i], *dpage;
309 pgoff_t offset = page->index;
310
311 lock_page(page);
312 dpage = find_lock_page(dmap, offset);
313 if (dpage) {
314 /* overwrite existing page in the destination cache */
315 WARN_ON(PageDirty(dpage));
316 nilfs_copy_page(dpage, page, 0);
317 unlock_page(dpage);
318 put_page(dpage);
319 /* Do we not need to remove page from smap here? */
320 } else {
321 struct page *p;
322
323 /* move the page to the destination cache */
324 xa_lock_irq(&smap->i_pages);
325 p = __xa_erase(&smap->i_pages, offset);
326 WARN_ON(page != p);
327 smap->nrpages--;
328 xa_unlock_irq(&smap->i_pages);
329
330 xa_lock_irq(&dmap->i_pages);
331 p = __xa_store(&dmap->i_pages, offset, page, GFP_NOFS);
332 if (unlikely(p)) {
333 /* Probably -ENOMEM */
334 page->mapping = NULL;
335 put_page(page);
336 } else {
337 page->mapping = dmap;
338 dmap->nrpages++;
339 if (PageDirty(page))
340 __xa_set_mark(&dmap->i_pages, offset,
341 PAGECACHE_TAG_DIRTY);
342 }
343 xa_unlock_irq(&dmap->i_pages);
344 }
345 unlock_page(page);
346 }
347 pagevec_release(&pvec);
348 cond_resched();
349
350 goto repeat;
351 }
352
353 /**
354 * nilfs_clear_dirty_pages - discard dirty pages in address space
355 * @mapping: address space with dirty pages for discarding
356 * @silent: suppress [true] or print [false] warning messages
357 */
nilfs_clear_dirty_pages(struct address_space * mapping,bool silent)358 void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
359 {
360 struct pagevec pvec;
361 unsigned int i;
362 pgoff_t index = 0;
363
364 pagevec_init(&pvec);
365
366 while (pagevec_lookup_tag(&pvec, mapping, &index,
367 PAGECACHE_TAG_DIRTY)) {
368 for (i = 0; i < pagevec_count(&pvec); i++) {
369 struct page *page = pvec.pages[i];
370
371 lock_page(page);
372
373 /*
374 * This page may have been removed from the address
375 * space by truncation or invalidation when the lock
376 * was acquired. Skip processing in that case.
377 */
378 if (likely(page->mapping == mapping))
379 nilfs_clear_dirty_page(page, silent);
380
381 unlock_page(page);
382 }
383 pagevec_release(&pvec);
384 cond_resched();
385 }
386 }
387
388 /**
389 * nilfs_clear_dirty_page - discard dirty page
390 * @page: dirty page that will be discarded
391 * @silent: suppress [true] or print [false] warning messages
392 */
nilfs_clear_dirty_page(struct page * page,bool silent)393 void nilfs_clear_dirty_page(struct page *page, bool silent)
394 {
395 struct inode *inode = page->mapping->host;
396 struct super_block *sb = inode->i_sb;
397
398 BUG_ON(!PageLocked(page));
399
400 if (!silent)
401 nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu",
402 page_offset(page), inode->i_ino);
403
404 ClearPageUptodate(page);
405 ClearPageMappedToDisk(page);
406
407 if (page_has_buffers(page)) {
408 struct buffer_head *bh, *head;
409 const unsigned long clear_bits =
410 (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
411 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
412 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
413
414 bh = head = page_buffers(page);
415 do {
416 lock_buffer(bh);
417 if (!silent)
418 nilfs_warn(sb,
419 "discard dirty block: blocknr=%llu, size=%zu",
420 (u64)bh->b_blocknr, bh->b_size);
421
422 set_mask_bits(&bh->b_state, clear_bits, 0);
423 unlock_buffer(bh);
424 } while (bh = bh->b_this_page, bh != head);
425 }
426
427 __nilfs_clear_page_dirty(page);
428 }
429
nilfs_page_count_clean_buffers(struct page * page,unsigned int from,unsigned int to)430 unsigned int nilfs_page_count_clean_buffers(struct page *page,
431 unsigned int from, unsigned int to)
432 {
433 unsigned int block_start, block_end;
434 struct buffer_head *bh, *head;
435 unsigned int nc = 0;
436
437 for (bh = head = page_buffers(page), block_start = 0;
438 bh != head || !block_start;
439 block_start = block_end, bh = bh->b_this_page) {
440 block_end = block_start + bh->b_size;
441 if (block_end > from && block_start < to && !buffer_dirty(bh))
442 nc++;
443 }
444 return nc;
445 }
446
nilfs_mapping_init(struct address_space * mapping,struct inode * inode)447 void nilfs_mapping_init(struct address_space *mapping, struct inode *inode)
448 {
449 mapping->host = inode;
450 mapping->flags = 0;
451 mapping_set_gfp_mask(mapping, GFP_NOFS);
452 mapping->private_data = NULL;
453 mapping->a_ops = &empty_aops;
454 }
455
456 /*
457 * NILFS2 needs clear_page_dirty() in the following two cases:
458 *
459 * 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
460 * flag of pages when it copies back pages from shadow cache to the
461 * original cache.
462 *
463 * 2) Some B-tree operations like insertion or deletion may dispose buffers
464 * in dirty state, and this needs to cancel the dirty state of their pages.
465 */
__nilfs_clear_page_dirty(struct page * page)466 int __nilfs_clear_page_dirty(struct page *page)
467 {
468 struct address_space *mapping = page->mapping;
469
470 if (mapping) {
471 xa_lock_irq(&mapping->i_pages);
472 if (test_bit(PG_dirty, &page->flags)) {
473 __xa_clear_mark(&mapping->i_pages, page_index(page),
474 PAGECACHE_TAG_DIRTY);
475 xa_unlock_irq(&mapping->i_pages);
476 return clear_page_dirty_for_io(page);
477 }
478 xa_unlock_irq(&mapping->i_pages);
479 return 0;
480 }
481 return TestClearPageDirty(page);
482 }
483
484 /**
485 * nilfs_find_uncommitted_extent - find extent of uncommitted data
486 * @inode: inode
487 * @start_blk: start block offset (in)
488 * @blkoff: start offset of the found extent (out)
489 *
490 * This function searches an extent of buffers marked "delayed" which
491 * starts from a block offset equal to or larger than @start_blk. If
492 * such an extent was found, this will store the start offset in
493 * @blkoff and return its length in blocks. Otherwise, zero is
494 * returned.
495 */
nilfs_find_uncommitted_extent(struct inode * inode,sector_t start_blk,sector_t * blkoff)496 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
497 sector_t start_blk,
498 sector_t *blkoff)
499 {
500 unsigned int i;
501 pgoff_t index;
502 unsigned int nblocks_in_page;
503 unsigned long length = 0;
504 sector_t b;
505 struct pagevec pvec;
506 struct page *page;
507
508 if (inode->i_mapping->nrpages == 0)
509 return 0;
510
511 index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
512 nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits);
513
514 pagevec_init(&pvec);
515
516 repeat:
517 pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
518 pvec.pages);
519 if (pvec.nr == 0)
520 return length;
521
522 if (length > 0 && pvec.pages[0]->index > index)
523 goto out;
524
525 b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits);
526 i = 0;
527 do {
528 page = pvec.pages[i];
529
530 lock_page(page);
531 if (page_has_buffers(page)) {
532 struct buffer_head *bh, *head;
533
534 bh = head = page_buffers(page);
535 do {
536 if (b < start_blk)
537 continue;
538 if (buffer_delay(bh)) {
539 if (length == 0)
540 *blkoff = b;
541 length++;
542 } else if (length > 0) {
543 goto out_locked;
544 }
545 } while (++b, bh = bh->b_this_page, bh != head);
546 } else {
547 if (length > 0)
548 goto out_locked;
549
550 b += nblocks_in_page;
551 }
552 unlock_page(page);
553
554 } while (++i < pagevec_count(&pvec));
555
556 index = page->index + 1;
557 pagevec_release(&pvec);
558 cond_resched();
559 goto repeat;
560
561 out_locked:
562 unlock_page(page);
563 out:
564 pagevec_release(&pvec);
565 return length;
566 }
567