xref: /linux/fs/nilfs2/page.c (revision f5f4745a7f057b58c9728ee4e2c5d6d79f382fe7)
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 	wait_on_buffer(bh);
43 	return bh;
44 }
45 
nilfs_grab_buffer(struct inode * inode,struct address_space * mapping,unsigned long blkoff,unsigned long b_state)46 struct buffer_head *nilfs_grab_buffer(struct inode *inode,
47 				      struct address_space *mapping,
48 				      unsigned long blkoff,
49 				      unsigned long b_state)
50 {
51 	int blkbits = inode->i_blkbits;
52 	pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
53 	struct folio *folio;
54 	struct buffer_head *bh;
55 
56 	folio = filemap_grab_folio(mapping, index);
57 	if (IS_ERR(folio))
58 		return NULL;
59 
60 	bh = __nilfs_get_folio_block(folio, blkoff, index, blkbits, b_state);
61 	if (unlikely(!bh)) {
62 		folio_unlock(folio);
63 		folio_put(folio);
64 		return NULL;
65 	}
66 	bh->b_bdev = inode->i_sb->s_bdev;
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 *saddr, *daddr;
103 	unsigned long bits;
104 	struct folio *sfolio = sbh->b_folio, *dfolio = dbh->b_folio;
105 	struct buffer_head *bh;
106 
107 	saddr = kmap_local_folio(sfolio, bh_offset(sbh));
108 	daddr = kmap_local_folio(dfolio, bh_offset(dbh));
109 	memcpy(daddr, saddr, sbh->b_size);
110 	kunmap_local(daddr);
111 	kunmap_local(saddr);
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 		folio_mark_uptodate(dfolio);
126 	else
127 		folio_clear_uptodate(dfolio);
128 	if (bits & BIT(BH_Mapped))
129 		folio_set_mappedtodisk(dfolio);
130 	else
131 		folio_clear_mappedtodisk(dfolio);
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 folio * folio,unsigned int from,unsigned int to)425 unsigned int nilfs_page_count_clean_buffers(struct folio *folio,
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 = folio_buffers(folio), 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