xref: /openbmc/linux/fs/nilfs2/page.c (revision 83b975b5) 
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 *
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 
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  */
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  */
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  */
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 
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  */
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 
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  */
294 void nilfs_copy_back_pages(struct address_space *dmap,
295 			   struct address_space *smap)
296 {
297 	struct folio_batch fbatch;
298 	unsigned int i, n;
299 	pgoff_t start = 0;
300 
301 	folio_batch_init(&fbatch);
302 repeat:
303 	n = filemap_get_folios(smap, &start, ~0UL, &fbatch);
304 	if (!n)
305 		return;
306 
307 	for (i = 0; i < folio_batch_count(&fbatch); i++) {
308 		struct folio *folio = fbatch.folios[i], *dfolio;
309 		pgoff_t index = folio->index;
310 
311 		folio_lock(folio);
312 		dfolio = filemap_lock_folio(dmap, index);
313 		if (dfolio) {
314 			/* overwrite existing folio in the destination cache */
315 			WARN_ON(folio_test_dirty(dfolio));
316 			nilfs_copy_page(&dfolio->page, &folio->page, 0);
317 			folio_unlock(dfolio);
318 			folio_put(dfolio);
319 			/* Do we not need to remove folio from smap here? */
320 		} else {
321 			struct folio *f;
322 
323 			/* move the folio to the destination cache */
324 			xa_lock_irq(&smap->i_pages);
325 			f = __xa_erase(&smap->i_pages, index);
326 			WARN_ON(folio != f);
327 			smap->nrpages--;
328 			xa_unlock_irq(&smap->i_pages);
329 
330 			xa_lock_irq(&dmap->i_pages);
331 			f = __xa_store(&dmap->i_pages, index, folio, GFP_NOFS);
332 			if (unlikely(f)) {
333 				/* Probably -ENOMEM */
334 				folio->mapping = NULL;
335 				folio_put(folio);
336 			} else {
337 				folio->mapping = dmap;
338 				dmap->nrpages++;
339 				if (folio_test_dirty(folio))
340 					__xa_set_mark(&dmap->i_pages, index,
341 							PAGECACHE_TAG_DIRTY);
342 			}
343 			xa_unlock_irq(&dmap->i_pages);
344 		}
345 		folio_unlock(folio);
346 	}
347 	folio_batch_release(&fbatch);
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  */
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 			nilfs_clear_dirty_page(page, silent);
373 			unlock_page(page);
374 		}
375 		pagevec_release(&pvec);
376 		cond_resched();
377 	}
378 }
379 
380 /**
381  * nilfs_clear_dirty_page - discard dirty page
382  * @page: dirty page that will be discarded
383  * @silent: suppress [true] or print [false] warning messages
384  */
385 void nilfs_clear_dirty_page(struct page *page, bool silent)
386 {
387 	struct inode *inode = page->mapping->host;
388 	struct super_block *sb = inode->i_sb;
389 
390 	BUG_ON(!PageLocked(page));
391 
392 	if (!silent)
393 		nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu",
394 			   page_offset(page), inode->i_ino);
395 
396 	ClearPageUptodate(page);
397 	ClearPageMappedToDisk(page);
398 
399 	if (page_has_buffers(page)) {
400 		struct buffer_head *bh, *head;
401 		const unsigned long clear_bits =
402 			(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
403 			 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
404 			 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
405 
406 		bh = head = page_buffers(page);
407 		do {
408 			lock_buffer(bh);
409 			if (!silent)
410 				nilfs_warn(sb,
411 					   "discard dirty block: blocknr=%llu, size=%zu",
412 					   (u64)bh->b_blocknr, bh->b_size);
413 
414 			set_mask_bits(&bh->b_state, clear_bits, 0);
415 			unlock_buffer(bh);
416 		} while (bh = bh->b_this_page, bh != head);
417 	}
418 
419 	__nilfs_clear_page_dirty(page);
420 }
421 
422 unsigned int nilfs_page_count_clean_buffers(struct page *page,
423 					    unsigned int from, unsigned int to)
424 {
425 	unsigned int block_start, block_end;
426 	struct buffer_head *bh, *head;
427 	unsigned int nc = 0;
428 
429 	for (bh = head = page_buffers(page), block_start = 0;
430 	     bh != head || !block_start;
431 	     block_start = block_end, bh = bh->b_this_page) {
432 		block_end = block_start + bh->b_size;
433 		if (block_end > from && block_start < to && !buffer_dirty(bh))
434 			nc++;
435 	}
436 	return nc;
437 }
438 
439 /*
440  * NILFS2 needs clear_page_dirty() in the following two cases:
441  *
442  * 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
443  *    flag of pages when it copies back pages from shadow cache to the
444  *    original cache.
445  *
446  * 2) Some B-tree operations like insertion or deletion may dispose buffers
447  *    in dirty state, and this needs to cancel the dirty state of their pages.
448  */
449 int __nilfs_clear_page_dirty(struct page *page)
450 {
451 	struct address_space *mapping = page->mapping;
452 
453 	if (mapping) {
454 		xa_lock_irq(&mapping->i_pages);
455 		if (test_bit(PG_dirty, &page->flags)) {
456 			__xa_clear_mark(&mapping->i_pages, page_index(page),
457 					     PAGECACHE_TAG_DIRTY);
458 			xa_unlock_irq(&mapping->i_pages);
459 			return clear_page_dirty_for_io(page);
460 		}
461 		xa_unlock_irq(&mapping->i_pages);
462 		return 0;
463 	}
464 	return TestClearPageDirty(page);
465 }
466 
467 /**
468  * nilfs_find_uncommitted_extent - find extent of uncommitted data
469  * @inode: inode
470  * @start_blk: start block offset (in)
471  * @blkoff: start offset of the found extent (out)
472  *
473  * This function searches an extent of buffers marked "delayed" which
474  * starts from a block offset equal to or larger than @start_blk.  If
475  * such an extent was found, this will store the start offset in
476  * @blkoff and return its length in blocks.  Otherwise, zero is
477  * returned.
478  */
479 unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
480 					    sector_t start_blk,
481 					    sector_t *blkoff)
482 {
483 	unsigned int i, nr_folios;
484 	pgoff_t index;
485 	unsigned long length = 0;
486 	struct folio_batch fbatch;
487 	struct folio *folio;
488 
489 	if (inode->i_mapping->nrpages == 0)
490 		return 0;
491 
492 	index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
493 
494 	folio_batch_init(&fbatch);
495 
496 repeat:
497 	nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
498 			&fbatch);
499 	if (nr_folios == 0)
500 		return length;
501 
502 	i = 0;
503 	do {
504 		folio = fbatch.folios[i];
505 
506 		folio_lock(folio);
507 		if (folio_buffers(folio)) {
508 			struct buffer_head *bh, *head;
509 			sector_t b;
510 
511 			b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
512 			bh = head = folio_buffers(folio);
513 			do {
514 				if (b < start_blk)
515 					continue;
516 				if (buffer_delay(bh)) {
517 					if (length == 0)
518 						*blkoff = b;
519 					length++;
520 				} else if (length > 0) {
521 					goto out_locked;
522 				}
523 			} while (++b, bh = bh->b_this_page, bh != head);
524 		} else {
525 			if (length > 0)
526 				goto out_locked;
527 		}
528 		folio_unlock(folio);
529 
530 	} while (++i < nr_folios);
531 
532 	folio_batch_release(&fbatch);
533 	cond_resched();
534 	goto repeat;
535 
536 out_locked:
537 	folio_unlock(folio);
538 	folio_batch_release(&fbatch);
539 	return length;
540 }
541