page.c

  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
 28static 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
 46struct 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 */
 74void 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 */
100void 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 * Return: false if the folio has dirty buffers, true otherwise.
139 */
140bool 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
153void 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.f, 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 */
197static 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
243int 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);
252repeat:
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 (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 */
298void 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);
306repeat:
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 */
361void nilfs_clear_dirty_pages(struct address_space *mapping)
362{
363	struct folio_batch fbatch;
364	unsigned int i;
365	pgoff_t index = 0;
366
367	folio_batch_init(&fbatch);
368
369	while (filemap_get_folios_tag(mapping, &index, (pgoff_t)-1,
370				PAGECACHE_TAG_DIRTY, &fbatch)) {
371		for (i = 0; i < folio_batch_count(&fbatch); i++) {
372			struct folio *folio = fbatch.folios[i];
373
374			folio_lock(folio);
375
376			/*
377			 * This folio may have been removed from the address
378			 * space by truncation or invalidation when the lock
379			 * was acquired.  Skip processing in that case.
380			 */
381			if (likely(folio->mapping == mapping))
382				nilfs_clear_folio_dirty(folio);
383
384			folio_unlock(folio);
385		}
386		folio_batch_release(&fbatch);
387		cond_resched();
388	}
389}
390
391/**
392 * nilfs_clear_folio_dirty - discard dirty folio
393 * @folio: dirty folio that will be discarded
394 *
395 * nilfs_clear_folio_dirty() clears working states including dirty state for
396 * the folio and its buffers.  If the folio has buffers, clear only if it is
397 * confirmed that none of the buffer heads are busy (none have valid
398 * references and none are locked).
399 */
400void nilfs_clear_folio_dirty(struct folio *folio)
401{
402	struct buffer_head *bh, *head;
403
404	BUG_ON(!folio_test_locked(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		bool busy, invalidated = false;
414
415recheck_buffers:
416		busy = false;
417		bh = head;
418		do {
419			if (atomic_read(&bh->b_count) | buffer_locked(bh)) {
420				busy = true;
421				break;
422			}
423		} while (bh = bh->b_this_page, bh != head);
424
425		if (busy) {
426			if (invalidated)
427				return;
428			invalidate_bh_lrus();
429			invalidated = true;
430			goto recheck_buffers;
431		}
432
433		bh = head;
434		do {
435			lock_buffer(bh);
436			set_mask_bits(&bh->b_state, clear_bits, 0);
437			unlock_buffer(bh);
438		} while (bh = bh->b_this_page, bh != head);
439	}
440
441	folio_clear_uptodate(folio);
442	folio_clear_mappedtodisk(folio);
443	folio_clear_checked(folio);
444	__nilfs_clear_folio_dirty(folio);
445}
446
447unsigned int nilfs_page_count_clean_buffers(struct folio *folio,
448					    unsigned int from, unsigned int to)
449{
450	unsigned int block_start, block_end;
451	struct buffer_head *bh, *head;
452	unsigned int nc = 0;
453
454	for (bh = head = folio_buffers(folio), block_start = 0;
455	     bh != head || !block_start;
456	     block_start = block_end, bh = bh->b_this_page) {
457		block_end = block_start + bh->b_size;
458		if (block_end > from && block_start < to && !buffer_dirty(bh))
459			nc++;
460	}
461	return nc;
462}
463
464/*
465 * NILFS2 needs clear_page_dirty() in the following two cases:
466 *
467 * 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
468 *    flag of pages when it copies back pages from shadow cache to the
469 *    original cache.
470 *
471 * 2) Some B-tree operations like insertion or deletion may dispose buffers
472 *    in dirty state, and this needs to cancel the dirty state of their pages.
473 */
474void __nilfs_clear_folio_dirty(struct folio *folio)
475{
476	struct address_space *mapping = folio->mapping;
477
478	if (mapping) {
479		xa_lock_irq(&mapping->i_pages);
480		if (folio_test_dirty(folio)) {
481			__xa_clear_mark(&mapping->i_pages, folio->index,
482					     PAGECACHE_TAG_DIRTY);
483			xa_unlock_irq(&mapping->i_pages);
484			folio_clear_dirty_for_io(folio);
485			return;
486		}
487		xa_unlock_irq(&mapping->i_pages);
488		return;
489	}
490	folio_clear_dirty(folio);
491}
492
493/**
494 * nilfs_find_uncommitted_extent - find extent of uncommitted data
495 * @inode: inode
496 * @start_blk: start block offset (in)
497 * @blkoff: start offset of the found extent (out)
498 *
499 * This function searches an extent of buffers marked "delayed" which
500 * starts from a block offset equal to or larger than @start_blk.  If
501 * such an extent was found, this will store the start offset in
502 * @blkoff and return its length in blocks.
503 *
504 * Return: Length in blocks of found extent, 0 otherwise.
505 */
506unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
507					    sector_t start_blk,
508					    sector_t *blkoff)
509{
510	unsigned int i, nr_folios;
511	pgoff_t index;
512	unsigned long length = 0;
513	struct folio_batch fbatch;
514	struct folio *folio;
515
516	if (inode->i_mapping->nrpages == 0)
517		return 0;
518
519	index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
520
521	folio_batch_init(&fbatch);
522
523repeat:
524	nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
525			&fbatch);
526	if (nr_folios == 0)
527		return length;
528
529	i = 0;
530	do {
531		folio = fbatch.folios[i];
532
533		folio_lock(folio);
534		if (folio_buffers(folio)) {
535			struct buffer_head *bh, *head;
536			sector_t b;
537
538			b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
539			bh = head = folio_buffers(folio);
540			do {
541				if (b < start_blk)
542					continue;
543				if (buffer_delay(bh)) {
544					if (length == 0)
545						*blkoff = b;
546					length++;
547				} else if (length > 0) {
548					goto out_locked;
549				}
550			} while (++b, bh = bh->b_this_page, bh != head);
551		} else {
552			if (length > 0)
553				goto out_locked;
554		}
555		folio_unlock(folio);
556
557	} while (++i < nr_folios);
558
559	folio_batch_release(&fbatch);
560	cond_resched();
561	goto repeat;
562
563out_locked:
564	folio_unlock(folio);
565	folio_batch_release(&fbatch);
566	return length;
567}