aboutsummaryrefslogtreecommitdiffstats
path: root/fs/nilfs2/page.c
blob: 3da37cc5de3479985999639cbc08cbfd4dfa2884 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
/*
 * page.c - buffer/page management specific to NILFS
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Written by Ryusuke Konishi <ryusuke@osrg.net>,
 *            Seiji Kihara <kihara@osrg.net>.
 */

#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/swap.h>
#include <linux/bitops.h>
#include <linux/page-flags.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/pagevec.h>
#include <linux/gfp.h>
#include "nilfs.h"
#include "page.h"
#include "mdt.h"


#define NILFS_BUFFER_INHERENT_BITS  \
	((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \
	 (1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Allocated) | \
	 (1UL << BH_NILFS_Checked))

static struct buffer_head *
__nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
		       int blkbits, unsigned long b_state)

{
	unsigned long first_block;
	struct buffer_head *bh;

	if (!page_has_buffers(page))
		create_empty_buffers(page, 1 << blkbits, b_state);

	first_block = (unsigned long)index << (PAGE_CACHE_SHIFT - blkbits);
	bh = nilfs_page_get_nth_block(page, block - first_block);

	touch_buffer(bh);
	wait_on_buffer(bh);
	return bh;
}

/*
 * Since the page cache of B-tree node pages or data page cache of pseudo
 * inodes does not have a valid mapping->host pointer, calling
 * mark_buffer_dirty() for their buffers causes a NULL pointer dereference;
 * it calls __mark_inode_dirty(NULL) through __set_page_dirty().
 * To avoid this problem, the old style mark_buffer_dirty() is used instead.
 */
void nilfs_mark_buffer_dirty(struct buffer_head *bh)
{
	if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
		__set_page_dirty_nobuffers(bh->b_page);
}

struct buffer_head *nilfs_grab_buffer(struct inode *inode,
				      struct address_space *mapping,
				      unsigned long blkoff,
				      unsigned long b_state)
{
	int blkbits = inode->i_blkbits;
	pgoff_t index = blkoff >> (PAGE_CACHE_SHIFT - blkbits);
	struct page *page;
	struct buffer_head *bh;

	page = grab_cache_page(mapping, index);
	if (unlikely(!page))
		return NULL;

	bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
	if (unlikely(!bh)) {
		unlock_page(page);
		page_cache_release(page);
		return NULL;
	}
	return bh;
}

/**
 * nilfs_forget_buffer - discard dirty state
 * @inode: owner inode of the buffer
 * @bh: buffer head of the buffer to be discarded
 */
void nilfs_forget_buffer(struct buffer_head *bh)
{
	struct page *page = bh->b_page;

	lock_buffer(bh);
	clear_buffer_nilfs_volatile(bh);
	clear_buffer_nilfs_checked(bh);
	clear_buffer_nilfs_redirected(bh);
	clear_buffer_dirty(bh);
	if (nilfs_page_buffers_clean(page))
		__nilfs_clear_page_dirty(page);

	clear_buffer_uptodate(bh);
	clear_buffer_mapped(bh);
	bh->b_blocknr = -1;
	ClearPageUptodate(page);
	ClearPageMappedToDisk(page);
	unlock_buffer(bh);
	brelse(bh);
}

/**
 * nilfs_copy_buffer -- copy buffer data and flags
 * @dbh: destination buffer
 * @sbh: source buffer
 */
void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
{
	void *kaddr0, *kaddr1;
	unsigned long bits;
	struct page *spage = sbh->b_page, *dpage = dbh->b_page;
	struct buffer_head *bh;

	kaddr0 = kmap_atomic(spage, KM_USER0);
	kaddr1 = kmap_atomic(dpage, KM_USER1);
	memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
	kunmap_atomic(kaddr1, KM_USER1);
	kunmap_atomic(kaddr0, KM_USER0);

	dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
	dbh->b_blocknr = sbh->b_blocknr;
	dbh->b_bdev = sbh->b_bdev;

	bh = dbh;
	bits = sbh->b_state & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
	while ((bh = bh->b_this_page) != dbh) {
		lock_buffer(bh);
		bits &= bh->b_state;
		unlock_buffer(bh);
	}
	if (bits & (1UL << BH_Uptodate))
		SetPageUptodate(dpage);
	else
		ClearPageUptodate(dpage);
	if (bits & (1UL << BH_Mapped))
		SetPageMappedToDisk(dpage);
	else
		ClearPageMappedToDisk(dpage);
}

/**
 * nilfs_page_buffers_clean - check if a page has dirty buffers or not.
 * @page: page to be checked
 *
 * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
 * Otherwise, it returns non-zero value.
 */
int nilfs_page_buffers_clean(struct page *page)
{
	struct buffer_head *bh, *head;

	bh = head = page_buffers(page);
	do {
		if (buffer_dirty(bh))
			return 0;
		bh = bh->b_this_page;
	} while (bh != head);
	return 1;
}

void nilfs_page_bug(struct page *page)
{
	struct address_space *m;
	unsigned long ino = 0;

	if (unlikely(!page)) {
		printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
		return;
	}

	m = page->mapping;
	if (m) {
		struct inode *inode = NILFS_AS_I(m);
		if (inode != NULL)
			ino = inode->i_ino;
	}
	printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
	       "mapping=%p ino=%lu\n",
	       page, atomic_read(&page->_count),
	       (unsigned long long)page->index, page->flags, m, ino);

	if (page_has_buffers(page)) {
		struct buffer_head *bh, *head;
		int i = 0;

		bh = head = page_buffers(page);
		do {
			printk(KERN_CRIT
			       " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
			       i++, bh, atomic_read(&bh->b_count),
			       (unsigned long long)bh->b_blocknr, bh->b_state);
			bh = bh->b_this_page;
		} while (bh != head);
	}
}

/**
 * nilfs_alloc_private_page - allocate a private page with buffer heads
 *
 * Return Value: On success, a pointer to the allocated page is returned.
 * On error, NULL is returned.
 */
struct page *nilfs_alloc_private_page(struct block_device *bdev, int size,
				      unsigned long state)
{
	struct buffer_head *bh, *head, *tail;
	struct page *page;

	page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */
	if (unlikely(!page))
		return NULL;

	lock_page(page);
	head = alloc_page_buffers(page, size, 0);
	if (unlikely(!head)) {
		unlock_page(page);
		__free_page(page);
		return NULL;
	}

	bh = head;
	do {
		bh->b_state = (1UL << BH_NILFS_Allocated) | state;
		tail = bh;
		bh->b_bdev = bdev;
		bh = bh->b_this_page;
	} while (bh);

	tail->b_this_page = head;
	attach_page_buffers(page, head);

	return page;
}

void nilfs_free_private_page(struct page *page)
{
	BUG_ON(!PageLocked(page));
	BUG_ON(page->mapping);

	if (page_has_buffers(page) && !try_to_free_buffers(page))
		NILFS_PAGE_BUG(page, "failed to free page");

	unlock_page(page);
	__free_page(page);
}

/**
 * nilfs_copy_page -- copy the page with buffers
 * @dst: destination page
 * @src: source page
 * @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
 *
 * This function is for both data pages and btnode pages.  The dirty flag
 * should be treated by caller.  The page must not be under i/o.
 * Both src and dst page must be locked
 */
static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
{
	struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
	unsigned long mask = NILFS_BUFFER_INHERENT_BITS;

	BUG_ON(PageWriteback(dst));

	sbh = sbufs = page_buffers(src);
	if (!page_has_buffers(dst))
		create_empty_buffers(dst, sbh->b_size, 0);

	if (copy_dirty)
		mask |= (1UL << BH_Dirty);

	dbh = dbufs = page_buffers(dst);
	do {
		lock_buffer(sbh);
		lock_buffer(dbh);
		dbh->b_state = sbh->b_state & mask;
		dbh->b_blocknr = sbh->b_blocknr;
		dbh->b_bdev = sbh->b_bdev;
		sbh = sbh->b_this_page;
		dbh = dbh->b_this_page;
	} while (dbh != dbufs);

	copy_highpage(dst, src);

	if (PageUptodate(src) && !PageUptodate(dst))
		SetPageUptodate(dst);
	else if (!PageUptodate(src) && PageUptodate(dst))
		ClearPageUptodate(dst);
	if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
		SetPageMappedToDisk(dst);
	else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
		ClearPageMappedToDisk(dst);

	do {
		unlock_buffer(sbh);
		unlock_buffer(dbh);
		sbh = sbh->b_this_page;
		dbh = dbh->b_this_page;
	} while (dbh != dbufs);
}

int nilfs_copy_dirty_pages(struct address_space *dmap,
			   struct address_space *smap)
{
	struct pagevec pvec;
	unsigned int i;
	pgoff_t index = 0;
	int err = 0;

	pagevec_init(&pvec, 0);
repeat:
	if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
				PAGEVEC_SIZE))
		return 0;

	for (i = 0; i < pagevec_count(&pvec); i++) {
		struct page *page = pvec.pages[i], *dpage;

		lock_page(page);
		if (unlikely(!PageDirty(page)))
			NILFS_PAGE_BUG(page, "inconsistent dirty state");

		dpage = grab_cache_page(dmap, page->index);
		if (unlikely(!dpage)) {
			/* No empty page is added to the page cache */
			err = -ENOMEM;
			unlock_page(page);
			break;
		}
		if (unlikely(!page_has_buffers(page)))
			NILFS_PAGE_BUG(page,
				       "found empty page in dat page cache");

		nilfs_copy_page(dpage, page, 1);
		__set_page_dirty_nobuffers(dpage);

		unlock_page(dpage);
		page_cache_release(dpage);
		unlock_page(page);
	}
	pagevec_release(&pvec);
	cond_resched();

	if (likely(!err))
		goto repeat;
	return err;
}

/**
 * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
 * @dmap: destination page cache
 * @smap: source page cache
 *
 * No pages must no be added to the cache during this process.
 * This must be ensured by the caller.
 */
void nilfs_copy_back_pages(struct address_space *dmap,
			   struct address_space *smap)
{
	struct pagevec pvec;
	unsigned int i, n;
	pgoff_t index = 0;
	int err;

	pagevec_init(&pvec, 0);
repeat:
	n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
	if (!n)
		return;
	index = pvec.pages[n - 1]->index + 1;

	for (i = 0; i < pagevec_count(&pvec); i++) {
		struct page *page = pvec.pages[i], *dpage;
		pgoff_t offset = page->index;

		lock_page(page);
		dpage = find_lock_page(dmap, offset);
		if (dpage) {
			/* override existing page on the destination cache */
			WARN_ON(PageDirty(dpage));
			nilfs_copy_page(dpage, page, 0);
			unlock_page(dpage);
			page_cache_release(dpage);
		} else {
			struct page *page2;

			/* move the page to the destination cache */
			spin_lock_irq(&smap->tree_lock);
			page2 = radix_tree_delete(&smap->page_tree, offset);
			WARN_ON(page2 != page);

			smap->nrpages--;
			spin_unlock_irq(&smap->tree_lock);

			spin_lock_irq(&dmap->tree_lock);
			err = radix_tree_insert(&dmap->page_tree, offset, page);
			if (unlikely(err < 0)) {
				WARN_ON(err == -EEXIST);
				page->mapping = NULL;
				page_cache_release(page); /* for cache */
			} else {
				page->mapping = dmap;
				dmap->nrpages++;
				if (PageDirty(page))
					radix_tree_tag_set(&dmap->page_tree,
							   offset,
							   PAGECACHE_TAG_DIRTY);
			}
			spin_unlock_irq(&dmap->tree_lock);
		}
		unlock_page(page);
	}
	pagevec_release(&pvec);
	cond_resched();

	goto repeat;
}

void nilfs_clear_dirty_pages(struct address_space *mapping)
{
	struct pagevec pvec;
	unsigned int i;
	pgoff_t index = 0;

	pagevec_init(&pvec, 0);

	while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
				  PAGEVEC_SIZE)) {
		for (i = 0; i < pagevec_count(&pvec); i++) {
			struct page *page = pvec.pages[i];
			struct buffer_head *bh, *head;

			lock_page(page);
			ClearPageUptodate(page);
			ClearPageMappedToDisk(page);
			bh = head = page_buffers(page);
			do {
				lock_buffer(bh);
				clear_buffer_dirty(bh);
				clear_buffer_nilfs_volatile(bh);
				clear_buffer_nilfs_checked(bh);
				clear_buffer_nilfs_redirected(bh);
				clear_buffer_uptodate(bh);
				clear_buffer_mapped(bh);
				unlock_buffer(bh);
				bh = bh->b_this_page;
			} while (bh != head);

			__nilfs_clear_page_dirty(page);
			unlock_page(page);
		}
		pagevec_release(&pvec);
		cond_resched();
	}
}

unsigned nilfs_page_count_clean_buffers(struct page *page,
					unsigned from, unsigned to)
{
	unsigned block_start, block_end;
	struct buffer_head *bh, *head;
	unsigned nc = 0;

	for (bh = head = page_buffers(page), block_start = 0;
	     bh != head || !block_start;
	     block_start = block_end, bh = bh->b_this_page) {
		block_end = block_start + bh->b_size;
		if (block_end > from && block_start < to && !buffer_dirty(bh))
			nc++;
	}
	return nc;
}

void nilfs_mapping_init_once(struct address_space *mapping)
{
	memset(mapping, 0, sizeof(*mapping));
	INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
	spin_lock_init(&mapping->tree_lock);
	INIT_LIST_HEAD(&mapping->private_list);
	spin_lock_init(&mapping->private_lock);

	spin_lock_init(&mapping->i_mmap_lock);
	INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
	INIT_LIST_HEAD(&mapping->i_mmap_nonlinear);
}

void nilfs_mapping_init(struct address_space *mapping,
			struct backing_dev_info *bdi)
{
	mapping->host = NULL;
	mapping->flags = 0;
	mapping_set_gfp_mask(mapping, GFP_NOFS);
	mapping->assoc_mapping = NULL;
	mapping->backing_dev_info = bdi;
	mapping->a_ops = NULL;
}

/*
 * NILFS2 needs clear_page_dirty() in the following two cases:
 *
 * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
 *    page dirty flags when it copies back pages from the shadow cache
 *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
 *    (dat->{i_mapping,i_btnode_cache}).
 *
 * 2) Some B-tree operations like insertion or deletion may dispose buffers
 *    in dirty state, and this needs to cancel the dirty state of their pages.
 */
int __nilfs_clear_page_dirty(struct page *page)
{
	struct address_space *mapping = page->mapping;

	if (mapping) {
		spin_lock_irq(&mapping->tree_lock);
		if (test_bit(PG_dirty, &page->flags)) {
			radix_tree_tag_clear(&mapping->page_tree,
					     page_index(page),
					     PAGECACHE_TAG_DIRTY);
			spin_unlock_irq(&mapping->tree_lock);
			return clear_page_dirty_for_io(page);
		}
		spin_unlock_irq(&mapping->tree_lock);
		return 0;
	}
	return TestClearPageDirty(page);
}

/**
 * nilfs_find_uncommitted_extent - find extent of uncommitted data
 * @inode: inode
 * @start_blk: start block offset (in)
 * @blkoff: start offset of the found extent (out)
 *
 * This function searches an extent of buffers marked "delayed" which
 * starts from a block offset equal to or larger than @start_blk.  If
 * such an extent was found, this will store the start offset in
 * @blkoff and return its length in blocks.  Otherwise, zero is
 * returned.
 */
unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
					    sector_t start_blk,
					    sector_t *blkoff)
{
	unsigned int i;
	pgoff_t index;
	unsigned int nblocks_in_page;
	unsigned long length = 0;
	sector_t b;
	struct pagevec pvec;
	struct page *page;

	if (inode->i_mapping->nrpages == 0)
		return 0;

	index = start_blk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
	nblocks_in_page = 1U << (PAGE_CACHE_SHIFT - inode->i_blkbits);

	pagevec_init(&pvec, 0);

repeat:
	pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
					pvec.pages);
	if (pvec.nr == 0)
		return length;

	if (length > 0 && pvec.pages[0]->index > index)
		goto out;

	b = pvec.pages[0]->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
	i = 0;
	do {
		page = pvec.pages[i];

		lock_page(page);
		if (page_has_buffers(page)) {
			struct buffer_head *bh, *head;

			bh = head = page_buffers(page);
			do {
				if (b < start_blk)
					continue;
				if (buffer_delay(bh)) {
					if (length == 0)
						*blkoff = b;
					length++;
				} else if (length > 0) {
					goto out_locked;
				}
			} while (++b, bh = bh->b_this_page, bh != head);
		} else {
			if (length > 0)
				goto out_locked;

			b += nblocks_in_page;
		}
		unlock_page(page);

	} while (++i < pagevec_count(&pvec));

	index = page->index + 1;
	pagevec_release(&pvec);
	cond_resched();
	goto repeat;

out_locked:
	unlock_page(page);
out:
	pagevec_release(&pvec);
	return length;
}