summaryrefslogtreecommitdiff
path: root/fs/btrfs/subpage.c
blob: 0e49dab8dad2480243f4d32e6ee934c0f2b35b67 (plain)
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
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
// SPDX-License-Identifier: GPL-2.0

#include <linux/slab.h>
#include "messages.h"
#include "ctree.h"
#include "subpage.h"
#include "btrfs_inode.h"

/*
 * Subpage (sectorsize < PAGE_SIZE) support overview:
 *
 * Limitations:
 *
 * - Only support 64K page size for now
 *   This is to make metadata handling easier, as 64K page would ensure
 *   all nodesize would fit inside one page, thus we don't need to handle
 *   cases where a tree block crosses several pages.
 *
 * - Only metadata read-write for now
 *   The data read-write part is in development.
 *
 * - Metadata can't cross 64K page boundary
 *   btrfs-progs and kernel have done that for a while, thus only ancient
 *   filesystems could have such problem.  For such case, do a graceful
 *   rejection.
 *
 * Special behavior:
 *
 * - Metadata
 *   Metadata read is fully supported.
 *   Meaning when reading one tree block will only trigger the read for the
 *   needed range, other unrelated range in the same page will not be touched.
 *
 *   Metadata write support is partial.
 *   The writeback is still for the full page, but we will only submit
 *   the dirty extent buffers in the page.
 *
 *   This means, if we have a metadata page like this:
 *
 *   Page offset
 *   0         16K         32K         48K        64K
 *   |/////////|           |///////////|
 *        \- Tree block A        \- Tree block B
 *
 *   Even if we just want to writeback tree block A, we will also writeback
 *   tree block B if it's also dirty.
 *
 *   This may cause extra metadata writeback which results more COW.
 *
 * Implementation:
 *
 * - Common
 *   Both metadata and data will use a new structure, btrfs_subpage, to
 *   record the status of each sector inside a page.  This provides the extra
 *   granularity needed.
 *
 * - Metadata
 *   Since we have multiple tree blocks inside one page, we can't rely on page
 *   locking anymore, or we will have greatly reduced concurrency or even
 *   deadlocks (hold one tree lock while trying to lock another tree lock in
 *   the same page).
 *
 *   Thus for metadata locking, subpage support relies on io_tree locking only.
 *   This means a slightly higher tree locking latency.
 */

bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping)
{
	if (fs_info->sectorsize >= PAGE_SIZE)
		return false;

	/*
	 * Only data pages (either through DIO or compression) can have no
	 * mapping. And if page->mapping->host is data inode, it's subpage.
	 * As we have ruled our sectorsize >= PAGE_SIZE case already.
	 */
	if (!mapping || !mapping->host || is_data_inode(mapping->host))
		return true;

	/*
	 * Now the only remaining case is metadata, which we only go subpage
	 * routine if nodesize < PAGE_SIZE.
	 */
	if (fs_info->nodesize < PAGE_SIZE)
		return true;
	return false;
}

void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize)
{
	unsigned int cur = 0;
	unsigned int nr_bits;

	ASSERT(IS_ALIGNED(PAGE_SIZE, sectorsize));

	nr_bits = PAGE_SIZE / sectorsize;
	subpage_info->bitmap_nr_bits = nr_bits;

	subpage_info->uptodate_offset = cur;
	cur += nr_bits;

	subpage_info->dirty_offset = cur;
	cur += nr_bits;

	subpage_info->writeback_offset = cur;
	cur += nr_bits;

	subpage_info->ordered_offset = cur;
	cur += nr_bits;

	subpage_info->checked_offset = cur;
	cur += nr_bits;

	subpage_info->total_nr_bits = cur;
}

int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
			 struct folio *folio, enum btrfs_subpage_type type)
{
	struct btrfs_subpage *subpage;

	/*
	 * We have cases like a dummy extent buffer page, which is not mapped
	 * and doesn't need to be locked.
	 */
	if (folio->mapping)
		ASSERT(folio_test_locked(folio));

	/* Either not subpage, or the folio already has private attached. */
	if (!btrfs_is_subpage(fs_info, folio->mapping) || folio_test_private(folio))
		return 0;

	subpage = btrfs_alloc_subpage(fs_info, type);
	if (IS_ERR(subpage))
		return  PTR_ERR(subpage);

	folio_attach_private(folio, subpage);
	return 0;
}

void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, struct folio *folio)
{
	struct btrfs_subpage *subpage;

	/* Either not subpage, or the folio already has private attached. */
	if (!btrfs_is_subpage(fs_info, folio->mapping) || !folio_test_private(folio))
		return;

	subpage = folio_detach_private(folio);
	ASSERT(subpage);
	btrfs_free_subpage(subpage);
}

struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
					  enum btrfs_subpage_type type)
{
	struct btrfs_subpage *ret;
	unsigned int real_size;

	ASSERT(fs_info->sectorsize < PAGE_SIZE);

	real_size = struct_size(ret, bitmaps,
			BITS_TO_LONGS(fs_info->subpage_info->total_nr_bits));
	ret = kzalloc(real_size, GFP_NOFS);
	if (!ret)
		return ERR_PTR(-ENOMEM);

	spin_lock_init(&ret->lock);
	if (type == BTRFS_SUBPAGE_METADATA) {
		atomic_set(&ret->eb_refs, 0);
	} else {
		atomic_set(&ret->readers, 0);
		atomic_set(&ret->writers, 0);
	}
	return ret;
}

void btrfs_free_subpage(struct btrfs_subpage *subpage)
{
	kfree(subpage);
}

/*
 * Increase the eb_refs of current subpage.
 *
 * This is important for eb allocation, to prevent race with last eb freeing
 * of the same page.
 * With the eb_refs increased before the eb inserted into radix tree,
 * detach_extent_buffer_page() won't detach the folio private while we're still
 * allocating the extent buffer.
 */
void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio)
{
	struct btrfs_subpage *subpage;

	if (!btrfs_is_subpage(fs_info, folio->mapping))
		return;

	ASSERT(folio_test_private(folio) && folio->mapping);
	lockdep_assert_held(&folio->mapping->i_private_lock);

	subpage = folio_get_private(folio);
	atomic_inc(&subpage->eb_refs);
}

void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio)
{
	struct btrfs_subpage *subpage;

	if (!btrfs_is_subpage(fs_info, folio->mapping))
		return;

	ASSERT(folio_test_private(folio) && folio->mapping);
	lockdep_assert_held(&folio->mapping->i_private_lock);

	subpage = folio_get_private(folio);
	ASSERT(atomic_read(&subpage->eb_refs));
	atomic_dec(&subpage->eb_refs);
}

static void btrfs_subpage_assert(const struct btrfs_fs_info *fs_info,
				 struct folio *folio, u64 start, u32 len)
{
	/* For subpage support, the folio must be single page. */
	ASSERT(folio_order(folio) == 0);

	/* Basic checks */
	ASSERT(folio_test_private(folio) && folio_get_private(folio));
	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
	       IS_ALIGNED(len, fs_info->sectorsize));
	/*
	 * The range check only works for mapped page, we can still have
	 * unmapped page like dummy extent buffer pages.
	 */
	if (folio->mapping)
		ASSERT(folio_pos(folio) <= start &&
		       start + len <= folio_pos(folio) + PAGE_SIZE);
}

void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
				struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	const int nbits = len >> fs_info->sectorsize_bits;

	btrfs_subpage_assert(fs_info, folio, start, len);

	atomic_add(nbits, &subpage->readers);
}

void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
			      struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	const int nbits = len >> fs_info->sectorsize_bits;
	bool is_data;
	bool last;

	btrfs_subpage_assert(fs_info, folio, start, len);
	is_data = is_data_inode(folio->mapping->host);
	ASSERT(atomic_read(&subpage->readers) >= nbits);
	last = atomic_sub_and_test(nbits, &subpage->readers);

	/*
	 * For data we need to unlock the page if the last read has finished.
	 *
	 * And please don't replace @last with atomic_sub_and_test() call
	 * inside if () condition.
	 * As we want the atomic_sub_and_test() to be always executed.
	 */
	if (is_data && last)
		folio_unlock(folio);
}

static void btrfs_subpage_clamp_range(struct folio *folio, u64 *start, u32 *len)
{
	u64 orig_start = *start;
	u32 orig_len = *len;

	*start = max_t(u64, folio_pos(folio), orig_start);
	/*
	 * For certain call sites like btrfs_drop_pages(), we may have pages
	 * beyond the target range. In that case, just set @len to 0, subpage
	 * helpers can handle @len == 0 without any problem.
	 */
	if (folio_pos(folio) >= orig_start + orig_len)
		*len = 0;
	else
		*len = min_t(u64, folio_pos(folio) + PAGE_SIZE,
			     orig_start + orig_len) - *start;
}

void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info,
				struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	const int nbits = (len >> fs_info->sectorsize_bits);
	int ret;

	btrfs_subpage_assert(fs_info, folio, start, len);

	ASSERT(atomic_read(&subpage->readers) == 0);
	ret = atomic_add_return(nbits, &subpage->writers);
	ASSERT(ret == nbits);
}

bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
				       struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	const int nbits = (len >> fs_info->sectorsize_bits);

	btrfs_subpage_assert(fs_info, folio, start, len);

	/*
	 * We have call sites passing @lock_page into
	 * extent_clear_unlock_delalloc() for compression path.
	 *
	 * This @locked_page is locked by plain lock_page(), thus its
	 * subpage::writers is 0.  Handle them in a special way.
	 */
	if (atomic_read(&subpage->writers) == 0)
		return true;

	ASSERT(atomic_read(&subpage->writers) >= nbits);
	return atomic_sub_and_test(nbits, &subpage->writers);
}

/*
 * Lock a folio for delalloc page writeback.
 *
 * Return -EAGAIN if the page is not properly initialized.
 * Return 0 with the page locked, and writer counter updated.
 *
 * Even with 0 returned, the page still need extra check to make sure
 * it's really the correct page, as the caller is using
 * filemap_get_folios_contig(), which can race with page invalidating.
 */
int btrfs_folio_start_writer_lock(const struct btrfs_fs_info *fs_info,
				  struct folio *folio, u64 start, u32 len)
{
	if (unlikely(!fs_info) || !btrfs_is_subpage(fs_info, folio->mapping)) {
		folio_lock(folio);
		return 0;
	}
	folio_lock(folio);
	if (!folio_test_private(folio) || !folio_get_private(folio)) {
		folio_unlock(folio);
		return -EAGAIN;
	}
	btrfs_subpage_clamp_range(folio, &start, &len);
	btrfs_subpage_start_writer(fs_info, folio, start, len);
	return 0;
}

void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,
				 struct folio *folio, u64 start, u32 len)
{
	if (unlikely(!fs_info) || !btrfs_is_subpage(fs_info, folio->mapping)) {
		folio_unlock(folio);
		return;
	}
	btrfs_subpage_clamp_range(folio, &start, &len);
	if (btrfs_subpage_end_and_test_writer(fs_info, folio, start, len))
		folio_unlock(folio);
}

#define subpage_calc_start_bit(fs_info, folio, name, start, len)	\
({									\
	unsigned int start_bit;						\
									\
	btrfs_subpage_assert(fs_info, folio, start, len);		\
	start_bit = offset_in_page(start) >> fs_info->sectorsize_bits;	\
	start_bit += fs_info->subpage_info->name##_offset;		\
	start_bit;							\
})

#define subpage_test_bitmap_all_set(fs_info, subpage, name)		\
	bitmap_test_range_all_set(subpage->bitmaps,			\
			fs_info->subpage_info->name##_offset,		\
			fs_info->subpage_info->bitmap_nr_bits)

#define subpage_test_bitmap_all_zero(fs_info, subpage, name)		\
	bitmap_test_range_all_zero(subpage->bitmaps,			\
			fs_info->subpage_info->name##_offset,		\
			fs_info->subpage_info->bitmap_nr_bits)

void btrfs_subpage_set_uptodate(const struct btrfs_fs_info *fs_info,
				struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							uptodate, start, len);
	unsigned long flags;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	if (subpage_test_bitmap_all_set(fs_info, subpage, uptodate))
		folio_mark_uptodate(folio);
	spin_unlock_irqrestore(&subpage->lock, flags);
}

void btrfs_subpage_clear_uptodate(const struct btrfs_fs_info *fs_info,
				  struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							uptodate, start, len);
	unsigned long flags;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	folio_clear_uptodate(folio);
	spin_unlock_irqrestore(&subpage->lock, flags);
}

void btrfs_subpage_set_dirty(const struct btrfs_fs_info *fs_info,
			     struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							dirty, start, len);
	unsigned long flags;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	spin_unlock_irqrestore(&subpage->lock, flags);
	folio_mark_dirty(folio);
}

/*
 * Extra clear_and_test function for subpage dirty bitmap.
 *
 * Return true if we're the last bits in the dirty_bitmap and clear the
 * dirty_bitmap.
 * Return false otherwise.
 *
 * NOTE: Callers should manually clear page dirty for true case, as we have
 * extra handling for tree blocks.
 */
bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
					struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							dirty, start, len);
	unsigned long flags;
	bool last = false;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	if (subpage_test_bitmap_all_zero(fs_info, subpage, dirty))
		last = true;
	spin_unlock_irqrestore(&subpage->lock, flags);
	return last;
}

void btrfs_subpage_clear_dirty(const struct btrfs_fs_info *fs_info,
			       struct folio *folio, u64 start, u32 len)
{
	bool last;

	last = btrfs_subpage_clear_and_test_dirty(fs_info, folio, start, len);
	if (last)
		folio_clear_dirty_for_io(folio);
}

void btrfs_subpage_set_writeback(const struct btrfs_fs_info *fs_info,
				 struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							writeback, start, len);
	unsigned long flags;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	if (!folio_test_writeback(folio))
		folio_start_writeback(folio);
	spin_unlock_irqrestore(&subpage->lock, flags);
}

void btrfs_subpage_clear_writeback(const struct btrfs_fs_info *fs_info,
				   struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							writeback, start, len);
	unsigned long flags;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	if (subpage_test_bitmap_all_zero(fs_info, subpage, writeback)) {
		ASSERT(folio_test_writeback(folio));
		folio_end_writeback(folio);
	}
	spin_unlock_irqrestore(&subpage->lock, flags);
}

void btrfs_subpage_set_ordered(const struct btrfs_fs_info *fs_info,
			       struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							ordered, start, len);
	unsigned long flags;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	folio_set_ordered(folio);
	spin_unlock_irqrestore(&subpage->lock, flags);
}

void btrfs_subpage_clear_ordered(const struct btrfs_fs_info *fs_info,
				 struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							ordered, start, len);
	unsigned long flags;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	if (subpage_test_bitmap_all_zero(fs_info, subpage, ordered))
		folio_clear_ordered(folio);
	spin_unlock_irqrestore(&subpage->lock, flags);
}

void btrfs_subpage_set_checked(const struct btrfs_fs_info *fs_info,
			       struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							checked, start, len);
	unsigned long flags;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	if (subpage_test_bitmap_all_set(fs_info, subpage, checked))
		folio_set_checked(folio);
	spin_unlock_irqrestore(&subpage->lock, flags);
}

void btrfs_subpage_clear_checked(const struct btrfs_fs_info *fs_info,
				 struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
							checked, start, len);
	unsigned long flags;

	spin_lock_irqsave(&subpage->lock, flags);
	bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
	folio_clear_checked(folio);
	spin_unlock_irqrestore(&subpage->lock, flags);
}

/*
 * Unlike set/clear which is dependent on each page status, for test all bits
 * are tested in the same way.
 */
#define IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(name)				\
bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info,	\
			       struct folio *folio, u64 start, u32 len)	\
{									\
	struct btrfs_subpage *subpage = folio_get_private(folio);	\
	unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,	\
						name, start, len);	\
	unsigned long flags;						\
	bool ret;							\
									\
	spin_lock_irqsave(&subpage->lock, flags);			\
	ret = bitmap_test_range_all_set(subpage->bitmaps, start_bit,	\
				len >> fs_info->sectorsize_bits);	\
	spin_unlock_irqrestore(&subpage->lock, flags);			\
	return ret;							\
}
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(uptodate);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(dirty);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(writeback);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(ordered);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(checked);

/*
 * Note that, in selftests (extent-io-tests), we can have empty fs_info passed
 * in.  We only test sectorsize == PAGE_SIZE cases so far, thus we can fall
 * back to regular sectorsize branch.
 */
#define IMPLEMENT_BTRFS_PAGE_OPS(name, folio_set_func,			\
				 folio_clear_func, folio_test_func)	\
void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info,	\
			    struct folio *folio, u64 start, u32 len)	\
{									\
	if (unlikely(!fs_info) ||					\
	    !btrfs_is_subpage(fs_info, folio->mapping)) {		\
		folio_set_func(folio);					\
		return;							\
	}								\
	btrfs_subpage_set_##name(fs_info, folio, start, len);		\
}									\
void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info,	\
			      struct folio *folio, u64 start, u32 len)	\
{									\
	if (unlikely(!fs_info) ||					\
	    !btrfs_is_subpage(fs_info, folio->mapping)) {		\
		folio_clear_func(folio);				\
		return;							\
	}								\
	btrfs_subpage_clear_##name(fs_info, folio, start, len);		\
}									\
bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info,	\
			     struct folio *folio, u64 start, u32 len)	\
{									\
	if (unlikely(!fs_info) ||					\
	    !btrfs_is_subpage(fs_info, folio->mapping))			\
		return folio_test_func(folio);				\
	return btrfs_subpage_test_##name(fs_info, folio, start, len);	\
}									\
void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info,	\
				  struct folio *folio, u64 start, u32 len) \
{									\
	if (unlikely(!fs_info) ||					\
	    !btrfs_is_subpage(fs_info, folio->mapping)) {		\
		folio_set_func(folio);					\
		return;							\
	}								\
	btrfs_subpage_clamp_range(folio, &start, &len);			\
	btrfs_subpage_set_##name(fs_info, folio, start, len);		\
}									\
void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \
				    struct folio *folio, u64 start, u32 len) \
{									\
	if (unlikely(!fs_info) ||					\
	    !btrfs_is_subpage(fs_info, folio->mapping)) {		\
		folio_clear_func(folio);				\
		return;							\
	}								\
	btrfs_subpage_clamp_range(folio, &start, &len);			\
	btrfs_subpage_clear_##name(fs_info, folio, start, len);		\
}									\
bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info,	\
				   struct folio *folio, u64 start, u32 len) \
{									\
	if (unlikely(!fs_info) ||					\
	    !btrfs_is_subpage(fs_info, folio->mapping))			\
		return folio_test_func(folio);				\
	btrfs_subpage_clamp_range(folio, &start, &len);			\
	return btrfs_subpage_test_##name(fs_info, folio, start, len);	\
}
IMPLEMENT_BTRFS_PAGE_OPS(uptodate, folio_mark_uptodate, folio_clear_uptodate,
			 folio_test_uptodate);
IMPLEMENT_BTRFS_PAGE_OPS(dirty, folio_mark_dirty, folio_clear_dirty_for_io,
			 folio_test_dirty);
IMPLEMENT_BTRFS_PAGE_OPS(writeback, folio_start_writeback, folio_end_writeback,
			 folio_test_writeback);
IMPLEMENT_BTRFS_PAGE_OPS(ordered, folio_set_ordered, folio_clear_ordered,
			 folio_test_ordered);
IMPLEMENT_BTRFS_PAGE_OPS(checked, folio_set_checked, folio_clear_checked,
			 folio_test_checked);

/*
 * Make sure not only the page dirty bit is cleared, but also subpage dirty bit
 * is cleared.
 */
void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, struct folio *folio)
{
	struct btrfs_subpage *subpage = folio_get_private(folio);

	if (!IS_ENABLED(CONFIG_BTRFS_ASSERT))
		return;

	ASSERT(!folio_test_dirty(folio));
	if (!btrfs_is_subpage(fs_info, folio->mapping))
		return;

	ASSERT(folio_test_private(folio) && folio_get_private(folio));
	ASSERT(subpage_test_bitmap_all_zero(fs_info, subpage, dirty));
}

/*
 * Handle different locked pages with different page sizes:
 *
 * - Page locked by plain lock_page()
 *   It should not have any subpage::writers count.
 *   Can be unlocked by unlock_page().
 *   This is the most common locked page for __extent_writepage() called
 *   inside extent_write_cache_pages().
 *   Rarer cases include the @locked_page from extent_write_locked_range().
 *
 * - Page locked by lock_delalloc_pages()
 *   There is only one caller, all pages except @locked_page for
 *   extent_write_locked_range().
 *   In this case, we have to call subpage helper to handle the case.
 */
void btrfs_folio_unlock_writer(struct btrfs_fs_info *fs_info,
			       struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage *subpage;

	ASSERT(folio_test_locked(folio));
	/* For non-subpage case, we just unlock the page */
	if (!btrfs_is_subpage(fs_info, folio->mapping)) {
		folio_unlock(folio);
		return;
	}

	ASSERT(folio_test_private(folio) && folio_get_private(folio));
	subpage = folio_get_private(folio);

	/*
	 * For subpage case, there are two types of locked page.  With or
	 * without writers number.
	 *
	 * Since we own the page lock, no one else could touch subpage::writers
	 * and we are safe to do several atomic operations without spinlock.
	 */
	if (atomic_read(&subpage->writers) == 0) {
		/* No writers, locked by plain lock_page() */
		folio_unlock(folio);
		return;
	}

	/* Have writers, use proper subpage helper to end it */
	btrfs_folio_end_writer_lock(fs_info, folio, start, len);
}

#define GET_SUBPAGE_BITMAP(subpage, subpage_info, name, dst)		\
	bitmap_cut(dst, subpage->bitmaps, 0,				\
		   subpage_info->name##_offset, subpage_info->bitmap_nr_bits)

void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info,
				      struct folio *folio, u64 start, u32 len)
{
	struct btrfs_subpage_info *subpage_info = fs_info->subpage_info;
	struct btrfs_subpage *subpage;
	unsigned long uptodate_bitmap;
	unsigned long error_bitmap;
	unsigned long dirty_bitmap;
	unsigned long writeback_bitmap;
	unsigned long ordered_bitmap;
	unsigned long checked_bitmap;
	unsigned long flags;

	ASSERT(folio_test_private(folio) && folio_get_private(folio));
	ASSERT(subpage_info);
	subpage = folio_get_private(folio);

	spin_lock_irqsave(&subpage->lock, flags);
	GET_SUBPAGE_BITMAP(subpage, subpage_info, uptodate, &uptodate_bitmap);
	GET_SUBPAGE_BITMAP(subpage, subpage_info, dirty, &dirty_bitmap);
	GET_SUBPAGE_BITMAP(subpage, subpage_info, writeback, &writeback_bitmap);
	GET_SUBPAGE_BITMAP(subpage, subpage_info, ordered, &ordered_bitmap);
	GET_SUBPAGE_BITMAP(subpage, subpage_info, checked, &checked_bitmap);
	spin_unlock_irqrestore(&subpage->lock, flags);

	dump_page(folio_page(folio, 0), "btrfs subpage dump");
	btrfs_warn(fs_info,
"start=%llu len=%u page=%llu, bitmaps uptodate=%*pbl error=%*pbl dirty=%*pbl writeback=%*pbl ordered=%*pbl checked=%*pbl",
		    start, len, folio_pos(folio),
		    subpage_info->bitmap_nr_bits, &uptodate_bitmap,
		    subpage_info->bitmap_nr_bits, &error_bitmap,
		    subpage_info->bitmap_nr_bits, &dirty_bitmap,
		    subpage_info->bitmap_nr_bits, &writeback_bitmap,
		    subpage_info->bitmap_nr_bits, &ordered_bitmap,
		    subpage_info->bitmap_nr_bits, &checked_bitmap);
}