summaryrefslogtreecommitdiff
path: root/fs/xfs/scrub/bmap.c
blob: 7badd6dfe5449631d170c999f0a2ed51f7814ef9 (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
// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2017 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_btree.h"
#include "xfs_bit.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_inode.h"
#include "xfs_alloc.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_rmap.h"
#include "xfs_rmap_btree.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/btree.h"

/* Set us up with an inode's bmap. */
int
xchk_setup_inode_bmap(
	struct xfs_scrub	*sc,
	struct xfs_inode	*ip)
{
	int			error;

	error = xchk_get_inode(sc, ip);
	if (error)
		goto out;

	sc->ilock_flags = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
	xfs_ilock(sc->ip, sc->ilock_flags);

	/*
	 * We don't want any ephemeral data fork updates sitting around
	 * while we inspect block mappings, so wait for directio to finish
	 * and flush dirty data if we have delalloc reservations.
	 */
	if (S_ISREG(VFS_I(sc->ip)->i_mode) &&
	    sc->sm->sm_type == XFS_SCRUB_TYPE_BMBTD) {
		inode_dio_wait(VFS_I(sc->ip));
		error = filemap_write_and_wait(VFS_I(sc->ip)->i_mapping);
		if (error)
			goto out;
	}

	/* Got the inode, lock it and we're ready to go. */
	error = xchk_trans_alloc(sc, 0);
	if (error)
		goto out;
	sc->ilock_flags |= XFS_ILOCK_EXCL;
	xfs_ilock(sc->ip, XFS_ILOCK_EXCL);

out:
	/* scrub teardown will unlock and release the inode */
	return error;
}

/*
 * Inode fork block mapping (BMBT) scrubber.
 * More complex than the others because we have to scrub
 * all the extents regardless of whether or not the fork
 * is in btree format.
 */

struct xchk_bmap_info {
	struct xfs_scrub	*sc;
	xfs_fileoff_t		lastoff;
	bool			is_rt;
	bool			is_shared;
	bool			was_loaded;
	int			whichfork;
};

/* Look for a corresponding rmap for this irec. */
static inline bool
xchk_bmap_get_rmap(
	struct xchk_bmap_info	*info,
	struct xfs_bmbt_irec	*irec,
	xfs_agblock_t		agbno,
	uint64_t		owner,
	struct xfs_rmap_irec	*rmap)
{
	xfs_fileoff_t		offset;
	unsigned int		rflags = 0;
	int			has_rmap;
	int			error;

	if (info->whichfork == XFS_ATTR_FORK)
		rflags |= XFS_RMAP_ATTR_FORK;

	/*
	 * CoW staging extents are owned (on disk) by the refcountbt, so
	 * their rmaps do not have offsets.
	 */
	if (info->whichfork == XFS_COW_FORK)
		offset = 0;
	else
		offset = irec->br_startoff;

	/*
	 * If the caller thinks this could be a shared bmbt extent (IOWs,
	 * any data fork extent of a reflink inode) then we have to use the
	 * range rmap lookup to make sure we get the correct owner/offset.
	 */
	if (info->is_shared) {
		error = xfs_rmap_lookup_le_range(info->sc->sa.rmap_cur, agbno,
				owner, offset, rflags, rmap, &has_rmap);
		if (!xchk_should_check_xref(info->sc, &error,
				&info->sc->sa.rmap_cur))
			return false;
		goto out;
	}

	/*
	 * Otherwise, use the (faster) regular lookup.
	 */
	error = xfs_rmap_lookup_le(info->sc->sa.rmap_cur, agbno, 0, owner,
			offset, rflags, &has_rmap);
	if (!xchk_should_check_xref(info->sc, &error,
			&info->sc->sa.rmap_cur))
		return false;
	if (!has_rmap)
		goto out;

	error = xfs_rmap_get_rec(info->sc->sa.rmap_cur, rmap, &has_rmap);
	if (!xchk_should_check_xref(info->sc, &error,
			&info->sc->sa.rmap_cur))
		return false;

out:
	if (!has_rmap)
		xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
			irec->br_startoff);
	return has_rmap;
}

/* Make sure that we have rmapbt records for this extent. */
STATIC void
xchk_bmap_xref_rmap(
	struct xchk_bmap_info	*info,
	struct xfs_bmbt_irec	*irec,
	xfs_agblock_t		agbno)
{
	struct xfs_rmap_irec	rmap;
	unsigned long long	rmap_end;
	uint64_t		owner;

	if (!info->sc->sa.rmap_cur || xchk_skip_xref(info->sc->sm))
		return;

	if (info->whichfork == XFS_COW_FORK)
		owner = XFS_RMAP_OWN_COW;
	else
		owner = info->sc->ip->i_ino;

	/* Find the rmap record for this irec. */
	if (!xchk_bmap_get_rmap(info, irec, agbno, owner, &rmap))
		return;

	/* Check the rmap. */
	rmap_end = (unsigned long long)rmap.rm_startblock + rmap.rm_blockcount;
	if (rmap.rm_startblock > agbno ||
	    agbno + irec->br_blockcount > rmap_end)
		xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);

	/*
	 * Check the logical offsets if applicable.  CoW staging extents
	 * don't track logical offsets since the mappings only exist in
	 * memory.
	 */
	if (info->whichfork != XFS_COW_FORK) {
		rmap_end = (unsigned long long)rmap.rm_offset +
				rmap.rm_blockcount;
		if (rmap.rm_offset > irec->br_startoff ||
		    irec->br_startoff + irec->br_blockcount > rmap_end)
			xchk_fblock_xref_set_corrupt(info->sc,
					info->whichfork, irec->br_startoff);
	}

	if (rmap.rm_owner != owner)
		xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);

	/*
	 * Check for discrepancies between the unwritten flag in the irec and
	 * the rmap.  Note that the (in-memory) CoW fork distinguishes between
	 * unwritten and written extents, but we don't track that in the rmap
	 * records because the blocks are owned (on-disk) by the refcountbt,
	 * which doesn't track unwritten state.
	 */
	if (owner != XFS_RMAP_OWN_COW &&
	    irec->br_state == XFS_EXT_UNWRITTEN &&
	    !(rmap.rm_flags & XFS_RMAP_UNWRITTEN))
		xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);

	if (info->whichfork == XFS_ATTR_FORK &&
	    !(rmap.rm_flags & XFS_RMAP_ATTR_FORK))
		xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);
	if (rmap.rm_flags & XFS_RMAP_BMBT_BLOCK)
		xchk_fblock_xref_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);
}

/* Cross-reference a single rtdev extent record. */
STATIC void
xchk_bmap_rt_iextent_xref(
	struct xfs_inode	*ip,
	struct xchk_bmap_info	*info,
	struct xfs_bmbt_irec	*irec)
{
	xchk_xref_is_used_rt_space(info->sc, irec->br_startblock,
			irec->br_blockcount);
}

/* Cross-reference a single datadev extent record. */
STATIC void
xchk_bmap_iextent_xref(
	struct xfs_inode	*ip,
	struct xchk_bmap_info	*info,
	struct xfs_bmbt_irec	*irec)
{
	struct xfs_mount	*mp = info->sc->mp;
	xfs_agnumber_t		agno;
	xfs_agblock_t		agbno;
	xfs_extlen_t		len;
	int			error;

	agno = XFS_FSB_TO_AGNO(mp, irec->br_startblock);
	agbno = XFS_FSB_TO_AGBNO(mp, irec->br_startblock);
	len = irec->br_blockcount;

	error = xchk_ag_init(info->sc, agno, &info->sc->sa);
	if (!xchk_fblock_process_error(info->sc, info->whichfork,
			irec->br_startoff, &error))
		return;

	xchk_xref_is_used_space(info->sc, agbno, len);
	xchk_xref_is_not_inode_chunk(info->sc, agbno, len);
	xchk_bmap_xref_rmap(info, irec, agbno);
	switch (info->whichfork) {
	case XFS_DATA_FORK:
		if (xfs_is_reflink_inode(info->sc->ip))
			break;
		/* fall through */
	case XFS_ATTR_FORK:
		xchk_xref_is_not_shared(info->sc, agbno,
				irec->br_blockcount);
		break;
	case XFS_COW_FORK:
		xchk_xref_is_cow_staging(info->sc, agbno,
				irec->br_blockcount);
		break;
	}

	xchk_ag_free(info->sc, &info->sc->sa);
}

/*
 * Directories and attr forks should never have blocks that can't be addressed
 * by a xfs_dablk_t.
 */
STATIC void
xchk_bmap_dirattr_extent(
	struct xfs_inode	*ip,
	struct xchk_bmap_info	*info,
	struct xfs_bmbt_irec	*irec)
{
	struct xfs_mount	*mp = ip->i_mount;
	xfs_fileoff_t		off;

	if (!S_ISDIR(VFS_I(ip)->i_mode) && info->whichfork != XFS_ATTR_FORK)
		return;

	if (!xfs_verify_dablk(mp, irec->br_startoff))
		xchk_fblock_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);

	off = irec->br_startoff + irec->br_blockcount - 1;
	if (!xfs_verify_dablk(mp, off))
		xchk_fblock_set_corrupt(info->sc, info->whichfork, off);
}

/* Scrub a single extent record. */
STATIC int
xchk_bmap_iextent(
	struct xfs_inode	*ip,
	struct xchk_bmap_info	*info,
	struct xfs_bmbt_irec	*irec)
{
	struct xfs_mount	*mp = info->sc->mp;
	xfs_filblks_t		end;
	int			error = 0;

	/*
	 * Check for out-of-order extents.  This record could have come
	 * from the incore list, for which there is no ordering check.
	 */
	if (irec->br_startoff < info->lastoff)
		xchk_fblock_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);

	xchk_bmap_dirattr_extent(ip, info, irec);

	/* There should never be a "hole" extent in either extent list. */
	if (irec->br_startblock == HOLESTARTBLOCK)
		xchk_fblock_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);

	/*
	 * Check for delalloc extents.  We never iterate the ones in the
	 * in-core extent scan, and we should never see these in the bmbt.
	 */
	if (isnullstartblock(irec->br_startblock))
		xchk_fblock_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);

	/* Make sure the extent points to a valid place. */
	if (irec->br_blockcount > MAXEXTLEN)
		xchk_fblock_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);
	if (irec->br_startblock + irec->br_blockcount <= irec->br_startblock)
		xchk_fblock_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);
	end = irec->br_startblock + irec->br_blockcount - 1;
	if (info->is_rt &&
	    (!xfs_verify_rtbno(mp, irec->br_startblock) ||
	     !xfs_verify_rtbno(mp, end)))
		xchk_fblock_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);
	if (!info->is_rt &&
	    (!xfs_verify_fsbno(mp, irec->br_startblock) ||
	     !xfs_verify_fsbno(mp, end) ||
	     XFS_FSB_TO_AGNO(mp, irec->br_startblock) !=
				XFS_FSB_TO_AGNO(mp, end)))
		xchk_fblock_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);

	/* We don't allow unwritten extents on attr forks. */
	if (irec->br_state == XFS_EXT_UNWRITTEN &&
	    info->whichfork == XFS_ATTR_FORK)
		xchk_fblock_set_corrupt(info->sc, info->whichfork,
				irec->br_startoff);

	if (info->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return 0;

	if (info->is_rt)
		xchk_bmap_rt_iextent_xref(ip, info, irec);
	else
		xchk_bmap_iextent_xref(ip, info, irec);

	info->lastoff = irec->br_startoff + irec->br_blockcount;
	return error;
}

/* Scrub a bmbt record. */
STATIC int
xchk_bmapbt_rec(
	struct xchk_btree	*bs,
	union xfs_btree_rec	*rec)
{
	struct xfs_bmbt_irec	irec;
	struct xfs_bmbt_irec	iext_irec;
	struct xfs_iext_cursor	icur;
	struct xchk_bmap_info	*info = bs->private;
	struct xfs_inode	*ip = bs->cur->bc_ino.ip;
	struct xfs_buf		*bp = NULL;
	struct xfs_btree_block	*block;
	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, info->whichfork);
	uint64_t		owner;
	int			i;

	/*
	 * Check the owners of the btree blocks up to the level below
	 * the root since the verifiers don't do that.
	 */
	if (xfs_sb_version_hascrc(&bs->cur->bc_mp->m_sb) &&
	    bs->cur->bc_ptrs[0] == 1) {
		for (i = 0; i < bs->cur->bc_nlevels - 1; i++) {
			block = xfs_btree_get_block(bs->cur, i, &bp);
			owner = be64_to_cpu(block->bb_u.l.bb_owner);
			if (owner != ip->i_ino)
				xchk_fblock_set_corrupt(bs->sc,
						info->whichfork, 0);
		}
	}

	/*
	 * Check that the incore extent tree contains an extent that matches
	 * this one exactly.  We validate those cached bmaps later, so we don't
	 * need to check them here.  If the incore extent tree was just loaded
	 * from disk by the scrubber, we assume that its contents match what's
	 * on disk (we still hold the ILOCK) and skip the equivalence check.
	 */
	if (!info->was_loaded)
		return 0;

	xfs_bmbt_disk_get_all(&rec->bmbt, &irec);
	if (!xfs_iext_lookup_extent(ip, ifp, irec.br_startoff, &icur,
				&iext_irec) ||
	    irec.br_startoff != iext_irec.br_startoff ||
	    irec.br_startblock != iext_irec.br_startblock ||
	    irec.br_blockcount != iext_irec.br_blockcount ||
	    irec.br_state != iext_irec.br_state)
		xchk_fblock_set_corrupt(bs->sc, info->whichfork,
				irec.br_startoff);
	return 0;
}

/* Scan the btree records. */
STATIC int
xchk_bmap_btree(
	struct xfs_scrub	*sc,
	int			whichfork,
	struct xchk_bmap_info	*info)
{
	struct xfs_owner_info	oinfo;
	struct xfs_ifork	*ifp = XFS_IFORK_PTR(sc->ip, whichfork);
	struct xfs_mount	*mp = sc->mp;
	struct xfs_inode	*ip = sc->ip;
	struct xfs_btree_cur	*cur;
	int			error;

	/* Load the incore bmap cache if it's not loaded. */
	info->was_loaded = ifp->if_flags & XFS_IFEXTENTS;
	if (!info->was_loaded) {
		error = xfs_iread_extents(sc->tp, ip, whichfork);
		if (!xchk_fblock_process_error(sc, whichfork, 0, &error))
			goto out;
	}

	/* Check the btree structure. */
	cur = xfs_bmbt_init_cursor(mp, sc->tp, ip, whichfork);
	xfs_rmap_ino_bmbt_owner(&oinfo, ip->i_ino, whichfork);
	error = xchk_btree(sc, cur, xchk_bmapbt_rec, &oinfo, info);
	xfs_btree_del_cursor(cur, error);
out:
	return error;
}

struct xchk_bmap_check_rmap_info {
	struct xfs_scrub	*sc;
	int			whichfork;
	struct xfs_iext_cursor	icur;
};

/* Can we find bmaps that fit this rmap? */
STATIC int
xchk_bmap_check_rmap(
	struct xfs_btree_cur		*cur,
	struct xfs_rmap_irec		*rec,
	void				*priv)
{
	struct xfs_bmbt_irec		irec;
	struct xchk_bmap_check_rmap_info	*sbcri = priv;
	struct xfs_ifork		*ifp;
	struct xfs_scrub		*sc = sbcri->sc;
	bool				have_map;

	/* Is this even the right fork? */
	if (rec->rm_owner != sc->ip->i_ino)
		return 0;
	if ((sbcri->whichfork == XFS_ATTR_FORK) ^
	    !!(rec->rm_flags & XFS_RMAP_ATTR_FORK))
		return 0;
	if (rec->rm_flags & XFS_RMAP_BMBT_BLOCK)
		return 0;

	/* Now look up the bmbt record. */
	ifp = XFS_IFORK_PTR(sc->ip, sbcri->whichfork);
	if (!ifp) {
		xchk_fblock_set_corrupt(sc, sbcri->whichfork,
				rec->rm_offset);
		goto out;
	}
	have_map = xfs_iext_lookup_extent(sc->ip, ifp, rec->rm_offset,
			&sbcri->icur, &irec);
	if (!have_map)
		xchk_fblock_set_corrupt(sc, sbcri->whichfork,
				rec->rm_offset);
	/*
	 * bmap extent record lengths are constrained to 2^21 blocks in length
	 * because of space constraints in the on-disk metadata structure.
	 * However, rmap extent record lengths are constrained only by AG
	 * length, so we have to loop through the bmbt to make sure that the
	 * entire rmap is covered by bmbt records.
	 */
	while (have_map) {
		if (irec.br_startoff != rec->rm_offset)
			xchk_fblock_set_corrupt(sc, sbcri->whichfork,
					rec->rm_offset);
		if (irec.br_startblock != XFS_AGB_TO_FSB(sc->mp,
				cur->bc_ag.agno, rec->rm_startblock))
			xchk_fblock_set_corrupt(sc, sbcri->whichfork,
					rec->rm_offset);
		if (irec.br_blockcount > rec->rm_blockcount)
			xchk_fblock_set_corrupt(sc, sbcri->whichfork,
					rec->rm_offset);
		if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
			break;
		rec->rm_startblock += irec.br_blockcount;
		rec->rm_offset += irec.br_blockcount;
		rec->rm_blockcount -= irec.br_blockcount;
		if (rec->rm_blockcount == 0)
			break;
		have_map = xfs_iext_next_extent(ifp, &sbcri->icur, &irec);
		if (!have_map)
			xchk_fblock_set_corrupt(sc, sbcri->whichfork,
					rec->rm_offset);
	}

out:
	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		return -ECANCELED;
	return 0;
}

/* Make sure each rmap has a corresponding bmbt entry. */
STATIC int
xchk_bmap_check_ag_rmaps(
	struct xfs_scrub		*sc,
	int				whichfork,
	xfs_agnumber_t			agno)
{
	struct xchk_bmap_check_rmap_info	sbcri;
	struct xfs_btree_cur		*cur;
	struct xfs_buf			*agf;
	int				error;

	error = xfs_alloc_read_agf(sc->mp, sc->tp, agno, 0, &agf);
	if (error)
		return error;

	cur = xfs_rmapbt_init_cursor(sc->mp, sc->tp, agf, agno);
	if (!cur) {
		error = -ENOMEM;
		goto out_agf;
	}

	sbcri.sc = sc;
	sbcri.whichfork = whichfork;
	error = xfs_rmap_query_all(cur, xchk_bmap_check_rmap, &sbcri);
	if (error == -ECANCELED)
		error = 0;

	xfs_btree_del_cursor(cur, error);
out_agf:
	xfs_trans_brelse(sc->tp, agf);
	return error;
}

/* Make sure each rmap has a corresponding bmbt entry. */
STATIC int
xchk_bmap_check_rmaps(
	struct xfs_scrub	*sc,
	int			whichfork)
{
	struct xfs_ifork	*ifp = XFS_IFORK_PTR(sc->ip, whichfork);
	xfs_agnumber_t		agno;
	bool			zero_size;
	int			error;

	if (!xfs_sb_version_hasrmapbt(&sc->mp->m_sb) ||
	    whichfork == XFS_COW_FORK ||
	    (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
		return 0;

	/* Don't support realtime rmap checks yet. */
	if (XFS_IS_REALTIME_INODE(sc->ip) && whichfork == XFS_DATA_FORK)
		return 0;

	ASSERT(XFS_IFORK_PTR(sc->ip, whichfork) != NULL);

	/*
	 * Only do this for complex maps that are in btree format, or for
	 * situations where we would seem to have a size but zero extents.
	 * The inode repair code can zap broken iforks, which means we have
	 * to flag this bmap as corrupt if there are rmaps that need to be
	 * reattached.
	 */

	if (whichfork == XFS_DATA_FORK)
		zero_size = i_size_read(VFS_I(sc->ip)) == 0;
	else
		zero_size = false;

	if (ifp->if_format != XFS_DINODE_FMT_BTREE &&
	    (zero_size || ifp->if_nextents > 0))
		return 0;

	for (agno = 0; agno < sc->mp->m_sb.sb_agcount; agno++) {
		error = xchk_bmap_check_ag_rmaps(sc, whichfork, agno);
		if (error)
			return error;
		if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
			break;
	}

	return 0;
}

/*
 * Scrub an inode fork's block mappings.
 *
 * First we scan every record in every btree block, if applicable.
 * Then we unconditionally scan the incore extent cache.
 */
STATIC int
xchk_bmap(
	struct xfs_scrub	*sc,
	int			whichfork)
{
	struct xfs_bmbt_irec	irec;
	struct xchk_bmap_info	info = { NULL };
	struct xfs_mount	*mp = sc->mp;
	struct xfs_inode	*ip = sc->ip;
	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
	xfs_fileoff_t		endoff;
	struct xfs_iext_cursor	icur;
	int			error = 0;

	/* Non-existent forks can be ignored. */
	if (!ifp)
		goto out;

	info.is_rt = whichfork == XFS_DATA_FORK && XFS_IS_REALTIME_INODE(ip);
	info.whichfork = whichfork;
	info.is_shared = whichfork == XFS_DATA_FORK && xfs_is_reflink_inode(ip);
	info.sc = sc;

	switch (whichfork) {
	case XFS_COW_FORK:
		/* No CoW forks on non-reflink inodes/filesystems. */
		if (!xfs_is_reflink_inode(ip)) {
			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
			goto out;
		}
		break;
	case XFS_ATTR_FORK:
		if (!xfs_sb_version_hasattr(&mp->m_sb) &&
		    !xfs_sb_version_hasattr2(&mp->m_sb))
			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
		break;
	default:
		ASSERT(whichfork == XFS_DATA_FORK);
		break;
	}

	/* Check the fork values */
	switch (ifp->if_format) {
	case XFS_DINODE_FMT_UUID:
	case XFS_DINODE_FMT_DEV:
	case XFS_DINODE_FMT_LOCAL:
		/* No mappings to check. */
		goto out;
	case XFS_DINODE_FMT_EXTENTS:
		if (!(ifp->if_flags & XFS_IFEXTENTS)) {
			xchk_fblock_set_corrupt(sc, whichfork, 0);
			goto out;
		}
		break;
	case XFS_DINODE_FMT_BTREE:
		if (whichfork == XFS_COW_FORK) {
			xchk_fblock_set_corrupt(sc, whichfork, 0);
			goto out;
		}

		error = xchk_bmap_btree(sc, whichfork, &info);
		if (error)
			goto out;
		break;
	default:
		xchk_fblock_set_corrupt(sc, whichfork, 0);
		goto out;
	}

	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
		goto out;

	/* Find the offset of the last extent in the mapping. */
	error = xfs_bmap_last_offset(ip, &endoff, whichfork);
	if (!xchk_fblock_process_error(sc, whichfork, 0, &error))
		goto out;

	/* Scrub extent records. */
	info.lastoff = 0;
	ifp = XFS_IFORK_PTR(ip, whichfork);
	for_each_xfs_iext(ifp, &icur, &irec) {
		if (xchk_should_terminate(sc, &error) ||
		    (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
			goto out;
		if (isnullstartblock(irec.br_startblock))
			continue;
		if (irec.br_startoff >= endoff) {
			xchk_fblock_set_corrupt(sc, whichfork,
					irec.br_startoff);
			goto out;
		}
		error = xchk_bmap_iextent(ip, &info, &irec);
		if (error)
			goto out;
	}

	error = xchk_bmap_check_rmaps(sc, whichfork);
	if (!xchk_fblock_xref_process_error(sc, whichfork, 0, &error))
		goto out;
out:
	return error;
}

/* Scrub an inode's data fork. */
int
xchk_bmap_data(
	struct xfs_scrub	*sc)
{
	return xchk_bmap(sc, XFS_DATA_FORK);
}

/* Scrub an inode's attr fork. */
int
xchk_bmap_attr(
	struct xfs_scrub	*sc)
{
	return xchk_bmap(sc, XFS_ATTR_FORK);
}

/* Scrub an inode's CoW fork. */
int
xchk_bmap_cow(
	struct xfs_scrub	*sc)
{
	if (!xfs_is_reflink_inode(sc->ip))
		return -ENOENT;

	return xchk_bmap(sc, XFS_COW_FORK);
}