summaryrefslogtreecommitdiff
path: root/fs/xfs/scrub/cow_repair.c
blob: 1e82c727af8ed52e427a6060ecb2cbdb1b328c31 (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2022-2023 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <djwong@kernel.org>
 */
#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_defer.h"
#include "xfs_btree.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_inode.h"
#include "xfs_inode_fork.h"
#include "xfs_alloc.h"
#include "xfs_bmap.h"
#include "xfs_rmap.h"
#include "xfs_refcount.h"
#include "xfs_quota.h"
#include "xfs_ialloc.h"
#include "xfs_ag.h"
#include "xfs_error.h"
#include "xfs_errortag.h"
#include "xfs_icache.h"
#include "xfs_refcount_btree.h"
#include "scrub/xfs_scrub.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/trace.h"
#include "scrub/repair.h"
#include "scrub/bitmap.h"
#include "scrub/off_bitmap.h"
#include "scrub/fsb_bitmap.h"
#include "scrub/reap.h"

/*
 * CoW Fork Mapping Repair
 * =======================
 *
 * Although CoW staging extents are owned by incore CoW inode forks, on disk
 * they are owned by the refcount btree.  The ondisk metadata does not record
 * any ownership information, which limits what we can do to repair the
 * mappings in the CoW fork.  At most, we can replace ifork mappings that lack
 * an entry in the refcount btree or are described by a reverse mapping record
 * whose owner is not OWN_COW.
 *
 * Replacing extents is also tricky -- we can't touch written CoW fork extents
 * since they are undergoing writeback, and delalloc extents do not require
 * repair since they only exist incore.  Hence the most we can do is find the
 * bad parts of unwritten mappings, allocate a replacement set of blocks, and
 * replace the incore mapping.  We use the regular reaping process to unmap
 * or free the discarded blocks, as appropriate.
 */
struct xrep_cow {
	struct xfs_scrub	*sc;

	/* Bitmap of file offset ranges that need replacing. */
	struct xoff_bitmap	bad_fileoffs;

	/* Bitmap of fsblocks that were removed from the CoW fork. */
	struct xfsb_bitmap	old_cowfork_fsblocks;

	/* CoW fork mappings used to scan for bad CoW staging extents. */
	struct xfs_bmbt_irec	irec;

	/* refcount btree block number of irec.br_startblock */
	unsigned int		irec_startbno;

	/* refcount btree block number of the next refcount record we expect */
	unsigned int		next_bno;
};

/* CoW staging extent. */
struct xrep_cow_extent {
	xfs_fsblock_t		fsbno;
	xfs_extlen_t		len;
};

/*
 * Mark the part of the file range that corresponds to the given physical
 * space.  Caller must ensure that the physical range is within xc->irec.
 */
STATIC int
xrep_cow_mark_file_range(
	struct xrep_cow		*xc,
	xfs_fsblock_t		startblock,
	xfs_filblks_t		blockcount)
{
	xfs_fileoff_t		startoff;

	startoff = xc->irec.br_startoff +
				(startblock - xc->irec.br_startblock);

	trace_xrep_cow_mark_file_range(xc->sc->ip, startblock, startoff,
			blockcount);

	return xoff_bitmap_set(&xc->bad_fileoffs, startoff, blockcount);
}

/*
 * Trim @src to fit within the CoW fork mapping being examined, and put the
 * result in @dst.
 */
static inline void
xrep_cow_trim_refcount(
	struct xrep_cow			*xc,
	struct xfs_refcount_irec	*dst,
	const struct xfs_refcount_irec	*src)
{
	unsigned int			adj;

	memcpy(dst, src, sizeof(*dst));

	if (dst->rc_startblock < xc->irec_startbno) {
		adj = xc->irec_startbno - dst->rc_startblock;
		dst->rc_blockcount -= adj;
		dst->rc_startblock += adj;
	}

	if (dst->rc_startblock + dst->rc_blockcount >
	    xc->irec_startbno + xc->irec.br_blockcount) {
		adj = (dst->rc_startblock + dst->rc_blockcount) -
		      (xc->irec_startbno + xc->irec.br_blockcount);
		dst->rc_blockcount -= adj;
	}
}

/* Mark any shared CoW staging extents. */
STATIC int
xrep_cow_mark_shared_staging(
	struct xfs_btree_cur		*cur,
	const struct xfs_refcount_irec	*rec,
	void				*priv)
{
	struct xrep_cow			*xc = priv;
	struct xfs_refcount_irec	rrec;
	xfs_fsblock_t			fsbno;

	if (!xfs_refcount_check_domain(rec) ||
	    rec->rc_domain != XFS_REFC_DOMAIN_SHARED)
		return -EFSCORRUPTED;

	xrep_cow_trim_refcount(xc, &rrec, rec);

	fsbno = XFS_AGB_TO_FSB(xc->sc->mp, cur->bc_ag.pag->pag_agno,
			rrec.rc_startblock);
	return xrep_cow_mark_file_range(xc, fsbno, rrec.rc_blockcount);
}

/*
 * Mark any portion of the CoW fork file offset range where there is not a CoW
 * staging extent record in the refcountbt, and keep a record of where we did
 * find correct refcountbt records.  Staging records are always cleaned out at
 * mount time, so any two inodes trying to map the same staging area would have
 * already taken the fs down due to refcount btree verifier errors.  Hence this
 * inode should be the sole creator of the staging extent records ondisk.
 */
STATIC int
xrep_cow_mark_missing_staging(
	struct xfs_btree_cur		*cur,
	const struct xfs_refcount_irec	*rec,
	void				*priv)
{
	struct xrep_cow			*xc = priv;
	struct xfs_refcount_irec	rrec;
	int				error;

	if (!xfs_refcount_check_domain(rec) ||
	    rec->rc_domain != XFS_REFC_DOMAIN_COW)
		return -EFSCORRUPTED;

	xrep_cow_trim_refcount(xc, &rrec, rec);

	if (xc->next_bno >= rrec.rc_startblock)
		goto next;

	error = xrep_cow_mark_file_range(xc,
			XFS_AGB_TO_FSB(xc->sc->mp, cur->bc_ag.pag->pag_agno,
				       xc->next_bno),
			rrec.rc_startblock - xc->next_bno);
	if (error)
		return error;

next:
	xc->next_bno = rrec.rc_startblock + rrec.rc_blockcount;
	return 0;
}

/*
 * Mark any area that does not correspond to a CoW staging rmap.  These are
 * cross-linked areas that must be avoided.
 */
STATIC int
xrep_cow_mark_missing_staging_rmap(
	struct xfs_btree_cur		*cur,
	const struct xfs_rmap_irec	*rec,
	void				*priv)
{
	struct xrep_cow			*xc = priv;
	xfs_fsblock_t			fsbno;
	xfs_agblock_t			rec_bno;
	xfs_extlen_t			rec_len;
	unsigned int			adj;

	if (rec->rm_owner == XFS_RMAP_OWN_COW)
		return 0;

	rec_bno = rec->rm_startblock;
	rec_len = rec->rm_blockcount;
	if (rec_bno < xc->irec_startbno) {
		adj = xc->irec_startbno - rec_bno;
		rec_len -= adj;
		rec_bno += adj;
	}

	if (rec_bno + rec_len > xc->irec_startbno + xc->irec.br_blockcount) {
		adj = (rec_bno + rec_len) -
		      (xc->irec_startbno + xc->irec.br_blockcount);
		rec_len -= adj;
	}

	fsbno = XFS_AGB_TO_FSB(xc->sc->mp, cur->bc_ag.pag->pag_agno, rec_bno);
	return xrep_cow_mark_file_range(xc, fsbno, rec_len);
}

/*
 * Find any part of the CoW fork mapping that isn't a single-owner CoW staging
 * extent and mark the corresponding part of the file range in the bitmap.
 */
STATIC int
xrep_cow_find_bad(
	struct xrep_cow			*xc)
{
	struct xfs_refcount_irec	rc_low = { 0 };
	struct xfs_refcount_irec	rc_high = { 0 };
	struct xfs_rmap_irec		rm_low = { 0 };
	struct xfs_rmap_irec		rm_high = { 0 };
	struct xfs_perag		*pag;
	struct xfs_scrub		*sc = xc->sc;
	xfs_agnumber_t			agno;
	int				error;

	agno = XFS_FSB_TO_AGNO(sc->mp, xc->irec.br_startblock);
	xc->irec_startbno = XFS_FSB_TO_AGBNO(sc->mp, xc->irec.br_startblock);

	pag = xfs_perag_get(sc->mp, agno);
	if (!pag)
		return -EFSCORRUPTED;

	error = xrep_ag_init(sc, pag, &sc->sa);
	if (error)
		goto out_pag;

	/* Mark any CoW fork extents that are shared. */
	rc_low.rc_startblock = xc->irec_startbno;
	rc_high.rc_startblock = xc->irec_startbno + xc->irec.br_blockcount - 1;
	rc_low.rc_domain = rc_high.rc_domain = XFS_REFC_DOMAIN_SHARED;
	error = xfs_refcount_query_range(sc->sa.refc_cur, &rc_low, &rc_high,
			xrep_cow_mark_shared_staging, xc);
	if (error)
		goto out_sa;

	/* Make sure there are CoW staging extents for the whole mapping. */
	rc_low.rc_startblock = xc->irec_startbno;
	rc_high.rc_startblock = xc->irec_startbno + xc->irec.br_blockcount - 1;
	rc_low.rc_domain = rc_high.rc_domain = XFS_REFC_DOMAIN_COW;
	xc->next_bno = xc->irec_startbno;
	error = xfs_refcount_query_range(sc->sa.refc_cur, &rc_low, &rc_high,
			xrep_cow_mark_missing_staging, xc);
	if (error)
		goto out_sa;

	if (xc->next_bno < xc->irec_startbno + xc->irec.br_blockcount) {
		error = xrep_cow_mark_file_range(xc,
				XFS_AGB_TO_FSB(sc->mp, pag->pag_agno,
					       xc->next_bno),
				xc->irec_startbno + xc->irec.br_blockcount -
				xc->next_bno);
		if (error)
			goto out_sa;
	}

	/* Mark any area has an rmap that isn't a COW staging extent. */
	rm_low.rm_startblock = xc->irec_startbno;
	memset(&rm_high, 0xFF, sizeof(rm_high));
	rm_high.rm_startblock = xc->irec_startbno + xc->irec.br_blockcount - 1;
	error = xfs_rmap_query_range(sc->sa.rmap_cur, &rm_low, &rm_high,
			xrep_cow_mark_missing_staging_rmap, xc);
	if (error)
		goto out_sa;

	/*
	 * If userspace is forcing us to rebuild the CoW fork or someone turned
	 * on the debugging knob, replace everything in the CoW fork.
	 */
	if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD) ||
	    XFS_TEST_ERROR(false, sc->mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR)) {
		error = xrep_cow_mark_file_range(xc, xc->irec.br_startblock,
				xc->irec.br_blockcount);
		if (error)
			return error;
	}

out_sa:
	xchk_ag_free(sc, &sc->sa);
out_pag:
	xfs_perag_put(pag);
	return 0;
}

/*
 * Allocate a replacement CoW staging extent of up to the given number of
 * blocks, and fill out the mapping.
 */
STATIC int
xrep_cow_alloc(
	struct xfs_scrub	*sc,
	xfs_extlen_t		maxlen,
	struct xrep_cow_extent	*repl)
{
	struct xfs_alloc_arg	args = {
		.tp		= sc->tp,
		.mp		= sc->mp,
		.oinfo		= XFS_RMAP_OINFO_SKIP_UPDATE,
		.minlen		= 1,
		.maxlen		= maxlen,
		.prod		= 1,
		.resv		= XFS_AG_RESV_NONE,
		.datatype	= XFS_ALLOC_USERDATA,
	};
	int			error;

	error = xfs_trans_reserve_more(sc->tp, maxlen, 0);
	if (error)
		return error;

	error = xfs_alloc_vextent_start_ag(&args,
			XFS_INO_TO_FSB(sc->mp, sc->ip->i_ino));
	if (error)
		return error;
	if (args.fsbno == NULLFSBLOCK)
		return -ENOSPC;

	xfs_refcount_alloc_cow_extent(sc->tp, args.fsbno, args.len);

	repl->fsbno = args.fsbno;
	repl->len = args.len;
	return 0;
}

/*
 * Look up the current CoW fork mapping so that we only allocate enough to
 * replace a single mapping.  If we don't find a mapping that covers the start
 * of the file range, or we find a delalloc or written extent, something is
 * seriously wrong, since we didn't drop the ILOCK.
 */
static inline int
xrep_cow_find_mapping(
	struct xrep_cow		*xc,
	struct xfs_iext_cursor	*icur,
	xfs_fileoff_t		startoff,
	struct xfs_bmbt_irec	*got)
{
	struct xfs_inode	*ip = xc->sc->ip;
	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);

	if (!xfs_iext_lookup_extent(ip, ifp, startoff, icur, got))
		goto bad;

	if (got->br_startoff > startoff)
		goto bad;

	if (got->br_blockcount == 0)
		goto bad;

	if (isnullstartblock(got->br_startblock))
		goto bad;

	if (xfs_bmap_is_written_extent(got))
		goto bad;

	return 0;
bad:
	ASSERT(0);
	return -EFSCORRUPTED;
}

#define REPLACE_LEFT_SIDE	(1U << 0)
#define REPLACE_RIGHT_SIDE	(1U << 1)

/*
 * Given a CoW fork mapping @got and a replacement mapping @repl, remap the
 * beginning of @got with the space described by @rep.
 */
static inline void
xrep_cow_replace_mapping(
	struct xfs_inode		*ip,
	struct xfs_iext_cursor		*icur,
	const struct xfs_bmbt_irec	*got,
	const struct xrep_cow_extent	*repl)
{
	struct xfs_bmbt_irec		new = *got; /* struct copy */

	ASSERT(repl->len > 0);
	ASSERT(!isnullstartblock(got->br_startblock));

	trace_xrep_cow_replace_mapping(ip, got, repl->fsbno, repl->len);

	if (got->br_blockcount == repl->len) {
		/*
		 * The new extent is a complete replacement for the existing
		 * extent.  Update the COW fork record.
		 */
		new.br_startblock = repl->fsbno;
		xfs_iext_update_extent(ip, BMAP_COWFORK, icur, &new);
		return;
	}

	/*
	 * The new extent can replace the beginning of the COW fork record.
	 * Move the left side of @got upwards, then insert the new record.
	 */
	new.br_startoff += repl->len;
	new.br_startblock += repl->len;
	new.br_blockcount -= repl->len;
	xfs_iext_update_extent(ip, BMAP_COWFORK, icur, &new);

	new.br_startoff = got->br_startoff;
	new.br_startblock = repl->fsbno;
	new.br_blockcount = repl->len;
	xfs_iext_insert(ip, icur, &new, BMAP_COWFORK);
}

/*
 * Replace the unwritten CoW staging extent backing the given file range with a
 * new space extent that isn't as problematic.
 */
STATIC int
xrep_cow_replace_range(
	struct xrep_cow		*xc,
	xfs_fileoff_t		startoff,
	xfs_extlen_t		*blockcount)
{
	struct xfs_iext_cursor	icur;
	struct xrep_cow_extent	repl;
	struct xfs_bmbt_irec	got;
	struct xfs_scrub	*sc = xc->sc;
	xfs_fileoff_t		nextoff;
	xfs_extlen_t		alloc_len;
	int			error;

	/*
	 * Put the existing CoW fork mapping in @got.  If @got ends before
	 * @rep, truncate @rep so we only replace one extent mapping at a time.
	 */
	error = xrep_cow_find_mapping(xc, &icur, startoff, &got);
	if (error)
		return error;
	nextoff = min(startoff + *blockcount,
		      got.br_startoff + got.br_blockcount);

	/*
	 * Allocate a replacement extent.  If we don't fill all the blocks,
	 * shorten the quantity that will be deleted in this step.
	 */
	alloc_len = min_t(xfs_fileoff_t, XFS_MAX_BMBT_EXTLEN,
			  nextoff - startoff);
	error = xrep_cow_alloc(sc, alloc_len, &repl);
	if (error)
		return error;

	/*
	 * Replace the old mapping with the new one, and commit the metadata
	 * changes made so far.
	 */
	xrep_cow_replace_mapping(sc->ip, &icur, &got, &repl);

	xfs_inode_set_cowblocks_tag(sc->ip);
	error = xfs_defer_finish(&sc->tp);
	if (error)
		return error;

	/* Note the old CoW staging extents; we'll reap them all later. */
	error = xfsb_bitmap_set(&xc->old_cowfork_fsblocks, got.br_startblock,
			repl.len);
	if (error)
		return error;

	*blockcount = repl.len;
	return 0;
}

/*
 * Replace a bad part of an unwritten CoW staging extent with a fresh delalloc
 * reservation.
 */
STATIC int
xrep_cow_replace(
	uint64_t		startoff,
	uint64_t		blockcount,
	void			*priv)
{
	struct xrep_cow		*xc = priv;
	int			error = 0;

	while (blockcount > 0) {
		xfs_extlen_t	len = min_t(xfs_filblks_t, blockcount,
					    XFS_MAX_BMBT_EXTLEN);

		error = xrep_cow_replace_range(xc, startoff, &len);
		if (error)
			break;

		blockcount -= len;
		startoff += len;
	}

	return error;
}

/*
 * Repair an inode's CoW fork.  The CoW fork is an in-core structure, so
 * there's no btree to rebuid.  Instead, we replace any mappings that are
 * cross-linked or lack ondisk CoW fork records in the refcount btree.
 */
int
xrep_bmap_cow(
	struct xfs_scrub	*sc)
{
	struct xrep_cow		*xc;
	struct xfs_iext_cursor	icur;
	struct xfs_ifork	*ifp = xfs_ifork_ptr(sc->ip, XFS_COW_FORK);
	int			error;

	if (!xfs_has_rmapbt(sc->mp) || !xfs_has_reflink(sc->mp))
		return -EOPNOTSUPP;

	if (!ifp)
		return 0;

	/* realtime files aren't supported yet */
	if (XFS_IS_REALTIME_INODE(sc->ip))
		return -EOPNOTSUPP;

	/*
	 * If we're somehow not in extents format, then reinitialize it to
	 * an empty extent mapping fork and exit.
	 */
	if (ifp->if_format != XFS_DINODE_FMT_EXTENTS) {
		ifp->if_format = XFS_DINODE_FMT_EXTENTS;
		ifp->if_nextents = 0;
		return 0;
	}

	xc = kzalloc(sizeof(struct xrep_cow), XCHK_GFP_FLAGS);
	if (!xc)
		return -ENOMEM;

	xfs_trans_ijoin(sc->tp, sc->ip, 0);

	xc->sc = sc;
	xoff_bitmap_init(&xc->bad_fileoffs);
	xfsb_bitmap_init(&xc->old_cowfork_fsblocks);

	for_each_xfs_iext(ifp, &icur, &xc->irec) {
		if (xchk_should_terminate(sc, &error))
			goto out_bitmap;

		/*
		 * delalloc reservations only exist incore, so there is no
		 * ondisk metadata that we can examine.  Hence we leave them
		 * alone.
		 */
		if (isnullstartblock(xc->irec.br_startblock))
			continue;

		/*
		 * COW fork extents are only in the written state if writeback
		 * is actively writing to disk.  We cannot restart the write
		 * at a different disk address since we've already issued the
		 * IO, so we leave these alone and hope for the best.
		 */
		if (xfs_bmap_is_written_extent(&xc->irec))
			continue;

		error = xrep_cow_find_bad(xc);
		if (error)
			goto out_bitmap;
	}

	/* Replace any bad unwritten mappings with fresh reservations. */
	error = xoff_bitmap_walk(&xc->bad_fileoffs, xrep_cow_replace, xc);
	if (error)
		goto out_bitmap;

	/*
	 * Reap as many of the old CoW blocks as we can.  They are owned ondisk
	 * by the refcount btree, not the inode, so it is correct to treat them
	 * like inode metadata.
	 */
	error = xrep_reap_fsblocks(sc, &xc->old_cowfork_fsblocks,
			&XFS_RMAP_OINFO_COW);
	if (error)
		goto out_bitmap;

out_bitmap:
	xfsb_bitmap_destroy(&xc->old_cowfork_fsblocks);
	xoff_bitmap_destroy(&xc->bad_fileoffs);
	kmem_free(xc);
	return error;
}