summaryrefslogtreecommitdiff
path: root/fs/ubifs/commit.c
blob: b148fbc80f8d1eb71ccc3a9b0f6a52b761fedab2 (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
/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * 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
 *
 * Authors: Adrian Hunter
 *          Artem Bityutskiy (Битюцкий Артём)
 */

/*
 * This file implements functions that manage the running of the commit process.
 * Each affected module has its own functions to accomplish their part in the
 * commit and those functions are called here.
 *
 * The commit is the process whereby all updates to the index and LEB properties
 * are written out together and the journal becomes empty. This keeps the
 * file system consistent - at all times the state can be recreated by reading
 * the index and LEB properties and then replaying the journal.
 *
 * The commit is split into two parts named "commit start" and "commit end".
 * During commit start, the commit process has exclusive access to the journal
 * by holding the commit semaphore down for writing. As few I/O operations as
 * possible are performed during commit start, instead the nodes that are to be
 * written are merely identified. During commit end, the commit semaphore is no
 * longer held and the journal is again in operation, allowing users to continue
 * to use the file system while the bulk of the commit I/O is performed. The
 * purpose of this two-step approach is to prevent the commit from causing any
 * latency blips. Note that in any case, the commit does not prevent lookups
 * (as permitted by the TNC mutex), or access to VFS data structures e.g. page
 * cache.
 */

#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/slab.h>
#include "ubifs.h"

/*
 * nothing_to_commit - check if there is nothing to commit.
 * @c: UBIFS file-system description object
 *
 * This is a helper function which checks if there is anything to commit. It is
 * used as an optimization to avoid starting the commit if it is not really
 * necessary. Indeed, the commit operation always assumes flash I/O (e.g.,
 * writing the commit start node to the log), and it is better to avoid doing
 * this unnecessarily. E.g., 'ubifs_sync_fs()' runs the commit, but if there is
 * nothing to commit, it is more optimal to avoid any flash I/O.
 *
 * This function has to be called with @c->commit_sem locked for writing -
 * this function does not take LPT/TNC locks because the @c->commit_sem
 * guarantees that we have exclusive access to the TNC and LPT data structures.
 *
 * This function returns %1 if there is nothing to commit and %0 otherwise.
 */
static int nothing_to_commit(struct ubifs_info *c)
{
	/*
	 * During mounting or remounting from R/O mode to R/W mode we may
	 * commit for various recovery-related reasons.
	 */
	if (c->mounting || c->remounting_rw)
		return 0;

	/*
	 * If the root TNC node is dirty, we definitely have something to
	 * commit.
	 */
	if (c->zroot.znode && test_bit(DIRTY_ZNODE, &c->zroot.znode->flags))
		return 0;

	/*
	 * Even though the TNC is clean, the LPT tree may have dirty nodes. For
	 * example, this may happen if the budgeting subsystem invoked GC to
	 * make some free space, and the GC found an LEB with only dirty and
	 * free space. In this case GC would just change the lprops of this
	 * LEB (by turning all space into free space) and unmap it.
	 */
	if (c->nroot && test_bit(DIRTY_CNODE, &c->nroot->flags))
		return 0;

	ubifs_assert(atomic_long_read(&c->dirty_zn_cnt) == 0);
	ubifs_assert(c->dirty_pn_cnt == 0);
	ubifs_assert(c->dirty_nn_cnt == 0);

	return 1;
}

/**
 * do_commit - commit the journal.
 * @c: UBIFS file-system description object
 *
 * This function implements UBIFS commit. It has to be called with commit lock
 * locked. Returns zero in case of success and a negative error code in case of
 * failure.
 */
static int do_commit(struct ubifs_info *c)
{
	int err, new_ltail_lnum, old_ltail_lnum, i;
	struct ubifs_zbranch zroot;
	struct ubifs_lp_stats lst;

	dbg_cmt("start");
	ubifs_assert(!c->ro_media && !c->ro_mount);

	if (c->ro_error) {
		err = -EROFS;
		goto out_up;
	}

	if (nothing_to_commit(c)) {
		up_write(&c->commit_sem);
		err = 0;
		goto out_cancel;
	}

	/* Sync all write buffers (necessary for recovery) */
	for (i = 0; i < c->jhead_cnt; i++) {
		err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
		if (err)
			goto out_up;
	}

	c->cmt_no += 1;
	err = ubifs_gc_start_commit(c);
	if (err)
		goto out_up;
	err = dbg_check_lprops(c);
	if (err)
		goto out_up;
	err = ubifs_log_start_commit(c, &new_ltail_lnum);
	if (err)
		goto out_up;
	err = ubifs_tnc_start_commit(c, &zroot);
	if (err)
		goto out_up;
	err = ubifs_lpt_start_commit(c);
	if (err)
		goto out_up;
	err = ubifs_orphan_start_commit(c);
	if (err)
		goto out_up;

	ubifs_get_lp_stats(c, &lst);

	up_write(&c->commit_sem);

	err = ubifs_tnc_end_commit(c);
	if (err)
		goto out;
	err = ubifs_lpt_end_commit(c);
	if (err)
		goto out;
	err = ubifs_orphan_end_commit(c);
	if (err)
		goto out;
	old_ltail_lnum = c->ltail_lnum;
	err = ubifs_log_end_commit(c, new_ltail_lnum);
	if (err)
		goto out;
	err = dbg_check_old_index(c, &zroot);
	if (err)
		goto out;

	mutex_lock(&c->mst_mutex);
	c->mst_node->cmt_no      = cpu_to_le64(c->cmt_no);
	c->mst_node->log_lnum    = cpu_to_le32(new_ltail_lnum);
	c->mst_node->root_lnum   = cpu_to_le32(zroot.lnum);
	c->mst_node->root_offs   = cpu_to_le32(zroot.offs);
	c->mst_node->root_len    = cpu_to_le32(zroot.len);
	c->mst_node->ihead_lnum  = cpu_to_le32(c->ihead_lnum);
	c->mst_node->ihead_offs  = cpu_to_le32(c->ihead_offs);
	c->mst_node->index_size  = cpu_to_le64(c->old_idx_sz);
	c->mst_node->lpt_lnum    = cpu_to_le32(c->lpt_lnum);
	c->mst_node->lpt_offs    = cpu_to_le32(c->lpt_offs);
	c->mst_node->nhead_lnum  = cpu_to_le32(c->nhead_lnum);
	c->mst_node->nhead_offs  = cpu_to_le32(c->nhead_offs);
	c->mst_node->ltab_lnum   = cpu_to_le32(c->ltab_lnum);
	c->mst_node->ltab_offs   = cpu_to_le32(c->ltab_offs);
	c->mst_node->lsave_lnum  = cpu_to_le32(c->lsave_lnum);
	c->mst_node->lsave_offs  = cpu_to_le32(c->lsave_offs);
	c->mst_node->lscan_lnum  = cpu_to_le32(c->lscan_lnum);
	c->mst_node->empty_lebs  = cpu_to_le32(lst.empty_lebs);
	c->mst_node->idx_lebs    = cpu_to_le32(lst.idx_lebs);
	c->mst_node->total_free  = cpu_to_le64(lst.total_free);
	c->mst_node->total_dirty = cpu_to_le64(lst.total_dirty);
	c->mst_node->total_used  = cpu_to_le64(lst.total_used);
	c->mst_node->total_dead  = cpu_to_le64(lst.total_dead);
	c->mst_node->total_dark  = cpu_to_le64(lst.total_dark);
	if (c->no_orphs)
		c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
	else
		c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_NO_ORPHS);
	err = ubifs_write_master(c);
	mutex_unlock(&c->mst_mutex);
	if (err)
		goto out;

	err = ubifs_log_post_commit(c, old_ltail_lnum);
	if (err)
		goto out;
	err = ubifs_gc_end_commit(c);
	if (err)
		goto out;
	err = ubifs_lpt_post_commit(c);
	if (err)
		goto out;

out_cancel:
	spin_lock(&c->cs_lock);
	c->cmt_state = COMMIT_RESTING;
	wake_up(&c->cmt_wq);
	dbg_cmt("commit end");
	spin_unlock(&c->cs_lock);
	return 0;

out_up:
	up_write(&c->commit_sem);
out:
	ubifs_err("commit failed, error %d", err);
	spin_lock(&c->cs_lock);
	c->cmt_state = COMMIT_BROKEN;
	wake_up(&c->cmt_wq);
	spin_unlock(&c->cs_lock);
	ubifs_ro_mode(c, err);
	return err;
}

/**
 * run_bg_commit - run background commit if it is needed.
 * @c: UBIFS file-system description object
 *
 * This function runs background commit if it is needed. Returns zero in case
 * of success and a negative error code in case of failure.
 */
static int run_bg_commit(struct ubifs_info *c)
{
	spin_lock(&c->cs_lock);
	/*
	 * Run background commit only if background commit was requested or if
	 * commit is required.
	 */
	if (c->cmt_state != COMMIT_BACKGROUND &&
	    c->cmt_state != COMMIT_REQUIRED)
		goto out;
	spin_unlock(&c->cs_lock);

	down_write(&c->commit_sem);
	spin_lock(&c->cs_lock);
	if (c->cmt_state == COMMIT_REQUIRED)
		c->cmt_state = COMMIT_RUNNING_REQUIRED;
	else if (c->cmt_state == COMMIT_BACKGROUND)
		c->cmt_state = COMMIT_RUNNING_BACKGROUND;
	else
		goto out_cmt_unlock;
	spin_unlock(&c->cs_lock);

	return do_commit(c);

out_cmt_unlock:
	up_write(&c->commit_sem);
out:
	spin_unlock(&c->cs_lock);
	return 0;
}

/**
 * ubifs_bg_thread - UBIFS background thread function.
 * @info: points to the file-system description object
 *
 * This function implements various file-system background activities:
 * o when a write-buffer timer expires it synchronizes the appropriate
 *   write-buffer;
 * o when the journal is about to be full, it starts in-advance commit.
 *
 * Note, other stuff like background garbage collection may be added here in
 * future.
 */
int ubifs_bg_thread(void *info)
{
	int err;
	struct ubifs_info *c = info;

	dbg_msg("background thread \"%s\" started, PID %d",
		c->bgt_name, current->pid);
	set_freezable();

	while (1) {
		if (kthread_should_stop())
			break;

		if (try_to_freeze())
			continue;

		set_current_state(TASK_INTERRUPTIBLE);
		/* Check if there is something to do */
		if (!c->need_bgt) {
			/*
			 * Nothing prevents us from going sleep now and
			 * be never woken up and block the task which
			 * could wait in 'kthread_stop()' forever.
			 */
			if (kthread_should_stop())
				break;
			schedule();
			continue;
		} else
			__set_current_state(TASK_RUNNING);

		c->need_bgt = 0;
		err = ubifs_bg_wbufs_sync(c);
		if (err)
			ubifs_ro_mode(c, err);

		run_bg_commit(c);
		cond_resched();
	}

	dbg_msg("background thread \"%s\" stops", c->bgt_name);
	return 0;
}

/**
 * ubifs_commit_required - set commit state to "required".
 * @c: UBIFS file-system description object
 *
 * This function is called if a commit is required but cannot be done from the
 * calling function, so it is just flagged instead.
 */
void ubifs_commit_required(struct ubifs_info *c)
{
	spin_lock(&c->cs_lock);
	switch (c->cmt_state) {
	case COMMIT_RESTING:
	case COMMIT_BACKGROUND:
		dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state),
			dbg_cstate(COMMIT_REQUIRED));
		c->cmt_state = COMMIT_REQUIRED;
		break;
	case COMMIT_RUNNING_BACKGROUND:
		dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state),
			dbg_cstate(COMMIT_RUNNING_REQUIRED));
		c->cmt_state = COMMIT_RUNNING_REQUIRED;
		break;
	case COMMIT_REQUIRED:
	case COMMIT_RUNNING_REQUIRED:
	case COMMIT_BROKEN:
		break;
	}
	spin_unlock(&c->cs_lock);
}

/**
 * ubifs_request_bg_commit - notify the background thread to do a commit.
 * @c: UBIFS file-system description object
 *
 * This function is called if the journal is full enough to make a commit
 * worthwhile, so background thread is kicked to start it.
 */
void ubifs_request_bg_commit(struct ubifs_info *c)
{
	spin_lock(&c->cs_lock);
	if (c->cmt_state == COMMIT_RESTING) {
		dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state),
			dbg_cstate(COMMIT_BACKGROUND));
		c->cmt_state = COMMIT_BACKGROUND;
		spin_unlock(&c->cs_lock);
		ubifs_wake_up_bgt(c);
	} else
		spin_unlock(&c->cs_lock);
}

/**
 * wait_for_commit - wait for commit.
 * @c: UBIFS file-system description object
 *
 * This function sleeps until the commit operation is no longer running.
 */
static int wait_for_commit(struct ubifs_info *c)
{
	dbg_cmt("pid %d goes sleep", current->pid);

	/*
	 * The following sleeps if the condition is false, and will be woken
	 * when the commit ends. It is possible, although very unlikely, that we
	 * will wake up and see the subsequent commit running, rather than the
	 * one we were waiting for, and go back to sleep.  However, we will be
	 * woken again, so there is no danger of sleeping forever.
	 */
	wait_event(c->cmt_wq, c->cmt_state != COMMIT_RUNNING_BACKGROUND &&
			      c->cmt_state != COMMIT_RUNNING_REQUIRED);
	dbg_cmt("commit finished, pid %d woke up", current->pid);
	return 0;
}

/**
 * ubifs_run_commit - run or wait for commit.
 * @c: UBIFS file-system description object
 *
 * This function runs commit and returns zero in case of success and a negative
 * error code in case of failure.
 */
int ubifs_run_commit(struct ubifs_info *c)
{
	int err = 0;

	spin_lock(&c->cs_lock);
	if (c->cmt_state == COMMIT_BROKEN) {
		err = -EINVAL;
		goto out;
	}

	if (c->cmt_state == COMMIT_RUNNING_BACKGROUND)
		/*
		 * We set the commit state to 'running required' to indicate
		 * that we want it to complete as quickly as possible.
		 */
		c->cmt_state = COMMIT_RUNNING_REQUIRED;

	if (c->cmt_state == COMMIT_RUNNING_REQUIRED) {
		spin_unlock(&c->cs_lock);
		return wait_for_commit(c);
	}
	spin_unlock(&c->cs_lock);

	/* Ok, the commit is indeed needed */

	down_write(&c->commit_sem);
	spin_lock(&c->cs_lock);
	/*
	 * Since we unlocked 'c->cs_lock', the state may have changed, so
	 * re-check it.
	 */
	if (c->cmt_state == COMMIT_BROKEN) {
		err = -EINVAL;
		goto out_cmt_unlock;
	}

	if (c->cmt_state == COMMIT_RUNNING_BACKGROUND)
		c->cmt_state = COMMIT_RUNNING_REQUIRED;

	if (c->cmt_state == COMMIT_RUNNING_REQUIRED) {
		up_write(&c->commit_sem);
		spin_unlock(&c->cs_lock);
		return wait_for_commit(c);
	}
	c->cmt_state = COMMIT_RUNNING_REQUIRED;
	spin_unlock(&c->cs_lock);

	err = do_commit(c);
	return err;

out_cmt_unlock:
	up_write(&c->commit_sem);
out:
	spin_unlock(&c->cs_lock);
	return err;
}

/**
 * ubifs_gc_should_commit - determine if it is time for GC to run commit.
 * @c: UBIFS file-system description object
 *
 * This function is called by garbage collection to determine if commit should
 * be run. If commit state is @COMMIT_BACKGROUND, which means that the journal
 * is full enough to start commit, this function returns true. It is not
 * absolutely necessary to commit yet, but it feels like this should be better
 * then to keep doing GC. This function returns %1 if GC has to initiate commit
 * and %0 if not.
 */
int ubifs_gc_should_commit(struct ubifs_info *c)
{
	int ret = 0;

	spin_lock(&c->cs_lock);
	if (c->cmt_state == COMMIT_BACKGROUND) {
		dbg_cmt("commit required now");
		c->cmt_state = COMMIT_REQUIRED;
	} else
		dbg_cmt("commit not requested");
	if (c->cmt_state == COMMIT_REQUIRED)
		ret = 1;
	spin_unlock(&c->cs_lock);
	return ret;
}

#ifdef CONFIG_UBIFS_FS_DEBUG

/**
 * struct idx_node - hold index nodes during index tree traversal.
 * @list: list
 * @iip: index in parent (slot number of this indexing node in the parent
 *       indexing node)
 * @upper_key: all keys in this indexing node have to be less or equivalent to
 *             this key
 * @idx: index node (8-byte aligned because all node structures must be 8-byte
 *       aligned)
 */
struct idx_node {
	struct list_head list;
	int iip;
	union ubifs_key upper_key;
	struct ubifs_idx_node idx __attribute__((aligned(8)));
};

/**
 * dbg_old_index_check_init - get information for the next old index check.
 * @c: UBIFS file-system description object
 * @zroot: root of the index
 *
 * This function records information about the index that will be needed for the
 * next old index check i.e. 'dbg_check_old_index()'.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int dbg_old_index_check_init(struct ubifs_info *c, struct ubifs_zbranch *zroot)
{
	struct ubifs_idx_node *idx;
	int lnum, offs, len, err = 0;
	struct ubifs_debug_info *d = c->dbg;

	d->old_zroot = *zroot;
	lnum = d->old_zroot.lnum;
	offs = d->old_zroot.offs;
	len = d->old_zroot.len;

	idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
	if (!idx)
		return -ENOMEM;

	err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
	if (err)
		goto out;

	d->old_zroot_level = le16_to_cpu(idx->level);
	d->old_zroot_sqnum = le64_to_cpu(idx->ch.sqnum);
out:
	kfree(idx);
	return err;
}

/**
 * dbg_check_old_index - check the old copy of the index.
 * @c: UBIFS file-system description object
 * @zroot: root of the new index
 *
 * In order to be able to recover from an unclean unmount, a complete copy of
 * the index must exist on flash. This is the "old" index. The commit process
 * must write the "new" index to flash without overwriting or destroying any
 * part of the old index. This function is run at commit end in order to check
 * that the old index does indeed exist completely intact.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int dbg_check_old_index(struct ubifs_info *c, struct ubifs_zbranch *zroot)
{
	int lnum, offs, len, err = 0, uninitialized_var(last_level), child_cnt;
	int first = 1, iip;
	struct ubifs_debug_info *d = c->dbg;
	union ubifs_key uninitialized_var(lower_key), upper_key, l_key, u_key;
	unsigned long long uninitialized_var(last_sqnum);
	struct ubifs_idx_node *idx;
	struct list_head list;
	struct idx_node *i;
	size_t sz;

	if (!(ubifs_chk_flags & UBIFS_CHK_OLD_IDX))
		goto out;

	INIT_LIST_HEAD(&list);

	sz = sizeof(struct idx_node) + ubifs_idx_node_sz(c, c->fanout) -
	     UBIFS_IDX_NODE_SZ;

	/* Start at the old zroot */
	lnum = d->old_zroot.lnum;
	offs = d->old_zroot.offs;
	len = d->old_zroot.len;
	iip = 0;

	/*
	 * Traverse the index tree preorder depth-first i.e. do a node and then
	 * its subtrees from left to right.
	 */
	while (1) {
		struct ubifs_branch *br;

		/* Get the next index node */
		i = kmalloc(sz, GFP_NOFS);
		if (!i) {
			err = -ENOMEM;
			goto out_free;
		}
		i->iip = iip;
		/* Keep the index nodes on our path in a linked list */
		list_add_tail(&i->list, &list);
		/* Read the index node */
		idx = &i->idx;
		err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
		if (err)
			goto out_free;
		/* Validate index node */
		child_cnt = le16_to_cpu(idx->child_cnt);
		if (child_cnt < 1 || child_cnt > c->fanout) {
			err = 1;
			goto out_dump;
		}
		if (first) {
			first = 0;
			/* Check root level and sqnum */
			if (le16_to_cpu(idx->level) != d->old_zroot_level) {
				err = 2;
				goto out_dump;
			}
			if (le64_to_cpu(idx->ch.sqnum) != d->old_zroot_sqnum) {
				err = 3;
				goto out_dump;
			}
			/* Set last values as though root had a parent */
			last_level = le16_to_cpu(idx->level) + 1;
			last_sqnum = le64_to_cpu(idx->ch.sqnum) + 1;
			key_read(c, ubifs_idx_key(c, idx), &lower_key);
			highest_ino_key(c, &upper_key, INUM_WATERMARK);
		}
		key_copy(c, &upper_key, &i->upper_key);
		if (le16_to_cpu(idx->level) != last_level - 1) {
			err = 3;
			goto out_dump;
		}
		/*
		 * The index is always written bottom up hence a child's sqnum
		 * is always less than the parents.
		 */
		if (le64_to_cpu(idx->ch.sqnum) >= last_sqnum) {
			err = 4;
			goto out_dump;
		}
		/* Check key range */
		key_read(c, ubifs_idx_key(c, idx), &l_key);
		br = ubifs_idx_branch(c, idx, child_cnt - 1);
		key_read(c, &br->key, &u_key);
		if (keys_cmp(c, &lower_key, &l_key) > 0) {
			err = 5;
			goto out_dump;
		}
		if (keys_cmp(c, &upper_key, &u_key) < 0) {
			err = 6;
			goto out_dump;
		}
		if (keys_cmp(c, &upper_key, &u_key) == 0)
			if (!is_hash_key(c, &u_key)) {
				err = 7;
				goto out_dump;
			}
		/* Go to next index node */
		if (le16_to_cpu(idx->level) == 0) {
			/* At the bottom, so go up until can go right */
			while (1) {
				/* Drop the bottom of the list */
				list_del(&i->list);
				kfree(i);
				/* No more list means we are done */
				if (list_empty(&list))
					goto out;
				/* Look at the new bottom */
				i = list_entry(list.prev, struct idx_node,
					       list);
				idx = &i->idx;
				/* Can we go right */
				if (iip + 1 < le16_to_cpu(idx->child_cnt)) {
					iip = iip + 1;
					break;
				} else
					/* Nope, so go up again */
					iip = i->iip;
			}
		} else
			/* Go down left */
			iip = 0;
		/*
		 * We have the parent in 'idx' and now we set up for reading the
		 * child pointed to by slot 'iip'.
		 */
		last_level = le16_to_cpu(idx->level);
		last_sqnum = le64_to_cpu(idx->ch.sqnum);
		br = ubifs_idx_branch(c, idx, iip);
		lnum = le32_to_cpu(br->lnum);
		offs = le32_to_cpu(br->offs);
		len = le32_to_cpu(br->len);
		key_read(c, &br->key, &lower_key);
		if (iip + 1 < le16_to_cpu(idx->child_cnt)) {
			br = ubifs_idx_branch(c, idx, iip + 1);
			key_read(c, &br->key, &upper_key);
		} else
			key_copy(c, &i->upper_key, &upper_key);
	}
out:
	err = dbg_old_index_check_init(c, zroot);
	if (err)
		goto out_free;

	return 0;

out_dump:
	dbg_err("dumping index node (iip=%d)", i->iip);
	dbg_dump_node(c, idx);
	list_del(&i->list);
	kfree(i);
	if (!list_empty(&list)) {
		i = list_entry(list.prev, struct idx_node, list);
		dbg_err("dumping parent index node");
		dbg_dump_node(c, &i->idx);
	}
out_free:
	while (!list_empty(&list)) {
		i = list_entry(list.next, struct idx_node, list);
		list_del(&i->list);
		kfree(i);
	}
	ubifs_err("failed, error %d", err);
	if (err > 0)
		err = -EINVAL;
	return err;
}

#endif /* CONFIG_UBIFS_FS_DEBUG */