summaryrefslogtreecommitdiff
path: root/fs/ubifs/log.c
blob: 0355fe2b048f73db36001255a5797263f4272244 (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
/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * SPDX-License-Identifier:	GPL-2.0+
 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 */

/*
 * This file is a part of UBIFS journal implementation and contains various
 * functions which manipulate the log. The log is a fixed area on the flash
 * which does not contain any data but refers to buds. The log is a part of the
 * journal.
 */

#ifdef __UBOOT__
#include <linux/err.h>
#endif
#include "ubifs.h"

static int dbg_check_bud_bytes(struct ubifs_info *c);

/**
 * ubifs_search_bud - search bud LEB.
 * @c: UBIFS file-system description object
 * @lnum: logical eraseblock number to search
 *
 * This function searches bud LEB @lnum. Returns bud description object in case
 * of success and %NULL if there is no bud with this LEB number.
 */
struct ubifs_bud *ubifs_search_bud(struct ubifs_info *c, int lnum)
{
	struct rb_node *p;
	struct ubifs_bud *bud;

	spin_lock(&c->buds_lock);
	p = c->buds.rb_node;
	while (p) {
		bud = rb_entry(p, struct ubifs_bud, rb);
		if (lnum < bud->lnum)
			p = p->rb_left;
		else if (lnum > bud->lnum)
			p = p->rb_right;
		else {
			spin_unlock(&c->buds_lock);
			return bud;
		}
	}
	spin_unlock(&c->buds_lock);
	return NULL;
}

/**
 * ubifs_get_wbuf - get the wbuf associated with a LEB, if there is one.
 * @c: UBIFS file-system description object
 * @lnum: logical eraseblock number to search
 *
 * This functions returns the wbuf for @lnum or %NULL if there is not one.
 */
struct ubifs_wbuf *ubifs_get_wbuf(struct ubifs_info *c, int lnum)
{
	struct rb_node *p;
	struct ubifs_bud *bud;
	int jhead;

	if (!c->jheads)
		return NULL;

	spin_lock(&c->buds_lock);
	p = c->buds.rb_node;
	while (p) {
		bud = rb_entry(p, struct ubifs_bud, rb);
		if (lnum < bud->lnum)
			p = p->rb_left;
		else if (lnum > bud->lnum)
			p = p->rb_right;
		else {
			jhead = bud->jhead;
			spin_unlock(&c->buds_lock);
			return &c->jheads[jhead].wbuf;
		}
	}
	spin_unlock(&c->buds_lock);
	return NULL;
}

/**
 * empty_log_bytes - calculate amount of empty space in the log.
 * @c: UBIFS file-system description object
 */
static inline long long empty_log_bytes(const struct ubifs_info *c)
{
	long long h, t;

	h = (long long)c->lhead_lnum * c->leb_size + c->lhead_offs;
	t = (long long)c->ltail_lnum * c->leb_size;

	if (h >= t)
		return c->log_bytes - h + t;
	else
		return t - h;
}

/**
 * ubifs_add_bud - add bud LEB to the tree of buds and its journal head list.
 * @c: UBIFS file-system description object
 * @bud: the bud to add
 */
void ubifs_add_bud(struct ubifs_info *c, struct ubifs_bud *bud)
{
	struct rb_node **p, *parent = NULL;
	struct ubifs_bud *b;
	struct ubifs_jhead *jhead;

	spin_lock(&c->buds_lock);
	p = &c->buds.rb_node;
	while (*p) {
		parent = *p;
		b = rb_entry(parent, struct ubifs_bud, rb);
		ubifs_assert(bud->lnum != b->lnum);
		if (bud->lnum < b->lnum)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
	}

	rb_link_node(&bud->rb, parent, p);
	rb_insert_color(&bud->rb, &c->buds);
	if (c->jheads) {
		jhead = &c->jheads[bud->jhead];
		list_add_tail(&bud->list, &jhead->buds_list);
	} else
		ubifs_assert(c->replaying && c->ro_mount);

	/*
	 * Note, although this is a new bud, we anyway account this space now,
	 * before any data has been written to it, because this is about to
	 * guarantee fixed mount time, and this bud will anyway be read and
	 * scanned.
	 */
	c->bud_bytes += c->leb_size - bud->start;

	dbg_log("LEB %d:%d, jhead %s, bud_bytes %lld", bud->lnum,
		bud->start, dbg_jhead(bud->jhead), c->bud_bytes);
	spin_unlock(&c->buds_lock);
}

/**
 * ubifs_add_bud_to_log - add a new bud to the log.
 * @c: UBIFS file-system description object
 * @jhead: journal head the bud belongs to
 * @lnum: LEB number of the bud
 * @offs: starting offset of the bud
 *
 * This function writes reference node for the new bud LEB @lnum it to the log,
 * and adds it to the buds tress. It also makes sure that log size does not
 * exceed the 'c->max_bud_bytes' limit. Returns zero in case of success,
 * %-EAGAIN if commit is required, and a negative error codes in case of
 * failure.
 */
int ubifs_add_bud_to_log(struct ubifs_info *c, int jhead, int lnum, int offs)
{
	int err;
	struct ubifs_bud *bud;
	struct ubifs_ref_node *ref;

	bud = kmalloc(sizeof(struct ubifs_bud), GFP_NOFS);
	if (!bud)
		return -ENOMEM;
	ref = kzalloc(c->ref_node_alsz, GFP_NOFS);
	if (!ref) {
		kfree(bud);
		return -ENOMEM;
	}

	mutex_lock(&c->log_mutex);
	ubifs_assert(!c->ro_media && !c->ro_mount);
	if (c->ro_error) {
		err = -EROFS;
		goto out_unlock;
	}

	/* Make sure we have enough space in the log */
	if (empty_log_bytes(c) - c->ref_node_alsz < c->min_log_bytes) {
		dbg_log("not enough log space - %lld, required %d",
			empty_log_bytes(c), c->min_log_bytes);
		ubifs_commit_required(c);
		err = -EAGAIN;
		goto out_unlock;
	}

	/*
	 * Make sure the amount of space in buds will not exceed the
	 * 'c->max_bud_bytes' limit, because we want to guarantee mount time
	 * limits.
	 *
	 * It is not necessary to hold @c->buds_lock when reading @c->bud_bytes
	 * because we are holding @c->log_mutex. All @c->bud_bytes take place
	 * when both @c->log_mutex and @c->bud_bytes are locked.
	 */
	if (c->bud_bytes + c->leb_size - offs > c->max_bud_bytes) {
		dbg_log("bud bytes %lld (%lld max), require commit",
			c->bud_bytes, c->max_bud_bytes);
		ubifs_commit_required(c);
		err = -EAGAIN;
		goto out_unlock;
	}

	/*
	 * If the journal is full enough - start background commit. Note, it is
	 * OK to read 'c->cmt_state' without spinlock because integer reads
	 * are atomic in the kernel.
	 */
	if (c->bud_bytes >= c->bg_bud_bytes &&
	    c->cmt_state == COMMIT_RESTING) {
		dbg_log("bud bytes %lld (%lld max), initiate BG commit",
			c->bud_bytes, c->max_bud_bytes);
		ubifs_request_bg_commit(c);
	}

	bud->lnum = lnum;
	bud->start = offs;
	bud->jhead = jhead;

	ref->ch.node_type = UBIFS_REF_NODE;
	ref->lnum = cpu_to_le32(bud->lnum);
	ref->offs = cpu_to_le32(bud->start);
	ref->jhead = cpu_to_le32(jhead);

	if (c->lhead_offs > c->leb_size - c->ref_node_alsz) {
		c->lhead_lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
		c->lhead_offs = 0;
	}

	if (c->lhead_offs == 0) {
		/* Must ensure next log LEB has been unmapped */
		err = ubifs_leb_unmap(c, c->lhead_lnum);
		if (err)
			goto out_unlock;
	}

	if (bud->start == 0) {
		/*
		 * Before writing the LEB reference which refers an empty LEB
		 * to the log, we have to make sure it is mapped, because
		 * otherwise we'd risk to refer an LEB with garbage in case of
		 * an unclean reboot, because the target LEB might have been
		 * unmapped, but not yet physically erased.
		 */
		err = ubifs_leb_map(c, bud->lnum);
		if (err)
			goto out_unlock;
	}

	dbg_log("write ref LEB %d:%d",
		c->lhead_lnum, c->lhead_offs);
	err = ubifs_write_node(c, ref, UBIFS_REF_NODE_SZ, c->lhead_lnum,
			       c->lhead_offs);
	if (err)
		goto out_unlock;

	c->lhead_offs += c->ref_node_alsz;

	ubifs_add_bud(c, bud);

	mutex_unlock(&c->log_mutex);
	kfree(ref);
	return 0;

out_unlock:
	mutex_unlock(&c->log_mutex);
	kfree(ref);
	kfree(bud);
	return err;
}

/**
 * remove_buds - remove used buds.
 * @c: UBIFS file-system description object
 *
 * This function removes use buds from the buds tree. It does not remove the
 * buds which are pointed to by journal heads.
 */
static void remove_buds(struct ubifs_info *c)
{
	struct rb_node *p;

	ubifs_assert(list_empty(&c->old_buds));
	c->cmt_bud_bytes = 0;
	spin_lock(&c->buds_lock);
	p = rb_first(&c->buds);
	while (p) {
		struct rb_node *p1 = p;
		struct ubifs_bud *bud;
		struct ubifs_wbuf *wbuf;

		p = rb_next(p);
		bud = rb_entry(p1, struct ubifs_bud, rb);
		wbuf = &c->jheads[bud->jhead].wbuf;

		if (wbuf->lnum == bud->lnum) {
			/*
			 * Do not remove buds which are pointed to by journal
			 * heads (non-closed buds).
			 */
			c->cmt_bud_bytes += wbuf->offs - bud->start;
			dbg_log("preserve %d:%d, jhead %s, bud bytes %d, cmt_bud_bytes %lld",
				bud->lnum, bud->start, dbg_jhead(bud->jhead),
				wbuf->offs - bud->start, c->cmt_bud_bytes);
			bud->start = wbuf->offs;
		} else {
			c->cmt_bud_bytes += c->leb_size - bud->start;
			dbg_log("remove %d:%d, jhead %s, bud bytes %d, cmt_bud_bytes %lld",
				bud->lnum, bud->start, dbg_jhead(bud->jhead),
				c->leb_size - bud->start, c->cmt_bud_bytes);
			rb_erase(p1, &c->buds);
			/*
			 * If the commit does not finish, the recovery will need
			 * to replay the journal, in which case the old buds
			 * must be unchanged. Do not release them until post
			 * commit i.e. do not allow them to be garbage
			 * collected.
			 */
			list_move(&bud->list, &c->old_buds);
		}
	}
	spin_unlock(&c->buds_lock);
}

/**
 * ubifs_log_start_commit - start commit.
 * @c: UBIFS file-system description object
 * @ltail_lnum: return new log tail LEB number
 *
 * The commit operation starts with writing "commit start" node to the log and
 * reference nodes for all journal heads which will define new journal after
 * the commit has been finished. The commit start and reference nodes are
 * written in one go to the nearest empty log LEB (hence, when commit is
 * finished UBIFS may safely unmap all the previous log LEBs). This function
 * returns zero in case of success and a negative error code in case of
 * failure.
 */
int ubifs_log_start_commit(struct ubifs_info *c, int *ltail_lnum)
{
	void *buf;
	struct ubifs_cs_node *cs;
	struct ubifs_ref_node *ref;
	int err, i, max_len, len;

	err = dbg_check_bud_bytes(c);
	if (err)
		return err;

	max_len = UBIFS_CS_NODE_SZ + c->jhead_cnt * UBIFS_REF_NODE_SZ;
	max_len = ALIGN(max_len, c->min_io_size);
	buf = cs = kmalloc(max_len, GFP_NOFS);
	if (!buf)
		return -ENOMEM;

	cs->ch.node_type = UBIFS_CS_NODE;
	cs->cmt_no = cpu_to_le64(c->cmt_no);
	ubifs_prepare_node(c, cs, UBIFS_CS_NODE_SZ, 0);

	/*
	 * Note, we do not lock 'c->log_mutex' because this is the commit start
	 * phase and we are exclusively using the log. And we do not lock
	 * write-buffer because nobody can write to the file-system at this
	 * phase.
	 */

	len = UBIFS_CS_NODE_SZ;
	for (i = 0; i < c->jhead_cnt; i++) {
		int lnum = c->jheads[i].wbuf.lnum;
		int offs = c->jheads[i].wbuf.offs;

		if (lnum == -1 || offs == c->leb_size)
			continue;

		dbg_log("add ref to LEB %d:%d for jhead %s",
			lnum, offs, dbg_jhead(i));
		ref = buf + len;
		ref->ch.node_type = UBIFS_REF_NODE;
		ref->lnum = cpu_to_le32(lnum);
		ref->offs = cpu_to_le32(offs);
		ref->jhead = cpu_to_le32(i);

		ubifs_prepare_node(c, ref, UBIFS_REF_NODE_SZ, 0);
		len += UBIFS_REF_NODE_SZ;
	}

	ubifs_pad(c, buf + len, ALIGN(len, c->min_io_size) - len);

	/* Switch to the next log LEB */
	if (c->lhead_offs) {
		c->lhead_lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
		c->lhead_offs = 0;
	}

	if (c->lhead_offs == 0) {
		/* Must ensure next LEB has been unmapped */
		err = ubifs_leb_unmap(c, c->lhead_lnum);
		if (err)
			goto out;
	}

	len = ALIGN(len, c->min_io_size);
	dbg_log("writing commit start at LEB %d:0, len %d", c->lhead_lnum, len);
	err = ubifs_leb_write(c, c->lhead_lnum, cs, 0, len);
	if (err)
		goto out;

	*ltail_lnum = c->lhead_lnum;

	c->lhead_offs += len;
	if (c->lhead_offs == c->leb_size) {
		c->lhead_lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
		c->lhead_offs = 0;
	}

	remove_buds(c);

	/*
	 * We have started the commit and now users may use the rest of the log
	 * for new writes.
	 */
	c->min_log_bytes = 0;

out:
	kfree(buf);
	return err;
}

/**
 * ubifs_log_end_commit - end commit.
 * @c: UBIFS file-system description object
 * @ltail_lnum: new log tail LEB number
 *
 * This function is called on when the commit operation was finished. It
 * moves log tail to new position and unmaps LEBs which contain obsolete data.
 * Returns zero in case of success and a negative error code in case of
 * failure.
 */
int ubifs_log_end_commit(struct ubifs_info *c, int ltail_lnum)
{
	int err;

	/*
	 * At this phase we have to lock 'c->log_mutex' because UBIFS allows FS
	 * writes during commit. Its only short "commit" start phase when
	 * writers are blocked.
	 */
	mutex_lock(&c->log_mutex);

	dbg_log("old tail was LEB %d:0, new tail is LEB %d:0",
		c->ltail_lnum, ltail_lnum);

	c->ltail_lnum = ltail_lnum;
	/*
	 * The commit is finished and from now on it must be guaranteed that
	 * there is always enough space for the next commit.
	 */
	c->min_log_bytes = c->leb_size;

	spin_lock(&c->buds_lock);
	c->bud_bytes -= c->cmt_bud_bytes;
	spin_unlock(&c->buds_lock);

	err = dbg_check_bud_bytes(c);

	mutex_unlock(&c->log_mutex);
	return err;
}

/**
 * ubifs_log_post_commit - things to do after commit is completed.
 * @c: UBIFS file-system description object
 * @old_ltail_lnum: old log tail LEB number
 *
 * Release buds only after commit is completed, because they must be unchanged
 * if recovery is needed.
 *
 * Unmap log LEBs only after commit is completed, because they may be needed for
 * recovery.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_log_post_commit(struct ubifs_info *c, int old_ltail_lnum)
{
	int lnum, err = 0;

	while (!list_empty(&c->old_buds)) {
		struct ubifs_bud *bud;

		bud = list_entry(c->old_buds.next, struct ubifs_bud, list);
		err = ubifs_return_leb(c, bud->lnum);
		if (err)
			return err;
		list_del(&bud->list);
		kfree(bud);
	}
	mutex_lock(&c->log_mutex);
	for (lnum = old_ltail_lnum; lnum != c->ltail_lnum;
	     lnum = ubifs_next_log_lnum(c, lnum)) {
		dbg_log("unmap log LEB %d", lnum);
		err = ubifs_leb_unmap(c, lnum);
		if (err)
			goto out;
	}
out:
	mutex_unlock(&c->log_mutex);
	return err;
}

/**
 * struct done_ref - references that have been done.
 * @rb: rb-tree node
 * @lnum: LEB number
 */
struct done_ref {
	struct rb_node rb;
	int lnum;
};

/**
 * done_already - determine if a reference has been done already.
 * @done_tree: rb-tree to store references that have been done
 * @lnum: LEB number of reference
 *
 * This function returns %1 if the reference has been done, %0 if not, otherwise
 * a negative error code is returned.
 */
static int done_already(struct rb_root *done_tree, int lnum)
{
	struct rb_node **p = &done_tree->rb_node, *parent = NULL;
	struct done_ref *dr;

	while (*p) {
		parent = *p;
		dr = rb_entry(parent, struct done_ref, rb);
		if (lnum < dr->lnum)
			p = &(*p)->rb_left;
		else if (lnum > dr->lnum)
			p = &(*p)->rb_right;
		else
			return 1;
	}

	dr = kzalloc(sizeof(struct done_ref), GFP_NOFS);
	if (!dr)
		return -ENOMEM;

	dr->lnum = lnum;

	rb_link_node(&dr->rb, parent, p);
	rb_insert_color(&dr->rb, done_tree);

	return 0;
}

/**
 * destroy_done_tree - destroy the done tree.
 * @done_tree: done tree to destroy
 */
static void destroy_done_tree(struct rb_root *done_tree)
{
	struct done_ref *dr, *n;

	rbtree_postorder_for_each_entry_safe(dr, n, done_tree, rb)
		kfree(dr);
}

/**
 * add_node - add a node to the consolidated log.
 * @c: UBIFS file-system description object
 * @buf: buffer to which to add
 * @lnum: LEB number to which to write is passed and returned here
 * @offs: offset to where to write is passed and returned here
 * @node: node to add
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int add_node(struct ubifs_info *c, void *buf, int *lnum, int *offs,
		    void *node)
{
	struct ubifs_ch *ch = node;
	int len = le32_to_cpu(ch->len), remains = c->leb_size - *offs;

	if (len > remains) {
		int sz = ALIGN(*offs, c->min_io_size), err;

		ubifs_pad(c, buf + *offs, sz - *offs);
		err = ubifs_leb_change(c, *lnum, buf, sz);
		if (err)
			return err;
		*lnum = ubifs_next_log_lnum(c, *lnum);
		*offs = 0;
	}
	memcpy(buf + *offs, node, len);
	*offs += ALIGN(len, 8);
	return 0;
}

/**
 * ubifs_consolidate_log - consolidate the log.
 * @c: UBIFS file-system description object
 *
 * Repeated failed commits could cause the log to be full, but at least 1 LEB is
 * needed for commit. This function rewrites the reference nodes in the log
 * omitting duplicates, and failed CS nodes, and leaving no gaps.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_consolidate_log(struct ubifs_info *c)
{
	struct ubifs_scan_leb *sleb;
	struct ubifs_scan_node *snod;
	struct rb_root done_tree = RB_ROOT;
	int lnum, err, first = 1, write_lnum, offs = 0;
	void *buf;

	dbg_rcvry("log tail LEB %d, log head LEB %d", c->ltail_lnum,
		  c->lhead_lnum);
	buf = vmalloc(c->leb_size);
	if (!buf)
		return -ENOMEM;
	lnum = c->ltail_lnum;
	write_lnum = lnum;
	while (1) {
		sleb = ubifs_scan(c, lnum, 0, c->sbuf, 0);
		if (IS_ERR(sleb)) {
			err = PTR_ERR(sleb);
			goto out_free;
		}
		list_for_each_entry(snod, &sleb->nodes, list) {
			switch (snod->type) {
			case UBIFS_REF_NODE: {
				struct ubifs_ref_node *ref = snod->node;
				int ref_lnum = le32_to_cpu(ref->lnum);

				err = done_already(&done_tree, ref_lnum);
				if (err < 0)
					goto out_scan;
				if (err != 1) {
					err = add_node(c, buf, &write_lnum,
						       &offs, snod->node);
					if (err)
						goto out_scan;
				}
				break;
			}
			case UBIFS_CS_NODE:
				if (!first)
					break;
				err = add_node(c, buf, &write_lnum, &offs,
					       snod->node);
				if (err)
					goto out_scan;
				first = 0;
				break;
			}
		}
		ubifs_scan_destroy(sleb);
		if (lnum == c->lhead_lnum)
			break;
		lnum = ubifs_next_log_lnum(c, lnum);
	}
	if (offs) {
		int sz = ALIGN(offs, c->min_io_size);

		ubifs_pad(c, buf + offs, sz - offs);
		err = ubifs_leb_change(c, write_lnum, buf, sz);
		if (err)
			goto out_free;
		offs = ALIGN(offs, c->min_io_size);
	}
	destroy_done_tree(&done_tree);
	vfree(buf);
	if (write_lnum == c->lhead_lnum) {
		ubifs_err("log is too full");
		return -EINVAL;
	}
	/* Unmap remaining LEBs */
	lnum = write_lnum;
	do {
		lnum = ubifs_next_log_lnum(c, lnum);
		err = ubifs_leb_unmap(c, lnum);
		if (err)
			return err;
	} while (lnum != c->lhead_lnum);
	c->lhead_lnum = write_lnum;
	c->lhead_offs = offs;
	dbg_rcvry("new log head at %d:%d", c->lhead_lnum, c->lhead_offs);
	return 0;

out_scan:
	ubifs_scan_destroy(sleb);
out_free:
	destroy_done_tree(&done_tree);
	vfree(buf);
	return err;
}

/**
 * dbg_check_bud_bytes - make sure bud bytes calculation are all right.
 * @c: UBIFS file-system description object
 *
 * This function makes sure the amount of flash space used by closed buds
 * ('c->bud_bytes' is correct). Returns zero in case of success and %-EINVAL in
 * case of failure.
 */
static int dbg_check_bud_bytes(struct ubifs_info *c)
{
	int i, err = 0;
	struct ubifs_bud *bud;
	long long bud_bytes = 0;

	if (!dbg_is_chk_gen(c))
		return 0;

	spin_lock(&c->buds_lock);
	for (i = 0; i < c->jhead_cnt; i++)
		list_for_each_entry(bud, &c->jheads[i].buds_list, list)
			bud_bytes += c->leb_size - bud->start;

	if (c->bud_bytes != bud_bytes) {
		ubifs_err("bad bud_bytes %lld, calculated %lld",
			  c->bud_bytes, bud_bytes);
		err = -EINVAL;
	}
	spin_unlock(&c->buds_lock);

	return err;
}