aboutsummaryrefslogtreecommitdiffstats
path: root/fs/ubifs/recovery.c
blob: e2714f8f05ffea99ded1427626de8e6f30739932 (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
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
/*
 * 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 needed to recover from unclean un-mounts.
 * When UBIFS is mounted, it checks a flag on the master node to determine if
 * an un-mount was completed successfully. If not, the process of mounting
 * incorporates additional checking and fixing of on-flash data structures.
 * UBIFS always cleans away all remnants of an unclean un-mount, so that
 * errors do not accumulate. However UBIFS defers recovery if it is mounted
 * read-only, and the flash is not modified in that case.
 *
 * The general UBIFS approach to the recovery is that it recovers from
 * corruptions which could be caused by power cuts, but it refuses to recover
 * from corruption caused by other reasons. And UBIFS tries to distinguish
 * between these 2 reasons of corruptions and silently recover in the former
 * case and loudly complain in the latter case.
 *
 * UBIFS writes only to erased LEBs, so it writes only to the flash space
 * containing only 0xFFs. UBIFS also always writes strictly from the beginning
 * of the LEB to the end. And UBIFS assumes that the underlying flash media
 * writes in @c->min_io_unit bytes at a time.
 *
 * Hence, if UBIFS finds a corrupted node at offset X, it expects only the min.
 * I/O unit corresponding to offset X to contain corrupted data, all the
 * following min. I/O units have to contain empty space (all 0xFFs). If this is
 * not true, the corruption cannot be the result of a power cut, and UBIFS
 * refuses to mount.
 */

#include <linux/crc32.h>
#include <linux/slab.h>
#include "ubifs.h"

/**
 * is_empty - determine whether a buffer is empty (contains all 0xff).
 * @buf: buffer to clean
 * @len: length of buffer
 *
 * This function returns %1 if the buffer is empty (contains all 0xff) otherwise
 * %0 is returned.
 */
static int is_empty(void *buf, int len)
{
	uint8_t *p = buf;
	int i;

	for (i = 0; i < len; i++)
		if (*p++ != 0xff)
			return 0;
	return 1;
}

/**
 * first_non_ff - find offset of the first non-0xff byte.
 * @buf: buffer to search in
 * @len: length of buffer
 *
 * This function returns offset of the first non-0xff byte in @buf or %-1 if
 * the buffer contains only 0xff bytes.
 */
static int first_non_ff(void *buf, int len)
{
	uint8_t *p = buf;
	int i;

	for (i = 0; i < len; i++)
		if (*p++ != 0xff)
			return i;
	return -1;
}

/**
 * get_master_node - get the last valid master node allowing for corruption.
 * @c: UBIFS file-system description object
 * @lnum: LEB number
 * @pbuf: buffer containing the LEB read, is returned here
 * @mst: master node, if found, is returned here
 * @cor: corruption, if found, is returned here
 *
 * This function allocates a buffer, reads the LEB into it, and finds and
 * returns the last valid master node allowing for one area of corruption.
 * The corrupt area, if there is one, must be consistent with the assumption
 * that it is the result of an unclean unmount while the master node was being
 * written. Under those circumstances, it is valid to use the previously written
 * master node.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int get_master_node(const struct ubifs_info *c, int lnum, void **pbuf,
			   struct ubifs_mst_node **mst, void **cor)
{
	const int sz = c->mst_node_alsz;
	int err, offs, len;
	void *sbuf, *buf;

	sbuf = vmalloc(c->leb_size);
	if (!sbuf)
		return -ENOMEM;

	err = ubi_read(c->ubi, lnum, sbuf, 0, c->leb_size);
	if (err && err != -EBADMSG)
		goto out_free;

	/* Find the first position that is definitely not a node */
	offs = 0;
	buf = sbuf;
	len = c->leb_size;
	while (offs + UBIFS_MST_NODE_SZ <= c->leb_size) {
		struct ubifs_ch *ch = buf;

		if (le32_to_cpu(ch->magic) != UBIFS_NODE_MAGIC)
			break;
		offs += sz;
		buf  += sz;
		len  -= sz;
	}
	/* See if there was a valid master node before that */
	if (offs) {
		int ret;

		offs -= sz;
		buf  -= sz;
		len  += sz;
		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
		if (ret != SCANNED_A_NODE && offs) {
			/* Could have been corruption so check one place back */
			offs -= sz;
			buf  -= sz;
			len  += sz;
			ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
			if (ret != SCANNED_A_NODE)
				/*
				 * We accept only one area of corruption because
				 * we are assuming that it was caused while
				 * trying to write a master node.
				 */
				goto out_err;
		}
		if (ret == SCANNED_A_NODE) {
			struct ubifs_ch *ch = buf;

			if (ch->node_type != UBIFS_MST_NODE)
				goto out_err;
			dbg_rcvry("found a master node at %d:%d", lnum, offs);
			*mst = buf;
			offs += sz;
			buf  += sz;
			len  -= sz;
		}
	}
	/* Check for corruption */
	if (offs < c->leb_size) {
		if (!is_empty(buf, min_t(int, len, sz))) {
			*cor = buf;
			dbg_rcvry("found corruption at %d:%d", lnum, offs);
		}
		offs += sz;
		buf  += sz;
		len  -= sz;
	}
	/* Check remaining empty space */
	if (offs < c->leb_size)
		if (!is_empty(buf, len))
			goto out_err;
	*pbuf = sbuf;
	return 0;

out_err:
	err = -EINVAL;
out_free:
	vfree(sbuf);
	*mst = NULL;
	*cor = NULL;
	return err;
}

/**
 * write_rcvrd_mst_node - write recovered master node.
 * @c: UBIFS file-system description object
 * @mst: master node
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int write_rcvrd_mst_node(struct ubifs_info *c,
				struct ubifs_mst_node *mst)
{
	int err = 0, lnum = UBIFS_MST_LNUM, sz = c->mst_node_alsz;
	__le32 save_flags;

	dbg_rcvry("recovery");

	save_flags = mst->flags;
	mst->flags |= cpu_to_le32(UBIFS_MST_RCVRY);

	ubifs_prepare_node(c, mst, UBIFS_MST_NODE_SZ, 1);
	err = ubi_leb_change(c->ubi, lnum, mst, sz, UBI_SHORTTERM);
	if (err)
		goto out;
	err = ubi_leb_change(c->ubi, lnum + 1, mst, sz, UBI_SHORTTERM);
	if (err)
		goto out;
out:
	mst->flags = save_flags;
	return err;
}

/**
 * ubifs_recover_master_node - recover the master node.
 * @c: UBIFS file-system description object
 *
 * This function recovers the master node from corruption that may occur due to
 * an unclean unmount.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_recover_master_node(struct ubifs_info *c)
{
	void *buf1 = NULL, *buf2 = NULL, *cor1 = NULL, *cor2 = NULL;
	struct ubifs_mst_node *mst1 = NULL, *mst2 = NULL, *mst;
	const int sz = c->mst_node_alsz;
	int err, offs1, offs2;

	dbg_rcvry("recovery");

	err = get_master_node(c, UBIFS_MST_LNUM, &buf1, &mst1, &cor1);
	if (err)
		goto out_free;

	err = get_master_node(c, UBIFS_MST_LNUM + 1, &buf2, &mst2, &cor2);
	if (err)
		goto out_free;

	if (mst1) {
		offs1 = (void *)mst1 - buf1;
		if ((le32_to_cpu(mst1->flags) & UBIFS_MST_RCVRY) &&
		    (offs1 == 0 && !cor1)) {
			/*
			 * mst1 was written by recovery at offset 0 with no
			 * corruption.
			 */
			dbg_rcvry("recovery recovery");
			mst = mst1;
		} else if (mst2) {
			offs2 = (void *)mst2 - buf2;
			if (offs1 == offs2) {
				/* Same offset, so must be the same */
				if (memcmp((void *)mst1 + UBIFS_CH_SZ,
					   (void *)mst2 + UBIFS_CH_SZ,
					   UBIFS_MST_NODE_SZ - UBIFS_CH_SZ))
					goto out_err;
				mst = mst1;
			} else if (offs2 + sz == offs1) {
				/* 1st LEB was written, 2nd was not */
				if (cor1)
					goto out_err;
				mst = mst1;
			} else if (offs1 == 0 && offs2 + sz >= c->leb_size) {
				/* 1st LEB was unmapped and written, 2nd not */
				if (cor1)
					goto out_err;
				mst = mst1;
			} else
				goto out_err;
		} else {
			/*
			 * 2nd LEB was unmapped and about to be written, so
			 * there must be only one master node in the first LEB
			 * and no corruption.
			 */
			if (offs1 != 0 || cor1)
				goto out_err;
			mst = mst1;
		}
	} else {
		if (!mst2)
			goto out_err;
		/*
		 * 1st LEB was unmapped and about to be written, so there must
		 * be no room left in 2nd LEB.
		 */
		offs2 = (void *)mst2 - buf2;
		if (offs2 + sz + sz <= c->leb_size)
			goto out_err;
		mst = mst2;
	}

	ubifs_msg("recovered master node from LEB %d",
		  (mst == mst1 ? UBIFS_MST_LNUM : UBIFS_MST_LNUM + 1));

	memcpy(c->mst_node, mst, UBIFS_MST_NODE_SZ);

	if (c->ro_mount) {
		/* Read-only mode. Keep a copy for switching to rw mode */
		c->rcvrd_mst_node = kmalloc(sz, GFP_KERNEL);
		if (!c->rcvrd_mst_node) {
			err = -ENOMEM;
			goto out_free;
		}
		memcpy(c->rcvrd_mst_node, c->mst_node, UBIFS_MST_NODE_SZ);
	} else {
		/* Write the recovered master node */
		c->max_sqnum = le64_to_cpu(mst->ch.sqnum) - 1;
		err = write_rcvrd_mst_node(c, c->mst_node);
		if (err)
			goto out_free;
	}

	vfree(buf2);
	vfree(buf1);

	return 0;

out_err:
	err = -EINVAL;
out_free:
	ubifs_err("failed to recover master node");
	if (mst1) {
		dbg_err("dumping first master node");
		dbg_dump_node(c, mst1);
	}
	if (mst2) {
		dbg_err("dumping second master node");
		dbg_dump_node(c, mst2);
	}
	vfree(buf2);
	vfree(buf1);
	return err;
}

/**
 * ubifs_write_rcvrd_mst_node - write the recovered master node.
 * @c: UBIFS file-system description object
 *
 * This function writes the master node that was recovered during mounting in
 * read-only mode and must now be written because we are remounting rw.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_write_rcvrd_mst_node(struct ubifs_info *c)
{
	int err;

	if (!c->rcvrd_mst_node)
		return 0;
	c->rcvrd_mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
	c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
	err = write_rcvrd_mst_node(c, c->rcvrd_mst_node);
	if (err)
		return err;
	kfree(c->rcvrd_mst_node);
	c->rcvrd_mst_node = NULL;
	return 0;
}

/**
 * is_last_write - determine if an offset was in the last write to a LEB.
 * @c: UBIFS file-system description object
 * @buf: buffer to check
 * @offs: offset to check
 *
 * This function returns %1 if @offs was in the last write to the LEB whose data
 * is in @buf, otherwise %0 is returned.  The determination is made by checking
 * for subsequent empty space starting from the next @c->min_io_size boundary.
 */
static int is_last_write(const struct ubifs_info *c, void *buf, int offs)
{
	int empty_offs, check_len;
	uint8_t *p;

	/*
	 * Round up to the next @c->min_io_size boundary i.e. @offs is in the
	 * last wbuf written. After that should be empty space.
	 */
	empty_offs = ALIGN(offs + 1, c->min_io_size);
	check_len = c->leb_size - empty_offs;
	p = buf + empty_offs - offs;
	return is_empty(p, check_len);
}

/**
 * clean_buf - clean the data from an LEB sitting in a buffer.
 * @c: UBIFS file-system description object
 * @buf: buffer to clean
 * @lnum: LEB number to clean
 * @offs: offset from which to clean
 * @len: length of buffer
 *
 * This function pads up to the next min_io_size boundary (if there is one) and
 * sets empty space to all 0xff. @buf, @offs and @len are updated to the next
 * @c->min_io_size boundary.
 */
static void clean_buf(const struct ubifs_info *c, void **buf, int lnum,
		      int *offs, int *len)
{
	int empty_offs, pad_len;

	lnum = lnum;
	dbg_rcvry("cleaning corruption at %d:%d", lnum, *offs);

	ubifs_assert(!(*offs & 7));
	empty_offs = ALIGN(*offs, c->min_io_size);
	pad_len = empty_offs - *offs;
	ubifs_pad(c, *buf, pad_len);
	*offs += pad_len;
	*buf += pad_len;
	*len -= pad_len;
	memset(*buf, 0xff, c->leb_size - empty_offs);
}

/**
 * no_more_nodes - determine if there are no more nodes in a buffer.
 * @c: UBIFS file-system description object
 * @buf: buffer to check
 * @len: length of buffer
 * @lnum: LEB number of the LEB from which @buf was read
 * @offs: offset from which @buf was read
 *
 * This function ensures that the corrupted node at @offs is the last thing
 * written to a LEB. This function returns %1 if more data is not found and
 * %0 if more data is found.
 */
static int no_more_nodes(const struct ubifs_info *c, void *buf, int len,
			int lnum, int offs)
{
	struct ubifs_ch *ch = buf;
	int skip, dlen = le32_to_cpu(ch->len);

	/* Check for empty space after the corrupt node's common header */
	skip = ALIGN(offs + UBIFS_CH_SZ, c->min_io_size) - offs;
	if (is_empty(buf + skip, len - skip))
		return 1;
	/*
	 * The area after the common header size is not empty, so the common
	 * header must be intact. Check it.
	 */
	if (ubifs_check_node(c, buf, lnum, offs, 1, 0) != -EUCLEAN) {
		dbg_rcvry("unexpected bad common header at %d:%d", lnum, offs);
		return 0;
	}
	/* Now we know the corrupt node's length we can skip over it */
	skip = ALIGN(offs + dlen, c->min_io_size) - offs;
	/* After which there should be empty space */
	if (is_empty(buf + skip, len - skip))
		return 1;
	dbg_rcvry("unexpected data at %d:%d", lnum, offs + skip);
	return 0;
}

/**
 * fix_unclean_leb - fix an unclean LEB.
 * @c: UBIFS file-system description object
 * @sleb: scanned LEB information
 * @start: offset where scan started
 */
static int fix_unclean_leb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
			   int start)
{
	int lnum = sleb->lnum, endpt = start;

	/* Get the end offset of the last node we are keeping */
	if (!list_empty(&sleb->nodes)) {
		struct ubifs_scan_node *snod;

		snod = list_entry(sleb->nodes.prev,
				  struct ubifs_scan_node, list);
		endpt = snod->offs + snod->len;
	}

	if (c->ro_mount && !c->remounting_rw) {
		/* Add to recovery list */
		struct ubifs_unclean_leb *ucleb;

		dbg_rcvry("need to fix LEB %d start %d endpt %d",
			  lnum, start, sleb->endpt);
		ucleb = kzalloc(sizeof(struct ubifs_unclean_leb), GFP_NOFS);
		if (!ucleb)
			return -ENOMEM;
		ucleb->lnum = lnum;
		ucleb->endpt = endpt;
		list_add_tail(&ucleb->list, &c->unclean_leb_list);
	} else {
		/* Write the fixed LEB back to flash */
		int err;

		dbg_rcvry("fixing LEB %d start %d endpt %d",
			  lnum, start, sleb->endpt);
		if (endpt == 0) {
			err = ubifs_leb_unmap(c, lnum);
			if (err)
				return err;
		} else {
			int len = ALIGN(endpt, c->min_io_size);

			if (start) {
				err = ubi_read(c->ubi, lnum, sleb->buf, 0,
					       start);
				if (err)
					return err;
			}
			/* Pad to min_io_size */
			if (len > endpt) {
				int pad_len = len - ALIGN(endpt, 8);

				if (pad_len > 0) {
					void *buf = sleb->buf + len - pad_len;

					ubifs_pad(c, buf, pad_len);
				}
			}
			err = ubi_leb_change(c->ubi, lnum, sleb->buf, len,
					     UBI_UNKNOWN);
			if (err)
				return err;
		}
	}
	return 0;
}

/**
 * drop_incomplete_group - drop nodes from an incomplete group.
 * @sleb: scanned LEB information
 * @offs: offset of dropped nodes is returned here
 *
 * This function returns %1 if nodes are dropped and %0 otherwise.
 */
static int drop_incomplete_group(struct ubifs_scan_leb *sleb, int *offs)
{
	int dropped = 0;

	while (!list_empty(&sleb->nodes)) {
		struct ubifs_scan_node *snod;
		struct ubifs_ch *ch;

		snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
				  list);
		ch = snod->node;
		if (ch->group_type != UBIFS_IN_NODE_GROUP)
			return dropped;
		dbg_rcvry("dropping node at %d:%d", sleb->lnum, snod->offs);
		*offs = snod->offs;
		list_del(&snod->list);
		kfree(snod);
		sleb->nodes_cnt -= 1;
		dropped = 1;
	}
	return dropped;
}

/**
 * ubifs_recover_leb - scan and recover a LEB.
 * @c: UBIFS file-system description object
 * @lnum: LEB number
 * @offs: offset
 * @sbuf: LEB-sized buffer to use
 * @grouped: nodes may be grouped for recovery
 *
 * This function does a scan of a LEB, but caters for errors that might have
 * been caused by the unclean unmount from which we are attempting to recover.
 * Returns %0 in case of success, %-EUCLEAN if an unrecoverable corruption is
 * found, and a negative error code in case of failure.
 */
struct ubifs_scan_leb *ubifs_recover_leb(struct ubifs_info *c, int lnum,
					 int offs, void *sbuf, int grouped)
{
	int err, len = c->leb_size - offs, need_clean = 0, quiet = 1;
	int empty_chkd = 0, start = offs;
	struct ubifs_scan_leb *sleb;
	void *buf = sbuf + offs;

	dbg_rcvry("%d:%d", lnum, offs);

	sleb = ubifs_start_scan(c, lnum, offs, sbuf);
	if (IS_ERR(sleb))
		return sleb;

	if (sleb->ecc)
		need_clean = 1;

	while (len >= 8) {
		int ret;

		dbg_scan("look at LEB %d:%d (%d bytes left)",
			 lnum, offs, len);

		cond_resched();

		/*
		 * Scan quietly until there is an error from which we cannot
		 * recover
		 */
		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);

		if (ret == SCANNED_A_NODE) {
			/* A valid node, and not a padding node */
			struct ubifs_ch *ch = buf;
			int node_len;

			err = ubifs_add_snod(c, sleb, buf, offs);
			if (err)
				goto error;
			node_len = ALIGN(le32_to_cpu(ch->len), 8);
			offs += node_len;
			buf += node_len;
			len -= node_len;
			continue;
		}

		if (ret > 0) {
			/* Padding bytes or a valid padding node */
			offs += ret;
			buf += ret;
			len -= ret;
			continue;
		}

		if (ret == SCANNED_EMPTY_SPACE) {
			if (!is_empty(buf, len)) {
				if (!is_last_write(c, buf, offs))
					break;
				clean_buf(c, &buf, lnum, &offs, &len);
				need_clean = 1;
			}
			empty_chkd = 1;
			break;
		}

		if (ret == SCANNED_GARBAGE || ret == SCANNED_A_BAD_PAD_NODE)
			if (is_last_write(c, buf, offs)) {
				clean_buf(c, &buf, lnum, &offs, &len);
				need_clean = 1;
				empty_chkd = 1;
				break;
			}

		if (ret == SCANNED_A_CORRUPT_NODE)
			if (no_more_nodes(c, buf, len, lnum, offs)) {
				clean_buf(c, &buf, lnum, &offs, &len);
				need_clean = 1;
				empty_chkd = 1;
				break;
			}

		if (quiet) {
			/* Redo the last scan but noisily */
			quiet = 0;
			continue;
		}

		switch (ret) {
		case SCANNED_GARBAGE:
			dbg_err("garbage");
			goto corrupted;
		case SCANNED_A_CORRUPT_NODE:
		case SCANNED_A_BAD_PAD_NODE:
			dbg_err("bad node");
			goto corrupted;
		default:
			dbg_err("unknown");
			err = -EINVAL;
			goto error;
		}
	}

	if (!empty_chkd && !is_empty(buf, len)) {
		if (is_last_write(c, buf, offs)) {
			clean_buf(c, &buf, lnum, &offs, &len);
			need_clean = 1;
		} else {
			int corruption = first_non_ff(buf, len);

			/*
			 * See header comment for this file for more
			 * explanations about the reasons we have this check.
			 */
			ubifs_err("corrupt empty space LEB %d:%d, corruption "
				  "starts at %d", lnum, offs, corruption);
			/* Make sure we dump interesting non-0xFF data */
			offs += corruption;
			buf += corruption;
			goto corrupted;
		}
	}

	/* Drop nodes from incomplete group */
	if (grouped && drop_incomplete_group(sleb, &offs)) {
		buf = sbuf + offs;
		len = c->leb_size - offs;
		clean_buf(c, &buf, lnum, &offs, &len);
		need_clean = 1;
	}

	if (offs % c->min_io_size) {
		clean_buf(c, &buf, lnum, &offs, &len);
		need_clean = 1;
	}

	ubifs_end_scan(c, sleb, lnum, offs);

	if (need_clean) {
		err = fix_unclean_leb(c, sleb, start);
		if (err)
			goto error;
	}

	return sleb;

corrupted:
	ubifs_scanned_corruption(c, lnum, offs, buf);
	err = -EUCLEAN;
error:
	ubifs_err("LEB %d scanning failed", lnum);
	ubifs_scan_destroy(sleb);
	return ERR_PTR(err);
}

/**
 * get_cs_sqnum - get commit start sequence number.
 * @c: UBIFS file-system description object
 * @lnum: LEB number of commit start node
 * @offs: offset of commit start node
 * @cs_sqnum: commit start sequence number is returned here
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int get_cs_sqnum(struct ubifs_info *c, int lnum, int offs,
			unsigned long long *cs_sqnum)
{
	struct ubifs_cs_node *cs_node = NULL;
	int err, ret;

	dbg_rcvry("at %d:%d", lnum, offs);
	cs_node = kmalloc(UBIFS_CS_NODE_SZ, GFP_KERNEL);
	if (!cs_node)
		return -ENOMEM;
	if (c->leb_size - offs < UBIFS_CS_NODE_SZ)
		goto out_err;
	err = ubi_read(c->ubi, lnum, (void *)cs_node, offs, UBIFS_CS_NODE_SZ);
	if (err && err != -EBADMSG)
		goto out_free;
	ret = ubifs_scan_a_node(c, cs_node, UBIFS_CS_NODE_SZ, lnum, offs, 0);
	if (ret != SCANNED_A_NODE) {
		dbg_err("Not a valid node");
		goto out_err;
	}
	if (cs_node->ch.node_type != UBIFS_CS_NODE) {
		dbg_err("Node a CS node, type is %d", cs_node->ch.node_type);
		goto out_err;
	}
	if (le64_to_cpu(cs_node->cmt_no) != c->cmt_no) {
		dbg_err("CS node cmt_no %llu != current cmt_no %llu",
			(unsigned long long)le64_to_cpu(cs_node->cmt_no),
			c->cmt_no);
		goto out_err;
	}
	*cs_sqnum = le64_to_cpu(cs_node->ch.sqnum);
	dbg_rcvry("commit start sqnum %llu", *cs_sqnum);
	kfree(cs_node);
	return 0;

out_err:
	err = -EINVAL;
out_free:
	ubifs_err("failed to get CS sqnum");
	kfree(cs_node);
	return err;
}

/**
 * ubifs_recover_log_leb - scan and recover a log LEB.
 * @c: UBIFS file-system description object
 * @lnum: LEB number
 * @offs: offset
 * @sbuf: LEB-sized buffer to use
 *
 * This function does a scan of a LEB, but caters for errors that might have
 * been caused by unclean reboots from which we are attempting to recover
 * (assume that only the last log LEB can be corrupted by an unclean reboot).
 *
 * This function returns %0 on success and a negative error code on failure.
 */
struct ubifs_scan_leb *ubifs_recover_log_leb(struct ubifs_info *c, int lnum,
					     int offs, void *sbuf)
{
	struct ubifs_scan_leb *sleb;
	int next_lnum;

	dbg_rcvry("LEB %d", lnum);
	next_lnum = lnum + 1;
	if (next_lnum >= UBIFS_LOG_LNUM + c->log_lebs)
		next_lnum = UBIFS_LOG_LNUM;
	if (next_lnum != c->ltail_lnum) {
		/*
		 * We can only recover at the end of the log, so check that the
		 * next log LEB is empty or out of date.
		 */
		sleb = ubifs_scan(c, next_lnum, 0, sbuf, 0);
		if (IS_ERR(sleb))
			return sleb;
		if (sleb->nodes_cnt) {
			struct ubifs_scan_node *snod;
			unsigned long long cs_sqnum = c->cs_sqnum;

			snod = list_entry(sleb->nodes.next,
					  struct ubifs_scan_node, list);
			if (cs_sqnum == 0) {
				int err;

				err = get_cs_sqnum(c, lnum, offs, &cs_sqnum);
				if (err) {
					ubifs_scan_destroy(sleb);
					return ERR_PTR(err);
				}
			}
			if (snod->sqnum > cs_sqnum) {
				ubifs_err("unrecoverable log corruption "
					  "in LEB %d", lnum);
				ubifs_scan_destroy(sleb);
				return ERR_PTR(-EUCLEAN);
			}
		}
		ubifs_scan_destroy(sleb);
	}
	return ubifs_recover_leb(c, lnum, offs, sbuf, 0);
}

/**
 * recover_head - recover a head.
 * @c: UBIFS file-system description object
 * @lnum: LEB number of head to recover
 * @offs: offset of head to recover
 * @sbuf: LEB-sized buffer to use
 *
 * This function ensures that there is no data on the flash at a head location.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int recover_head(const struct ubifs_info *c, int lnum, int offs,
			void *sbuf)
{
	int len, err;

	if (c->min_io_size > 1)
		len = c->min_io_size;
	else
		len = 512;
	if (offs + len > c->leb_size)
		len = c->leb_size - offs;

	if (!len)
		return 0;

	/* Read at the head location and check it is empty flash */
	err = ubi_read(c->ubi, lnum, sbuf, offs, len);
	if (err || !is_empty(sbuf, len)) {
		dbg_rcvry("cleaning head at %d:%d", lnum, offs);
		if (offs == 0)
			return ubifs_leb_unmap(c, lnum);
		err = ubi_read(c->ubi, lnum, sbuf, 0, offs);
		if (err)
			return err;
		return ubi_leb_change(c->ubi, lnum, sbuf, offs, UBI_UNKNOWN);
	}

	return 0;
}

/**
 * ubifs_recover_inl_heads - recover index and LPT heads.
 * @c: UBIFS file-system description object
 * @sbuf: LEB-sized buffer to use
 *
 * This function ensures that there is no data on the flash at the index and
 * LPT head locations.
 *
 * This deals with the recovery of a half-completed journal commit. UBIFS is
 * careful never to overwrite the last version of the index or the LPT. Because
 * the index and LPT are wandering trees, data from a half-completed commit will
 * not be referenced anywhere in UBIFS. The data will be either in LEBs that are
 * assumed to be empty and will be unmapped anyway before use, or in the index
 * and LPT heads.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_recover_inl_heads(const struct ubifs_info *c, void *sbuf)
{
	int err;

	ubifs_assert(!c->ro_mount || c->remounting_rw);

	dbg_rcvry("checking index head at %d:%d", c->ihead_lnum, c->ihead_offs);
	err = recover_head(c, c->ihead_lnum, c->ihead_offs, sbuf);
	if (err)
		return err;

	dbg_rcvry("checking LPT head at %d:%d", c->nhead_lnum, c->nhead_offs);
	err = recover_head(c, c->nhead_lnum, c->nhead_offs, sbuf);
	if (err)
		return err;

	return 0;
}

/**
 *  clean_an_unclean_leb - read and write a LEB to remove corruption.
 * @c: UBIFS file-system description object
 * @ucleb: unclean LEB information
 * @sbuf: LEB-sized buffer to use
 *
 * This function reads a LEB up to a point pre-determined by the mount recovery,
 * checks the nodes, and writes the result back to the flash, thereby cleaning
 * off any following corruption, or non-fatal ECC errors.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int clean_an_unclean_leb(const struct ubifs_info *c,
				struct ubifs_unclean_leb *ucleb, void *sbuf)
{
	int err, lnum = ucleb->lnum, offs = 0, len = ucleb->endpt, quiet = 1;
	void *buf = sbuf;

	dbg_rcvry("LEB %d len %d", lnum, len);

	if (len == 0) {
		/* Nothing to read, just unmap it */
		err = ubifs_leb_unmap(c, lnum);
		if (err)
			return err;
		return 0;
	}

	err = ubi_read(c->ubi, lnum, buf, offs, len);
	if (err && err != -EBADMSG)
		return err;

	while (len >= 8) {
		int ret;

		cond_resched();

		/* Scan quietly until there is an error */
		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);

		if (ret == SCANNED_A_NODE) {
			/* A valid node, and not a padding node */
			struct ubifs_ch *ch = buf;
			int node_len;

			node_len = ALIGN(le32_to_cpu(ch->len), 8);
			offs += node_len;
			buf += node_len;
			len -= node_len;
			continue;
		}

		if (ret > 0) {
			/* Padding bytes or a valid padding node */
			offs += ret;
			buf += ret;
			len -= ret;
			continue;
		}

		if (ret == SCANNED_EMPTY_SPACE) {
			ubifs_err("unexpected empty space at %d:%d",
				  lnum, offs);
			return -EUCLEAN;
		}

		if (quiet) {
			/* Redo the last scan but noisily */
			quiet = 0;
			continue;
		}

		ubifs_scanned_corruption(c, lnum, offs, buf);
		return -EUCLEAN;
	}

	/* Pad to min_io_size */
	len = ALIGN(ucleb->endpt, c->min_io_size);
	if (len > ucleb->endpt) {
		int pad_len = len - ALIGN(ucleb->endpt, 8);

		if (pad_len > 0) {
			buf = c->sbuf + len - pad_len;
			ubifs_pad(c, buf, pad_len);
		}
	}

	/* Write back the LEB atomically */
	err = ubi_leb_change(c->ubi, lnum, sbuf, len, UBI_UNKNOWN);
	if (err)
		return err;

	dbg_rcvry("cleaned LEB %d", lnum);

	return 0;
}

/**
 * ubifs_clean_lebs - clean LEBs recovered during read-only mount.
 * @c: UBIFS file-system description object
 * @sbuf: LEB-sized buffer to use
 *
 * This function cleans a LEB identified during recovery that needs to be
 * written but was not because UBIFS was mounted read-only. This happens when
 * remounting to read-write mode.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_clean_lebs(const struct ubifs_info *c, void *sbuf)
{
	dbg_rcvry("recovery");
	while (!list_empty(&c->unclean_leb_list)) {
		struct ubifs_unclean_leb *ucleb;
		int err;

		ucleb = list_entry(c->unclean_leb_list.next,
				   struct ubifs_unclean_leb, list);
		err = clean_an_unclean_leb(c, ucleb, sbuf);
		if (err)
			return err;
		list_del(&ucleb->list);
		kfree(ucleb);
	}
	return 0;
}

/**
 * ubifs_rcvry_gc_commit - recover the GC LEB number and run the commit.
 * @c: UBIFS file-system description object
 *
 * Out-of-place garbage collection requires always one empty LEB with which to
 * start garbage collection. The LEB number is recorded in c->gc_lnum and is
 * written to the master node on unmounting. In the case of an unclean unmount
 * the value of gc_lnum recorded in the master node is out of date and cannot
 * be used. Instead, recovery must allocate an empty LEB for this purpose.
 * However, there may not be enough empty space, in which case it must be
 * possible to GC the dirtiest LEB into the GC head LEB.
 *
 * This function also runs the commit which causes the TNC updates from
 * size-recovery and orphans to be written to the flash. That is important to
 * ensure correct replay order for subsequent mounts.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_rcvry_gc_commit(struct ubifs_info *c)
{
	struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
	struct ubifs_lprops lp;
	int lnum, err;

	c->gc_lnum = -1;
	if (wbuf->lnum == -1) {
		dbg_rcvry("no GC head LEB");
		goto find_free;
	}
	/*
	 * See whether the used space in the dirtiest LEB fits in the GC head
	 * LEB.
	 */
	if (wbuf->offs == c->leb_size) {
		dbg_rcvry("no room in GC head LEB");
		goto find_free;
	}
	err = ubifs_find_dirty_leb(c, &lp, wbuf->offs, 2);
	if (err) {
		/*
		 * There are no dirty or empty LEBs subject to here being
		 * enough for the index. Try to use
		 * 'ubifs_find_free_leb_for_idx()', which will return any empty
		 * LEBs (ignoring index requirements). If the index then
		 * doesn't have enough LEBs the recovery commit will fail -
		 * which is the  same result anyway i.e. recovery fails. So
		 * there is no problem ignoring index  requirements and just
		 * grabbing a free LEB since we have already established there
		 * is not a dirty LEB we could have used instead.
		 */
		if (err == -ENOSPC) {
			dbg_rcvry("could not find a dirty LEB");
			goto find_free;
		}
		return err;
	}
	ubifs_assert(!(lp.flags & LPROPS_INDEX));
	lnum = lp.lnum;
	if (lp.free + lp.dirty == c->leb_size) {
		/* An empty LEB was returned */
		if (lp.free != c->leb_size) {
			err = ubifs_change_one_lp(c, lnum, c->leb_size,
						  0, 0, 0, 0);
			if (err)
				return err;
		}
		err = ubifs_leb_unmap(c, lnum);
		if (err)
			return err;
		c->gc_lnum = lnum;
		dbg_rcvry("allocated LEB %d for GC", lnum);
		/* Run the commit */
		dbg_rcvry("committing");
		return ubifs_run_commit(c);
	}
	/*
	 * There was no empty LEB so the used space in the dirtiest LEB must fit
	 * in the GC head LEB.
	 */
	if (lp.free + lp.dirty < wbuf->offs) {
		dbg_rcvry("LEB %d doesn't fit in GC head LEB %d:%d",
			  lnum, wbuf->lnum, wbuf->offs);
		err = ubifs_return_leb(c, lnum);
		if (err)
			return err;
		goto find_free;
	}
	/*
	 * We run the commit before garbage collection otherwise subsequent
	 * mounts will see the GC and orphan deletion in a different order.
	 */
	dbg_rcvry("committing");
	err = ubifs_run_commit(c);
	if (err)
		return err;
	/*
	 * The data in the dirtiest LEB fits in the GC head LEB, so do the GC
	 * - use locking to keep 'ubifs_assert()' happy.
	 */
	dbg_rcvry("GC'ing LEB %d", lnum);
	mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
	err = ubifs_garbage_collect_leb(c, &lp);
	if (err >= 0) {
		int err2 = ubifs_wbuf_sync_nolock(wbuf);

		if (err2)
			err = err2;
	}
	mutex_unlock(&wbuf->io_mutex);
	if (err < 0) {
		dbg_err("GC failed, error %d", err);
		if (err == -EAGAIN)
			err = -EINVAL;
		return err;
	}
	if (err != LEB_RETAINED) {
		dbg_err("GC returned %d", err);
		return -EINVAL;
	}
	err = ubifs_leb_unmap(c, c->gc_lnum);
	if (err)
		return err;
	dbg_rcvry("allocated LEB %d for GC", lnum);
	return 0;

find_free:
	/*
	 * There is no GC head LEB or the free space in the GC head LEB is too
	 * small, or there are not dirty LEBs. Allocate gc_lnum by calling
	 * 'ubifs_find_free_leb_for_idx()' so GC is not run.
	 */
	lnum = ubifs_find_free_leb_for_idx(c);
	if (lnum < 0) {
		dbg_err("could not find an empty LEB");
		return lnum;
	}
	/* And reset the index flag */
	err = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
				  LPROPS_INDEX, 0);
	if (err)
		return err;
	c->gc_lnum = lnum;
	dbg_rcvry("allocated LEB %d for GC", lnum);
	/* Run the commit */
	dbg_rcvry("committing");
	return ubifs_run_commit(c);
}

/**
 * struct size_entry - inode size information for recovery.
 * @rb: link in the RB-tree of sizes
 * @inum: inode number
 * @i_size: size on inode
 * @d_size: maximum size based on data nodes
 * @exists: indicates whether the inode exists
 * @inode: inode if pinned in memory awaiting rw mode to fix it
 */
struct size_entry {
	struct rb_node rb;
	ino_t inum;
	loff_t i_size;
	loff_t d_size;
	int exists;
	struct inode *inode;
};

/**
 * add_ino - add an entry to the size tree.
 * @c: UBIFS file-system description object
 * @inum: inode number
 * @i_size: size on inode
 * @d_size: maximum size based on data nodes
 * @exists: indicates whether the inode exists
 */
static int add_ino(struct ubifs_info *c, ino_t inum, loff_t i_size,
		   loff_t d_size, int exists)
{
	struct rb_node **p = &c->size_tree.rb_node, *parent = NULL;
	struct size_entry *e;

	while (*p) {
		parent = *p;
		e = rb_entry(parent, struct size_entry, rb);
		if (inum < e->inum)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
	}

	e = kzalloc(sizeof(struct size_entry), GFP_KERNEL);
	if (!e)
		return -ENOMEM;

	e->inum = inum;
	e->i_size = i_size;
	e->d_size = d_size;
	e->exists = exists;

	rb_link_node(&e->rb, parent, p);
	rb_insert_color(&e->rb, &c->size_tree);

	return 0;
}

/**
 * find_ino - find an entry on the size tree.
 * @c: UBIFS file-system description object
 * @inum: inode number
 */
static struct size_entry *find_ino(struct ubifs_info *c, ino_t inum)
{
	struct rb_node *p = c->size_tree.rb_node;
	struct size_entry *e;

	while (p) {
		e = rb_entry(p, struct size_entry, rb);
		if (inum < e->inum)
			p = p->rb_left;
		else if (inum > e->inum)
			p = p->rb_right;
		else
			return e;
	}
	return NULL;
}

/**
 * remove_ino - remove an entry from the size tree.
 * @c: UBIFS file-system description object
 * @inum: inode number
 */
static void remove_ino(struct ubifs_info *c, ino_t inum)
{
	struct size_entry *e = find_ino(c, inum);

	if (!e)
		return;
	rb_erase(&e->rb, &c->size_tree);
	kfree(e);
}

/**
 * ubifs_destroy_size_tree - free resources related to the size tree.
 * @c: UBIFS file-system description object
 */
void ubifs_destroy_size_tree(struct ubifs_info *c)
{
	struct rb_node *this = c->size_tree.rb_node;
	struct size_entry *e;

	while (this) {
		if (this->rb_left) {
			this = this->rb_left;
			continue;
		} else if (this->rb_right) {
			this = this->rb_right;
			continue;
		}
		e = rb_entry(this, struct size_entry, rb);
		if (e->inode)
			iput(e->inode);
		this = rb_parent(this);
		if (this) {
			if (this->rb_left == &e->rb)
				this->rb_left = NULL;
			else
				this->rb_right = NULL;
		}
		kfree(e);
	}
	c->size_tree = RB_ROOT;
}

/**
 * ubifs_recover_size_accum - accumulate inode sizes for recovery.
 * @c: UBIFS file-system description object
 * @key: node key
 * @deletion: node is for a deletion
 * @new_size: inode size
 *
 * This function has two purposes:
 *     1) to ensure there are no data nodes that fall outside the inode size
 *     2) to ensure there are no data nodes for inodes that do not exist
 * To accomplish those purposes, a rb-tree is constructed containing an entry
 * for each inode number in the journal that has not been deleted, and recording
 * the size from the inode node, the maximum size of any data node (also altered
 * by truncations) and a flag indicating a inode number for which no inode node
 * was present in the journal.
 *
 * Note that there is still the possibility that there are data nodes that have
 * been committed that are beyond the inode size, however the only way to find
 * them would be to scan the entire index. Alternatively, some provision could
 * be made to record the size of inodes at the start of commit, which would seem
 * very cumbersome for a scenario that is quite unlikely and the only negative
 * consequence of which is wasted space.
 *
 * This functions returns %0 on success and a negative error code on failure.
 */
int ubifs_recover_size_accum(struct ubifs_info *c, union ubifs_key *key,
			     int deletion, loff_t new_size)
{
	ino_t inum = key_inum(c, key);
	struct size_entry *e;
	int err;

	switch (key_type(c, key)) {
	case UBIFS_INO_KEY:
		if (deletion)
			remove_ino(c, inum);
		else {
			e = find_ino(c, inum);
			if (e) {
				e->i_size = new_size;
				e->exists = 1;
			} else {
				err = add_ino(c, inum, new_size, 0, 1);
				if (err)
					return err;
			}
		}
		break;
	case UBIFS_DATA_KEY:
		e = find_ino(c, inum);
		if (e) {
			if (new_size > e->d_size)
				e->d_size = new_size;
		} else {
			err = add_ino(c, inum, 0, new_size, 0);
			if (err)
				return err;
		}
		break;
	case UBIFS_TRUN_KEY:
		e = find_ino(c, inum);
		if (e)
			e->d_size = new_size;
		break;
	}
	return 0;
}

/**
 * fix_size_in_place - fix inode size in place on flash.
 * @c: UBIFS file-system description object
 * @e: inode size information for recovery
 */
static int fix_size_in_place(struct ubifs_info *c, struct size_entry *e)
{
	struct ubifs_ino_node *ino = c->sbuf;
	unsigned char *p;
	union ubifs_key key;
	int err, lnum, offs, len;
	loff_t i_size;
	uint32_t crc;

	/* Locate the inode node LEB number and offset */
	ino_key_init(c, &key, e->inum);
	err = ubifs_tnc_locate(c, &key, ino, &lnum, &offs);
	if (err)
		goto out;
	/*
	 * If the size recorded on the inode node is greater than the size that
	 * was calculated from nodes in the journal then don't change the inode.
	 */
	i_size = le64_to_cpu(ino->size);
	if (i_size >= e->d_size)
		return 0;
	/* Read the LEB */
	err = ubi_read(c->ubi, lnum, c->sbuf, 0, c->leb_size);
	if (err)
		goto out;
	/* Change the size field and recalculate the CRC */
	ino = c->sbuf + offs;
	ino->size = cpu_to_le64(e->d_size);
	len = le32_to_cpu(ino->ch.len);
	crc = crc32(UBIFS_CRC32_INIT, (void *)ino + 8, len - 8);
	ino->ch.crc = cpu_to_le32(crc);
	/* Work out where data in the LEB ends and free space begins */
	p = c->sbuf;
	len = c->leb_size - 1;
	while (p[len] == 0xff)
		len -= 1;
	len = ALIGN(len + 1, c->min_io_size);
	/* Atomically write the fixed LEB back again */
	err = ubi_leb_change(c->ubi, lnum, c->sbuf, len, UBI_UNKNOWN);
	if (err)
		goto out;
	dbg_rcvry("inode %lu at %d:%d size %lld -> %lld ",
		  (unsigned long)e->inum, lnum, offs, i_size, e->d_size);
	return 0;

out:
	ubifs_warn("inode %lu failed to fix size %lld -> %lld error %d",
		   (unsigned long)e->inum, e->i_size, e->d_size, err);
	return err;
}

/**
 * ubifs_recover_size - recover inode size.
 * @c: UBIFS file-system description object
 *
 * This function attempts to fix inode size discrepancies identified by the
 * 'ubifs_recover_size_accum()' function.
 *
 * This functions returns %0 on success and a negative error code on failure.
 */
int ubifs_recover_size(struct ubifs_info *c)
{
	struct rb_node *this = rb_first(&c->size_tree);

	while (this) {
		struct size_entry *e;
		int err;

		e = rb_entry(this, struct size_entry, rb);
		if (!e->exists) {
			union ubifs_key key;

			ino_key_init(c, &key, e->inum);
			err = ubifs_tnc_lookup(c, &key, c->sbuf);
			if (err && err != -ENOENT)
				return err;
			if (err == -ENOENT) {
				/* Remove data nodes that have no inode */
				dbg_rcvry("removing ino %lu",
					  (unsigned long)e->inum);
				err = ubifs_tnc_remove_ino(c, e->inum);
				if (err)
					return err;
			} else {
				struct ubifs_ino_node *ino = c->sbuf;

				e->exists = 1;
				e->i_size = le64_to_cpu(ino->size);
			}
		}
		if (e->exists && e->i_size < e->d_size) {
			if (!e->inode && c->ro_mount) {
				/* Fix the inode size and pin it in memory */
				struct inode *inode;

				inode = ubifs_iget(c->vfs_sb, e->inum);
				if (IS_ERR(inode))
					return PTR_ERR(inode);
				if (inode->i_size < e->d_size) {
					dbg_rcvry("ino %lu size %lld -> %lld",
						  (unsigned long)e->inum,
						  e->d_size, inode->i_size);
					inode->i_size = e->d_size;
					ubifs_inode(inode)->ui_size = e->d_size;
					e->inode = inode;
					this = rb_next(this);
					continue;
				}
				iput(inode);
			} else {
				/* Fix the size in place */
				err = fix_size_in_place(c, e);
				if (err)
					return err;
				if (e->inode)
					iput(e->inode);
			}
		}
		this = rb_next(this);
		rb_erase(&e->rb, &c->size_tree);
		kfree(e);
	}
	return 0;
}