aboutsummaryrefslogtreecommitdiff
path: root/drivers/mtd/ubi/io.c
blob: 4ac11df7b048d3a24684744c4f399f13b81653ea (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
/*
 * Copyright (c) International Business Machines Corp., 2006
 * Copyright (c) Nokia Corporation, 2006, 2007
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Author: Artem Bityutskiy (Битюцкий Артём)
 */

/*
 * UBI input/output unit.
 *
 * This unit provides a uniform way to work with all kinds of the underlying
 * MTD devices. It also implements handy functions for reading and writing UBI
 * headers.
 *
 * We are trying to have a paranoid mindset and not to trust to what we read
 * from the flash media in order to be more secure and robust. So this unit
 * validates every single header it reads from the flash media.
 *
 * Some words about how the eraseblock headers are stored.
 *
 * The erase counter header is always stored at offset zero. By default, the
 * VID header is stored after the EC header at the closest aligned offset
 * (i.e. aligned to the minimum I/O unit size). Data starts next to the VID
 * header at the closest aligned offset. But this default layout may be
 * changed. For example, for different reasons (e.g., optimization) UBI may be
 * asked to put the VID header at further offset, and even at an unaligned
 * offset. Of course, if the offset of the VID header is unaligned, UBI adds
 * proper padding in front of it. Data offset may also be changed but it has to
 * be aligned.
 *
 * About minimal I/O units. In general, UBI assumes flash device model where
 * there is only one minimal I/O unit size. E.g., in case of NOR flash it is 1,
 * in case of NAND flash it is a NAND page, etc. This is reported by MTD in the
 * @ubi->mtd->writesize field. But as an exception, UBI admits of using another
 * (smaller) minimal I/O unit size for EC and VID headers to make it possible
 * to do different optimizations.
 *
 * This is extremely useful in case of NAND flashes which admit of several
 * write operations to one NAND page. In this case UBI can fit EC and VID
 * headers at one NAND page. Thus, UBI may use "sub-page" size as the minimal
 * I/O unit for the headers (the @ubi->hdrs_min_io_size field). But it still
 * reports NAND page size (@ubi->min_io_size) as a minimal I/O unit for the UBI
 * users.
 *
 * Example: some Samsung NANDs with 2KiB pages allow 4x 512-byte writes, so
 * although the minimal I/O unit is 2K, UBI uses 512 bytes for EC and VID
 * headers.
 *
 * Q: why not just to treat sub-page as a minimal I/O unit of this flash
 * device, e.g., make @ubi->min_io_size = 512 in the example above?
 *
 * A: because when writing a sub-page, MTD still writes a full 2K page but the
 * bytes which are no relevant to the sub-page are 0xFF. So, basically, writing
 * 4x512 sub-pages is 4 times slower then writing one 2KiB NAND page. Thus, we
 * prefer to use sub-pages only for EV and VID headers.
 *
 * As it was noted above, the VID header may start at a non-aligned offset.
 * For example, in case of a 2KiB page NAND flash with a 512 bytes sub-page,
 * the VID header may reside at offset 1984 which is the last 64 bytes of the
 * last sub-page (EC header is always at offset zero). This causes some
 * difficulties when reading and writing VID headers.
 *
 * Suppose we have a 64-byte buffer and we read a VID header at it. We change
 * the data and want to write this VID header out. As we can only write in
 * 512-byte chunks, we have to allocate one more buffer and copy our VID header
 * to offset 448 of this buffer.
 *
 * The I/O unit does the following trick in order to avoid this extra copy.
 * It always allocates a @ubi->vid_hdr_alsize bytes buffer for the VID header
 * and returns a pointer to offset @ubi->vid_hdr_shift of this buffer. When the
 * VID header is being written out, it shifts the VID header pointer back and
 * writes the whole sub-page.
 */

#include <linux/crc32.h>
#include <linux/err.h>
#include "ubi.h"

#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
static int paranoid_check_not_bad(const struct ubi_device *ubi, int pnum);
static int paranoid_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum);
static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
				 const struct ubi_ec_hdr *ec_hdr);
static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum);
static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
				  const struct ubi_vid_hdr *vid_hdr);
static int paranoid_check_all_ff(struct ubi_device *ubi, int pnum, int offset,
				 int len);
#else
#define paranoid_check_not_bad(ubi, pnum) 0
#define paranoid_check_peb_ec_hdr(ubi, pnum)  0
#define paranoid_check_ec_hdr(ubi, pnum, ec_hdr)  0
#define paranoid_check_peb_vid_hdr(ubi, pnum) 0
#define paranoid_check_vid_hdr(ubi, pnum, vid_hdr) 0
#define paranoid_check_all_ff(ubi, pnum, offset, len) 0
#endif

/**
 * ubi_io_read - read data from a physical eraseblock.
 * @ubi: UBI device description object
 * @buf: buffer where to store the read data
 * @pnum: physical eraseblock number to read from
 * @offset: offset within the physical eraseblock from where to read
 * @len: how many bytes to read
 *
 * This function reads data from offset @offset of physical eraseblock @pnum
 * and stores the read data in the @buf buffer. The following return codes are
 * possible:
 *
 * o %0 if all the requested data were successfully read;
 * o %UBI_IO_BITFLIPS if all the requested data were successfully read, but
 *   correctable bit-flips were detected; this is harmless but may indicate
 *   that this eraseblock may become bad soon (but do not have to);
 * o %-EBADMSG if the MTD subsystem reported about data integrity problems, for
 *   example it can be an ECC error in case of NAND; this most probably means
 *   that the data is corrupted;
 * o %-EIO if some I/O error occurred;
 * o other negative error codes in case of other errors.
 */
int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
		int len)
{
	int err, retries = 0;
	size_t read;
	loff_t addr;

	dbg_io("read %d bytes from PEB %d:%d", len, pnum, offset);

	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
	ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
	ubi_assert(len > 0);

	err = paranoid_check_not_bad(ubi, pnum);
	if (err)
		return err > 0 ? -EINVAL : err;

	addr = (loff_t)pnum * ubi->peb_size + offset;
retry:
	err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
	if (err) {
		if (err == -EUCLEAN) {
			/*
			 * -EUCLEAN is reported if there was a bit-flip which
			 * was corrected, so this is harmless.
			 */
			ubi_msg("fixable bit-flip detected at PEB %d", pnum);
			ubi_assert(len == read);
			return UBI_IO_BITFLIPS;
		}

		if (read != len && retries++ < UBI_IO_RETRIES) {
			dbg_io("error %d while reading %d bytes from PEB %d:%d, "
			       "read only %zd bytes, retry",
			       err, len, pnum, offset, read);
			yield();
			goto retry;
		}

		ubi_err("error %d while reading %d bytes from PEB %d:%d, "
			"read %zd bytes", err, len, pnum, offset, read);
		ubi_dbg_dump_stack();

		/*
		 * The driver should never return -EBADMSG if it failed to read
		 * all the requested data. But some buggy drivers might do
		 * this, so we change it to -EIO.
		 */
		if (read != len && err == -EBADMSG) {
			ubi_assert(0);
			err = -EIO;
		}
	} else {
		ubi_assert(len == read);

		if (ubi_dbg_is_bitflip()) {
			dbg_msg("bit-flip (emulated)");
			err = UBI_IO_BITFLIPS;
		}
	}

	return err;
}

/**
 * ubi_io_write - write data to a physical eraseblock.
 * @ubi: UBI device description object
 * @buf: buffer with the data to write
 * @pnum: physical eraseblock number to write to
 * @offset: offset within the physical eraseblock where to write
 * @len: how many bytes to write
 *
 * This function writes @len bytes of data from buffer @buf to offset @offset
 * of physical eraseblock @pnum. If all the data were successfully written,
 * zero is returned. If an error occurred, this function returns a negative
 * error code. If %-EIO is returned, the physical eraseblock most probably went
 * bad.
 *
 * Note, in case of an error, it is possible that something was still written
 * to the flash media, but may be some garbage.
 */
int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
		 int len)
{
	int err;
	size_t written;
	loff_t addr;

	dbg_io("write %d bytes to PEB %d:%d", len, pnum, offset);

	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
	ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
	ubi_assert(offset % ubi->hdrs_min_io_size == 0);
	ubi_assert(len > 0 && len % ubi->hdrs_min_io_size == 0);

	if (ubi->ro_mode) {
		ubi_err("read-only mode");
		return -EROFS;
	}

	/* The below has to be compiled out if paranoid checks are disabled */

	err = paranoid_check_not_bad(ubi, pnum);
	if (err)
		return err > 0 ? -EINVAL : err;

	/* The area we are writing to has to contain all 0xFF bytes */
	err = paranoid_check_all_ff(ubi, pnum, offset, len);
	if (err)
		return err > 0 ? -EINVAL : err;

	if (offset >= ubi->leb_start) {
		/*
		 * We write to the data area of the physical eraseblock. Make
		 * sure it has valid EC and VID headers.
		 */
		err = paranoid_check_peb_ec_hdr(ubi, pnum);
		if (err)
			return err > 0 ? -EINVAL : err;
		err = paranoid_check_peb_vid_hdr(ubi, pnum);
		if (err)
			return err > 0 ? -EINVAL : err;
	}

	if (ubi_dbg_is_write_failure()) {
		dbg_err("cannot write %d bytes to PEB %d:%d "
			"(emulated)", len, pnum, offset);
		ubi_dbg_dump_stack();
		return -EIO;
	}

	addr = (loff_t)pnum * ubi->peb_size + offset;
	err = ubi->mtd->write(ubi->mtd, addr, len, &written, buf);
	if (err) {
		ubi_err("error %d while writing %d bytes to PEB %d:%d, written"
			" %zd bytes", err, len, pnum, offset, written);
		ubi_dbg_dump_stack();
	} else
		ubi_assert(written == len);

	return err;
}

/**
 * erase_callback - MTD erasure call-back.
 * @ei: MTD erase information object.
 *
 * Note, even though MTD erase interface is asynchronous, all the current
 * implementations are synchronous anyway.
 */
static void erase_callback(struct erase_info *ei)
{
	wake_up_interruptible((wait_queue_head_t *)ei->priv);
}

/**
 * do_sync_erase - synchronously erase a physical eraseblock.
 * @ubi: UBI device description object
 * @pnum: the physical eraseblock number to erase
 *
 * This function synchronously erases physical eraseblock @pnum and returns
 * zero in case of success and a negative error code in case of failure. If
 * %-EIO is returned, the physical eraseblock most probably went bad.
 */
static int do_sync_erase(struct ubi_device *ubi, int pnum)
{
	int err, retries = 0;
	struct erase_info ei;
	wait_queue_head_t wq;

	dbg_io("erase PEB %d", pnum);

retry:
	init_waitqueue_head(&wq);
	memset(&ei, 0, sizeof(struct erase_info));

	ei.mtd      = ubi->mtd;
	ei.addr     = (loff_t)pnum * ubi->peb_size;
	ei.len      = ubi->peb_size;
	ei.callback = erase_callback;
	ei.priv     = (unsigned long)&wq;

	err = ubi->mtd->erase(ubi->mtd, &ei);
	if (err) {
		if (retries++ < UBI_IO_RETRIES) {
			dbg_io("error %d while erasing PEB %d, retry",
			       err, pnum);
			yield();
			goto retry;
		}
		ubi_err("cannot erase PEB %d, error %d", pnum, err);
		ubi_dbg_dump_stack();
		return err;
	}

	err = wait_event_interruptible(wq, ei.state == MTD_ERASE_DONE ||
					   ei.state == MTD_ERASE_FAILED);
	if (err) {
		ubi_err("interrupted PEB %d erasure", pnum);
		return -EINTR;
	}

	if (ei.state == MTD_ERASE_FAILED) {
		if (retries++ < UBI_IO_RETRIES) {
			dbg_io("error while erasing PEB %d, retry", pnum);
			yield();
			goto retry;
		}
		ubi_err("cannot erase PEB %d", pnum);
		ubi_dbg_dump_stack();
		return -EIO;
	}

	err = paranoid_check_all_ff(ubi, pnum, 0, ubi->peb_size);
	if (err)
		return err > 0 ? -EINVAL : err;

	if (ubi_dbg_is_erase_failure() && !err) {
		dbg_err("cannot erase PEB %d (emulated)", pnum);
		return -EIO;
	}

	return 0;
}

/**
 * check_pattern - check if buffer contains only a certain byte pattern.
 * @buf: buffer to check
 * @patt: the pattern to check
 * @size: buffer size in bytes
 *
 * This function returns %1 in there are only @patt bytes in @buf, and %0 if
 * something else was also found.
 */
static int check_pattern(const void *buf, uint8_t patt, int size)
{
	int i;

	for (i = 0; i < size; i++)
		if (((const uint8_t *)buf)[i] != patt)
			return 0;
	return 1;
}

/* Patterns to write to a physical eraseblock when torturing it */
static uint8_t patterns[] = {0xa5, 0x5a, 0x0};

/**
 * torture_peb - test a supposedly bad physical eraseblock.
 * @ubi: UBI device description object
 * @pnum: the physical eraseblock number to test
 *
 * This function returns %-EIO if the physical eraseblock did not pass the
 * test, a positive number of erase operations done if the test was
 * successfully passed, and other negative error codes in case of other errors.
 */
static int torture_peb(struct ubi_device *ubi, int pnum)
{
	int err, i, patt_count;

	patt_count = ARRAY_SIZE(patterns);
	ubi_assert(patt_count > 0);

	mutex_lock(&ubi->buf_mutex);
	for (i = 0; i < patt_count; i++) {
		err = do_sync_erase(ubi, pnum);
		if (err)
			goto out;

		/* Make sure the PEB contains only 0xFF bytes */
		err = ubi_io_read(ubi, ubi->peb_buf1, pnum, 0, ubi->peb_size);
		if (err)
			goto out;

		err = check_pattern(ubi->peb_buf1, 0xFF, ubi->peb_size);
		if (err == 0) {
			ubi_err("erased PEB %d, but a non-0xFF byte found",
				pnum);
			err = -EIO;
			goto out;
		}

		/* Write a pattern and check it */
		memset(ubi->peb_buf1, patterns[i], ubi->peb_size);
		err = ubi_io_write(ubi, ubi->peb_buf1, pnum, 0, ubi->peb_size);
		if (err)
			goto out;

		memset(ubi->peb_buf1, ~patterns[i], ubi->peb_size);
		err = ubi_io_read(ubi, ubi->peb_buf1, pnum, 0, ubi->peb_size);
		if (err)
			goto out;

		err = check_pattern(ubi->peb_buf1, patterns[i], ubi->peb_size);
		if (err == 0) {
			ubi_err("pattern %x checking failed for PEB %d",
				patterns[i], pnum);
			err = -EIO;
			goto out;
		}
	}

	err = patt_count;

out:
	mutex_unlock(&ubi->buf_mutex);
	if (err == UBI_IO_BITFLIPS || err == -EBADMSG) {
		/*
		 * If a bit-flip or data integrity error was detected, the test
		 * has not passed because it happened on a freshly erased
		 * physical eraseblock which means something is wrong with it.
		 */
		ubi_err("read problems on freshly erased PEB %d, must be bad",
			pnum);
		err = -EIO;
	}
	return err;
}

/**
 * ubi_io_sync_erase - synchronously erase a physical eraseblock.
 * @ubi: UBI device description object
 * @pnum: physical eraseblock number to erase
 * @torture: if this physical eraseblock has to be tortured
 *
 * This function synchronously erases physical eraseblock @pnum. If @torture
 * flag is not zero, the physical eraseblock is checked by means of writing
 * different patterns to it and reading them back. If the torturing is enabled,
 * the physical eraseblock is erased more then once.
 *
 * This function returns the number of erasures made in case of success, %-EIO
 * if the erasure failed or the torturing test failed, and other negative error
 * codes in case of other errors. Note, %-EIO means that the physical
 * eraseblock is bad.
 */
int ubi_io_sync_erase(struct ubi_device *ubi, int pnum, int torture)
{
	int err, ret = 0;

	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);

	err = paranoid_check_not_bad(ubi, pnum);
	if (err != 0)
		return err > 0 ? -EINVAL : err;

	if (ubi->ro_mode) {
		ubi_err("read-only mode");
		return -EROFS;
	}

	if (torture) {
		ret = torture_peb(ubi, pnum);
		if (ret < 0)
			return ret;
	}

	err = do_sync_erase(ubi, pnum);
	if (err)
		return err;

	return ret + 1;
}

/**
 * ubi_io_is_bad - check if a physical eraseblock is bad.
 * @ubi: UBI device description object
 * @pnum: the physical eraseblock number to check
 *
 * This function returns a positive number if the physical eraseblock is bad,
 * zero if not, and a negative error code if an error occurred.
 */
int ubi_io_is_bad(const struct ubi_device *ubi, int pnum)
{
	struct mtd_info *mtd = ubi->mtd;

	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);

	if (ubi->bad_allowed) {
		int ret;

		ret = mtd->block_isbad(mtd, (loff_t)pnum * ubi->peb_size);
		if (ret < 0)
			ubi_err("error %d while checking if PEB %d is bad",
				ret, pnum);
		else if (ret)
			dbg_io("PEB %d is bad", pnum);
		return ret;
	}

	return 0;
}

/**
 * ubi_io_mark_bad - mark a physical eraseblock as bad.
 * @ubi: UBI device description object
 * @pnum: the physical eraseblock number to mark
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
int ubi_io_mark_bad(const struct ubi_device *ubi, int pnum)
{
	int err;
	struct mtd_info *mtd = ubi->mtd;

	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);

	if (ubi->ro_mode) {
		ubi_err("read-only mode");
		return -EROFS;
	}

	if (!ubi->bad_allowed)
		return 0;

	err = mtd->block_markbad(mtd, (loff_t)pnum * ubi->peb_size);
	if (err)
		ubi_err("cannot mark PEB %d bad, error %d", pnum, err);
	return err;
}

/**
 * validate_ec_hdr - validate an erase counter header.
 * @ubi: UBI device description object
 * @ec_hdr: the erase counter header to check
 *
 * This function returns zero if the erase counter header is OK, and %1 if
 * not.
 */
static int validate_ec_hdr(const struct ubi_device *ubi,
			   const struct ubi_ec_hdr *ec_hdr)
{
	long long ec;
	int vid_hdr_offset, leb_start;

	ec = be64_to_cpu(ec_hdr->ec);
	vid_hdr_offset = be32_to_cpu(ec_hdr->vid_hdr_offset);
	leb_start = be32_to_cpu(ec_hdr->data_offset);

	if (ec_hdr->version != UBI_VERSION) {
		ubi_err("node with incompatible UBI version found: "
			"this UBI version is %d, image version is %d",
			UBI_VERSION, (int)ec_hdr->version);
		goto bad;
	}

	if (vid_hdr_offset != ubi->vid_hdr_offset) {
		ubi_err("bad VID header offset %d, expected %d",
			vid_hdr_offset, ubi->vid_hdr_offset);
		goto bad;
	}

	if (leb_start != ubi->leb_start) {
		ubi_err("bad data offset %d, expected %d",
			leb_start, ubi->leb_start);
		goto bad;
	}

	if (ec < 0 || ec > UBI_MAX_ERASECOUNTER) {
		ubi_err("bad erase counter %lld", ec);
		goto bad;
	}

	return 0;

bad:
	ubi_err("bad EC header");
	ubi_dbg_dump_ec_hdr(ec_hdr);
	ubi_dbg_dump_stack();
	return 1;
}

/**
 * ubi_io_read_ec_hdr - read and check an erase counter header.
 * @ubi: UBI device description object
 * @pnum: physical eraseblock to read from
 * @ec_hdr: a &struct ubi_ec_hdr object where to store the read erase counter
 * header
 * @verbose: be verbose if the header is corrupted or was not found
 *
 * This function reads erase counter header from physical eraseblock @pnum and
 * stores it in @ec_hdr. This function also checks CRC checksum of the read
 * erase counter header. The following codes may be returned:
 *
 * o %0 if the CRC checksum is correct and the header was successfully read;
 * o %UBI_IO_BITFLIPS if the CRC is correct, but bit-flips were detected
 *   and corrected by the flash driver; this is harmless but may indicate that
 *   this eraseblock may become bad soon (but may be not);
 * o %UBI_IO_BAD_EC_HDR if the erase counter header is corrupted (a CRC error);
 * o %UBI_IO_PEB_EMPTY if the physical eraseblock is empty;
 * o a negative error code in case of failure.
 */
int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
		       struct ubi_ec_hdr *ec_hdr, int verbose)
{
	int err, read_err = 0;
	uint32_t crc, magic, hdr_crc;

	dbg_io("read EC header from PEB %d", pnum);
	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
	if (UBI_IO_DEBUG)
		verbose = 1;

	err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
	if (err) {
		if (err != UBI_IO_BITFLIPS && err != -EBADMSG)
			return err;

		/*
		 * We read all the data, but either a correctable bit-flip
		 * occurred, or MTD reported about some data integrity error,
		 * like an ECC error in case of NAND. The former is harmless,
		 * the later may mean that the read data is corrupted. But we
		 * have a CRC check-sum and we will detect this. If the EC
		 * header is still OK, we just report this as there was a
		 * bit-flip.
		 */
		read_err = err;
	}

	magic = be32_to_cpu(ec_hdr->magic);
	if (magic != UBI_EC_HDR_MAGIC) {
		/*
		 * The magic field is wrong. Let's check if we have read all
		 * 0xFF. If yes, this physical eraseblock is assumed to be
		 * empty.
		 *
		 * But if there was a read error, we do not test it for all
		 * 0xFFs. Even if it does contain all 0xFFs, this error
		 * indicates that something is still wrong with this physical
		 * eraseblock and we anyway cannot treat it as empty.
		 */
		if (read_err != -EBADMSG &&
		    check_pattern(ec_hdr, 0xFF, UBI_EC_HDR_SIZE)) {
			/* The physical eraseblock is supposedly empty */

			/*
			 * The below is just a paranoid check, it has to be
			 * compiled out if paranoid checks are disabled.
			 */
			err = paranoid_check_all_ff(ubi, pnum, 0,
						    ubi->peb_size);
			if (err)
				return err > 0 ? UBI_IO_BAD_EC_HDR : err;

			if (verbose)
				ubi_warn("no EC header found at PEB %d, "
					 "only 0xFF bytes", pnum);
			return UBI_IO_PEB_EMPTY;
		}

		/*
		 * This is not a valid erase counter header, and these are not
		 * 0xFF bytes. Report that the header is corrupted.
		 */
		if (verbose) {
			ubi_warn("bad magic number at PEB %d: %08x instead of "
				 "%08x", pnum, magic, UBI_EC_HDR_MAGIC);
			ubi_dbg_dump_ec_hdr(ec_hdr);
		}
		return UBI_IO_BAD_EC_HDR;
	}

	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
	hdr_crc = be32_to_cpu(ec_hdr->hdr_crc);

	if (hdr_crc != crc) {
		if (verbose) {
			ubi_warn("bad EC header CRC at PEB %d, calculated %#08x,"
				 " read %#08x", pnum, crc, hdr_crc);
			ubi_dbg_dump_ec_hdr(ec_hdr);
		}
		return UBI_IO_BAD_EC_HDR;
	}

	/* And of course validate what has just been read from the media */
	err = validate_ec_hdr(ubi, ec_hdr);
	if (err) {
		ubi_err("validation failed for PEB %d", pnum);
		return -EINVAL;
	}

	return read_err ? UBI_IO_BITFLIPS : 0;
}

/**
 * ubi_io_write_ec_hdr - write an erase counter header.
 * @ubi: UBI device description object
 * @pnum: physical eraseblock to write to
 * @ec_hdr: the erase counter header to write
 *
 * This function writes erase counter header described by @ec_hdr to physical
 * eraseblock @pnum. It also fills most fields of @ec_hdr before writing, so
 * the caller do not have to fill them. Callers must only fill the @ec_hdr->ec
 * field.
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure. If %-EIO is returned, the physical eraseblock most probably
 * went bad.
 */
int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,
			struct ubi_ec_hdr *ec_hdr)
{
	int err;
	uint32_t crc;

	dbg_io("write EC header to PEB %d", pnum);
	ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);

	ec_hdr->magic = cpu_to_be32(UBI_EC_HDR_MAGIC);
	ec_hdr->version = UBI_VERSION;
	ec_hdr->vid_hdr_offset = cpu_to_be32(ubi->vid_hdr_offset);
	ec_hdr->data_offset = cpu_to_be32(ubi->leb_start);
	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
	ec_hdr->hdr_crc = cpu_to_be32(crc);

	err = paranoid_check_ec_hdr(ubi, pnum, ec_hdr);
	if (err)
		return -EINVAL;

	err = ubi_io_write(ubi, ec_hdr, pnum, 0, ubi->ec_hdr_alsize);
	return err;
}

/**
 * validate_vid_hdr - validate a volume identifier header.
 * @ubi: UBI device description object
 * @vid_hdr: the volume identifier header to check
 *
 * This function checks that data stored in the volume identifier header
 * @vid_hdr. Returns zero if the VID header is OK and %1 if not.
 */
static int validate_vid_hdr(const struct ubi_device *ubi,
			    const struct ubi_vid_hdr *vid_hdr)
{
	int vol_type = vid_hdr->vol_type;
	int copy_flag = vid_hdr->copy_flag;
	int vol_id = be32_to_cpu(vid_hdr->vol_id);
	int lnum = be32_to_cpu(vid_hdr->lnum);
	int compat = vid_hdr->compat;
	int data_size = be32_to_cpu(vid_hdr->data_size);
	int used_ebs = be32_to_cpu(vid_hdr->used_ebs);
	int data_pad = be32_to_cpu(vid_hdr->data_pad);
	int data_crc = be32_to_cpu(vid_hdr->data_crc);
	int usable_leb_size = ubi->leb_size - data_pad;

	if (copy_flag != 0 && copy_flag != 1) {
		dbg_err("bad copy_flag");
		goto bad;
	}

	if (vol_id < 0 || lnum < 0 || data_size < 0 || used_ebs < 0 ||
	    data_pad < 0) {
		dbg_err("negative values");
		goto bad;
	}

	if (vol_id >= UBI_MAX_VOLUMES && vol_id < UBI_INTERNAL_VOL_START) {
		dbg_err("bad vol_id");
		goto bad;
	}

	if (vol_id < UBI_INTERNAL_VOL_START && compat != 0) {
		dbg_err("bad compat");
		goto bad;
	}

	if (vol_id >= UBI_INTERNAL_VOL_START && compat != UBI_COMPAT_DELETE &&
	    compat != UBI_COMPAT_RO && compat != UBI_COMPAT_PRESERVE &&
	    compat != UBI_COMPAT_REJECT) {
		dbg_err("bad compat");
		goto bad;
	}

	if (vol_type != UBI_VID_DYNAMIC && vol_type != UBI_VID_STATIC) {
		dbg_err("bad vol_type");
		goto bad;
	}

	if (data_pad >= ubi->leb_size / 2) {
		dbg_err("bad data_pad");
		goto bad;
	}

	if (vol_type == UBI_VID_STATIC) {
		/*
		 * Although from high-level point of view static volumes may
		 * contain zero bytes of data, but no VID headers can contain
		 * zero at these fields, because they empty volumes do not have
		 * mapped logical eraseblocks.
		 */
		if (used_ebs == 0) {
			dbg_err("zero used_ebs");
			goto bad;
		}
		if (data_size == 0) {
			dbg_err("zero data_size");
			goto bad;
		}
		if (lnum < used_ebs - 1) {
			if (data_size != usable_leb_size) {
				dbg_err("bad data_size");
				goto bad;
			}
		} else if (lnum == used_ebs - 1) {
			if (data_size == 0) {
				dbg_err("bad data_size at last LEB");
				goto bad;
			}
		} else {
			dbg_err("too high lnum");
			goto bad;
		}
	} else {
		if (copy_flag == 0) {
			if (data_crc != 0) {
				dbg_err("non-zero data CRC");
				goto bad;
			}
			if (data_size != 0) {
				dbg_err("non-zero data_size");
				goto bad;
			}
		} else {
			if (data_size == 0) {
				dbg_err("zero data_size of copy");
				goto bad;
			}
		}
		if (used_ebs != 0) {
			dbg_err("bad used_ebs");
			goto bad;
		}
	}

	return 0;

bad:
	ubi_err("bad VID header");
	ubi_dbg_dump_vid_hdr(vid_hdr);
	ubi_dbg_dump_stack();
	return 1;
}

/**
 * ubi_io_read_vid_hdr - read and check a volume identifier header.
 * @ubi: UBI device description object
 * @pnum: physical eraseblock number to read from
 * @vid_hdr: &struct ubi_vid_hdr object where to store the read volume
 * identifier header
 * @verbose: be verbose if the header is corrupted or wasn't found
 *
 * This function reads the volume identifier header from physical eraseblock
 * @pnum and stores it in @vid_hdr. It also checks CRC checksum of the read
 * volume identifier header. The following codes may be returned:
 *
 * o %0 if the CRC checksum is correct and the header was successfully read;
 * o %UBI_IO_BITFLIPS if the CRC is correct, but bit-flips were detected
 *   and corrected by the flash driver; this is harmless but may indicate that
 *   this eraseblock may become bad soon;
 * o %UBI_IO_BAD_VID_HRD if the volume identifier header is corrupted (a CRC
 *   error detected);
 * o %UBI_IO_PEB_FREE if the physical eraseblock is free (i.e., there is no VID
 *   header there);
 * o a negative error code in case of failure.
 */
int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
			struct ubi_vid_hdr *vid_hdr, int verbose)
{
	int err, read_err = 0;
	uint32_t crc, magic, hdr_crc;
	void *p;

	dbg_io("read VID header from PEB %d", pnum);
	ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
	if (UBI_IO_DEBUG)
		verbose = 1;

	p = (char *)vid_hdr - ubi->vid_hdr_shift;
	err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
			  ubi->vid_hdr_alsize);
	if (err) {
		if (err != UBI_IO_BITFLIPS && err != -EBADMSG)
			return err;

		/*
		 * We read all the data, but either a correctable bit-flip
		 * occurred, or MTD reported about some data integrity error,
		 * like an ECC error in case of NAND. The former is harmless,
		 * the later may mean the read data is corrupted. But we have a
		 * CRC check-sum and we will identify this. If the VID header is
		 * still OK, we just report this as there was a bit-flip.
		 */
		read_err = err;
	}

	magic = be32_to_cpu(vid_hdr->magic);
	if (magic != UBI_VID_HDR_MAGIC) {
		/*
		 * If we have read all 0xFF bytes, the VID header probably does
		 * not exist and the physical eraseblock is assumed to be free.
		 *
		 * But if there was a read error, we do not test the data for
		 * 0xFFs. Even if it does contain all 0xFFs, this error
		 * indicates that something is still wrong with this physical
		 * eraseblock and it cannot be regarded as free.
		 */
		if (read_err != -EBADMSG &&
		    check_pattern(vid_hdr, 0xFF, UBI_VID_HDR_SIZE)) {
			/* The physical eraseblock is supposedly free */

			/*
			 * The below is just a paranoid check, it has to be
			 * compiled out if paranoid checks are disabled.
			 */
			err = paranoid_check_all_ff(ubi, pnum, ubi->leb_start,
						    ubi->leb_size);
			if (err)
				return err > 0 ? UBI_IO_BAD_VID_HDR : err;

			if (verbose)
				ubi_warn("no VID header found at PEB %d, "
					 "only 0xFF bytes", pnum);
			return UBI_IO_PEB_FREE;
		}

		/*
		 * This is not a valid VID header, and these are not 0xFF
		 * bytes. Report that the header is corrupted.
		 */
		if (verbose) {
			ubi_warn("bad magic number at PEB %d: %08x instead of "
				 "%08x", pnum, magic, UBI_VID_HDR_MAGIC);
			ubi_dbg_dump_vid_hdr(vid_hdr);
		}
		return UBI_IO_BAD_VID_HDR;
	}

	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
	hdr_crc = be32_to_cpu(vid_hdr->hdr_crc);

	if (hdr_crc != crc) {
		if (verbose) {
			ubi_warn("bad CRC at PEB %d, calculated %#08x, "
				 "read %#08x", pnum, crc, hdr_crc);
			ubi_dbg_dump_vid_hdr(vid_hdr);
		}
		return UBI_IO_BAD_VID_HDR;
	}

	/* Validate the VID header that we have just read */
	err = validate_vid_hdr(ubi, vid_hdr);
	if (err) {
		ubi_err("validation failed for PEB %d", pnum);
		return -EINVAL;
	}

	return read_err ? UBI_IO_BITFLIPS : 0;
}

/**
 * ubi_io_write_vid_hdr - write a volume identifier header.
 * @ubi: UBI device description object
 * @pnum: the physical eraseblock number to write to
 * @vid_hdr: the volume identifier header to write
 *
 * This function writes the volume identifier header described by @vid_hdr to
 * physical eraseblock @pnum. This function automatically fills the
 * @vid_hdr->magic and the @vid_hdr->version fields, as well as calculates
 * header CRC checksum and stores it at vid_hdr->hdr_crc.
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure. If %-EIO is returned, the physical eraseblock probably went
 * bad.
 */
int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
			 struct ubi_vid_hdr *vid_hdr)
{
	int err;
	uint32_t crc;
	void *p;

	dbg_io("write VID header to PEB %d", pnum);
	ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);

	err = paranoid_check_peb_ec_hdr(ubi, pnum);
	if (err)
		return err > 0 ? -EINVAL: err;

	vid_hdr->magic = cpu_to_be32(UBI_VID_HDR_MAGIC);
	vid_hdr->version = UBI_VERSION;
	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
	vid_hdr->hdr_crc = cpu_to_be32(crc);

	err = paranoid_check_vid_hdr(ubi, pnum, vid_hdr);
	if (err)
		return -EINVAL;

	p = (char *)vid_hdr - ubi->vid_hdr_shift;
	err = ubi_io_write(ubi, p, pnum, ubi->vid_hdr_aloffset,
			   ubi->vid_hdr_alsize);
	return err;
}

#ifdef CONFIG_MTD_UBI_DEBUG_PARANOID

/**
 * paranoid_check_not_bad - ensure that a physical eraseblock is not bad.
 * @ubi: UBI device description object
 * @pnum: physical eraseblock number to check
 *
 * This function returns zero if the physical eraseblock is good, a positive
 * number if it is bad and a negative error code if an error occurred.
 */
static int paranoid_check_not_bad(const struct ubi_device *ubi, int pnum)
{
	int err;

	err = ubi_io_is_bad(ubi, pnum);
	if (!err)
		return err;

	ubi_err("paranoid check failed for PEB %d", pnum);
	ubi_dbg_dump_stack();
	return err;
}

/**
 * paranoid_check_ec_hdr - check if an erase counter header is all right.
 * @ubi: UBI device description object
 * @pnum: physical eraseblock number the erase counter header belongs to
 * @ec_hdr: the erase counter header to check
 *
 * This function returns zero if the erase counter header contains valid
 * values, and %1 if not.
 */
static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
				 const struct ubi_ec_hdr *ec_hdr)
{
	int err;
	uint32_t magic;

	magic = be32_to_cpu(ec_hdr->magic);
	if (magic != UBI_EC_HDR_MAGIC) {
		ubi_err("bad magic %#08x, must be %#08x",
			magic, UBI_EC_HDR_MAGIC);
		goto fail;
	}

	err = validate_ec_hdr(ubi, ec_hdr);
	if (err) {
		ubi_err("paranoid check failed for PEB %d", pnum);
		goto fail;
	}

	return 0;

fail:
	ubi_dbg_dump_ec_hdr(ec_hdr);
	ubi_dbg_dump_stack();
	return 1;
}

/**
 * paranoid_check_peb_ec_hdr - check that the erase counter header of a
 * physical eraseblock is in-place and is all right.
 * @ubi: UBI device description object
 * @pnum: the physical eraseblock number to check
 *
 * This function returns zero if the erase counter header is all right, %1 if
 * not, and a negative error code if an error occurred.
 */
static int paranoid_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum)
{
	int err;
	uint32_t crc, hdr_crc;
	struct ubi_ec_hdr *ec_hdr;

	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
	if (!ec_hdr)
		return -ENOMEM;

	err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
	if (err && err != UBI_IO_BITFLIPS && err != -EBADMSG)
		goto exit;

	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
	hdr_crc = be32_to_cpu(ec_hdr->hdr_crc);
	if (hdr_crc != crc) {
		ubi_err("bad CRC, calculated %#08x, read %#08x", crc, hdr_crc);
		ubi_err("paranoid check failed for PEB %d", pnum);
		ubi_dbg_dump_ec_hdr(ec_hdr);
		ubi_dbg_dump_stack();
		err = 1;
		goto exit;
	}

	err = paranoid_check_ec_hdr(ubi, pnum, ec_hdr);

exit:
	kfree(ec_hdr);
	return err;
}

/**
 * paranoid_check_vid_hdr - check that a volume identifier header is all right.
 * @ubi: UBI device description object
 * @pnum: physical eraseblock number the volume identifier header belongs to
 * @vid_hdr: the volume identifier header to check
 *
 * This function returns zero if the volume identifier header is all right, and
 * %1 if not.
 */
static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
				  const struct ubi_vid_hdr *vid_hdr)
{
	int err;
	uint32_t magic;

	magic = be32_to_cpu(vid_hdr->magic);
	if (magic != UBI_VID_HDR_MAGIC) {
		ubi_err("bad VID header magic %#08x at PEB %d, must be %#08x",
			magic, pnum, UBI_VID_HDR_MAGIC);
		goto fail;
	}

	err = validate_vid_hdr(ubi, vid_hdr);
	if (err) {
		ubi_err("paranoid check failed for PEB %d", pnum);
		goto fail;
	}

	return err;

fail:
	ubi_err("paranoid check failed for PEB %d", pnum);
	ubi_dbg_dump_vid_hdr(vid_hdr);
	ubi_dbg_dump_stack();
	return 1;

}

/**
 * paranoid_check_peb_vid_hdr - check that the volume identifier header of a
 * physical eraseblock is in-place and is all right.
 * @ubi: UBI device description object
 * @pnum: the physical eraseblock number to check
 *
 * This function returns zero if the volume identifier header is all right,
 * %1 if not, and a negative error code if an error occurred.
 */
static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum)
{
	int err;
	uint32_t crc, hdr_crc;
	struct ubi_vid_hdr *vid_hdr;
	void *p;

	vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
	if (!vid_hdr)
		return -ENOMEM;

	p = (char *)vid_hdr - ubi->vid_hdr_shift;
	err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
			  ubi->vid_hdr_alsize);
	if (err && err != UBI_IO_BITFLIPS && err != -EBADMSG)
		goto exit;

	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_EC_HDR_SIZE_CRC);
	hdr_crc = be32_to_cpu(vid_hdr->hdr_crc);
	if (hdr_crc != crc) {
		ubi_err("bad VID header CRC at PEB %d, calculated %#08x, "
			"read %#08x", pnum, crc, hdr_crc);
		ubi_err("paranoid check failed for PEB %d", pnum);
		ubi_dbg_dump_vid_hdr(vid_hdr);
		ubi_dbg_dump_stack();
		err = 1;
		goto exit;
	}

	err = paranoid_check_vid_hdr(ubi, pnum, vid_hdr);

exit:
	ubi_free_vid_hdr(ubi, vid_hdr);
	return err;
}

/**
 * paranoid_check_all_ff - check that a region of flash is empty.
 * @ubi: UBI device description object
 * @pnum: the physical eraseblock number to check
 * @offset: the starting offset within the physical eraseblock to check
 * @len: the length of the region to check
 *
 * This function returns zero if only 0xFF bytes are present at offset
 * @offset of the physical eraseblock @pnum, %1 if not, and a negative error
 * code if an error occurred.
 */
static int paranoid_check_all_ff(struct ubi_device *ubi, int pnum, int offset,
				 int len)
{
	size_t read;
	int err;
	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;

	mutex_lock(&ubi->dbg_buf_mutex);
	err = ubi->mtd->read(ubi->mtd, addr, len, &read, ubi->dbg_peb_buf);
	if (err && err != -EUCLEAN) {
		ubi_err("error %d while reading %d bytes from PEB %d:%d, "
			"read %zd bytes", err, len, pnum, offset, read);
		goto error;
	}

	err = check_pattern(ubi->dbg_peb_buf, 0xFF, len);
	if (err == 0) {
		ubi_err("flash region at PEB %d:%d, length %d does not "
			"contain all 0xFF bytes", pnum, offset, len);
		goto fail;
	}
	mutex_unlock(&ubi->dbg_buf_mutex);

	return 0;

fail:
	ubi_err("paranoid check failed for PEB %d", pnum);
	dbg_msg("hex dump of the %d-%d region", offset, offset + len);
	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
		       ubi->dbg_peb_buf, len, 1);
	err = 1;
error:
	ubi_dbg_dump_stack();
	mutex_unlock(&ubi->dbg_buf_mutex);
	return err;
}

#endif /* CONFIG_MTD_UBI_DEBUG_PARANOID */