summaryrefslogtreecommitdiffstats
path: root/drivers/mtd/ubi/build.c
blob: fb59604854c9fb4f0438458d764a92b249c6fdb7 (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
/*
 * Copyright (c) International Business Machines Corp., 2006
 * Copyright (c) Nokia Corporation, 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),
 *         Frank Haverkamp
 */

/*
 * This file includes UBI initialization and building of UBI devices.
 *
 * When UBI is initialized, it attaches all the MTD devices specified as the
 * module load parameters or the kernel boot parameters. If MTD devices were
 * specified, UBI does not attach any MTD device, but it is possible to do
 * later using the "UBI control device".
 */

#include <linux/err.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/stringify.h>
#include <linux/namei.h>
#include <linux/stat.h>
#include <linux/miscdevice.h>
#include <linux/mtd/partitions.h>
#include <linux/log2.h>
#include <linux/kthread.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include "ubi.h"

/* Maximum length of the 'mtd=' parameter */
#define MTD_PARAM_LEN_MAX 64

/* Maximum number of comma-separated items in the 'mtd=' parameter */
#define MTD_PARAM_MAX_COUNT 3

/* Maximum value for the number of bad PEBs per 1024 PEBs */
#define MAX_MTD_UBI_BEB_LIMIT 768

#ifdef CONFIG_MTD_UBI_MODULE
#define ubi_is_module() 1
#else
#define ubi_is_module() 0
#endif

/**
 * struct mtd_dev_param - MTD device parameter description data structure.
 * @name: MTD character device node path, MTD device name, or MTD device number
 *        string
 * @vid_hdr_offs: VID header offset
 * @max_beb_per1024: maximum expected number of bad PEBs per 1024 PEBs
 */
struct mtd_dev_param {
	char name[MTD_PARAM_LEN_MAX];
	int vid_hdr_offs;
	int max_beb_per1024;
};

/* Numbers of elements set in the @mtd_dev_param array */
static int __initdata mtd_devs;

/* MTD devices specification parameters */
static struct mtd_dev_param __initdata mtd_dev_param[UBI_MAX_DEVICES];
#ifdef CONFIG_MTD_UBI_FASTMAP
/* UBI module parameter to enable fastmap automatically on non-fastmap images */
static bool fm_autoconvert;
#endif
/* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
struct class *ubi_class;

/* Slab cache for wear-leveling entries */
struct kmem_cache *ubi_wl_entry_slab;

/* UBI control character device */
static struct miscdevice ubi_ctrl_cdev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "ubi_ctrl",
	.fops = &ubi_ctrl_cdev_operations,
};

/* All UBI devices in system */
static struct ubi_device *ubi_devices[UBI_MAX_DEVICES];

/* Serializes UBI devices creations and removals */
DEFINE_MUTEX(ubi_devices_mutex);

/* Protects @ubi_devices and @ubi->ref_count */
static DEFINE_SPINLOCK(ubi_devices_lock);

/* "Show" method for files in '/<sysfs>/class/ubi/' */
static ssize_t ubi_version_show(struct class *class,
				struct class_attribute *attr, char *buf)
{
	return sprintf(buf, "%d\n", UBI_VERSION);
}

/* UBI version attribute ('/<sysfs>/class/ubi/version') */
static struct class_attribute ubi_version =
	__ATTR(version, S_IRUGO, ubi_version_show, NULL);

static ssize_t dev_attribute_show(struct device *dev,
				  struct device_attribute *attr, char *buf);

/* UBI device attributes (correspond to files in '/<sysfs>/class/ubi/ubiX') */
static struct device_attribute dev_eraseblock_size =
	__ATTR(eraseblock_size, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_avail_eraseblocks =
	__ATTR(avail_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_total_eraseblocks =
	__ATTR(total_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_volumes_count =
	__ATTR(volumes_count, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_max_ec =
	__ATTR(max_ec, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_reserved_for_bad =
	__ATTR(reserved_for_bad, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_bad_peb_count =
	__ATTR(bad_peb_count, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_max_vol_count =
	__ATTR(max_vol_count, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_min_io_size =
	__ATTR(min_io_size, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_bgt_enabled =
	__ATTR(bgt_enabled, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_mtd_num =
	__ATTR(mtd_num, S_IRUGO, dev_attribute_show, NULL);

/**
 * ubi_volume_notify - send a volume change notification.
 * @ubi: UBI device description object
 * @vol: volume description object of the changed volume
 * @ntype: notification type to send (%UBI_VOLUME_ADDED, etc)
 *
 * This is a helper function which notifies all subscribers about a volume
 * change event (creation, removal, re-sizing, re-naming, updating). Returns
 * zero in case of success and a negative error code in case of failure.
 */
int ubi_volume_notify(struct ubi_device *ubi, struct ubi_volume *vol, int ntype)
{
	struct ubi_notification nt;

	ubi_do_get_device_info(ubi, &nt.di);
	ubi_do_get_volume_info(ubi, vol, &nt.vi);

#ifdef CONFIG_MTD_UBI_FASTMAP
	switch (ntype) {
	case UBI_VOLUME_ADDED:
	case UBI_VOLUME_REMOVED:
	case UBI_VOLUME_RESIZED:
	case UBI_VOLUME_RENAMED:
		if (ubi_update_fastmap(ubi)) {
			ubi_err("Unable to update fastmap!");
			ubi_ro_mode(ubi);
		}
	}
#endif
	return blocking_notifier_call_chain(&ubi_notifiers, ntype, &nt);
}

/**
 * ubi_notify_all - send a notification to all volumes.
 * @ubi: UBI device description object
 * @ntype: notification type to send (%UBI_VOLUME_ADDED, etc)
 * @nb: the notifier to call
 *
 * This function walks all volumes of UBI device @ubi and sends the @ntype
 * notification for each volume. If @nb is %NULL, then all registered notifiers
 * are called, otherwise only the @nb notifier is called. Returns the number of
 * sent notifications.
 */
int ubi_notify_all(struct ubi_device *ubi, int ntype, struct notifier_block *nb)
{
	struct ubi_notification nt;
	int i, count = 0;

	ubi_do_get_device_info(ubi, &nt.di);

	mutex_lock(&ubi->device_mutex);
	for (i = 0; i < ubi->vtbl_slots; i++) {
		/*
		 * Since the @ubi->device is locked, and we are not going to
		 * change @ubi->volumes, we do not have to lock
		 * @ubi->volumes_lock.
		 */
		if (!ubi->volumes[i])
			continue;

		ubi_do_get_volume_info(ubi, ubi->volumes[i], &nt.vi);
		if (nb)
			nb->notifier_call(nb, ntype, &nt);
		else
			blocking_notifier_call_chain(&ubi_notifiers, ntype,
						     &nt);
		count += 1;
	}
	mutex_unlock(&ubi->device_mutex);

	return count;
}

/**
 * ubi_enumerate_volumes - send "add" notification for all existing volumes.
 * @nb: the notifier to call
 *
 * This function walks all UBI devices and volumes and sends the
 * %UBI_VOLUME_ADDED notification for each volume. If @nb is %NULL, then all
 * registered notifiers are called, otherwise only the @nb notifier is called.
 * Returns the number of sent notifications.
 */
int ubi_enumerate_volumes(struct notifier_block *nb)
{
	int i, count = 0;

	/*
	 * Since the @ubi_devices_mutex is locked, and we are not going to
	 * change @ubi_devices, we do not have to lock @ubi_devices_lock.
	 */
	for (i = 0; i < UBI_MAX_DEVICES; i++) {
		struct ubi_device *ubi = ubi_devices[i];

		if (!ubi)
			continue;
		count += ubi_notify_all(ubi, UBI_VOLUME_ADDED, nb);
	}

	return count;
}

/**
 * ubi_get_device - get UBI device.
 * @ubi_num: UBI device number
 *
 * This function returns UBI device description object for UBI device number
 * @ubi_num, or %NULL if the device does not exist. This function increases the
 * device reference count to prevent removal of the device. In other words, the
 * device cannot be removed if its reference count is not zero.
 */
struct ubi_device *ubi_get_device(int ubi_num)
{
	struct ubi_device *ubi;

	spin_lock(&ubi_devices_lock);
	ubi = ubi_devices[ubi_num];
	if (ubi) {
		ubi_assert(ubi->ref_count >= 0);
		ubi->ref_count += 1;
		get_device(&ubi->dev);
	}
	spin_unlock(&ubi_devices_lock);

	return ubi;
}

/**
 * ubi_put_device - drop an UBI device reference.
 * @ubi: UBI device description object
 */
void ubi_put_device(struct ubi_device *ubi)
{
	spin_lock(&ubi_devices_lock);
	ubi->ref_count -= 1;
	put_device(&ubi->dev);
	spin_unlock(&ubi_devices_lock);
}

/**
 * ubi_get_by_major - get UBI device by character device major number.
 * @major: major number
 *
 * This function is similar to 'ubi_get_device()', but it searches the device
 * by its major number.
 */
struct ubi_device *ubi_get_by_major(int major)
{
	int i;
	struct ubi_device *ubi;

	spin_lock(&ubi_devices_lock);
	for (i = 0; i < UBI_MAX_DEVICES; i++) {
		ubi = ubi_devices[i];
		if (ubi && MAJOR(ubi->cdev.dev) == major) {
			ubi_assert(ubi->ref_count >= 0);
			ubi->ref_count += 1;
			get_device(&ubi->dev);
			spin_unlock(&ubi_devices_lock);
			return ubi;
		}
	}
	spin_unlock(&ubi_devices_lock);

	return NULL;
}

/**
 * ubi_major2num - get UBI device number by character device major number.
 * @major: major number
 *
 * This function searches UBI device number object by its major number. If UBI
 * device was not found, this function returns -ENODEV, otherwise the UBI device
 * number is returned.
 */
int ubi_major2num(int major)
{
	int i, ubi_num = -ENODEV;

	spin_lock(&ubi_devices_lock);
	for (i = 0; i < UBI_MAX_DEVICES; i++) {
		struct ubi_device *ubi = ubi_devices[i];

		if (ubi && MAJOR(ubi->cdev.dev) == major) {
			ubi_num = ubi->ubi_num;
			break;
		}
	}
	spin_unlock(&ubi_devices_lock);

	return ubi_num;
}

/* "Show" method for files in '/<sysfs>/class/ubi/ubiX/' */
static ssize_t dev_attribute_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	ssize_t ret;
	struct ubi_device *ubi;

	/*
	 * The below code looks weird, but it actually makes sense. We get the
	 * UBI device reference from the contained 'struct ubi_device'. But it
	 * is unclear if the device was removed or not yet. Indeed, if the
	 * device was removed before we increased its reference count,
	 * 'ubi_get_device()' will return -ENODEV and we fail.
	 *
	 * Remember, 'struct ubi_device' is freed in the release function, so
	 * we still can use 'ubi->ubi_num'.
	 */
	ubi = container_of(dev, struct ubi_device, dev);
	ubi = ubi_get_device(ubi->ubi_num);
	if (!ubi)
		return -ENODEV;

	if (attr == &dev_eraseblock_size)
		ret = sprintf(buf, "%d\n", ubi->leb_size);
	else if (attr == &dev_avail_eraseblocks)
		ret = sprintf(buf, "%d\n", ubi->avail_pebs);
	else if (attr == &dev_total_eraseblocks)
		ret = sprintf(buf, "%d\n", ubi->good_peb_count);
	else if (attr == &dev_volumes_count)
		ret = sprintf(buf, "%d\n", ubi->vol_count - UBI_INT_VOL_COUNT);
	else if (attr == &dev_max_ec)
		ret = sprintf(buf, "%d\n", ubi->max_ec);
	else if (attr == &dev_reserved_for_bad)
		ret = sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
	else if (attr == &dev_bad_peb_count)
		ret = sprintf(buf, "%d\n", ubi->bad_peb_count);
	else if (attr == &dev_max_vol_count)
		ret = sprintf(buf, "%d\n", ubi->vtbl_slots);
	else if (attr == &dev_min_io_size)
		ret = sprintf(buf, "%d\n", ubi->min_io_size);
	else if (attr == &dev_bgt_enabled)
		ret = sprintf(buf, "%d\n", ubi->thread_enabled);
	else if (attr == &dev_mtd_num)
		ret = sprintf(buf, "%d\n", ubi->mtd->index);
	else
		ret = -EINVAL;

	ubi_put_device(ubi);
	return ret;
}

static void dev_release(struct device *dev)
{
	struct ubi_device *ubi = container_of(dev, struct ubi_device, dev);

	kfree(ubi);
}

/**
 * ubi_sysfs_init - initialize sysfs for an UBI device.
 * @ubi: UBI device description object
 * @ref: set to %1 on exit in case of failure if a reference to @ubi->dev was
 *       taken
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int ubi_sysfs_init(struct ubi_device *ubi, int *ref)
{
	int err;

	ubi->dev.release = dev_release;
	ubi->dev.devt = ubi->cdev.dev;
	ubi->dev.class = ubi_class;
	dev_set_name(&ubi->dev, UBI_NAME_STR"%d", ubi->ubi_num);
	err = device_register(&ubi->dev);
	if (err)
		return err;

	*ref = 1;
	err = device_create_file(&ubi->dev, &dev_eraseblock_size);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_avail_eraseblocks);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_total_eraseblocks);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_volumes_count);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_max_ec);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_reserved_for_bad);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_bad_peb_count);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_max_vol_count);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_min_io_size);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_bgt_enabled);
	if (err)
		return err;
	err = device_create_file(&ubi->dev, &dev_mtd_num);
	return err;
}

/**
 * ubi_sysfs_close - close sysfs for an UBI device.
 * @ubi: UBI device description object
 */
static void ubi_sysfs_close(struct ubi_device *ubi)
{
	device_remove_file(&ubi->dev, &dev_mtd_num);
	device_remove_file(&ubi->dev, &dev_bgt_enabled);
	device_remove_file(&ubi->dev, &dev_min_io_size);
	device_remove_file(&ubi->dev, &dev_max_vol_count);
	device_remove_file(&ubi->dev, &dev_bad_peb_count);
	device_remove_file(&ubi->dev, &dev_reserved_for_bad);
	device_remove_file(&ubi->dev, &dev_max_ec);
	device_remove_file(&ubi->dev, &dev_volumes_count);
	device_remove_file(&ubi->dev, &dev_total_eraseblocks);
	device_remove_file(&ubi->dev, &dev_avail_eraseblocks);
	device_remove_file(&ubi->dev, &dev_eraseblock_size);
	device_unregister(&ubi->dev);
}

/**
 * kill_volumes - destroy all user volumes.
 * @ubi: UBI device description object
 */
static void kill_volumes(struct ubi_device *ubi)
{
	int i;

	for (i = 0; i < ubi->vtbl_slots; i++)
		if (ubi->volumes[i])
			ubi_free_volume(ubi, ubi->volumes[i]);
}

/**
 * uif_init - initialize user interfaces for an UBI device.
 * @ubi: UBI device description object
 * @ref: set to %1 on exit in case of failure if a reference to @ubi->dev was
 *       taken, otherwise set to %0
 *
 * This function initializes various user interfaces for an UBI device. If the
 * initialization fails at an early stage, this function frees all the
 * resources it allocated, returns an error, and @ref is set to %0. However,
 * if the initialization fails after the UBI device was registered in the
 * driver core subsystem, this function takes a reference to @ubi->dev, because
 * otherwise the release function ('dev_release()') would free whole @ubi
 * object. The @ref argument is set to %1 in this case. The caller has to put
 * this reference.
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int uif_init(struct ubi_device *ubi, int *ref)
{
	int i, err;
	dev_t dev;

	*ref = 0;
	sprintf(ubi->ubi_name, UBI_NAME_STR "%d", ubi->ubi_num);

	/*
	 * Major numbers for the UBI character devices are allocated
	 * dynamically. Major numbers of volume character devices are
	 * equivalent to ones of the corresponding UBI character device. Minor
	 * numbers of UBI character devices are 0, while minor numbers of
	 * volume character devices start from 1. Thus, we allocate one major
	 * number and ubi->vtbl_slots + 1 minor numbers.
	 */
	err = alloc_chrdev_region(&dev, 0, ubi->vtbl_slots + 1, ubi->ubi_name);
	if (err) {
		ubi_err("cannot register UBI character devices");
		return err;
	}

	ubi_assert(MINOR(dev) == 0);
	cdev_init(&ubi->cdev, &ubi_cdev_operations);
	dbg_gen("%s major is %u", ubi->ubi_name, MAJOR(dev));
	ubi->cdev.owner = THIS_MODULE;

	err = cdev_add(&ubi->cdev, dev, 1);
	if (err) {
		ubi_err("cannot add character device");
		goto out_unreg;
	}

	err = ubi_sysfs_init(ubi, ref);
	if (err)
		goto out_sysfs;

	for (i = 0; i < ubi->vtbl_slots; i++)
		if (ubi->volumes[i]) {
			err = ubi_add_volume(ubi, ubi->volumes[i]);
			if (err) {
				ubi_err("cannot add volume %d", i);
				goto out_volumes;
			}
		}

	return 0;

out_volumes:
	kill_volumes(ubi);
out_sysfs:
	if (*ref)
		get_device(&ubi->dev);
	ubi_sysfs_close(ubi);
	cdev_del(&ubi->cdev);
out_unreg:
	unregister_chrdev_region(ubi->cdev.dev, ubi->vtbl_slots + 1);
	ubi_err("cannot initialize UBI %s, error %d", ubi->ubi_name, err);
	return err;
}

/**
 * uif_close - close user interfaces for an UBI device.
 * @ubi: UBI device description object
 *
 * Note, since this function un-registers UBI volume device objects (@vol->dev),
 * the memory allocated voe the volumes is freed as well (in the release
 * function).
 */
static void uif_close(struct ubi_device *ubi)
{
	kill_volumes(ubi);
	ubi_sysfs_close(ubi);
	cdev_del(&ubi->cdev);
	unregister_chrdev_region(ubi->cdev.dev, ubi->vtbl_slots + 1);
}

/**
 * ubi_free_internal_volumes - free internal volumes.
 * @ubi: UBI device description object
 */
void ubi_free_internal_volumes(struct ubi_device *ubi)
{
	int i;

	for (i = ubi->vtbl_slots;
	     i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
		kfree(ubi->volumes[i]->eba_tbl);
		kfree(ubi->volumes[i]);
	}
}

static int get_bad_peb_limit(const struct ubi_device *ubi, int max_beb_per1024)
{
	int limit, device_pebs;
	uint64_t device_size;

	if (!max_beb_per1024)
		return 0;

	/*
	 * Here we are using size of the entire flash chip and
	 * not just the MTD partition size because the maximum
	 * number of bad eraseblocks is a percentage of the
	 * whole device and bad eraseblocks are not fairly
	 * distributed over the flash chip. So the worst case
	 * is that all the bad eraseblocks of the chip are in
	 * the MTD partition we are attaching (ubi->mtd).
	 */
	device_size = mtd_get_device_size(ubi->mtd);
	device_pebs = mtd_div_by_eb(device_size, ubi->mtd);
	limit = mult_frac(device_pebs, max_beb_per1024, 1024);

	/* Round it up */
	if (mult_frac(limit, 1024, max_beb_per1024) < device_pebs)
		limit += 1;

	return limit;
}

/**
 * io_init - initialize I/O sub-system for a given UBI device.
 * @ubi: UBI device description object
 * @max_beb_per1024: maximum expected number of bad PEB per 1024 PEBs
 *
 * If @ubi->vid_hdr_offset or @ubi->leb_start is zero, default offsets are
 * assumed:
 *   o EC header is always at offset zero - this cannot be changed;
 *   o VID header starts just after the EC header at the closest address
 *     aligned to @io->hdrs_min_io_size;
 *   o data starts just after the VID header at the closest address aligned to
 *     @io->min_io_size
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int io_init(struct ubi_device *ubi, int max_beb_per1024)
{
	dbg_gen("sizeof(struct ubi_ainf_peb) %zu", sizeof(struct ubi_ainf_peb));
	dbg_gen("sizeof(struct ubi_wl_entry) %zu", sizeof(struct ubi_wl_entry));

	if (ubi->mtd->numeraseregions != 0) {
		/*
		 * Some flashes have several erase regions. Different regions
		 * may have different eraseblock size and other
		 * characteristics. It looks like mostly multi-region flashes
		 * have one "main" region and one or more small regions to
		 * store boot loader code or boot parameters or whatever. I
		 * guess we should just pick the largest region. But this is
		 * not implemented.
		 */
		ubi_err("multiple regions, not implemented");
		return -EINVAL;
	}

	if (ubi->vid_hdr_offset < 0)
		return -EINVAL;

	/*
	 * Note, in this implementation we support MTD devices with 0x7FFFFFFF
	 * physical eraseblocks maximum.
	 */

	ubi->peb_size   = ubi->mtd->erasesize;
	ubi->peb_count  = mtd_div_by_eb(ubi->mtd->size, ubi->mtd);
	ubi->flash_size = ubi->mtd->size;

	if (mtd_can_have_bb(ubi->mtd)) {
		ubi->bad_allowed = 1;
		ubi->bad_peb_limit = get_bad_peb_limit(ubi, max_beb_per1024);
	}

	if (ubi->mtd->type == MTD_NORFLASH) {
		ubi_assert(ubi->mtd->writesize == 1);
		ubi->nor_flash = 1;
	}

	ubi->min_io_size = ubi->mtd->writesize;
	ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft;

	/*
	 * Make sure minimal I/O unit is power of 2. Note, there is no
	 * fundamental reason for this assumption. It is just an optimization
	 * which allows us to avoid costly division operations.
	 */
	if (!is_power_of_2(ubi->min_io_size)) {
		ubi_err("min. I/O unit (%d) is not power of 2",
			ubi->min_io_size);
		return -EINVAL;
	}

	ubi_assert(ubi->hdrs_min_io_size > 0);
	ubi_assert(ubi->hdrs_min_io_size <= ubi->min_io_size);
	ubi_assert(ubi->min_io_size % ubi->hdrs_min_io_size == 0);

	ubi->max_write_size = ubi->mtd->writebufsize;
	/*
	 * Maximum write size has to be greater or equivalent to min. I/O
	 * size, and be multiple of min. I/O size.
	 */
	if (ubi->max_write_size < ubi->min_io_size ||
	    ubi->max_write_size % ubi->min_io_size ||
	    !is_power_of_2(ubi->max_write_size)) {
		ubi_err("bad write buffer size %d for %d min. I/O unit",
			ubi->max_write_size, ubi->min_io_size);
		return -EINVAL;
	}

	/* Calculate default aligned sizes of EC and VID headers */
	ubi->ec_hdr_alsize = ALIGN(UBI_EC_HDR_SIZE, ubi->hdrs_min_io_size);
	ubi->vid_hdr_alsize = ALIGN(UBI_VID_HDR_SIZE, ubi->hdrs_min_io_size);

	dbg_gen("min_io_size      %d", ubi->min_io_size);
	dbg_gen("max_write_size   %d", ubi->max_write_size);
	dbg_gen("hdrs_min_io_size %d", ubi->hdrs_min_io_size);
	dbg_gen("ec_hdr_alsize    %d", ubi->ec_hdr_alsize);
	dbg_gen("vid_hdr_alsize   %d", ubi->vid_hdr_alsize);

	if (ubi->vid_hdr_offset == 0)
		/* Default offset */
		ubi->vid_hdr_offset = ubi->vid_hdr_aloffset =
				      ubi->ec_hdr_alsize;
	else {
		ubi->vid_hdr_aloffset = ubi->vid_hdr_offset &
						~(ubi->hdrs_min_io_size - 1);
		ubi->vid_hdr_shift = ubi->vid_hdr_offset -
						ubi->vid_hdr_aloffset;
	}

	/* Similar for the data offset */
	ubi->leb_start = ubi->vid_hdr_offset + UBI_VID_HDR_SIZE;
	ubi->leb_start = ALIGN(ubi->leb_start, ubi->min_io_size);

	dbg_gen("vid_hdr_offset   %d", ubi->vid_hdr_offset);
	dbg_gen("vid_hdr_aloffset %d", ubi->vid_hdr_aloffset);
	dbg_gen("vid_hdr_shift    %d", ubi->vid_hdr_shift);
	dbg_gen("leb_start        %d", ubi->leb_start);

	/* The shift must be aligned to 32-bit boundary */
	if (ubi->vid_hdr_shift % 4) {
		ubi_err("unaligned VID header shift %d",
			ubi->vid_hdr_shift);
		return -EINVAL;
	}

	/* Check sanity */
	if (ubi->vid_hdr_offset < UBI_EC_HDR_SIZE ||
	    ubi->leb_start < ubi->vid_hdr_offset + UBI_VID_HDR_SIZE ||
	    ubi->leb_start > ubi->peb_size - UBI_VID_HDR_SIZE ||
	    ubi->leb_start & (ubi->min_io_size - 1)) {
		ubi_err("bad VID header (%d) or data offsets (%d)",
			ubi->vid_hdr_offset, ubi->leb_start);
		return -EINVAL;
	}

	/*
	 * Set maximum amount of physical erroneous eraseblocks to be 10%.
	 * Erroneous PEB are those which have read errors.
	 */
	ubi->max_erroneous = ubi->peb_count / 10;
	if (ubi->max_erroneous < 16)
		ubi->max_erroneous = 16;
	dbg_gen("max_erroneous    %d", ubi->max_erroneous);

	/*
	 * It may happen that EC and VID headers are situated in one minimal
	 * I/O unit. In this case we can only accept this UBI image in
	 * read-only mode.
	 */
	if (ubi->vid_hdr_offset + UBI_VID_HDR_SIZE <= ubi->hdrs_min_io_size) {
		ubi_warn("EC and VID headers are in the same minimal I/O unit, switch to read-only mode");
		ubi->ro_mode = 1;
	}

	ubi->leb_size = ubi->peb_size - ubi->leb_start;

	if (!(ubi->mtd->flags & MTD_WRITEABLE)) {
		ubi_msg("MTD device %d is write-protected, attach in read-only mode",
			ubi->mtd->index);
		ubi->ro_mode = 1;
	}

	/*
	 * Note, ideally, we have to initialize @ubi->bad_peb_count here. But
	 * unfortunately, MTD does not provide this information. We should loop
	 * over all physical eraseblocks and invoke mtd->block_is_bad() for
	 * each physical eraseblock. So, we leave @ubi->bad_peb_count
	 * uninitialized so far.
	 */

	return 0;
}

/**
 * autoresize - re-size the volume which has the "auto-resize" flag set.
 * @ubi: UBI device description object
 * @vol_id: ID of the volume to re-size
 *
 * This function re-sizes the volume marked by the %UBI_VTBL_AUTORESIZE_FLG in
 * the volume table to the largest possible size. See comments in ubi-header.h
 * for more description of the flag. Returns zero in case of success and a
 * negative error code in case of failure.
 */
static int autoresize(struct ubi_device *ubi, int vol_id)
{
	struct ubi_volume_desc desc;
	struct ubi_volume *vol = ubi->volumes[vol_id];
	int err, old_reserved_pebs = vol->reserved_pebs;

	if (ubi->ro_mode) {
		ubi_warn("skip auto-resize because of R/O mode");
		return 0;
	}

	/*
	 * Clear the auto-resize flag in the volume in-memory copy of the
	 * volume table, and 'ubi_resize_volume()' will propagate this change
	 * to the flash.
	 */
	ubi->vtbl[vol_id].flags &= ~UBI_VTBL_AUTORESIZE_FLG;

	if (ubi->avail_pebs == 0) {
		struct ubi_vtbl_record vtbl_rec;

		/*
		 * No available PEBs to re-size the volume, clear the flag on
		 * flash and exit.
		 */
		vtbl_rec = ubi->vtbl[vol_id];
		err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
		if (err)
			ubi_err("cannot clean auto-resize flag for volume %d",
				vol_id);
	} else {
		desc.vol = vol;
		err = ubi_resize_volume(&desc,
					old_reserved_pebs + ubi->avail_pebs);
		if (err)
			ubi_err("cannot auto-resize volume %d", vol_id);
	}

	if (err)
		return err;

	ubi_msg("volume %d (\"%s\") re-sized from %d to %d LEBs", vol_id,
		vol->name, old_reserved_pebs, vol->reserved_pebs);
	return 0;
}

/**
 * ubi_attach_mtd_dev - attach an MTD device.
 * @mtd: MTD device description object
 * @ubi_num: number to assign to the new UBI device
 * @vid_hdr_offset: VID header offset
 * @max_beb_per1024: maximum expected number of bad PEB per 1024 PEBs
 *
 * This function attaches MTD device @mtd_dev to UBI and assign @ubi_num number
 * to the newly created UBI device, unless @ubi_num is %UBI_DEV_NUM_AUTO, in
 * which case this function finds a vacant device number and assigns it
 * automatically. Returns the new UBI device number in case of success and a
 * negative error code in case of failure.
 *
 * Note, the invocations of this function has to be serialized by the
 * @ubi_devices_mutex.
 */
int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
		       int vid_hdr_offset, int max_beb_per1024)
{
	struct ubi_device *ubi;
	int i, err, ref = 0;

	if (max_beb_per1024 < 0 || max_beb_per1024 > MAX_MTD_UBI_BEB_LIMIT)
		return -EINVAL;

	if (!max_beb_per1024)
		max_beb_per1024 = CONFIG_MTD_UBI_BEB_LIMIT;

	/*
	 * Check if we already have the same MTD device attached.
	 *
	 * Note, this function assumes that UBI devices creations and deletions
	 * are serialized, so it does not take the &ubi_devices_lock.
	 */
	for (i = 0; i < UBI_MAX_DEVICES; i++) {
		ubi = ubi_devices[i];
		if (ubi && mtd->index == ubi->mtd->index) {
			ubi_err("mtd%d is already attached to ubi%d",
				mtd->index, i);
			return -EEXIST;
		}
	}

	/*
	 * Make sure this MTD device is not emulated on top of an UBI volume
	 * already. Well, generally this recursion works fine, but there are
	 * different problems like the UBI module takes a reference to itself
	 * by attaching (and thus, opening) the emulated MTD device. This
	 * results in inability to unload the module. And in general it makes
	 * no sense to attach emulated MTD devices, so we prohibit this.
	 */
	if (mtd->type == MTD_UBIVOLUME) {
		ubi_err("refuse attaching mtd%d - it is already emulated on top of UBI",
			mtd->index);
		return -EINVAL;
	}

	if (ubi_num == UBI_DEV_NUM_AUTO) {
		/* Search for an empty slot in the @ubi_devices array */
		for (ubi_num = 0; ubi_num < UBI_MAX_DEVICES; ubi_num++)
			if (!ubi_devices[ubi_num])
				break;
		if (ubi_num == UBI_MAX_DEVICES) {
			ubi_err("only %d UBI devices may be created",
				UBI_MAX_DEVICES);
			return -ENFILE;
		}
	} else {
		if (ubi_num >= UBI_MAX_DEVICES)
			return -EINVAL;

		/* Make sure ubi_num is not busy */
		if (ubi_devices[ubi_num]) {
			ubi_err("ubi%d already exists", ubi_num);
			return -EEXIST;
		}
	}

	ubi = kzalloc(sizeof(struct ubi_device), GFP_KERNEL);
	if (!ubi)
		return -ENOMEM;

	ubi->mtd = mtd;
	ubi->ubi_num = ubi_num;
	ubi->vid_hdr_offset = vid_hdr_offset;
	ubi->autoresize_vol_id = -1;

#ifdef CONFIG_MTD_UBI_FASTMAP
	ubi->fm_pool.used = ubi->fm_pool.size = 0;
	ubi->fm_wl_pool.used = ubi->fm_wl_pool.size = 0;

	/*
	 * fm_pool.max_size is 5% of the total number of PEBs but it's also
	 * between UBI_FM_MAX_POOL_SIZE and UBI_FM_MIN_POOL_SIZE.
	 */
	ubi->fm_pool.max_size = min(((int)mtd_div_by_eb(ubi->mtd->size,
		ubi->mtd) / 100) * 5, UBI_FM_MAX_POOL_SIZE);
	if (ubi->fm_pool.max_size < UBI_FM_MIN_POOL_SIZE)
		ubi->fm_pool.max_size = UBI_FM_MIN_POOL_SIZE;

	ubi->fm_wl_pool.max_size = UBI_FM_WL_POOL_SIZE;
	ubi->fm_disabled = !fm_autoconvert;

	if (!ubi->fm_disabled && (int)mtd_div_by_eb(ubi->mtd->size, ubi->mtd)
	    <= UBI_FM_MAX_START) {
		ubi_err("More than %i PEBs are needed for fastmap, sorry.",
			UBI_FM_MAX_START);
		ubi->fm_disabled = 1;
	}

	ubi_msg("default fastmap pool size: %d", ubi->fm_pool.max_size);
	ubi_msg("default fastmap WL pool size: %d", ubi->fm_wl_pool.max_size);
#else
	ubi->fm_disabled = 1;
#endif
	mutex_init(&ubi->buf_mutex);
	mutex_init(&ubi->ckvol_mutex);
	mutex_init(&ubi->device_mutex);
	spin_lock_init(&ubi->volumes_lock);
	mutex_init(&ubi->fm_mutex);
	init_rwsem(&ubi->fm_sem);

	ubi_msg("attaching mtd%d to ubi%d", mtd->index, ubi_num);

	err = io_init(ubi, max_beb_per1024);
	if (err)
		goto out_free;

	err = -ENOMEM;
	ubi->peb_buf = vmalloc(ubi->peb_size);
	if (!ubi->peb_buf)
		goto out_free;

#ifdef CONFIG_MTD_UBI_FASTMAP
	ubi->fm_size = ubi_calc_fm_size(ubi);
	ubi->fm_buf = vzalloc(ubi->fm_size);
	if (!ubi->fm_buf)
		goto out_free;
#endif
	err = ubi_debugging_init_dev(ubi);
	if (err)
		goto out_free;

	err = ubi_attach(ubi, 0);
	if (err) {
		ubi_err("failed to attach mtd%d, error %d", mtd->index, err);
		goto out_debugging;
	}

	if (ubi->autoresize_vol_id != -1) {
		err = autoresize(ubi, ubi->autoresize_vol_id);
		if (err)
			goto out_detach;
	}

	err = uif_init(ubi, &ref);
	if (err)
		goto out_detach;

	err = ubi_debugfs_init_dev(ubi);
	if (err)
		goto out_uif;

	ubi->bgt_thread = kthread_create(ubi_thread, ubi, ubi->bgt_name);
	if (IS_ERR(ubi->bgt_thread)) {
		err = PTR_ERR(ubi->bgt_thread);
		ubi_err("cannot spawn \"%s\", error %d", ubi->bgt_name,
			err);
		goto out_debugfs;
	}

	ubi_msg("attached mtd%d (name \"%s\", size %llu MiB) to ubi%d",
		mtd->index, mtd->name, ubi->flash_size >> 20, ubi_num);
	ubi_msg("PEB size: %d bytes (%d KiB), LEB size: %d bytes",
		ubi->peb_size, ubi->peb_size >> 10, ubi->leb_size);
	ubi_msg("min./max. I/O unit sizes: %d/%d, sub-page size %d",
		ubi->min_io_size, ubi->max_write_size, ubi->hdrs_min_io_size);
	ubi_msg("VID header offset: %d (aligned %d), data offset: %d",
		ubi->vid_hdr_offset, ubi->vid_hdr_aloffset, ubi->leb_start);
	ubi_msg("good PEBs: %d, bad PEBs: %d, corrupted PEBs: %d",
		ubi->good_peb_count, ubi->bad_peb_count, ubi->corr_peb_count);
	ubi_msg("user volume: %d, internal volumes: %d, max. volumes count: %d",
		ubi->vol_count - UBI_INT_VOL_COUNT, UBI_INT_VOL_COUNT,
		ubi->vtbl_slots);
	ubi_msg("max/mean erase counter: %d/%d, WL threshold: %d, image sequence number: %u",
		ubi->max_ec, ubi->mean_ec, CONFIG_MTD_UBI_WL_THRESHOLD,
		ubi->image_seq);
	ubi_msg("available PEBs: %d, total reserved PEBs: %d, PEBs reserved for bad PEB handling: %d",
		ubi->avail_pebs, ubi->rsvd_pebs, ubi->beb_rsvd_pebs);

	/*
	 * The below lock makes sure we do not race with 'ubi_thread()' which
	 * checks @ubi->thread_enabled. Otherwise we may fail to wake it up.
	 */
	spin_lock(&ubi->wl_lock);
	ubi->thread_enabled = 1;
	wake_up_process(ubi->bgt_thread);
	spin_unlock(&ubi->wl_lock);

	ubi_devices[ubi_num] = ubi;
	ubi_notify_all(ubi, UBI_VOLUME_ADDED, NULL);
	return ubi_num;

out_debugfs:
	ubi_debugfs_exit_dev(ubi);
out_uif:
	get_device(&ubi->dev);
	ubi_assert(ref);
	uif_close(ubi);
out_detach:
	ubi_wl_close(ubi);
	ubi_free_internal_volumes(ubi);
	vfree(ubi->vtbl);
out_debugging:
	ubi_debugging_exit_dev(ubi);
out_free:
	vfree(ubi->peb_buf);
	vfree(ubi->fm_buf);
	if (ref)
		put_device(&ubi->dev);
	else
		kfree(ubi);
	return err;
}

/**
 * ubi_detach_mtd_dev - detach an MTD device.
 * @ubi_num: UBI device number to detach from
 * @anyway: detach MTD even if device reference count is not zero
 *
 * This function destroys an UBI device number @ubi_num and detaches the
 * underlying MTD device. Returns zero in case of success and %-EBUSY if the
 * UBI device is busy and cannot be destroyed, and %-EINVAL if it does not
 * exist.
 *
 * Note, the invocations of this function has to be serialized by the
 * @ubi_devices_mutex.
 */
int ubi_detach_mtd_dev(int ubi_num, int anyway)
{
	struct ubi_device *ubi;

	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
		return -EINVAL;

	ubi = ubi_get_device(ubi_num);
	if (!ubi)
		return -EINVAL;

	spin_lock(&ubi_devices_lock);
	put_device(&ubi->dev);
	ubi->ref_count -= 1;
	if (ubi->ref_count) {
		if (!anyway) {
			spin_unlock(&ubi_devices_lock);
			return -EBUSY;
		}
		/* This may only happen if there is a bug */
		ubi_err("%s reference count %d, destroy anyway",
			ubi->ubi_name, ubi->ref_count);
	}
	ubi_devices[ubi_num] = NULL;
	spin_unlock(&ubi_devices_lock);

	ubi_assert(ubi_num == ubi->ubi_num);
	ubi_notify_all(ubi, UBI_VOLUME_REMOVED, NULL);
	ubi_msg("detaching mtd%d from ubi%d", ubi->mtd->index, ubi_num);
#ifdef CONFIG_MTD_UBI_FASTMAP
	/* If we don't write a new fastmap at detach time we lose all
	 * EC updates that have been made since the last written fastmap. */
	ubi_update_fastmap(ubi);
#endif
	/*
	 * Before freeing anything, we have to stop the background thread to
	 * prevent it from doing anything on this device while we are freeing.
	 */
	if (ubi->bgt_thread)
		kthread_stop(ubi->bgt_thread);

	/*
	 * Get a reference to the device in order to prevent 'dev_release()'
	 * from freeing the @ubi object.
	 */
	get_device(&ubi->dev);

	ubi_debugfs_exit_dev(ubi);
	uif_close(ubi);

	ubi_wl_close(ubi);
	ubi_free_internal_volumes(ubi);
	vfree(ubi->vtbl);
	put_mtd_device(ubi->mtd);
	ubi_debugging_exit_dev(ubi);
	vfree(ubi->peb_buf);
	vfree(ubi->fm_buf);
	ubi_msg("mtd%d is detached from ubi%d", ubi->mtd->index, ubi->ubi_num);
	put_device(&ubi->dev);
	return 0;
}

/**
 * open_mtd_by_chdev - open an MTD device by its character device node path.
 * @mtd_dev: MTD character device node path
 *
 * This helper function opens an MTD device by its character node device path.
 * Returns MTD device description object in case of success and a negative
 * error code in case of failure.
 */
static struct mtd_info * __init open_mtd_by_chdev(const char *mtd_dev)
{
	int err, major, minor, mode;
	struct path path;

	/* Probably this is an MTD character device node path */
	err = kern_path(mtd_dev, LOOKUP_FOLLOW, &path);
	if (err)
		return ERR_PTR(err);

	/* MTD device number is defined by the major / minor numbers */
	major = imajor(path.dentry->d_inode);
	minor = iminor(path.dentry->d_inode);
	mode = path.dentry->d_inode->i_mode;
	path_put(&path);
	if (major != MTD_CHAR_MAJOR || !S_ISCHR(mode))
		return ERR_PTR(-EINVAL);

	if (minor & 1)
		/*
		 * Just do not think the "/dev/mtdrX" devices support is need,
		 * so do not support them to avoid doing extra work.
		 */
		return ERR_PTR(-EINVAL);

	return get_mtd_device(NULL, minor / 2);
}

/**
 * open_mtd_device - open MTD device by name, character device path, or number.
 * @mtd_dev: name, character device node path, or MTD device device number
 *
 * This function tries to open and MTD device described by @mtd_dev string,
 * which is first treated as ASCII MTD device number, and if it is not true, it
 * is treated as MTD device name, and if that is also not true, it is treated
 * as MTD character device node path. Returns MTD device description object in
 * case of success and a negative error code in case of failure.
 */
static struct mtd_info * __init open_mtd_device(const char *mtd_dev)
{
	struct mtd_info *mtd;
	int mtd_num;
	char *endp;

	mtd_num = simple_strtoul(mtd_dev, &endp, 0);
	if (*endp != '\0' || mtd_dev == endp) {
		/*
		 * This does not look like an ASCII integer, probably this is
		 * MTD device name.
		 */
		mtd = get_mtd_device_nm(mtd_dev);
		if (IS_ERR(mtd) && PTR_ERR(mtd) == -ENODEV)
			/* Probably this is an MTD character device node path */
			mtd = open_mtd_by_chdev(mtd_dev);
	} else
		mtd = get_mtd_device(NULL, mtd_num);

	return mtd;
}

static int __init ubi_init(void)
{
	int err, i, k;

	/* Ensure that EC and VID headers have correct size */
	BUILD_BUG_ON(sizeof(struct ubi_ec_hdr) != 64);
	BUILD_BUG_ON(sizeof(struct ubi_vid_hdr) != 64);

	if (mtd_devs > UBI_MAX_DEVICES) {
		ubi_err("too many MTD devices, maximum is %d", UBI_MAX_DEVICES);
		return -EINVAL;
	}

	/* Create base sysfs directory and sysfs files */
	ubi_class = class_create(THIS_MODULE, UBI_NAME_STR);
	if (IS_ERR(ubi_class)) {
		err = PTR_ERR(ubi_class);
		ubi_err("cannot create UBI class");
		goto out;
	}

	err = class_create_file(ubi_class, &ubi_version);
	if (err) {
		ubi_err("cannot create sysfs file");
		goto out_class;
	}

	err = misc_register(&ubi_ctrl_cdev);
	if (err) {
		ubi_err("cannot register device");
		goto out_version;
	}

	ubi_wl_entry_slab = kmem_cache_create("ubi_wl_entry_slab",
					      sizeof(struct ubi_wl_entry),
					      0, 0, NULL);
	if (!ubi_wl_entry_slab)
		goto out_dev_unreg;

	err = ubi_debugfs_init();
	if (err)
		goto out_slab;


	/* Attach MTD devices */
	for (i = 0; i < mtd_devs; i++) {
		struct mtd_dev_param *p = &mtd_dev_param[i];
		struct mtd_info *mtd;

		cond_resched();

		mtd = open_mtd_device(p->name);
		if (IS_ERR(mtd)) {
			err = PTR_ERR(mtd);
			goto out_detach;
		}

		mutex_lock(&ubi_devices_mutex);
		err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO,
					 p->vid_hdr_offs, p->max_beb_per1024);
		mutex_unlock(&ubi_devices_mutex);
		if (err < 0) {
			ubi_err("cannot attach mtd%d", mtd->index);
			put_mtd_device(mtd);

			/*
			 * Originally UBI stopped initializing on any error.
			 * However, later on it was found out that this
			 * behavior is not very good when UBI is compiled into
			 * the kernel and the MTD devices to attach are passed
			 * through the command line. Indeed, UBI failure
			 * stopped whole boot sequence.
			 *
			 * To fix this, we changed the behavior for the
			 * non-module case, but preserved the old behavior for
			 * the module case, just for compatibility. This is a
			 * little inconsistent, though.
			 */
			if (ubi_is_module())
				goto out_detach;
		}
	}

	return 0;

out_detach:
	for (k = 0; k < i; k++)
		if (ubi_devices[k]) {
			mutex_lock(&ubi_devices_mutex);
			ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1);
			mutex_unlock(&ubi_devices_mutex);
		}
	ubi_debugfs_exit();
out_slab:
	kmem_cache_destroy(ubi_wl_entry_slab);
out_dev_unreg:
	misc_deregister(&ubi_ctrl_cdev);
out_version:
	class_remove_file(ubi_class, &ubi_version);
out_class:
	class_destroy(ubi_class);
out:
	ubi_err("UBI error: cannot initialize UBI, error %d", err);
	return err;
}
late_initcall(ubi_init);

static void __exit ubi_exit(void)
{
	int i;

	for (i = 0; i < UBI_MAX_DEVICES; i++)
		if (ubi_devices[i]) {
			mutex_lock(&ubi_devices_mutex);
			ubi_detach_mtd_dev(ubi_devices[i]->ubi_num, 1);
			mutex_unlock(&ubi_devices_mutex);
		}
	ubi_debugfs_exit();
	kmem_cache_destroy(ubi_wl_entry_slab);
	misc_deregister(&ubi_ctrl_cdev);
	class_remove_file(ubi_class, &ubi_version);
	class_destroy(ubi_class);
}
module_exit(ubi_exit);

/**
 * bytes_str_to_int - convert a number of bytes string into an integer.
 * @str: the string to convert
 *
 * This function returns positive resulting integer in case of success and a
 * negative error code in case of failure.
 */
static int __init bytes_str_to_int(const char *str)
{
	char *endp;
	unsigned long result;

	result = simple_strtoul(str, &endp, 0);
	if (str == endp || result >= INT_MAX) {
		ubi_err("UBI error: incorrect bytes count: \"%s\"\n", str);
		return -EINVAL;
	}

	switch (*endp) {
	case 'G':
		result *= 1024;
	case 'M':
		result *= 1024;
	case 'K':
		result *= 1024;
		if (endp[1] == 'i' && endp[2] == 'B')
			endp += 2;
	case '\0':
		break;
	default:
		ubi_err("UBI error: incorrect bytes count: \"%s\"\n", str);
		return -EINVAL;
	}

	return result;
}

/**
 * ubi_mtd_param_parse - parse the 'mtd=' UBI parameter.
 * @val: the parameter value to parse
 * @kp: not used
 *
 * This function returns zero in case of success and a negative error code in
 * case of error.
 */
static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
{
	int i, len;
	struct mtd_dev_param *p;
	char buf[MTD_PARAM_LEN_MAX];
	char *pbuf = &buf[0];
	char *tokens[MTD_PARAM_MAX_COUNT];

	if (!val)
		return -EINVAL;

	if (mtd_devs == UBI_MAX_DEVICES) {
		ubi_err("UBI error: too many parameters, max. is %d\n",
			UBI_MAX_DEVICES);
		return -EINVAL;
	}

	len = strnlen(val, MTD_PARAM_LEN_MAX);
	if (len == MTD_PARAM_LEN_MAX) {
		ubi_err("UBI error: parameter \"%s\" is too long, max. is %d\n",
			val, MTD_PARAM_LEN_MAX);
		return -EINVAL;
	}

	if (len == 0) {
		pr_warn("UBI warning: empty 'mtd=' parameter - ignored\n");
		return 0;
	}

	strcpy(buf, val);

	/* Get rid of the final newline */
	if (buf[len - 1] == '\n')
		buf[len - 1] = '\0';

	for (i = 0; i < MTD_PARAM_MAX_COUNT; i++)
		tokens[i] = strsep(&pbuf, ",");

	if (pbuf) {
		ubi_err("UBI error: too many arguments at \"%s\"\n", val);
		return -EINVAL;
	}

	p = &mtd_dev_param[mtd_devs];
	strcpy(&p->name[0], tokens[0]);

	if (tokens[1])
		p->vid_hdr_offs = bytes_str_to_int(tokens[1]);

	if (p->vid_hdr_offs < 0)
		return p->vid_hdr_offs;

	if (tokens[2]) {
		int err = kstrtoint(tokens[2], 10, &p->max_beb_per1024);

		if (err) {
			ubi_err("UBI error: bad value for max_beb_per1024 parameter: %s",
				tokens[2]);
			return -EINVAL;
		}
	}

	mtd_devs += 1;
	return 0;
}

module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000);
MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: mtd=<name|num|path>[,<vid_hdr_offs>[,max_beb_per1024]].\n"
		      "Multiple \"mtd\" parameters may be specified.\n"
		      "MTD devices may be specified by their number, name, or path to the MTD character device node.\n"
		      "Optional \"vid_hdr_offs\" parameter specifies UBI VID header position to be used by UBI. (default value if 0)\n"
		      "Optional \"max_beb_per1024\" parameter specifies the maximum expected bad eraseblock per 1024 eraseblocks. (default value ("
		      __stringify(CONFIG_MTD_UBI_BEB_LIMIT) ") if 0)\n"
		      "\n"
		      "Example 1: mtd=/dev/mtd0 - attach MTD device /dev/mtd0.\n"
		      "Example 2: mtd=content,1984 mtd=4 - attach MTD device with name \"content\" using VID header offset 1984, and MTD device number 4 with default VID header offset.\n"
		      "Example 3: mtd=/dev/mtd1,0,25 - attach MTD device /dev/mtd1 using default VID header offset and reserve 25*nand_size_in_blocks/1024 erase blocks for bad block handling.\n"
		      "\t(e.g. if the NAND *chipset* has 4096 PEB, 100 will be reserved for this UBI device).");
#ifdef CONFIG_MTD_UBI_FASTMAP
module_param(fm_autoconvert, bool, 0644);
MODULE_PARM_DESC(fm_autoconvert, "Set this parameter to enable fastmap automatically on images without a fastmap.");
#endif
MODULE_VERSION(__stringify(UBI_VERSION));
MODULE_DESCRIPTION("UBI - Unsorted Block Images");
MODULE_AUTHOR("Artem Bityutskiy");
MODULE_LICENSE("GPL");