Linux Audio

Check our new training course

Embedded Linux Audio

Check our new training course
with Creative Commons CC-BY-SA
lecture materials

Bootlin logo

Elixir Cross Referencer

Loading...
   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
/*
 * Copyright (c) International Business Machines Corp., 2006
 *
 * 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)
 */

/*
 * The UBI Eraseblock Association (EBA) sub-system.
 *
 * This sub-system is responsible for I/O to/from logical eraseblock.
 *
 * Although in this implementation the EBA table is fully kept and managed in
 * RAM, which assumes poor scalability, it might be (partially) maintained on
 * flash in future implementations.
 *
 * The EBA sub-system implements per-logical eraseblock locking. Before
 * accessing a logical eraseblock it is locked for reading or writing. The
 * per-logical eraseblock locking is implemented by means of the lock tree. The
 * lock tree is an RB-tree which refers all the currently locked logical
 * eraseblocks. The lock tree elements are &struct ubi_ltree_entry objects.
 * They are indexed by (@vol_id, @lnum) pairs.
 *
 * EBA also maintains the global sequence counter which is incremented each
 * time a logical eraseblock is mapped to a physical eraseblock and it is
 * stored in the volume identifier header. This means that each VID header has
 * a unique sequence number. The sequence number is only increased an we assume
 * 64 bits is enough to never overflow.
 */

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

/* Number of physical eraseblocks reserved for atomic LEB change operation */
#define EBA_RESERVED_PEBS 1

/**
 * next_sqnum - get next sequence number.
 * @ubi: UBI device description object
 *
 * This function returns next sequence number to use, which is just the current
 * global sequence counter value. It also increases the global sequence
 * counter.
 */
unsigned long long ubi_next_sqnum(struct ubi_device *ubi)
{
	unsigned long long sqnum;

	spin_lock(&ubi->ltree_lock);
	sqnum = ubi->global_sqnum++;
	spin_unlock(&ubi->ltree_lock);

	return sqnum;
}

/**
 * ubi_get_compat - get compatibility flags of a volume.
 * @ubi: UBI device description object
 * @vol_id: volume ID
 *
 * This function returns compatibility flags for an internal volume. User
 * volumes have no compatibility flags, so %0 is returned.
 */
static int ubi_get_compat(const struct ubi_device *ubi, int vol_id)
{
	if (vol_id == UBI_LAYOUT_VOLUME_ID)
		return UBI_LAYOUT_VOLUME_COMPAT;
	return 0;
}

/**
 * ltree_lookup - look up the lock tree.
 * @ubi: UBI device description object
 * @vol_id: volume ID
 * @lnum: logical eraseblock number
 *
 * This function returns a pointer to the corresponding &struct ubi_ltree_entry
 * object if the logical eraseblock is locked and %NULL if it is not.
 * @ubi->ltree_lock has to be locked.
 */
static struct ubi_ltree_entry *ltree_lookup(struct ubi_device *ubi, int vol_id,
					    int lnum)
{
	struct rb_node *p;

	p = ubi->ltree.rb_node;
	while (p) {
		struct ubi_ltree_entry *le;

		le = rb_entry(p, struct ubi_ltree_entry, rb);

		if (vol_id < le->vol_id)
			p = p->rb_left;
		else if (vol_id > le->vol_id)
			p = p->rb_right;
		else {
			if (lnum < le->lnum)
				p = p->rb_left;
			else if (lnum > le->lnum)
				p = p->rb_right;
			else
				return le;
		}
	}

	return NULL;
}

/**
 * ltree_add_entry - add new entry to the lock tree.
 * @ubi: UBI device description object
 * @vol_id: volume ID
 * @lnum: logical eraseblock number
 *
 * This function adds new entry for logical eraseblock (@vol_id, @lnum) to the
 * lock tree. If such entry is already there, its usage counter is increased.
 * Returns pointer to the lock tree entry or %-ENOMEM if memory allocation
 * failed.
 */
static struct ubi_ltree_entry *ltree_add_entry(struct ubi_device *ubi,
					       int vol_id, int lnum)
{
	struct ubi_ltree_entry *le, *le1, *le_free;

	le = kmalloc(sizeof(struct ubi_ltree_entry), GFP_NOFS);
	if (!le)
		return ERR_PTR(-ENOMEM);

	le->users = 0;
	init_rwsem(&le->mutex);
	le->vol_id = vol_id;
	le->lnum = lnum;

	spin_lock(&ubi->ltree_lock);
	le1 = ltree_lookup(ubi, vol_id, lnum);

	if (le1) {
		/*
		 * This logical eraseblock is already locked. The newly
		 * allocated lock entry is not needed.
		 */
		le_free = le;
		le = le1;
	} else {
		struct rb_node **p, *parent = NULL;

		/*
		 * No lock entry, add the newly allocated one to the
		 * @ubi->ltree RB-tree.
		 */
		le_free = NULL;

		p = &ubi->ltree.rb_node;
		while (*p) {
			parent = *p;
			le1 = rb_entry(parent, struct ubi_ltree_entry, rb);

			if (vol_id < le1->vol_id)
				p = &(*p)->rb_left;
			else if (vol_id > le1->vol_id)
				p = &(*p)->rb_right;
			else {
				ubi_assert(lnum != le1->lnum);
				if (lnum < le1->lnum)
					p = &(*p)->rb_left;
				else
					p = &(*p)->rb_right;
			}
		}

		rb_link_node(&le->rb, parent, p);
		rb_insert_color(&le->rb, &ubi->ltree);
	}
	le->users += 1;
	spin_unlock(&ubi->ltree_lock);

	kfree(le_free);
	return le;
}

/**
 * leb_read_lock - lock logical eraseblock for reading.
 * @ubi: UBI device description object
 * @vol_id: volume ID
 * @lnum: logical eraseblock number
 *
 * This function locks a logical eraseblock for reading. Returns zero in case
 * of success and a negative error code in case of failure.
 */
static int leb_read_lock(struct ubi_device *ubi, int vol_id, int lnum)
{
	struct ubi_ltree_entry *le;

	le = ltree_add_entry(ubi, vol_id, lnum);
	if (IS_ERR(le))
		return PTR_ERR(le);
	down_read(&le->mutex);
	return 0;
}

/**
 * leb_read_unlock - unlock logical eraseblock.
 * @ubi: UBI device description object
 * @vol_id: volume ID
 * @lnum: logical eraseblock number
 */
static void leb_read_unlock(struct ubi_device *ubi, int vol_id, int lnum)
{
	struct ubi_ltree_entry *le;

	spin_lock(&ubi->ltree_lock);
	le = ltree_lookup(ubi, vol_id, lnum);
	le->users -= 1;
	ubi_assert(le->users >= 0);
	up_read(&le->mutex);
	if (le->users == 0) {
		rb_erase(&le->rb, &ubi->ltree);
		kfree(le);
	}
	spin_unlock(&ubi->ltree_lock);
}

/**
 * leb_write_lock - lock logical eraseblock for writing.
 * @ubi: UBI device description object
 * @vol_id: volume ID
 * @lnum: logical eraseblock number
 *
 * This function locks a logical eraseblock for writing. Returns zero in case
 * of success and a negative error code in case of failure.
 */
static int leb_write_lock(struct ubi_device *ubi, int vol_id, int lnum)
{
	struct ubi_ltree_entry *le;

	le = ltree_add_entry(ubi, vol_id, lnum);
	if (IS_ERR(le))
		return PTR_ERR(le);
	down_write(&le->mutex);
	return 0;
}

/**
 * leb_write_lock - lock logical eraseblock for writing.
 * @ubi: UBI device description object
 * @vol_id: volume ID
 * @lnum: logical eraseblock number
 *
 * This function locks a logical eraseblock for writing if there is no
 * contention and does nothing if there is contention. Returns %0 in case of
 * success, %1 in case of contention, and and a negative error code in case of
 * failure.
 */
static int leb_write_trylock(struct ubi_device *ubi, int vol_id, int lnum)
{
	struct ubi_ltree_entry *le;

	le = ltree_add_entry(ubi, vol_id, lnum);
	if (IS_ERR(le))
		return PTR_ERR(le);
	if (down_write_trylock(&le->mutex))
		return 0;

	/* Contention, cancel */
	spin_lock(&ubi->ltree_lock);
	le->users -= 1;
	ubi_assert(le->users >= 0);
	if (le->users == 0) {
		rb_erase(&le->rb, &ubi->ltree);
		kfree(le);
	}
	spin_unlock(&ubi->ltree_lock);

	return 1;
}

/**
 * leb_write_unlock - unlock logical eraseblock.
 * @ubi: UBI device description object
 * @vol_id: volume ID
 * @lnum: logical eraseblock number
 */
static void leb_write_unlock(struct ubi_device *ubi, int vol_id, int lnum)
{
	struct ubi_ltree_entry *le;

	spin_lock(&ubi->ltree_lock);
	le = ltree_lookup(ubi, vol_id, lnum);
	le->users -= 1;
	ubi_assert(le->users >= 0);
	up_write(&le->mutex);
	if (le->users == 0) {
		rb_erase(&le->rb, &ubi->ltree);
		kfree(le);
	}
	spin_unlock(&ubi->ltree_lock);
}

/**
 * ubi_eba_unmap_leb - un-map logical eraseblock.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @lnum: logical eraseblock number
 *
 * This function un-maps logical eraseblock @lnum and schedules corresponding
 * physical eraseblock for erasure. Returns zero in case of success and a
 * negative error code in case of failure.
 */
int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
		      int lnum)
{
	int err, pnum, vol_id = vol->vol_id;

	if (ubi->ro_mode)
		return -EROFS;

	err = leb_write_lock(ubi, vol_id, lnum);
	if (err)
		return err;

	pnum = vol->eba_tbl[lnum];
	if (pnum < 0)
		/* This logical eraseblock is already unmapped */
		goto out_unlock;

	dbg_eba("erase LEB %d:%d, PEB %d", vol_id, lnum, pnum);

	down_read(&ubi->fm_sem);
	vol->eba_tbl[lnum] = UBI_LEB_UNMAPPED;
	up_read(&ubi->fm_sem);
	err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 0);

out_unlock:
	leb_write_unlock(ubi, vol_id, lnum);
	return err;
}

/**
 * ubi_eba_read_leb - read data.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @lnum: logical eraseblock number
 * @buf: buffer to store the read data
 * @offset: offset from where to read
 * @len: how many bytes to read
 * @check: data CRC check flag
 *
 * If the logical eraseblock @lnum is unmapped, @buf is filled with 0xFF
 * bytes. The @check flag only makes sense for static volumes and forces
 * eraseblock data CRC checking.
 *
 * In case of success this function returns zero. In case of a static volume,
 * if data CRC mismatches - %-EBADMSG is returned. %-EBADMSG may also be
 * returned for any volume type if an ECC error was detected by the MTD device
 * driver. Other negative error cored may be returned in case of other errors.
 */
int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
		     void *buf, int offset, int len, int check)
{
	int err, pnum, scrub = 0, vol_id = vol->vol_id;
	struct ubi_vid_hdr *vid_hdr;
	uint32_t uninitialized_var(crc);

	err = leb_read_lock(ubi, vol_id, lnum);
	if (err)
		return err;

	pnum = vol->eba_tbl[lnum];
	if (pnum < 0) {
		/*
		 * The logical eraseblock is not mapped, fill the whole buffer
		 * with 0xFF bytes. The exception is static volumes for which
		 * it is an error to read unmapped logical eraseblocks.
		 */
		dbg_eba("read %d bytes from offset %d of LEB %d:%d (unmapped)",
			len, offset, vol_id, lnum);
		leb_read_unlock(ubi, vol_id, lnum);
		ubi_assert(vol->vol_type != UBI_STATIC_VOLUME);
		memset(buf, 0xFF, len);
		return 0;
	}

	dbg_eba("read %d bytes from offset %d of LEB %d:%d, PEB %d",
		len, offset, vol_id, lnum, pnum);

	if (vol->vol_type == UBI_DYNAMIC_VOLUME)
		check = 0;

retry:
	if (check) {
		vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
		if (!vid_hdr) {
			err = -ENOMEM;
			goto out_unlock;
		}

		err = ubi_io_read_vid_hdr(ubi, pnum, vid_hdr, 1);
		if (err && err != UBI_IO_BITFLIPS) {
			if (err > 0) {
				/*
				 * The header is either absent or corrupted.
				 * The former case means there is a bug -
				 * switch to read-only mode just in case.
				 * The latter case means a real corruption - we
				 * may try to recover data. FIXME: but this is
				 * not implemented.
				 */
				if (err == UBI_IO_BAD_HDR_EBADMSG ||
				    err == UBI_IO_BAD_HDR) {
					ubi_warn("corrupted VID header at PEB %d, LEB %d:%d",
						 pnum, vol_id, lnum);
					err = -EBADMSG;
				} else
					ubi_ro_mode(ubi);
			}
			goto out_free;
		} else if (err == UBI_IO_BITFLIPS)
			scrub = 1;

		ubi_assert(lnum < be32_to_cpu(vid_hdr->used_ebs));
		ubi_assert(len == be32_to_cpu(vid_hdr->data_size));

		crc = be32_to_cpu(vid_hdr->data_crc);
		ubi_free_vid_hdr(ubi, vid_hdr);
	}

	err = ubi_io_read_data(ubi, buf, pnum, offset, len);
	if (err) {
		if (err == UBI_IO_BITFLIPS) {
			scrub = 1;
			err = 0;
		} else if (mtd_is_eccerr(err)) {
			if (vol->vol_type == UBI_DYNAMIC_VOLUME)
				goto out_unlock;
			scrub = 1;
			if (!check) {
				ubi_msg("force data checking");
				check = 1;
				goto retry;
			}
		} else
			goto out_unlock;
	}

	if (check) {
		uint32_t crc1 = crc32(UBI_CRC32_INIT, buf, len);
		if (crc1 != crc) {
			ubi_warn("CRC error: calculated %#08x, must be %#08x",
				 crc1, crc);
			err = -EBADMSG;
			goto out_unlock;
		}
	}

	if (scrub)
		err = ubi_wl_scrub_peb(ubi, pnum);

	leb_read_unlock(ubi, vol_id, lnum);
	return err;

out_free:
	ubi_free_vid_hdr(ubi, vid_hdr);
out_unlock:
	leb_read_unlock(ubi, vol_id, lnum);
	return err;
}

/**
 * recover_peb - recover from write failure.
 * @ubi: UBI device description object
 * @pnum: the physical eraseblock to recover
 * @vol_id: volume ID
 * @lnum: logical eraseblock number
 * @buf: data which was not written because of the write failure
 * @offset: offset of the failed write
 * @len: how many bytes should have been written
 *
 * This function is called in case of a write failure and moves all good data
 * from the potentially bad physical eraseblock to a good physical eraseblock.
 * This function also writes the data which was not written due to the failure.
 * Returns new physical eraseblock number in case of success, and a negative
 * error code in case of failure.
 */
static int recover_peb(struct ubi_device *ubi, int pnum, int vol_id, int lnum,
		       const void *buf, int offset, int len)
{
	int err, idx = vol_id2idx(ubi, vol_id), new_pnum, data_size, tries = 0;
	struct ubi_volume *vol = ubi->volumes[idx];
	struct ubi_vid_hdr *vid_hdr;

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

retry:
	new_pnum = ubi_wl_get_peb(ubi);
	if (new_pnum < 0) {
		ubi_free_vid_hdr(ubi, vid_hdr);
		return new_pnum;
	}

	ubi_msg("recover PEB %d, move data to PEB %d", pnum, new_pnum);

	err = ubi_io_read_vid_hdr(ubi, pnum, vid_hdr, 1);
	if (err && err != UBI_IO_BITFLIPS) {
		if (err > 0)
			err = -EIO;
		goto out_put;
	}

	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
	err = ubi_io_write_vid_hdr(ubi, new_pnum, vid_hdr);
	if (err)
		goto write_error;

	data_size = offset + len;
	mutex_lock(&ubi->buf_mutex);
	memset(ubi->peb_buf + offset, 0xFF, len);

	/* Read everything before the area where the write failure happened */
	if (offset > 0) {
		err = ubi_io_read_data(ubi, ubi->peb_buf, pnum, 0, offset);
		if (err && err != UBI_IO_BITFLIPS)
			goto out_unlock;
	}

	memcpy(ubi->peb_buf + offset, buf, len);

	err = ubi_io_write_data(ubi, ubi->peb_buf, new_pnum, 0, data_size);
	if (err) {
		mutex_unlock(&ubi->buf_mutex);
		goto write_error;
	}

	mutex_unlock(&ubi->buf_mutex);
	ubi_free_vid_hdr(ubi, vid_hdr);

	down_read(&ubi->fm_sem);
	vol->eba_tbl[lnum] = new_pnum;
	up_read(&ubi->fm_sem);
	ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);

	ubi_msg("data was successfully recovered");
	return 0;

out_unlock:
	mutex_unlock(&ubi->buf_mutex);
out_put:
	ubi_wl_put_peb(ubi, vol_id, lnum, new_pnum, 1);
	ubi_free_vid_hdr(ubi, vid_hdr);
	return err;

write_error:
	/*
	 * Bad luck? This physical eraseblock is bad too? Crud. Let's try to
	 * get another one.
	 */
	ubi_warn("failed to write to PEB %d", new_pnum);
	ubi_wl_put_peb(ubi, vol_id, lnum, new_pnum, 1);
	if (++tries > UBI_IO_RETRIES) {
		ubi_free_vid_hdr(ubi, vid_hdr);
		return err;
	}
	ubi_msg("try again");
	goto retry;
}

/**
 * ubi_eba_write_leb - write data to dynamic volume.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @lnum: logical eraseblock number
 * @buf: the data to write
 * @offset: offset within the logical eraseblock where to write
 * @len: how many bytes to write
 *
 * This function writes data to logical eraseblock @lnum of a dynamic volume
 * @vol. Returns zero in case of success and a negative error code in case
 * of failure. In case of error, it is possible that something was still
 * written to the flash media, but may be some garbage.
 */
int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
		      const void *buf, int offset, int len)
{
	int err, pnum, tries = 0, vol_id = vol->vol_id;
	struct ubi_vid_hdr *vid_hdr;

	if (ubi->ro_mode)
		return -EROFS;

	err = leb_write_lock(ubi, vol_id, lnum);
	if (err)
		return err;

	pnum = vol->eba_tbl[lnum];
	if (pnum >= 0) {
		dbg_eba("write %d bytes at offset %d of LEB %d:%d, PEB %d",
			len, offset, vol_id, lnum, pnum);

		err = ubi_io_write_data(ubi, buf, pnum, offset, len);
		if (err) {
			ubi_warn("failed to write data to PEB %d", pnum);
			if (err == -EIO && ubi->bad_allowed)
				err = recover_peb(ubi, pnum, vol_id, lnum, buf,
						  offset, len);
			if (err)
				ubi_ro_mode(ubi);
		}
		leb_write_unlock(ubi, vol_id, lnum);
		return err;
	}

	/*
	 * The logical eraseblock is not mapped. We have to get a free physical
	 * eraseblock and write the volume identifier header there first.
	 */
	vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
	if (!vid_hdr) {
		leb_write_unlock(ubi, vol_id, lnum);
		return -ENOMEM;
	}

	vid_hdr->vol_type = UBI_VID_DYNAMIC;
	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
	vid_hdr->vol_id = cpu_to_be32(vol_id);
	vid_hdr->lnum = cpu_to_be32(lnum);
	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
	vid_hdr->data_pad = cpu_to_be32(vol->data_pad);

retry:
	pnum = ubi_wl_get_peb(ubi);
	if (pnum < 0) {
		ubi_free_vid_hdr(ubi, vid_hdr);
		leb_write_unlock(ubi, vol_id, lnum);
		return pnum;
	}

	dbg_eba("write VID hdr and %d bytes at offset %d of LEB %d:%d, PEB %d",
		len, offset, vol_id, lnum, pnum);

	err = ubi_io_write_vid_hdr(ubi, pnum, vid_hdr);
	if (err) {
		ubi_warn("failed to write VID header to LEB %d:%d, PEB %d",
			 vol_id, lnum, pnum);
		goto write_error;
	}

	if (len) {
		err = ubi_io_write_data(ubi, buf, pnum, offset, len);
		if (err) {
			ubi_warn("failed to write %d bytes at offset %d of LEB %d:%d, PEB %d",
				 len, offset, vol_id, lnum, pnum);
			goto write_error;
		}
	}

	down_read(&ubi->fm_sem);
	vol->eba_tbl[lnum] = pnum;
	up_read(&ubi->fm_sem);

	leb_write_unlock(ubi, vol_id, lnum);
	ubi_free_vid_hdr(ubi, vid_hdr);
	return 0;

write_error:
	if (err != -EIO || !ubi->bad_allowed) {
		ubi_ro_mode(ubi);
		leb_write_unlock(ubi, vol_id, lnum);
		ubi_free_vid_hdr(ubi, vid_hdr);
		return err;
	}

	/*
	 * Fortunately, this is the first write operation to this physical
	 * eraseblock, so just put it and request a new one. We assume that if
	 * this physical eraseblock went bad, the erase code will handle that.
	 */
	err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
	if (err || ++tries > UBI_IO_RETRIES) {
		ubi_ro_mode(ubi);
		leb_write_unlock(ubi, vol_id, lnum);
		ubi_free_vid_hdr(ubi, vid_hdr);
		return err;
	}

	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
	ubi_msg("try another PEB");
	goto retry;
}

/**
 * ubi_eba_write_leb_st - write data to static volume.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @lnum: logical eraseblock number
 * @buf: data to write
 * @len: how many bytes to write
 * @used_ebs: how many logical eraseblocks will this volume contain
 *
 * This function writes data to logical eraseblock @lnum of static volume
 * @vol. The @used_ebs argument should contain total number of logical
 * eraseblock in this static volume.
 *
 * When writing to the last logical eraseblock, the @len argument doesn't have
 * to be aligned to the minimal I/O unit size. Instead, it has to be equivalent
 * to the real data size, although the @buf buffer has to contain the
 * alignment. In all other cases, @len has to be aligned.
 *
 * It is prohibited to write more than once to logical eraseblocks of static
 * volumes. This function returns zero in case of success and a negative error
 * code in case of failure.
 */
int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
			 int lnum, const void *buf, int len, int used_ebs)
{
	int err, pnum, tries = 0, data_size = len, vol_id = vol->vol_id;
	struct ubi_vid_hdr *vid_hdr;
	uint32_t crc;

	if (ubi->ro_mode)
		return -EROFS;

	if (lnum == used_ebs - 1)
		/* If this is the last LEB @len may be unaligned */
		len = ALIGN(data_size, ubi->min_io_size);
	else
		ubi_assert(!(len & (ubi->min_io_size - 1)));

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

	err = leb_write_lock(ubi, vol_id, lnum);
	if (err) {
		ubi_free_vid_hdr(ubi, vid_hdr);
		return err;
	}

	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
	vid_hdr->vol_id = cpu_to_be32(vol_id);
	vid_hdr->lnum = cpu_to_be32(lnum);
	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
	vid_hdr->data_pad = cpu_to_be32(vol->data_pad);

	crc = crc32(UBI_CRC32_INIT, buf, data_size);
	vid_hdr->vol_type = UBI_VID_STATIC;
	vid_hdr->data_size = cpu_to_be32(data_size);
	vid_hdr->used_ebs = cpu_to_be32(used_ebs);
	vid_hdr->data_crc = cpu_to_be32(crc);

retry:
	pnum = ubi_wl_get_peb(ubi);
	if (pnum < 0) {
		ubi_free_vid_hdr(ubi, vid_hdr);
		leb_write_unlock(ubi, vol_id, lnum);
		return pnum;
	}

	dbg_eba("write VID hdr and %d bytes at LEB %d:%d, PEB %d, used_ebs %d",
		len, vol_id, lnum, pnum, used_ebs);

	err = ubi_io_write_vid_hdr(ubi, pnum, vid_hdr);
	if (err) {
		ubi_warn("failed to write VID header to LEB %d:%d, PEB %d",
			 vol_id, lnum, pnum);
		goto write_error;
	}

	err = ubi_io_write_data(ubi, buf, pnum, 0, len);
	if (err) {
		ubi_warn("failed to write %d bytes of data to PEB %d",
			 len, pnum);
		goto write_error;
	}

	ubi_assert(vol->eba_tbl[lnum] < 0);
	down_read(&ubi->fm_sem);
	vol->eba_tbl[lnum] = pnum;
	up_read(&ubi->fm_sem);

	leb_write_unlock(ubi, vol_id, lnum);
	ubi_free_vid_hdr(ubi, vid_hdr);
	return 0;

write_error:
	if (err != -EIO || !ubi->bad_allowed) {
		/*
		 * This flash device does not admit of bad eraseblocks or
		 * something nasty and unexpected happened. Switch to read-only
		 * mode just in case.
		 */
		ubi_ro_mode(ubi);
		leb_write_unlock(ubi, vol_id, lnum);
		ubi_free_vid_hdr(ubi, vid_hdr);
		return err;
	}

	err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
	if (err || ++tries > UBI_IO_RETRIES) {
		ubi_ro_mode(ubi);
		leb_write_unlock(ubi, vol_id, lnum);
		ubi_free_vid_hdr(ubi, vid_hdr);
		return err;
	}

	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
	ubi_msg("try another PEB");
	goto retry;
}

/*
 * ubi_eba_atomic_leb_change - change logical eraseblock atomically.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @lnum: logical eraseblock number
 * @buf: data to write
 * @len: how many bytes to write
 *
 * This function changes the contents of a logical eraseblock atomically. @buf
 * has to contain new logical eraseblock data, and @len - the length of the
 * data, which has to be aligned. This function guarantees that in case of an
 * unclean reboot the old contents is preserved. Returns zero in case of
 * success and a negative error code in case of failure.
 *
 * UBI reserves one LEB for the "atomic LEB change" operation, so only one
 * LEB change may be done at a time. This is ensured by @ubi->alc_mutex.
 */
int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
			      int lnum, const void *buf, int len)
{
	int err, pnum, tries = 0, vol_id = vol->vol_id;
	struct ubi_vid_hdr *vid_hdr;
	uint32_t crc;

	if (ubi->ro_mode)
		return -EROFS;

	if (len == 0) {
		/*
		 * Special case when data length is zero. In this case the LEB
		 * has to be unmapped and mapped somewhere else.
		 */
		err = ubi_eba_unmap_leb(ubi, vol, lnum);
		if (err)
			return err;
		return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0);
	}

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

	mutex_lock(&ubi->alc_mutex);
	err = leb_write_lock(ubi, vol_id, lnum);
	if (err)
		goto out_mutex;

	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
	vid_hdr->vol_id = cpu_to_be32(vol_id);
	vid_hdr->lnum = cpu_to_be32(lnum);
	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
	vid_hdr->data_pad = cpu_to_be32(vol->data_pad);

	crc = crc32(UBI_CRC32_INIT, buf, len);
	vid_hdr->vol_type = UBI_VID_DYNAMIC;
	vid_hdr->data_size = cpu_to_be32(len);
	vid_hdr->copy_flag = 1;
	vid_hdr->data_crc = cpu_to_be32(crc);

retry:
	pnum = ubi_wl_get_peb(ubi);
	if (pnum < 0) {
		err = pnum;
		goto out_leb_unlock;
	}

	dbg_eba("change LEB %d:%d, PEB %d, write VID hdr to PEB %d",
		vol_id, lnum, vol->eba_tbl[lnum], pnum);

	err = ubi_io_write_vid_hdr(ubi, pnum, vid_hdr);
	if (err) {
		ubi_warn("failed to write VID header to LEB %d:%d, PEB %d",
			 vol_id, lnum, pnum);
		goto write_error;
	}

	err = ubi_io_write_data(ubi, buf, pnum, 0, len);
	if (err) {
		ubi_warn("failed to write %d bytes of data to PEB %d",
			 len, pnum);
		goto write_error;
	}

	if (vol->eba_tbl[lnum] >= 0) {
		err = ubi_wl_put_peb(ubi, vol_id, lnum, vol->eba_tbl[lnum], 0);
		if (err)
			goto out_leb_unlock;
	}

	down_read(&ubi->fm_sem);
	vol->eba_tbl[lnum] = pnum;
	up_read(&ubi->fm_sem);

out_leb_unlock:
	leb_write_unlock(ubi, vol_id, lnum);
out_mutex:
	mutex_unlock(&ubi->alc_mutex);
	ubi_free_vid_hdr(ubi, vid_hdr);
	return err;

write_error:
	if (err != -EIO || !ubi->bad_allowed) {
		/*
		 * This flash device does not admit of bad eraseblocks or
		 * something nasty and unexpected happened. Switch to read-only
		 * mode just in case.
		 */
		ubi_ro_mode(ubi);
		goto out_leb_unlock;
	}

	err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
	if (err || ++tries > UBI_IO_RETRIES) {
		ubi_ro_mode(ubi);
		goto out_leb_unlock;
	}

	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
	ubi_msg("try another PEB");
	goto retry;
}

/**
 * is_error_sane - check whether a read error is sane.
 * @err: code of the error happened during reading
 *
 * This is a helper function for 'ubi_eba_copy_leb()' which is called when we
 * cannot read data from the target PEB (an error @err happened). If the error
 * code is sane, then we treat this error as non-fatal. Otherwise the error is
 * fatal and UBI will be switched to R/O mode later.
 *
 * The idea is that we try not to switch to R/O mode if the read error is
 * something which suggests there was a real read problem. E.g., %-EIO. Or a
 * memory allocation failed (-%ENOMEM). Otherwise, it is safer to switch to R/O
 * mode, simply because we do not know what happened at the MTD level, and we
 * cannot handle this. E.g., the underlying driver may have become crazy, and
 * it is safer to switch to R/O mode to preserve the data.
 *
 * And bear in mind, this is about reading from the target PEB, i.e. the PEB
 * which we have just written.
 */
static int is_error_sane(int err)
{
	if (err == -EIO || err == -ENOMEM || err == UBI_IO_BAD_HDR ||
	    err == UBI_IO_BAD_HDR_EBADMSG || err == -ETIMEDOUT)
		return 0;
	return 1;
}

/**
 * ubi_eba_copy_leb - copy logical eraseblock.
 * @ubi: UBI device description object
 * @from: physical eraseblock number from where to copy
 * @to: physical eraseblock number where to copy
 * @vid_hdr: VID header of the @from physical eraseblock
 *
 * This function copies logical eraseblock from physical eraseblock @from to
 * physical eraseblock @to. The @vid_hdr buffer may be changed by this
 * function. Returns:
 *   o %0 in case of success;
 *   o %MOVE_CANCEL_RACE, %MOVE_TARGET_WR_ERR, %MOVE_TARGET_BITFLIPS, etc;
 *   o a negative error code in case of failure.
 */
int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
		     struct ubi_vid_hdr *vid_hdr)
{
	int err, vol_id, lnum, data_size, aldata_size, idx;
	struct ubi_volume *vol;
	uint32_t crc;

	vol_id = be32_to_cpu(vid_hdr->vol_id);
	lnum = be32_to_cpu(vid_hdr->lnum);

	dbg_wl("copy LEB %d:%d, PEB %d to PEB %d", vol_id, lnum, from, to);

	if (vid_hdr->vol_type == UBI_VID_STATIC) {
		data_size = be32_to_cpu(vid_hdr->data_size);
		aldata_size = ALIGN(data_size, ubi->min_io_size);
	} else
		data_size = aldata_size =
			    ubi->leb_size - be32_to_cpu(vid_hdr->data_pad);

	idx = vol_id2idx(ubi, vol_id);
	spin_lock(&ubi->volumes_lock);
	/*
	 * Note, we may race with volume deletion, which means that the volume
	 * this logical eraseblock belongs to might be being deleted. Since the
	 * volume deletion un-maps all the volume's logical eraseblocks, it will
	 * be locked in 'ubi_wl_put_peb()' and wait for the WL worker to finish.
	 */
	vol = ubi->volumes[idx];
	spin_unlock(&ubi->volumes_lock);
	if (!vol) {
		/* No need to do further work, cancel */
		dbg_wl("volume %d is being removed, cancel", vol_id);
		return MOVE_CANCEL_RACE;
	}

	/*
	 * We do not want anybody to write to this logical eraseblock while we
	 * are moving it, so lock it.
	 *
	 * Note, we are using non-waiting locking here, because we cannot sleep
	 * on the LEB, since it may cause deadlocks. Indeed, imagine a task is
	 * unmapping the LEB which is mapped to the PEB we are going to move
	 * (@from). This task locks the LEB and goes sleep in the
	 * 'ubi_wl_put_peb()' function on the @ubi->move_mutex. In turn, we are
	 * holding @ubi->move_mutex and go sleep on the LEB lock. So, if the
	 * LEB is already locked, we just do not move it and return
	 * %MOVE_RETRY. Note, we do not return %MOVE_CANCEL_RACE here because
	 * we do not know the reasons of the contention - it may be just a
	 * normal I/O on this LEB, so we want to re-try.
	 */
	err = leb_write_trylock(ubi, vol_id, lnum);
	if (err) {
		dbg_wl("contention on LEB %d:%d, cancel", vol_id, lnum);
		return MOVE_RETRY;
	}

	/*
	 * The LEB might have been put meanwhile, and the task which put it is
	 * probably waiting on @ubi->move_mutex. No need to continue the work,
	 * cancel it.
	 */
	if (vol->eba_tbl[lnum] != from) {
		dbg_wl("LEB %d:%d is no longer mapped to PEB %d, mapped to PEB %d, cancel",
		       vol_id, lnum, from, vol->eba_tbl[lnum]);
		err = MOVE_CANCEL_RACE;
		goto out_unlock_leb;
	}

	/*
	 * OK, now the LEB is locked and we can safely start moving it. Since
	 * this function utilizes the @ubi->peb_buf buffer which is shared
	 * with some other functions - we lock the buffer by taking the
	 * @ubi->buf_mutex.
	 */
	mutex_lock(&ubi->buf_mutex);
	dbg_wl("read %d bytes of data", aldata_size);
	err = ubi_io_read_data(ubi, ubi->peb_buf, from, 0, aldata_size);
	if (err && err != UBI_IO_BITFLIPS) {
		ubi_warn("error %d while reading data from PEB %d",
			 err, from);
		err = MOVE_SOURCE_RD_ERR;
		goto out_unlock_buf;
	}

	/*
	 * Now we have got to calculate how much data we have to copy. In
	 * case of a static volume it is fairly easy - the VID header contains
	 * the data size. In case of a dynamic volume it is more difficult - we
	 * have to read the contents, cut 0xFF bytes from the end and copy only
	 * the first part. We must do this to avoid writing 0xFF bytes as it
	 * may have some side-effects. And not only this. It is important not
	 * to include those 0xFFs to CRC because later the they may be filled
	 * by data.
	 */
	if (vid_hdr->vol_type == UBI_VID_DYNAMIC)
		aldata_size = data_size =
			ubi_calc_data_len(ubi, ubi->peb_buf, data_size);

	cond_resched();
	crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size);
	cond_resched();

	/*
	 * It may turn out to be that the whole @from physical eraseblock
	 * contains only 0xFF bytes. Then we have to only write the VID header
	 * and do not write any data. This also means we should not set
	 * @vid_hdr->copy_flag, @vid_hdr->data_size, and @vid_hdr->data_crc.
	 */
	if (data_size > 0) {
		vid_hdr->copy_flag = 1;
		vid_hdr->data_size = cpu_to_be32(data_size);
		vid_hdr->data_crc = cpu_to_be32(crc);
	}
	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));

	err = ubi_io_write_vid_hdr(ubi, to, vid_hdr);
	if (err) {
		if (err == -EIO)
			err = MOVE_TARGET_WR_ERR;
		goto out_unlock_buf;
	}

	cond_resched();

	/* Read the VID header back and check if it was written correctly */
	err = ubi_io_read_vid_hdr(ubi, to, vid_hdr, 1);
	if (err) {
		if (err != UBI_IO_BITFLIPS) {
			ubi_warn("error %d while reading VID header back from PEB %d",
				 err, to);
			if (is_error_sane(err))
				err = MOVE_TARGET_RD_ERR;
		} else
			err = MOVE_TARGET_BITFLIPS;
		goto out_unlock_buf;
	}

	if (data_size > 0) {
		err = ubi_io_write_data(ubi, ubi->peb_buf, to, 0, aldata_size);
		if (err) {
			if (err == -EIO)
				err = MOVE_TARGET_WR_ERR;
			goto out_unlock_buf;
		}

		cond_resched();

		/*
		 * We've written the data and are going to read it back to make
		 * sure it was written correctly.
		 */
		memset(ubi->peb_buf, 0xFF, aldata_size);
		err = ubi_io_read_data(ubi, ubi->peb_buf, to, 0, aldata_size);
		if (err) {
			if (err != UBI_IO_BITFLIPS) {
				ubi_warn("error %d while reading data back from PEB %d",
					 err, to);
				if (is_error_sane(err))
					err = MOVE_TARGET_RD_ERR;
			} else
				err = MOVE_TARGET_BITFLIPS;
			goto out_unlock_buf;
		}

		cond_resched();

		if (crc != crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size)) {
			ubi_warn("read data back from PEB %d and it is different",
				 to);
			err = -EINVAL;
			goto out_unlock_buf;
		}
	}

	ubi_assert(vol->eba_tbl[lnum] == from);
	down_read(&ubi->fm_sem);
	vol->eba_tbl[lnum] = to;
	up_read(&ubi->fm_sem);

out_unlock_buf:
	mutex_unlock(&ubi->buf_mutex);
out_unlock_leb:
	leb_write_unlock(ubi, vol_id, lnum);
	return err;
}

/**
 * print_rsvd_warning - warn about not having enough reserved PEBs.
 * @ubi: UBI device description object
 *
 * This is a helper function for 'ubi_eba_init()' which is called when UBI
 * cannot reserve enough PEBs for bad block handling. This function makes a
 * decision whether we have to print a warning or not. The algorithm is as
 * follows:
 *   o if this is a new UBI image, then just print the warning
 *   o if this is an UBI image which has already been used for some time, print
 *     a warning only if we can reserve less than 10% of the expected amount of
 *     the reserved PEB.
 *
 * The idea is that when UBI is used, PEBs become bad, and the reserved pool
 * of PEBs becomes smaller, which is normal and we do not want to scare users
 * with a warning every time they attach the MTD device. This was an issue
 * reported by real users.
 */
static void print_rsvd_warning(struct ubi_device *ubi,
			       struct ubi_attach_info *ai)
{
	/*
	 * The 1 << 18 (256KiB) number is picked randomly, just a reasonably
	 * large number to distinguish between newly flashed and used images.
	 */
	if (ai->max_sqnum > (1 << 18)) {
		int min = ubi->beb_rsvd_level / 10;

		if (!min)
			min = 1;
		if (ubi->beb_rsvd_pebs > min)
			return;
	}

	ubi_warn("cannot reserve enough PEBs for bad PEB handling, reserved %d, need %d",
		 ubi->beb_rsvd_pebs, ubi->beb_rsvd_level);
	if (ubi->corr_peb_count)
		ubi_warn("%d PEBs are corrupted and not used",
			 ubi->corr_peb_count);
}

/**
 * self_check_eba - run a self check on the EBA table constructed by fastmap.
 * @ubi: UBI device description object
 * @ai_fastmap: UBI attach info object created by fastmap
 * @ai_scan: UBI attach info object created by scanning
 *
 * Returns < 0 in case of an internal error, 0 otherwise.
 * If a bad EBA table entry was found it will be printed out and
 * ubi_assert() triggers.
 */
int self_check_eba(struct ubi_device *ubi, struct ubi_attach_info *ai_fastmap,
		   struct ubi_attach_info *ai_scan)
{
	int i, j, num_volumes, ret = 0;
	int **scan_eba, **fm_eba;
	struct ubi_ainf_volume *av;
	struct ubi_volume *vol;
	struct ubi_ainf_peb *aeb;
	struct rb_node *rb;

	num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;

	scan_eba = kmalloc(sizeof(*scan_eba) * num_volumes, GFP_KERNEL);
	if (!scan_eba)
		return -ENOMEM;

	fm_eba = kmalloc(sizeof(*fm_eba) * num_volumes, GFP_KERNEL);
	if (!fm_eba) {
		kfree(scan_eba);
		return -ENOMEM;
	}

	for (i = 0; i < num_volumes; i++) {
		vol = ubi->volumes[i];
		if (!vol)
			continue;

		scan_eba[i] = kmalloc(vol->reserved_pebs * sizeof(**scan_eba),
				      GFP_KERNEL);
		if (!scan_eba[i]) {
			ret = -ENOMEM;
			goto out_free;
		}

		fm_eba[i] = kmalloc(vol->reserved_pebs * sizeof(**fm_eba),
				    GFP_KERNEL);
		if (!fm_eba[i]) {
			ret = -ENOMEM;
			goto out_free;
		}

		for (j = 0; j < vol->reserved_pebs; j++)
			scan_eba[i][j] = fm_eba[i][j] = UBI_LEB_UNMAPPED;

		av = ubi_find_av(ai_scan, idx2vol_id(ubi, i));
		if (!av)
			continue;

		ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb)
			scan_eba[i][aeb->lnum] = aeb->pnum;

		av = ubi_find_av(ai_fastmap, idx2vol_id(ubi, i));
		if (!av)
			continue;

		ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb)
			fm_eba[i][aeb->lnum] = aeb->pnum;

		for (j = 0; j < vol->reserved_pebs; j++) {
			if (scan_eba[i][j] != fm_eba[i][j]) {
				if (scan_eba[i][j] == UBI_LEB_UNMAPPED ||
					fm_eba[i][j] == UBI_LEB_UNMAPPED)
					continue;

				ubi_err("LEB:%i:%i is PEB:%i instead of %i!",
					vol->vol_id, i, fm_eba[i][j],
					scan_eba[i][j]);
				ubi_assert(0);
			}
		}
	}

out_free:
	for (i = 0; i < num_volumes; i++) {
		if (!ubi->volumes[i])
			continue;

		kfree(scan_eba[i]);
		kfree(fm_eba[i]);
	}

	kfree(scan_eba);
	kfree(fm_eba);
	return ret;
}

/**
 * ubi_eba_init - initialize the EBA sub-system using attaching information.
 * @ubi: UBI device description object
 * @ai: attaching information
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
int ubi_eba_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
{
	int i, j, err, num_volumes;
	struct ubi_ainf_volume *av;
	struct ubi_volume *vol;
	struct ubi_ainf_peb *aeb;
	struct rb_node *rb;

	dbg_eba("initialize EBA sub-system");

	spin_lock_init(&ubi->ltree_lock);
	mutex_init(&ubi->alc_mutex);
	ubi->ltree = RB_ROOT;

	ubi->global_sqnum = ai->max_sqnum + 1;
	num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;

	for (i = 0; i < num_volumes; i++) {
		vol = ubi->volumes[i];
		if (!vol)
			continue;

		cond_resched();

		vol->eba_tbl = kmalloc(vol->reserved_pebs * sizeof(int),
				       GFP_KERNEL);
		if (!vol->eba_tbl) {
			err = -ENOMEM;
			goto out_free;
		}

		for (j = 0; j < vol->reserved_pebs; j++)
			vol->eba_tbl[j] = UBI_LEB_UNMAPPED;

		av = ubi_find_av(ai, idx2vol_id(ubi, i));
		if (!av)
			continue;

		ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb) {
			if (aeb->lnum >= vol->reserved_pebs)
				/*
				 * This may happen in case of an unclean reboot
				 * during re-size.
				 */
				ubi_move_aeb_to_list(av, aeb, &ai->erase);
			vol->eba_tbl[aeb->lnum] = aeb->pnum;
		}
	}

	if (ubi->avail_pebs < EBA_RESERVED_PEBS) {
		ubi_err("no enough physical eraseblocks (%d, need %d)",
			ubi->avail_pebs, EBA_RESERVED_PEBS);
		if (ubi->corr_peb_count)
			ubi_err("%d PEBs are corrupted and not used",
				ubi->corr_peb_count);
		err = -ENOSPC;
		goto out_free;
	}
	ubi->avail_pebs -= EBA_RESERVED_PEBS;
	ubi->rsvd_pebs += EBA_RESERVED_PEBS;

	if (ubi->bad_allowed) {
		ubi_calculate_reserved(ubi);

		if (ubi->avail_pebs < ubi->beb_rsvd_level) {
			/* No enough free physical eraseblocks */
			ubi->beb_rsvd_pebs = ubi->avail_pebs;
			print_rsvd_warning(ubi, ai);
		} else
			ubi->beb_rsvd_pebs = ubi->beb_rsvd_level;

		ubi->avail_pebs -= ubi->beb_rsvd_pebs;
		ubi->rsvd_pebs  += ubi->beb_rsvd_pebs;
	}

	dbg_eba("EBA sub-system is initialized");
	return 0;

out_free:
	for (i = 0; i < num_volumes; i++) {
		if (!ubi->volumes[i])
			continue;
		kfree(ubi->volumes[i]->eba_tbl);
		ubi->volumes[i]->eba_tbl = NULL;
	}
	return err;
}