aboutsummaryrefslogtreecommitdiff
path: root/fs/ubifs/lpt.c
blob: cd11b23a18754136933fe64945c331177ea2e299 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Adrian Hunter
 *          Artem Bityutskiy (Битюцкий Артём)
 */

/*
 * This file implements the LEB properties tree (LPT) area. The LPT area
 * contains the LEB properties tree, a table of LPT area eraseblocks (ltab), and
 * (for the "big" model) a table of saved LEB numbers (lsave). The LPT area sits
 * between the log and the orphan area.
 *
 * The LPT area is like a miniature self-contained file system. It is required
 * that it never runs out of space, is fast to access and update, and scales
 * logarithmically. The LEB properties tree is implemented as a wandering tree
 * much like the TNC, and the LPT area has its own garbage collection.
 *
 * The LPT has two slightly different forms called the "small model" and the
 * "big model". The small model is used when the entire LEB properties table
 * can be written into a single eraseblock. In that case, garbage collection
 * consists of just writing the whole table, which therefore makes all other
 * eraseblocks reusable. In the case of the big model, dirty eraseblocks are
 * selected for garbage collection, which consists are marking the nodes in
 * that LEB as dirty, and then only the dirty nodes are written out. Also, in
 * the case of the big model, a table of LEB numbers is saved so that the entire
 * LPT does not to be scanned looking for empty eraseblocks when UBIFS is first
 * mounted.
 */

#include <linux/crc16.h>
#include "ubifs.h"

/**
 * do_calc_lpt_geom - calculate sizes for the LPT area.
 * @c: the UBIFS file-system description object
 *
 * Calculate the sizes of LPT bit fields, nodes, and tree, based on the
 * properties of the flash and whether LPT is "big" (c->big_lpt).
 */
static void do_calc_lpt_geom(struct ubifs_info *c)
{
	int i, n, bits, per_leb_wastage, max_pnode_cnt;
	long long sz, tot_wastage;

	n = c->main_lebs + c->max_leb_cnt - c->leb_cnt;
	max_pnode_cnt = DIV_ROUND_UP(n, UBIFS_LPT_FANOUT);

	c->lpt_hght = 1;
	n = UBIFS_LPT_FANOUT;
	while (n < max_pnode_cnt) {
		c->lpt_hght += 1;
		n <<= UBIFS_LPT_FANOUT_SHIFT;
	}

	c->pnode_cnt = DIV_ROUND_UP(c->main_lebs, UBIFS_LPT_FANOUT);

	n = DIV_ROUND_UP(c->pnode_cnt, UBIFS_LPT_FANOUT);
	c->nnode_cnt = n;
	for (i = 1; i < c->lpt_hght; i++) {
		n = DIV_ROUND_UP(n, UBIFS_LPT_FANOUT);
		c->nnode_cnt += n;
	}

	c->space_bits = fls(c->leb_size) - 3;
	c->lpt_lnum_bits = fls(c->lpt_lebs);
	c->lpt_offs_bits = fls(c->leb_size - 1);
	c->lpt_spc_bits = fls(c->leb_size);

	n = DIV_ROUND_UP(c->max_leb_cnt, UBIFS_LPT_FANOUT);
	c->pcnt_bits = fls(n - 1);

	c->lnum_bits = fls(c->max_leb_cnt - 1);

	bits = UBIFS_LPT_CRC_BITS + UBIFS_LPT_TYPE_BITS +
	       (c->big_lpt ? c->pcnt_bits : 0) +
	       (c->space_bits * 2 + 1) * UBIFS_LPT_FANOUT;
	c->pnode_sz = (bits + 7) / 8;

	bits = UBIFS_LPT_CRC_BITS + UBIFS_LPT_TYPE_BITS +
	       (c->big_lpt ? c->pcnt_bits : 0) +
	       (c->lpt_lnum_bits + c->lpt_offs_bits) * UBIFS_LPT_FANOUT;
	c->nnode_sz = (bits + 7) / 8;

	bits = UBIFS_LPT_CRC_BITS + UBIFS_LPT_TYPE_BITS +
	       c->lpt_lebs * c->lpt_spc_bits * 2;
	c->ltab_sz = (bits + 7) / 8;

	bits = UBIFS_LPT_CRC_BITS + UBIFS_LPT_TYPE_BITS +
	       c->lnum_bits * c->lsave_cnt;
	c->lsave_sz = (bits + 7) / 8;

	/* Calculate the minimum LPT size */
	c->lpt_sz = (long long)c->pnode_cnt * c->pnode_sz;
	c->lpt_sz += (long long)c->nnode_cnt * c->nnode_sz;
	c->lpt_sz += c->ltab_sz;
	if (c->big_lpt)
		c->lpt_sz += c->lsave_sz;

	/* Add wastage */
	sz = c->lpt_sz;
	per_leb_wastage = max_t(int, c->pnode_sz, c->nnode_sz);
	sz += per_leb_wastage;
	tot_wastage = per_leb_wastage;
	while (sz > c->leb_size) {
		sz += per_leb_wastage;
		sz -= c->leb_size;
		tot_wastage += per_leb_wastage;
	}
	tot_wastage += ALIGN(sz, c->min_io_size) - sz;
	c->lpt_sz += tot_wastage;
}

/**
 * ubifs_calc_lpt_geom - calculate and check sizes for the LPT area.
 * @c: the UBIFS file-system description object
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_calc_lpt_geom(struct ubifs_info *c)
{
	int lebs_needed;
	uint64_t sz;

	do_calc_lpt_geom(c);

	/* Verify that lpt_lebs is big enough */
	sz = c->lpt_sz * 2; /* Must have at least 2 times the size */
	sz += c->leb_size - 1;
	do_div(sz, c->leb_size);
	lebs_needed = sz;
	if (lebs_needed > c->lpt_lebs) {
		ubifs_err("too few LPT LEBs");
		return -EINVAL;
	}

	/* Verify that ltab fits in a single LEB (since ltab is a single node */
	if (c->ltab_sz > c->leb_size) {
		ubifs_err("LPT ltab too big");
		return -EINVAL;
	}

	c->check_lpt_free = c->big_lpt;

	return 0;
}

/**
 * calc_dflt_lpt_geom - calculate default LPT geometry.
 * @c: the UBIFS file-system description object
 * @main_lebs: number of main area LEBs is passed and returned here
 * @big_lpt: whether the LPT area is "big" is returned here
 *
 * The size of the LPT area depends on parameters that themselves are dependent
 * on the size of the LPT area. This function, successively recalculates the LPT
 * area geometry until the parameters and resultant geometry are consistent.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int calc_dflt_lpt_geom(struct ubifs_info *c, int *main_lebs,
			      int *big_lpt)
{
	int i, lebs_needed;
	uint64_t sz;

	/* Start by assuming the minimum number of LPT LEBs */
	c->lpt_lebs = UBIFS_MIN_LPT_LEBS;
	c->main_lebs = *main_lebs - c->lpt_lebs;
	if (c->main_lebs <= 0)
		return -EINVAL;

	/* And assume we will use the small LPT model */
	c->big_lpt = 0;

	/*
	 * Calculate the geometry based on assumptions above and then see if it
	 * makes sense
	 */
	do_calc_lpt_geom(c);

	/* Small LPT model must have lpt_sz < leb_size */
	if (c->lpt_sz > c->leb_size) {
		/* Nope, so try again using big LPT model */
		c->big_lpt = 1;
		do_calc_lpt_geom(c);
	}

	/* Now check there are enough LPT LEBs */
	for (i = 0; i < 64 ; i++) {
		sz = c->lpt_sz * 4; /* Allow 4 times the size */
		sz += c->leb_size - 1;
		do_div(sz, c->leb_size);
		lebs_needed = sz;
		if (lebs_needed > c->lpt_lebs) {
			/* Not enough LPT LEBs so try again with more */
			c->lpt_lebs = lebs_needed;
			c->main_lebs = *main_lebs - c->lpt_lebs;
			if (c->main_lebs <= 0)
				return -EINVAL;
			do_calc_lpt_geom(c);
			continue;
		}
		if (c->ltab_sz > c->leb_size) {
			ubifs_err("LPT ltab too big");
			return -EINVAL;
		}
		*main_lebs = c->main_lebs;
		*big_lpt = c->big_lpt;
		return 0;
	}
	return -EINVAL;
}

/**
 * pack_bits - pack bit fields end-to-end.
 * @addr: address at which to pack (passed and next address returned)
 * @pos: bit position at which to pack (passed and next position returned)
 * @val: value to pack
 * @nrbits: number of bits of value to pack (1-32)
 */
static void pack_bits(uint8_t **addr, int *pos, uint32_t val, int nrbits)
{
	uint8_t *p = *addr;
	int b = *pos;

	ubifs_assert(nrbits > 0);
	ubifs_assert(nrbits <= 32);
	ubifs_assert(*pos >= 0);
	ubifs_assert(*pos < 8);
	ubifs_assert((val >> nrbits) == 0 || nrbits == 32);
	if (b) {
		*p |= ((uint8_t)val) << b;
		nrbits += b;
		if (nrbits > 8) {
			*++p = (uint8_t)(val >>= (8 - b));
			if (nrbits > 16) {
				*++p = (uint8_t)(val >>= 8);
				if (nrbits > 24) {
					*++p = (uint8_t)(val >>= 8);
					if (nrbits > 32)
						*++p = (uint8_t)(val >>= 8);
				}
			}
		}
	} else {
		*p = (uint8_t)val;
		if (nrbits > 8) {
			*++p = (uint8_t)(val >>= 8);
			if (nrbits > 16) {
				*++p = (uint8_t)(val >>= 8);
				if (nrbits > 24)
					*++p = (uint8_t)(val >>= 8);
			}
		}
	}
	b = nrbits & 7;
	if (b == 0)
		p++;
	*addr = p;
	*pos = b;
}

/**
 * ubifs_unpack_bits - unpack bit fields.
 * @addr: address at which to unpack (passed and next address returned)
 * @pos: bit position at which to unpack (passed and next position returned)
 * @nrbits: number of bits of value to unpack (1-32)
 *
 * This functions returns the value unpacked.
 */
uint32_t ubifs_unpack_bits(uint8_t **addr, int *pos, int nrbits)
{
	const int k = 32 - nrbits;
	uint8_t *p = *addr;
	int b = *pos;
	uint32_t val;

	ubifs_assert(nrbits > 0);
	ubifs_assert(nrbits <= 32);
	ubifs_assert(*pos >= 0);
	ubifs_assert(*pos < 8);
	if (b) {
		val = p[1] | ((uint32_t)p[2] << 8) | ((uint32_t)p[3] << 16) |
		      ((uint32_t)p[4] << 24);
		val <<= (8 - b);
		val |= *p >> b;
		nrbits += b;
	} else
		val = p[0] | ((uint32_t)p[1] << 8) | ((uint32_t)p[2] << 16) |
		      ((uint32_t)p[3] << 24);
	val <<= k;
	val >>= k;
	b = nrbits & 7;
	p += nrbits / 8;
	*addr = p;
	*pos = b;
	ubifs_assert((val >> nrbits) == 0 || nrbits - b == 32);
	return val;
}

/**
 * ubifs_pack_pnode - pack all the bit fields of a pnode.
 * @c: UBIFS file-system description object
 * @buf: buffer into which to pack
 * @pnode: pnode to pack
 */
void ubifs_pack_pnode(struct ubifs_info *c, void *buf,
		      struct ubifs_pnode *pnode)
{
	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
	int i, pos = 0;
	uint16_t crc;

	pack_bits(&addr, &pos, UBIFS_LPT_PNODE, UBIFS_LPT_TYPE_BITS);
	if (c->big_lpt)
		pack_bits(&addr, &pos, pnode->num, c->pcnt_bits);
	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		pack_bits(&addr, &pos, pnode->lprops[i].free >> 3,
			  c->space_bits);
		pack_bits(&addr, &pos, pnode->lprops[i].dirty >> 3,
			  c->space_bits);
		if (pnode->lprops[i].flags & LPROPS_INDEX)
			pack_bits(&addr, &pos, 1, 1);
		else
			pack_bits(&addr, &pos, 0, 1);
	}
	crc = crc16(-1, buf + UBIFS_LPT_CRC_BYTES,
		    c->pnode_sz - UBIFS_LPT_CRC_BYTES);
	addr = buf;
	pos = 0;
	pack_bits(&addr, &pos, crc, UBIFS_LPT_CRC_BITS);
}

/**
 * ubifs_pack_nnode - pack all the bit fields of a nnode.
 * @c: UBIFS file-system description object
 * @buf: buffer into which to pack
 * @nnode: nnode to pack
 */
void ubifs_pack_nnode(struct ubifs_info *c, void *buf,
		      struct ubifs_nnode *nnode)
{
	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
	int i, pos = 0;
	uint16_t crc;

	pack_bits(&addr, &pos, UBIFS_LPT_NNODE, UBIFS_LPT_TYPE_BITS);
	if (c->big_lpt)
		pack_bits(&addr, &pos, nnode->num, c->pcnt_bits);
	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		int lnum = nnode->nbranch[i].lnum;

		if (lnum == 0)
			lnum = c->lpt_last + 1;
		pack_bits(&addr, &pos, lnum - c->lpt_first, c->lpt_lnum_bits);
		pack_bits(&addr, &pos, nnode->nbranch[i].offs,
			  c->lpt_offs_bits);
	}
	crc = crc16(-1, buf + UBIFS_LPT_CRC_BYTES,
		    c->nnode_sz - UBIFS_LPT_CRC_BYTES);
	addr = buf;
	pos = 0;
	pack_bits(&addr, &pos, crc, UBIFS_LPT_CRC_BITS);
}

/**
 * ubifs_pack_ltab - pack the LPT's own lprops table.
 * @c: UBIFS file-system description object
 * @buf: buffer into which to pack
 * @ltab: LPT's own lprops table to pack
 */
void ubifs_pack_ltab(struct ubifs_info *c, void *buf,
		     struct ubifs_lpt_lprops *ltab)
{
	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
	int i, pos = 0;
	uint16_t crc;

	pack_bits(&addr, &pos, UBIFS_LPT_LTAB, UBIFS_LPT_TYPE_BITS);
	for (i = 0; i < c->lpt_lebs; i++) {
		pack_bits(&addr, &pos, ltab[i].free, c->lpt_spc_bits);
		pack_bits(&addr, &pos, ltab[i].dirty, c->lpt_spc_bits);
	}
	crc = crc16(-1, buf + UBIFS_LPT_CRC_BYTES,
		    c->ltab_sz - UBIFS_LPT_CRC_BYTES);
	addr = buf;
	pos = 0;
	pack_bits(&addr, &pos, crc, UBIFS_LPT_CRC_BITS);
}

/**
 * ubifs_pack_lsave - pack the LPT's save table.
 * @c: UBIFS file-system description object
 * @buf: buffer into which to pack
 * @lsave: LPT's save table to pack
 */
void ubifs_pack_lsave(struct ubifs_info *c, void *buf, int *lsave)
{
	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
	int i, pos = 0;
	uint16_t crc;

	pack_bits(&addr, &pos, UBIFS_LPT_LSAVE, UBIFS_LPT_TYPE_BITS);
	for (i = 0; i < c->lsave_cnt; i++)
		pack_bits(&addr, &pos, lsave[i], c->lnum_bits);
	crc = crc16(-1, buf + UBIFS_LPT_CRC_BYTES,
		    c->lsave_sz - UBIFS_LPT_CRC_BYTES);
	addr = buf;
	pos = 0;
	pack_bits(&addr, &pos, crc, UBIFS_LPT_CRC_BITS);
}

/**
 * ubifs_add_lpt_dirt - add dirty space to LPT LEB properties.
 * @c: UBIFS file-system description object
 * @lnum: LEB number to which to add dirty space
 * @dirty: amount of dirty space to add
 */
void ubifs_add_lpt_dirt(struct ubifs_info *c, int lnum, int dirty)
{
	if (!dirty || !lnum)
		return;
	dbg_lp("LEB %d add %d to %d",
	       lnum, dirty, c->ltab[lnum - c->lpt_first].dirty);
	ubifs_assert(lnum >= c->lpt_first && lnum <= c->lpt_last);
	c->ltab[lnum - c->lpt_first].dirty += dirty;
}

/**
 * set_ltab - set LPT LEB properties.
 * @c: UBIFS file-system description object
 * @lnum: LEB number
 * @free: amount of free space
 * @dirty: amount of dirty space
 */
static void set_ltab(struct ubifs_info *c, int lnum, int free, int dirty)
{
	dbg_lp("LEB %d free %d dirty %d to %d %d",
	       lnum, c->ltab[lnum - c->lpt_first].free,
	       c->ltab[lnum - c->lpt_first].dirty, free, dirty);
	ubifs_assert(lnum >= c->lpt_first && lnum <= c->lpt_last);
	c->ltab[lnum - c->lpt_first].free = free;
	c->ltab[lnum - c->lpt_first].dirty = dirty;
}

/**
 * ubifs_add_nnode_dirt - add dirty space to LPT LEB properties.
 * @c: UBIFS file-system description object
 * @nnode: nnode for which to add dirt
 */
void ubifs_add_nnode_dirt(struct ubifs_info *c, struct ubifs_nnode *nnode)
{
	struct ubifs_nnode *np = nnode->parent;

	if (np)
		ubifs_add_lpt_dirt(c, np->nbranch[nnode->iip].lnum,
				   c->nnode_sz);
	else {
		ubifs_add_lpt_dirt(c, c->lpt_lnum, c->nnode_sz);
		if (!(c->lpt_drty_flgs & LTAB_DIRTY)) {
			c->lpt_drty_flgs |= LTAB_DIRTY;
			ubifs_add_lpt_dirt(c, c->ltab_lnum, c->ltab_sz);
		}
	}
}

/**
 * add_pnode_dirt - add dirty space to LPT LEB properties.
 * @c: UBIFS file-system description object
 * @pnode: pnode for which to add dirt
 */
static void add_pnode_dirt(struct ubifs_info *c, struct ubifs_pnode *pnode)
{
	ubifs_add_lpt_dirt(c, pnode->parent->nbranch[pnode->iip].lnum,
			   c->pnode_sz);
}

/**
 * calc_nnode_num - calculate nnode number.
 * @row: the row in the tree (root is zero)
 * @col: the column in the row (leftmost is zero)
 *
 * The nnode number is a number that uniquely identifies a nnode and can be used
 * easily to traverse the tree from the root to that nnode.
 *
 * This function calculates and returns the nnode number for the nnode at @row
 * and @col.
 */
static int calc_nnode_num(int row, int col)
{
	int num, bits;

	num = 1;
	while (row--) {
		bits = (col & (UBIFS_LPT_FANOUT - 1));
		col >>= UBIFS_LPT_FANOUT_SHIFT;
		num <<= UBIFS_LPT_FANOUT_SHIFT;
		num |= bits;
	}
	return num;
}

/**
 * calc_nnode_num_from_parent - calculate nnode number.
 * @c: UBIFS file-system description object
 * @parent: parent nnode
 * @iip: index in parent
 *
 * The nnode number is a number that uniquely identifies a nnode and can be used
 * easily to traverse the tree from the root to that nnode.
 *
 * This function calculates and returns the nnode number based on the parent's
 * nnode number and the index in parent.
 */
static int calc_nnode_num_from_parent(struct ubifs_info *c,
				      struct ubifs_nnode *parent, int iip)
{
	int num, shft;

	if (!parent)
		return 1;
	shft = (c->lpt_hght - parent->level) * UBIFS_LPT_FANOUT_SHIFT;
	num = parent->num ^ (1 << shft);
	num |= (UBIFS_LPT_FANOUT + iip) << shft;
	return num;
}

/**
 * calc_pnode_num_from_parent - calculate pnode number.
 * @c: UBIFS file-system description object
 * @parent: parent nnode
 * @iip: index in parent
 *
 * The pnode number is a number that uniquely identifies a pnode and can be used
 * easily to traverse the tree from the root to that pnode.
 *
 * This function calculates and returns the pnode number based on the parent's
 * nnode number and the index in parent.
 */
static int calc_pnode_num_from_parent(struct ubifs_info *c,
				      struct ubifs_nnode *parent, int iip)
{
	int i, n = c->lpt_hght - 1, pnum = parent->num, num = 0;

	for (i = 0; i < n; i++) {
		num <<= UBIFS_LPT_FANOUT_SHIFT;
		num |= pnum & (UBIFS_LPT_FANOUT - 1);
		pnum >>= UBIFS_LPT_FANOUT_SHIFT;
	}
	num <<= UBIFS_LPT_FANOUT_SHIFT;
	num |= iip;
	return num;
}

/**
 * ubifs_create_dflt_lpt - create default LPT.
 * @c: UBIFS file-system description object
 * @main_lebs: number of main area LEBs is passed and returned here
 * @lpt_first: LEB number of first LPT LEB
 * @lpt_lebs: number of LEBs for LPT is passed and returned here
 * @big_lpt: use big LPT model is passed and returned here
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_create_dflt_lpt(struct ubifs_info *c, int *main_lebs, int lpt_first,
			  int *lpt_lebs, int *big_lpt)
{
	int lnum, err = 0, node_sz, iopos, i, j, cnt, len, alen, row;
	int blnum, boffs, bsz, bcnt;
	struct ubifs_pnode *pnode = NULL;
	struct ubifs_nnode *nnode = NULL;
	void *buf = NULL, *p;
	struct ubifs_lpt_lprops *ltab = NULL;
	int *lsave = NULL;

	err = calc_dflt_lpt_geom(c, main_lebs, big_lpt);
	if (err)
		return err;
	*lpt_lebs = c->lpt_lebs;

	/* Needed by 'ubifs_pack_nnode()' and 'set_ltab()' */
	c->lpt_first = lpt_first;
	/* Needed by 'set_ltab()' */
	c->lpt_last = lpt_first + c->lpt_lebs - 1;
	/* Needed by 'ubifs_pack_lsave()' */
	c->main_first = c->leb_cnt - *main_lebs;

	lsave = kmalloc(sizeof(int) * c->lsave_cnt, GFP_KERNEL);
	pnode = kzalloc(sizeof(struct ubifs_pnode), GFP_KERNEL);
	nnode = kzalloc(sizeof(struct ubifs_nnode), GFP_KERNEL);
	buf = vmalloc(c->leb_size);
	ltab = vmalloc(sizeof(struct ubifs_lpt_lprops) * c->lpt_lebs);
	if (!pnode || !nnode || !buf || !ltab || !lsave) {
		err = -ENOMEM;
		goto out;
	}

	ubifs_assert(!c->ltab);
	c->ltab = ltab; /* Needed by set_ltab */

	/* Initialize LPT's own lprops */
	for (i = 0; i < c->lpt_lebs; i++) {
		ltab[i].free = c->leb_size;
		ltab[i].dirty = 0;
		ltab[i].tgc = 0;
		ltab[i].cmt = 0;
	}

	lnum = lpt_first;
	p = buf;
	/* Number of leaf nodes (pnodes) */
	cnt = c->pnode_cnt;

	/*
	 * The first pnode contains the LEB properties for the LEBs that contain
	 * the root inode node and the root index node of the index tree.
	 */
	node_sz = ALIGN(ubifs_idx_node_sz(c, 1), 8);
	iopos = ALIGN(node_sz, c->min_io_size);
	pnode->lprops[0].free = c->leb_size - iopos;
	pnode->lprops[0].dirty = iopos - node_sz;
	pnode->lprops[0].flags = LPROPS_INDEX;

	node_sz = UBIFS_INO_NODE_SZ;
	iopos = ALIGN(node_sz, c->min_io_size);
	pnode->lprops[1].free = c->leb_size - iopos;
	pnode->lprops[1].dirty = iopos - node_sz;

	for (i = 2; i < UBIFS_LPT_FANOUT; i++)
		pnode->lprops[i].free = c->leb_size;

	/* Add first pnode */
	ubifs_pack_pnode(c, p, pnode);
	p += c->pnode_sz;
	len = c->pnode_sz;
	pnode->num += 1;

	/* Reset pnode values for remaining pnodes */
	pnode->lprops[0].free = c->leb_size;
	pnode->lprops[0].dirty = 0;
	pnode->lprops[0].flags = 0;

	pnode->lprops[1].free = c->leb_size;
	pnode->lprops[1].dirty = 0;

	/*
	 * To calculate the internal node branches, we keep information about
	 * the level below.
	 */
	blnum = lnum; /* LEB number of level below */
	boffs = 0; /* Offset of level below */
	bcnt = cnt; /* Number of nodes in level below */
	bsz = c->pnode_sz; /* Size of nodes in level below */

	/* Add all remaining pnodes */
	for (i = 1; i < cnt; i++) {
		if (len + c->pnode_sz > c->leb_size) {
			alen = ALIGN(len, c->min_io_size);
			set_ltab(c, lnum, c->leb_size - alen, alen - len);
			memset(p, 0xff, alen - len);
			err = ubi_leb_change(c->ubi, lnum++, buf, alen,
					     UBI_SHORTTERM);
			if (err)
				goto out;
			p = buf;
			len = 0;
		}
		ubifs_pack_pnode(c, p, pnode);
		p += c->pnode_sz;
		len += c->pnode_sz;
		/*
		 * pnodes are simply numbered left to right starting at zero,
		 * which means the pnode number can be used easily to traverse
		 * down the tree to the corresponding pnode.
		 */
		pnode->num += 1;
	}

	row = 0;
	for (i = UBIFS_LPT_FANOUT; cnt > i; i <<= UBIFS_LPT_FANOUT_SHIFT)
		row += 1;
	/* Add all nnodes, one level at a time */
	while (1) {
		/* Number of internal nodes (nnodes) at next level */
		cnt = DIV_ROUND_UP(cnt, UBIFS_LPT_FANOUT);
		for (i = 0; i < cnt; i++) {
			if (len + c->nnode_sz > c->leb_size) {
				alen = ALIGN(len, c->min_io_size);
				set_ltab(c, lnum, c->leb_size - alen,
					    alen - len);
				memset(p, 0xff, alen - len);
				err = ubi_leb_change(c->ubi, lnum++, buf, alen,
						     UBI_SHORTTERM);
				if (err)
					goto out;
				p = buf;
				len = 0;
			}
			/* Only 1 nnode at this level, so it is the root */
			if (cnt == 1) {
				c->lpt_lnum = lnum;
				c->lpt_offs = len;
			}
			/* Set branches to the level below */
			for (j = 0; j < UBIFS_LPT_FANOUT; j++) {
				if (bcnt) {
					if (boffs + bsz > c->leb_size) {
						blnum += 1;
						boffs = 0;
					}
					nnode->nbranch[j].lnum = blnum;
					nnode->nbranch[j].offs = boffs;
					boffs += bsz;
					bcnt--;
				} else {
					nnode->nbranch[j].lnum = 0;
					nnode->nbranch[j].offs = 0;
				}
			}
			nnode->num = calc_nnode_num(row, i);
			ubifs_pack_nnode(c, p, nnode);
			p += c->nnode_sz;
			len += c->nnode_sz;
		}
		/* Only 1 nnode at this level, so it is the root */
		if (cnt == 1)
			break;
		/* Update the information about the level below */
		bcnt = cnt;
		bsz = c->nnode_sz;
		row -= 1;
	}

	if (*big_lpt) {
		/* Need to add LPT's save table */
		if (len + c->lsave_sz > c->leb_size) {
			alen = ALIGN(len, c->min_io_size);
			set_ltab(c, lnum, c->leb_size - alen, alen - len);
			memset(p, 0xff, alen - len);
			err = ubi_leb_change(c->ubi, lnum++, buf, alen,
					     UBI_SHORTTERM);
			if (err)
				goto out;
			p = buf;
			len = 0;
		}

		c->lsave_lnum = lnum;
		c->lsave_offs = len;

		for (i = 0; i < c->lsave_cnt && i < *main_lebs; i++)
			lsave[i] = c->main_first + i;
		for (; i < c->lsave_cnt; i++)
			lsave[i] = c->main_first;

		ubifs_pack_lsave(c, p, lsave);
		p += c->lsave_sz;
		len += c->lsave_sz;
	}

	/* Need to add LPT's own LEB properties table */
	if (len + c->ltab_sz > c->leb_size) {
		alen = ALIGN(len, c->min_io_size);
		set_ltab(c, lnum, c->leb_size - alen, alen - len);
		memset(p, 0xff, alen - len);
		err = ubi_leb_change(c->ubi, lnum++, buf, alen, UBI_SHORTTERM);
		if (err)
			goto out;
		p = buf;
		len = 0;
	}

	c->ltab_lnum = lnum;
	c->ltab_offs = len;

	/* Update ltab before packing it */
	len += c->ltab_sz;
	alen = ALIGN(len, c->min_io_size);
	set_ltab(c, lnum, c->leb_size - alen, alen - len);

	ubifs_pack_ltab(c, p, ltab);
	p += c->ltab_sz;

	/* Write remaining buffer */
	memset(p, 0xff, alen - len);
	err = ubi_leb_change(c->ubi, lnum, buf, alen, UBI_SHORTTERM);
	if (err)
		goto out;

	c->nhead_lnum = lnum;
	c->nhead_offs = ALIGN(len, c->min_io_size);

	dbg_lp("space_bits %d", c->space_bits);
	dbg_lp("lpt_lnum_bits %d", c->lpt_lnum_bits);
	dbg_lp("lpt_offs_bits %d", c->lpt_offs_bits);
	dbg_lp("lpt_spc_bits %d", c->lpt_spc_bits);
	dbg_lp("pcnt_bits %d", c->pcnt_bits);
	dbg_lp("lnum_bits %d", c->lnum_bits);
	dbg_lp("pnode_sz %d", c->pnode_sz);
	dbg_lp("nnode_sz %d", c->nnode_sz);
	dbg_lp("ltab_sz %d", c->ltab_sz);
	dbg_lp("lsave_sz %d", c->lsave_sz);
	dbg_lp("lsave_cnt %d", c->lsave_cnt);
	dbg_lp("lpt_hght %d", c->lpt_hght);
	dbg_lp("big_lpt %d", c->big_lpt);
	dbg_lp("LPT root is at %d:%d", c->lpt_lnum, c->lpt_offs);
	dbg_lp("LPT head is at %d:%d", c->nhead_lnum, c->nhead_offs);
	dbg_lp("LPT ltab is at %d:%d", c->ltab_lnum, c->ltab_offs);
	if (c->big_lpt)
		dbg_lp("LPT lsave is at %d:%d", c->lsave_lnum, c->lsave_offs);
out:
	c->ltab = NULL;
	kfree(lsave);
	vfree(ltab);
	vfree(buf);
	kfree(nnode);
	kfree(pnode);
	return err;
}

/**
 * update_cats - add LEB properties of a pnode to LEB category lists and heaps.
 * @c: UBIFS file-system description object
 * @pnode: pnode
 *
 * When a pnode is loaded into memory, the LEB properties it contains are added,
 * by this function, to the LEB category lists and heaps.
 */
static void update_cats(struct ubifs_info *c, struct ubifs_pnode *pnode)
{
	int i;

	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		int cat = pnode->lprops[i].flags & LPROPS_CAT_MASK;
		int lnum = pnode->lprops[i].lnum;

		if (!lnum)
			return;
		ubifs_add_to_cat(c, &pnode->lprops[i], cat);
	}
}

/**
 * replace_cats - add LEB properties of a pnode to LEB category lists and heaps.
 * @c: UBIFS file-system description object
 * @old_pnode: pnode copied
 * @new_pnode: pnode copy
 *
 * During commit it is sometimes necessary to copy a pnode
 * (see dirty_cow_pnode).  When that happens, references in
 * category lists and heaps must be replaced.  This function does that.
 */
static void replace_cats(struct ubifs_info *c, struct ubifs_pnode *old_pnode,
			 struct ubifs_pnode *new_pnode)
{
	int i;

	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		if (!new_pnode->lprops[i].lnum)
			return;
		ubifs_replace_cat(c, &old_pnode->lprops[i],
				  &new_pnode->lprops[i]);
	}
}

/**
 * check_lpt_crc - check LPT node crc is correct.
 * @c: UBIFS file-system description object
 * @buf: buffer containing node
 * @len: length of node
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int check_lpt_crc(void *buf, int len)
{
	int pos = 0;
	uint8_t *addr = buf;
	uint16_t crc, calc_crc;

	crc = ubifs_unpack_bits(&addr, &pos, UBIFS_LPT_CRC_BITS);
	calc_crc = crc16(-1, buf + UBIFS_LPT_CRC_BYTES,
			 len - UBIFS_LPT_CRC_BYTES);
	if (crc != calc_crc) {
		ubifs_err("invalid crc in LPT node: crc %hx calc %hx", crc,
			  calc_crc);
		dbg_dump_stack();
		return -EINVAL;
	}
	return 0;
}

/**
 * check_lpt_type - check LPT node type is correct.
 * @c: UBIFS file-system description object
 * @addr: address of type bit field is passed and returned updated here
 * @pos: position of type bit field is passed and returned updated here
 * @type: expected type
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int check_lpt_type(uint8_t **addr, int *pos, int type)
{
	int node_type;

	node_type = ubifs_unpack_bits(addr, pos, UBIFS_LPT_TYPE_BITS);
	if (node_type != type) {
		ubifs_err("invalid type (%d) in LPT node type %d", node_type,
			  type);
		dbg_dump_stack();
		return -EINVAL;
	}
	return 0;
}

/**
 * unpack_pnode - unpack a pnode.
 * @c: UBIFS file-system description object
 * @buf: buffer containing packed pnode to unpack
 * @pnode: pnode structure to fill
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int unpack_pnode(struct ubifs_info *c, void *buf,
			struct ubifs_pnode *pnode)
{
	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
	int i, pos = 0, err;

	err = check_lpt_type(&addr, &pos, UBIFS_LPT_PNODE);
	if (err)
		return err;
	if (c->big_lpt)
		pnode->num = ubifs_unpack_bits(&addr, &pos, c->pcnt_bits);
	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		struct ubifs_lprops * const lprops = &pnode->lprops[i];

		lprops->free = ubifs_unpack_bits(&addr, &pos, c->space_bits);
		lprops->free <<= 3;
		lprops->dirty = ubifs_unpack_bits(&addr, &pos, c->space_bits);
		lprops->dirty <<= 3;

		if (ubifs_unpack_bits(&addr, &pos, 1))
			lprops->flags = LPROPS_INDEX;
		else
			lprops->flags = 0;
		lprops->flags |= ubifs_categorize_lprops(c, lprops);
	}
	err = check_lpt_crc(buf, c->pnode_sz);
	return err;
}

/**
 * unpack_nnode - unpack a nnode.
 * @c: UBIFS file-system description object
 * @buf: buffer containing packed nnode to unpack
 * @nnode: nnode structure to fill
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int unpack_nnode(struct ubifs_info *c, void *buf,
			struct ubifs_nnode *nnode)
{
	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
	int i, pos = 0, err;

	err = check_lpt_type(&addr, &pos, UBIFS_LPT_NNODE);
	if (err)
		return err;
	if (c->big_lpt)
		nnode->num = ubifs_unpack_bits(&addr, &pos, c->pcnt_bits);
	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		int lnum;

		lnum = ubifs_unpack_bits(&addr, &pos, c->lpt_lnum_bits) +
		       c->lpt_first;
		if (lnum == c->lpt_last + 1)
			lnum = 0;
		nnode->nbranch[i].lnum = lnum;
		nnode->nbranch[i].offs = ubifs_unpack_bits(&addr, &pos,
						     c->lpt_offs_bits);
	}
	err = check_lpt_crc(buf, c->nnode_sz);
	return err;
}

/**
 * unpack_ltab - unpack the LPT's own lprops table.
 * @c: UBIFS file-system description object
 * @buf: buffer from which to unpack
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int unpack_ltab(struct ubifs_info *c, void *buf)
{
	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
	int i, pos = 0, err;

	err = check_lpt_type(&addr, &pos, UBIFS_LPT_LTAB);
	if (err)
		return err;
	for (i = 0; i < c->lpt_lebs; i++) {
		int free = ubifs_unpack_bits(&addr, &pos, c->lpt_spc_bits);
		int dirty = ubifs_unpack_bits(&addr, &pos, c->lpt_spc_bits);

		if (free < 0 || free > c->leb_size || dirty < 0 ||
		    dirty > c->leb_size || free + dirty > c->leb_size)
			return -EINVAL;

		c->ltab[i].free = free;
		c->ltab[i].dirty = dirty;
		c->ltab[i].tgc = 0;
		c->ltab[i].cmt = 0;
	}
	err = check_lpt_crc(buf, c->ltab_sz);
	return err;
}

/**
 * unpack_lsave - unpack the LPT's save table.
 * @c: UBIFS file-system description object
 * @buf: buffer from which to unpack
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int unpack_lsave(struct ubifs_info *c, void *buf)
{
	uint8_t *addr = buf + UBIFS_LPT_CRC_BYTES;
	int i, pos = 0, err;

	err = check_lpt_type(&addr, &pos, UBIFS_LPT_LSAVE);
	if (err)
		return err;
	for (i = 0; i < c->lsave_cnt; i++) {
		int lnum = ubifs_unpack_bits(&addr, &pos, c->lnum_bits);

		if (lnum < c->main_first || lnum >= c->leb_cnt)
			return -EINVAL;
		c->lsave[i] = lnum;
	}
	err = check_lpt_crc(buf, c->lsave_sz);
	return err;
}

/**
 * validate_nnode - validate a nnode.
 * @c: UBIFS file-system description object
 * @nnode: nnode to validate
 * @parent: parent nnode (or NULL for the root nnode)
 * @iip: index in parent
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int validate_nnode(struct ubifs_info *c, struct ubifs_nnode *nnode,
			  struct ubifs_nnode *parent, int iip)
{
	int i, lvl, max_offs;

	if (c->big_lpt) {
		int num = calc_nnode_num_from_parent(c, parent, iip);

		if (nnode->num != num)
			return -EINVAL;
	}
	lvl = parent ? parent->level - 1 : c->lpt_hght;
	if (lvl < 1)
		return -EINVAL;
	if (lvl == 1)
		max_offs = c->leb_size - c->pnode_sz;
	else
		max_offs = c->leb_size - c->nnode_sz;
	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		int lnum = nnode->nbranch[i].lnum;
		int offs = nnode->nbranch[i].offs;

		if (lnum == 0) {
			if (offs != 0)
				return -EINVAL;
			continue;
		}
		if (lnum < c->lpt_first || lnum > c->lpt_last)
			return -EINVAL;
		if (offs < 0 || offs > max_offs)
			return -EINVAL;
	}
	return 0;
}

/**
 * validate_pnode - validate a pnode.
 * @c: UBIFS file-system description object
 * @pnode: pnode to validate
 * @parent: parent nnode
 * @iip: index in parent
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int validate_pnode(struct ubifs_info *c, struct ubifs_pnode *pnode,
			  struct ubifs_nnode *parent, int iip)
{
	int i;

	if (c->big_lpt) {
		int num = calc_pnode_num_from_parent(c, parent, iip);

		if (pnode->num != num)
			return -EINVAL;
	}
	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		int free = pnode->lprops[i].free;
		int dirty = pnode->lprops[i].dirty;

		if (free < 0 || free > c->leb_size || free % c->min_io_size ||
		    (free & 7))
			return -EINVAL;
		if (dirty < 0 || dirty > c->leb_size || (dirty & 7))
			return -EINVAL;
		if (dirty + free > c->leb_size)
			return -EINVAL;
	}
	return 0;
}

/**
 * set_pnode_lnum - set LEB numbers on a pnode.
 * @c: UBIFS file-system description object
 * @pnode: pnode to update
 *
 * This function calculates the LEB numbers for the LEB properties it contains
 * based on the pnode number.
 */
static void set_pnode_lnum(struct ubifs_info *c, struct ubifs_pnode *pnode)
{
	int i, lnum;

	lnum = (pnode->num << UBIFS_LPT_FANOUT_SHIFT) + c->main_first;
	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		if (lnum >= c->leb_cnt)
			return;
		pnode->lprops[i].lnum = lnum++;
	}
}

/**
 * ubifs_read_nnode - read a nnode from flash and link it to the tree in memory.
 * @c: UBIFS file-system description object
 * @parent: parent nnode (or NULL for the root)
 * @iip: index in parent
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_read_nnode(struct ubifs_info *c, struct ubifs_nnode *parent, int iip)
{
	struct ubifs_nbranch *branch = NULL;
	struct ubifs_nnode *nnode = NULL;
	void *buf = c->lpt_nod_buf;
	int err, lnum, offs;

	if (parent) {
		branch = &parent->nbranch[iip];
		lnum = branch->lnum;
		offs = branch->offs;
	} else {
		lnum = c->lpt_lnum;
		offs = c->lpt_offs;
	}
	nnode = kzalloc(sizeof(struct ubifs_nnode), GFP_NOFS);
	if (!nnode) {
		err = -ENOMEM;
		goto out;
	}
	if (lnum == 0) {
		/*
		 * This nnode was not written which just means that the LEB
		 * properties in the subtree below it describe empty LEBs. We
		 * make the nnode as though we had read it, which in fact means
		 * doing almost nothing.
		 */
		if (c->big_lpt)
			nnode->num = calc_nnode_num_from_parent(c, parent, iip);
	} else {
		err = ubi_read(c->ubi, lnum, buf, offs, c->nnode_sz);
		if (err)
			goto out;
		err = unpack_nnode(c, buf, nnode);
		if (err)
			goto out;
	}
	err = validate_nnode(c, nnode, parent, iip);
	if (err)
		goto out;
	if (!c->big_lpt)
		nnode->num = calc_nnode_num_from_parent(c, parent, iip);
	if (parent) {
		branch->nnode = nnode;
		nnode->level = parent->level - 1;
	} else {
		c->nroot = nnode;
		nnode->level = c->lpt_hght;
	}
	nnode->parent = parent;
	nnode->iip = iip;
	return 0;

out:
	ubifs_err("error %d reading nnode at %d:%d", err, lnum, offs);
	kfree(nnode);
	return err;
}

/**
 * read_pnode - read a pnode from flash and link it to the tree in memory.
 * @c: UBIFS file-system description object
 * @parent: parent nnode
 * @iip: index in parent
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int read_pnode(struct ubifs_info *c, struct ubifs_nnode *parent, int iip)
{
	struct ubifs_nbranch *branch;
	struct ubifs_pnode *pnode = NULL;
	void *buf = c->lpt_nod_buf;
	int err, lnum, offs;

	branch = &parent->nbranch[iip];
	lnum = branch->lnum;
	offs = branch->offs;
	pnode = kzalloc(sizeof(struct ubifs_pnode), GFP_NOFS);
	if (!pnode) {
		err = -ENOMEM;
		goto out;
	}
	if (lnum == 0) {
		/*
		 * This pnode was not written which just means that the LEB
		 * properties in it describe empty LEBs. We make the pnode as
		 * though we had read it.
		 */
		int i;

		if (c->big_lpt)
			pnode->num = calc_pnode_num_from_parent(c, parent, iip);
		for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
			struct ubifs_lprops * const lprops = &pnode->lprops[i];

			lprops->free = c->leb_size;
			lprops->flags = ubifs_categorize_lprops(c, lprops);
		}
	} else {
		err = ubi_read(c->ubi, lnum, buf, offs, c->pnode_sz);
		if (err)
			goto out;
		err = unpack_pnode(c, buf, pnode);
		if (err)
			goto out;
	}
	err = validate_pnode(c, pnode, parent, iip);
	if (err)
		goto out;
	if (!c->big_lpt)
		pnode->num = calc_pnode_num_from_parent(c, parent, iip);
	branch->pnode = pnode;
	pnode->parent = parent;
	pnode->iip = iip;
	set_pnode_lnum(c, pnode);
	c->pnodes_have += 1;
	return 0;

out:
	ubifs_err("error %d reading pnode at %d:%d", err, lnum, offs);
	dbg_dump_pnode(c, pnode, parent, iip);
	dbg_msg("calc num: %d", calc_pnode_num_from_parent(c, parent, iip));
	kfree(pnode);
	return err;
}

/**
 * read_ltab - read LPT's own lprops table.
 * @c: UBIFS file-system description object
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int read_ltab(struct ubifs_info *c)
{
	int err;
	void *buf;

	buf = vmalloc(c->ltab_sz);
	if (!buf)
		return -ENOMEM;
	err = ubi_read(c->ubi, c->ltab_lnum, buf, c->ltab_offs, c->ltab_sz);
	if (err)
		goto out;
	err = unpack_ltab(c, buf);
out:
	vfree(buf);
	return err;
}

/**
 * read_lsave - read LPT's save table.
 * @c: UBIFS file-system description object
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int read_lsave(struct ubifs_info *c)
{
	int err, i;
	void *buf;

	buf = vmalloc(c->lsave_sz);
	if (!buf)
		return -ENOMEM;
	err = ubi_read(c->ubi, c->lsave_lnum, buf, c->lsave_offs, c->lsave_sz);
	if (err)
		goto out;
	err = unpack_lsave(c, buf);
	if (err)
		goto out;
	for (i = 0; i < c->lsave_cnt; i++) {
		int lnum = c->lsave[i];

		/*
		 * Due to automatic resizing, the values in the lsave table
		 * could be beyond the volume size - just ignore them.
		 */
		if (lnum >= c->leb_cnt)
			continue;
		ubifs_lpt_lookup(c, lnum);
	}
out:
	vfree(buf);
	return err;
}

/**
 * ubifs_get_nnode - get a nnode.
 * @c: UBIFS file-system description object
 * @parent: parent nnode (or NULL for the root)
 * @iip: index in parent
 *
 * This function returns a pointer to the nnode on success or a negative error
 * code on failure.
 */
struct ubifs_nnode *ubifs_get_nnode(struct ubifs_info *c,
				    struct ubifs_nnode *parent, int iip)
{
	struct ubifs_nbranch *branch;
	struct ubifs_nnode *nnode;
	int err;

	branch = &parent->nbranch[iip];
	nnode = branch->nnode;
	if (nnode)
		return nnode;
	err = ubifs_read_nnode(c, parent, iip);
	if (err)
		return ERR_PTR(err);
	return branch->nnode;
}

/**
 * ubifs_get_pnode - get a pnode.
 * @c: UBIFS file-system description object
 * @parent: parent nnode
 * @iip: index in parent
 *
 * This function returns a pointer to the pnode on success or a negative error
 * code on failure.
 */
struct ubifs_pnode *ubifs_get_pnode(struct ubifs_info *c,
				    struct ubifs_nnode *parent, int iip)
{
	struct ubifs_nbranch *branch;
	struct ubifs_pnode *pnode;
	int err;

	branch = &parent->nbranch[iip];
	pnode = branch->pnode;
	if (pnode)
		return pnode;
	err = read_pnode(c, parent, iip);
	if (err)
		return ERR_PTR(err);
	update_cats(c, branch->pnode);
	return branch->pnode;
}

/**
 * ubifs_lpt_lookup - lookup LEB properties in the LPT.
 * @c: UBIFS file-system description object
 * @lnum: LEB number to lookup
 *
 * This function returns a pointer to the LEB properties on success or a
 * negative error code on failure.
 */
struct ubifs_lprops *ubifs_lpt_lookup(struct ubifs_info *c, int lnum)
{
	int err, i, h, iip, shft;
	struct ubifs_nnode *nnode;
	struct ubifs_pnode *pnode;

	if (!c->nroot) {
		err = ubifs_read_nnode(c, NULL, 0);
		if (err)
			return ERR_PTR(err);
	}
	nnode = c->nroot;
	i = lnum - c->main_first;
	shft = c->lpt_hght * UBIFS_LPT_FANOUT_SHIFT;
	for (h = 1; h < c->lpt_hght; h++) {
		iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
		shft -= UBIFS_LPT_FANOUT_SHIFT;
		nnode = ubifs_get_nnode(c, nnode, iip);
		if (IS_ERR(nnode))
			return ERR_PTR(PTR_ERR(nnode));
	}
	iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
	shft -= UBIFS_LPT_FANOUT_SHIFT;
	pnode = ubifs_get_pnode(c, nnode, iip);
	if (IS_ERR(pnode))
		return ERR_PTR(PTR_ERR(pnode));
	iip = (i & (UBIFS_LPT_FANOUT - 1));
	dbg_lp("LEB %d, free %d, dirty %d, flags %d", lnum,
	       pnode->lprops[iip].free, pnode->lprops[iip].dirty,
	       pnode->lprops[iip].flags);
	return &pnode->lprops[iip];
}

/**
 * dirty_cow_nnode - ensure a nnode is not being committed.
 * @c: UBIFS file-system description object
 * @nnode: nnode to check
 *
 * Returns dirtied nnode on success or negative error code on failure.
 */
static struct ubifs_nnode *dirty_cow_nnode(struct ubifs_info *c,
					   struct ubifs_nnode *nnode)
{
	struct ubifs_nnode *n;
	int i;

	if (!test_bit(COW_CNODE, &nnode->flags)) {
		/* nnode is not being committed */
		if (!test_and_set_bit(DIRTY_CNODE, &nnode->flags)) {
			c->dirty_nn_cnt += 1;
			ubifs_add_nnode_dirt(c, nnode);
		}
		return nnode;
	}

	/* nnode is being committed, so copy it */
	n = kmalloc(sizeof(struct ubifs_nnode), GFP_NOFS);
	if (unlikely(!n))
		return ERR_PTR(-ENOMEM);

	memcpy(n, nnode, sizeof(struct ubifs_nnode));
	n->cnext = NULL;
	__set_bit(DIRTY_CNODE, &n->flags);
	__clear_bit(COW_CNODE, &n->flags);

	/* The children now have new parent */
	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		struct ubifs_nbranch *branch = &n->nbranch[i];

		if (branch->cnode)
			branch->cnode->parent = n;
	}

	ubifs_assert(!test_bit(OBSOLETE_CNODE, &nnode->flags));
	__set_bit(OBSOLETE_CNODE, &nnode->flags);

	c->dirty_nn_cnt += 1;
	ubifs_add_nnode_dirt(c, nnode);
	if (nnode->parent)
		nnode->parent->nbranch[n->iip].nnode = n;
	else
		c->nroot = n;
	return n;
}

/**
 * dirty_cow_pnode - ensure a pnode is not being committed.
 * @c: UBIFS file-system description object
 * @pnode: pnode to check
 *
 * Returns dirtied pnode on success or negative error code on failure.
 */
static struct ubifs_pnode *dirty_cow_pnode(struct ubifs_info *c,
					   struct ubifs_pnode *pnode)
{
	struct ubifs_pnode *p;

	if (!test_bit(COW_CNODE, &pnode->flags)) {
		/* pnode is not being committed */
		if (!test_and_set_bit(DIRTY_CNODE, &pnode->flags)) {
			c->dirty_pn_cnt += 1;
			add_pnode_dirt(c, pnode);
		}
		return pnode;
	}

	/* pnode is being committed, so copy it */
	p = kmalloc(sizeof(struct ubifs_pnode), GFP_NOFS);
	if (unlikely(!p))
		return ERR_PTR(-ENOMEM);

	memcpy(p, pnode, sizeof(struct ubifs_pnode));
	p->cnext = NULL;
	__set_bit(DIRTY_CNODE, &p->flags);
	__clear_bit(COW_CNODE, &p->flags);
	replace_cats(c, pnode, p);

	ubifs_assert(!test_bit(OBSOLETE_CNODE, &pnode->flags));
	__set_bit(OBSOLETE_CNODE, &pnode->flags);

	c->dirty_pn_cnt += 1;
	add_pnode_dirt(c, pnode);
	pnode->parent->nbranch[p->iip].pnode = p;
	return p;
}

/**
 * ubifs_lpt_lookup_dirty - lookup LEB properties in the LPT.
 * @c: UBIFS file-system description object
 * @lnum: LEB number to lookup
 *
 * This function returns a pointer to the LEB properties on success or a
 * negative error code on failure.
 */
struct ubifs_lprops *ubifs_lpt_lookup_dirty(struct ubifs_info *c, int lnum)
{
	int err, i, h, iip, shft;
	struct ubifs_nnode *nnode;
	struct ubifs_pnode *pnode;

	if (!c->nroot) {
		err = ubifs_read_nnode(c, NULL, 0);
		if (err)
			return ERR_PTR(err);
	}
	nnode = c->nroot;
	nnode = dirty_cow_nnode(c, nnode);
	if (IS_ERR(nnode))
		return ERR_PTR(PTR_ERR(nnode));
	i = lnum - c->main_first;
	shft = c->lpt_hght * UBIFS_LPT_FANOUT_SHIFT;
	for (h = 1; h < c->lpt_hght; h++) {
		iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
		shft -= UBIFS_LPT_FANOUT_SHIFT;
		nnode = ubifs_get_nnode(c, nnode, iip);
		if (IS_ERR(nnode))
			return ERR_PTR(PTR_ERR(nnode));
		nnode = dirty_cow_nnode(c, nnode);
		if (IS_ERR(nnode))
			return ERR_PTR(PTR_ERR(nnode));
	}
	iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
	shft -= UBIFS_LPT_FANOUT_SHIFT;
	pnode = ubifs_get_pnode(c, nnode, iip);
	if (IS_ERR(pnode))
		return ERR_PTR(PTR_ERR(pnode));
	pnode = dirty_cow_pnode(c, pnode);
	if (IS_ERR(pnode))
		return ERR_PTR(PTR_ERR(pnode));
	iip = (i & (UBIFS_LPT_FANOUT - 1));
	dbg_lp("LEB %d, free %d, dirty %d, flags %d", lnum,
	       pnode->lprops[iip].free, pnode->lprops[iip].dirty,
	       pnode->lprops[iip].flags);
	ubifs_assert(test_bit(DIRTY_CNODE, &pnode->flags));
	return &pnode->lprops[iip];
}

/**
 * lpt_init_rd - initialize the LPT for reading.
 * @c: UBIFS file-system description object
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int lpt_init_rd(struct ubifs_info *c)
{
	int err, i;

	c->ltab = vmalloc(sizeof(struct ubifs_lpt_lprops) * c->lpt_lebs);
	if (!c->ltab)
		return -ENOMEM;

	i = max_t(int, c->nnode_sz, c->pnode_sz);
	c->lpt_nod_buf = kmalloc(i, GFP_KERNEL);
	if (!c->lpt_nod_buf)
		return -ENOMEM;

	for (i = 0; i < LPROPS_HEAP_CNT; i++) {
		c->lpt_heap[i].arr = kmalloc(sizeof(void *) * LPT_HEAP_SZ,
					     GFP_KERNEL);
		if (!c->lpt_heap[i].arr)
			return -ENOMEM;
		c->lpt_heap[i].cnt = 0;
		c->lpt_heap[i].max_cnt = LPT_HEAP_SZ;
	}

	c->dirty_idx.arr = kmalloc(sizeof(void *) * LPT_HEAP_SZ, GFP_KERNEL);
	if (!c->dirty_idx.arr)
		return -ENOMEM;
	c->dirty_idx.cnt = 0;
	c->dirty_idx.max_cnt = LPT_HEAP_SZ;

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

	dbg_lp("space_bits %d", c->space_bits);
	dbg_lp("lpt_lnum_bits %d", c->lpt_lnum_bits);
	dbg_lp("lpt_offs_bits %d", c->lpt_offs_bits);
	dbg_lp("lpt_spc_bits %d", c->lpt_spc_bits);
	dbg_lp("pcnt_bits %d", c->pcnt_bits);
	dbg_lp("lnum_bits %d", c->lnum_bits);
	dbg_lp("pnode_sz %d", c->pnode_sz);
	dbg_lp("nnode_sz %d", c->nnode_sz);
	dbg_lp("ltab_sz %d", c->ltab_sz);
	dbg_lp("lsave_sz %d", c->lsave_sz);
	dbg_lp("lsave_cnt %d", c->lsave_cnt);
	dbg_lp("lpt_hght %d", c->lpt_hght);
	dbg_lp("big_lpt %d", c->big_lpt);
	dbg_lp("LPT root is at %d:%d", c->lpt_lnum, c->lpt_offs);
	dbg_lp("LPT head is at %d:%d", c->nhead_lnum, c->nhead_offs);
	dbg_lp("LPT ltab is at %d:%d", c->ltab_lnum, c->ltab_offs);
	if (c->big_lpt)
		dbg_lp("LPT lsave is at %d:%d", c->lsave_lnum, c->lsave_offs);

	return 0;
}

/**
 * lpt_init_wr - initialize the LPT for writing.
 * @c: UBIFS file-system description object
 *
 * 'lpt_init_rd()' must have been called already.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int lpt_init_wr(struct ubifs_info *c)
{
	int err, i;

	c->ltab_cmt = vmalloc(sizeof(struct ubifs_lpt_lprops) * c->lpt_lebs);
	if (!c->ltab_cmt)
		return -ENOMEM;

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

	if (c->big_lpt) {
		c->lsave = kmalloc(sizeof(int) * c->lsave_cnt, GFP_NOFS);
		if (!c->lsave)
			return -ENOMEM;
		err = read_lsave(c);
		if (err)
			return err;
	}

	for (i = 0; i < c->lpt_lebs; i++)
		if (c->ltab[i].free == c->leb_size) {
			err = ubifs_leb_unmap(c, i + c->lpt_first);
			if (err)
				return err;
		}

	return 0;
}

/**
 * ubifs_lpt_init - initialize the LPT.
 * @c: UBIFS file-system description object
 * @rd: whether to initialize lpt for reading
 * @wr: whether to initialize lpt for writing
 *
 * For mounting 'rw', @rd and @wr are both true. For mounting 'ro', @rd is true
 * and @wr is false. For mounting from 'ro' to 'rw', @rd is false and @wr is
 * true.
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_lpt_init(struct ubifs_info *c, int rd, int wr)
{
	int err;

	if (rd) {
		err = lpt_init_rd(c);
		if (err)
			return err;
	}

	if (wr) {
		err = lpt_init_wr(c);
		if (err)
			return err;
	}

	return 0;
}

/**
 * struct lpt_scan_node - somewhere to put nodes while we scan LPT.
 * @nnode: where to keep a nnode
 * @pnode: where to keep a pnode
 * @cnode: where to keep a cnode
 * @in_tree: is the node in the tree in memory
 * @ptr.nnode: pointer to the nnode (if it is an nnode) which may be here or in
 * the tree
 * @ptr.pnode: ditto for pnode
 * @ptr.cnode: ditto for cnode
 */
struct lpt_scan_node {
	union {
		struct ubifs_nnode nnode;
		struct ubifs_pnode pnode;
		struct ubifs_cnode cnode;
	};
	int in_tree;
	union {
		struct ubifs_nnode *nnode;
		struct ubifs_pnode *pnode;
		struct ubifs_cnode *cnode;
	} ptr;
};

/**
 * scan_get_nnode - for the scan, get a nnode from either the tree or flash.
 * @c: the UBIFS file-system description object
 * @path: where to put the nnode
 * @parent: parent of the nnode
 * @iip: index in parent of the nnode
 *
 * This function returns a pointer to the nnode on success or a negative error
 * code on failure.
 */
static struct ubifs_nnode *scan_get_nnode(struct ubifs_info *c,
					  struct lpt_scan_node *path,
					  struct ubifs_nnode *parent, int iip)
{
	struct ubifs_nbranch *branch;
	struct ubifs_nnode *nnode;
	void *buf = c->lpt_nod_buf;
	int err;

	branch = &parent->nbranch[iip];
	nnode = branch->nnode;
	if (nnode) {
		path->in_tree = 1;
		path->ptr.nnode = nnode;
		return nnode;
	}
	nnode = &path->nnode;
	path->in_tree = 0;
	path->ptr.nnode = nnode;
	memset(nnode, 0, sizeof(struct ubifs_nnode));
	if (branch->lnum == 0) {
		/*
		 * This nnode was not written which just means that the LEB
		 * properties in the subtree below it describe empty LEBs. We
		 * make the nnode as though we had read it, which in fact means
		 * doing almost nothing.
		 */
		if (c->big_lpt)
			nnode->num = calc_nnode_num_from_parent(c, parent, iip);
	} else {
		err = ubi_read(c->ubi, branch->lnum, buf, branch->offs,
			       c->nnode_sz);
		if (err)
			return ERR_PTR(err);
		err = unpack_nnode(c, buf, nnode);
		if (err)
			return ERR_PTR(err);
	}
	err = validate_nnode(c, nnode, parent, iip);
	if (err)
		return ERR_PTR(err);
	if (!c->big_lpt)
		nnode->num = calc_nnode_num_from_parent(c, parent, iip);
	nnode->level = parent->level - 1;
	nnode->parent = parent;
	nnode->iip = iip;
	return nnode;
}

/**
 * scan_get_pnode - for the scan, get a pnode from either the tree or flash.
 * @c: the UBIFS file-system description object
 * @path: where to put the pnode
 * @parent: parent of the pnode
 * @iip: index in parent of the pnode
 *
 * This function returns a pointer to the pnode on success or a negative error
 * code on failure.
 */
static struct ubifs_pnode *scan_get_pnode(struct ubifs_info *c,
					  struct lpt_scan_node *path,
					  struct ubifs_nnode *parent, int iip)
{
	struct ubifs_nbranch *branch;
	struct ubifs_pnode *pnode;
	void *buf = c->lpt_nod_buf;
	int err;

	branch = &parent->nbranch[iip];
	pnode = branch->pnode;
	if (pnode) {
		path->in_tree = 1;
		path->ptr.pnode = pnode;
		return pnode;
	}
	pnode = &path->pnode;
	path->in_tree = 0;
	path->ptr.pnode = pnode;
	memset(pnode, 0, sizeof(struct ubifs_pnode));
	if (branch->lnum == 0) {
		/*
		 * This pnode was not written which just means that the LEB
		 * properties in it describe empty LEBs. We make the pnode as
		 * though we had read it.
		 */
		int i;

		if (c->big_lpt)
			pnode->num = calc_pnode_num_from_parent(c, parent, iip);
		for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
			struct ubifs_lprops * const lprops = &pnode->lprops[i];

			lprops->free = c->leb_size;
			lprops->flags = ubifs_categorize_lprops(c, lprops);
		}
	} else {
		ubifs_assert(branch->lnum >= c->lpt_first &&
			     branch->lnum <= c->lpt_last);
		ubifs_assert(branch->offs >= 0 && branch->offs < c->leb_size);
		err = ubi_read(c->ubi, branch->lnum, buf, branch->offs,
			       c->pnode_sz);
		if (err)
			return ERR_PTR(err);
		err = unpack_pnode(c, buf, pnode);
		if (err)
			return ERR_PTR(err);
	}
	err = validate_pnode(c, pnode, parent, iip);
	if (err)
		return ERR_PTR(err);
	if (!c->big_lpt)
		pnode->num = calc_pnode_num_from_parent(c, parent, iip);
	pnode->parent = parent;
	pnode->iip = iip;
	set_pnode_lnum(c, pnode);
	return pnode;
}

/**
 * ubifs_lpt_scan_nolock - scan the LPT.
 * @c: the UBIFS file-system description object
 * @start_lnum: LEB number from which to start scanning
 * @end_lnum: LEB number at which to stop scanning
 * @scan_cb: callback function called for each lprops
 * @data: data to be passed to the callback function
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int ubifs_lpt_scan_nolock(struct ubifs_info *c, int start_lnum, int end_lnum,
			  ubifs_lpt_scan_callback scan_cb, void *data)
{
	int err = 0, i, h, iip, shft;
	struct ubifs_nnode *nnode;
	struct ubifs_pnode *pnode;
	struct lpt_scan_node *path;

	if (start_lnum == -1) {
		start_lnum = end_lnum + 1;
		if (start_lnum >= c->leb_cnt)
			start_lnum = c->main_first;
	}

	ubifs_assert(start_lnum >= c->main_first && start_lnum < c->leb_cnt);
	ubifs_assert(end_lnum >= c->main_first && end_lnum < c->leb_cnt);

	if (!c->nroot) {
		err = ubifs_read_nnode(c, NULL, 0);
		if (err)
			return err;
	}

	path = kmalloc(sizeof(struct lpt_scan_node) * (c->lpt_hght + 1),
		       GFP_NOFS);
	if (!path)
		return -ENOMEM;

	path[0].ptr.nnode = c->nroot;
	path[0].in_tree = 1;
again:
	/* Descend to the pnode containing start_lnum */
	nnode = c->nroot;
	i = start_lnum - c->main_first;
	shft = c->lpt_hght * UBIFS_LPT_FANOUT_SHIFT;
	for (h = 1; h < c->lpt_hght; h++) {
		iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
		shft -= UBIFS_LPT_FANOUT_SHIFT;
		nnode = scan_get_nnode(c, path + h, nnode, iip);
		if (IS_ERR(nnode)) {
			err = PTR_ERR(nnode);
			goto out;
		}
	}
	iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
	shft -= UBIFS_LPT_FANOUT_SHIFT;
	pnode = scan_get_pnode(c, path + h, nnode, iip);
	if (IS_ERR(pnode)) {
		err = PTR_ERR(pnode);
		goto out;
	}
	iip = (i & (UBIFS_LPT_FANOUT - 1));

	/* Loop for each lprops */
	while (1) {
		struct ubifs_lprops *lprops = &pnode->lprops[iip];
		int ret, lnum = lprops->lnum;

		ret = scan_cb(c, lprops, path[h].in_tree, data);
		if (ret < 0) {
			err = ret;
			goto out;
		}
		if (ret & LPT_SCAN_ADD) {
			/* Add all the nodes in path to the tree in memory */
			for (h = 1; h < c->lpt_hght; h++) {
				const size_t sz = sizeof(struct ubifs_nnode);
				struct ubifs_nnode *parent;

				if (path[h].in_tree)
					continue;
				nnode = kmalloc(sz, GFP_NOFS);
				if (!nnode) {
					err = -ENOMEM;
					goto out;
				}
				memcpy(nnode, &path[h].nnode, sz);
				parent = nnode->parent;
				parent->nbranch[nnode->iip].nnode = nnode;
				path[h].ptr.nnode = nnode;
				path[h].in_tree = 1;
				path[h + 1].cnode.parent = nnode;
			}
			if (path[h].in_tree)
				ubifs_ensure_cat(c, lprops);
			else {
				const size_t sz = sizeof(struct ubifs_pnode);
				struct ubifs_nnode *parent;

				pnode = kmalloc(sz, GFP_NOFS);
				if (!pnode) {
					err = -ENOMEM;
					goto out;
				}
				memcpy(pnode, &path[h].pnode, sz);
				parent = pnode->parent;
				parent->nbranch[pnode->iip].pnode = pnode;
				path[h].ptr.pnode = pnode;
				path[h].in_tree = 1;
				update_cats(c, pnode);
				c->pnodes_have += 1;
			}
			err = dbg_check_lpt_nodes(c, (struct ubifs_cnode *)
						  c->nroot, 0, 0);
			if (err)
				goto out;
			err = dbg_check_cats(c);
			if (err)
				goto out;
		}
		if (ret & LPT_SCAN_STOP) {
			err = 0;
			break;
		}
		/* Get the next lprops */
		if (lnum == end_lnum) {
			/*
			 * We got to the end without finding what we were
			 * looking for
			 */
			err = -ENOSPC;
			goto out;
		}
		if (lnum + 1 >= c->leb_cnt) {
			/* Wrap-around to the beginning */
			start_lnum = c->main_first;
			goto again;
		}
		if (iip + 1 < UBIFS_LPT_FANOUT) {
			/* Next lprops is in the same pnode */
			iip += 1;
			continue;
		}
		/* We need to get the next pnode. Go up until we can go right */
		iip = pnode->iip;
		while (1) {
			h -= 1;
			ubifs_assert(h >= 0);
			nnode = path[h].ptr.nnode;
			if (iip + 1 < UBIFS_LPT_FANOUT)
				break;
			iip = nnode->iip;
		}
		/* Go right */
		iip += 1;
		/* Descend to the pnode */
		h += 1;
		for (; h < c->lpt_hght; h++) {
			nnode = scan_get_nnode(c, path + h, nnode, iip);
			if (IS_ERR(nnode)) {
				err = PTR_ERR(nnode);
				goto out;
			}
			iip = 0;
		}
		pnode = scan_get_pnode(c, path + h, nnode, iip);
		if (IS_ERR(pnode)) {
			err = PTR_ERR(pnode);
			goto out;
		}
		iip = 0;
	}
out:
	kfree(path);
	return err;
}

#ifdef CONFIG_UBIFS_FS_DEBUG

/**
 * dbg_chk_pnode - check a pnode.
 * @c: the UBIFS file-system description object
 * @pnode: pnode to check
 * @col: pnode column
 *
 * This function returns %0 on success and a negative error code on failure.
 */
static int dbg_chk_pnode(struct ubifs_info *c, struct ubifs_pnode *pnode,
			 int col)
{
	int i;

	if (pnode->num != col) {
		dbg_err("pnode num %d expected %d parent num %d iip %d",
			pnode->num, col, pnode->parent->num, pnode->iip);
		return -EINVAL;
	}
	for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
		struct ubifs_lprops *lp, *lprops = &pnode->lprops[i];
		int lnum = (pnode->num << UBIFS_LPT_FANOUT_SHIFT) + i +
			   c->main_first;
		int found, cat = lprops->flags & LPROPS_CAT_MASK;
		struct ubifs_lpt_heap *heap;
		struct list_head *list = NULL;

		if (lnum >= c->leb_cnt)
			continue;
		if (lprops->lnum != lnum) {
			dbg_err("bad LEB number %d expected %d",
				lprops->lnum, lnum);
			return -EINVAL;
		}
		if (lprops->flags & LPROPS_TAKEN) {
			if (cat != LPROPS_UNCAT) {
				dbg_err("LEB %d taken but not uncat %d",
					lprops->lnum, cat);
				return -EINVAL;
			}
			continue;
		}
		if (lprops->flags & LPROPS_INDEX) {
			switch (cat) {
			case LPROPS_UNCAT:
			case LPROPS_DIRTY_IDX:
			case LPROPS_FRDI_IDX:
				break;
			default:
				dbg_err("LEB %d index but cat %d",
					lprops->lnum, cat);
				return -EINVAL;
			}
		} else {
			switch (cat) {
			case LPROPS_UNCAT:
			case LPROPS_DIRTY:
			case LPROPS_FREE:
			case LPROPS_EMPTY:
			case LPROPS_FREEABLE:
				break;
			default:
				dbg_err("LEB %d not index but cat %d",
					lprops->lnum, cat);
				return -EINVAL;
			}
		}
		switch (cat) {
		case LPROPS_UNCAT:
			list = &c->uncat_list;
			break;
		case LPROPS_EMPTY:
			list = &c->empty_list;
			break;
		case LPROPS_FREEABLE:
			list = &c->freeable_list;
			break;
		case LPROPS_FRDI_IDX:
			list = &c->frdi_idx_list;
			break;
		}
		found = 0;
		switch (cat) {
		case LPROPS_DIRTY:
		case LPROPS_DIRTY_IDX:
		case LPROPS_FREE:
			heap = &c->lpt_heap[cat - 1];
			if (lprops->hpos < heap->cnt &&
			    heap->arr[lprops->hpos] == lprops)
				found = 1;
			break;
		case LPROPS_UNCAT:
		case LPROPS_EMPTY:
		case LPROPS_FREEABLE:
		case LPROPS_FRDI_IDX:
			list_for_each_entry(lp, list, list)
				if (lprops == lp) {
					found = 1;
					break;
				}
			break;
		}
		if (!found) {
			dbg_err("LEB %d cat %d not found in cat heap/list",
				lprops->lnum, cat);
			return -EINVAL;
		}
		switch (cat) {
		case LPROPS_EMPTY:
			if (lprops->free != c->leb_size) {
				dbg_err("LEB %d cat %d free %d dirty %d",
					lprops->lnum, cat, lprops->free,
					lprops->dirty);
				return -EINVAL;
			}
		case LPROPS_FREEABLE:
		case LPROPS_FRDI_IDX:
			if (lprops->free + lprops->dirty != c->leb_size) {
				dbg_err("LEB %d cat %d free %d dirty %d",
					lprops->lnum, cat, lprops->free,
					lprops->dirty);
				return -EINVAL;
			}
		}
	}
	return 0;
}

/**
 * dbg_check_lpt_nodes - check nnodes and pnodes.
 * @c: the UBIFS file-system description object
 * @cnode: next cnode (nnode or pnode) to check
 * @row: row of cnode (root is zero)
 * @col: column of cnode (leftmost is zero)
 *
 * This function returns %0 on success and a negative error code on failure.
 */
int dbg_check_lpt_nodes(struct ubifs_info *c, struct ubifs_cnode *cnode,
			int row, int col)
{
	struct ubifs_nnode *nnode, *nn;
	struct ubifs_cnode *cn;
	int num, iip = 0, err;

	if (!(ubifs_chk_flags & UBIFS_CHK_LPROPS))
		return 0;

	while (cnode) {
		ubifs_assert(row >= 0);
		nnode = cnode->parent;
		if (cnode->level) {
			/* cnode is a nnode */
			num = calc_nnode_num(row, col);
			if (cnode->num != num) {
				dbg_err("nnode num %d expected %d "
					"parent num %d iip %d", cnode->num, num,
					(nnode ? nnode->num : 0), cnode->iip);
				return -EINVAL;
			}
			nn = (struct ubifs_nnode *)cnode;
			while (iip < UBIFS_LPT_FANOUT) {
				cn = nn->nbranch[iip].cnode;
				if (cn) {
					/* Go down */
					row += 1;
					col <<= UBIFS_LPT_FANOUT_SHIFT;
					col += iip;
					iip = 0;
					cnode = cn;
					break;
				}
				/* Go right */
				iip += 1;
			}
			if (iip < UBIFS_LPT_FANOUT)
				continue;
		} else {
			struct ubifs_pnode *pnode;

			/* cnode is a pnode */
			pnode = (struct ubifs_pnode *)cnode;
			err = dbg_chk_pnode(c, pnode, col);
			if (err)
				return err;
		}
		/* Go up and to the right */
		row -= 1;
		col >>= UBIFS_LPT_FANOUT_SHIFT;
		iip = cnode->iip + 1;
		cnode = (struct ubifs_cnode *)nnode;
	}
	return 0;
}

#endif /* CONFIG_UBIFS_FS_DEBUG */