aboutsummaryrefslogblamecommitdiffstats
path: root/fs/ubifs/lpt.c
blob: 0084a33c4c69bba01e8a264bf7a6576ddede3744 (plain) (tree)
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
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
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273





































                                                                                
                                                                                





                                                                                
                  

                         
                       































































                                                                        

                                         























                                                                            
                     




                                                                     
                                                                 











                                                                                


















                                                                                
                     

























                                                                               
                                                                         

















































































                                                                            

                                                





                                   















                                                             


                                


















                                                             


                       
                         



























































































































































































































                                                                                
                                                                 























                                                                                
                                                                 





























































































































































































































































































































































































                                                                                
                                                              




























                                                                              
                                       





                                                                            

                                                             






























                                                                            
                                                             






























                                                                            
                                                              


























                                                                            
                                                                                










































                                                                            
                                                                                
































                                                                              

                                                      



















































                                                                                
                                                        






































































































































































































































                                                                                
                                               




                                                     
                                       

























































































































                                                                           
                                       






                                                             
                                               

                                                  
                                               




                                                     
                                       

                                          
                                       














































































































































































































                                                                                
                                                        







































































































































































































































































































































































































































































                                                                                
/*
 * 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 of marking the clean 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 "ubifs.h"
#include <linux/crc16.h>
#include <linux/math64.h>
#include <linux/slab.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;
	long long 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 */
	lebs_needed = div_u64(sz + c->leb_size - 1, c->leb_size);
	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;
	long long 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 */
		lebs_needed = div_u64(sz + c->leb_size - 1, c->leb_size);
		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 uninitialized_var(val);
	const int bytes = (nrbits + b + 7) >> 3;

	ubifs_assert(nrbits > 0);
	ubifs_assert(nrbits <= 32);
	ubifs_assert(*pos >= 0);
	ubifs_assert(*pos < 8);
	if (b) {
		switch (bytes) {
		case 2:
			val = p[1];
			break;
		case 3:
			val = p[1] | ((uint32_t)p[2] << 8);
			break;
		case 4:
			val = p[1] | ((uint32_t)p[2] << 8) |
				     ((uint32_t)p[3] << 16);
			break;
		case 5:
			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 {
		switch (bytes) {
		case 1:
			val = p[0];
			break;
		case 2:
			val = p[0] | ((uint32_t)p[1] << 8);
			break;
		case 3:
			val = p[0] | ((uint32_t)p[1] << 8) |
				     ((uint32_t)p[2] << 16);
			break;
		case 4:
			val = p[0] | ((uint32_t)p[1] << 8) |
				     ((uint32_t)p[2] << 16) |
				     ((uint32_t)p[3] << 24);
			break;
		}
	}
	val <<= k;
	val >>= k;
	b = nrbits & 7;
	p += nrbits >> 3;
	*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(const 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(const 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(const 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;
}

/**
 * ubifs_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.
 */
int ubifs_unpack_nnode(const 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(const 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(const 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(const 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(const 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(const 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 = ubifs_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_CAST(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_CAST(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_CAST(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_CAST(nnode);
		nnode = dirty_cow_nnode(c, nnode);
		if (IS_ERR(nnode))
			return ERR_CAST(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_CAST(pnode);
	pnode = dirty_cow_pnode(c, pnode);
	if (IS_ERR(pnode))
		return ERR_CAST(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 = ubifs_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 */