/*
 * 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(c, "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(c, "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(c, "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.
 * @c: UBIFS file-system description object
 * @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(const struct ubifs_info *c, uint8_t **addr, int *pos, uint32_t val, int nrbits)
{
        uint8_t *p = *addr;
        int b = *pos;

        ubifs_assert(c, nrbits > 0);
        ubifs_assert(c, nrbits <= 32);
        ubifs_assert(c, *pos >= 0);
        ubifs_assert(c, *pos < 8);
        ubifs_assert(c, (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.
 * @c: UBIFS file-system description object
 * @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(const struct ubifs_info *c, 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(c, nrbits > 0);
        ubifs_assert(c, nrbits <= 32);
        ubifs_assert(c, *pos >= 0);
        ubifs_assert(c, *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(c, (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(c, &addr, &pos, UBIFS_LPT_PNODE, UBIFS_LPT_TYPE_BITS);
        if (c->big_lpt)
                pack_bits(c, &addr, &pos, pnode->num, c->pcnt_bits);
        for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
                pack_bits(c, &addr, &pos, pnode->lprops[i].free >> 3,
                          c->space_bits);
                pack_bits(c, &addr, &pos, pnode->lprops[i].dirty >> 3,
                          c->space_bits);
                if (pnode->lprops[i].flags & LPROPS_INDEX)
                        pack_bits(c, &addr, &pos, 1, 1);
                else
                        pack_bits(c, &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(c, &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(c, &addr, &pos, UBIFS_LPT_NNODE, UBIFS_LPT_TYPE_BITS);
        if (c->big_lpt)
                pack_bits(c, &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(c, &addr, &pos, lnum - c->lpt_first, c->lpt_lnum_bits);
                pack_bits(c, &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(c, &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(c, &addr, &pos, UBIFS_LPT_LTAB, UBIFS_LPT_TYPE_BITS);
        for (i = 0; i < c->lpt_lebs; i++) {
                pack_bits(c, &addr, &pos, ltab[i].free, c->lpt_spc_bits);
                pack_bits(c, &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(c, &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(c, &addr, &pos, UBIFS_LPT_LSAVE, UBIFS_LPT_TYPE_BITS);
        for (i = 0; i < c->lsave_cnt; i++)
                pack_bits(c, &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(c, &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(c, 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(c, 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
 * @hash: hash of the LPT is 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, u8 *hash)
{
        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;
        struct shash_desc *desc;

        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;

        desc = ubifs_hash_get_desc(c);
        if (IS_ERR(desc))
                return PTR_ERR(desc);

        lsave = kmalloc_array(c->lsave_cnt, sizeof(int), 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(array_size(sizeof(struct ubifs_lpt_lprops),
                                  c->lpt_lebs));
        if (!pnode || !nnode || !buf || !ltab || !lsave) {
                err = -ENOMEM;
                goto out;
        }

        ubifs_assert(c, !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);
        err = ubifs_shash_update(c, desc, p, c->pnode_sz);
        if (err)
                goto out;

        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 = ubifs_leb_change(c, lnum++, buf, alen);
                        if (err)
                                goto out;
                        p = buf;
                        len = 0;
                }
                ubifs_pack_pnode(c, p, pnode);
                err = ubifs_shash_update(c, desc, p, c->pnode_sz);
                if (err)
                        goto out;

                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 = ubifs_leb_change(c, lnum++, buf, alen);
                                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 = ubifs_leb_change(c, lnum++, buf, alen);
                        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 = ubifs_leb_change(c, lnum++, buf, alen);
                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 = ubifs_leb_change(c, lnum, buf, alen);
        if (err)
                goto out;

        err = ubifs_shash_final(c, desc, hash);
        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(desc);
        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(const struct ubifs_info *c, void *buf, int len)
{
        int pos = 0;
        uint8_t *addr = buf;
        uint16_t crc, calc_crc;

        crc = ubifs_unpack_bits(c, &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(c, "invalid crc in LPT node: crc %hx calc %hx",
                          crc, calc_crc);
                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(const struct ubifs_info *c, uint8_t **addr,
                          int *pos, int type)
{
        int node_type;

        node_type = ubifs_unpack_bits(c, addr, pos, UBIFS_LPT_TYPE_BITS);
        if (node_type != type) {
                ubifs_err(c, "invalid type (%d) in LPT node type %d",
                          node_type, type);
                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(c, &addr, &pos, UBIFS_LPT_PNODE);
        if (err)
                return err;
        if (c->big_lpt)
                pnode->num = ubifs_unpack_bits(c, &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(c, &addr, &pos, c->space_bits);

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

                if (ubifs_unpack_bits(c, &addr, &pos, 1))
                        lprops->flags = LPROPS_INDEX;
                else
                        lprops->flags = 0;
                lprops->flags |= ubifs_categorize_lprops(c, lprops);
        }
        err = check_lpt_crc(c, 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(c, &addr, &pos, UBIFS_LPT_NNODE);
        if (err)
                return err;
        if (c->big_lpt)
                nnode->num = ubifs_unpack_bits(c, &addr, &pos, c->pcnt_bits);
        for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
                int lnum;

                lnum = ubifs_unpack_bits(c, &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(c, &addr, &pos,
                                                     c->lpt_offs_bits);
        }
        err = check_lpt_crc(c, 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(c, &addr, &pos, UBIFS_LPT_LTAB);
        if (err)
                return err;
        for (i = 0; i < c->lpt_lebs; i++) {
                int free = ubifs_unpack_bits(c, &addr, &pos, c->lpt_spc_bits);
                int dirty = ubifs_unpack_bits(c, &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(c, 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(c, &addr, &pos, UBIFS_LPT_LSAVE);
        if (err)
                return err;
        for (i = 0; i < c->lsave_cnt; i++) {
                int lnum = ubifs_unpack_bits(c, &addr, &pos, c->lnum_bits);

                if (lnum < c->main_first || lnum >= c->leb_cnt)
                        return -EINVAL;
                c->lsave[i] = lnum;
        }
        err = check_lpt_crc(c, 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 = ubifs_leb_read(c, lnum, buf, offs, c->nnode_sz, 1);
                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(c, "error %d reading nnode at %d:%d", err, lnum, offs);
        dump_stack();
        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)
                return -ENOMEM;

        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 = ubifs_leb_read(c, lnum, buf, offs, c->pnode_sz, 1);
                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(c, "error %d reading pnode at %d:%d", err, lnum, offs);
        ubifs_dump_pnode(c, pnode, parent, iip);
        dump_stack();
        ubifs_err(c, "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 = ubifs_leb_read(c, c->ltab_lnum, buf, c->ltab_offs, c->ltab_sz, 1);
        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 = ubifs_leb_read(c, c->lsave_lnum, buf, c->lsave_offs,
                             c->lsave_sz, 1);
        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];
                struct ubifs_lprops *lprops;

                /*
                 * 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;
                lprops = ubifs_lpt_lookup(c, lnum);
                if (IS_ERR(lprops)) {
                        err = PTR_ERR(lprops);
                        goto out;
                }
        }
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_pnode_lookup - lookup a pnode in the LPT.
 * @c: UBIFS file-system description object
 * @i: pnode number (0 to (main_lebs - 1) / UBIFS_LPT_FANOUT)
 *
 * This function returns a pointer to the pnode on success or a negative
 * error code on failure.
 */
struct ubifs_pnode *ubifs_pnode_lookup(struct ubifs_info *c, int i)
{
        int err, h, iip, shft;
        struct ubifs_nnode *nnode;

        if (!c->nroot) {
                err = ubifs_read_nnode(c, NULL, 0);
                if (err)
                        return ERR_PTR(err);
        }
        i <<= UBIFS_LPT_FANOUT_SHIFT;
        nnode = c->nroot;
        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));
        return ubifs_get_pnode(c, nnode, iip);
}

/**
 * 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 i, iip;
        struct ubifs_pnode *pnode;

        i = lnum - c->main_first;
        pnode = ubifs_pnode_lookup(c, i >> UBIFS_LPT_FANOUT_SHIFT);
        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 = kmemdup(nnode, sizeof(struct ubifs_nnode), GFP_NOFS);
        if (unlikely(!n))
                return ERR_PTR(-ENOMEM);

        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(c, !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 = kmemdup(pnode, sizeof(struct ubifs_pnode), GFP_NOFS);
        if (unlikely(!p))
                return ERR_PTR(-ENOMEM);

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

        ubifs_assert(c, !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));
        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(c, test_bit(DIRTY_CNODE, &pnode->flags));
        return &pnode->lprops[iip];
}

/**
 * ubifs_lpt_calc_hash - Calculate hash of the LPT pnodes
 * @c: UBIFS file-system description object
 * @hash: the returned hash of the LPT pnodes
 *
 * This function iterates over the LPT pnodes and creates a hash over them.
 * Returns 0 for success or a negative error code otherwise.
 */
int ubifs_lpt_calc_hash(struct ubifs_info *c, u8 *hash)
{
        struct ubifs_nnode *nnode, *nn;
        struct ubifs_cnode *cnode;
        struct shash_desc *desc;
        int iip = 0, i;
        int bufsiz = max_t(int, c->nnode_sz, c->pnode_sz);
        void *buf;
        int err;

        if (!ubifs_authenticated(c))
                return 0;

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

        desc = ubifs_hash_get_desc(c);
        if (IS_ERR(desc))
                return PTR_ERR(desc);

        buf = kmalloc(bufsiz, GFP_NOFS);
        if (!buf) {
                err = -ENOMEM;
                goto out;
        }

        cnode = (struct ubifs_cnode *)c->nroot;

        while (cnode) {
                nnode = cnode->parent;
                nn = (struct ubifs_nnode *)cnode;
                if (cnode->level > 1) {
                        while (iip < UBIFS_LPT_FANOUT) {
                                if (nn->nbranch[iip].lnum == 0) {
                                        /* Go right */
                                        iip++;
                                        continue;
                                }

                                nnode = ubifs_get_nnode(c, nn, iip);
                                if (IS_ERR(nnode)) {
                                        err = PTR_ERR(nnode);
                                        goto out;
                                }

                                /* Go down */
                                iip = 0;
                                cnode = (struct ubifs_cnode *)nnode;
                                break;
                        }
                        if (iip < UBIFS_LPT_FANOUT)
                                continue;
                } else {
                        struct ubifs_pnode *pnode;

                        for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
                                if (nn->nbranch[i].lnum == 0)
                                        continue;
                                pnode = ubifs_get_pnode(c, nn, i);
                                if (IS_ERR(pnode)) {
                                        err = PTR_ERR(pnode);
                                        goto out;
                                }

                                ubifs_pack_pnode(c, buf, pnode);
                                err = ubifs_shash_update(c, desc, buf,
                                                         c->pnode_sz);
                                if (err)
                                        goto out;
                        }
                }
                /* Go up and to the right */
                iip = cnode->iip + 1;
                cnode = (struct ubifs_cnode *)nnode;
        }

        err = ubifs_shash_final(c, desc, hash);
out:
        kfree(desc);
        kfree(buf);

        return err;
}

/**
 * lpt_check_hash - check the hash of the LPT.
 * @c: UBIFS file-system description object
 *
 * This function calculates a hash over all pnodes in the LPT and compares it with
 * the hash stored in the master node. Returns %0 on success and a negative error
 * code on failure.
 */
static int lpt_check_hash(struct ubifs_info *c)
{
        int err;
        u8 hash[UBIFS_HASH_ARR_SZ];

        if (!ubifs_authenticated(c))
                return 0;

        err = ubifs_lpt_calc_hash(c, hash);
        if (err)
                return err;

        if (ubifs_check_hash(c, c->mst_node->hash_lpt, hash)) {
                err = -EPERM;
                ubifs_err(c, "Failed to authenticate LPT");
        } else {
                err = 0;
        }

        return err;
}

/**
 * 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(array_size(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_array(LPT_HEAP_SZ,
                                                   sizeof(void *),
                                                   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_array(LPT_HEAP_SZ, sizeof(void *),
                                         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;

        err = lpt_check_hash(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(array_size(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_array(c->lsave_cnt, sizeof(int), 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)
                        goto out_err;
        }

        if (wr) {
                err = lpt_init_wr(c);
                if (err)
                        goto out_err;
        }

        return 0;

out_err:
        if (wr)
                ubifs_lpt_free(c, 1);
        if (rd)
                ubifs_lpt_free(c, 0);
        return err;
}

/**
 * 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 = ubifs_leb_read(c, branch->lnum, buf, branch->offs,
                                     c->nnode_sz, 1);
                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(c, branch->lnum >= c->lpt_first &&
                             branch->lnum <= c->lpt_last);
                ubifs_assert(c, branch->offs >= 0 && branch->offs < c->leb_size);
                err = ubifs_leb_read(c, branch->lnum, buf, branch->offs,
                                     c->pnode_sz, 1);
                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(c, start_lnum >= c->main_first && start_lnum < c->leb_cnt);
        ubifs_assert(c, 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_array(c->lpt_hght + 1, sizeof(struct lpt_scan_node),
                             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));
        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 = kmemdup(&path[h].nnode, sz, GFP_NOFS);
                                if (!nnode) {
                                        err = -ENOMEM;
                                        goto out;
                                }
                                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 = kmemdup(&path[h].pnode, sz, GFP_NOFS);
                                if (!pnode) {
                                        err = -ENOMEM;
                                        goto out;
                                }
                                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(c, 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;
}

/**
 * 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) {
                ubifs_err(c, "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) {
                        ubifs_err(c, "bad LEB number %d expected %d",
                                  lprops->lnum, lnum);
                        return -EINVAL;
                }
                if (lprops->flags & LPROPS_TAKEN) {
                        if (cat != LPROPS_UNCAT) {
                                ubifs_err(c, "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:
                                ubifs_err(c, "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:
                                ubifs_err(c, "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) {
                        ubifs_err(c, "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) {
                                ubifs_err(c, "LEB %d cat %d free %d dirty %d",
                                          lprops->lnum, cat, lprops->free,
                                          lprops->dirty);
                                return -EINVAL;
                        }
                        break;
                case LPROPS_FREEABLE:
                case LPROPS_FRDI_IDX:
                        if (lprops->free + lprops->dirty != c->leb_size) {
                                ubifs_err(c, "LEB %d cat %d free %d dirty %d",
                                          lprops->lnum, cat, lprops->free,
                                          lprops->dirty);
                                return -EINVAL;
                        }
                        break;
                }
        }
        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 (!dbg_is_chk_lprops(c))
                return 0;

        while (cnode) {
                ubifs_assert(c, row >= 0);
                nnode = cnode->parent;
                if (cnode->level) {
                        /* cnode is a nnode */
                        num = calc_nnode_num(row, col);
                        if (cnode->num != num) {
                                ubifs_err(c, "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;
}