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