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 functions that access LEB properties and their
   * categories. LEBs are categorized based on the needs of UBIFS, and the
   * categories are stored as either heaps or lists to provide a fast way of
   * finding a LEB in a particular category. For example, UBIFS may need to find
   * an empty LEB for the journal, or a very dirty LEB for garbage collection.
   */
  
  #include "ubifs.h"
  
  /**
   * get_heap_comp_val - get the LEB properties value for heap comparisons.
   * @lprops: LEB properties
   * @cat: LEB category
   */
  static int get_heap_comp_val(struct ubifs_lprops *lprops, int cat)
  {
  	switch (cat) {
  	case LPROPS_FREE:
  		return lprops->free;
  	case LPROPS_DIRTY_IDX:
  		return lprops->free + lprops->dirty;
  	default:
  		return lprops->dirty;
  	}
  }
  
  /**
   * move_up_lpt_heap - move a new heap entry up as far as possible.
   * @c: UBIFS file-system description object
   * @heap: LEB category heap
   * @lprops: LEB properties to move
   * @cat: LEB category
   *
   * New entries to a heap are added at the bottom and then moved up until the
   * parent's value is greater.  In the case of LPT's category heaps, the value
   * is either the amount of free space or the amount of dirty space, depending
   * on the category.
   */
  static void move_up_lpt_heap(struct ubifs_info *c, struct ubifs_lpt_heap *heap,
  			     struct ubifs_lprops *lprops, int cat)
  {
  	int val1, val2, hpos;
  
  	hpos = lprops->hpos;
  	if (!hpos)
  		return; /* Already top of the heap */
  	val1 = get_heap_comp_val(lprops, cat);
  	/* Compare to parent and, if greater, move up the heap */
  	do {
  		int ppos = (hpos - 1) / 2;
  
  		val2 = get_heap_comp_val(heap->arr[ppos], cat);
  		if (val2 >= val1)
  			return;
  		/* Greater than parent so move up */
  		heap->arr[ppos]->hpos = hpos;
  		heap->arr[hpos] = heap->arr[ppos];
  		heap->arr[ppos] = lprops;
  		lprops->hpos = ppos;
  		hpos = ppos;
  	} while (hpos);
  }
  
  /**
   * adjust_lpt_heap - move a changed heap entry up or down the heap.
   * @c: UBIFS file-system description object
   * @heap: LEB category heap
   * @lprops: LEB properties to move
   * @hpos: heap position of @lprops
   * @cat: LEB category
   *
   * Changed entries in a heap are moved up or down until the parent's value is
   * greater.  In the case of LPT's category heaps, the value is either the amount
   * of free space or the amount of dirty space, depending on the category.
   */
  static void adjust_lpt_heap(struct ubifs_info *c, struct ubifs_lpt_heap *heap,
  			    struct ubifs_lprops *lprops, int hpos, int cat)
  {
  	int val1, val2, val3, cpos;
  
  	val1 = get_heap_comp_val(lprops, cat);
  	/* Compare to parent and, if greater than parent, move up the heap */
  	if (hpos) {
  		int ppos = (hpos - 1) / 2;
  
  		val2 = get_heap_comp_val(heap->arr[ppos], cat);
  		if (val1 > val2) {
  			/* Greater than parent so move up */
  			while (1) {
  				heap->arr[ppos]->hpos = hpos;
  				heap->arr[hpos] = heap->arr[ppos];
  				heap->arr[ppos] = lprops;
  				lprops->hpos = ppos;
  				hpos = ppos;
  				if (!hpos)
  					return;
  				ppos = (hpos - 1) / 2;
  				val2 = get_heap_comp_val(heap->arr[ppos], cat);
  				if (val1 <= val2)
  					return;
  				/* Still greater than parent so keep going */
  			}
  		}
  	}
  
  	/* Not greater than parent, so compare to children */
  	while (1) {
  		/* Compare to left child */
  		cpos = hpos * 2 + 1;
  		if (cpos >= heap->cnt)
  			return;
  		val2 = get_heap_comp_val(heap->arr[cpos], cat);
  		if (val1 < val2) {
  			/* Less than left child, so promote biggest child */
  			if (cpos + 1 < heap->cnt) {
  				val3 = get_heap_comp_val(heap->arr[cpos + 1],
  							 cat);
  				if (val3 > val2)
  					cpos += 1; /* Right child is bigger */
  			}
  			heap->arr[cpos]->hpos = hpos;
  			heap->arr[hpos] = heap->arr[cpos];
  			heap->arr[cpos] = lprops;
  			lprops->hpos = cpos;
  			hpos = cpos;
  			continue;
  		}
  		/* Compare to right child */
  		cpos += 1;
  		if (cpos >= heap->cnt)
  			return;
  		val3 = get_heap_comp_val(heap->arr[cpos], cat);
  		if (val1 < val3) {
  			/* Less than right child, so promote right child */
  			heap->arr[cpos]->hpos = hpos;
  			heap->arr[hpos] = heap->arr[cpos];
  			heap->arr[cpos] = lprops;
  			lprops->hpos = cpos;
  			hpos = cpos;
  			continue;
  		}
  		return;
  	}
  }
  
  /**
   * add_to_lpt_heap - add LEB properties to a LEB category heap.
   * @c: UBIFS file-system description object
   * @lprops: LEB properties to add
   * @cat: LEB category
   *
   * This function returns %1 if @lprops is added to the heap for LEB category
   * @cat, otherwise %0 is returned because the heap is full.
   */
  static int add_to_lpt_heap(struct ubifs_info *c, struct ubifs_lprops *lprops,
  			   int cat)
  {
  	struct ubifs_lpt_heap *heap = &c->lpt_heap[cat - 1];
  
  	if (heap->cnt >= heap->max_cnt) {
  		const int b = LPT_HEAP_SZ / 2 - 1;
  		int cpos, val1, val2;
  
  		/* Compare to some other LEB on the bottom of heap */
  		/* Pick a position kind of randomly */
  		cpos = (((size_t)lprops >> 4) & b) + b;
  		ubifs_assert(cpos >= b);
  		ubifs_assert(cpos < LPT_HEAP_SZ);
  		ubifs_assert(cpos < heap->cnt);
  
  		val1 = get_heap_comp_val(lprops, cat);
  		val2 = get_heap_comp_val(heap->arr[cpos], cat);
  		if (val1 > val2) {
  			struct ubifs_lprops *lp;
  
  			lp = heap->arr[cpos];
  			lp->flags &= ~LPROPS_CAT_MASK;
  			lp->flags |= LPROPS_UNCAT;
  			list_add(&lp->list, &c->uncat_list);
  			lprops->hpos = cpos;
  			heap->arr[cpos] = lprops;
  			move_up_lpt_heap(c, heap, lprops, cat);
  			dbg_check_heap(c, heap, cat, lprops->hpos);
  			return 1; /* Added to heap */
  		}
  		dbg_check_heap(c, heap, cat, -1);
  		return 0; /* Not added to heap */
  	} else {
  		lprops->hpos = heap->cnt++;
  		heap->arr[lprops->hpos] = lprops;
  		move_up_lpt_heap(c, heap, lprops, cat);
  		dbg_check_heap(c, heap, cat, lprops->hpos);
  		return 1; /* Added to heap */
  	}
  }
  
  /**
   * remove_from_lpt_heap - remove LEB properties from a LEB category heap.
   * @c: UBIFS file-system description object
   * @lprops: LEB properties to remove
   * @cat: LEB category
   */
  static void remove_from_lpt_heap(struct ubifs_info *c,
  				 struct ubifs_lprops *lprops, int cat)
  {
  	struct ubifs_lpt_heap *heap;
  	int hpos = lprops->hpos;
  
  	heap = &c->lpt_heap[cat - 1];
  	ubifs_assert(hpos >= 0 && hpos < heap->cnt);
  	ubifs_assert(heap->arr[hpos] == lprops);
  	heap->cnt -= 1;
  	if (hpos < heap->cnt) {
  		heap->arr[hpos] = heap->arr[heap->cnt];
  		heap->arr[hpos]->hpos = hpos;
  		adjust_lpt_heap(c, heap, heap->arr[hpos], hpos, cat);
  	}
  	dbg_check_heap(c, heap, cat, -1);
  }
  
  /**
   * lpt_heap_replace - replace lprops in a category heap.
   * @c: UBIFS file-system description object
   * @old_lprops: LEB properties to replace
   * @new_lprops: LEB properties with which to replace
   * @cat: LEB category
   *
   * During commit it is sometimes necessary to copy a pnode (see dirty_cow_pnode)
   * and the lprops that the pnode contains.  When that happens, references in
   * the category heaps to those lprops must be updated to point to the new
   * lprops.  This function does that.
   */
  static void lpt_heap_replace(struct ubifs_info *c,
  			     struct ubifs_lprops *old_lprops,
  			     struct ubifs_lprops *new_lprops, int cat)
  {
  	struct ubifs_lpt_heap *heap;
  	int hpos = new_lprops->hpos;
  
  	heap = &c->lpt_heap[cat - 1];
  	heap->arr[hpos] = new_lprops;
  }
  
  /**
   * ubifs_add_to_cat - add LEB properties to a category list or heap.
   * @c: UBIFS file-system description object
   * @lprops: LEB properties to add
   * @cat: LEB category to which to add
   *
   * LEB properties are categorized to enable fast find operations.
   */
  void ubifs_add_to_cat(struct ubifs_info *c, struct ubifs_lprops *lprops,
  		      int cat)
  {
  	switch (cat) {
  	case LPROPS_DIRTY:
  	case LPROPS_DIRTY_IDX:
  	case LPROPS_FREE:
  		if (add_to_lpt_heap(c, lprops, cat))
  			break;
  		/* No more room on heap so make it un-categorized */
  		cat = LPROPS_UNCAT;
  		/* Fall through */
  	case LPROPS_UNCAT:
  		list_add(&lprops->list, &c->uncat_list);
  		break;
  	case LPROPS_EMPTY:
  		list_add(&lprops->list, &c->empty_list);
  		break;
  	case LPROPS_FREEABLE:
  		list_add(&lprops->list, &c->freeable_list);
  		c->freeable_cnt += 1;
  		break;
  	case LPROPS_FRDI_IDX:
  		list_add(&lprops->list, &c->frdi_idx_list);
  		break;
  	default:
  		ubifs_assert(0);
  	}
  
  	lprops->flags &= ~LPROPS_CAT_MASK;
  	lprops->flags |= cat;
  	c->in_a_category_cnt += 1;
  	ubifs_assert(c->in_a_category_cnt <= c->main_lebs);
  }
  
  /**
   * ubifs_remove_from_cat - remove LEB properties from a category list or heap.
   * @c: UBIFS file-system description object
   * @lprops: LEB properties to remove
   * @cat: LEB category from which to remove
   *
   * LEB properties are categorized to enable fast find operations.
   */
  static void ubifs_remove_from_cat(struct ubifs_info *c,
  				  struct ubifs_lprops *lprops, int cat)
  {
  	switch (cat) {
  	case LPROPS_DIRTY:
  	case LPROPS_DIRTY_IDX:
  	case LPROPS_FREE:
  		remove_from_lpt_heap(c, lprops, cat);
  		break;
  	case LPROPS_FREEABLE:
  		c->freeable_cnt -= 1;
  		ubifs_assert(c->freeable_cnt >= 0);
  		/* Fall through */
  	case LPROPS_UNCAT:
  	case LPROPS_EMPTY:
  	case LPROPS_FRDI_IDX:
  		ubifs_assert(!list_empty(&lprops->list));
  		list_del(&lprops->list);
  		break;
  	default:
  		ubifs_assert(0);
  	}
  
  	c->in_a_category_cnt -= 1;
  	ubifs_assert(c->in_a_category_cnt >= 0);
  }
  
  /**
   * ubifs_replace_cat - replace lprops in a category list or heap.
   * @c: UBIFS file-system description object
   * @old_lprops: LEB properties to replace
   * @new_lprops: LEB properties with which to replace
   *
   * During commit it is sometimes necessary to copy a pnode (see dirty_cow_pnode)
   * and the lprops that the pnode contains. When that happens, references in
   * category lists and heaps must be replaced. This function does that.
   */
  void ubifs_replace_cat(struct ubifs_info *c, struct ubifs_lprops *old_lprops,
  		       struct ubifs_lprops *new_lprops)
  {
  	int cat;
  
  	cat = new_lprops->flags & LPROPS_CAT_MASK;
  	switch (cat) {
  	case LPROPS_DIRTY:
  	case LPROPS_DIRTY_IDX:
  	case LPROPS_FREE:
  		lpt_heap_replace(c, old_lprops, new_lprops, cat);
  		break;
  	case LPROPS_UNCAT:
  	case LPROPS_EMPTY:
  	case LPROPS_FREEABLE:
  	case LPROPS_FRDI_IDX:
  		list_replace(&old_lprops->list, &new_lprops->list);
  		break;
  	default:
  		ubifs_assert(0);
  	}
  }
  
  /**
   * ubifs_ensure_cat - ensure LEB properties are categorized.
   * @c: UBIFS file-system description object
   * @lprops: LEB properties
   *
   * A LEB may have fallen off of the bottom of a heap, and ended up as
   * un-categorized even though it has enough space for us now. If that is the
   * case this function will put the LEB back onto a heap.
   */
  void ubifs_ensure_cat(struct ubifs_info *c, struct ubifs_lprops *lprops)
  {
  	int cat = lprops->flags & LPROPS_CAT_MASK;
  
  	if (cat != LPROPS_UNCAT)
  		return;
  	cat = ubifs_categorize_lprops(c, lprops);
  	if (cat == LPROPS_UNCAT)
  		return;
  	ubifs_remove_from_cat(c, lprops, LPROPS_UNCAT);
  	ubifs_add_to_cat(c, lprops, cat);
  }
  
  /**
   * ubifs_categorize_lprops - categorize LEB properties.
   * @c: UBIFS file-system description object
   * @lprops: LEB properties to categorize
   *
   * LEB properties are categorized to enable fast find operations. This function
   * returns the LEB category to which the LEB properties belong. Note however
   * that if the LEB category is stored as a heap and the heap is full, the
   * LEB properties may have their category changed to %LPROPS_UNCAT.
   */
  int ubifs_categorize_lprops(const struct ubifs_info *c,
  			    const struct ubifs_lprops *lprops)
  {
  	if (lprops->flags & LPROPS_TAKEN)
  		return LPROPS_UNCAT;
  
  	if (lprops->free == c->leb_size) {
  		ubifs_assert(!(lprops->flags & LPROPS_INDEX));
  		return LPROPS_EMPTY;
  	}
  
  	if (lprops->free + lprops->dirty == c->leb_size) {
  		if (lprops->flags & LPROPS_INDEX)
  			return LPROPS_FRDI_IDX;
  		else
  			return LPROPS_FREEABLE;
  	}
  
  	if (lprops->flags & LPROPS_INDEX) {
  		if (lprops->dirty + lprops->free >= c->min_idx_node_sz)
  			return LPROPS_DIRTY_IDX;
  	} else {
  		if (lprops->dirty >= c->dead_wm &&
  		    lprops->dirty > lprops->free)
  			return LPROPS_DIRTY;
  		if (lprops->free > 0)
  			return LPROPS_FREE;
  	}
  
  	return LPROPS_UNCAT;
  }
  
  /**
   * change_category - change LEB properties category.
   * @c: UBIFS file-system description object
   * @lprops: LEB properties to re-categorize
   *
   * LEB properties are categorized to enable fast find operations. When the LEB
   * properties change they must be re-categorized.
   */
  static void change_category(struct ubifs_info *c, struct ubifs_lprops *lprops)
  {
  	int old_cat = lprops->flags & LPROPS_CAT_MASK;
  	int new_cat = ubifs_categorize_lprops(c, lprops);
  
  	if (old_cat == new_cat) {
  		struct ubifs_lpt_heap *heap;
  
  		/* lprops on a heap now must be moved up or down */
  		if (new_cat < 1 || new_cat > LPROPS_HEAP_CNT)
  			return; /* Not on a heap */
  		heap = &c->lpt_heap[new_cat - 1];
  		adjust_lpt_heap(c, heap, lprops, lprops->hpos, new_cat);
  	} else {
  		ubifs_remove_from_cat(c, lprops, old_cat);
  		ubifs_add_to_cat(c, lprops, new_cat);
  	}
  }
  
  /**
   * ubifs_calc_dark - calculate LEB dark space size.
   * @c: the UBIFS file-system description object
   * @spc: amount of free and dirty space in the LEB
   *
   * This function calculates and returns amount of dark space in an LEB which
   * has @spc bytes of free and dirty space.
   *
   * UBIFS is trying to account the space which might not be usable, and this
   * space is called "dark space". For example, if an LEB has only %512 free
   * bytes, it is dark space, because it cannot fit a large data node.
   */
  int ubifs_calc_dark(const struct ubifs_info *c, int spc)
  {
  	ubifs_assert(!(spc & 7));
  
  	if (spc < c->dark_wm)
  		return spc;
  
  	/*
  	 * If we have slightly more space then the dark space watermark, we can
  	 * anyway safely assume it we'll be able to write a node of the
  	 * smallest size there.
  	 */
  	if (spc - c->dark_wm < MIN_WRITE_SZ)
  		return spc - MIN_WRITE_SZ;
  
  	return c->dark_wm;
  }
  
  /**
   * is_lprops_dirty - determine if LEB properties are dirty.
   * @c: the UBIFS file-system description object
   * @lprops: LEB properties to test
   */
  static int is_lprops_dirty(struct ubifs_info *c, struct ubifs_lprops *lprops)
  {
  	struct ubifs_pnode *pnode;
  	int pos;
  
  	pos = (lprops->lnum - c->main_first) & (UBIFS_LPT_FANOUT - 1);
  	pnode = (struct ubifs_pnode *)container_of(lprops - pos,
  						   struct ubifs_pnode,
  						   lprops[0]);
  	return !test_bit(COW_CNODE, &pnode->flags) &&
  	       test_bit(DIRTY_CNODE, &pnode->flags);
  }
  
  /**
   * ubifs_change_lp - change LEB properties.
   * @c: the UBIFS file-system description object
   * @lp: LEB properties to change
   * @free: new free space amount
   * @dirty: new dirty space amount
   * @flags: new flags
   * @idx_gc_cnt: change to the count of @idx_gc list
   *
   * This function changes LEB properties (@free, @dirty or @flag). However, the
   * property which has the %LPROPS_NC value is not changed. Returns a pointer to
   * the updated LEB properties on success and a negative error code on failure.
   *
   * Note, the LEB properties may have had to be copied (due to COW) and
   * consequently the pointer returned may not be the same as the pointer
   * passed.
   */
  const struct ubifs_lprops *ubifs_change_lp(struct ubifs_info *c,
  					   const struct ubifs_lprops *lp,
  					   int free, int dirty, int flags,
  					   int idx_gc_cnt)
  {
  	/*
  	 * This is the only function that is allowed to change lprops, so we
  	 * discard the "const" qualifier.
  	 */
  	struct ubifs_lprops *lprops = (struct ubifs_lprops *)lp;
  
  	dbg_lp("LEB %d, free %d, dirty %d, flags %d",
  	       lprops->lnum, free, dirty, flags);
  
  	ubifs_assert(mutex_is_locked(&c->lp_mutex));
  	ubifs_assert(c->lst.empty_lebs >= 0 &&
  		     c->lst.empty_lebs <= c->main_lebs);
  	ubifs_assert(c->freeable_cnt >= 0);
  	ubifs_assert(c->freeable_cnt <= c->main_lebs);
  	ubifs_assert(c->lst.taken_empty_lebs >= 0);
  	ubifs_assert(c->lst.taken_empty_lebs <= c->lst.empty_lebs);
  	ubifs_assert(!(c->lst.total_free & 7) && !(c->lst.total_dirty & 7));
  	ubifs_assert(!(c->lst.total_dead & 7) && !(c->lst.total_dark & 7));
  	ubifs_assert(!(c->lst.total_used & 7));
  	ubifs_assert(free == LPROPS_NC || free >= 0);
  	ubifs_assert(dirty == LPROPS_NC || dirty >= 0);
  
  	if (!is_lprops_dirty(c, lprops)) {
  		lprops = ubifs_lpt_lookup_dirty(c, lprops->lnum);
  		if (IS_ERR(lprops))
  			return lprops;
  	} else
  		ubifs_assert(lprops == ubifs_lpt_lookup_dirty(c, lprops->lnum));
  
  	ubifs_assert(!(lprops->free & 7) && !(lprops->dirty & 7));
  
  	spin_lock(&c->space_lock);
  	if ((lprops->flags & LPROPS_TAKEN) && lprops->free == c->leb_size)
  		c->lst.taken_empty_lebs -= 1;
  
  	if (!(lprops->flags & LPROPS_INDEX)) {
  		int old_spc;
  
  		old_spc = lprops->free + lprops->dirty;
  		if (old_spc < c->dead_wm)
  			c->lst.total_dead -= old_spc;
  		else
  			c->lst.total_dark -= ubifs_calc_dark(c, old_spc);
  
  		c->lst.total_used -= c->leb_size - old_spc;
  	}
  
  	if (free != LPROPS_NC) {
  		free = ALIGN(free, 8);
  		c->lst.total_free += free - lprops->free;
  
  		/* Increase or decrease empty LEBs counter if needed */
  		if (free == c->leb_size) {
  			if (lprops->free != c->leb_size)
  				c->lst.empty_lebs += 1;
  		} else if (lprops->free == c->leb_size)
  			c->lst.empty_lebs -= 1;
  		lprops->free = free;
  	}
  
  	if (dirty != LPROPS_NC) {
  		dirty = ALIGN(dirty, 8);
  		c->lst.total_dirty += dirty - lprops->dirty;
  		lprops->dirty = dirty;
  	}
  
  	if (flags != LPROPS_NC) {
  		/* Take care about indexing LEBs counter if needed */
  		if ((lprops->flags & LPROPS_INDEX)) {
  			if (!(flags & LPROPS_INDEX))
  				c->lst.idx_lebs -= 1;
  		} else if (flags & LPROPS_INDEX)
  			c->lst.idx_lebs += 1;
  		lprops->flags = flags;
  	}
  
  	if (!(lprops->flags & LPROPS_INDEX)) {
  		int new_spc;
  
  		new_spc = lprops->free + lprops->dirty;
  		if (new_spc < c->dead_wm)
  			c->lst.total_dead += new_spc;
  		else
  			c->lst.total_dark += ubifs_calc_dark(c, new_spc);
  
  		c->lst.total_used += c->leb_size - new_spc;
  	}
  
  	if ((lprops->flags & LPROPS_TAKEN) && lprops->free == c->leb_size)
  		c->lst.taken_empty_lebs += 1;
  
  	change_category(c, lprops);
  	c->idx_gc_cnt += idx_gc_cnt;
  	spin_unlock(&c->space_lock);
  	return lprops;
  }
  
  /**
   * ubifs_get_lp_stats - get lprops statistics.
   * @c: UBIFS file-system description object
   * @st: return statistics
   */
  void ubifs_get_lp_stats(struct ubifs_info *c, struct ubifs_lp_stats *lst)
  {
  	spin_lock(&c->space_lock);
  	memcpy(lst, &c->lst, sizeof(struct ubifs_lp_stats));
  	spin_unlock(&c->space_lock);
  }
  
  /**
   * ubifs_change_one_lp - change LEB properties.
   * @c: the UBIFS file-system description object
   * @lnum: LEB to change properties for
   * @free: amount of free space
   * @dirty: amount of dirty space
   * @flags_set: flags to set
   * @flags_clean: flags to clean
   * @idx_gc_cnt: change to the count of idx_gc list
   *
   * This function changes properties of LEB @lnum. It is a helper wrapper over
   * 'ubifs_change_lp()' which hides lprops get/release. The arguments are the
   * same as in case of 'ubifs_change_lp()'. Returns zero in case of success and
   * a negative error code in case of failure.
   */
  int ubifs_change_one_lp(struct ubifs_info *c, int lnum, int free, int dirty,
  			int flags_set, int flags_clean, int idx_gc_cnt)
  {
  	int err = 0, flags;
  	const struct ubifs_lprops *lp;
  
  	ubifs_get_lprops(c);
  
  	lp = ubifs_lpt_lookup_dirty(c, lnum);
  	if (IS_ERR(lp)) {
  		err = PTR_ERR(lp);
  		goto out;
  	}
  
  	flags = (lp->flags | flags_set) & ~flags_clean;
  	lp = ubifs_change_lp(c, lp, free, dirty, flags, idx_gc_cnt);
  	if (IS_ERR(lp))
  		err = PTR_ERR(lp);
  
  out:
  	ubifs_release_lprops(c);
  	if (err)
  		ubifs_err(c, "cannot change properties of LEB %d, error %d",
  			  lnum, err);
  	return err;
  }
  
  /**
   * ubifs_update_one_lp - update LEB properties.
   * @c: the UBIFS file-system description object
   * @lnum: LEB to change properties for
   * @free: amount of free space
   * @dirty: amount of dirty space to add
   * @flags_set: flags to set
   * @flags_clean: flags to clean
   *
   * This function is the same as 'ubifs_change_one_lp()' but @dirty is added to
   * current dirty space, not substitutes it.
   */
  int ubifs_update_one_lp(struct ubifs_info *c, int lnum, int free, int dirty,
  			int flags_set, int flags_clean)
  {
  	int err = 0, flags;
  	const struct ubifs_lprops *lp;
  
  	ubifs_get_lprops(c);
  
  	lp = ubifs_lpt_lookup_dirty(c, lnum);
  	if (IS_ERR(lp)) {
  		err = PTR_ERR(lp);
  		goto out;
  	}
  
  	flags = (lp->flags | flags_set) & ~flags_clean;
  	lp = ubifs_change_lp(c, lp, free, lp->dirty + dirty, flags, 0);
  	if (IS_ERR(lp))
  		err = PTR_ERR(lp);
  
  out:
  	ubifs_release_lprops(c);
  	if (err)
  		ubifs_err(c, "cannot update properties of LEB %d, error %d",
  			  lnum, err);
  	return err;
  }
  
  /**
   * ubifs_read_one_lp - read LEB properties.
   * @c: the UBIFS file-system description object
   * @lnum: LEB to read properties for
   * @lp: where to store read properties
   *
   * This helper function reads properties of a LEB @lnum and stores them in @lp.
   * Returns zero in case of success and a negative error code in case of
   * failure.
   */
  int ubifs_read_one_lp(struct ubifs_info *c, int lnum, struct ubifs_lprops *lp)
  {
  	int err = 0;
  	const struct ubifs_lprops *lpp;
  
  	ubifs_get_lprops(c);
  
  	lpp = ubifs_lpt_lookup(c, lnum);
  	if (IS_ERR(lpp)) {
  		err = PTR_ERR(lpp);
  		ubifs_err(c, "cannot read properties of LEB %d, error %d",
  			  lnum, err);
  		goto out;
  	}
  
  	memcpy(lp, lpp, sizeof(struct ubifs_lprops));
  
  out:
  	ubifs_release_lprops(c);
  	return err;
  }
  
  /**
   * ubifs_fast_find_free - try to find a LEB with free space quickly.
   * @c: the UBIFS file-system description object
   *
   * This function returns LEB properties for a LEB with free space or %NULL if
   * the function is unable to find a LEB quickly.
   */
  const struct ubifs_lprops *ubifs_fast_find_free(struct ubifs_info *c)
  {
  	struct ubifs_lprops *lprops;
  	struct ubifs_lpt_heap *heap;
  
  	ubifs_assert(mutex_is_locked(&c->lp_mutex));
  
  	heap = &c->lpt_heap[LPROPS_FREE - 1];
  	if (heap->cnt == 0)
  		return NULL;
  
  	lprops = heap->arr[0];
  	ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
  	ubifs_assert(!(lprops->flags & LPROPS_INDEX));
  	return lprops;
  }
  
  /**
   * ubifs_fast_find_empty - try to find an empty LEB quickly.
   * @c: the UBIFS file-system description object
   *
   * This function returns LEB properties for an empty LEB or %NULL if the
   * function is unable to find an empty LEB quickly.
   */
  const struct ubifs_lprops *ubifs_fast_find_empty(struct ubifs_info *c)
  {
  	struct ubifs_lprops *lprops;
  
  	ubifs_assert(mutex_is_locked(&c->lp_mutex));
  
  	if (list_empty(&c->empty_list))
  		return NULL;
  
  	lprops = list_entry(c->empty_list.next, struct ubifs_lprops, list);
  	ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
  	ubifs_assert(!(lprops->flags & LPROPS_INDEX));
  	ubifs_assert(lprops->free == c->leb_size);
  	return lprops;
  }
  
  /**
   * ubifs_fast_find_freeable - try to find a freeable LEB quickly.
   * @c: the UBIFS file-system description object
   *
   * This function returns LEB properties for a freeable LEB or %NULL if the
   * function is unable to find a freeable LEB quickly.
   */
  const struct ubifs_lprops *ubifs_fast_find_freeable(struct ubifs_info *c)
  {
  	struct ubifs_lprops *lprops;
  
  	ubifs_assert(mutex_is_locked(&c->lp_mutex));
  
  	if (list_empty(&c->freeable_list))
  		return NULL;
  
  	lprops = list_entry(c->freeable_list.next, struct ubifs_lprops, list);
  	ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
  	ubifs_assert(!(lprops->flags & LPROPS_INDEX));
  	ubifs_assert(lprops->free + lprops->dirty == c->leb_size);
  	ubifs_assert(c->freeable_cnt > 0);
  	return lprops;
  }
  
  /**
   * ubifs_fast_find_frdi_idx - try to find a freeable index LEB quickly.
   * @c: the UBIFS file-system description object
   *
   * This function returns LEB properties for a freeable index LEB or %NULL if the
   * function is unable to find a freeable index LEB quickly.
   */
  const struct ubifs_lprops *ubifs_fast_find_frdi_idx(struct ubifs_info *c)
  {
  	struct ubifs_lprops *lprops;
  
  	ubifs_assert(mutex_is_locked(&c->lp_mutex));
  
  	if (list_empty(&c->frdi_idx_list))
  		return NULL;
  
  	lprops = list_entry(c->frdi_idx_list.next, struct ubifs_lprops, list);
  	ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
  	ubifs_assert((lprops->flags & LPROPS_INDEX));
  	ubifs_assert(lprops->free + lprops->dirty == c->leb_size);
  	return lprops;
  }
  
  /*
   * Everything below is related to debugging.
   */
  
  /**
   * dbg_check_cats - check category heaps and lists.
   * @c: UBIFS file-system description object
   *
   * This function returns %0 on success and a negative error code on failure.
   */
  int dbg_check_cats(struct ubifs_info *c)
  {
  	struct ubifs_lprops *lprops;
  	struct list_head *pos;
  	int i, cat;
  
  	if (!dbg_is_chk_gen(c) && !dbg_is_chk_lprops(c))
  		return 0;
  
  	list_for_each_entry(lprops, &c->empty_list, list) {
  		if (lprops->free != c->leb_size) {
  			ubifs_err(c, "non-empty LEB %d on empty list (free %d dirty %d flags %d)",
  				  lprops->lnum, lprops->free, lprops->dirty,
  				  lprops->flags);
  			return -EINVAL;
  		}
  		if (lprops->flags & LPROPS_TAKEN) {
  			ubifs_err(c, "taken LEB %d on empty list (free %d dirty %d flags %d)",
  				  lprops->lnum, lprops->free, lprops->dirty,
  				  lprops->flags);
  			return -EINVAL;
  		}
  	}
  
  	i = 0;
  	list_for_each_entry(lprops, &c->freeable_list, list) {
  		if (lprops->free + lprops->dirty != c->leb_size) {
  			ubifs_err(c, "non-freeable LEB %d on freeable list (free %d dirty %d flags %d)",
  				  lprops->lnum, lprops->free, lprops->dirty,
  				  lprops->flags);
  			return -EINVAL;
  		}
  		if (lprops->flags & LPROPS_TAKEN) {
  			ubifs_err(c, "taken LEB %d on freeable list (free %d dirty %d flags %d)",
  				  lprops->lnum, lprops->free, lprops->dirty,
  				  lprops->flags);
  			return -EINVAL;
  		}
  		i += 1;
  	}
  	if (i != c->freeable_cnt) {
  		ubifs_err(c, "freeable list count %d expected %d", i,
  			  c->freeable_cnt);
  		return -EINVAL;
  	}
  
  	i = 0;
  	list_for_each(pos, &c->idx_gc)
  		i += 1;
  	if (i != c->idx_gc_cnt) {
  		ubifs_err(c, "idx_gc list count %d expected %d", i,
  			  c->idx_gc_cnt);
  		return -EINVAL;
  	}
  
  	list_for_each_entry(lprops, &c->frdi_idx_list, list) {
  		if (lprops->free + lprops->dirty != c->leb_size) {
  			ubifs_err(c, "non-freeable LEB %d on frdi_idx list (free %d dirty %d flags %d)",
  				  lprops->lnum, lprops->free, lprops->dirty,
  				  lprops->flags);
  			return -EINVAL;
  		}
  		if (lprops->flags & LPROPS_TAKEN) {
  			ubifs_err(c, "taken LEB %d on frdi_idx list (free %d dirty %d flags %d)",
  				  lprops->lnum, lprops->free, lprops->dirty,
  				  lprops->flags);
  			return -EINVAL;
  		}
  		if (!(lprops->flags & LPROPS_INDEX)) {
  			ubifs_err(c, "non-index LEB %d on frdi_idx list (free %d dirty %d flags %d)",
  				  lprops->lnum, lprops->free, lprops->dirty,
  				  lprops->flags);
  			return -EINVAL;
  		}
  	}
  
  	for (cat = 1; cat <= LPROPS_HEAP_CNT; cat++) {
  		struct ubifs_lpt_heap *heap = &c->lpt_heap[cat - 1];
  
  		for (i = 0; i < heap->cnt; i++) {
  			lprops = heap->arr[i];
  			if (!lprops) {
  				ubifs_err(c, "null ptr in LPT heap cat %d", cat);
  				return -EINVAL;
  			}
  			if (lprops->hpos != i) {
  				ubifs_err(c, "bad ptr in LPT heap cat %d", cat);
  				return -EINVAL;
  			}
  			if (lprops->flags & LPROPS_TAKEN) {
  				ubifs_err(c, "taken LEB in LPT heap cat %d", cat);
  				return -EINVAL;
  			}
  		}
  	}
  
  	return 0;
  }
  
  void dbg_check_heap(struct ubifs_info *c, struct ubifs_lpt_heap *heap, int cat,
  		    int add_pos)
  {
  	int i = 0, j, err = 0;
  
  	if (!dbg_is_chk_gen(c) && !dbg_is_chk_lprops(c))
  		return;
  
  	for (i = 0; i < heap->cnt; i++) {
  		struct ubifs_lprops *lprops = heap->arr[i];
  		struct ubifs_lprops *lp;
  
  		if (i != add_pos)
  			if ((lprops->flags & LPROPS_CAT_MASK) != cat) {
  				err = 1;
  				goto out;
  			}
  		if (lprops->hpos != i) {
  			err = 2;
  			goto out;
  		}
  		lp = ubifs_lpt_lookup(c, lprops->lnum);
  		if (IS_ERR(lp)) {
  			err = 3;
  			goto out;
  		}
  		if (lprops != lp) {
  			ubifs_err(c, "lprops %zx lp %zx lprops->lnum %d lp->lnum %d",
  				  (size_t)lprops, (size_t)lp, lprops->lnum,
  				  lp->lnum);
  			err = 4;
  			goto out;
  		}
  		for (j = 0; j < i; j++) {
  			lp = heap->arr[j];
  			if (lp == lprops) {
  				err = 5;
  				goto out;
  			}
  			if (lp->lnum == lprops->lnum) {
  				err = 6;
  				goto out;
  			}
  		}
  	}
  out:
  	if (err) {
  		ubifs_err(c, "failed cat %d hpos %d err %d", cat, i, err);
  		dump_stack();
  		ubifs_dump_heap(c, heap, cat);
  	}
  }
  
  /**
   * scan_check_cb - scan callback.
   * @c: the UBIFS file-system description object
   * @lp: LEB properties to scan
   * @in_tree: whether the LEB properties are in main memory
   * @lst: lprops statistics to update
   *
   * This function returns a code that indicates whether the scan should continue
   * (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
   * in main memory (%LPT_SCAN_ADD), or whether the scan should stop
   * (%LPT_SCAN_STOP).
   */
  static int scan_check_cb(struct ubifs_info *c,
  			 const struct ubifs_lprops *lp, int in_tree,
  			 struct ubifs_lp_stats *lst)
  {
  	struct ubifs_scan_leb *sleb;
  	struct ubifs_scan_node *snod;
  	int cat, lnum = lp->lnum, is_idx = 0, used = 0, free, dirty, ret;
  	void *buf = NULL;
  
  	cat = lp->flags & LPROPS_CAT_MASK;
  	if (cat != LPROPS_UNCAT) {
  		cat = ubifs_categorize_lprops(c, lp);
  		if (cat != (lp->flags & LPROPS_CAT_MASK)) {
  			ubifs_err(c, "bad LEB category %d expected %d",
  				  (lp->flags & LPROPS_CAT_MASK), cat);
  			return -EINVAL;
  		}
  	}
  
  	/* Check lp is on its category list (if it has one) */
  	if (in_tree) {
  		struct list_head *list = NULL;
  
  		switch (cat) {
  		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;
  		case LPROPS_UNCAT:
  			list = &c->uncat_list;
  			break;
  		}
  		if (list) {
  			struct ubifs_lprops *lprops;
  			int found = 0;
  
  			list_for_each_entry(lprops, list, list) {
  				if (lprops == lp) {
  					found = 1;
  					break;
  				}
  			}
  			if (!found) {
  				ubifs_err(c, "bad LPT list (category %d)", cat);
  				return -EINVAL;
  			}
  		}
  	}
  
  	/* Check lp is on its category heap (if it has one) */
  	if (in_tree && cat > 0 && cat <= LPROPS_HEAP_CNT) {
  		struct ubifs_lpt_heap *heap = &c->lpt_heap[cat - 1];
  
  		if ((lp->hpos != -1 && heap->arr[lp->hpos]->lnum != lnum) ||
  		    lp != heap->arr[lp->hpos]) {
  			ubifs_err(c, "bad LPT heap (category %d)", cat);
  			return -EINVAL;
  		}
  	}
  
  	buf = __vmalloc(c->leb_size, GFP_NOFS, PAGE_KERNEL);
  	if (!buf)
  		return -ENOMEM;
  
  	/*
  	 * After an unclean unmount, empty and freeable LEBs
  	 * may contain garbage - do not scan them.
  	 */
  	if (lp->free == c->leb_size) {
  		lst->empty_lebs += 1;
  		lst->total_free += c->leb_size;
  		lst->total_dark += ubifs_calc_dark(c, c->leb_size);
  		return LPT_SCAN_CONTINUE;
  	}
  	if (lp->free + lp->dirty == c->leb_size &&
  	    !(lp->flags & LPROPS_INDEX)) {
  		lst->total_free  += lp->free;
  		lst->total_dirty += lp->dirty;
  		lst->total_dark  +=  ubifs_calc_dark(c, c->leb_size);
  		return LPT_SCAN_CONTINUE;
  	}
  
  	sleb = ubifs_scan(c, lnum, 0, buf, 0);
  	if (IS_ERR(sleb)) {
  		ret = PTR_ERR(sleb);
  		if (ret == -EUCLEAN) {
  			ubifs_dump_lprops(c);
  			ubifs_dump_budg(c, &c->bi);
  		}
  		goto out;
  	}
  
  	is_idx = -1;
  	list_for_each_entry(snod, &sleb->nodes, list) {
  		int found, level = 0;
  
  		cond_resched();
  
  		if (is_idx == -1)
  			is_idx = (snod->type == UBIFS_IDX_NODE) ? 1 : 0;
  
  		if (is_idx && snod->type != UBIFS_IDX_NODE) {
  			ubifs_err(c, "indexing node in data LEB %d:%d",
  				  lnum, snod->offs);
  			goto out_destroy;
  		}
  
  		if (snod->type == UBIFS_IDX_NODE) {
  			struct ubifs_idx_node *idx = snod->node;
  
  			key_read(c, ubifs_idx_key(c, idx), &snod->key);
  			level = le16_to_cpu(idx->level);
  		}
  
  		found = ubifs_tnc_has_node(c, &snod->key, level, lnum,
  					   snod->offs, is_idx);
  		if (found) {
  			if (found < 0)
  				goto out_destroy;
  			used += ALIGN(snod->len, 8);
  		}
  	}
  
  	free = c->leb_size - sleb->endpt;
  	dirty = sleb->endpt - used;
  
  	if (free > c->leb_size || free < 0 || dirty > c->leb_size ||
  	    dirty < 0) {
  		ubifs_err(c, "bad calculated accounting for LEB %d: free %d, dirty %d",
  			  lnum, free, dirty);
  		goto out_destroy;
  	}
  
  	if (lp->free + lp->dirty == c->leb_size &&
  	    free + dirty == c->leb_size)
  		if ((is_idx && !(lp->flags & LPROPS_INDEX)) ||
  		    (!is_idx && free == c->leb_size) ||
  		    lp->free == c->leb_size) {
  			/*
  			 * Empty or freeable LEBs could contain index
  			 * nodes from an uncompleted commit due to an
  			 * unclean unmount. Or they could be empty for
  			 * the same reason. Or it may simply not have been
  			 * unmapped.
  			 */
  			free = lp->free;
  			dirty = lp->dirty;
  			is_idx = 0;
  		    }
  
  	if (is_idx && lp->free + lp->dirty == free + dirty &&
  	    lnum != c->ihead_lnum) {
  		/*
  		 * After an unclean unmount, an index LEB could have a different
  		 * amount of free space than the value recorded by lprops. That
  		 * is because the in-the-gaps method may use free space or
  		 * create free space (as a side-effect of using ubi_leb_change
  		 * and not writing the whole LEB). The incorrect free space
  		 * value is not a problem because the index is only ever
  		 * allocated empty LEBs, so there will never be an attempt to
  		 * write to the free space at the end of an index LEB - except
  		 * by the in-the-gaps method for which it is not a problem.
  		 */
  		free = lp->free;
  		dirty = lp->dirty;
  	}
  
  	if (lp->free != free || lp->dirty != dirty)
  		goto out_print;
  
  	if (is_idx && !(lp->flags & LPROPS_INDEX)) {
  		if (free == c->leb_size)
  			/* Free but not unmapped LEB, it's fine */
  			is_idx = 0;
  		else {
  			ubifs_err(c, "indexing node without indexing flag");
  			goto out_print;
  		}
  	}
  
  	if (!is_idx && (lp->flags & LPROPS_INDEX)) {
  		ubifs_err(c, "data node with indexing flag");
  		goto out_print;
  	}
  
  	if (free == c->leb_size)
  		lst->empty_lebs += 1;
  
  	if (is_idx)
  		lst->idx_lebs += 1;
  
  	if (!(lp->flags & LPROPS_INDEX))
  		lst->total_used += c->leb_size - free - dirty;
  	lst->total_free += free;
  	lst->total_dirty += dirty;
  
  	if (!(lp->flags & LPROPS_INDEX)) {
  		int spc = free + dirty;
  
  		if (spc < c->dead_wm)
  			lst->total_dead += spc;
  		else
  			lst->total_dark += ubifs_calc_dark(c, spc);
  	}
  
  	ubifs_scan_destroy(sleb);
  	vfree(buf);
  	return LPT_SCAN_CONTINUE;
  
  out_print:
  	ubifs_err(c, "bad accounting of LEB %d: free %d, dirty %d flags %#x, should be free %d, dirty %d",
  		  lnum, lp->free, lp->dirty, lp->flags, free, dirty);
  	ubifs_dump_leb(c, lnum);
  out_destroy:
  	ubifs_scan_destroy(sleb);
  	ret = -EINVAL;
  out:
  	vfree(buf);
  	return ret;
  }
  
  /**
   * dbg_check_lprops - check all LEB properties.
   * @c: UBIFS file-system description object
   *
   * This function checks all LEB properties and makes sure they are all correct.
   * It returns zero if everything is fine, %-EINVAL if there is an inconsistency
   * and other negative error codes in case of other errors. This function is
   * called while the file system is locked (because of commit start), so no
   * additional locking is required. Note that locking the LPT mutex would cause
   * a circular lock dependency with the TNC mutex.
   */
  int dbg_check_lprops(struct ubifs_info *c)
  {
  	int i, err;
  	struct ubifs_lp_stats lst;
  
  	if (!dbg_is_chk_lprops(c))
  		return 0;
  
  	/*
  	 * As we are going to scan the media, the write buffers have to be
  	 * synchronized.
  	 */
  	for (i = 0; i < c->jhead_cnt; i++) {
  		err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
  		if (err)
  			return err;
  	}
  
  	memset(&lst, 0, sizeof(struct ubifs_lp_stats));
  	err = ubifs_lpt_scan_nolock(c, c->main_first, c->leb_cnt - 1,
  				    (ubifs_lpt_scan_callback)scan_check_cb,
  				    &lst);
  	if (err && err != -ENOSPC)
  		goto out;
  
  	if (lst.empty_lebs != c->lst.empty_lebs ||
  	    lst.idx_lebs != c->lst.idx_lebs ||
  	    lst.total_free != c->lst.total_free ||
  	    lst.total_dirty != c->lst.total_dirty ||
  	    lst.total_used != c->lst.total_used) {
  		ubifs_err(c, "bad overall accounting");
  		ubifs_err(c, "calculated: empty_lebs %d, idx_lebs %d, total_free %lld, total_dirty %lld, total_used %lld",
  			  lst.empty_lebs, lst.idx_lebs, lst.total_free,
  			  lst.total_dirty, lst.total_used);
  		ubifs_err(c, "read from lprops: empty_lebs %d, idx_lebs %d, total_free %lld, total_dirty %lld, total_used %lld",
  			  c->lst.empty_lebs, c->lst.idx_lebs, c->lst.total_free,
  			  c->lst.total_dirty, c->lst.total_used);
  		err = -EINVAL;
  		goto out;
  	}
  
  	if (lst.total_dead != c->lst.total_dead ||
  	    lst.total_dark != c->lst.total_dark) {
  		ubifs_err(c, "bad dead/dark space accounting");
  		ubifs_err(c, "calculated: total_dead %lld, total_dark %lld",
  			  lst.total_dead, lst.total_dark);
  		ubifs_err(c, "read from lprops: total_dead %lld, total_dark %lld",
  			  c->lst.total_dead, c->lst.total_dark);
  		err = -EINVAL;
  		goto out;
  	}
  
  	err = dbg_check_cats(c);
  out:
  	return err;
  }
  