p54: fix lm87 checksum endianness

[linux-2.6] / fs / ubifs / lprops.c

/*
 * 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 uncategorized */
                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;
}

/**
 * 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);
        }
}

/**
 * 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
 * uncategorized 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 recategorize
 *
 * LEB properties are categorized to enable fast find operations. When the LEB
 * properties change they must be recategorized.
 */
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 = &c->lpt_heap[new_cat - 1];

                /* 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);
        }
}

/**
 * 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 amount of dark space in an LEB which has @spc bytes
 * of free and dirty space. Returns the calculations result.
 *
 * Dark space is the space which is not always usable - it depends on which
 * nodes are written in which order. E.g., if an LEB has only 512 free bytes,
 * it is dark space, because it cannot fit a large data node. So UBIFS cannot
 * count on this LEB and treat these 512 bytes as usable because it is not true
 * if, for example, only big chunks of uncompressible data will be written to
 * the FS.
 */
static int calc_dark(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_ZNODE, &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. This function does not change a LEB
 * property (@free, @dirty or @flag) if the value passed is %LPROPS_NC.
 *
 * This function returns a pointer to the updated LEB properties on success
 * and a negative error code on failure. N.B. 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 -= 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 += 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 *st)
{
        spin_lock(&c->space_lock);
        memcpy(st, &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);
        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);
        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);
                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;
}

#ifdef CONFIG_UBIFS_FS_DEBUG

/**
 * 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 (!(ubifs_chk_flags & (UBIFS_CHK_GEN | UBIFS_CHK_LPROPS)))
                return 0;

        list_for_each_entry(lprops, &c->empty_list, list) {
                if (lprops->free != c->leb_size) {
                        ubifs_err("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("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("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("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("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("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("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("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("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("null ptr in LPT heap cat %d", cat);
                                return -EINVAL;
                        }
                        if (lprops->hpos != i) {
                                ubifs_err("bad ptr in LPT heap cat %d", cat);
                                return -EINVAL;
                        }
                        if (lprops->flags & LPROPS_TAKEN) {
                                ubifs_err("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 (!(ubifs_chk_flags & (UBIFS_CHK_GEN | UBIFS_CHK_LPROPS)))
                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) {
                        dbg_msg("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) {
                dbg_msg("failed cat %d hpos %d err %d", cat, i, err);
                dbg_dump_stack();
                dbg_dump_heap(c, heap, cat);
        }
}

/**
 * struct scan_check_data - data provided to scan callback function.
 * @lst: LEB properties statistics
 * @err: error code
 */
struct scan_check_data {
        struct ubifs_lp_stats lst;
        int err;
};

/**
 * 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
 * @data: information passed to and from the caller of the scan
 *
 * 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 scan_check_data *data)
{
        struct ubifs_scan_leb *sleb;
        struct ubifs_scan_node *snod;
        struct ubifs_lp_stats *lst = &data->lst;
        int cat, lnum = lp->lnum, is_idx = 0, used = 0, free, dirty;

        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("bad LEB category %d expected %d",
                                  (lp->flags & LPROPS_CAT_MASK), cat);
                        goto out;
                }
        }

        /* 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("bad LPT list (category %d)", cat);
                                goto out;
                        }
                }
        }

        /* 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("bad LPT heap (category %d)", cat);
                        goto out;
                }
        }

        sleb = ubifs_scan(c, lnum, 0, c->dbg_buf);
        if (IS_ERR(sleb)) {
                /*
                 * After an unclean unmount, empty and freeable LEBs
                 * may contain garbage.
                 */
                if (lp->free == c->leb_size) {
                        ubifs_err("scan errors were in empty LEB "
                                  "- continuing checking");
                        lst->empty_lebs += 1;
                        lst->total_free += c->leb_size;
                        lst->total_dark += calc_dark(c, c->leb_size);
                        return LPT_SCAN_CONTINUE;
                }

                if (lp->free + lp->dirty == c->leb_size &&
                    !(lp->flags & LPROPS_INDEX)) {
                        ubifs_err("scan errors were in freeable LEB "
                                  "- continuing checking");
                        lst->total_free  += lp->free;
                        lst->total_dirty += lp->dirty;
                        lst->total_dark  +=  calc_dark(c, c->leb_size);
                        return LPT_SCAN_CONTINUE;
                }
                data->err = PTR_ERR(sleb);
                return LPT_SCAN_STOP;
        }

        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("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("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("indexing node without indexing "
                                  "flag");
                        goto out_print;
                }
        }

        if (!is_idx && (lp->flags & LPROPS_INDEX)) {
                ubifs_err("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 += calc_dark(c, spc);
        }

        ubifs_scan_destroy(sleb);
        return LPT_SCAN_CONTINUE;

out_print:
        ubifs_err("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);
        dbg_dump_leb(c, lnum);
out_destroy:
        ubifs_scan_destroy(sleb);
out:
        data->err = -EINVAL;
        return LPT_SCAN_STOP;
}

/**
 * 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 scan_check_data data;
        struct ubifs_lp_stats *lst = &data.lst;

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

        data.err = 0;
        err = ubifs_lpt_scan_nolock(c, c->main_first, c->leb_cnt - 1,
                                    (ubifs_lpt_scan_callback)scan_check_cb,
                                    &data);
        if (err && err != -ENOSPC)
                goto out;
        if (data.err) {
                err = data.err;
                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("bad overall accounting");
                ubifs_err("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("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("bad dead/dark space accounting");
                ubifs_err("calculated: total_dead %lld, total_dark %lld",
                          lst->total_dead, lst->total_dark);
                ubifs_err("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;
}

#endif /* CONFIG_UBIFS_FS_DEBUG */