/*
 * 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 (@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 -= 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 *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);
        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;
}