/*
 * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
 *
 * Copyright (C) 2002-2011 Aleph One Ltd.
 *   for Toby Churchill Ltd and Brightstar Engineering
 *
 * Created by Charles Manning <charles@aleph1.co.uk>
 *
 * 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.
 */

#include "yaffs_guts.h"
#include "yaffs_trace.h"
#include "yaffs_yaffs2.h"
#include "yaffs_checkptrw.h"
#include "yaffs_bitmap.h"
#include "yaffs_nand.h"
#include "yaffs_getblockinfo.h"
#include "yaffs_verify.h"
#include "yaffs_attribs.h"
#include "yaffs_summary.h"

/*
 * Checkpoints are really no benefit on very small partitions.
 *
 * To save space on small partitions don't bother with checkpoints unless
 * the partition is at least this big.
 */
#define YAFFS_CHECKPOINT_MIN_BLOCKS 60
#define YAFFS_SMALL_HOLE_THRESHOLD 4

/*
 * Oldest Dirty Sequence Number handling.
 */

/* yaffs_calc_oldest_dirty_seq()
 * yaffs2_find_oldest_dirty_seq()
 * Calculate the oldest dirty sequence number if we don't know it.
 */
void yaffs_calc_oldest_dirty_seq(struct yaffs_dev *dev)
{
        int i;
        unsigned seq;
        unsigned block_no = 0;
        struct yaffs_block_info *b;

        if (!dev->param.is_yaffs2)
                return;

        /* Find the oldest dirty sequence number. */
        seq = dev->seq_number + 1;
        b = dev->block_info;
        for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
                if (b->block_state == YAFFS_BLOCK_STATE_FULL &&
                    (b->pages_in_use - b->soft_del_pages) <
                    dev->param.chunks_per_block &&
                    b->seq_number < seq) {
                        seq = b->seq_number;
                        block_no = i;
                }
                b++;
        }

        if (block_no) {
                dev->oldest_dirty_seq = seq;
                dev->oldest_dirty_block = block_no;
        }
}

void yaffs2_find_oldest_dirty_seq(struct yaffs_dev *dev)
{
        if (!dev->param.is_yaffs2)
                return;

        if (!dev->oldest_dirty_seq)
                yaffs_calc_oldest_dirty_seq(dev);
}

/*
 * yaffs_clear_oldest_dirty_seq()
 * Called when a block is erased or marked bad. (ie. when its seq_number
 * becomes invalid). If the value matches the oldest then we clear
 * dev->oldest_dirty_seq to force its recomputation.
 */
void yaffs2_clear_oldest_dirty_seq(struct yaffs_dev *dev,
                                   struct yaffs_block_info *bi)
{

        if (!dev->param.is_yaffs2)
                return;

        if (!bi || bi->seq_number == dev->oldest_dirty_seq) {
                dev->oldest_dirty_seq = 0;
                dev->oldest_dirty_block = 0;
        }
}

/*
 * yaffs2_update_oldest_dirty_seq()
 * Update the oldest dirty sequence number whenever we dirty a block.
 * Only do this if the oldest_dirty_seq is actually being tracked.
 */
void yaffs2_update_oldest_dirty_seq(struct yaffs_dev *dev, unsigned block_no,
                                    struct yaffs_block_info *bi)
{
        if (!dev->param.is_yaffs2)
                return;

        if (dev->oldest_dirty_seq) {
                if (dev->oldest_dirty_seq > bi->seq_number) {
                        dev->oldest_dirty_seq = bi->seq_number;
                        dev->oldest_dirty_block = block_no;
                }
        }
}

int yaffs_block_ok_for_gc(struct yaffs_dev *dev, struct yaffs_block_info *bi)
{

        if (!dev->param.is_yaffs2)
                return 1;       /* disqualification only applies to yaffs2. */

        if (!bi->has_shrink_hdr)
                return 1;       /* can gc */

        yaffs2_find_oldest_dirty_seq(dev);

        /* Can't do gc of this block if there are any blocks older than this
         * one that have discarded pages.
         */
        return (bi->seq_number <= dev->oldest_dirty_seq);
}

/*
 * yaffs2_find_refresh_block()
 * periodically finds the oldest full block by sequence number for refreshing.
 * Only for yaffs2.
 */
u32 yaffs2_find_refresh_block(struct yaffs_dev *dev)
{
        u32 b;
        u32 oldest = 0;
        u32 oldest_seq = 0;
        struct yaffs_block_info *bi;

        if (!dev->param.is_yaffs2)
                return oldest;

        /*
         * If refresh period < 10 then refreshing is disabled.
         */
        if (dev->param.refresh_period < 10)
                return oldest;

        /*
         * Fix broken values.
         */
        if (dev->refresh_skip > dev->param.refresh_period)
                dev->refresh_skip = dev->param.refresh_period;

        if (dev->refresh_skip > 0)
                return oldest;

        /*
         * Refresh skip is now zero.
         * We'll do a refresh this time around....
         * Update the refresh skip and find the oldest block.
         */
        dev->refresh_skip = dev->param.refresh_period;
        dev->refresh_count++;
        bi = dev->block_info;
        for (b = dev->internal_start_block; b <= dev->internal_end_block; b++) {

                if (bi->block_state == YAFFS_BLOCK_STATE_FULL) {

                        if (oldest < 1 || bi->seq_number < oldest_seq) {
                                oldest = b;
                                oldest_seq = bi->seq_number;
                        }
                }
                bi++;
        }

        if (oldest > 0) {
                yaffs_trace(YAFFS_TRACE_GC,
                        "GC refresh count %d selected block %d with seq_number %d",
                        dev->refresh_count, oldest, oldest_seq);
        }

        return oldest;
}

int yaffs2_checkpt_required(struct yaffs_dev *dev)
{
        int nblocks;

        if (!dev->param.is_yaffs2)
                return 0;

        nblocks = dev->internal_end_block - dev->internal_start_block + 1;

        return !dev->param.skip_checkpt_wr &&
            !dev->read_only && (nblocks >= YAFFS_CHECKPOINT_MIN_BLOCKS);
}

int yaffs_calc_checkpt_blocks_required(struct yaffs_dev *dev)
{
        int retval;
        int n_bytes = 0;
        int n_blocks;
        int dev_blocks;

        if (!dev->param.is_yaffs2)
                return 0;

        if (!dev->checkpoint_blocks_required && yaffs2_checkpt_required(dev)) {
                /* Not a valid value so recalculate */
                dev_blocks = dev->param.end_block - dev->param.start_block + 1;
                n_bytes += sizeof(struct yaffs_checkpt_validity);
                n_bytes += sizeof(struct yaffs_checkpt_dev);
                n_bytes += dev_blocks * sizeof(struct yaffs_block_info);
                n_bytes += dev_blocks * dev->chunk_bit_stride;
                n_bytes +=
                    (sizeof(struct yaffs_checkpt_obj) + sizeof(u32)) *
                    dev->n_obj;
                n_bytes += (dev->tnode_size + sizeof(u32)) * dev->n_tnodes;
                n_bytes += sizeof(struct yaffs_checkpt_validity);
                n_bytes += sizeof(u32); /* checksum */

                /* Round up and add 2 blocks to allow for some bad blocks,
                 * so add 3 */

                n_blocks =
                    (n_bytes /
                     (dev->data_bytes_per_chunk *
                      dev->param.chunks_per_block)) + 3;

                dev->checkpoint_blocks_required = n_blocks;
        }

        retval = dev->checkpoint_blocks_required - dev->blocks_in_checkpt;
        if (retval < 0)
                retval = 0;
        return retval;
}

/*--------------------- Checkpointing --------------------*/

static int yaffs2_wr_checkpt_validity_marker(struct yaffs_dev *dev, int head)
{
        struct yaffs_checkpt_validity cp;

        memset(&cp, 0, sizeof(cp));

        cp.struct_type = sizeof(cp);
        cp.magic = YAFFS_MAGIC;
        cp.version = YAFFS_CHECKPOINT_VERSION;
        cp.head = (head) ? 1 : 0;

        return (yaffs2_checkpt_wr(dev, &cp, sizeof(cp)) == sizeof(cp)) ? 1 : 0;
}

static int yaffs2_rd_checkpt_validity_marker(struct yaffs_dev *dev, int head)
{
        struct yaffs_checkpt_validity cp;
        int ok;

        ok = (yaffs2_checkpt_rd(dev, &cp, sizeof(cp)) == sizeof(cp));

        if (ok)
                ok = (cp.struct_type == sizeof(cp)) &&
                    (cp.magic == YAFFS_MAGIC) &&
                    (cp.version == YAFFS_CHECKPOINT_VERSION) &&
                    (cp.head == ((head) ? 1 : 0));
        return ok ? 1 : 0;
}

static void yaffs2_dev_to_checkpt_dev(struct yaffs_checkpt_dev *cp,
                                      struct yaffs_dev *dev)
{
        cp->n_erased_blocks = dev->n_erased_blocks;
        cp->alloc_block = dev->alloc_block;
        cp->alloc_page = dev->alloc_page;
        cp->n_free_chunks = dev->n_free_chunks;

        cp->n_deleted_files = dev->n_deleted_files;
        cp->n_unlinked_files = dev->n_unlinked_files;
        cp->n_bg_deletions = dev->n_bg_deletions;
        cp->seq_number = dev->seq_number;

}

static void yaffs_checkpt_dev_to_dev(struct yaffs_dev *dev,
                                     struct yaffs_checkpt_dev *cp)
{
        dev->n_erased_blocks = cp->n_erased_blocks;
        dev->alloc_block = cp->alloc_block;
        dev->alloc_page = cp->alloc_page;
        dev->n_free_chunks = cp->n_free_chunks;

        dev->n_deleted_files = cp->n_deleted_files;
        dev->n_unlinked_files = cp->n_unlinked_files;
        dev->n_bg_deletions = cp->n_bg_deletions;
        dev->seq_number = cp->seq_number;
}

static int yaffs2_wr_checkpt_dev(struct yaffs_dev *dev)
{
        struct yaffs_checkpt_dev cp;
        u32 n_bytes;
        u32 n_blocks = dev->internal_end_block - dev->internal_start_block + 1;
        int ok;

        /* Write device runtime values */
        yaffs2_dev_to_checkpt_dev(&cp, dev);
        cp.struct_type = sizeof(cp);

        ok = (yaffs2_checkpt_wr(dev, &cp, sizeof(cp)) == sizeof(cp));
        if (!ok)
                return 0;

        /* Write block info */
        n_bytes = n_blocks * sizeof(struct yaffs_block_info);
        ok = (yaffs2_checkpt_wr(dev, dev->block_info, n_bytes) == n_bytes);
        if (!ok)
                return 0;

        /* Write chunk bits */
        n_bytes = n_blocks * dev->chunk_bit_stride;
        ok = (yaffs2_checkpt_wr(dev, dev->chunk_bits, n_bytes) == n_bytes);

        return ok ? 1 : 0;
}

static int yaffs2_rd_checkpt_dev(struct yaffs_dev *dev)
{
        struct yaffs_checkpt_dev cp;
        u32 n_bytes;
        u32 n_blocks =
            (dev->internal_end_block - dev->internal_start_block + 1);
        int ok;

        ok = (yaffs2_checkpt_rd(dev, &cp, sizeof(cp)) == sizeof(cp));
        if (!ok)
                return 0;

        if (cp.struct_type != sizeof(cp))
                return 0;

        yaffs_checkpt_dev_to_dev(dev, &cp);

        n_bytes = n_blocks * sizeof(struct yaffs_block_info);

        ok = (yaffs2_checkpt_rd(dev, dev->block_info, n_bytes) == n_bytes);

        if (!ok)
                return 0;

        n_bytes = n_blocks * dev->chunk_bit_stride;

        ok = (yaffs2_checkpt_rd(dev, dev->chunk_bits, n_bytes) == n_bytes);

        return ok ? 1 : 0;
}

static void yaffs2_obj_checkpt_obj(struct yaffs_checkpt_obj *cp,
                                   struct yaffs_obj *obj)
{
        cp->obj_id = obj->obj_id;
        cp->parent_id = (obj->parent) ? obj->parent->obj_id : 0;
        cp->hdr_chunk = obj->hdr_chunk;
        cp->variant_type = obj->variant_type;
        cp->deleted = obj->deleted;
        cp->soft_del = obj->soft_del;
        cp->unlinked = obj->unlinked;
        cp->fake = obj->fake;
        cp->rename_allowed = obj->rename_allowed;
        cp->unlink_allowed = obj->unlink_allowed;
        cp->serial = obj->serial;
        cp->n_data_chunks = obj->n_data_chunks;

        if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE)
                cp->size_or_equiv_obj = obj->variant.file_variant.file_size;
        else if (obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK)
                cp->size_or_equiv_obj = obj->variant.hardlink_variant.equiv_id;
}

static int yaffs2_checkpt_obj_to_obj(struct yaffs_obj *obj,
                                     struct yaffs_checkpt_obj *cp)
{
        struct yaffs_obj *parent;

        if (obj->variant_type != cp->variant_type) {
                yaffs_trace(YAFFS_TRACE_ERROR,
                        "Checkpoint read object %d type %d chunk %d does not match existing object type %d",
                        cp->obj_id, cp->variant_type, cp->hdr_chunk,
                        obj->variant_type);
                return 0;
        }

        obj->obj_id = cp->obj_id;

        if (cp->parent_id)
                parent = yaffs_find_or_create_by_number(obj->my_dev,
                                                cp->parent_id,
                                                YAFFS_OBJECT_TYPE_DIRECTORY);
        else
                parent = NULL;

        if (parent) {
                if (parent->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
                        yaffs_trace(YAFFS_TRACE_ALWAYS,
                                "Checkpoint read object %d parent %d type %d chunk %d Parent type, %d, not directory",
                                cp->obj_id, cp->parent_id,
                                cp->variant_type, cp->hdr_chunk,
                                parent->variant_type);
                        return 0;
                }
                yaffs_add_obj_to_dir(parent, obj);
        }

        obj->hdr_chunk = cp->hdr_chunk;
        obj->variant_type = cp->variant_type;
        obj->deleted = cp->deleted;
        obj->soft_del = cp->soft_del;
        obj->unlinked = cp->unlinked;
        obj->fake = cp->fake;
        obj->rename_allowed = cp->rename_allowed;
        obj->unlink_allowed = cp->unlink_allowed;
        obj->serial = cp->serial;
        obj->n_data_chunks = cp->n_data_chunks;

        if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE)
                obj->variant.file_variant.file_size = cp->size_or_equiv_obj;
        else if (obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK)
                obj->variant.hardlink_variant.equiv_id = cp->size_or_equiv_obj;

        if (obj->hdr_chunk > 0)
                obj->lazy_loaded = 1;
        return 1;
}

static int yaffs2_checkpt_tnode_worker(struct yaffs_obj *in,
                                       struct yaffs_tnode *tn, u32 level,
                                       int chunk_offset)
{
        int i;
        struct yaffs_dev *dev = in->my_dev;
        int ok = 1;
        u32 base_offset;

        if (!tn)
                return 1;

        if (level > 0) {
                for (i = 0; i < YAFFS_NTNODES_INTERNAL && ok; i++) {
                        if (!tn->internal[i])
                                continue;
                        ok = yaffs2_checkpt_tnode_worker(in,
                                 tn->internal[i],
                                 level - 1,
                                 (chunk_offset <<
                                  YAFFS_TNODES_INTERNAL_BITS) + i);
                }
                return ok;
        }

        /* Level 0 tnode */
        base_offset = chunk_offset << YAFFS_TNODES_LEVEL0_BITS;
        ok = (yaffs2_checkpt_wr(dev, &base_offset, sizeof(base_offset)) ==
                        sizeof(base_offset));
        if (ok)
                ok = (yaffs2_checkpt_wr(dev, tn, dev->tnode_size) ==
                        dev->tnode_size);

        return ok;
}

static int yaffs2_wr_checkpt_tnodes(struct yaffs_obj *obj)
{
        u32 end_marker = ~0;
        int ok = 1;

        if (obj->variant_type != YAFFS_OBJECT_TYPE_FILE)
                return ok;

        ok = yaffs2_checkpt_tnode_worker(obj,
                                         obj->variant.file_variant.top,
                                         obj->variant.file_variant.
                                         top_level, 0);
        if (ok)
                ok = (yaffs2_checkpt_wr(obj->my_dev, &end_marker,
                                sizeof(end_marker)) == sizeof(end_marker));

        return ok ? 1 : 0;
}

static int yaffs2_rd_checkpt_tnodes(struct yaffs_obj *obj)
{
        u32 base_chunk;
        int ok = 1;
        struct yaffs_dev *dev = obj->my_dev;
        struct yaffs_file_var *file_stuct_ptr = &obj->variant.file_variant;
        struct yaffs_tnode *tn;
        int nread = 0;

        ok = (yaffs2_checkpt_rd(dev, &base_chunk, sizeof(base_chunk)) ==
              sizeof(base_chunk));

        while (ok && (~base_chunk)) {
                nread++;
                /* Read level 0 tnode */

                tn = yaffs_get_tnode(dev);
                if (tn)
                        ok = (yaffs2_checkpt_rd(dev, tn, dev->tnode_size) ==
                                dev->tnode_size);
                else
                        ok = 0;

                if (tn && ok)
                        ok = yaffs_add_find_tnode_0(dev,
                                                    file_stuct_ptr,
                                                    base_chunk, tn) ? 1 : 0;

                if (ok)
                        ok = (yaffs2_checkpt_rd
                              (dev, &base_chunk,
                               sizeof(base_chunk)) == sizeof(base_chunk));
        }

        yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                "Checkpoint read tnodes %d records, last %d. ok %d",
                nread, base_chunk, ok);

        return ok ? 1 : 0;
}

static int yaffs2_wr_checkpt_objs(struct yaffs_dev *dev)
{
        struct yaffs_obj *obj;
        struct yaffs_checkpt_obj cp;
        int i;
        int ok = 1;
        struct list_head *lh;

        /* Iterate through the objects in each hash entry,
         * dumping them to the checkpointing stream.
         */

        for (i = 0; ok && i < YAFFS_NOBJECT_BUCKETS; i++) {
                list_for_each(lh, &dev->obj_bucket[i].list) {
                        obj = list_entry(lh, struct yaffs_obj, hash_link);
                        if (!obj->defered_free) {
                                yaffs2_obj_checkpt_obj(&cp, obj);
                                cp.struct_type = sizeof(cp);

                                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                                        "Checkpoint write object %d parent %d type %d chunk %d obj addr %p",
                                        cp.obj_id, cp.parent_id,
                                        cp.variant_type, cp.hdr_chunk, obj);

                                ok = (yaffs2_checkpt_wr(dev, &cp,
                                                sizeof(cp)) == sizeof(cp));

                                if (ok &&
                                        obj->variant_type ==
                                        YAFFS_OBJECT_TYPE_FILE)
                                        ok = yaffs2_wr_checkpt_tnodes(obj);
                        }
                }
        }

        /* Dump end of list */
        memset(&cp, 0xff, sizeof(struct yaffs_checkpt_obj));
        cp.struct_type = sizeof(cp);

        if (ok)
                ok = (yaffs2_checkpt_wr(dev, &cp, sizeof(cp)) == sizeof(cp));

        return ok ? 1 : 0;
}

static int yaffs2_rd_checkpt_objs(struct yaffs_dev *dev)
{
        struct yaffs_obj *obj;
        struct yaffs_checkpt_obj cp;
        int ok = 1;
        int done = 0;
        LIST_HEAD(hard_list);


        while (ok && !done) {
                ok = (yaffs2_checkpt_rd(dev, &cp, sizeof(cp)) == sizeof(cp));
                if (cp.struct_type != sizeof(cp)) {
                        yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                                "struct size %d instead of %d ok %d",
                                cp.struct_type, (int)sizeof(cp), ok);
                        ok = 0;
                }

                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "Checkpoint read object %d parent %d type %d chunk %d ",
                        cp.obj_id, cp.parent_id, cp.variant_type,
                        cp.hdr_chunk);

                if (ok && cp.obj_id == ~0) {
                        done = 1;
                } else if (ok) {
                        obj =
                            yaffs_find_or_create_by_number(dev, cp.obj_id,
                                                           cp.variant_type);
                        if (obj) {
                                ok = yaffs2_checkpt_obj_to_obj(obj, &cp);
                                if (!ok)
                                        break;
                                if (obj->variant_type ==
                                        YAFFS_OBJECT_TYPE_FILE) {
                                        ok = yaffs2_rd_checkpt_tnodes(obj);
                                } else if (obj->variant_type ==
                                        YAFFS_OBJECT_TYPE_HARDLINK) {
                                        list_add(&obj->hard_links, &hard_list);
                                }
                        } else {
                                ok = 0;
                        }
                }
        }

        if (ok)
                yaffs_link_fixup(dev, &hard_list);

        return ok ? 1 : 0;
}

static int yaffs2_wr_checkpt_sum(struct yaffs_dev *dev)
{
        u32 checkpt_sum;
        int ok;

        yaffs2_get_checkpt_sum(dev, &checkpt_sum);

        ok = (yaffs2_checkpt_wr(dev, &checkpt_sum, sizeof(checkpt_sum)) ==
                sizeof(checkpt_sum));

        if (!ok)
                return 0;

        return 1;
}

static int yaffs2_rd_checkpt_sum(struct yaffs_dev *dev)
{
        u32 checkpt_sum0;
        u32 checkpt_sum1;
        int ok;

        yaffs2_get_checkpt_sum(dev, &checkpt_sum0);

        ok = (yaffs2_checkpt_rd(dev, &checkpt_sum1, sizeof(checkpt_sum1)) ==
                sizeof(checkpt_sum1));

        if (!ok)
                return 0;

        if (checkpt_sum0 != checkpt_sum1)
                return 0;

        return 1;
}

static int yaffs2_wr_checkpt_data(struct yaffs_dev *dev)
{
        int ok = 1;

        if (!yaffs2_checkpt_required(dev)) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "skipping checkpoint write");
                ok = 0;
        }

        if (ok)
                ok = yaffs2_checkpt_open(dev, 1);

        if (ok) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "write checkpoint validity");
                ok = yaffs2_wr_checkpt_validity_marker(dev, 1);
        }
        if (ok) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "write checkpoint device");
                ok = yaffs2_wr_checkpt_dev(dev);
        }
        if (ok) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "write checkpoint objects");
                ok = yaffs2_wr_checkpt_objs(dev);
        }
        if (ok) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "write checkpoint validity");
                ok = yaffs2_wr_checkpt_validity_marker(dev, 0);
        }

        if (ok)
                ok = yaffs2_wr_checkpt_sum(dev);

        if (!yaffs_checkpt_close(dev))
                ok = 0;

        if (ok)
                dev->is_checkpointed = 1;
        else
                dev->is_checkpointed = 0;

        return dev->is_checkpointed;
}

static int yaffs2_rd_checkpt_data(struct yaffs_dev *dev)
{
        int ok = 1;

        if (!dev->param.is_yaffs2)
                ok = 0;

        if (ok && dev->param.skip_checkpt_rd) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "skipping checkpoint read");
                ok = 0;
        }

        if (ok)
                ok = yaffs2_checkpt_open(dev, 0); /* open for read */

        if (ok) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "read checkpoint validity");
                ok = yaffs2_rd_checkpt_validity_marker(dev, 1);
        }
        if (ok) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "read checkpoint device");
                ok = yaffs2_rd_checkpt_dev(dev);
        }
        if (ok) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "read checkpoint objects");
                ok = yaffs2_rd_checkpt_objs(dev);
        }
        if (ok) {
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "read checkpoint validity");
                ok = yaffs2_rd_checkpt_validity_marker(dev, 0);
        }

        if (ok) {
                ok = yaffs2_rd_checkpt_sum(dev);
                yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                        "read checkpoint checksum %d", ok);
        }

        if (!yaffs_checkpt_close(dev))
                ok = 0;

        if (ok)
                dev->is_checkpointed = 1;
        else
                dev->is_checkpointed = 0;

        return ok ? 1 : 0;
}

void yaffs2_checkpt_invalidate(struct yaffs_dev *dev)
{
        if (dev->is_checkpointed || dev->blocks_in_checkpt > 0) {
                dev->is_checkpointed = 0;
                yaffs2_checkpt_invalidate_stream(dev);
        }
        if (dev->param.sb_dirty_fn)
                dev->param.sb_dirty_fn(dev);
}

int yaffs_checkpoint_save(struct yaffs_dev *dev)
{
        yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                "save entry: is_checkpointed %d",
                dev->is_checkpointed);

        yaffs_verify_objects(dev);
        yaffs_verify_blocks(dev);
        yaffs_verify_free_chunks(dev);

        if (!dev->is_checkpointed) {
                yaffs2_checkpt_invalidate(dev);
                yaffs2_wr_checkpt_data(dev);
        }

        yaffs_trace(YAFFS_TRACE_CHECKPOINT | YAFFS_TRACE_MOUNT,
                "save exit: is_checkpointed %d",
                dev->is_checkpointed);

        return dev->is_checkpointed;
}

int yaffs2_checkpt_restore(struct yaffs_dev *dev)
{
        int retval;

        yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                "restore entry: is_checkpointed %d",
                dev->is_checkpointed);

        retval = yaffs2_rd_checkpt_data(dev);

        if (dev->is_checkpointed) {
                yaffs_verify_objects(dev);
                yaffs_verify_blocks(dev);
                yaffs_verify_free_chunks(dev);
        }

        yaffs_trace(YAFFS_TRACE_CHECKPOINT,
                "restore exit: is_checkpointed %d",
                dev->is_checkpointed);

        return retval;
}

int yaffs2_handle_hole(struct yaffs_obj *obj, loff_t new_size)
{
        /* if new_size > old_file_size.
         * We're going to be writing a hole.
         * If the hole is small then write zeros otherwise write a start
         * of hole marker.
         */
        loff_t old_file_size;
        loff_t increase;
        int small_hole;
        int result = YAFFS_OK;
        struct yaffs_dev *dev = NULL;
        u8 *local_buffer = NULL;
        int small_increase_ok = 0;

        if (!obj)
                return YAFFS_FAIL;

        if (obj->variant_type != YAFFS_OBJECT_TYPE_FILE)
                return YAFFS_FAIL;

        dev = obj->my_dev;

        /* Bail out if not yaffs2 mode */
        if (!dev->param.is_yaffs2)
                return YAFFS_OK;

        old_file_size = obj->variant.file_variant.file_size;

        if (new_size <= old_file_size)
                return YAFFS_OK;

        increase = new_size - old_file_size;

        if (increase < YAFFS_SMALL_HOLE_THRESHOLD * dev->data_bytes_per_chunk &&
            yaffs_check_alloc_available(dev, YAFFS_SMALL_HOLE_THRESHOLD + 1))
                small_hole = 1;
        else
                small_hole = 0;

        if (small_hole)
                local_buffer = yaffs_get_temp_buffer(dev);

        if (local_buffer) {
                /* fill hole with zero bytes */
                loff_t pos = old_file_size;
                int this_write;
                int written;
                memset(local_buffer, 0, dev->data_bytes_per_chunk);
                small_increase_ok = 1;

                while (increase > 0 && small_increase_ok) {
                        this_write = increase;
                        if (this_write > dev->data_bytes_per_chunk)
                                this_write = dev->data_bytes_per_chunk;
                        written =
                            yaffs_do_file_wr(obj, local_buffer, pos, this_write,
                                             0);
                        if (written == this_write) {
                                pos += this_write;
                                increase -= this_write;
                        } else {
                                small_increase_ok = 0;
                        }
                }

                yaffs_release_temp_buffer(dev, local_buffer);

                /* If out of space then reverse any chunks we've added */
                if (!small_increase_ok)
                        yaffs_resize_file_down(obj, old_file_size);
        }

        if (!small_increase_ok &&
            obj->parent &&
            obj->parent->obj_id != YAFFS_OBJECTID_UNLINKED &&
            obj->parent->obj_id != YAFFS_OBJECTID_DELETED) {
                /* Write a hole start header with the old file size */
                yaffs_update_oh(obj, NULL, 0, 1, 0, NULL);
        }

        return result;
}

struct yaffs_block_index {
        int seq;
        int block;
};

static int yaffs2_ybicmp(const void *a, const void *b)
{
        int aseq = ((struct yaffs_block_index *)a)->seq;
        int bseq = ((struct yaffs_block_index *)b)->seq;
        int ablock = ((struct yaffs_block_index *)a)->block;
        int bblock = ((struct yaffs_block_index *)b)->block;

        if (aseq == bseq)
                return ablock - bblock;

        return aseq - bseq;
}

static inline int yaffs2_scan_chunk(struct yaffs_dev *dev,
                struct yaffs_block_info *bi,
                int blk, int chunk_in_block,
                int *found_chunks,
                u8 *chunk_data,
                struct list_head *hard_list,
                int summary_available)
{
        struct yaffs_obj_hdr *oh;
        struct yaffs_obj *in;
        struct yaffs_obj *parent;
        int equiv_id;
        loff_t file_size;
        int is_shrink;
        int is_unlinked;
        struct yaffs_ext_tags tags;
        int alloc_failed = 0;
        int chunk = blk * dev->param.chunks_per_block + chunk_in_block;
        struct yaffs_file_var *file_var;
        struct yaffs_hardlink_var *hl_var;
        struct yaffs_symlink_var *sl_var;

        if (summary_available) {
                yaffs_summary_fetch(dev, &tags, chunk_in_block);
                tags.seq_number = bi->seq_number;
        }

        if (!summary_available || tags.obj_id == 0) {
                yaffs_rd_chunk_tags_nand(dev, chunk, NULL, &tags);
                dev->tags_used++;
        } else {
                dev->summary_used++;
        }

        /* Let's have a good look at this chunk... */

        if (!tags.chunk_used) {
                /* An unassigned chunk in the block.
                 * If there are used chunks after this one, then
                 * it is a chunk that was skipped due to failing
                 * the erased check. Just skip it so that it can
                 * be deleted.
                 * But, more typically, We get here when this is
                 * an unallocated chunk and his means that
                 * either the block is empty or this is the one
                 * being allocated from
                 */

                if (*found_chunks) {
                        /* This is a chunk that was skipped due
                         * to failing the erased check */
                } else if (chunk_in_block == 0) {
                        /* We're looking at the first chunk in
                         * the block so the block is unused */
                        bi->block_state = YAFFS_BLOCK_STATE_EMPTY;
                        dev->n_erased_blocks++;
                } else {
                        if (bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCAN ||
                            bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING) {
                                if (dev->seq_number == bi->seq_number) {
                                        /* Allocating from this block*/
                                        yaffs_trace(YAFFS_TRACE_SCAN,
                                            " Allocating from %d %d",
                                            blk, chunk_in_block);

                                        bi->block_state =
                                                YAFFS_BLOCK_STATE_ALLOCATING;
                                        dev->alloc_block = blk;

                                        dev->alloc_page = chunk_in_block;
                                        dev->alloc_block_finder = blk;
                                } else {
                                        /* This is a partially written block
                                         * that is not the current
                                         * allocation block.
                                         */
                                        yaffs_trace(YAFFS_TRACE_SCAN,
                                                "Partially written block %d detected. gc will fix this.",
                                                blk);
                                }
                        }
                }

                dev->n_free_chunks++;

        } else if (tags.ecc_result ==
                YAFFS_ECC_RESULT_UNFIXED) {
                yaffs_trace(YAFFS_TRACE_SCAN,
                        " Unfixed ECC in chunk(%d:%d), chunk ignored",
                        blk, chunk_in_block);
                        dev->n_free_chunks++;
        } else if (tags.obj_id > YAFFS_MAX_OBJECT_ID ||
                   tags.chunk_id > YAFFS_MAX_CHUNK_ID ||
                   tags.obj_id == YAFFS_OBJECTID_SUMMARY ||
                   (tags.chunk_id > 0 &&
                     tags.n_bytes > dev->data_bytes_per_chunk) ||
                   tags.seq_number != bi->seq_number) {
                yaffs_trace(YAFFS_TRACE_SCAN,
                        "Chunk (%d:%d) with bad tags:obj = %d, chunk_id = %d, n_bytes = %d, ignored",
                        blk, chunk_in_block, tags.obj_id,
                        tags.chunk_id, tags.n_bytes);
                dev->n_free_chunks++;
        } else if (tags.chunk_id > 0) {
                /* chunk_id > 0 so it is a data chunk... */
                loff_t endpos;
                loff_t chunk_base = (tags.chunk_id - 1) *
                                        dev->data_bytes_per_chunk;

                *found_chunks = 1;

                yaffs_set_chunk_bit(dev, blk, chunk_in_block);
                bi->pages_in_use++;

                in = yaffs_find_or_create_by_number(dev,
                                        tags.obj_id,
                                        YAFFS_OBJECT_TYPE_FILE);
                if (!in)
                        /* Out of memory */
                        alloc_failed = 1;

                if (in &&
                    in->variant_type == YAFFS_OBJECT_TYPE_FILE &&
                    chunk_base < in->variant.file_variant.shrink_size) {
                        /* This has not been invalidated by
                         * a resize */
                        if (!yaffs_put_chunk_in_file(in, tags.chunk_id,
                                                                chunk, -1))
                                alloc_failed = 1;

                        /* File size is calculated by looking at
                         * the data chunks if we have not
                         * seen an object header yet.
                         * Stop this practice once we find an
                         * object header.
                         */
                        endpos = chunk_base + tags.n_bytes;

                        if (!in->valid &&
                            in->variant.file_variant.scanned_size < endpos) {
                                in->variant.file_variant.
                                    scanned_size = endpos;
                                in->variant.file_variant.
                                    file_size = endpos;
                        }
                } else if (in) {
                        /* This chunk has been invalidated by a
                         * resize, or a past file deletion
                         * so delete the chunk*/
                        yaffs_chunk_del(dev, chunk, 1, __LINE__);
                }
        } else {
                /* chunk_id == 0, so it is an ObjectHeader.
                 * Thus, we read in the object header and make
                 * the object
                 */
                *found_chunks = 1;

                yaffs_set_chunk_bit(dev, blk, chunk_in_block);
                bi->pages_in_use++;

                oh = NULL;
                in = NULL;

                if (tags.extra_available) {
                        in = yaffs_find_or_create_by_number(dev,
                                        tags.obj_id,
                                        tags.extra_obj_type);
                        if (!in)
                                alloc_failed = 1;
                }

                if (!in ||
                    (!in->valid && dev->param.disable_lazy_load) ||
                    tags.extra_shadows ||
                    (!in->valid && (tags.obj_id == YAFFS_OBJECTID_ROOT ||
                                 tags.obj_id == YAFFS_OBJECTID_LOSTNFOUND))) {

                        /* If we don't have  valid info then we
                         * need to read the chunk
                         * TODO In future we can probably defer
                         * reading the chunk and living with
                         * invalid data until needed.
                         */

                        yaffs_rd_chunk_tags_nand(dev, chunk, chunk_data, NULL);

                        oh = (struct yaffs_obj_hdr *)chunk_data;

                        if (dev->param.inband_tags) {
                                /* Fix up the header if they got
                                 * corrupted by inband tags */
                                oh->shadows_obj =
                                    oh->inband_shadowed_obj_id;
                                oh->is_shrink =
                                    oh->inband_is_shrink;
                        }

                        if (!in) {
                                in = yaffs_find_or_create_by_number(dev,
                                                        tags.obj_id, oh->type);
                                if (!in)
                                        alloc_failed = 1;
                        }
                }

                if (!in) {
                        /* TODO Hoosterman we have a problem! */
                        yaffs_trace(YAFFS_TRACE_ERROR,
                                "yaffs tragedy: Could not make object for object  %d at chunk %d during scan",
                                tags.obj_id, chunk);
                        return YAFFS_FAIL;
                }

                if (in->valid) {
                        /* We have already filled this one.
                         * We have a duplicate that will be
                         * discarded, but we first have to suck
                         * out resize info if it is a file.
                         */
                        if ((in->variant_type == YAFFS_OBJECT_TYPE_FILE) &&
                                ((oh && oh->type == YAFFS_OBJECT_TYPE_FILE) ||
                                 (tags.extra_available &&
                                  tags.extra_obj_type == YAFFS_OBJECT_TYPE_FILE)
                                )) {
                                loff_t this_size = (oh) ?
                                        yaffs_oh_to_size(oh) :
                                        tags.extra_file_size;
                                u32 parent_obj_id = (oh) ?
                                        oh->parent_obj_id :
                                        tags.extra_parent_id;

                                is_shrink = (oh) ?
                                        oh->is_shrink :
                                        tags.extra_is_shrink;

                                /* If it is deleted (unlinked
                                 * at start also means deleted)
                                 * we treat the file size as
                                 * being zeroed at this point.
                                 */
                                if (parent_obj_id == YAFFS_OBJECTID_DELETED ||
                                    parent_obj_id == YAFFS_OBJECTID_UNLINKED) {
                                        this_size = 0;
                                        is_shrink = 1;
                                }

                                if (is_shrink &&
                                    in->variant.file_variant.shrink_size >
                                    this_size)
                                        in->variant.file_variant.shrink_size =
                                        this_size;

                                if (is_shrink)
                                        bi->has_shrink_hdr = 1;
                        }
                        /* Use existing - destroy this one. */
                        yaffs_chunk_del(dev, chunk, 1, __LINE__);
                }

                if (!in->valid && in->variant_type !=
                    (oh ? oh->type : tags.extra_obj_type))
                        yaffs_trace(YAFFS_TRACE_ERROR,
                                "yaffs tragedy: Bad object type, %d != %d, for object %d at chunk %d during scan",
                                oh ? oh->type : tags.extra_obj_type,
                                in->variant_type, tags.obj_id,
                                chunk);

                if (!in->valid &&
                    (tags.obj_id == YAFFS_OBJECTID_ROOT ||
                     tags.obj_id == YAFFS_OBJECTID_LOSTNFOUND)) {
                        /* We only load some info, don't fiddle
                         * with directory structure */
                        in->valid = 1;

                        if (oh) {
                                in->yst_mode = oh->yst_mode;
                                yaffs_load_attribs(in, oh);
                                in->lazy_loaded = 0;
                        } else {
                                in->lazy_loaded = 1;
                        }
                        in->hdr_chunk = chunk;

                } else if (!in->valid) {
                        /* we need to load this info */
                        in->valid = 1;
                        in->hdr_chunk = chunk;
                        if (oh) {
                                in->variant_type = oh->type;
                                in->yst_mode = oh->yst_mode;
                                yaffs_load_attribs(in, oh);

                                if (oh->shadows_obj > 0)
                                        yaffs_handle_shadowed_obj(dev,
                                             oh->shadows_obj, 1);

                                yaffs_set_obj_name_from_oh(in, oh);
                                parent = yaffs_find_or_create_by_number(dev,
                                                oh->parent_obj_id,
                                                YAFFS_OBJECT_TYPE_DIRECTORY);
                                file_size = yaffs_oh_to_size(oh);
                                is_shrink = oh->is_shrink;
                                equiv_id = oh->equiv_id;
                        } else {
                                in->variant_type = tags.extra_obj_type;
                                parent = yaffs_find_or_create_by_number(dev,
                                                tags.extra_parent_id,
                                                YAFFS_OBJECT_TYPE_DIRECTORY);
                                file_size = tags.extra_file_size;
                                is_shrink = tags.extra_is_shrink;
                                equiv_id = tags.extra_equiv_id;
                                in->lazy_loaded = 1;
                        }
                        in->dirty = 0;

                        if (!parent)
                                alloc_failed = 1;

                        /* directory stuff...
                         * hook up to parent
                         */

                        if (parent &&
                            parent->variant_type == YAFFS_OBJECT_TYPE_UNKNOWN) {
                                /* Set up as a directory */
                                parent->variant_type =
                                        YAFFS_OBJECT_TYPE_DIRECTORY;
                                INIT_LIST_HEAD(&parent->
                                                variant.dir_variant.children);
                        } else if (!parent ||
                                   parent->variant_type !=
                                        YAFFS_OBJECT_TYPE_DIRECTORY) {
                                /* Hoosterman, another problem....
                                 * Trying to use a non-directory as a directory
                                 */

                                yaffs_trace(YAFFS_TRACE_ERROR,
                                        "yaffs tragedy: attempting to use non-directory as a directory in scan. Put in lost+found."
                                        );
                                parent = dev->lost_n_found;
                        }
                        yaffs_add_obj_to_dir(parent, in);

                        is_unlinked = (parent == dev->del_dir) ||
                                        (parent == dev->unlinked_dir);

                        if (is_shrink)
                                /* Mark the block */
                                bi->has_shrink_hdr = 1;

                        /* Note re hardlinks.
                         * Since we might scan a hardlink before its equivalent
                         * object is scanned we put them all in a list.
                         * After scanning is complete, we should have all the
                         * objects, so we run through this list and fix up all
                         * the chains.
                         */

                        switch (in->variant_type) {
                        case YAFFS_OBJECT_TYPE_UNKNOWN:
                                /* Todo got a problem */
                                break;
                        case YAFFS_OBJECT_TYPE_FILE:
                                file_var = &in->variant.file_variant;
                                if (file_var->scanned_size < file_size) {
                                        /* This covers the case where the file
                                         * size is greater than the data held.
                                         * This will happen if the file is
                                         * resized to be larger than its
                                         * current data extents.
                                         */
                                        file_var->file_size = file_size;
                                        file_var->scanned_size = file_size;
                                }

                                if (file_var->shrink_size > file_size)
                                        file_var->shrink_size = file_size;

                                break;
                        case YAFFS_OBJECT_TYPE_HARDLINK:
                                hl_var = &in->variant.hardlink_variant;
                                if (!is_unlinked) {
                                        hl_var->equiv_id = equiv_id;
                                        list_add(&in->hard_links, hard_list);
                                }
                                break;
                        case YAFFS_OBJECT_TYPE_DIRECTORY:
                                /* Do nothing */
                                break;
                        case YAFFS_OBJECT_TYPE_SPECIAL:
                                /* Do nothing */
                                break;
                        case YAFFS_OBJECT_TYPE_SYMLINK:
                                sl_var = &in->variant.symlink_variant;
                                if (oh) {
                                        sl_var->alias =
                                            yaffs_clone_str(oh->alias);
                                        if (!sl_var->alias)
                                                alloc_failed = 1;
                                }
                                break;
                        }
                }
        }
        return alloc_failed ? YAFFS_FAIL : YAFFS_OK;
}

int yaffs2_scan_backwards(struct yaffs_dev *dev)
{
        int blk;
        int block_iter;
        int start_iter;
        int end_iter;
        int n_to_scan = 0;
        enum yaffs_block_state state;
        int c;
        LIST_HEAD(hard_list);
        struct yaffs_block_info *bi;
        u32 seq_number;
        int n_blocks = dev->internal_end_block - dev->internal_start_block + 1;
        u8 *chunk_data;
        int found_chunks;
        int alloc_failed = 0;
        struct yaffs_block_index *block_index = NULL;
        int alt_block_index = 0;
        int summary_available;

        yaffs_trace(YAFFS_TRACE_SCAN,
                "yaffs2_scan_backwards starts  intstartblk %d intendblk %d...",
                dev->internal_start_block, dev->internal_end_block);

        dev->seq_number = YAFFS_LOWEST_SEQUENCE_NUMBER;

        block_index =
                kmalloc(n_blocks * sizeof(struct yaffs_block_index), GFP_NOFS);

        if (!block_index) {
                block_index =
                    vmalloc(n_blocks * sizeof(struct yaffs_block_index));
                alt_block_index = 1;
        }

        if (!block_index) {
                yaffs_trace(YAFFS_TRACE_SCAN,
                        "yaffs2_scan_backwards() could not allocate block index!"
                        );
                return YAFFS_FAIL;
        }

        dev->blocks_in_checkpt = 0;

        chunk_data = yaffs_get_temp_buffer(dev);

        /* Scan all the blocks to determine their state */
        bi = dev->block_info;
        for (blk = dev->internal_start_block; blk <= dev->internal_end_block;
             blk++) {
                yaffs_clear_chunk_bits(dev, blk);
                bi->pages_in_use = 0;
                bi->soft_del_pages = 0;

                yaffs_query_init_block_state(dev, blk, &state, &seq_number);

                bi->block_state = state;
                bi->seq_number = seq_number;

                if (bi->seq_number == YAFFS_SEQUENCE_CHECKPOINT_DATA)
                        bi->block_state = YAFFS_BLOCK_STATE_CHECKPOINT;
                if (bi->seq_number == YAFFS_SEQUENCE_BAD_BLOCK)
                        bi->block_state = YAFFS_BLOCK_STATE_DEAD;

                yaffs_trace(YAFFS_TRACE_SCAN_DEBUG,
                        "Block scanning block %d state %d seq %d",
                        blk, bi->block_state, seq_number);

                if (bi->block_state == YAFFS_BLOCK_STATE_CHECKPOINT) {
                        dev->blocks_in_checkpt++;

                } else if (bi->block_state == YAFFS_BLOCK_STATE_DEAD) {
                        yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
                                "block %d is bad", blk);
                } else if (bi->block_state == YAFFS_BLOCK_STATE_EMPTY) {
                        yaffs_trace(YAFFS_TRACE_SCAN_DEBUG, "Block empty ");
                        dev->n_erased_blocks++;
                        dev->n_free_chunks += dev->param.chunks_per_block;
                } else if (bi->block_state ==
                                YAFFS_BLOCK_STATE_NEEDS_SCAN) {
                        /* Determine the highest sequence number */
                        if (seq_number >= YAFFS_LOWEST_SEQUENCE_NUMBER &&
                            seq_number < YAFFS_HIGHEST_SEQUENCE_NUMBER) {
                                block_index[n_to_scan].seq = seq_number;
                                block_index[n_to_scan].block = blk;
                                n_to_scan++;
                                if (seq_number >= dev->seq_number)
                                        dev->seq_number = seq_number;
                        } else {
                                /* TODO: Nasty sequence number! */
                                yaffs_trace(YAFFS_TRACE_SCAN,
                                        "Block scanning block %d has bad sequence number %d",
                                        blk, seq_number);
                        }
                }
                bi++;
        }

        yaffs_trace(YAFFS_TRACE_SCAN, "%d blocks to be sorted...", n_to_scan);

        cond_resched();

        /* Sort the blocks by sequence number */
        sort(block_index, n_to_scan, sizeof(struct yaffs_block_index),
                   yaffs2_ybicmp, NULL);

        cond_resched();

        yaffs_trace(YAFFS_TRACE_SCAN, "...done");

        /* Now scan the blocks looking at the data. */
        start_iter = 0;
        end_iter = n_to_scan - 1;
        yaffs_trace(YAFFS_TRACE_SCAN_DEBUG, "%d blocks to scan", n_to_scan);

        /* For each block.... backwards */
        for (block_iter = end_iter;
             !alloc_failed && block_iter >= start_iter;
             block_iter--) {
                /* Cooperative multitasking! This loop can run for so
                   long that watchdog timers expire. */
                cond_resched();

                /* get the block to scan in the correct order */
                blk = block_index[block_iter].block;
                bi = yaffs_get_block_info(dev, blk);

                summary_available = yaffs_summary_read(dev, dev->sum_tags, blk);

                /* For each chunk in each block that needs scanning.... */
                found_chunks = 0;
                if (summary_available)
                        c = dev->chunks_per_summary - 1;
                else
                        c = dev->param.chunks_per_block - 1;

                for (/* c is already initialised */;
                     !alloc_failed && c >= 0 &&
                     (bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCAN ||
                      bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING);
                      c--) {
                        /* Scan backwards...
                         * Read the tags and decide what to do
                         */
                        if (yaffs2_scan_chunk(dev, bi, blk, c,
                                        &found_chunks, chunk_data,
                                        &hard_list, summary_available) ==
                                        YAFFS_FAIL)
                                alloc_failed = 1;
                }

                if (bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCAN) {
                        /* If we got this far while scanning, then the block
                         * is fully allocated. */
                        bi->block_state = YAFFS_BLOCK_STATE_FULL;
                }

                /* Now let's see if it was dirty */
                if (bi->pages_in_use == 0 &&
                    !bi->has_shrink_hdr &&
                    bi->block_state == YAFFS_BLOCK_STATE_FULL) {
                        yaffs_block_became_dirty(dev, blk);
                }
        }

        yaffs_skip_rest_of_block(dev);

        if (alt_block_index)
                vfree(block_index);
        else
                kfree(block_index);

        /* Ok, we've done all the scanning.
         * Fix up the hard link chains.
         * We have scanned all the objects, now it's time to add these
         * hardlinks.
         */
        yaffs_link_fixup(dev, &hard_list);

        yaffs_release_temp_buffer(dev, chunk_data);

        if (alloc_failed)
                return YAFFS_FAIL;

        yaffs_trace(YAFFS_TRACE_SCAN, "yaffs2_scan_backwards ends");

        return YAFFS_OK;
}