yaffsfs.c: Fix NULL dereference in yaffs_unmount2_reldev()

[yaffs2.git] / yaffs_guts.c

/*
 * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
 *
 * Copyright (C) 2002-2018 Aleph One Ltd.
 *
 * 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 "yportenv.h"
#include "yaffs_trace.h"

#include "yaffs_guts.h"
#include "yaffs_endian.h"
#include "yaffs_getblockinfo.h"
#include "yaffs_tagscompat.h"
#include "yaffs_tagsmarshall.h"
#include "yaffs_nand.h"
#include "yaffs_yaffs1.h"
#include "yaffs_yaffs2.h"
#include "yaffs_bitmap.h"
#include "yaffs_verify.h"
#include "yaffs_nand.h"
#include "yaffs_packedtags2.h"
#include "yaffs_nameval.h"
#include "yaffs_allocator.h"
#include "yaffs_attribs.h"
#include "yaffs_summary.h"

/* Note YAFFS_GC_GOOD_ENOUGH must be <= YAFFS_GC_PASSIVE_THRESHOLD */
#define YAFFS_GC_GOOD_ENOUGH 2
#define YAFFS_GC_PASSIVE_THRESHOLD 4

#include "yaffs_ecc.h"

/* Forward declarations */

static int yaffs_wr_data_obj(struct yaffs_obj *in, int inode_chunk,
                             const u8 *buffer, int n_bytes, int use_reserve);

static void yaffs_fix_null_name(struct yaffs_obj *obj, YCHAR *name,
                                int buffer_size);

/* Function to calculate chunk and offset */

void yaffs_addr_to_chunk(struct yaffs_dev *dev, loff_t addr,
                                int *chunk_out, u32 *offset_out)
{
        int chunk;
        u32 offset;

        chunk = (u32) (addr >> dev->chunk_shift);

        if (dev->chunk_div == 1) {
                /* easy power of 2 case */
                offset = (u32) (addr & dev->chunk_mask);
        } else {
                /* Non power-of-2 case */

                loff_t chunk_base;

                chunk /= dev->chunk_div;

                chunk_base = ((loff_t) chunk) * dev->data_bytes_per_chunk;
                offset = (u32) (addr - chunk_base);
        }

        *chunk_out = chunk;
        *offset_out = offset;
}

/* Function to return the number of shifts for a power of 2 greater than or
 * equal to the given number
 * Note we don't try to cater for all possible numbers and this does not have to
 * be hellishly efficient.
 */

static inline u32 calc_shifts_ceiling(u32 x)
{
        int extra_bits;
        int shifts;

        shifts = extra_bits = 0;

        while (x > 1) {
                if (x & 1)
                        extra_bits++;
                x >>= 1;
                shifts++;
        }

        if (extra_bits)
                shifts++;

        return shifts;
}

/* Function to return the number of shifts to get a 1 in bit 0
 */

static inline u32 calc_shifts(u32 x)
{
        u32 shifts;

        shifts = 0;

        if (!x)
                return 0;

        while (!(x & 1)) {
                x >>= 1;
                shifts++;
        }

        return shifts;
}

/*
 * Temporary buffer manipulations.
 */

static int yaffs_init_tmp_buffers(struct yaffs_dev *dev)
{
        int i;
        u8 *buf = (u8 *) 1;

        memset(dev->temp_buffer, 0, sizeof(dev->temp_buffer));

        for (i = 0; buf && i < YAFFS_N_TEMP_BUFFERS; i++) {
                dev->temp_buffer[i].in_use = 0;
                buf = kmalloc(dev->param.total_bytes_per_chunk, GFP_NOFS);
                dev->temp_buffer[i].buffer = buf;
        }

        return buf ? YAFFS_OK : YAFFS_FAIL;
}

u8 *yaffs_get_temp_buffer(struct yaffs_dev * dev)
{
        int i;

        dev->temp_in_use++;
        if (dev->temp_in_use > dev->max_temp)
                dev->max_temp = dev->temp_in_use;

        for (i = 0; i < YAFFS_N_TEMP_BUFFERS; i++) {
                if (dev->temp_buffer[i].in_use == 0) {
                        dev->temp_buffer[i].in_use = 1;
                        return dev->temp_buffer[i].buffer;
                }
        }

        yaffs_trace(YAFFS_TRACE_BUFFERS, "Out of temp buffers");
        /*
         * If we got here then we have to allocate an unmanaged one
         * This is not good.
         */

        dev->unmanaged_buffer_allocs++;
        return kmalloc(dev->data_bytes_per_chunk, GFP_NOFS);

}

void yaffs_release_temp_buffer(struct yaffs_dev *dev, u8 *buffer)
{
        int i;

        dev->temp_in_use--;

        for (i = 0; i < YAFFS_N_TEMP_BUFFERS; i++) {
                if (dev->temp_buffer[i].buffer == buffer) {
                        dev->temp_buffer[i].in_use = 0;
                        return;
                }
        }

        if (buffer) {
                /* assume it is an unmanaged one. */
                yaffs_trace(YAFFS_TRACE_BUFFERS,
                        "Releasing unmanaged temp buffer");
                kfree(buffer);
                dev->unmanaged_buffer_deallocs++;
        }

}

/*
 * Functions for robustisizing TODO
 *
 */

static void yaffs_handle_chunk_wr_ok(struct yaffs_dev *dev, int nand_chunk,
                                     const u8 *data,
                                     const struct yaffs_ext_tags *tags)
{
        (void) dev;
        (void) nand_chunk;
        (void) data;
        (void) tags;
}

static void yaffs_handle_chunk_update(struct yaffs_dev *dev, int nand_chunk,
                                      const struct yaffs_ext_tags *tags)
{
        (void) dev;
        (void) nand_chunk;
        (void) tags;
}

void yaffs_handle_chunk_error(struct yaffs_dev *dev,
                              struct yaffs_block_info *bi)
{
        if (!bi->gc_prioritise) {
                bi->gc_prioritise = 1;
                dev->has_pending_prioritised_gc = 1;
                bi->chunk_error_strikes++;

                if (bi->chunk_error_strikes > 3) {
                        bi->needs_retiring = 1; /* Too many stikes, so retire */
                        yaffs_trace(YAFFS_TRACE_ALWAYS,
                                "yaffs: Block struck out");

                }
        }
}

static void yaffs_handle_chunk_wr_error(struct yaffs_dev *dev, int nand_chunk,
                                        int erased_ok)
{
        int flash_block = nand_chunk / dev->param.chunks_per_block;
        struct yaffs_block_info *bi = yaffs_get_block_info(dev, flash_block);

        yaffs_handle_chunk_error(dev, bi);

        if (erased_ok) {
                /* Was an actual write failure,
                 * so mark the block for retirement.*/
                bi->needs_retiring = 1;
                yaffs_trace(YAFFS_TRACE_ERROR | YAFFS_TRACE_BAD_BLOCKS,
                  "**>> Block %d needs retiring", flash_block);
        }

        /* Delete the chunk */
        yaffs_chunk_del(dev, nand_chunk, 1, __LINE__);
        yaffs_skip_rest_of_block(dev);
}

/*
 * Verification code
 */

/*
 *  Simple hash function. Needs to have a reasonable spread
 */

static inline int yaffs_hash_fn(int n)
{
        if (n < 0)
                n = -n;
        return n % YAFFS_NOBJECT_BUCKETS;
}

/*
 * Access functions to useful fake objects.
 * Note that root might have a presence in NAND if permissions are set.
 */

struct yaffs_obj *yaffs_root(struct yaffs_dev *dev)
{
        return dev->root_dir;
}

struct yaffs_obj *yaffs_lost_n_found(struct yaffs_dev *dev)
{
        return dev->lost_n_found;
}

/*
 *  Erased NAND checking functions
 */

int yaffs_check_ff(u8 *buffer, int n_bytes)
{
        /* Horrible, slow implementation */
        while (n_bytes--) {
                if (*buffer != 0xff)
                        return 0;
                buffer++;
        }
        return 1;
}

static int yaffs_check_chunk_erased(struct yaffs_dev *dev, int nand_chunk)
{
        int retval = YAFFS_OK;
        u8 *data = yaffs_get_temp_buffer(dev);
        struct yaffs_ext_tags tags;
        int result;

        result = yaffs_rd_chunk_tags_nand(dev, nand_chunk, data, &tags);

        if (result == YAFFS_FAIL ||
            tags.ecc_result > YAFFS_ECC_RESULT_NO_ERROR)
                retval = YAFFS_FAIL;

        if (!yaffs_check_ff(data, dev->data_bytes_per_chunk) ||
                tags.chunk_used) {
                yaffs_trace(YAFFS_TRACE_NANDACCESS,
                        "Chunk %d not erased", nand_chunk);
                retval = YAFFS_FAIL;
        }

        yaffs_release_temp_buffer(dev, data);

        return retval;

}

static int yaffs_verify_chunk_written(struct yaffs_dev *dev,
                                      int nand_chunk,
                                      const u8 *data,
                                      struct yaffs_ext_tags *tags)
{
        int retval = YAFFS_OK;
        struct yaffs_ext_tags temp_tags;
        u8 *buffer = yaffs_get_temp_buffer(dev);
        int result;

        result = yaffs_rd_chunk_tags_nand(dev, nand_chunk, buffer, &temp_tags);
        if (result == YAFFS_FAIL ||
            memcmp(buffer, data, dev->data_bytes_per_chunk) ||
            temp_tags.obj_id != tags->obj_id ||
            temp_tags.chunk_id != tags->chunk_id ||
            temp_tags.n_bytes != tags->n_bytes)
                retval = YAFFS_FAIL;

        yaffs_release_temp_buffer(dev, buffer);

        return retval;
}


int yaffs_check_alloc_available(struct yaffs_dev *dev, int n_chunks)
{
        int reserved_chunks;
        int reserved_blocks = dev->param.n_reserved_blocks;
        int checkpt_blocks;

        checkpt_blocks = yaffs_calc_checkpt_blocks_required(dev);

        reserved_chunks =
            (reserved_blocks + checkpt_blocks) * dev->param.chunks_per_block;

        return (dev->n_free_chunks > (reserved_chunks + n_chunks));
}

static int yaffs_find_alloc_block(struct yaffs_dev *dev)
{
        u32 i;
        struct yaffs_block_info *bi;

        if (dev->n_erased_blocks < 1) {
                /* Hoosterman we've got a problem.
                 * Can't get space to gc
                 */
                yaffs_trace(YAFFS_TRACE_ERROR,
                  "yaffs tragedy: no more erased blocks");

                return -1;
        }

        /* Find an empty block. */

        for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
                dev->alloc_block_finder++;
                if (dev->alloc_block_finder < (int)dev->internal_start_block
                    || dev->alloc_block_finder > (int)dev->internal_end_block) {
                        dev->alloc_block_finder = dev->internal_start_block;
                }

                bi = yaffs_get_block_info(dev, dev->alloc_block_finder);

                if (bi->block_state == YAFFS_BLOCK_STATE_EMPTY) {
                        bi->block_state = YAFFS_BLOCK_STATE_ALLOCATING;
                        dev->seq_number++;
                        bi->seq_number = dev->seq_number;
                        dev->n_erased_blocks--;
                        yaffs_trace(YAFFS_TRACE_ALLOCATE,
                          "Allocated block %d, seq  %d, %d left" ,
                           dev->alloc_block_finder, dev->seq_number,
                           dev->n_erased_blocks);
                        return dev->alloc_block_finder;
                }
        }

        yaffs_trace(YAFFS_TRACE_ALWAYS,
                "yaffs tragedy: no more erased blocks, but there should have been %d",
                dev->n_erased_blocks);

        return -1;
}

static int yaffs_alloc_chunk(struct yaffs_dev *dev, int use_reserver,
                             struct yaffs_block_info **block_ptr)
{
        int ret_val;
        struct yaffs_block_info *bi;

        if (dev->alloc_block < 0) {
                /* Get next block to allocate off */
                dev->alloc_block = yaffs_find_alloc_block(dev);
                dev->alloc_page = 0;
        }

        if (!use_reserver && !yaffs_check_alloc_available(dev, 1)) {
                /* No space unless we're allowed to use the reserve. */
                return -1;
        }

        if (dev->n_erased_blocks < (int)dev->param.n_reserved_blocks
            && dev->alloc_page == 0)
                yaffs_trace(YAFFS_TRACE_ALLOCATE, "Allocating reserve");

        /* Next page please.... */
        if (dev->alloc_block >= 0) {
                bi = yaffs_get_block_info(dev, dev->alloc_block);

                ret_val = (dev->alloc_block * dev->param.chunks_per_block) +
                    dev->alloc_page;
                bi->pages_in_use++;
                yaffs_set_chunk_bit(dev, dev->alloc_block, dev->alloc_page);

                dev->alloc_page++;

                dev->n_free_chunks--;

                /* If the block is full set the state to full */
                if (dev->alloc_page >= dev->param.chunks_per_block) {
                        bi->block_state = YAFFS_BLOCK_STATE_FULL;
                        dev->alloc_block = -1;
                }

                if (block_ptr)
                        *block_ptr = bi;

                return ret_val;
        }

        yaffs_trace(YAFFS_TRACE_ERROR,
                "!!!!!!!!! Allocator out !!!!!!!!!!!!!!!!!");

        return -1;
}

static int yaffs_get_erased_chunks(struct yaffs_dev *dev)
{
        int n;

        n = dev->n_erased_blocks * dev->param.chunks_per_block;

        if (dev->alloc_block > 0)
                n += (dev->param.chunks_per_block - dev->alloc_page);

        return n;

}

/*
 * yaffs_skip_rest_of_block() skips over the rest of the allocation block
 * if we don't want to write to it.
 */
void yaffs_skip_rest_of_block(struct yaffs_dev *dev)
{
        struct yaffs_block_info *bi;

        if (dev->alloc_block > 0) {
                bi = yaffs_get_block_info(dev, dev->alloc_block);
                if (bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING) {
                        bi->block_state = YAFFS_BLOCK_STATE_FULL;
                        dev->alloc_block = -1;
                }
        }
}

static int yaffs_write_new_chunk(struct yaffs_dev *dev,
                                 const u8 *data,
                                 struct yaffs_ext_tags *tags, int use_reserver)
{
        u32 attempts = 0;
        int write_ok = 0;
        int chunk;

        yaffs2_checkpt_invalidate(dev);

        do {
                struct yaffs_block_info *bi = 0;
                int erased_ok = 0;

                chunk = yaffs_alloc_chunk(dev, use_reserver, &bi);
                if (chunk < 0) {
                        /* no space */
                        break;
                }

                /* First check this chunk is erased, if it needs
                 * checking.  The checking policy (unless forced
                 * always on) is as follows:
                 *
                 * Check the first page we try to write in a block.
                 * If the check passes then we don't need to check any
                 * more.        If the check fails, we check again...
                 * If the block has been erased, we don't need to check.
                 *
                 * However, if the block has been prioritised for gc,
                 * then we think there might be something odd about
                 * this block and stop using it.
                 *
                 * Rationale: We should only ever see chunks that have
                 * not been erased if there was a partially written
                 * chunk due to power loss.  This checking policy should
                 * catch that case with very few checks and thus save a
                 * lot of checks that are most likely not needed.
                 *
                 * Mods to the above
                 * If an erase check fails or the write fails we skip the
                 * rest of the block.
                 */

                /* let's give it a try */
                attempts++;

                if (dev->param.always_check_erased)
                        bi->skip_erased_check = 0;

                if (!bi->skip_erased_check) {
                        erased_ok = yaffs_check_chunk_erased(dev, chunk);
                        if (erased_ok != YAFFS_OK) {
                                yaffs_trace(YAFFS_TRACE_ERROR,
                                  "**>> yaffs chunk %d was not erased",
                                  chunk);

                                /* If not erased, delete this one,
                                 * skip rest of block and
                                 * try another chunk */
                                yaffs_chunk_del(dev, chunk, 1, __LINE__);
                                yaffs_skip_rest_of_block(dev);
                                continue;
                        }
                }

                write_ok = yaffs_wr_chunk_tags_nand(dev, chunk, data, tags);

                if (!bi->skip_erased_check)
                        write_ok =
                            yaffs_verify_chunk_written(dev, chunk, data, tags);

                if (write_ok != YAFFS_OK) {
                        /* Clean up aborted write, skip to next block and
                         * try another chunk */
                        yaffs_handle_chunk_wr_error(dev, chunk, erased_ok);
                        continue;
                }

                bi->skip_erased_check = 1;

                /* Copy the data into the robustification buffer */
                yaffs_handle_chunk_wr_ok(dev, chunk, data, tags);

        } while (write_ok != YAFFS_OK &&
                 (yaffs_wr_attempts == 0 || attempts <= yaffs_wr_attempts));

        if (!write_ok)
                chunk = -1;

        if (attempts > 1) {
                yaffs_trace(YAFFS_TRACE_ERROR,
                        "**>> yaffs write required %d attempts",
                        attempts);
                dev->n_retried_writes += (attempts - 1);
        }

        return chunk;
}

/*
 * Block retiring for handling a broken block.
 */

static void yaffs_retire_block(struct yaffs_dev *dev, int flash_block)
{
        struct yaffs_block_info *bi = yaffs_get_block_info(dev, flash_block);

        yaffs2_checkpt_invalidate(dev);

        yaffs2_clear_oldest_dirty_seq(dev, bi);

        if (yaffs_mark_bad(dev, flash_block) != YAFFS_OK) {
                if (yaffs_erase_block(dev, flash_block) != YAFFS_OK) {
                        yaffs_trace(YAFFS_TRACE_ALWAYS,
                                "yaffs: Failed to mark bad and erase block %d",
                                flash_block);
                } else {
                        struct yaffs_ext_tags tags;
                        int chunk_id =
                            flash_block * dev->param.chunks_per_block;

                        u8 *buffer = yaffs_get_temp_buffer(dev);

                        memset(buffer, 0xff, dev->data_bytes_per_chunk);
                        memset(&tags, 0, sizeof(tags));
                        tags.seq_number = YAFFS_SEQUENCE_BAD_BLOCK;
                        if (dev->tagger.write_chunk_tags_fn(dev, chunk_id -
                                                        dev->chunk_offset,
                                                        buffer,
                                                        &tags) != YAFFS_OK)
                                yaffs_trace(YAFFS_TRACE_ALWAYS,
                                        "yaffs: Failed to write bad block marker to block %d",
                                        flash_block);

                        yaffs_release_temp_buffer(dev, buffer);
                }
        }

        bi->block_state = YAFFS_BLOCK_STATE_DEAD;
        bi->gc_prioritise = 0;
        bi->needs_retiring = 0;

        dev->n_retired_blocks++;
}

/*---------------- Name handling functions ------------*/

static void yaffs_load_name_from_oh(struct yaffs_dev *dev, YCHAR *name,
                                    const YCHAR *oh_name, int buff_size)
{
#ifdef CONFIG_YAFFS_AUTO_UNICODE
        if (dev->param.auto_unicode) {
                if (*oh_name) {
                        /* It is an ASCII name, do an ASCII to
                         * unicode conversion */
                        const char *ascii_oh_name = (const char *)oh_name;
                        int n = buff_size - 1;
                        while (n > 0 && *ascii_oh_name) {
                                *name = *ascii_oh_name;
                                name++;
                                ascii_oh_name++;
                                n--;
                        }
                } else {
                        strncpy(name, oh_name + 1, buff_size - 1);
                }
        } else {
#else
        (void) dev;
        {
#endif
                strncpy(name, oh_name, buff_size - 1);
        }
}

static void yaffs_load_oh_from_name(struct yaffs_dev *dev, YCHAR *oh_name,
                                    const YCHAR *name)
{
#ifdef CONFIG_YAFFS_AUTO_UNICODE

        int is_ascii;
        const YCHAR *w;

        if (dev->param.auto_unicode) {

                is_ascii = 1;
                w = name;

                /* Figure out if the name will fit in ascii character set */
                while (is_ascii && *w) {
                        if ((*w) & 0xff00)
                                is_ascii = 0;
                        w++;
                }

                if (is_ascii) {
                        /* It is an ASCII name, so convert unicode to ascii */
                        char *ascii_oh_name = (char *)oh_name;
                        int n = YAFFS_MAX_NAME_LENGTH - 1;
                        while (n > 0 && *name) {
                                *ascii_oh_name = *name;
                                name++;
                                ascii_oh_name++;
                                n--;
                        }
                } else {
                        /* Unicode name, so save starting at the second YCHAR */
                        *oh_name = 0;
                        strncpy(oh_name + 1, name, YAFFS_MAX_NAME_LENGTH - 2);
                }
        } else {
#else
        dev = dev;
        {
#endif
                strncpy(oh_name, name, YAFFS_MAX_NAME_LENGTH - 1);
        }
}

static u16 yaffs_calc_name_sum(const YCHAR *name)
{
        u16 sum = 0;
        u16 i = 1;

        if (!name)
                return 0;

        while ((*name) && i < (YAFFS_MAX_NAME_LENGTH / 2)) {

                /* 0x1f mask is case insensitive */
                sum += ((*name) & 0x1f) * i;
                i++;
                name++;
        }
        return sum;
}


void yaffs_set_obj_name(struct yaffs_obj *obj, const YCHAR * name)
{
        memset(obj->short_name, 0, sizeof(obj->short_name));

        if (name && !name[0]) {
                yaffs_fix_null_name(obj, obj->short_name,
                                YAFFS_SHORT_NAME_LENGTH);
                name = obj->short_name;
        } else if (name &&
                strnlen(name, YAFFS_SHORT_NAME_LENGTH + 1) <=
                YAFFS_SHORT_NAME_LENGTH)  {
                strcpy(obj->short_name, name);
        }

        obj->sum = yaffs_calc_name_sum(name);
}

void yaffs_set_obj_name_from_oh(struct yaffs_obj *obj,
                                const struct yaffs_obj_hdr *oh)
{
#ifdef CONFIG_YAFFS_AUTO_UNICODE
        YCHAR tmp_name[YAFFS_MAX_NAME_LENGTH + 1];
        memset(tmp_name, 0, sizeof(tmp_name));
        yaffs_load_name_from_oh(obj->my_dev, tmp_name, oh->name,
                                YAFFS_MAX_NAME_LENGTH + 1);
        yaffs_set_obj_name(obj, tmp_name);
#else
        yaffs_set_obj_name(obj, oh->name);
#endif
}

loff_t yaffs_max_file_size(struct yaffs_dev *dev)
{
        if (sizeof(loff_t) < 8)
                return YAFFS_MAX_FILE_SIZE_32;
        else
                return ((loff_t) YAFFS_MAX_CHUNK_ID) * dev->data_bytes_per_chunk;
}

/*-------------------- TNODES -------------------

 * List of spare tnodes
 * The list is hooked together using the first pointer
 * in the tnode.
 */

struct yaffs_tnode *yaffs_get_tnode(struct yaffs_dev *dev)
{
        struct yaffs_tnode *tn = yaffs_alloc_raw_tnode(dev);

        if (tn) {
                memset(tn, 0, dev->tnode_size);
                dev->n_tnodes++;
        }

        dev->checkpoint_blocks_required = 0;    /* force recalculation */

        return tn;
}

/* FreeTnode frees up a tnode and puts it back on the free list */
static void yaffs_free_tnode(struct yaffs_dev *dev, struct yaffs_tnode *tn)
{
        yaffs_free_raw_tnode(dev, tn);
        dev->n_tnodes--;
        dev->checkpoint_blocks_required = 0;    /* force recalculation */
}

static void yaffs_deinit_tnodes_and_objs(struct yaffs_dev *dev)
{
        yaffs_deinit_raw_tnodes_and_objs(dev);
        dev->n_obj = 0;
        dev->n_tnodes = 0;
}

static void yaffs_load_tnode_0(struct yaffs_dev *dev, struct yaffs_tnode *tn,
                        unsigned pos, unsigned val)
{
        u32 *map = (u32 *) tn;
        u32 bit_in_map;
        u32 bit_in_word;
        u32 word_in_map;
        u32 mask;

        pos &= YAFFS_TNODES_LEVEL0_MASK;
        val >>= dev->chunk_grp_bits;

        bit_in_map = pos * dev->tnode_width;
        word_in_map = bit_in_map / 32;
        bit_in_word = bit_in_map & (32 - 1);

        mask = dev->tnode_mask << bit_in_word;

        map[word_in_map] &= ~mask;
        map[word_in_map] |= (mask & (val << bit_in_word));

        if (dev->tnode_width > (32 - bit_in_word)) {
                bit_in_word = (32 - bit_in_word);
                word_in_map++;
                mask =
                    dev->tnode_mask >> bit_in_word;
                map[word_in_map] &= ~mask;
                map[word_in_map] |= (mask & (val >> bit_in_word));
        }
}

u32 yaffs_get_group_base(struct yaffs_dev *dev, struct yaffs_tnode *tn,
                         unsigned pos)
{
        u32 *map = (u32 *) tn;
        u32 bit_in_map;
        u32 bit_in_word;
        u32 word_in_map;
        u32 val;

        pos &= YAFFS_TNODES_LEVEL0_MASK;

        bit_in_map = pos * dev->tnode_width;
        word_in_map = bit_in_map / 32;
        bit_in_word = bit_in_map & (32 - 1);

        val = map[word_in_map] >> bit_in_word;

        if (dev->tnode_width > (32 - bit_in_word)) {
                bit_in_word = (32 - bit_in_word);
                word_in_map++;
                val |= (map[word_in_map] << bit_in_word);
        }

        val &= dev->tnode_mask;
        val <<= dev->chunk_grp_bits;

        return val;
}

/* ------------------- End of individual tnode manipulation -----------------*/

/* ---------Functions to manipulate the look-up tree (made up of tnodes) ------
 * The look up tree is represented by the top tnode and the number of top_level
 * in the tree. 0 means only the level 0 tnode is in the tree.
 */

/* FindLevel0Tnode finds the level 0 tnode, if one exists. */
struct yaffs_tnode *yaffs_find_tnode_0(struct yaffs_dev *dev,
                                       struct yaffs_file_var *file_struct,
                                       u32 chunk_id)
{
        struct yaffs_tnode *tn = file_struct->top;
        u32 i;
        int required_depth;
        int level = file_struct->top_level;

        (void) dev;

        /* Check sane level and chunk Id */
        if (level < 0 || level > YAFFS_TNODES_MAX_LEVEL)
                return NULL;

        if (chunk_id > YAFFS_MAX_CHUNK_ID)
                return NULL;

        /* First check we're tall enough (ie enough top_level) */

        i = chunk_id >> YAFFS_TNODES_LEVEL0_BITS;
        required_depth = 0;
        while (i) {
                i >>= YAFFS_TNODES_INTERNAL_BITS;
                required_depth++;
        }

        if (required_depth > file_struct->top_level)
                return NULL;    /* Not tall enough, so we can't find it */

        /* Traverse down to level 0 */
        while (level > 0 && tn) {
                tn = tn->internal[(chunk_id >>
                                   (YAFFS_TNODES_LEVEL0_BITS +
                                    (level - 1) *
                                    YAFFS_TNODES_INTERNAL_BITS)) &
                                  YAFFS_TNODES_INTERNAL_MASK];
                level--;
        }

        return tn;
}

/* add_find_tnode_0 finds the level 0 tnode if it exists,
 * otherwise first expands the tree.
 * This happens in two steps:
 *  1. If the tree isn't tall enough, then make it taller.
 *  2. Scan down the tree towards the level 0 tnode adding tnodes if required.
 *
 * Used when modifying the tree.
 *
 *  If the tn argument is NULL, then a fresh tnode will be added otherwise the
 *  specified tn will be plugged into the ttree.
 */

struct yaffs_tnode *yaffs_add_find_tnode_0(struct yaffs_dev *dev,
                                           struct yaffs_file_var *file_struct,
                                           u32 chunk_id,
                                           struct yaffs_tnode *passed_tn)
{
        int required_depth;
        int i;
        int l;
        struct yaffs_tnode *tn;
        u32 x;

        /* Check sane level and page Id */
        if (file_struct->top_level < 0 ||
            file_struct->top_level > YAFFS_TNODES_MAX_LEVEL)
                return NULL;

        if (chunk_id > YAFFS_MAX_CHUNK_ID)
                return NULL;

        /* First check we're tall enough (ie enough top_level) */

        x = chunk_id >> YAFFS_TNODES_LEVEL0_BITS;
        required_depth = 0;
        while (x) {
                x >>= YAFFS_TNODES_INTERNAL_BITS;
                required_depth++;
        }

        if (required_depth > file_struct->top_level) {
                /* Not tall enough, gotta make the tree taller */
                for (i = file_struct->top_level; i < required_depth; i++) {

                        tn = yaffs_get_tnode(dev);

                        if (tn) {
                                tn->internal[0] = file_struct->top;
                                file_struct->top = tn;
                                file_struct->top_level++;
                        } else {
                                yaffs_trace(YAFFS_TRACE_ERROR,
                                        "yaffs: no more tnodes");
                                return NULL;
                        }
                }
        }

        /* Traverse down to level 0, adding anything we need */

        l = file_struct->top_level;
        tn = file_struct->top;

        if (l > 0) {
                while (l > 0 && tn) {
                        x = (chunk_id >>
                             (YAFFS_TNODES_LEVEL0_BITS +
                              (l - 1) * YAFFS_TNODES_INTERNAL_BITS)) &
                            YAFFS_TNODES_INTERNAL_MASK;

                        if ((l > 1) && !tn->internal[x]) {
                                /* Add missing non-level-zero tnode */
                                tn->internal[x] = yaffs_get_tnode(dev);
                                if (!tn->internal[x])
                                        return NULL;
                        } else if (l == 1) {
                                /* Looking from level 1 at level 0 */
                                if (passed_tn) {
                                        /* If we already have one, release it */
                                        if (tn->internal[x])
                                                yaffs_free_tnode(dev,
                                                        tn->internal[x]);
                                        tn->internal[x] = passed_tn;

                                } else if (!tn->internal[x]) {
                                        /* Don't have one, none passed in */
                                        tn->internal[x] = yaffs_get_tnode(dev);
                                        if (!tn->internal[x])
                                                return NULL;
                                }
                        }

                        tn = tn->internal[x];
                        l--;
                }
        } else {
                /* top is level 0 */
                if (passed_tn) {
                        memcpy(tn, passed_tn,
                               (dev->tnode_width * YAFFS_NTNODES_LEVEL0) / 8);
                        yaffs_free_tnode(dev, passed_tn);
                }
        }

        return tn;
}

static int yaffs_tags_match(const struct yaffs_ext_tags *tags, int obj_id,
                            int chunk_obj)
{
        return (tags->chunk_id == (u32)chunk_obj &&
                tags->obj_id == (u32)obj_id &&
                !tags->is_deleted) ? 1 : 0;

}

static int yaffs_find_chunk_in_group(struct yaffs_dev *dev, int the_chunk,
                                        struct yaffs_ext_tags *tags, int obj_id,
                                        int inode_chunk)
{
        int j;

        for (j = 0; the_chunk && j < dev->chunk_grp_size; j++) {
                if (yaffs_check_chunk_bit
                    (dev, the_chunk / dev->param.chunks_per_block,
                     the_chunk % dev->param.chunks_per_block)) {

                        if (dev->chunk_grp_size == 1)
                                return the_chunk;
                        else {
                                yaffs_rd_chunk_tags_nand(dev, the_chunk, NULL,
                                                         tags);
                                if (yaffs_tags_match(tags,
                                                        obj_id, inode_chunk)) {
                                        /* found it; */
                                        return the_chunk;
                                }
                        }
                }
                the_chunk++;
        }
        return -1;
}

int yaffs_find_chunk_in_file(struct yaffs_obj *in, int inode_chunk,
                                    struct yaffs_ext_tags *tags)
{
        /*Get the Tnode, then get the level 0 offset chunk offset */
        struct yaffs_tnode *tn;
        int the_chunk = -1;
        struct yaffs_ext_tags local_tags;
        int ret_val = -1;
        struct yaffs_dev *dev = in->my_dev;

        if (!tags) {
                /* Passed a NULL, so use our own tags space */
                tags = &local_tags;
        }

        tn = yaffs_find_tnode_0(dev, &in->variant.file_variant, inode_chunk);

        if (!tn)
                return ret_val;

        the_chunk = yaffs_get_group_base(dev, tn, inode_chunk);

        ret_val = yaffs_find_chunk_in_group(dev, the_chunk, tags, in->obj_id,
                                              inode_chunk);
        return ret_val;
}

static int yaffs_find_del_file_chunk(struct yaffs_obj *in, int inode_chunk,
                                     struct yaffs_ext_tags *tags)
{
        /* Get the Tnode, then get the level 0 offset chunk offset */
        struct yaffs_tnode *tn;
        int the_chunk = -1;
        struct yaffs_ext_tags local_tags;
        struct yaffs_dev *dev = in->my_dev;
        int ret_val = -1;

        if (!tags) {
                /* Passed a NULL, so use our own tags space */
                tags = &local_tags;
        }

        tn = yaffs_find_tnode_0(dev, &in->variant.file_variant, inode_chunk);

        if (!tn)
                return ret_val;

        the_chunk = yaffs_get_group_base(dev, tn, inode_chunk);

        ret_val = yaffs_find_chunk_in_group(dev, the_chunk, tags, in->obj_id,
                                              inode_chunk);

        /* Delete the entry in the filestructure (if found) */
        if (ret_val != -1)
                yaffs_load_tnode_0(dev, tn, inode_chunk, 0);

        return ret_val;
}

int yaffs_put_chunk_in_file(struct yaffs_obj *in, int inode_chunk,
                            int nand_chunk, int in_scan)
{
        /* NB in_scan is zero unless scanning.
         * For forward scanning, in_scan is > 0;
         * for backward scanning in_scan is < 0
         *
         * nand_chunk = 0 is a dummy insert to make sure the tnodes are there.
         */

        struct yaffs_tnode *tn;
        struct yaffs_dev *dev = in->my_dev;
        int existing_cunk;
        struct yaffs_ext_tags existing_tags;
        struct yaffs_ext_tags new_tags;
        unsigned existing_serial, new_serial;

        if (in->variant_type != YAFFS_OBJECT_TYPE_FILE) {
                /* Just ignore an attempt at putting a chunk into a non-file
                 * during scanning.
                 * If it is not during Scanning then something went wrong!
                 */
                if (!in_scan) {
                        yaffs_trace(YAFFS_TRACE_ERROR,
                                "yaffs tragedy:attempt to put data chunk into a non-file"
                                );
                        BUG();
                }

                yaffs_chunk_del(dev, nand_chunk, 1, __LINE__);
                return YAFFS_OK;
        }

        tn = yaffs_add_find_tnode_0(dev,
                                    &in->variant.file_variant,
                                    inode_chunk, NULL);
        if (!tn)
                return YAFFS_FAIL;

        if (!nand_chunk)
                /* Dummy insert, bail now */
                return YAFFS_OK;

        existing_cunk = yaffs_get_group_base(dev, tn, inode_chunk);

        if (in_scan != 0) {
                /* If we're scanning then we need to test for duplicates
                 * NB This does not need to be efficient since it should only
                 * happen when the power fails during a write, then only one
                 * chunk should ever be affected.
                 *
                 * Correction for YAFFS2: This could happen quite a lot and we
                 * need to think about efficiency! TODO
                 * Update: For backward scanning we don't need to re-read tags
                 * so this is quite cheap.
                 */

                if (existing_cunk > 0) {
                        /* NB Right now existing chunk will not be real
                         * chunk_id if the chunk group size > 1
                         * thus we have to do a FindChunkInFile to get the
                         * real chunk id.
                         *
                         * We have a duplicate now we need to decide which
                         * one to use:
                         *
                         * Backwards scanning YAFFS2: The old one is what
                         * we use, dump the new one.
                         * YAFFS1: Get both sets of tags and compare serial
                         * numbers.
                         */

                        if (in_scan > 0) {
                                /* Only do this for forward scanning */
                                yaffs_rd_chunk_tags_nand(dev,
                                                         nand_chunk,
                                                         NULL, &new_tags);

                                /* Do a proper find */
                                existing_cunk =
                                    yaffs_find_chunk_in_file(in, inode_chunk,
                                                             &existing_tags);
                        }

                        if (existing_cunk <= 0) {
                                /*Hoosterman - how did this happen? */

                                yaffs_trace(YAFFS_TRACE_ERROR,
                                        "yaffs tragedy: existing chunk < 0 in scan"
                                        );

                        }

                        /* NB The deleted flags should be false, otherwise
                         * the chunks will not be loaded during a scan
                         */

                        if (in_scan > 0) {
                                new_serial = new_tags.serial_number;
                                existing_serial = existing_tags.serial_number;
                        }

                        if ((in_scan > 0) &&
                            (existing_cunk <= 0 ||
                             ((existing_serial + 1) & 3) == new_serial)) {
                                /* Forward scanning.
                                 * Use new
                                 * Delete the old one and drop through to
                                 * update the tnode
                                 */
                                yaffs_chunk_del(dev, existing_cunk, 1,
                                                __LINE__);
                        } else {
                                /* Backward scanning or we want to use the
                                 * existing one
                                 * Delete the new one and return early so that
                                 * the tnode isn't changed
                                 */
                                yaffs_chunk_del(dev, nand_chunk, 1, __LINE__);
                                return YAFFS_OK;
                        }
                }

        }

        if (existing_cunk == 0)
                in->n_data_chunks++;

        yaffs_load_tnode_0(dev, tn, inode_chunk, nand_chunk);

        return YAFFS_OK;
}

static void yaffs_soft_del_chunk(struct yaffs_dev *dev, int chunk)
{
        struct yaffs_block_info *the_block;
        unsigned block_no;

        yaffs_trace(YAFFS_TRACE_DELETION, "soft delete chunk %d", chunk);

        block_no = chunk / dev->param.chunks_per_block;
        the_block = yaffs_get_block_info(dev, block_no);
        if (the_block) {
                the_block->soft_del_pages++;
                dev->n_free_chunks++;
                yaffs2_update_oldest_dirty_seq(dev, block_no, the_block);
        }
}

/* SoftDeleteWorker scans backwards through the tnode tree and soft deletes all
 * the chunks in the file.
 * All soft deleting does is increment the block's softdelete count and pulls
 * the chunk out of the tnode.
 * Thus, essentially this is the same as DeleteWorker except that the chunks
 * are soft deleted.
 */

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

        if (!tn)
                return 1;

        if (level > 0) {
                for (i = YAFFS_NTNODES_INTERNAL - 1;
                        all_done && i >= 0;
                        i--) {
                        if (tn->internal[i]) {
                                all_done =
                                    yaffs_soft_del_worker(in,
                                        tn->internal[i],
                                        level - 1,
                                        (chunk_offset <<
                                        YAFFS_TNODES_INTERNAL_BITS)
                                        + i);
                                if (all_done) {
                                        yaffs_free_tnode(dev,
                                                tn->internal[i]);
                                        tn->internal[i] = NULL;
                                } else {
                                        /* Can this happen? */
                                }
                        }
                }
                return (all_done) ? 1 : 0;
        }

        /* level 0 */
         for (i = YAFFS_NTNODES_LEVEL0 - 1; i >= 0; i--) {
                the_chunk = yaffs_get_group_base(dev, tn, i);
                if (the_chunk) {
                        yaffs_soft_del_chunk(dev, the_chunk);
                        yaffs_load_tnode_0(dev, tn, i, 0);
                }
        }
        return 1;
}

static void yaffs_remove_obj_from_dir(struct yaffs_obj *obj)
{
        struct yaffs_dev *dev = obj->my_dev;
        struct yaffs_obj *parent;

        yaffs_verify_obj_in_dir(obj);
        parent = obj->parent;

        yaffs_verify_dir(parent);

        if (dev && dev->param.remove_obj_fn)
                dev->param.remove_obj_fn(obj);

        list_del_init(&obj->siblings);
        obj->parent = NULL;

        yaffs_verify_dir(parent);
}

void yaffs_add_obj_to_dir(struct yaffs_obj *directory, struct yaffs_obj *obj)
{
        if (!directory) {
                yaffs_trace(YAFFS_TRACE_ALWAYS,
                        "tragedy: Trying to add an object to a null pointer directory"
                        );
                BUG();
                return;
        }
        if (directory->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
                yaffs_trace(YAFFS_TRACE_ALWAYS,
                        "tragedy: Trying to add an object to a non-directory"
                        );
                BUG();
        }

        if (obj->siblings.prev == NULL) {
                /* Not initialised */
                BUG();
        }

        yaffs_verify_dir(directory);

        yaffs_remove_obj_from_dir(obj);

        /* Now add it */
        list_add(&obj->siblings, &directory->variant.dir_variant.children);
        obj->parent = directory;

        if (directory == obj->my_dev->unlinked_dir
            || directory == obj->my_dev->del_dir) {
                obj->unlinked = 1;
                obj->my_dev->n_unlinked_files++;
                obj->rename_allowed = 0;
        }

        yaffs_verify_dir(directory);
        yaffs_verify_obj_in_dir(obj);
}

static int yaffs_change_obj_name(struct yaffs_obj *obj,
                                 struct yaffs_obj *new_dir,
                                 const YCHAR *new_name, int force, int shadows)
{
        int unlink_op;
        int del_op;
        struct yaffs_obj *existing_target;

        if (new_dir == NULL)
                new_dir = obj->parent;  /* use the old directory */

        if (new_dir->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
                yaffs_trace(YAFFS_TRACE_ALWAYS,
                        "tragedy: yaffs_change_obj_name: new_dir is not a directory"
                        );
                BUG();
        }

        unlink_op = (new_dir == obj->my_dev->unlinked_dir);
        del_op = (new_dir == obj->my_dev->del_dir);

        existing_target = yaffs_find_by_name(new_dir, new_name);

        /* If the object is a file going into the unlinked directory,
         *   then it is OK to just stuff it in since duplicate names are OK.
         *   else only proceed if the new name does not exist and we're putting
         *   it into a directory.
         */
        if (!(unlink_op || del_op || force ||
              shadows > 0 || !existing_target) ||
              new_dir->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY)
                return YAFFS_FAIL;

        yaffs_set_obj_name(obj, new_name);
        obj->dirty = 1;
        yaffs_add_obj_to_dir(new_dir, obj);

        if (unlink_op)
                obj->unlinked = 1;

        /* If it is a deletion then we mark it as a shrink for gc  */
        if (yaffs_update_oh(obj, new_name, 0, del_op, shadows, NULL) >= 0)
                return YAFFS_OK;

        return YAFFS_FAIL;
}

/*------------------------ Short Operations Cache ------------------------------
 *   In many situations where there is no high level buffering  a lot of
 *   reads might be short sequential reads, and a lot of writes may be short
 *   sequential writes. eg. scanning/writing a jpeg file.
 *   In these cases, a short read/write cache can provide a huge perfomance
 *   benefit with dumb-as-a-rock code.
 *   In Linux, the page cache provides read buffering and the short op cache
 *   provides write buffering.
 *
 *   There are a small number (~10) of cache chunks per device so that we don't
 *   need a very intelligent search.
 */

static int yaffs_obj_cache_dirty(struct yaffs_obj *obj)
{
        struct yaffs_dev *dev = obj->my_dev;
        int i;
        struct yaffs_cache *cache;
        int n_caches = obj->my_dev->param.n_caches;

        for (i = 0; i < n_caches; i++) {
                cache = &dev->cache[i];
                if (cache->object == obj && cache->dirty)
                        return 1;
        }

        return 0;
}

static void yaffs_flush_single_cache(struct yaffs_cache *cache, int discard)
{

        if (!cache || cache->locked)
                return;

        /* Write it out and free it up  if need be.*/
        if (cache->dirty) {
                yaffs_wr_data_obj(cache->object,
                                  cache->chunk_id,
                                  cache->data,
                                  cache->n_bytes,
                                  1);

                cache->dirty = 0;
        }

        if (discard)
                cache->object = NULL;
}

static void yaffs_flush_file_cache(struct yaffs_obj *obj, int discard)
{
        struct yaffs_dev *dev = obj->my_dev;
        int i;
        struct yaffs_cache *cache;
        int n_caches = obj->my_dev->param.n_caches;

        if (n_caches < 1)
                return;


        /* Find the chunks for this object and flush them. */
        for (i = 0; i < n_caches; i++) {
                cache = &dev->cache[i];
                if (cache->object == obj)
                        yaffs_flush_single_cache(cache, discard);
        }

}


void yaffs_flush_whole_cache(struct yaffs_dev *dev, int discard)
{
        struct yaffs_obj *obj;
        int n_caches = dev->param.n_caches;
        int i;

        /* Find a dirty object in the cache and flush it...
         * until there are no further dirty objects.
         */
        do {
                obj = NULL;
                for (i = 0; i < n_caches && !obj; i++) {
                        if (dev->cache[i].object && dev->cache[i].dirty)
                                obj = dev->cache[i].object;
                }
                if (obj)
                        yaffs_flush_file_cache(obj, discard);
        } while (obj);

}

/* Grab us an unused cache chunk for use.
 * First look for an empty one.
 * Then look for the least recently used non-dirty one.
 * Then look for the least recently used dirty one...., flush and look again.
 */
static struct yaffs_cache *yaffs_grab_chunk_worker(struct yaffs_dev *dev)
{
        u32 i;

        if (dev->param.n_caches > 0) {
                for (i = 0; i < dev->param.n_caches; i++) {
                        if (!dev->cache[i].object)
                                return &dev->cache[i];
                }
        }

        return NULL;
}

static struct yaffs_cache *yaffs_grab_chunk_cache(struct yaffs_dev *dev)
{
        struct yaffs_cache *cache;
        int usage;
        u32 i;

        if (dev->param.n_caches < 1)
                return NULL;

        /* First look for an unused cache */

        cache = yaffs_grab_chunk_worker(dev);

        if (cache)
                return cache;

        /*
         * Thery were all in use.
         * Find the LRU cache and flush it if it is dirty.
         */

        usage = -1;
        cache = NULL;

        for (i = 0; i < dev->param.n_caches; i++) {
                if (dev->cache[i].object &&
                    !dev->cache[i].locked &&
                    (dev->cache[i].last_use < usage || !cache)) {
                                usage = dev->cache[i].last_use;
                                cache = &dev->cache[i];
                }
        }

#if 1
        yaffs_flush_single_cache(cache, 1);
#else
        yaffs_flush_file_cache(cache->object, 1);
        cache = yaffs_grab_chunk_worker(dev);
#endif

        return cache;
}

/* Find a cached chunk */
static struct yaffs_cache *yaffs_find_chunk_cache(const struct yaffs_obj *obj,
                                                  int chunk_id)
{
        struct yaffs_dev *dev = obj->my_dev;
        u32 i;

        if (dev->param.n_caches < 1)
                return NULL;

        for (i = 0; i < dev->param.n_caches; i++) {
                if (dev->cache[i].object == obj &&
                    dev->cache[i].chunk_id == chunk_id) {
                        dev->cache_hits++;

                        return &dev->cache[i];
                }
        }
        return NULL;
}

/* Mark the chunk for the least recently used algorithym */
static void yaffs_use_cache(struct yaffs_dev *dev, struct yaffs_cache *cache,
                            int is_write)
{
        u32 i;

        if (dev->param.n_caches < 1)
                return;

        if (dev->cache_last_use < 0 ||
                dev->cache_last_use > 100000000) {
                /* Reset the cache usages */
                for (i = 1; i < dev->param.n_caches; i++)
                        dev->cache[i].last_use = 0;

                dev->cache_last_use = 0;
        }
        dev->cache_last_use++;
        cache->last_use = dev->cache_last_use;

        if (is_write)
                cache->dirty = 1;
}

/* Invalidate a single cache page.
 * Do this when a whole page gets written,
 * ie the short cache for this page is no longer valid.
 */
static void yaffs_invalidate_chunk_cache(struct yaffs_obj *object, int chunk_id)
{
        struct yaffs_cache *cache;

        if (object->my_dev->param.n_caches > 0) {
                cache = yaffs_find_chunk_cache(object, chunk_id);

                if (cache)
                        cache->object = NULL;
        }
}

/* Invalidate all the cache pages associated with this object
 * Do this whenever ther file is deleted or resized.
 */
static void yaffs_invalidate_whole_cache(struct yaffs_obj *in)
{
        u32 i;
        struct yaffs_dev *dev = in->my_dev;

        if (dev->param.n_caches > 0) {
                /* Invalidate it. */
                for (i = 0; i < dev->param.n_caches; i++) {
                        if (dev->cache[i].object == in)
                                dev->cache[i].object = NULL;
                }
        }
}

static void yaffs_unhash_obj(struct yaffs_obj *obj)
{
        int bucket;
        struct yaffs_dev *dev = obj->my_dev;

        /* If it is still linked into the bucket list, free from the list */
        if (!list_empty(&obj->hash_link)) {
                list_del_init(&obj->hash_link);
                bucket = yaffs_hash_fn(obj->obj_id);
                dev->obj_bucket[bucket].count--;
        }
}

/*  FreeObject frees up a Object and puts it back on the free list */
static void yaffs_free_obj(struct yaffs_obj *obj)
{
        struct yaffs_dev *dev;

        if (!obj) {
                BUG();
                return;
        }
        dev = obj->my_dev;
        yaffs_trace(YAFFS_TRACE_OS, "FreeObject %p inode %p",
                obj, obj->my_inode);
        if (obj->parent)
                BUG();
        if (!list_empty(&obj->siblings))
                BUG();

        if (obj->my_inode) {
                /* We're still hooked up to a cached inode.
                 * Don't delete now, but mark for later deletion
                 */
                obj->defered_free = 1;
                return;
        }

        yaffs_unhash_obj(obj);

        yaffs_free_raw_obj(dev, obj);
        dev->n_obj--;
        dev->checkpoint_blocks_required = 0;    /* force recalculation */
}

void yaffs_handle_defered_free(struct yaffs_obj *obj)
{
        if (obj->defered_free)
                yaffs_free_obj(obj);
}

static int yaffs_generic_obj_del(struct yaffs_obj *in)
{
        /* Iinvalidate the file's data in the cache, without flushing. */
        yaffs_invalidate_whole_cache(in);

        if (in->my_dev->param.is_yaffs2 && in->parent != in->my_dev->del_dir) {
                /* Move to unlinked directory so we have a deletion record */
                yaffs_change_obj_name(in, in->my_dev->del_dir, _Y("deleted"), 0,
                                      0);
        }

        yaffs_remove_obj_from_dir(in);
        yaffs_chunk_del(in->my_dev, in->hdr_chunk, 1, __LINE__);
        in->hdr_chunk = 0;

        yaffs_free_obj(in);
        return YAFFS_OK;

}

static void yaffs_soft_del_file(struct yaffs_obj *obj)
{
        if (!obj->deleted ||
            obj->variant_type != YAFFS_OBJECT_TYPE_FILE ||
            obj->soft_del)
                return;

        if (obj->n_data_chunks <= 0) {
                /* Empty file with no duplicate object headers,
                 * just delete it immediately */
                yaffs_free_tnode(obj->my_dev, obj->variant.file_variant.top);
                obj->variant.file_variant.top = NULL;
                yaffs_trace(YAFFS_TRACE_TRACING,
                        "yaffs: Deleting empty file %d",
                        obj->obj_id);
                yaffs_generic_obj_del(obj);
        } else {
                yaffs_soft_del_worker(obj,
                                      obj->variant.file_variant.top,
                                      obj->variant.
                                      file_variant.top_level, 0);
                obj->soft_del = 1;
        }
}

/* Pruning removes any part of the file structure tree that is beyond the
 * bounds of the file (ie that does not point to chunks).
 *
 * A file should only get pruned when its size is reduced.
 *
 * Before pruning, the chunks must be pulled from the tree and the
 * level 0 tnode entries must be zeroed out.
 * Could also use this for file deletion, but that's probably better handled
 * by a special case.
 *
 * This function is recursive. For levels > 0 the function is called again on
 * any sub-tree. For level == 0 we just check if the sub-tree has data.
 * If there is no data in a subtree then it is pruned.
 */

static struct yaffs_tnode *yaffs_prune_worker(struct yaffs_dev *dev,
                                              struct yaffs_tnode *tn, u32 level,
                                              int del0)
{
        int i;
        int has_data;

        if (!tn)
                return tn;

        has_data = 0;

        if (level > 0) {
                for (i = 0; i < YAFFS_NTNODES_INTERNAL; i++) {
                        if (tn->internal[i]) {
                                tn->internal[i] =
                                    yaffs_prune_worker(dev,
                                                tn->internal[i],
                                                level - 1,
                                                (i == 0) ? del0 : 1);
                        }

                        if (tn->internal[i])
                                has_data++;
                }
        } else {
                int tnode_size_u32 = dev->tnode_size / sizeof(u32);
                u32 *map = (u32 *) tn;

                for (i = 0; !has_data && i < tnode_size_u32; i++) {
                        if (map[i])
                                has_data++;
                }
        }

        if (has_data == 0 && del0) {
                /* Free and return NULL */
                yaffs_free_tnode(dev, tn);
                tn = NULL;
        }
        return tn;
}

static int yaffs_prune_tree(struct yaffs_dev *dev,
                            struct yaffs_file_var *file_struct)
{
        int i;
        int has_data;
        int done = 0;
        struct yaffs_tnode *tn;

        if (file_struct->top_level < 1)
                return YAFFS_OK;

        file_struct->top =
           yaffs_prune_worker(dev, file_struct->top, file_struct->top_level, 0);

        /* Now we have a tree with all the non-zero branches NULL but
         * the height is the same as it was.
         * Let's see if we can trim internal tnodes to shorten the tree.
         * We can do this if only the 0th element in the tnode is in use
         * (ie all the non-zero are NULL)
         */

        while (file_struct->top_level && !done) {
                tn = file_struct->top;

                has_data = 0;
                for (i = 1; i < YAFFS_NTNODES_INTERNAL; i++) {
                        if (tn->internal[i])
                                has_data++;
                }

                if (!has_data) {
                        file_struct->top = tn->internal[0];
                        file_struct->top_level--;
                        yaffs_free_tnode(dev, tn);
                } else {
                        done = 1;
                }
        }

        return YAFFS_OK;
}

/*-------------------- End of File Structure functions.-------------------*/

/* alloc_empty_obj gets us a clean Object.*/
static struct yaffs_obj *yaffs_alloc_empty_obj(struct yaffs_dev *dev)
{
        struct yaffs_obj *obj = yaffs_alloc_raw_obj(dev);

        if (!obj)
                return obj;

        dev->n_obj++;

        /* Now sweeten it up... */

        memset(obj, 0, sizeof(struct yaffs_obj));
        obj->being_created = 1;

        obj->my_dev = dev;
        obj->hdr_chunk = 0;
        obj->variant_type = YAFFS_OBJECT_TYPE_UNKNOWN;
        INIT_LIST_HEAD(&(obj->hard_links));
        INIT_LIST_HEAD(&(obj->hash_link));
        INIT_LIST_HEAD(&obj->siblings);

        /* Now make the directory sane */
        if (dev->root_dir) {
                obj->parent = dev->root_dir;
                list_add(&(obj->siblings),
                         &dev->root_dir->variant.dir_variant.children);
        }

        /* Add it to the lost and found directory.
         * NB Can't put root or lost-n-found in lost-n-found so
         * check if lost-n-found exists first
         */
        if (dev->lost_n_found)
                yaffs_add_obj_to_dir(dev->lost_n_found, obj);

        obj->being_created = 0;

        dev->checkpoint_blocks_required = 0;    /* force recalculation */

        return obj;
}

static int yaffs_find_nice_bucket(struct yaffs_dev *dev)
{
        int i;
        int l = 999;
        int lowest = 999999;

        /* Search for the shortest list or one that
         * isn't too long.
         */

        for (i = 0; i < 10 && lowest > 4; i++) {
                dev->bucket_finder++;
                dev->bucket_finder %= YAFFS_NOBJECT_BUCKETS;
                if (dev->obj_bucket[dev->bucket_finder].count < lowest) {
                        lowest = dev->obj_bucket[dev->bucket_finder].count;
                        l = dev->bucket_finder;
                }
        }

        return l;
}

static int yaffs_new_obj_id(struct yaffs_dev *dev)
{
        int bucket = yaffs_find_nice_bucket(dev);
        int found = 0;
        struct list_head *i;
        u32 n = (u32) bucket;

        /*
         * Now find an object value that has not already been taken
         * by scanning the list, incrementing each time by number of buckets.
         */
        while (!found) {
                found = 1;
                n += YAFFS_NOBJECT_BUCKETS;
                list_for_each(i, &dev->obj_bucket[bucket].list) {
                        /* Check if this value is already taken. */
                        if (i && list_entry(i, struct yaffs_obj,
                                            hash_link)->obj_id == n)
                                found = 0;
                }
        }
        return n;
}

static void yaffs_hash_obj(struct yaffs_obj *in)
{
        int bucket = yaffs_hash_fn(in->obj_id);
        struct yaffs_dev *dev = in->my_dev;

        list_add(&in->hash_link, &dev->obj_bucket[bucket].list);
        dev->obj_bucket[bucket].count++;
}

struct yaffs_obj *yaffs_find_by_number(struct yaffs_dev *dev, u32 number)
{
        int bucket = yaffs_hash_fn(number);
        struct list_head *i;
        struct yaffs_obj *in;

        list_for_each(i, &dev->obj_bucket[bucket].list) {
                /* Look if it is in the list */
                in = list_entry(i, struct yaffs_obj, hash_link);
                if (in->obj_id == number) {
                        /* Don't show if it is defered free */
                        if (in->defered_free)
                                return NULL;
                        return in;
                }
        }

        return NULL;
}

static struct yaffs_obj *yaffs_new_obj(struct yaffs_dev *dev, int number,
                                enum yaffs_obj_type type)
{
        struct yaffs_obj *the_obj = NULL;
        struct yaffs_tnode *tn = NULL;

        if (number < 0)
                number = yaffs_new_obj_id(dev);

        if (type == YAFFS_OBJECT_TYPE_FILE) {
                tn = yaffs_get_tnode(dev);
                if (!tn)
                        return NULL;
        }

        the_obj = yaffs_alloc_empty_obj(dev);
        if (!the_obj) {
                if (tn)
                        yaffs_free_tnode(dev, tn);
                return NULL;
        }

        the_obj->fake = 0;
        the_obj->rename_allowed = 1;
        the_obj->unlink_allowed = 1;
        the_obj->obj_id = number;
        yaffs_hash_obj(the_obj);
        the_obj->variant_type = type;
        yaffs_load_current_time(the_obj, 1, 1);

        switch (type) {
        case YAFFS_OBJECT_TYPE_FILE:
                the_obj->variant.file_variant.file_size = 0;
                the_obj->variant.file_variant.stored_size = 0;
                the_obj->variant.file_variant.shrink_size =
                                                yaffs_max_file_size(dev);
                the_obj->variant.file_variant.top_level = 0;
                the_obj->variant.file_variant.top = tn;
                break;
        case YAFFS_OBJECT_TYPE_DIRECTORY:
                INIT_LIST_HEAD(&the_obj->variant.dir_variant.children);
                INIT_LIST_HEAD(&the_obj->variant.dir_variant.dirty);
                break;
        case YAFFS_OBJECT_TYPE_SYMLINK:
        case YAFFS_OBJECT_TYPE_HARDLINK:
        case YAFFS_OBJECT_TYPE_SPECIAL:
                /* No action required */
                break;
        case YAFFS_OBJECT_TYPE_UNKNOWN:
                /* todo this should not happen */
                break;
        }
        return the_obj;
}

static struct yaffs_obj *yaffs_create_fake_dir(struct yaffs_dev *dev,
                                               int number, u32 mode)
{

        struct yaffs_obj *obj =
            yaffs_new_obj(dev, number, YAFFS_OBJECT_TYPE_DIRECTORY);

        if (!obj)
                return NULL;

        obj->fake = 1;  /* it is fake so it might not use NAND */
        obj->rename_allowed = 0;
        obj->unlink_allowed = 0;
        obj->deleted = 0;
        obj->unlinked = 0;
        obj->yst_mode = mode;
        obj->my_dev = dev;
        obj->hdr_chunk = 0;     /* Not a valid chunk. */
        return obj;

}


static void yaffs_init_tnodes_and_objs(struct yaffs_dev *dev)
{
        int i;

        dev->n_obj = 0;
        dev->n_tnodes = 0;
        yaffs_init_raw_tnodes_and_objs(dev);

        for (i = 0; i < YAFFS_NOBJECT_BUCKETS; i++) {
                INIT_LIST_HEAD(&dev->obj_bucket[i].list);
                dev->obj_bucket[i].count = 0;
        }
}

struct yaffs_obj *yaffs_find_or_create_by_number(struct yaffs_dev *dev,
                                                 int number,
                                                 enum yaffs_obj_type type)
{
        struct yaffs_obj *the_obj = NULL;

        if (number > 0)
                the_obj = yaffs_find_by_number(dev, number);

        if (!the_obj)
                the_obj = yaffs_new_obj(dev, number, type);

        return the_obj;

}

YCHAR *yaffs_clone_str(const YCHAR *str)
{
        YCHAR *new_str = NULL;
        int len;

        if (!str)
                str = _Y("");

        len = strnlen(str, YAFFS_MAX_ALIAS_LENGTH);
        new_str = kmalloc((len + 1) * sizeof(YCHAR), GFP_NOFS);
        if (new_str) {
                strncpy(new_str, str, len);
                new_str[len] = 0;
        }
        return new_str;

}
/*
 *yaffs_update_parent() handles fixing a directories mtime and ctime when a new
 * link (ie. name) is created or deleted in the directory.
 *
 * ie.
 *   create dir/a : update dir's mtime/ctime
 *   rm dir/a:   update dir's mtime/ctime
 *   modify dir/a: don't update dir's mtimme/ctime
 *
 * This can be handled immediately or defered. Defering helps reduce the number
 * of updates when many files in a directory are changed within a brief period.
 *
 * If the directory updating is defered then yaffs_update_dirty_dirs must be
 * called periodically.
 */

static void yaffs_update_parent(struct yaffs_obj *obj)
{
        struct yaffs_dev *dev;

        if (!obj)
                return;
        dev = obj->my_dev;
        obj->dirty = 1;
        yaffs_load_current_time(obj, 0, 1);
        if (dev->param.defered_dir_update) {
                struct list_head *link = &obj->variant.dir_variant.dirty;

                if (list_empty(link)) {
                        list_add(link, &dev->dirty_dirs);
                        yaffs_trace(YAFFS_TRACE_BACKGROUND,
                          "Added object %d to dirty directories",
                           obj->obj_id);
                }

        } else {
                yaffs_update_oh(obj, NULL, 0, 0, 0, NULL);
        }
}

void yaffs_update_dirty_dirs(struct yaffs_dev *dev)
{
        struct list_head *link;
        struct yaffs_obj *obj;
        struct yaffs_dir_var *d_s;
        union yaffs_obj_var *o_v;

        yaffs_trace(YAFFS_TRACE_BACKGROUND, "Update dirty directories");

        while (!list_empty(&dev->dirty_dirs)) {
                link = dev->dirty_dirs.next;
                list_del_init(link);

                d_s = list_entry(link, struct yaffs_dir_var, dirty);
                o_v = list_entry(d_s, union yaffs_obj_var, dir_variant);
                obj = list_entry(o_v, struct yaffs_obj, variant);

                yaffs_trace(YAFFS_TRACE_BACKGROUND, "Update directory %d",
                        obj->obj_id);

                if (obj->dirty)
                        yaffs_update_oh(obj, NULL, 0, 0, 0, NULL);
        }
}

/*
 * Mknod (create) a new object.
 * equiv_obj only has meaning for a hard link;
 * alias_str only has meaning for a symlink.
 * rdev only has meaning for devices (a subset of special objects)
 */

static struct yaffs_obj *yaffs_create_obj(enum yaffs_obj_type type,
                                          struct yaffs_obj *parent,
                                          const YCHAR *name,
                                          u32 mode,
                                          u32 uid,
                                          u32 gid,
                                          struct yaffs_obj *equiv_obj,
                                          const YCHAR *alias_str, u32 rdev)
{
        struct yaffs_obj *in;
        YCHAR *str = NULL;
        struct yaffs_dev *dev = parent->my_dev;

        /* Check if the entry exists.
         * If it does then fail the call since we don't want a dup. */
        if (yaffs_find_by_name(parent, name))
                return NULL;

        if (type == YAFFS_OBJECT_TYPE_SYMLINK) {
                str = yaffs_clone_str(alias_str);
                if (!str)
                        return NULL;
        }

        in = yaffs_new_obj(dev, -1, type);

        if (!in) {
                kfree(str);
                return NULL;
        }

        in->hdr_chunk = 0;
        in->valid = 1;
        in->variant_type = type;

        in->yst_mode = mode;

        yaffs_attribs_init(in, gid, uid, rdev);

        in->n_data_chunks = 0;

        yaffs_set_obj_name(in, name);
        in->dirty = 1;

        yaffs_add_obj_to_dir(parent, in);

        in->my_dev = parent->my_dev;

        switch (type) {
        case YAFFS_OBJECT_TYPE_SYMLINK:
                in->variant.symlink_variant.alias = str;
                break;
        case YAFFS_OBJECT_TYPE_HARDLINK:
                in->variant.hardlink_variant.equiv_obj = equiv_obj;
                in->variant.hardlink_variant.equiv_id = equiv_obj->obj_id;
                list_add(&in->hard_links, &equiv_obj->hard_links);
                break;
        case YAFFS_OBJECT_TYPE_FILE:
        case YAFFS_OBJECT_TYPE_DIRECTORY:
        case YAFFS_OBJECT_TYPE_SPECIAL:
        case YAFFS_OBJECT_TYPE_UNKNOWN:
                /* do nothing */
                break;
        }

        if (yaffs_update_oh(in, name, 0, 0, 0, NULL) < 0) {
                /* Could not create the object header, fail */
                yaffs_del_obj(in);
                in = NULL;
        }

        if (in)
                yaffs_update_parent(parent);

        return in;
}

struct yaffs_obj *yaffs_create_file(struct yaffs_obj *parent,
                                    const YCHAR *name, u32 mode, u32 uid,
                                    u32 gid)
{
        return yaffs_create_obj(YAFFS_OBJECT_TYPE_FILE, parent, name, mode,
                                uid, gid, NULL, NULL, 0);
}

struct yaffs_obj *yaffs_create_dir(struct yaffs_obj *parent, const YCHAR *name,
                                   u32 mode, u32 uid, u32 gid)
{
        return yaffs_create_obj(YAFFS_OBJECT_TYPE_DIRECTORY, parent, name,
                                mode, uid, gid, NULL, NULL, 0);
}

struct yaffs_obj *yaffs_create_special(struct yaffs_obj *parent,
                                       const YCHAR *name, u32 mode, u32 uid,
                                       u32 gid, u32 rdev)
{
        return yaffs_create_obj(YAFFS_OBJECT_TYPE_SPECIAL, parent, name, mode,
                                uid, gid, NULL, NULL, rdev);
}

struct yaffs_obj *yaffs_create_symlink(struct yaffs_obj *parent,
                                       const YCHAR *name, u32 mode, u32 uid,
                                       u32 gid, const YCHAR *alias)
{
        return yaffs_create_obj(YAFFS_OBJECT_TYPE_SYMLINK, parent, name, mode,
                                uid, gid, NULL, alias, 0);
}

/* yaffs_link_obj returns the object id of the equivalent object.*/
struct yaffs_obj *yaffs_link_obj(struct yaffs_obj *parent, const YCHAR * name,
                                 struct yaffs_obj *equiv_obj)
{
        /* Get the real object in case we were fed a hard link obj */
        equiv_obj = yaffs_get_equivalent_obj(equiv_obj);

        if (yaffs_create_obj(YAFFS_OBJECT_TYPE_HARDLINK,
                        parent, name, 0, 0, 0,
                        equiv_obj, NULL, 0))
                return equiv_obj;

        return NULL;

}



/*---------------------- Block Management and Page Allocation -------------*/

static void yaffs_deinit_blocks(struct yaffs_dev *dev)
{
        if (dev->block_info_alt && dev->block_info)
                vfree(dev->block_info);
        else
                kfree(dev->block_info);

        dev->block_info_alt = 0;

        dev->block_info = NULL;

        if (dev->chunk_bits_alt && dev->chunk_bits)
                vfree(dev->chunk_bits);
        else
                kfree(dev->chunk_bits);
        dev->chunk_bits_alt = 0;
        dev->chunk_bits = NULL;
}

static int yaffs_init_blocks(struct yaffs_dev *dev)
{
        int n_blocks = dev->internal_end_block - dev->internal_start_block + 1;

        dev->block_info = NULL;
        dev->chunk_bits = NULL;
        dev->alloc_block = -1;  /* force it to get a new one */

        /* If the first allocation strategy fails, thry the alternate one */
        dev->block_info =
                kmalloc(n_blocks * sizeof(struct yaffs_block_info), GFP_NOFS);
        if (!dev->block_info) {
                dev->block_info =
                    vmalloc(n_blocks * sizeof(struct yaffs_block_info));
                dev->block_info_alt = 1;
        } else {
                dev->block_info_alt = 0;
        }

        if (!dev->block_info)
                goto alloc_error;

        /* Set up dynamic blockinfo stuff. Round up bytes. */
        dev->chunk_bit_stride = (dev->param.chunks_per_block + 7) / 8;
        dev->chunk_bits =
                kmalloc(dev->chunk_bit_stride * n_blocks, GFP_NOFS);
        if (!dev->chunk_bits) {
                dev->chunk_bits =
                    vmalloc(dev->chunk_bit_stride * n_blocks);
                dev->chunk_bits_alt = 1;
        } else {
                dev->chunk_bits_alt = 0;
        }
        if (!dev->chunk_bits)
                goto alloc_error;


        memset(dev->block_info, 0, n_blocks * sizeof(struct yaffs_block_info));
        memset(dev->chunk_bits, 0, dev->chunk_bit_stride * n_blocks);
        return YAFFS_OK;

alloc_error:
        yaffs_deinit_blocks(dev);
        return YAFFS_FAIL;
}


void yaffs_block_became_dirty(struct yaffs_dev *dev, int block_no)
{
        struct yaffs_block_info *bi = yaffs_get_block_info(dev, block_no);
        int erased_ok = 0;
        u32 i;

        /* If the block is still healthy erase it and mark as clean.
         * If the block has had a data failure, then retire it.
         */

        yaffs_trace(YAFFS_TRACE_GC | YAFFS_TRACE_ERASE,
                "yaffs_block_became_dirty block %d state %d %s",
                block_no, bi->block_state,
                (bi->needs_retiring) ? "needs retiring" : "");

        yaffs2_clear_oldest_dirty_seq(dev, bi);

        bi->block_state = YAFFS_BLOCK_STATE_DIRTY;

        /* If this is the block being garbage collected then stop gc'ing */
        if (block_no == (int)dev->gc_block)
                dev->gc_block = 0;

        /* If this block is currently the best candidate for gc
         * then drop as a candidate */
        if (block_no == (int)dev->gc_dirtiest) {
                dev->gc_dirtiest = 0;
                dev->gc_pages_in_use = 0;
        }

        if (!bi->needs_retiring) {
                yaffs2_checkpt_invalidate(dev);
                erased_ok = yaffs_erase_block(dev, block_no);
                if (!erased_ok) {
                        dev->n_erase_failures++;
                        yaffs_trace(YAFFS_TRACE_ERROR | YAFFS_TRACE_BAD_BLOCKS,
                          "**>> Erasure failed %d", block_no);
                }
        }

        /* Verify erasure if needed */
        if (erased_ok &&
            ((yaffs_trace_mask & YAFFS_TRACE_ERASE) ||
             !yaffs_skip_verification(dev))) {
                for (i = 0; i < dev->param.chunks_per_block; i++) {
                        if (!yaffs_check_chunk_erased(dev,
                                block_no * dev->param.chunks_per_block + i)) {
                                yaffs_trace(YAFFS_TRACE_ERROR,
                                        ">>Block %d erasure supposedly OK, but chunk %d not erased",
                                        block_no, i);
                        }
                }
        }

        if (!erased_ok) {
                /* We lost a block of free space */
                dev->n_free_chunks -= dev->param.chunks_per_block;
                yaffs_retire_block(dev, block_no);
                yaffs_trace(YAFFS_TRACE_ERROR | YAFFS_TRACE_BAD_BLOCKS,
                        "**>> Block %d retired", block_no);
                return;
        }

        /* Clean it up... */
        bi->block_state = YAFFS_BLOCK_STATE_EMPTY;
        bi->seq_number = 0;
        dev->n_erased_blocks++;
        bi->pages_in_use = 0;
        bi->soft_del_pages = 0;
        bi->has_shrink_hdr = 0;
        bi->skip_erased_check = 1;      /* Clean, so no need to check */
        bi->gc_prioritise = 0;
        bi->has_summary = 0;

        yaffs_clear_chunk_bits(dev, block_no);

        yaffs_trace(YAFFS_TRACE_ERASE, "Erased block %d", block_no);
}

static inline int yaffs_gc_process_chunk(struct yaffs_dev *dev,
                                        struct yaffs_block_info *bi,
                                        int old_chunk, u8 *buffer)
{
        int new_chunk;
        int mark_flash = 1;
        struct yaffs_ext_tags tags;
        struct yaffs_obj *object;
        int matching_chunk;
        int ret_val = YAFFS_OK;

        memset(&tags, 0, sizeof(tags));
        yaffs_rd_chunk_tags_nand(dev, old_chunk,
                                 buffer, &tags);
        object = yaffs_find_by_number(dev, tags.obj_id);

        yaffs_trace(YAFFS_TRACE_GC_DETAIL,
                "Collecting chunk in block %d, %d %d %d ",
                dev->gc_chunk, tags.obj_id,
                tags.chunk_id, tags.n_bytes);

        if (object && !yaffs_skip_verification(dev)) {
                if (tags.chunk_id == 0)
                        matching_chunk =
                            object->hdr_chunk;
                else if (object->soft_del)
                        /* Defeat the test */
                        matching_chunk = old_chunk;
                else
                        matching_chunk =
                            yaffs_find_chunk_in_file
                            (object, tags.chunk_id,
                             NULL);

                if (old_chunk != matching_chunk)
                        yaffs_trace(YAFFS_TRACE_ERROR,
                                "gc: page in gc mismatch: %d %d %d %d",
                                old_chunk,
                                matching_chunk,
                                tags.obj_id,
                                tags.chunk_id);
        }

        if (!object) {
                yaffs_trace(YAFFS_TRACE_ERROR,
                        "page %d in gc has no object: %d %d %d ",
                        old_chunk,
                        tags.obj_id, tags.chunk_id,
                        tags.n_bytes);
        }

        if (object &&
            object->deleted &&
            object->soft_del && tags.chunk_id != 0) {
                /* Data chunk in a soft deleted file,
                 * throw it away.
                 * It's a soft deleted data chunk,
                 * No need to copy this, just forget
                 * about it and fix up the object.
                 */

                /* Free chunks already includes
                 * softdeleted chunks, how ever this
                 * chunk is going to soon be really
                 * deleted which will increment free
                 * chunks. We have to decrement free
                 * chunks so this works out properly.
                 */
                dev->n_free_chunks--;
                bi->soft_del_pages--;

                object->n_data_chunks--;
                if (object->n_data_chunks <= 0) {
                        /* remeber to clean up obj */
                        dev->gc_cleanup_list[dev->n_clean_ups] = tags.obj_id;
                        dev->n_clean_ups++;
                }
                mark_flash = 0;
        } else if (object) {
                /* It's either a data chunk in a live
                 * file or an ObjectHeader, so we're
                 * interested in it.
                 * NB Need to keep the ObjectHeaders of
                 * deleted files until the whole file
                 * has been deleted off
                 */
                tags.serial_number++;
                dev->n_gc_copies++;

                if (tags.chunk_id == 0) {
                        /* It is an object Id,
                         * We need to nuke the shrinkheader flags since its
                         * work is done.
                         * Also need to clean up shadowing.
                         * NB We don't want to do all the work of translating
                         * object header endianism back and forth so we leave
                         * the oh endian in its stored order.
                         */

                        struct yaffs_obj_hdr *oh;
                        oh = (struct yaffs_obj_hdr *) buffer;

                        oh->is_shrink = 0;
                        tags.extra_is_shrink = 0;
                        oh->shadows_obj = 0;
                        oh->inband_shadowed_obj_id = 0;
                        tags.extra_shadows = 0;

                        /* Update file size */
                        if (object->variant_type == YAFFS_OBJECT_TYPE_FILE) {
                                yaffs_oh_size_load(dev, oh,
                                    object->variant.file_variant.stored_size, 1);
                                tags.extra_file_size =
                                    object->variant.file_variant.stored_size;
                        }

                        yaffs_verify_oh(object, oh, &tags, 1);
                        new_chunk =
                            yaffs_write_new_chunk(dev, (u8 *) oh, &tags, 1);
                } else {
                        new_chunk =
                            yaffs_write_new_chunk(dev, buffer, &tags, 1);
                }

                if (new_chunk < 0) {
                        ret_val = YAFFS_FAIL;
                } else {

                        /* Now fix up the Tnodes etc. */

                        if (tags.chunk_id == 0) {
                                /* It's a header */
                                object->hdr_chunk = new_chunk;
                                object->serial = tags.serial_number;
                        } else {
                                /* It's a data chunk */
                                yaffs_put_chunk_in_file(object, tags.chunk_id,
                                                        new_chunk, 0);
                        }
                }
        }
        if (ret_val == YAFFS_OK)
                yaffs_chunk_del(dev, old_chunk, mark_flash, __LINE__);
        return ret_val;
}

static int yaffs_gc_block(struct yaffs_dev *dev, int block, int whole_block)
{
        int old_chunk;
        int ret_val = YAFFS_OK;
        u32 i;
        int is_checkpt_block;
        int max_copies;
        int chunks_before = yaffs_get_erased_chunks(dev);
        int chunks_after;
        struct yaffs_block_info *bi = yaffs_get_block_info(dev, block);

        is_checkpt_block = (bi->block_state == YAFFS_BLOCK_STATE_CHECKPOINT);

        yaffs_trace(YAFFS_TRACE_TRACING,
                "Collecting block %d, in use %d, shrink %d, whole_block %d",
                block, bi->pages_in_use, bi->has_shrink_hdr,
                whole_block);

        /*yaffs_verify_free_chunks(dev); */

        if (bi->block_state == YAFFS_BLOCK_STATE_FULL)
                bi->block_state = YAFFS_BLOCK_STATE_COLLECTING;

        bi->has_shrink_hdr = 0; /* clear the flag so that the block can erase */

        dev->gc_disable = 1;

        yaffs_summary_gc(dev, block);

        if (is_checkpt_block || !yaffs_still_some_chunks(dev, block)) {
                yaffs_trace(YAFFS_TRACE_TRACING,
                        "Collecting block %d that has no chunks in use",
                        block);
                yaffs_block_became_dirty(dev, block);
        } else {

                u8 *buffer = yaffs_get_temp_buffer(dev);

                yaffs_verify_blk(dev, bi, block);

                max_copies = (whole_block) ? dev->param.chunks_per_block : 5;
                old_chunk = block * dev->param.chunks_per_block + dev->gc_chunk;

                for (/* init already done */ ;
                     ret_val == YAFFS_OK &&
                     dev->gc_chunk < dev->param.chunks_per_block &&
                     (bi->block_state == YAFFS_BLOCK_STATE_COLLECTING) &&
                     max_copies > 0;
                     dev->gc_chunk++, old_chunk++) {
                        if (yaffs_check_chunk_bit(dev, block, dev->gc_chunk)) {
                                /* Page is in use and might need to be copied */
                                max_copies--;
                                ret_val = yaffs_gc_process_chunk(dev, bi,
                                                        old_chunk, buffer);
                        }
                }
                yaffs_release_temp_buffer(dev, buffer);
        }

        yaffs_verify_collected_blk(dev, bi, block);

        if (bi->block_state == YAFFS_BLOCK_STATE_COLLECTING) {
                /*
                 * The gc did not complete. Set block state back to FULL
                 * because checkpointing does not restore gc.
                 */
                bi->block_state = YAFFS_BLOCK_STATE_FULL;
        } else {
                /* The gc completed. */
                /* Do any required cleanups */
                for (i = 0; i < dev->n_clean_ups; i++) {
                        /* Time to delete the file too */
                        struct yaffs_obj *object =
                            yaffs_find_by_number(dev, dev->gc_cleanup_list[i]);
                        if (object) {
                                yaffs_free_tnode(dev,
                                          object->variant.file_variant.top);
                                object->variant.file_variant.top = NULL;
                                yaffs_trace(YAFFS_TRACE_GC,
                                        "yaffs: About to finally delete object %d",
                                        object->obj_id);
                                yaffs_generic_obj_del(object);
                                object->my_dev->n_deleted_files--;
                        }

                }
                chunks_after = yaffs_get_erased_chunks(dev);
                if (chunks_before >= chunks_after)
                        yaffs_trace(YAFFS_TRACE_GC,
                                "gc did not increase free chunks before %d after %d",
                                chunks_before, chunks_after);
                dev->gc_block = 0;
                dev->gc_chunk = 0;
                dev->n_clean_ups = 0;
        }

        dev->gc_disable = 0;

        return ret_val;
}

/*
 * find_gc_block() selects the dirtiest block (or close enough)
 * for garbage collection.
 */

static unsigned yaffs_find_gc_block(struct yaffs_dev *dev,
                                    int aggressive, int background)
{
        u32 i;
        u32 iterations;
        u32 selected = 0;
        int prioritised = 0;
        int prioritised_exist = 0;
        struct yaffs_block_info *bi;
        u32 threshold;

        /* First let's see if we need to grab a prioritised block */
        if (dev->has_pending_prioritised_gc && !aggressive) {
                dev->gc_dirtiest = 0;
                bi = dev->block_info;
                for (i = dev->internal_start_block;
                     i <= dev->internal_end_block && !selected; i++) {

                        if (bi->gc_prioritise) {
                                prioritised_exist = 1;
                                if (bi->block_state == YAFFS_BLOCK_STATE_FULL &&
                                    yaffs_block_ok_for_gc(dev, bi)) {
                                        selected = i;
                                        prioritised = 1;
                                }
                        }
                        bi++;
                }

                /*
                 * If there is a prioritised block and none was selected then
                 * this happened because there is at least one old dirty block
                 * gumming up the works. Let's gc the oldest dirty block.
                 */

                if (prioritised_exist &&
                    !selected && dev->oldest_dirty_block > 0)
                        selected = dev->oldest_dirty_block;

                if (!prioritised_exist) /* None found, so we can clear this */
                        dev->has_pending_prioritised_gc = 0;
        }

        /* If we're doing aggressive GC then we are happy to take a less-dirty
         * block, and search harder.
         * else (leasurely gc), then we only bother to do this if the
         * block has only a few pages in use.
         */

        if (!selected) {
                u32 pages_used;
                int n_blocks =
                    dev->internal_end_block - dev->internal_start_block + 1;
                if (aggressive) {
                        threshold = dev->param.chunks_per_block;
                        iterations = n_blocks;
                } else {
                        u32 max_threshold;

                        if (background)
                                max_threshold = dev->param.chunks_per_block / 2;
                        else
                                max_threshold = dev->param.chunks_per_block / 8;

                        if (max_threshold < YAFFS_GC_PASSIVE_THRESHOLD)
                                max_threshold = YAFFS_GC_PASSIVE_THRESHOLD;

                        threshold = background ? (dev->gc_not_done + 2) * 2 : 0;
                        if (threshold < YAFFS_GC_PASSIVE_THRESHOLD)
                                threshold = YAFFS_GC_PASSIVE_THRESHOLD;
                        if (threshold > max_threshold)
                                threshold = max_threshold;

                        iterations = n_blocks / 16 + 1;
                        if (iterations > 100)
                                iterations = 100;
                }

                for (i = 0;
                     i < iterations &&
                     (dev->gc_dirtiest < 1 ||
                      dev->gc_pages_in_use > YAFFS_GC_GOOD_ENOUGH);
                     i++) {
                        dev->gc_block_finder++;
                        if (dev->gc_block_finder < dev->internal_start_block ||
                            dev->gc_block_finder > dev->internal_end_block)
                                dev->gc_block_finder =
                                    dev->internal_start_block;

                        bi = yaffs_get_block_info(dev, dev->gc_block_finder);

                        pages_used = bi->pages_in_use - bi->soft_del_pages;

                        if (bi->block_state == YAFFS_BLOCK_STATE_FULL &&
                            pages_used < dev->param.chunks_per_block &&
                            (dev->gc_dirtiest < 1 ||
                             pages_used < dev->gc_pages_in_use) &&
                            yaffs_block_ok_for_gc(dev, bi)) {
                                dev->gc_dirtiest = dev->gc_block_finder;
                                dev->gc_pages_in_use = pages_used;
                        }
                }

                if (dev->gc_dirtiest > 0 && dev->gc_pages_in_use <= threshold)
                        selected = dev->gc_dirtiest;
        }

        /*
         * If nothing has been selected for a while, try the oldest dirty
         * because that's gumming up the works.
         */

        if (!selected && dev->param.is_yaffs2 &&
            dev->gc_not_done >= (background ? 10 : 20)) {
                yaffs2_find_oldest_dirty_seq(dev);
                if (dev->oldest_dirty_block > 0) {
                        selected = dev->oldest_dirty_block;
                        dev->gc_dirtiest = selected;
                        dev->oldest_dirty_gc_count++;
                        bi = yaffs_get_block_info(dev, selected);
                        dev->gc_pages_in_use =
                            bi->pages_in_use - bi->soft_del_pages;
                } else {
                        dev->gc_not_done = 0;
                }
        }

        if (selected) {
                yaffs_trace(YAFFS_TRACE_GC,
                        "GC Selected block %d with %d free, prioritised:%d",
                        selected,
                        dev->param.chunks_per_block - dev->gc_pages_in_use,
                        prioritised);

                dev->n_gc_blocks++;
                if (background)
                        dev->bg_gcs++;

                dev->gc_dirtiest = 0;
                dev->gc_pages_in_use = 0;
                dev->gc_not_done = 0;
                if (dev->refresh_skip > 0)
                        dev->refresh_skip--;
        } else {
                dev->gc_not_done++;
                yaffs_trace(YAFFS_TRACE_GC,
                        "GC none: finder %d skip %d threshold %d dirtiest %d using %d oldest %d%s",
                        dev->gc_block_finder, dev->gc_not_done, threshold,
                        dev->gc_dirtiest, dev->gc_pages_in_use,
                        dev->oldest_dirty_block, background ? " bg" : "");
        }

        return selected;
}

/* New garbage collector
 * If we're very low on erased blocks then we do aggressive garbage collection
 * otherwise we do "leasurely" garbage collection.
 * Aggressive gc looks further (whole array) and will accept less dirty blocks.
 * Passive gc only inspects smaller areas and only accepts more dirty blocks.
 *
 * The idea is to help clear out space in a more spread-out manner.
 * Dunno if it really does anything useful.
 */
static int yaffs_check_gc(struct yaffs_dev *dev, int background)
{
        int aggressive = 0;
        int gc_ok = YAFFS_OK;
        int max_tries = 0;
        int min_erased;
        int erased_chunks;
        int checkpt_block_adjust;

        if (dev->param.gc_control_fn &&
                (dev->param.gc_control_fn(dev) & 1) == 0)
                return YAFFS_OK;

        if (dev->gc_disable)
                /* Bail out so we don't get recursive gc */
                return YAFFS_OK;

        /* This loop should pass the first time.
         * Only loops here if the collection does not increase space.
         */

        do {
                max_tries++;

                checkpt_block_adjust = yaffs_calc_checkpt_blocks_required(dev);

                min_erased =
                    dev->param.n_reserved_blocks + checkpt_block_adjust + 1;
                erased_chunks =
                    dev->n_erased_blocks * dev->param.chunks_per_block;

                /* If we need a block soon then do aggressive gc. */
                if (dev->n_erased_blocks < min_erased)
                        aggressive = 1;
                else {
                        if (!background
                            && erased_chunks > (dev->n_free_chunks / 4))
                                break;

                        if (dev->gc_skip > 20)
                                dev->gc_skip = 20;
                        if (erased_chunks < dev->n_free_chunks / 2 ||
                            dev->gc_skip < 1 || background)
                                aggressive = 0;
                        else {
                                dev->gc_skip--;
                                break;
                        }
                }

                dev->gc_skip = 5;

                /* If we don't already have a block being gc'd then see if we
                 * should start another */

                if (dev->gc_block < 1 && !aggressive) {
                        dev->gc_block = yaffs2_find_refresh_block(dev);
                        dev->gc_chunk = 0;
                        dev->n_clean_ups = 0;
                }
                if (dev->gc_block < 1) {
                        dev->gc_block =
                            yaffs_find_gc_block(dev, aggressive, background);
                        dev->gc_chunk = 0;
                        dev->n_clean_ups = 0;
                }

                if (dev->gc_block > 0) {
                        dev->all_gcs++;
                        if (!aggressive)
                                dev->passive_gc_count++;

                        yaffs_trace(YAFFS_TRACE_GC,
                                "yaffs: GC n_erased_blocks %d aggressive %d",
                                dev->n_erased_blocks, aggressive);

                        gc_ok = yaffs_gc_block(dev, dev->gc_block, aggressive);
                }

                if (dev->n_erased_blocks < (int)dev->param.n_reserved_blocks &&
                    dev->gc_block > 0) {
                        yaffs_trace(YAFFS_TRACE_GC,
                                "yaffs: GC !!!no reclaim!!! n_erased_blocks %d after try %d block %d",
                                dev->n_erased_blocks, max_tries,
                                dev->gc_block);
                }
        } while ((dev->n_erased_blocks < (int)dev->param.n_reserved_blocks) &&
                 (dev->gc_block > 0) && (max_tries < 2));

        return aggressive ? gc_ok : YAFFS_OK;
}

/*
 * yaffs_bg_gc()
 * Garbage collects. Intended to be called from a background thread.
 * Returns non-zero if at least half the free chunks are erased.
 */
int yaffs_bg_gc(struct yaffs_dev *dev, unsigned urgency)
{
        int erased_chunks = dev->n_erased_blocks * dev->param.chunks_per_block;

        yaffs_trace(YAFFS_TRACE_BACKGROUND, "Background gc %u", urgency);

        yaffs_check_gc(dev, 1);
        return erased_chunks > dev->n_free_chunks / 2;
}

/*-------------------- Data file manipulation -----------------*/

static int yaffs_rd_data_obj(struct yaffs_obj *in, int inode_chunk, u8 * buffer)
{
        int nand_chunk = yaffs_find_chunk_in_file(in, inode_chunk, NULL);

        if (nand_chunk >= 0)
                return yaffs_rd_chunk_tags_nand(in->my_dev, nand_chunk,
                                                buffer, NULL);
        else {
                yaffs_trace(YAFFS_TRACE_NANDACCESS,
                        "Chunk %d not found zero instead",
                        nand_chunk);
                /* get sane (zero) data if you read a hole */
                memset(buffer, 0, in->my_dev->data_bytes_per_chunk);
                return 0;
        }

}

void yaffs_chunk_del(struct yaffs_dev *dev, int chunk_id, int mark_flash,
                     int lyn)
{
        int block;
        int page;
        struct yaffs_ext_tags tags;
        struct yaffs_block_info *bi;

        if (chunk_id <= 0)
                return;

        dev->n_deletions++;
        block = chunk_id / dev->param.chunks_per_block;
        page = chunk_id % dev->param.chunks_per_block;

        if (!yaffs_check_chunk_bit(dev, block, page))
                yaffs_trace(YAFFS_TRACE_VERIFY,
                        "Deleting invalid chunk %d", chunk_id);

        bi = yaffs_get_block_info(dev, block);

        yaffs2_update_oldest_dirty_seq(dev, block, bi);

        yaffs_trace(YAFFS_TRACE_DELETION,
                "line %d delete of chunk %d",
                lyn, chunk_id);

        if (!dev->param.is_yaffs2 && mark_flash &&
            bi->block_state != YAFFS_BLOCK_STATE_COLLECTING) {

                memset(&tags, 0, sizeof(tags));
                tags.is_deleted = 1;
                yaffs_wr_chunk_tags_nand(dev, chunk_id, NULL, &tags);
                yaffs_handle_chunk_update(dev, chunk_id, &tags);
        } else {
                dev->n_unmarked_deletions++;
        }

        /* Pull out of the management area.
         * If the whole block became dirty, this will kick off an erasure.
         */
        if (bi->block_state == YAFFS_BLOCK_STATE_ALLOCATING ||
            bi->block_state == YAFFS_BLOCK_STATE_FULL ||
            bi->block_state == YAFFS_BLOCK_STATE_NEEDS_SCAN ||
            bi->block_state == YAFFS_BLOCK_STATE_COLLECTING) {
                dev->n_free_chunks++;
                yaffs_clear_chunk_bit(dev, block, page);
                bi->pages_in_use--;

                if (bi->pages_in_use == 0 &&
                    !bi->has_shrink_hdr &&
                    bi->block_state != YAFFS_BLOCK_STATE_ALLOCATING &&
                    bi->block_state != YAFFS_BLOCK_STATE_NEEDS_SCAN) {
                        yaffs_block_became_dirty(dev, block);
                }
        }
}

static int yaffs_wr_data_obj(struct yaffs_obj *in, int inode_chunk,
                             const u8 *buffer, int n_bytes, int use_reserve)
{
        /* Find old chunk Need to do this to get serial number
         * Write new one and patch into tree.
         * Invalidate old tags.
         */

        int prev_chunk_id;
        struct yaffs_ext_tags prev_tags;
        int new_chunk_id;
        struct yaffs_ext_tags new_tags;
        struct yaffs_dev *dev = in->my_dev;
        loff_t endpos;

        yaffs_check_gc(dev, 0);

        /* Get the previous chunk at this location in the file if it exists.
         * If it does not exist then put a zero into the tree. This creates
         * the tnode now, rather than later when it is harder to clean up.
         */
        prev_chunk_id = yaffs_find_chunk_in_file(in, inode_chunk, &prev_tags);
        if (prev_chunk_id < 1 &&
            !yaffs_put_chunk_in_file(in, inode_chunk, 0, 0))
                return 0;

        /* Set up new tags */
        memset(&new_tags, 0, sizeof(new_tags));

        new_tags.chunk_id = inode_chunk;
        new_tags.obj_id = in->obj_id;
        new_tags.serial_number =
            (prev_chunk_id > 0) ? prev_tags.serial_number + 1 : 1;
        new_tags.n_bytes = n_bytes;

        if (n_bytes < 1 || n_bytes > (int)dev->data_bytes_per_chunk) {
                yaffs_trace(YAFFS_TRACE_ERROR,
                  "Writing %d bytes to chunk!!!!!!!!!",
                   n_bytes);
                BUG();
        }

        /*
         * If this is a data chunk and the write goes past the end of the stored
         * size then update the stored_size.
         */
        if (inode_chunk > 0) {
                endpos =  (inode_chunk - 1) * dev->data_bytes_per_chunk +
                                n_bytes;
                if (in->variant.file_variant.stored_size < endpos)
                        in->variant.file_variant.stored_size = endpos;
        }

        new_chunk_id =
            yaffs_write_new_chunk(dev, buffer, &new_tags, use_reserve);

        if (new_chunk_id > 0) {
                yaffs_put_chunk_in_file(in, inode_chunk, new_chunk_id, 0);

                if (prev_chunk_id > 0)
                        yaffs_chunk_del(dev, prev_chunk_id, 1, __LINE__);

                yaffs_verify_file_sane(in);
        }
        return new_chunk_id;
}



static int yaffs_do_xattrib_mod(struct yaffs_obj *obj, int set,
                                const YCHAR *name, const void *value, int size,
                                int flags)
{
        struct yaffs_xattr_mod xmod;
        int result;

        xmod.set = set;
        xmod.name = name;
        xmod.data = value;
        xmod.size = size;
        xmod.flags = flags;
        xmod.result = -ENOSPC;

        result = yaffs_update_oh(obj, NULL, 0, 0, 0, &xmod);

        if (result > 0)
                return xmod.result;
        else
                return -ENOSPC;
}

static int yaffs_apply_xattrib_mod(struct yaffs_obj *obj, char *buffer,
                                   struct yaffs_xattr_mod *xmod)
{
        int retval = 0;
        int x_offs = sizeof(struct yaffs_obj_hdr);
        struct yaffs_dev *dev = obj->my_dev;
        int x_size = dev->data_bytes_per_chunk - sizeof(struct yaffs_obj_hdr);
        char *x_buffer = buffer + x_offs;

        if (xmod->set)
                retval =
                    nval_set(dev, x_buffer, x_size, xmod->name, xmod->data,
                             xmod->size, xmod->flags);
        else
                retval = nval_del(dev, x_buffer, x_size, xmod->name);

        obj->has_xattr = nval_hasvalues(dev, x_buffer, x_size);
        obj->xattr_known = 1;
        xmod->result = retval;

        return retval;
}

static int yaffs_do_xattrib_fetch(struct yaffs_obj *obj, const YCHAR *name,
                                  void *value, int size)
{
        char *buffer = NULL;
        int result;
        struct yaffs_ext_tags tags;
        struct yaffs_dev *dev = obj->my_dev;
        int x_offs = sizeof(struct yaffs_obj_hdr);
        int x_size = dev->data_bytes_per_chunk - sizeof(struct yaffs_obj_hdr);
        char *x_buffer;
        int retval = 0;

        if (obj->hdr_chunk < 1)
                return -ENODATA;

        /* If we know that the object has no xattribs then don't do all the
         * reading and parsing.
         */
        if (obj->xattr_known && !obj->has_xattr) {
                if (name)
                        return -ENODATA;
                else
                        return 0;
        }

        buffer = (char *)yaffs_get_temp_buffer(dev);
        if (!buffer)
                return -ENOMEM;

        result =
            yaffs_rd_chunk_tags_nand(dev, obj->hdr_chunk, (u8 *) buffer, &tags);

        if (result != YAFFS_OK)
                retval = -ENOENT;
        else {
                x_buffer = buffer + x_offs;

                if (!obj->xattr_known) {
                        obj->has_xattr = nval_hasvalues(dev, x_buffer, x_size);
                        obj->xattr_known = 1;
                }

                if (name)
                        retval = nval_get(dev, x_buffer, x_size,
                                                name, value, size);
                else
                        retval = nval_list(dev, x_buffer, x_size, value, size);
        }
        yaffs_release_temp_buffer(dev, (u8 *) buffer);
        return retval;
}

int yaffs_set_xattrib(struct yaffs_obj *obj, const YCHAR * name,
                      const void *value, int size, int flags)
{
        return yaffs_do_xattrib_mod(obj, 1, name, value, size, flags);
}

int yaffs_remove_xattrib(struct yaffs_obj *obj, const YCHAR * name)
{
        return yaffs_do_xattrib_mod(obj, 0, name, NULL, 0, 0);
}

int yaffs_get_xattrib(struct yaffs_obj *obj, const YCHAR * name, void *value,
                      int size)
{
        return yaffs_do_xattrib_fetch(obj, name, value, size);
}

int yaffs_list_xattrib(struct yaffs_obj *obj, char *buffer, int size)
{
        return yaffs_do_xattrib_fetch(obj, NULL, buffer, size);
}

static void yaffs_check_obj_details_loaded(struct yaffs_obj *in)
{
        u8 *buf;
        struct yaffs_obj_hdr *oh;
        struct yaffs_dev *dev;
        struct yaffs_ext_tags tags;
        int result;

        if (!in || !in->lazy_loaded || in->hdr_chunk < 1)
                return;

        dev = in->my_dev;
        buf = yaffs_get_temp_buffer(dev);

        result = yaffs_rd_chunk_tags_nand(dev, in->hdr_chunk, buf, &tags);

        if (result == YAFFS_FAIL)
                return;

        oh = (struct yaffs_obj_hdr *)buf;

        yaffs_do_endian_oh(dev, oh);

        in->lazy_loaded = 0;
        in->yst_mode = oh->yst_mode;
        yaffs_load_attribs(in, oh);
        yaffs_set_obj_name_from_oh(in, oh);

        if (in->variant_type == YAFFS_OBJECT_TYPE_SYMLINK)
                in->variant.symlink_variant.alias =
                    yaffs_clone_str(oh->alias);
        yaffs_release_temp_buffer(dev, buf);
}

/* UpdateObjectHeader updates the header on NAND for an object.
 * If name is not NULL, then that new name is used.
 *
 * We're always creating the obj header from scratch (except reading
 * the old name) so first set up in cpu endianness then run it through
 * endian fixing at the end.
 *
 * However, a twist: If there are xattribs we leave them as they were.
 *
 * Careful! The buffer holds the whole chunk. Part of the chunk holds the
 * object header and the rest holds the xattribs, therefore we use a buffer
 * pointer and an oh pointer to point to the same memory.
 */

int yaffs_update_oh(struct yaffs_obj *in, const YCHAR *name, int force,
                    int is_shrink, int shadows, struct yaffs_xattr_mod *xmod)
{

        struct yaffs_block_info *bi;
        struct yaffs_dev *dev = in->my_dev;
        int prev_chunk_id;
        int ret_val = 0;
        int result = 0;
        int new_chunk_id;
        struct yaffs_ext_tags new_tags;
        struct yaffs_ext_tags old_tags;
        const YCHAR *alias = NULL;
        u8 *buffer = NULL;
        YCHAR old_name[YAFFS_MAX_NAME_LENGTH + 1];
        struct yaffs_obj_hdr *oh = NULL;
        loff_t file_size = 0;

        strcpy(old_name, _Y("silly old name"));

        if (in->fake && in != dev->root_dir && !force && !xmod)
                return ret_val;

        yaffs_check_gc(dev, 0);
        yaffs_check_obj_details_loaded(in);

        buffer = yaffs_get_temp_buffer(in->my_dev);
        oh = (struct yaffs_obj_hdr *)buffer;

        prev_chunk_id = in->hdr_chunk;

        if (prev_chunk_id > 0) {
                /* Access the old obj header just to read the name. */
                result = yaffs_rd_chunk_tags_nand(dev, prev_chunk_id,
                                                  buffer, &old_tags);
                if (result == YAFFS_OK) {
                        yaffs_verify_oh(in, oh, &old_tags, 0);
                        memcpy(old_name, oh->name, sizeof(oh->name));

                        /*
                        * NB We only wipe the object header area because the rest of
                        * the buffer might contain xattribs.
                        */
                        memset(oh, 0xff, sizeof(*oh));
                }
        } else {
                memset(buffer, 0xff, dev->data_bytes_per_chunk);
        }

        oh->type = in->variant_type;
        oh->yst_mode = in->yst_mode;
        oh->shadows_obj = oh->inband_shadowed_obj_id = shadows;

        yaffs_load_attribs_oh(oh, in);

        if (in->parent)
                oh->parent_obj_id = in->parent->obj_id;
        else
                oh->parent_obj_id = 0;

        if (name && *name) {
                memset(oh->name, 0, sizeof(oh->name));
                yaffs_load_oh_from_name(dev, oh->name, name);
        } else if (prev_chunk_id > 0) {
                memcpy(oh->name, old_name, sizeof(oh->name));
        } else {
                memset(oh->name, 0, sizeof(oh->name));
        }

        oh->is_shrink = is_shrink;

        switch (in->variant_type) {
        case YAFFS_OBJECT_TYPE_UNKNOWN:
                /* Should not happen */
                break;
        case YAFFS_OBJECT_TYPE_FILE:
                if (oh->parent_obj_id != YAFFS_OBJECTID_DELETED &&
                    oh->parent_obj_id != YAFFS_OBJECTID_UNLINKED)
                        file_size = in->variant.file_variant.stored_size;
                yaffs_oh_size_load(dev, oh, file_size, 0);
                break;
        case YAFFS_OBJECT_TYPE_HARDLINK:
                oh->equiv_id = in->variant.hardlink_variant.equiv_id;
                break;
        case YAFFS_OBJECT_TYPE_SPECIAL:
                /* Do nothing */
                break;
        case YAFFS_OBJECT_TYPE_DIRECTORY:
                /* Do nothing */
                break;
        case YAFFS_OBJECT_TYPE_SYMLINK:
                alias = in->variant.symlink_variant.alias;
                if (!alias)
                        alias = _Y("no alias");
                strncpy(oh->alias, alias, YAFFS_MAX_ALIAS_LENGTH);
                oh->alias[YAFFS_MAX_ALIAS_LENGTH] = 0;
                break;
        }

        /* process any xattrib modifications */
        if (xmod)
                yaffs_apply_xattrib_mod(in, (char *)buffer, xmod);

        /* Tags */
        memset(&new_tags, 0, sizeof(new_tags));
        in->serial++;
        new_tags.chunk_id = 0;
        new_tags.obj_id = in->obj_id;
        new_tags.serial_number = in->serial;

        /* Add extra info for file header */
        new_tags.extra_available = 1;
        new_tags.extra_parent_id = oh->parent_obj_id;
        new_tags.extra_file_size = file_size;
        new_tags.extra_is_shrink = oh->is_shrink;
        new_tags.extra_equiv_id = oh->equiv_id;
        new_tags.extra_shadows = (oh->shadows_obj > 0) ? 1 : 0;
        new_tags.extra_obj_type = in->variant_type;

        /* Now endian swizzle the oh if needed. */
        yaffs_do_endian_oh(dev, oh);

        yaffs_verify_oh(in, oh, &new_tags, 1);

        /* Create new chunk in NAND */
        new_chunk_id =
            yaffs_write_new_chunk(dev, buffer, &new_tags,
                                  (prev_chunk_id > 0) ? 1 : 0);

        if (buffer)
                yaffs_release_temp_buffer(dev, buffer);

        if (new_chunk_id < 0)
                return new_chunk_id;

        in->hdr_chunk = new_chunk_id;

        if (prev_chunk_id > 0)
                yaffs_chunk_del(dev, prev_chunk_id, 1, __LINE__);

        if (!yaffs_obj_cache_dirty(in))
                in->dirty = 0;

        /* If this was a shrink, then mark the block
         * that the chunk lives on */
        if (is_shrink) {
                bi = yaffs_get_block_info(in->my_dev,
                                          new_chunk_id /
                                          in->my_dev->param.chunks_per_block);
                bi->has_shrink_hdr = 1;
        }


        return new_chunk_id;
}

/*--------------------- File read/write ------------------------
 * Read and write have very similar structures.
 * In general the read/write has three parts to it
 * An incomplete chunk to start with (if the read/write is not chunk-aligned)
 * Some complete chunks
 * An incomplete chunk to end off with
 *
 * Curve-balls: the first chunk might also be the last chunk.
 */

int yaffs_file_rd(struct yaffs_obj *in, u8 * buffer, loff_t offset, int n_bytes)
{
        int chunk;
        u32 start;
        int n_copy;
        int n = n_bytes;
        int n_done = 0;
        struct yaffs_cache *cache;
        struct yaffs_dev *dev;

        dev = in->my_dev;

        while (n > 0) {
                yaffs_addr_to_chunk(dev, offset, &chunk, &start);
                chunk++;

                /* OK now check for the curveball where the start and end are in
                 * the same chunk.
                 */
                if ((start + n) < dev->data_bytes_per_chunk)
                        n_copy = n;
                else
                        n_copy = dev->data_bytes_per_chunk - start;

                cache = yaffs_find_chunk_cache(in, chunk);

                /* If the chunk is already in the cache or it is less than
                 * a whole chunk or we're using inband tags then use the cache
                 * (if there is caching) else bypass the cache.
                 */
                if (cache || n_copy != (int)dev->data_bytes_per_chunk ||
                    dev->param.inband_tags) {
                        if (dev->param.n_caches > 0) {

                                /* If we can't find the data in the cache,
                                 * then load it up. */

                                if (!cache) {
                                        cache =
                                            yaffs_grab_chunk_cache(in->my_dev);
                                        cache->object = in;
                                        cache->chunk_id = chunk;
                                        cache->dirty = 0;
                                        cache->locked = 0;
                                        yaffs_rd_data_obj(in, chunk,
                                                          cache->data);
                                        cache->n_bytes = 0;
                                }

                                yaffs_use_cache(dev, cache, 0);

                                cache->locked = 1;

                                memcpy(buffer, &cache->data[start], n_copy);

                                cache->locked = 0;
                        } else {
                                /* Read into the local buffer then copy.. */

                                u8 *local_buffer =
                                    yaffs_get_temp_buffer(dev);
                                yaffs_rd_data_obj(in, chunk, local_buffer);

                                memcpy(buffer, &local_buffer[start], n_copy);

                                yaffs_release_temp_buffer(dev, local_buffer);
                        }
                } else {
                        /* A full chunk. Read directly into the buffer. */
                        yaffs_rd_data_obj(in, chunk, buffer);
                }
                n -= n_copy;
                offset += n_copy;
                buffer += n_copy;
                n_done += n_copy;
        }
        return n_done;
}

int yaffs_do_file_wr(struct yaffs_obj *in, const u8 *buffer, loff_t offset,
                     int n_bytes, int write_through)
{

        int chunk;
        u32 start;
        int n_copy;
        int n = n_bytes;
        int n_done = 0;
        int n_writeback;
        loff_t start_write = offset;
        int chunk_written = 0;
        u32 n_bytes_read;
        loff_t chunk_start;
        struct yaffs_dev *dev;

        dev = in->my_dev;

        while (n > 0 && chunk_written >= 0) {
                yaffs_addr_to_chunk(dev, offset, &chunk, &start);

                if (((loff_t)chunk) *
                    dev->data_bytes_per_chunk + start != offset ||
                    start >= dev->data_bytes_per_chunk) {
                        yaffs_trace(YAFFS_TRACE_ERROR,
                                "AddrToChunk of offset %lld gives chunk %d start %d",
                                (long  long)offset, chunk, start);
                }
                chunk++;        /* File pos to chunk in file offset */

                /* OK now check for the curveball where the start and end are in
                 * the same chunk.
                 */

                if ((start + n) < dev->data_bytes_per_chunk) {
                        n_copy = n;

                        /* Now calculate how many bytes to write back....
                         * If we're overwriting and not writing to then end of
                         * file then we need to write back as much as was there
                         * before.
                         */

                        chunk_start = (((loff_t)(chunk - 1)) *
                                        dev->data_bytes_per_chunk);

                        if (chunk_start > in->variant.file_variant.file_size)
                                n_bytes_read = 0;       /* Past end of file */
                        else
                                n_bytes_read =
                                    in->variant.file_variant.file_size -
                                    chunk_start;

                        if (n_bytes_read > dev->data_bytes_per_chunk)
                                n_bytes_read = dev->data_bytes_per_chunk;

                        n_writeback =
                            (n_bytes_read >
                             (start + n)) ? n_bytes_read : (start + n);

                        if (n_writeback < 0 ||
                            n_writeback > (int)dev->data_bytes_per_chunk)
                                BUG();

                } else {
                        n_copy = dev->data_bytes_per_chunk - start;
                        n_writeback = dev->data_bytes_per_chunk;
                }

                if (n_copy != (int)dev->data_bytes_per_chunk ||
                    !dev->param.cache_bypass_aligned ||
                    dev->param.inband_tags) {
                        /* An incomplete start or end chunk (or maybe both
                         * start and end chunk), or we're using inband tags,
                         * or we're forcing writes through the cache,
                         * so we want to use the cache buffers.
                         */
                        if (dev->param.n_caches > 0) {
                                struct yaffs_cache *cache;

                                /* If we can't find the data in the cache, then
                                 * load the cache */
                                cache = yaffs_find_chunk_cache(in, chunk);

                                if (!cache &&
                                    yaffs_check_alloc_available(dev, 1)) {
                                        cache = yaffs_grab_chunk_cache(dev);
                                        cache->object = in;
                                        cache->chunk_id = chunk;
                                        cache->dirty = 0;
                                        cache->locked = 0;
                                        yaffs_rd_data_obj(in, chunk,
                                                          cache->data);
                                } else if (cache &&
                                           !cache->dirty &&
                                           !yaffs_check_alloc_available(dev,
                                                                        1)) {
                                        /* Drop the cache if it was a read cache
                                         * item and no space check has been made
                                         * for it.
                                         */
                                        cache = NULL;
                                }

                                if (cache) {
                                        yaffs_use_cache(dev, cache, 1);
                                        cache->locked = 1;

                                        memcpy(&cache->data[start], buffer,
                                               n_copy);

                                        cache->locked = 0;
                                        cache->n_bytes = n_writeback;

                                        if (write_through) {
                                                chunk_written =
                                                    yaffs_wr_data_obj
                                                    (cache->object,
                                                     cache->chunk_id,
                                                     cache->data,
                                                     cache->n_bytes, 1);
                                                cache->dirty = 0;
                                        }
                                } else {
                                        chunk_written = -1;     /* fail write */
                                }
                        } else {
                                /* An incomplete start or end chunk (or maybe
                                 * both start and end chunk). Read into the
                                 * local buffer then copy over and write back.
                                 */

                                u8 *local_buffer = yaffs_get_temp_buffer(dev);

                                yaffs_rd_data_obj(in, chunk, local_buffer);
                                memcpy(&local_buffer[start], buffer, n_copy);

                                chunk_written =
                                    yaffs_wr_data_obj(in, chunk,
                                                      local_buffer,
                                                      n_writeback, 0);

                                yaffs_release_temp_buffer(dev, local_buffer);
                        }
                } else {
                        /* A full chunk. Write directly from the buffer. */

                        chunk_written =
                            yaffs_wr_data_obj(in, chunk, buffer,
                                              dev->data_bytes_per_chunk, 0);

                        /* Since we've overwritten the cached data,
                         * we better invalidate it. */
                        yaffs_invalidate_chunk_cache(in, chunk);
                }

                if (chunk_written >= 0) {
                        n -= n_copy;
                        offset += n_copy;
                        buffer += n_copy;
                        n_done += n_copy;
                }
        }

        /* Update file object */

        if ((start_write + n_done) > in->variant.file_variant.file_size)
                in->variant.file_variant.file_size = (start_write + n_done);

        in->dirty = 1;
        return n_done;
}

int yaffs_wr_file(struct yaffs_obj *in, const u8 *buffer, loff_t offset,
                  int n_bytes, int write_through)
{
        yaffs2_handle_hole(in, offset);
        return yaffs_do_file_wr(in, buffer, offset, n_bytes, write_through);
}

/* ---------------------- File resizing stuff ------------------ */

static void yaffs_prune_chunks(struct yaffs_obj *in, loff_t new_size)
{

        struct yaffs_dev *dev = in->my_dev;
        loff_t old_size = in->variant.file_variant.file_size;
        int i;
        int chunk_id;
        u32 dummy;
        int last_del;
        int start_del;

        if (old_size > 0)
                yaffs_addr_to_chunk(dev, old_size - 1, &last_del, &dummy);
        else
                last_del = 0;

        yaffs_addr_to_chunk(dev, new_size + dev->data_bytes_per_chunk - 1,
                                &start_del, &dummy);
        last_del++;
        start_del++;

        /* Delete backwards so that we don't end up with holes if
         * power is lost part-way through the operation.
         */
        for (i = last_del; i >= start_del; i--) {
                /* NB this could be optimised somewhat,
                 * eg. could retrieve the tags and write them without
                 * using yaffs_chunk_del
                 */

                chunk_id = yaffs_find_del_file_chunk(in, i, NULL);

                if (chunk_id < 1)
                        continue;

                if ((u32)chunk_id <
                    (dev->internal_start_block * dev->param.chunks_per_block) ||
                    (u32)chunk_id >=
                    ((dev->internal_end_block + 1) *
                      dev->param.chunks_per_block)) {
                        yaffs_trace(YAFFS_TRACE_ALWAYS,
                                "Found daft chunk_id %d for %d",
                                chunk_id, i);
                } else {
                        in->n_data_chunks--;
                        yaffs_chunk_del(dev, chunk_id, 1, __LINE__);
                }
        }
}

void yaffs_resize_file_down(struct yaffs_obj *obj, loff_t new_size)
{
        int new_full;
        u32 new_partial;
        struct yaffs_dev *dev = obj->my_dev;

        yaffs_addr_to_chunk(dev, new_size, &new_full, &new_partial);

        yaffs_prune_chunks(obj, new_size);

        if (new_partial != 0) {
                int last_chunk = 1 + new_full;
                u8 *local_buffer = yaffs_get_temp_buffer(dev);

                /* Rewrite the last chunk with its new size and zero pad */
                yaffs_rd_data_obj(obj, last_chunk, local_buffer);
                memset(local_buffer + new_partial, 0,
                       dev->data_bytes_per_chunk - new_partial);

                yaffs_wr_data_obj(obj, last_chunk, local_buffer,
                                  new_partial, 1);

                yaffs_release_temp_buffer(dev, local_buffer);
        }

        obj->variant.file_variant.file_size = new_size;
        obj->variant.file_variant.stored_size = new_size;

        yaffs_prune_tree(dev, &obj->variant.file_variant);
}

int yaffs_resize_file(struct yaffs_obj *in, loff_t new_size)
{
        struct yaffs_dev *dev = in->my_dev;
        loff_t old_size = in->variant.file_variant.file_size;

        yaffs_flush_file_cache(in, 1);
        yaffs_invalidate_whole_cache(in);

        yaffs_check_gc(dev, 0);

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

        if (new_size == old_size)
                return YAFFS_OK;

        if (new_size > old_size) {
                yaffs2_handle_hole(in, new_size);
                in->variant.file_variant.file_size = new_size;
        } else {
                /* new_size < old_size */
                yaffs_resize_file_down(in, new_size);
        }

        /* Write a new object header to reflect the resize.
         * show we've shrunk the file, if need be
         * Do this only if the file is not in the deleted directories
         * and is not shadowed.
         */
        if (in->parent &&
            !in->is_shadowed &&
            in->parent->obj_id != YAFFS_OBJECTID_UNLINKED &&
            in->parent->obj_id != YAFFS_OBJECTID_DELETED)
                yaffs_update_oh(in, NULL, 0, 0, 0, NULL);

        return YAFFS_OK;
}

int yaffs_flush_file(struct yaffs_obj *in,
                     int update_time,
                     int data_sync,
                     int discard_cache)
{
        if (!in->dirty)
                return YAFFS_OK;

        yaffs_flush_file_cache(in, discard_cache);

        if (data_sync)
                return YAFFS_OK;

        if (update_time)
                yaffs_load_current_time(in, 0, 0);

        return (yaffs_update_oh(in, NULL, 0, 0, 0, NULL) >= 0) ?
                                YAFFS_OK : YAFFS_FAIL;
}


/* yaffs_del_file deletes the whole file data
 * and the inode associated with the file.
 * It does not delete the links associated with the file.
 */
static int yaffs_unlink_file_if_needed(struct yaffs_obj *in)
{
        int ret_val;
        int del_now = 0;
        struct yaffs_dev *dev = in->my_dev;

        if (!in->my_inode)
                del_now = 1;

        if (del_now) {
                ret_val =
                    yaffs_change_obj_name(in, in->my_dev->del_dir,
                                          _Y("deleted"), 0, 0);
                yaffs_trace(YAFFS_TRACE_TRACING,
                        "yaffs: immediate deletion of file %d",
                        in->obj_id);
                in->deleted = 1;
                in->my_dev->n_deleted_files++;
                if (dev->param.disable_soft_del || dev->param.is_yaffs2)
                        yaffs_resize_file(in, 0);
                yaffs_soft_del_file(in);
        } else {
                ret_val =
                    yaffs_change_obj_name(in, in->my_dev->unlinked_dir,
                                          _Y("unlinked"), 0, 0);
        }
        return ret_val;
}

static int yaffs_del_file(struct yaffs_obj *in)
{
        int ret_val = YAFFS_OK;
        int deleted;    /* Need to cache value on stack if in is freed */
        struct yaffs_dev *dev = in->my_dev;

        if (dev->param.disable_soft_del || dev->param.is_yaffs2)
                yaffs_resize_file(in, 0);

        if (in->n_data_chunks > 0) {
                /* Use soft deletion if there is data in the file.
                 * That won't be the case if it has been resized to zero.
                 */
                if (!in->unlinked)
                        ret_val = yaffs_unlink_file_if_needed(in);

                deleted = in->deleted;

                if (ret_val == YAFFS_OK && in->unlinked && !in->deleted) {
                        in->deleted = 1;
                        deleted = 1;
                        in->my_dev->n_deleted_files++;
                        yaffs_soft_del_file(in);
                }
                return deleted ? YAFFS_OK : YAFFS_FAIL;
        } else {
                /* The file has no data chunks so we toss it immediately */
                yaffs_free_tnode(in->my_dev, in->variant.file_variant.top);
                in->variant.file_variant.top = NULL;
                yaffs_generic_obj_del(in);

                return YAFFS_OK;
        }
}

int yaffs_is_non_empty_dir(struct yaffs_obj *obj)
{
        return (obj &&
                obj->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY) &&
                !(list_empty(&obj->variant.dir_variant.children));
}

static int yaffs_del_dir(struct yaffs_obj *obj)
{
        /* First check that the directory is empty. */
        if (yaffs_is_non_empty_dir(obj))
                return YAFFS_FAIL;

        return yaffs_generic_obj_del(obj);
}

static int yaffs_del_symlink(struct yaffs_obj *in)
{
        kfree(in->variant.symlink_variant.alias);
        in->variant.symlink_variant.alias = NULL;

        return yaffs_generic_obj_del(in);
}

static int yaffs_del_link(struct yaffs_obj *in)
{
        /* remove this hardlink from the list associated with the equivalent
         * object
         */
        list_del_init(&in->hard_links);
        return yaffs_generic_obj_del(in);
}

int yaffs_del_obj(struct yaffs_obj *obj)
{
        int ret_val = -1;

        switch (obj->variant_type) {
        case YAFFS_OBJECT_TYPE_FILE:
                ret_val = yaffs_del_file(obj);
                break;
        case YAFFS_OBJECT_TYPE_DIRECTORY:
                if (!list_empty(&obj->variant.dir_variant.dirty)) {
                        yaffs_trace(YAFFS_TRACE_BACKGROUND,
                                "Remove object %d from dirty directories",
                                obj->obj_id);
                        list_del_init(&obj->variant.dir_variant.dirty);
                }
                return yaffs_del_dir(obj);
                break;
        case YAFFS_OBJECT_TYPE_SYMLINK:
                ret_val = yaffs_del_symlink(obj);
                break;
        case YAFFS_OBJECT_TYPE_HARDLINK:
                ret_val = yaffs_del_link(obj);
                break;
        case YAFFS_OBJECT_TYPE_SPECIAL:
                ret_val = yaffs_generic_obj_del(obj);
                break;
        case YAFFS_OBJECT_TYPE_UNKNOWN:
                ret_val = 0;
                break;          /* should not happen. */
        }
        return ret_val;
}


static void yaffs_empty_dir_to_dir(struct yaffs_obj *from_dir,
                                   struct yaffs_obj *to_dir)
{
        struct yaffs_obj *obj;
        struct list_head *lh;
        struct list_head *n;

        list_for_each_safe(lh, n, &from_dir->variant.dir_variant.children) {
                obj = list_entry(lh, struct yaffs_obj, siblings);
                yaffs_add_obj_to_dir(to_dir, obj);
        }
}

struct yaffs_obj *yaffs_retype_obj(struct yaffs_obj *obj,
                                   enum yaffs_obj_type type)
{
        /* Tear down the old variant */
        switch (obj->variant_type) {
        case YAFFS_OBJECT_TYPE_FILE:
                /* Nuke file data */
                yaffs_resize_file(obj, 0);
                yaffs_free_tnode(obj->my_dev, obj->variant.file_variant.top);
                obj->variant.file_variant.top = NULL;
                break;
        case YAFFS_OBJECT_TYPE_DIRECTORY:
                /* Put the children in lost and found. */
                yaffs_empty_dir_to_dir(obj, obj->my_dev->lost_n_found);
                if (!list_empty(&obj->variant.dir_variant.dirty))
                        list_del_init(&obj->variant.dir_variant.dirty);
                break;
        case YAFFS_OBJECT_TYPE_SYMLINK:
                /* Nuke symplink data */
                kfree(obj->variant.symlink_variant.alias);
                obj->variant.symlink_variant.alias = NULL;
                break;
        case YAFFS_OBJECT_TYPE_HARDLINK:
                list_del_init(&obj->hard_links);
                break;
        default:
                break;
        }

        memset(&obj->variant, 0, sizeof(obj->variant));

        /*Set up new variant if the memset is not enough. */
        switch (type) {
        case YAFFS_OBJECT_TYPE_DIRECTORY:
                INIT_LIST_HEAD(&obj->variant.dir_variant.children);
                INIT_LIST_HEAD(&obj->variant.dir_variant.dirty);
                break;
        case YAFFS_OBJECT_TYPE_FILE:
        case YAFFS_OBJECT_TYPE_SYMLINK:
        case YAFFS_OBJECT_TYPE_HARDLINK:
        default:
                break;
        }

        obj->variant_type = type;

        return obj;

}

static int yaffs_unlink_worker(struct yaffs_obj *obj)
{
        int del_now = 0;

        if (!obj)
                return YAFFS_FAIL;

        if (!obj->my_inode)
                del_now = 1;

        yaffs_update_parent(obj->parent);

        if (obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK) {
                return yaffs_del_link(obj);
        } else if (!list_empty(&obj->hard_links)) {
                /* Curve ball: We're unlinking an object that has a hardlink.
                 *
                 * This problem arises because we are not strictly following
                 * The Linux link/inode model.
                 *
                 * We can't really delete the object.
                 * Instead, we do the following:
                 * - Select a hardlink.
                 * - Unhook it from the hard links
                 * - Move it from its parent directory so that the rename works.
                 * - Rename the object to the hardlink's name.
                 * - Delete the hardlink
                 */

                struct yaffs_obj *hl;
                struct yaffs_obj *parent;
                int ret_val;
                YCHAR name[YAFFS_MAX_NAME_LENGTH + 1];

                hl = list_entry(obj->hard_links.next, struct yaffs_obj,
                                hard_links);

                yaffs_get_obj_name(hl, name, YAFFS_MAX_NAME_LENGTH + 1);
                parent = hl->parent;

                list_del_init(&hl->hard_links);

                yaffs_add_obj_to_dir(obj->my_dev->unlinked_dir, hl);

                ret_val = yaffs_change_obj_name(obj, parent, name, 0, 0);

                if (ret_val == YAFFS_OK)
                        ret_val = yaffs_generic_obj_del(hl);

                return ret_val;

        } else if (del_now) {
                switch (obj->variant_type) {
                case YAFFS_OBJECT_TYPE_FILE:
                        return yaffs_del_file(obj);
                        break;
                case YAFFS_OBJECT_TYPE_DIRECTORY:
                        list_del_init(&obj->variant.dir_variant.dirty);
                        return yaffs_del_dir(obj);
                        break;
                case YAFFS_OBJECT_TYPE_SYMLINK:
                        return yaffs_del_symlink(obj);
                        break;
                case YAFFS_OBJECT_TYPE_SPECIAL:
                        return yaffs_generic_obj_del(obj);
                        break;
                case YAFFS_OBJECT_TYPE_HARDLINK:
                case YAFFS_OBJECT_TYPE_UNKNOWN:
                default:
                        return YAFFS_FAIL;
                }
        } else if (yaffs_is_non_empty_dir(obj)) {
                return YAFFS_FAIL;
        } else {
                return yaffs_change_obj_name(obj, obj->my_dev->unlinked_dir,
                                                _Y("unlinked"), 0, 0);
        }
}

int yaffs_unlink_obj(struct yaffs_obj *obj)
{
        if (obj && obj->unlink_allowed)
                return yaffs_unlink_worker(obj);

        return YAFFS_FAIL;
}

int yaffs_unlinker(struct yaffs_obj *dir, const YCHAR *name)
{
        struct yaffs_obj *obj;

        obj = yaffs_find_by_name(dir, name);
        return yaffs_unlink_obj(obj);
}

/* Note:
 * If old_name is NULL then we take old_dir as the object to be renamed.
 */
int yaffs_rename_obj(struct yaffs_obj *old_dir, const YCHAR *old_name,
                     struct yaffs_obj *new_dir, const YCHAR *new_name)
{
        struct yaffs_obj *obj = NULL;
        struct yaffs_obj *existing_target = NULL;
        int force = 0;
        int result;
        struct yaffs_dev *dev;

        if (!old_dir || old_dir->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
                BUG();
                return YAFFS_FAIL;
        }
        if (!new_dir || new_dir->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
                BUG();
                return YAFFS_FAIL;
        }

        dev = old_dir->my_dev;

#ifdef CONFIG_YAFFS_CASE_INSENSITIVE
        /* Special case for case insemsitive systems.
         * While look-up is case insensitive, the name isn't.
         * Therefore we might want to change x.txt to X.txt
         */
        if (old_dir == new_dir &&
                old_name && new_name &&
                strcmp(old_name, new_name) == 0)
                force = 1;
#endif

        if (strnlen(new_name, YAFFS_MAX_NAME_LENGTH + 1) >
            YAFFS_MAX_NAME_LENGTH)
                /* ENAMETOOLONG */
                return YAFFS_FAIL;

        if (old_name)
                obj = yaffs_find_by_name(old_dir, old_name);
        else{
                obj = old_dir;
                old_dir = obj->parent;
        }

        if (obj && obj->rename_allowed) {
                /* Now handle an existing target, if there is one */
                existing_target = yaffs_find_by_name(new_dir, new_name);
                if (yaffs_is_non_empty_dir(existing_target)) {
                        return YAFFS_FAIL;      /* ENOTEMPTY */
                } else if (existing_target && existing_target != obj) {
                        /* Nuke the target first, using shadowing,
                         * but only if it isn't the same object.
                         *
                         * Note we must disable gc here otherwise it can mess
                         * up the shadowing.
                         *
                         */
                        dev->gc_disable = 1;
                        yaffs_change_obj_name(obj, new_dir, new_name, force,
                                              existing_target->obj_id);
                        existing_target->is_shadowed = 1;
                        yaffs_unlink_obj(existing_target);
                        dev->gc_disable = 0;
                }

                result = yaffs_change_obj_name(obj, new_dir, new_name, 1, 0);

                yaffs_update_parent(old_dir);
                if (new_dir != old_dir)
                        yaffs_update_parent(new_dir);

                return result;
        }
        return YAFFS_FAIL;
}

/*----------------------- Initialisation Scanning ---------------------- */

void yaffs_handle_shadowed_obj(struct yaffs_dev *dev, int obj_id,
                               int backward_scanning)
{
        struct yaffs_obj *obj;

        if (backward_scanning) {
                /* Handle YAFFS2 case (backward scanning)
                 * If the shadowed object exists then ignore.
                 */
                obj = yaffs_find_by_number(dev, obj_id);
                if (obj)
                        return;
        }

        /* Let's create it (if it does not exist) assuming it is a file so that
         * it can do shrinking etc.
         * We put it in unlinked dir to be cleaned up after the scanning
         */
        obj =
            yaffs_find_or_create_by_number(dev, obj_id, YAFFS_OBJECT_TYPE_FILE);
        if (!obj)
                return;
        obj->is_shadowed = 1;
        yaffs_add_obj_to_dir(dev->unlinked_dir, obj);
        obj->variant.file_variant.shrink_size = 0;
        obj->valid = 1;         /* So that we don't read any other info. */
}

void yaffs_link_fixup(struct yaffs_dev *dev, struct list_head *hard_list)
{
        struct list_head *lh;
        struct list_head *save;
        struct yaffs_obj *hl;
        struct yaffs_obj *in;

        list_for_each_safe(lh, save, hard_list) {
                hl = list_entry(lh, struct yaffs_obj, hard_links);
                in = yaffs_find_by_number(dev,
                                        hl->variant.hardlink_variant.equiv_id);

                if (in) {
                        /* Add the hardlink pointers */
                        hl->variant.hardlink_variant.equiv_obj = in;
                        list_add(&hl->hard_links, &in->hard_links);
                } else {
                        /* Todo Need to report/handle this better.
                         * Got a problem... hardlink to a non-existant object
                         */
                        hl->variant.hardlink_variant.equiv_obj = NULL;
                        INIT_LIST_HEAD(&hl->hard_links);
                }
        }
}

static void yaffs_strip_deleted_objs(struct yaffs_dev *dev)
{
        /*
         *  Sort out state of unlinked and deleted objects after scanning.
         */
        struct list_head *i;
        struct list_head *n;
        struct yaffs_obj *l;

        if (dev->read_only)
                return;

        /* Soft delete all the unlinked files */
        list_for_each_safe(i, n,
                           &dev->unlinked_dir->variant.dir_variant.children) {
                l = list_entry(i, struct yaffs_obj, siblings);
                yaffs_del_obj(l);
        }

        list_for_each_safe(i, n, &dev->del_dir->variant.dir_variant.children) {
                l = list_entry(i, struct yaffs_obj, siblings);
                yaffs_del_obj(l);
        }
}

/*
 * This code iterates through all the objects making sure that they are rooted.
 * Any unrooted objects are re-rooted in lost+found.
 * An object needs to be in one of:
 * - Directly under deleted, unlinked
 * - Directly or indirectly under root.
 *
 * Note:
 *  This code assumes that we don't ever change the current relationships
 *  between directories:
 *   root_dir->parent == unlinked_dir->parent == del_dir->parent == NULL
 *   lost-n-found->parent == root_dir
 *
 * This fixes the problem where directories might have inadvertently been
 * deleted leaving the object "hanging" without being rooted in the
 * directory tree.
 */

static int yaffs_has_null_parent(struct yaffs_dev *dev, struct yaffs_obj *obj)
{
        return (obj == dev->del_dir ||
                obj == dev->unlinked_dir || obj == dev->root_dir);
}

static void yaffs_fix_hanging_objs(struct yaffs_dev *dev)
{
        struct yaffs_obj *obj;
        struct yaffs_obj *parent;
        int i;
        struct list_head *lh;
        struct list_head *n;
        int depth_limit;
        int hanging;

        if (dev->read_only)
                return;

        /* Iterate through the objects in each hash entry,
         * looking at each object.
         * Make sure it is rooted.
         */

        for (i = 0; i < YAFFS_NOBJECT_BUCKETS; i++) {
                list_for_each_safe(lh, n, &dev->obj_bucket[i].list) {
                        obj = list_entry(lh, struct yaffs_obj, hash_link);
                        parent = obj->parent;

                        if (yaffs_has_null_parent(dev, obj)) {
                                /* These directories are not hanging */
                                hanging = 0;
                        } else if (!parent ||
                                   parent->variant_type !=
                                   YAFFS_OBJECT_TYPE_DIRECTORY) {
                                hanging = 1;
                        } else if (yaffs_has_null_parent(dev, parent)) {
                                hanging = 0;
                        } else {
                                /*
                                 * Need to follow the parent chain to
                                 * see if it is hanging.
                                 */
                                hanging = 0;
                                depth_limit = 100;

                                while (parent != dev->root_dir &&
                                       parent->parent &&
                                       parent->parent->variant_type ==
                                       YAFFS_OBJECT_TYPE_DIRECTORY &&
                                       depth_limit > 0) {
                                        parent = parent->parent;
                                        depth_limit--;
                                }
                                if (parent != dev->root_dir)
                                        hanging = 1;
                        }
                        if (hanging) {
                                yaffs_trace(YAFFS_TRACE_SCAN,
                                        "Hanging object %d moved to lost and found",
                                        obj->obj_id);
                                yaffs_add_obj_to_dir(dev->lost_n_found, obj);
                        }
                }
        }
}

/*
 * Delete directory contents for cleaning up lost and found.
 */
static void yaffs_del_dir_contents(struct yaffs_obj *dir)
{
        struct yaffs_obj *obj;
        struct list_head *lh;
        struct list_head *n;

        if (dir->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY)
                BUG();

        list_for_each_safe(lh, n, &dir->variant.dir_variant.children) {
                obj = list_entry(lh, struct yaffs_obj, siblings);
                if (obj->variant_type == YAFFS_OBJECT_TYPE_DIRECTORY)
                        yaffs_del_dir_contents(obj);
                yaffs_trace(YAFFS_TRACE_SCAN,
                        "Deleting lost_found object %d",
                        obj->obj_id);
                yaffs_unlink_obj(obj);
        }
}

static void yaffs_empty_l_n_f(struct yaffs_dev *dev)
{
        yaffs_del_dir_contents(dev->lost_n_found);
}


struct yaffs_obj *yaffs_find_by_name(struct yaffs_obj *directory,
                                     const YCHAR *name)
{
        int sum;
        struct list_head *i;
        YCHAR buffer[YAFFS_MAX_NAME_LENGTH + 1];
        struct yaffs_obj *l;

        if (!name)
                return NULL;

        if (!directory) {
                yaffs_trace(YAFFS_TRACE_ALWAYS,
                        "tragedy: yaffs_find_by_name: null pointer directory"
                        );
                BUG();
                return NULL;
        }
        if (directory->variant_type != YAFFS_OBJECT_TYPE_DIRECTORY) {
                yaffs_trace(YAFFS_TRACE_ALWAYS,
                        "tragedy: yaffs_find_by_name: non-directory"
                        );
                BUG();
        }

        sum = yaffs_calc_name_sum(name);

        list_for_each(i, &directory->variant.dir_variant.children) {
                l = list_entry(i, struct yaffs_obj, siblings);

                if (l->parent != directory)
                        BUG();

                yaffs_check_obj_details_loaded(l);

                /* Special case for lost-n-found */
                if (l->obj_id == YAFFS_OBJECTID_LOSTNFOUND) {
                        if (!strcmp(name, YAFFS_LOSTNFOUND_NAME))
                                return l;
                } else if (l->sum == sum || l->hdr_chunk <= 0) {
                        /* LostnFound chunk called Objxxx
                         * Do a real check
                         */
                        yaffs_get_obj_name(l, buffer,
                                YAFFS_MAX_NAME_LENGTH + 1);
                        if (!strncmp(name, buffer, YAFFS_MAX_NAME_LENGTH))
                                return l;
                }
        }
        return NULL;
}

/* GetEquivalentObject dereferences any hard links to get to the
 * actual object.
 */

struct yaffs_obj *yaffs_get_equivalent_obj(struct yaffs_obj *obj)
{
        if (obj && obj->variant_type == YAFFS_OBJECT_TYPE_HARDLINK) {
                obj = obj->variant.hardlink_variant.equiv_obj;
                yaffs_check_obj_details_loaded(obj);
        }
        return obj;
}

/*
 *  A note or two on object names.
 *  * If the object name is missing, we then make one up in the form objnnn
 *
 *  * ASCII names are stored in the object header's name field from byte zero
 *  * Unicode names are historically stored starting from byte zero.
 *
 * Then there are automatic Unicode names...
 * The purpose of these is to save names in a way that can be read as
 * ASCII or Unicode names as appropriate, thus allowing a Unicode and ASCII
 * system to share files.
 *
 * These automatic unicode are stored slightly differently...
 *  - If the name can fit in the ASCII character space then they are saved as
 *    ascii names as per above.
 *  - If the name needs Unicode then the name is saved in Unicode
 *    starting at oh->name[1].

 */
static void yaffs_fix_null_name(struct yaffs_obj *obj, YCHAR *name,
                                int buffer_size)
{
        /* Create an object name if we could not find one. */
        if (strnlen(name, YAFFS_MAX_NAME_LENGTH) == 0) {
                YCHAR local_name[20];
                YCHAR num_string[20];
                YCHAR *x = &num_string[19];
                unsigned v = obj->obj_id;
                num_string[19] = 0;
                while (v > 0) {
                        x--;
                        *x = '0' + (v % 10);
                        v /= 10;
                }
                /* make up a name */
                strcpy(local_name, YAFFS_LOSTNFOUND_PREFIX);
                strcat(local_name, x);
                strncpy(name, local_name, buffer_size - 1);
        }
}

int yaffs_get_obj_name(struct yaffs_obj *obj, YCHAR *name, int buffer_size)
{
        memset(name, 0, buffer_size * sizeof(YCHAR));
        yaffs_check_obj_details_loaded(obj);
        if (obj->obj_id == YAFFS_OBJECTID_LOSTNFOUND) {
                strncpy(name, YAFFS_LOSTNFOUND_NAME, buffer_size - 1);
        } else if (obj->short_name[0]) {
                strcpy(name, obj->short_name);
        } else if (obj->hdr_chunk > 0) {
                int result;
                u8 *buffer = yaffs_get_temp_buffer(obj->my_dev);

                struct yaffs_obj_hdr *oh = (struct yaffs_obj_hdr *)buffer;

                memset(buffer, 0, obj->my_dev->data_bytes_per_chunk);

                if (obj->hdr_chunk > 0) {
                        result = yaffs_rd_chunk_tags_nand(obj->my_dev,
                                obj->hdr_chunk, buffer, NULL);
                        if (result == YAFFS_OK)
                                yaffs_load_name_from_oh(obj->my_dev, name,
                                        oh->name, buffer_size);
                }
                yaffs_release_temp_buffer(obj->my_dev, buffer);
        }

        yaffs_fix_null_name(obj, name, buffer_size);

        return strnlen(name, YAFFS_MAX_NAME_LENGTH);
}

loff_t yaffs_get_obj_length(struct yaffs_obj *obj)
{
        /* Dereference any hard linking */
        obj = yaffs_get_equivalent_obj(obj);

        if (obj->variant_type == YAFFS_OBJECT_TYPE_FILE)
                return obj->variant.file_variant.file_size;
        if (obj->variant_type == YAFFS_OBJECT_TYPE_SYMLINK) {
                if (!obj->variant.symlink_variant.alias)
                        return 0;
                return strnlen(obj->variant.symlink_variant.alias,
                                     YAFFS_MAX_ALIAS_LENGTH);
        } else {
                /* Only a directory should drop through to here */
                return obj->my_dev->data_bytes_per_chunk;
        }
}

int yaffs_get_obj_link_count(struct yaffs_obj *obj)
{
        int count = 0;
        struct list_head *i;

        if (!obj->unlinked)
                count++;        /* the object itself */

        list_for_each(i, &obj->hard_links)
            count++;            /* add the hard links; */

        return count;
}

int yaffs_get_obj_inode(struct yaffs_obj *obj)
{
        obj = yaffs_get_equivalent_obj(obj);

        return obj->obj_id;
}

unsigned yaffs_get_obj_type(struct yaffs_obj *obj)
{
        obj = yaffs_get_equivalent_obj(obj);

        switch (obj->variant_type) {
        case YAFFS_OBJECT_TYPE_FILE:
                return DT_REG;
                break;
        case YAFFS_OBJECT_TYPE_DIRECTORY:
                return DT_DIR;
                break;
        case YAFFS_OBJECT_TYPE_SYMLINK:
                return DT_LNK;
                break;
        case YAFFS_OBJECT_TYPE_HARDLINK:
                return DT_REG;
                break;
        case YAFFS_OBJECT_TYPE_SPECIAL:
                if (S_ISFIFO(obj->yst_mode))
                        return DT_FIFO;
                if (S_ISCHR(obj->yst_mode))
                        return DT_CHR;
                if (S_ISBLK(obj->yst_mode))
                        return DT_BLK;
                if (S_ISSOCK(obj->yst_mode))
                        return DT_SOCK;
                return DT_REG;
                break;
        default:
                return DT_REG;
                break;
        }
}

YCHAR *yaffs_get_symlink_alias(struct yaffs_obj *obj)
{
        obj = yaffs_get_equivalent_obj(obj);
        if (obj->variant_type == YAFFS_OBJECT_TYPE_SYMLINK)
                return yaffs_clone_str(obj->variant.symlink_variant.alias);
        else
                return yaffs_clone_str(_Y(""));
}

/*--------------------------- Initialisation code -------------------------- */

static int yaffs_check_dev_fns(struct yaffs_dev *dev)
{
        struct yaffs_driver *drv = &dev->drv;
        struct yaffs_tags_handler *tagger = &dev->tagger;

        /* Common functions, gotta have */
        if (!drv->drv_read_chunk_fn ||
            !drv->drv_write_chunk_fn ||
            !drv->drv_erase_fn)
                return 0;

        if (dev->param.is_yaffs2 &&
             (!drv->drv_mark_bad_fn  || !drv->drv_check_bad_fn))
                return 0;

        /* Install the default tags marshalling functions if needed. */
        yaffs_tags_compat_install(dev);
        yaffs_tags_marshall_install(dev);

        /* Check we now have the marshalling functions required. */
        if (!tagger->write_chunk_tags_fn ||
            !tagger->read_chunk_tags_fn ||
            !tagger->query_block_fn ||
            !tagger->mark_bad_fn)
                return 0;

        return 1;
}

static int yaffs_create_initial_dir(struct yaffs_dev *dev)
{
        /* Initialise the unlinked, deleted, root and lost+found directories */
        dev->lost_n_found = NULL;
        dev->root_dir = NULL;
        dev->unlinked_dir = NULL;
        dev->del_dir = NULL;

        dev->unlinked_dir =
            yaffs_create_fake_dir(dev, YAFFS_OBJECTID_UNLINKED, S_IFDIR);
        dev->del_dir =
            yaffs_create_fake_dir(dev, YAFFS_OBJECTID_DELETED, S_IFDIR);
        dev->root_dir =
            yaffs_create_fake_dir(dev, YAFFS_OBJECTID_ROOT,
                                  YAFFS_ROOT_MODE | S_IFDIR);
        dev->lost_n_found =
            yaffs_create_fake_dir(dev, YAFFS_OBJECTID_LOSTNFOUND,
                                  YAFFS_LOSTNFOUND_MODE | S_IFDIR);

        if (dev->lost_n_found &&
                dev->root_dir &&
                dev->unlinked_dir &&
                dev->del_dir) {
                        /* If lost-n-found is hidden then yank it out of the directory tree. */
                        if (dev->param.hide_lost_n_found)
                                list_del_init(&dev->lost_n_found->siblings);
                        else
                                yaffs_add_obj_to_dir(dev->root_dir, dev->lost_n_found);
                return YAFFS_OK;
        }
        return YAFFS_FAIL;
}

/* Low level init.
 * Typically only used by yaffs_guts_initialise, but also used by the
 * Low level yaffs driver tests.
 */

int yaffs_guts_ll_init(struct yaffs_dev *dev)
{


        yaffs_trace(YAFFS_TRACE_TRACING, "yaffs: yaffs_ll_init()");

        if (!dev) {
                yaffs_trace(YAFFS_TRACE_ALWAYS,
                        "yaffs: Need a device"
                        );
                return YAFFS_FAIL;
        }

        if (dev->ll_init)
                return YAFFS_OK;

        dev->internal_start_block = dev->param.start_block;
        dev->internal_end_block = dev->param.end_block;
        dev->block_offset = 0;
        dev->chunk_offset = 0;
        dev->n_free_chunks = 0;

        dev->gc_block = 0;

        if (dev->param.start_block == 0) {
                dev->internal_start_block = dev->param.start_block + 1;
                dev->internal_end_block = dev->param.end_block + 1;
                dev->block_offset = 1;
                dev->chunk_offset = dev->param.chunks_per_block;
        }

        /* Check geometry parameters. */

        if ((!dev->param.inband_tags && dev->param.is_yaffs2 &&
                dev->param.total_bytes_per_chunk < 1024) ||
                (!dev->param.is_yaffs2 &&
                        dev->param.total_bytes_per_chunk < 512) ||
                (dev->param.inband_tags && !dev->param.is_yaffs2) ||
                 dev->param.chunks_per_block < 2 ||
                 dev->param.n_reserved_blocks < 2 ||
                dev->internal_start_block <= 0 ||
                dev->internal_end_block <= 0 ||
                dev->internal_end_block <=
                (dev->internal_start_block + dev->param.n_reserved_blocks + 2)
                ) {
                /* otherwise it is too small */
                yaffs_trace(YAFFS_TRACE_ALWAYS,
                        "NAND geometry problems: chunk size %d, type is yaffs%s, inband_tags %d ",
                        dev->param.total_bytes_per_chunk,
                        dev->param.is_yaffs2 ? "2" : "",
                        dev->param.inband_tags);
                return YAFFS_FAIL;
        }

        /* Sort out space for inband tags, if required */
        if (dev->param.inband_tags)
                dev->data_bytes_per_chunk =
                    dev->param.total_bytes_per_chunk -
                    sizeof(struct yaffs_packed_tags2_tags_only);
        else
                dev->data_bytes_per_chunk = dev->param.total_bytes_per_chunk;

        /* Got the right mix of functions? */
        if (!yaffs_check_dev_fns(dev)) {
                /* Function missing */
                yaffs_trace(YAFFS_TRACE_ALWAYS,
                        "device function(s) missing or wrong");

                return YAFFS_FAIL;
        }

        if (yaffs_init_nand(dev) != YAFFS_OK) {
                yaffs_trace(YAFFS_TRACE_ALWAYS, "InitialiseNAND failed");
                return YAFFS_FAIL;
        }

        return YAFFS_OK;
}


int yaffs_guts_format_dev(struct yaffs_dev *dev)
{
        u32 i;
        enum yaffs_block_state state;
        u32 dummy;

        if(yaffs_guts_ll_init(dev) != YAFFS_OK)
                return YAFFS_FAIL;

        if(dev->is_mounted)
                return YAFFS_FAIL;

        for (i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
                yaffs_query_init_block_state(dev, i, &state, &dummy);
                if (state != YAFFS_BLOCK_STATE_DEAD)
                        yaffs_erase_block(dev, i);
        }

        return YAFFS_OK;
}


int yaffs_guts_initialise(struct yaffs_dev *dev)
{
        int init_failed = 0;
        u32 x;
        u32 bits;

        if(yaffs_guts_ll_init(dev) != YAFFS_OK)
                return YAFFS_FAIL;

        if (dev->is_mounted) {
                yaffs_trace(YAFFS_TRACE_ALWAYS, "device already mounted");
                return YAFFS_FAIL;
        }

        dev->is_mounted = 1;

        /* OK now calculate a few things for the device */

        /*
         *  Calculate all the chunk size manipulation numbers:
         */
        x = dev->data_bytes_per_chunk;
        /* We always use dev->chunk_shift and dev->chunk_div */
        dev->chunk_shift = calc_shifts(x);
        x >>= dev->chunk_shift;
        dev->chunk_div = x;
        /* We only use chunk mask if chunk_div is 1 */
        dev->chunk_mask = (1 << dev->chunk_shift) - 1;

        /*
         * Calculate chunk_grp_bits.
         * We need to find the next power of 2 > than internal_end_block
         */

        x = dev->param.chunks_per_block * (dev->internal_end_block + 1);

        bits = calc_shifts_ceiling(x);

        /* Set up tnode width if wide tnodes are enabled. */
        if (!dev->param.wide_tnodes_disabled) {
                /* bits must be even so that we end up with 32-bit words */
                if (bits & 1)
                        bits++;
                if (bits < 16)
                        dev->tnode_width = 16;
                else
                        dev->tnode_width = bits;
        } else {
                dev->tnode_width = 16;
        }

        dev->tnode_mask = (1 << dev->tnode_width) - 1;

        /* Level0 Tnodes are 16 bits or wider (if wide tnodes are enabled),
         * so if the bitwidth of the
         * chunk range we're using is greater than 16 we need
         * to figure out chunk shift and chunk_grp_size
         */

        if (bits <= dev->tnode_width)
                dev->chunk_grp_bits = 0;
        else
                dev->chunk_grp_bits = bits - dev->tnode_width;

        dev->tnode_size = (dev->tnode_width * YAFFS_NTNODES_LEVEL0) / 8;
        if (dev->tnode_size < sizeof(struct yaffs_tnode))
                dev->tnode_size = sizeof(struct yaffs_tnode);

        dev->chunk_grp_size = 1 << dev->chunk_grp_bits;

        if (dev->param.chunks_per_block < dev->chunk_grp_size) {
                /* We have a problem because the soft delete won't work if
                 * the chunk group size > chunks per block.
                 * This can be remedied by using larger "virtual blocks".
                 */
                yaffs_trace(YAFFS_TRACE_ALWAYS, "chunk group too large");

                return YAFFS_FAIL;
        }

        /* Finished verifying the device, continue with initialisation */

        /* More device initialisation */
        dev->all_gcs = 0;
        dev->passive_gc_count = 0;
        dev->oldest_dirty_gc_count = 0;
        dev->bg_gcs = 0;
        dev->gc_block_finder = 0;
        dev->buffered_block = -1;
        dev->doing_buffered_block_rewrite = 0;
        dev->n_deleted_files = 0;
        dev->n_bg_deletions = 0;
        dev->n_unlinked_files = 0;
        dev->n_ecc_fixed = 0;
        dev->n_ecc_unfixed = 0;
        dev->n_tags_ecc_fixed = 0;
        dev->n_tags_ecc_unfixed = 0;
        dev->n_erase_failures = 0;
        dev->n_erased_blocks = 0;
        dev->gc_disable = 0;
        dev->has_pending_prioritised_gc = 1; /* Assume the worst for now,
                                              * will get fixed on first GC */
        INIT_LIST_HEAD(&dev->dirty_dirs);
        dev->oldest_dirty_seq = 0;
        dev->oldest_dirty_block = 0;

        yaffs_endian_config(dev);

        /* Initialise temporary buffers and caches. */
        if (!yaffs_init_tmp_buffers(dev))
                init_failed = 1;

        dev->cache = NULL;
        dev->gc_cleanup_list = NULL;

        if (!init_failed && dev->param.n_caches > 0) {
                u32 i;
                void *buf;
                u32 cache_bytes =
                    dev->param.n_caches * sizeof(struct yaffs_cache);

                if (dev->param.n_caches > YAFFS_MAX_SHORT_OP_CACHES)
                        dev->param.n_caches = YAFFS_MAX_SHORT_OP_CACHES;

                dev->cache = kmalloc(cache_bytes, GFP_NOFS);

                buf = (u8 *) dev->cache;

                if (dev->cache)
                        memset(dev->cache, 0, cache_bytes);

                for (i = 0; i < dev->param.n_caches && buf; i++) {
                        dev->cache[i].object = NULL;
                        dev->cache[i].last_use = 0;
                        dev->cache[i].dirty = 0;
                        dev->cache[i].data = buf =
                            kmalloc(dev->param.total_bytes_per_chunk, GFP_NOFS);
                }
                if (!buf)
                        init_failed = 1;

                dev->cache_last_use = 0;
        }

        dev->cache_hits = 0;

        if (!init_failed) {
                dev->gc_cleanup_list =
                    kmalloc(dev->param.chunks_per_block * sizeof(u32),
                                        GFP_NOFS);
                if (!dev->gc_cleanup_list)
                        init_failed = 1;
        }

        if (dev->param.is_yaffs2)
                dev->param.use_header_file_size = 1;

        if (!init_failed && !yaffs_init_blocks(dev))
                init_failed = 1;

        yaffs_init_tnodes_and_objs(dev);

        if (!init_failed && !yaffs_create_initial_dir(dev))
                init_failed = 1;

        if (!init_failed && dev->param.is_yaffs2 &&
                !dev->param.disable_summary &&
                !yaffs_summary_init(dev))
                init_failed = 1;

        if (!init_failed) {
                /* Now scan the flash. */
                if (dev->param.is_yaffs2) {
                        if (yaffs2_checkpt_restore(dev)) {
                                yaffs_check_obj_details_loaded(dev->root_dir);
                                yaffs_trace(YAFFS_TRACE_CHECKPOINT |
                                        YAFFS_TRACE_MOUNT,
                                        "yaffs: restored from checkpoint"
                                        );
                        } else {

                                /* Clean up the mess caused by an aborted
                                 * checkpoint load then scan backwards.
                                 */
                                yaffs_deinit_blocks(dev);

                                yaffs_deinit_tnodes_and_objs(dev);

                                dev->n_erased_blocks = 0;
                                dev->n_free_chunks = 0;
                                dev->alloc_block = -1;
                                dev->alloc_page = -1;
                                dev->n_deleted_files = 0;
                                dev->n_unlinked_files = 0;
                                dev->n_bg_deletions = 0;

                                if (!init_failed && !yaffs_init_blocks(dev))
                                        init_failed = 1;

                                yaffs_init_tnodes_and_objs(dev);

                                if (!init_failed
                                    && !yaffs_create_initial_dir(dev))
                                        init_failed = 1;

                                if (!init_failed && !yaffs2_scan_backwards(dev))
                                        init_failed = 1;
                        }
                } else if (!yaffs1_scan(dev)) {
                        init_failed = 1;
                }

                yaffs_strip_deleted_objs(dev);
                yaffs_fix_hanging_objs(dev);
                if (dev->param.empty_lost_n_found)
                        yaffs_empty_l_n_f(dev);
        }

        if (init_failed) {
                /* Clean up the mess */
                yaffs_trace(YAFFS_TRACE_TRACING,
                  "yaffs: yaffs_guts_initialise() aborted.");

                yaffs_deinitialise(dev);
                return YAFFS_FAIL;
        }

        /* Zero out stats */
        dev->n_page_reads = 0;
        dev->n_page_writes = 0;
        dev->n_erasures = 0;
        dev->n_gc_copies = 0;
        dev->n_retried_writes = 0;

        dev->n_retired_blocks = 0;

        yaffs_verify_free_chunks(dev);
        yaffs_verify_blocks(dev);

        /* Clean up any aborted checkpoint data */
        if (!dev->is_checkpointed && dev->blocks_in_checkpt > 0)
                yaffs2_checkpt_invalidate(dev);

        yaffs_trace(YAFFS_TRACE_TRACING,
          "yaffs: yaffs_guts_initialise() done.");
        return YAFFS_OK;
}

void yaffs_deinitialise(struct yaffs_dev *dev)
{
        if (dev->is_mounted) {
                u32 i;

                yaffs_deinit_blocks(dev);
                yaffs_deinit_tnodes_and_objs(dev);
                yaffs_summary_deinit(dev);

                if (dev->param.n_caches > 0 && dev->cache) {

                        for (i = 0; i < dev->param.n_caches; i++) {
                                kfree(dev->cache[i].data);
                                dev->cache[i].data = NULL;
                        }

                        kfree(dev->cache);
                        dev->cache = NULL;
                }

                kfree(dev->gc_cleanup_list);

                for (i = 0; i < YAFFS_N_TEMP_BUFFERS; i++) {
                        kfree(dev->temp_buffer[i].buffer);
                        dev->temp_buffer[i].buffer = NULL;
                }

                kfree(dev->checkpt_buffer);
                dev->checkpt_buffer = NULL;
                kfree(dev->checkpt_block_list);
                dev->checkpt_block_list = NULL;

                dev->is_mounted = 0;

                yaffs_deinit_nand(dev);
        }
}

int yaffs_count_free_chunks(struct yaffs_dev *dev)
{
        int n_free = 0;
        u32 b;
        struct yaffs_block_info *blk;

        blk = dev->block_info;
        for (b = dev->internal_start_block; b <= dev->internal_end_block; b++) {
                switch (blk->block_state) {
                case YAFFS_BLOCK_STATE_EMPTY:
                case YAFFS_BLOCK_STATE_ALLOCATING:
                case YAFFS_BLOCK_STATE_COLLECTING:
                case YAFFS_BLOCK_STATE_FULL:
                        n_free +=
                            (dev->param.chunks_per_block - blk->pages_in_use +
                             blk->soft_del_pages);
                        break;
                default:
                        break;
                }
                blk++;
        }
        return n_free;
}

int yaffs_get_n_free_chunks(struct yaffs_dev *dev)
{
        /* This is what we report to the outside world */
        int n_free;
        int n_dirty_caches;
        int blocks_for_checkpt;
        u32 i;

        n_free = dev->n_free_chunks;
        n_free += dev->n_deleted_files;

        /* Now count and subtract the number of dirty chunks in the cache. */

        for (n_dirty_caches = 0, i = 0; i < dev->param.n_caches; i++) {
                if (dev->cache[i].dirty)
                        n_dirty_caches++;
        }

        n_free -= n_dirty_caches;

        n_free -=
            ((dev->param.n_reserved_blocks + 1) * dev->param.chunks_per_block);

        /* Now figure checkpoint space and report that... */
        blocks_for_checkpt = yaffs_calc_checkpt_blocks_required(dev);

        n_free -= (blocks_for_checkpt * dev->param.chunks_per_block);

        if (n_free < 0)
                n_free = 0;

        return n_free;
}


/*
 * Marshalling functions to get loff_t file sizes into and out of
 * object headers.
 */
void yaffs_oh_size_load(struct yaffs_dev *dev,
                        struct yaffs_obj_hdr *oh,
                        loff_t fsize,
                        int do_endian)
{
        oh->file_size_low = FSIZE_LOW(fsize);

        oh->file_size_high = FSIZE_HIGH(fsize);

        if (do_endian) {
                yaffs_do_endian_u32(dev, &oh->file_size_low);
                yaffs_do_endian_u32(dev, &oh->file_size_high);
        }
}

loff_t yaffs_oh_to_size(struct yaffs_dev *dev, struct yaffs_obj_hdr *oh,
                        int do_endian)
{
        loff_t retval;


        if (sizeof(loff_t) >= 8 && ~(oh->file_size_high)) {
                u32 low = oh->file_size_low;
                u32 high = oh->file_size_high;

                if (do_endian) {
                        yaffs_do_endian_u32 (dev, &low);
                        yaffs_do_endian_u32 (dev, &high);
                }
                retval = FSIZE_COMBINE(high, low);
        } else {
                u32 low = oh->file_size_low;

                if (do_endian)
                        yaffs_do_endian_u32(dev, &low);
                retval = (loff_t)low;
        }

        return retval;
}


void yaffs_count_blocks_by_state(struct yaffs_dev *dev, int bs[10])
{
        u32 i;
        struct yaffs_block_info *bi;
        int s;

        for(i = 0; i < 10; i++)
                bs[i] = 0;

        for(i = dev->internal_start_block; i <= dev->internal_end_block; i++) {
                bi = yaffs_get_block_info(dev, i);
                s = bi->block_state;
                if(s > YAFFS_BLOCK_STATE_DEAD || s < YAFFS_BLOCK_STATE_UNKNOWN)
                        bs[0]++;
                else
                        bs[s]++;
        }
}