/*
 * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
 *
 * Copyright (C) 2002-2011 Aleph One Ltd.
 *   for Toby Churchill Ltd and Brightstar Engineering
 *
 * Created by Charles Manning <charles@aleph1.co.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include "yaffs_yaffs1.h"
#include "yportenv.h"
#include "yaffs_trace.h"
#include "yaffs_bitmap.h"
#include "yaffs_getblockinfo.h"
#include "yaffs_nand.h"
#include "yaffs_attribs.h"

int yaffs1_scan(struct yaffs_dev *dev)
{
        struct yaffs_ext_tags tags;
        int blk;
        int chunk;
        int c;
        int deleted;
        enum yaffs_block_state state;
        LIST_HEAD(hard_list);
        struct yaffs_block_info *bi;
        u32 seq_number;
        struct yaffs_obj_hdr *oh;
        struct yaffs_obj *in;
        struct yaffs_obj *parent;
        int alloc_failed = 0;
        struct yaffs_shadow_fixer *shadow_fixers = NULL;
        u8 *chunk_data;

        yaffs_trace(YAFFS_TRACE_SCAN,
                "yaffs1_scan starts  intstartblk %d intendblk %d...",
                dev->internal_start_block, dev->internal_end_block);

        chunk_data = yaffs_get_temp_buffer(dev);

        dev->seq_number = YAFFS_LOWEST_SEQUENCE_NUMBER;

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

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

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

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

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

                if (state == YAFFS_BLOCK_STATE_DEAD) {
                        yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
                                "block %d is bad", blk);
                } else if (state == YAFFS_BLOCK_STATE_EMPTY) {
                        yaffs_trace(YAFFS_TRACE_SCAN_DEBUG, "Block empty ");
                        dev->n_erased_blocks++;
                        dev->n_free_chunks += dev->param.chunks_per_block;
                }
                bi++;
        }

        /* For each block.... */
        for (blk = dev->internal_start_block;
             !alloc_failed && blk <= dev->internal_end_block; blk++) {

                cond_resched();

                bi = yaffs_get_block_info(dev, blk);
                state = bi->block_state;

                deleted = 0;

                /* For each chunk in each block that needs scanning.... */
                for (c = 0;
                        !alloc_failed && c < dev->param.chunks_per_block &&
                        state == YAFFS_BLOCK_STATE_NEEDS_SCAN; c++) {
                        /* Read the tags and decide what to do */
                        chunk = blk * dev->param.chunks_per_block + c;

                        yaffs_rd_chunk_tags_nand(dev, chunk, NULL, &tags);

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

                        if (tags.ecc_result == YAFFS_ECC_RESULT_UNFIXED ||
                            tags.is_deleted) {
                                /* YAFFS1 only...
                                 * A deleted chunk
                                 */
                                deleted++;
                                dev->n_free_chunks++;
                        } else if (!tags.chunk_used) {
                                /* An unassigned chunk in the block
                                 * This means that either the block is empty or
                                 * this is the one being allocated from
                                 */

                                if (c == 0) {
                                        /* We're looking at the first chunk in
                                         *the block so the block is unused */
                                        state = YAFFS_BLOCK_STATE_EMPTY;
                                        dev->n_erased_blocks++;
                                } else {
                                        /* this is the block being allocated */
                                        yaffs_trace(YAFFS_TRACE_SCAN,
                                                " Allocating from %d %d",
                                                blk, c);
                                        state = YAFFS_BLOCK_STATE_ALLOCATING;
                                        dev->alloc_block = blk;
                                        dev->alloc_page = c;
                                        dev->alloc_block_finder = blk;

                                }

                                dev->n_free_chunks +=
                                    (dev->param.chunks_per_block - c);
                        } else if (tags.chunk_id > 0) {
                                /* chunk_id > 0 so it is a data chunk... */
                                unsigned int endpos;

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

                                in = yaffs_find_or_create_by_number(dev,
                                                        tags.obj_id,
                                                        YAFFS_OBJECT_TYPE_FILE);
                                /* PutChunkIntoFile checks for a clash
                                 * (two data chunks with the same chunk_id).
                                 */

                                if (!in)
                                        alloc_failed = 1;

                                if (in) {
                                        if (!yaffs_put_chunk_in_file
                                            (in, tags.chunk_id, chunk, 1))
                                                alloc_failed = 1;
                                }

                                endpos =
                                    (tags.chunk_id - 1) *
                                    dev->data_bytes_per_chunk +
                                    tags.n_bytes;
                                if (in &&
                                    in->variant_type ==
                                     YAFFS_OBJECT_TYPE_FILE &&
                                    in->variant.file_variant.scanned_size <
                                      endpos) {
                                        in->variant.file_variant.scanned_size =
                                            endpos;
                                        if (!dev->param.use_header_file_size) {
                                                in->variant.
                                                    file_variant.file_size =
                                                    in->variant.
                                                    file_variant.scanned_size;
                                        }

                                }
                        } else {
                                /* chunk_id == 0, so it is an ObjectHeader.
                                 * Make the object
                                 */
                                yaffs_set_chunk_bit(dev, blk, c);
                                bi->pages_in_use++;

                                yaffs_rd_chunk_tags_nand(dev, chunk,
                                                         chunk_data, NULL);

                                oh = (struct yaffs_obj_hdr *)chunk_data;

                                in = yaffs_find_by_number(dev, tags.obj_id);
                                if (in && in->variant_type != oh->type) {
                                        /* This should not happen, but somehow
                                         * Wev'e ended up with an obj_id that
                                         * has been reused but not yet deleted,
                                         * and worse still it has changed type.
                                         * Delete the old object.
                                         */

                                        yaffs_del_obj(in);
                                        in = NULL;
                                }

                                in = yaffs_find_or_create_by_number(dev,
                                                                tags.obj_id,
                                                                oh->type);

                                if (!in)
                                        alloc_failed = 1;

                                if (in && oh->shadows_obj > 0) {

                                        struct yaffs_shadow_fixer *fixer;
                                        fixer =
                                                kmalloc(sizeof
                                                (struct yaffs_shadow_fixer),
                                                GFP_NOFS);
                                        if (fixer) {
                                                fixer->next = shadow_fixers;
                                                shadow_fixers = fixer;
                                                fixer->obj_id = tags.obj_id;
                                                fixer->shadowed_id =
                                                    oh->shadows_obj;
                                                yaffs_trace(YAFFS_TRACE_SCAN,
                                                        " Shadow fixer: %d shadows %d",
                                                        fixer->obj_id,
                                                        fixer->shadowed_id);

                                        }

                                }

                                if (in && in->valid) {
                                        /* We have already filled this one.
                                         * We have a duplicate and need to
                                         * resolve it. */

                                        unsigned existing_serial = in->serial;
                                        unsigned new_serial =
                                            tags.serial_number;

                                        if (((existing_serial + 1) & 3) ==
                                            new_serial) {
                                                /* Use new one - destroy the
                                                 * exisiting one */
                                                yaffs_chunk_del(dev,
                                                                in->hdr_chunk,
                                                                1, __LINE__);
                                                in->valid = 0;
                                        } else {
                                                /* Use existing - destroy
                                                 * this one. */
                                                yaffs_chunk_del(dev, chunk, 1,
                                                                __LINE__);
                                        }
                                }

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

                                        in->yst_mode = oh->yst_mode;
                                        yaffs_load_attribs(in, oh);
                                        in->hdr_chunk = chunk;
                                        in->serial = tags.serial_number;

                                } else if (in && !in->valid) {
                                        /* we need to load this info */

                                        in->valid = 1;
                                        in->variant_type = oh->type;

                                        in->yst_mode = oh->yst_mode;
                                        yaffs_load_attribs(in, oh);
                                        in->hdr_chunk = chunk;
                                        in->serial = tags.serial_number;

                                        yaffs_set_obj_name_from_oh(in, oh);
                                        in->dirty = 0;

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

                                        parent =
                                            yaffs_find_or_create_by_number
                                            (dev, oh->parent_obj_id,
                                             YAFFS_OBJECT_TYPE_DIRECTORY);
                                        if (!parent)
                                                alloc_failed = 1;
                                        if (parent && parent->variant_type ==
                                            YAFFS_OBJECT_TYPE_UNKNOWN) {
                                                /* Set up as a directory */
                                                parent->variant_type =
                                                    YAFFS_OBJECT_TYPE_DIRECTORY;
                                                INIT_LIST_HEAD(&parent->
                                                        variant.dir_variant.
                                                        children);
                                        } else if (!parent ||
                                                parent->variant_type !=
                                                YAFFS_OBJECT_TYPE_DIRECTORY) {
                                                /* Hoosterman, a problem....
                                                 * We're trying to use a
                                                 * non-directory as a directory
                                                 */

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

                                        yaffs_add_obj_to_dir(parent, in);

                                        switch (in->variant_type) {
                                        case YAFFS_OBJECT_TYPE_UNKNOWN:
                                                /* Todo got a problem */
                                                break;
                                        case YAFFS_OBJECT_TYPE_FILE:
                                                if (dev->param.
                                                    use_header_file_size)
                                                        in->variant.
                                                        file_variant.file_size
                                                        = yaffs_oh_to_size(oh);
                                                break;
                                        case YAFFS_OBJECT_TYPE_HARDLINK:
                                                in->variant.
                                                    hardlink_variant.equiv_id =
                                                    oh->equiv_id;
                                                list_add(&in->hard_links,
                                                                &hard_list);
                                                break;
                                        case YAFFS_OBJECT_TYPE_DIRECTORY:
                                                /* Do nothing */
                                                break;
                                        case YAFFS_OBJECT_TYPE_SPECIAL:
                                                /* Do nothing */
                                                break;
                                        case YAFFS_OBJECT_TYPE_SYMLINK:
                                                in->variant.symlink_variant.
                                                    alias =
                                                    yaffs_clone_str(oh->alias);
                                                if (!in->variant.
                                                    symlink_variant.alias)
                                                        alloc_failed = 1;
                                                break;
                                        }
                                }
                        }
                }

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

                if (state == YAFFS_BLOCK_STATE_ALLOCATING) {
                        /* If the block was partially allocated then
                         * treat it as fully allocated. */
                        state = YAFFS_BLOCK_STATE_FULL;
                        dev->alloc_block = -1;
                }

                bi->block_state = state;

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

        /* Ok, we've done all the scanning.
         * Fix up the hard link chains.
         * We should now have scanned all the objects, now it's time to add
         * these hardlinks.
         */

        yaffs_link_fixup(dev, &hard_list);

        /*
         * Fix up any shadowed objects.
         * There should not be more than one of these.
         */
        {
                struct yaffs_shadow_fixer *fixer;
                struct yaffs_obj *obj;

                while (shadow_fixers) {
                        fixer = shadow_fixers;
                        shadow_fixers = fixer->next;
                        /* Complete the rename transaction by deleting the
                         * shadowed object then setting the object header
                         to unshadowed.
                         */
                        obj = yaffs_find_by_number(dev, fixer->shadowed_id);
                        if (obj)
                                yaffs_del_obj(obj);

                        obj = yaffs_find_by_number(dev, fixer->obj_id);

                        if (obj)
                                yaffs_update_oh(obj, NULL, 1, 0, 0, NULL);

                        kfree(fixer);
                }
        }

        yaffs_release_temp_buffer(dev, chunk_data);

        if (alloc_failed)
                return YAFFS_FAIL;

        yaffs_trace(YAFFS_TRACE_SCAN, "yaffs1_scan ends");

        return YAFFS_OK;
}