/*
 * Copyright (c) 2012 Linutronix GmbH
 * Copyright (c) 2014 sigma star gmbh
 * Author: Richard Weinberger <richard@nod.at>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 *
 */

#include <linux/crc32.h>
#include <linux/bitmap.h>
#include "ubi.h"

/**
 * init_seen - allocate memory for used for debugging.
 * @ubi: UBI device description object
 */
static inline unsigned long *init_seen(struct ubi_device *ubi)
{
        unsigned long *ret;

        if (!ubi_dbg_chk_fastmap(ubi))
                return NULL;

        ret = kcalloc(BITS_TO_LONGS(ubi->peb_count), sizeof(unsigned long),
                      GFP_KERNEL);
        if (!ret)
                return ERR_PTR(-ENOMEM);

        return ret;
}

/**
 * free_seen - free the seen logic integer array.
 * @seen: integer array of @ubi->peb_count size
 */
static inline void free_seen(unsigned long *seen)
{
        kfree(seen);
}

/**
 * set_seen - mark a PEB as seen.
 * @ubi: UBI device description object
 * @pnum: The PEB to be makred as seen
 * @seen: integer array of @ubi->peb_count size
 */
static inline void set_seen(struct ubi_device *ubi, int pnum, unsigned long *seen)
{
        if (!ubi_dbg_chk_fastmap(ubi) || !seen)
                return;

        set_bit(pnum, seen);
}

/**
 * self_check_seen - check whether all PEB have been seen by fastmap.
 * @ubi: UBI device description object
 * @seen: integer array of @ubi->peb_count size
 */
static int self_check_seen(struct ubi_device *ubi, unsigned long *seen)
{
        int pnum, ret = 0;

        if (!ubi_dbg_chk_fastmap(ubi) || !seen)
                return 0;

        for (pnum = 0; pnum < ubi->peb_count; pnum++) {
                if (test_bit(pnum, seen) && ubi->lookuptbl[pnum]) {
                        ubi_err(ubi, "self-check failed for PEB %d, fastmap didn't see it", pnum);
                        ret = -EINVAL;
                }
        }

        return ret;
}

/**
 * ubi_calc_fm_size - calculates the fastmap size in bytes for an UBI device.
 * @ubi: UBI device description object
 */
size_t ubi_calc_fm_size(struct ubi_device *ubi)
{
        size_t size;

        size = sizeof(struct ubi_fm_sb) +
                sizeof(struct ubi_fm_hdr) +
                sizeof(struct ubi_fm_scan_pool) +
                sizeof(struct ubi_fm_scan_pool) +
                (ubi->peb_count * sizeof(struct ubi_fm_ec)) +
                (sizeof(struct ubi_fm_eba) +
                (ubi->peb_count * sizeof(__be32))) +
                sizeof(struct ubi_fm_volhdr) * UBI_MAX_VOLUMES;
        return roundup(size, ubi->leb_size);
}


/**
 * new_fm_vhdr - allocate a new volume header for fastmap usage.
 * @ubi: UBI device description object
 * @vol_id: the VID of the new header
 *
 * Returns a new struct ubi_vid_hdr on success.
 * NULL indicates out of memory.
 */
static struct ubi_vid_io_buf *new_fm_vbuf(struct ubi_device *ubi, int vol_id)
{
        struct ubi_vid_io_buf *new;
        struct ubi_vid_hdr *vh;

        new = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
        if (!new)
                goto out;

        vh = ubi_get_vid_hdr(new);
        vh->vol_type = UBI_VID_DYNAMIC;
        vh->vol_id = cpu_to_be32(vol_id);

        /* UBI implementations without fastmap support have to delete the
         * fastmap.
         */
        vh->compat = UBI_COMPAT_DELETE;

out:
        return new;
}

/**
 * add_aeb - create and add a attach erase block to a given list.
 * @ai: UBI attach info object
 * @list: the target list
 * @pnum: PEB number of the new attach erase block
 * @ec: erease counter of the new LEB
 * @scrub: scrub this PEB after attaching
 *
 * Returns 0 on success, < 0 indicates an internal error.
 */
static int add_aeb(struct ubi_attach_info *ai, struct list_head *list,
                   int pnum, int ec, int scrub)
{
        struct ubi_ainf_peb *aeb;

        aeb = ubi_alloc_aeb(ai, pnum, ec);
        if (!aeb)
                return -ENOMEM;

        aeb->lnum = -1;
        aeb->scrub = scrub;
        aeb->copy_flag = aeb->sqnum = 0;

        ai->ec_sum += aeb->ec;
        ai->ec_count++;

        if (ai->max_ec < aeb->ec)
                ai->max_ec = aeb->ec;

        if (ai->min_ec > aeb->ec)
                ai->min_ec = aeb->ec;

        list_add_tail(&aeb->u.list, list);

        return 0;
}

/**
 * add_vol - create and add a new volume to ubi_attach_info.
 * @ai: ubi_attach_info object
 * @vol_id: VID of the new volume
 * @used_ebs: number of used EBS
 * @data_pad: data padding value of the new volume
 * @vol_type: volume type
 * @last_eb_bytes: number of bytes in the last LEB
 *
 * Returns the new struct ubi_ainf_volume on success.
 * NULL indicates an error.
 */
static struct ubi_ainf_volume *add_vol(struct ubi_attach_info *ai, int vol_id,
                                       int used_ebs, int data_pad, u8 vol_type,
                                       int last_eb_bytes)
{
        struct ubi_ainf_volume *av;

        av = ubi_add_av(ai, vol_id);
        if (IS_ERR(av))
                return av;

        av->data_pad = data_pad;
        av->last_data_size = last_eb_bytes;
        av->compat = 0;
        av->vol_type = vol_type;
        if (av->vol_type == UBI_STATIC_VOLUME)
                av->used_ebs = used_ebs;

        dbg_bld("found volume (ID %i)", vol_id);
        return av;
}

/**
 * assign_aeb_to_av - assigns a SEB to a given ainf_volume and removes it
 * from it's original list.
 * @ai: ubi_attach_info object
 * @aeb: the to be assigned SEB
 * @av: target scan volume
 */
static void assign_aeb_to_av(struct ubi_attach_info *ai,
                             struct ubi_ainf_peb *aeb,
                             struct ubi_ainf_volume *av)
{
        struct ubi_ainf_peb *tmp_aeb;
        struct rb_node **p = &ai->volumes.rb_node, *parent = NULL;

        p = &av->root.rb_node;
        while (*p) {
                parent = *p;

                tmp_aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);
                if (aeb->lnum != tmp_aeb->lnum) {
                        if (aeb->lnum < tmp_aeb->lnum)
                                p = &(*p)->rb_left;
                        else
                                p = &(*p)->rb_right;

                        continue;
                } else
                        break;
        }

        list_del(&aeb->u.list);
        av->leb_count++;

        rb_link_node(&aeb->u.rb, parent, p);
        rb_insert_color(&aeb->u.rb, &av->root);
}

/**
 * update_vol - inserts or updates a LEB which was found a pool.
 * @ubi: the UBI device object
 * @ai: attach info object
 * @av: the volume this LEB belongs to
 * @new_vh: the volume header derived from new_aeb
 * @new_aeb: the AEB to be examined
 *
 * Returns 0 on success, < 0 indicates an internal error.
 */
static int update_vol(struct ubi_device *ubi, struct ubi_attach_info *ai,
                      struct ubi_ainf_volume *av, struct ubi_vid_hdr *new_vh,
                      struct ubi_ainf_peb *new_aeb)
{
        struct rb_node **p = &av->root.rb_node, *parent = NULL;
        struct ubi_ainf_peb *aeb, *victim;
        int cmp_res;

        while (*p) {
                parent = *p;
                aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);

                if (be32_to_cpu(new_vh->lnum) != aeb->lnum) {
                        if (be32_to_cpu(new_vh->lnum) < aeb->lnum)
                                p = &(*p)->rb_left;
                        else
                                p = &(*p)->rb_right;

                        continue;
                }

                /* This case can happen if the fastmap gets written
                 * because of a volume change (creation, deletion, ..).
                 * Then a PEB can be within the persistent EBA and the pool.
                 */
                if (aeb->pnum == new_aeb->pnum) {
                        ubi_assert(aeb->lnum == new_aeb->lnum);
                        ubi_free_aeb(ai, new_aeb);

                        return 0;
                }

                cmp_res = ubi_compare_lebs(ubi, aeb, new_aeb->pnum, new_vh);
                if (cmp_res < 0)
                        return cmp_res;

                /* new_aeb is newer */
                if (cmp_res & 1) {
                        victim = ubi_alloc_aeb(ai, aeb->pnum, aeb->ec);
                        if (!victim)
                                return -ENOMEM;

                        list_add_tail(&victim->u.list, &ai->erase);

                        if (av->highest_lnum == be32_to_cpu(new_vh->lnum))
                                av->last_data_size =
                                        be32_to_cpu(new_vh->data_size);

                        dbg_bld("vol %i: AEB %i's PEB %i is the newer",
                                av->vol_id, aeb->lnum, new_aeb->pnum);

                        aeb->ec = new_aeb->ec;
                        aeb->pnum = new_aeb->pnum;
                        aeb->copy_flag = new_vh->copy_flag;
                        aeb->scrub = new_aeb->scrub;
                        aeb->sqnum = new_aeb->sqnum;
                        ubi_free_aeb(ai, new_aeb);

                /* new_aeb is older */
                } else {
                        dbg_bld("vol %i: AEB %i's PEB %i is old, dropping it",
                                av->vol_id, aeb->lnum, new_aeb->pnum);
                        list_add_tail(&new_aeb->u.list, &ai->erase);
                }

                return 0;
        }
        /* This LEB is new, let's add it to the volume */

        if (av->highest_lnum <= be32_to_cpu(new_vh->lnum)) {
                av->highest_lnum = be32_to_cpu(new_vh->lnum);
                av->last_data_size = be32_to_cpu(new_vh->data_size);
        }

        if (av->vol_type == UBI_STATIC_VOLUME)
                av->used_ebs = be32_to_cpu(new_vh->used_ebs);

        av->leb_count++;

        rb_link_node(&new_aeb->u.rb, parent, p);
        rb_insert_color(&new_aeb->u.rb, &av->root);

        return 0;
}

/**
 * process_pool_aeb - we found a non-empty PEB in a pool.
 * @ubi: UBI device object
 * @ai: attach info object
 * @new_vh: the volume header derived from new_aeb
 * @new_aeb: the AEB to be examined
 *
 * Returns 0 on success, < 0 indicates an internal error.
 */
static int process_pool_aeb(struct ubi_device *ubi, struct ubi_attach_info *ai,
                            struct ubi_vid_hdr *new_vh,
                            struct ubi_ainf_peb *new_aeb)
{
        int vol_id = be32_to_cpu(new_vh->vol_id);
        struct ubi_ainf_volume *av;

        if (vol_id == UBI_FM_SB_VOLUME_ID || vol_id == UBI_FM_DATA_VOLUME_ID) {
                ubi_free_aeb(ai, new_aeb);

                return 0;
        }

        /* Find the volume this SEB belongs to */
        av = ubi_find_av(ai, vol_id);
        if (!av) {
                ubi_err(ubi, "orphaned volume in fastmap pool!");
                ubi_free_aeb(ai, new_aeb);
                return UBI_BAD_FASTMAP;
        }

        ubi_assert(vol_id == av->vol_id);

        return update_vol(ubi, ai, av, new_vh, new_aeb);
}

/**
 * unmap_peb - unmap a PEB.
 * If fastmap detects a free PEB in the pool it has to check whether
 * this PEB has been unmapped after writing the fastmap.
 *
 * @ai: UBI attach info object
 * @pnum: The PEB to be unmapped
 */
static void unmap_peb(struct ubi_attach_info *ai, int pnum)
{
        struct ubi_ainf_volume *av;
        struct rb_node *node, *node2;
        struct ubi_ainf_peb *aeb;

        ubi_rb_for_each_entry(node, av, &ai->volumes, rb) {
                ubi_rb_for_each_entry(node2, aeb, &av->root, u.rb) {
                        if (aeb->pnum == pnum) {
                                rb_erase(&aeb->u.rb, &av->root);
                                av->leb_count--;
                                ubi_free_aeb(ai, aeb);
                                return;
                        }
                }
        }
}

/**
 * scan_pool - scans a pool for changed (no longer empty PEBs).
 * @ubi: UBI device object
 * @ai: attach info object
 * @pebs: an array of all PEB numbers in the to be scanned pool
 * @pool_size: size of the pool (number of entries in @pebs)
 * @max_sqnum: pointer to the maximal sequence number
 * @free: list of PEBs which are most likely free (and go into @ai->free)
 *
 * Returns 0 on success, if the pool is unusable UBI_BAD_FASTMAP is returned.
 * < 0 indicates an internal error.
 */
static int scan_pool(struct ubi_device *ubi, struct ubi_attach_info *ai,
                     __be32 *pebs, int pool_size, unsigned long long *max_sqnum,
                     struct list_head *free)
{
        struct ubi_vid_io_buf *vb;
        struct ubi_vid_hdr *vh;
        struct ubi_ec_hdr *ech;
        struct ubi_ainf_peb *new_aeb;
        int i, pnum, err, ret = 0;

        ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
        if (!ech)
                return -ENOMEM;

        vb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
        if (!vb) {
                kfree(ech);
                return -ENOMEM;
        }

        vh = ubi_get_vid_hdr(vb);

        dbg_bld("scanning fastmap pool: size = %i", pool_size);

        /*
         * Now scan all PEBs in the pool to find changes which have been made
         * after the creation of the fastmap
         */
        for (i = 0; i < pool_size; i++) {
                int scrub = 0;
                int image_seq;

                pnum = be32_to_cpu(pebs[i]);

                if (ubi_io_is_bad(ubi, pnum)) {
                        ubi_err(ubi, "bad PEB in fastmap pool!");
                        ret = UBI_BAD_FASTMAP;
                        goto out;
                }

                err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
                if (err && err != UBI_IO_BITFLIPS) {
                        ubi_err(ubi, "unable to read EC header! PEB:%i err:%i",
                                pnum, err);
                        ret = err > 0 ? UBI_BAD_FASTMAP : err;
                        goto out;
                } else if (err == UBI_IO_BITFLIPS)
                        scrub = 1;

                /*
                 * Older UBI implementations have image_seq set to zero, so
                 * we shouldn't fail if image_seq == 0.
                 */
                image_seq = be32_to_cpu(ech->image_seq);

                if (image_seq && (image_seq != ubi->image_seq)) {
                        ubi_err(ubi, "bad image seq: 0x%x, expected: 0x%x",
                                be32_to_cpu(ech->image_seq), ubi->image_seq);
                        ret = UBI_BAD_FASTMAP;
                        goto out;
                }

                err = ubi_io_read_vid_hdr(ubi, pnum, vb, 0);
                if (err == UBI_IO_FF || err == UBI_IO_FF_BITFLIPS) {
                        unsigned long long ec = be64_to_cpu(ech->ec);
                        unmap_peb(ai, pnum);
                        dbg_bld("Adding PEB to free: %i", pnum);

                        if (err == UBI_IO_FF_BITFLIPS)
                                scrub = 1;

                        add_aeb(ai, free, pnum, ec, scrub);
                        continue;
                } else if (err == 0 || err == UBI_IO_BITFLIPS) {
                        dbg_bld("Found non empty PEB:%i in pool", pnum);

                        if (err == UBI_IO_BITFLIPS)
                                scrub = 1;

                        new_aeb = ubi_alloc_aeb(ai, pnum, be64_to_cpu(ech->ec));
                        if (!new_aeb) {
                                ret = -ENOMEM;
                                goto out;
                        }

                        new_aeb->lnum = be32_to_cpu(vh->lnum);
                        new_aeb->sqnum = be64_to_cpu(vh->sqnum);
                        new_aeb->copy_flag = vh->copy_flag;
                        new_aeb->scrub = scrub;

                        if (*max_sqnum < new_aeb->sqnum)
                                *max_sqnum = new_aeb->sqnum;

                        err = process_pool_aeb(ubi, ai, vh, new_aeb);
                        if (err) {
                                ret = err > 0 ? UBI_BAD_FASTMAP : err;
                                goto out;
                        }
                } else {
                        /* We are paranoid and fall back to scanning mode */
                        ubi_err(ubi, "fastmap pool PEBs contains damaged PEBs!");
                        ret = err > 0 ? UBI_BAD_FASTMAP : err;
                        goto out;
                }

        }

out:
        ubi_free_vid_buf(vb);
        kfree(ech);
        return ret;
}

/**
 * count_fastmap_pebs - Counts the PEBs found by fastmap.
 * @ai: The UBI attach info object
 */
static int count_fastmap_pebs(struct ubi_attach_info *ai)
{
        struct ubi_ainf_peb *aeb;
        struct ubi_ainf_volume *av;
        struct rb_node *rb1, *rb2;
        int n = 0;

        list_for_each_entry(aeb, &ai->erase, u.list)
                n++;

        list_for_each_entry(aeb, &ai->free, u.list)
                n++;

        ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb)
                ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
                        n++;

        return n;
}

/**
 * ubi_attach_fastmap - creates ubi_attach_info from a fastmap.
 * @ubi: UBI device object
 * @ai: UBI attach info object
 * @fm: the fastmap to be attached
 *
 * Returns 0 on success, UBI_BAD_FASTMAP if the found fastmap was unusable.
 * < 0 indicates an internal error.
 */
static int ubi_attach_fastmap(struct ubi_device *ubi,
                              struct ubi_attach_info *ai,
                              struct ubi_fastmap_layout *fm)
{
        struct list_head used, free;
        struct ubi_ainf_volume *av;
        struct ubi_ainf_peb *aeb, *tmp_aeb, *_tmp_aeb;
        struct ubi_fm_sb *fmsb;
        struct ubi_fm_hdr *fmhdr;
        struct ubi_fm_scan_pool *fmpl, *fmpl_wl;
        struct ubi_fm_ec *fmec;
        struct ubi_fm_volhdr *fmvhdr;
        struct ubi_fm_eba *fm_eba;
        int ret, i, j, pool_size, wl_pool_size;
        size_t fm_pos = 0, fm_size = ubi->fm_size;
        unsigned long long max_sqnum = 0;
        void *fm_raw = ubi->fm_buf;

        INIT_LIST_HEAD(&used);
        INIT_LIST_HEAD(&free);
        ai->min_ec = UBI_MAX_ERASECOUNTER;

        fmsb = (struct ubi_fm_sb *)(fm_raw);
        ai->max_sqnum = fmsb->sqnum;
        fm_pos += sizeof(struct ubi_fm_sb);
        if (fm_pos >= fm_size)
                goto fail_bad;

        fmhdr = (struct ubi_fm_hdr *)(fm_raw + fm_pos);
        fm_pos += sizeof(*fmhdr);
        if (fm_pos >= fm_size)
                goto fail_bad;

        if (be32_to_cpu(fmhdr->magic) != UBI_FM_HDR_MAGIC) {
                ubi_err(ubi, "bad fastmap header magic: 0x%x, expected: 0x%x",
                        be32_to_cpu(fmhdr->magic), UBI_FM_HDR_MAGIC);
                goto fail_bad;
        }

        fmpl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
        fm_pos += sizeof(*fmpl);
        if (fm_pos >= fm_size)
                goto fail_bad;
        if (be32_to_cpu(fmpl->magic) != UBI_FM_POOL_MAGIC) {
                ubi_err(ubi, "bad fastmap pool magic: 0x%x, expected: 0x%x",
                        be32_to_cpu(fmpl->magic), UBI_FM_POOL_MAGIC);
                goto fail_bad;
        }

        fmpl_wl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
        fm_pos += sizeof(*fmpl_wl);
        if (fm_pos >= fm_size)
                goto fail_bad;
        if (be32_to_cpu(fmpl_wl->magic) != UBI_FM_POOL_MAGIC) {
                ubi_err(ubi, "bad fastmap WL pool magic: 0x%x, expected: 0x%x",
                        be32_to_cpu(fmpl_wl->magic), UBI_FM_POOL_MAGIC);
                goto fail_bad;
        }

        pool_size = be16_to_cpu(fmpl->size);
        wl_pool_size = be16_to_cpu(fmpl_wl->size);
        fm->max_pool_size = be16_to_cpu(fmpl->max_size);
        fm->max_wl_pool_size = be16_to_cpu(fmpl_wl->max_size);

        if (pool_size > UBI_FM_MAX_POOL_SIZE || pool_size < 0) {
                ubi_err(ubi, "bad pool size: %i", pool_size);
                goto fail_bad;
        }

        if (wl_pool_size > UBI_FM_MAX_POOL_SIZE || wl_pool_size < 0) {
                ubi_err(ubi, "bad WL pool size: %i", wl_pool_size);
                goto fail_bad;
        }


        if (fm->max_pool_size > UBI_FM_MAX_POOL_SIZE ||
            fm->max_pool_size < 0) {
                ubi_err(ubi, "bad maximal pool size: %i", fm->max_pool_size);
                goto fail_bad;
        }

        if (fm->max_wl_pool_size > UBI_FM_MAX_POOL_SIZE ||
            fm->max_wl_pool_size < 0) {
                ubi_err(ubi, "bad maximal WL pool size: %i",
                        fm->max_wl_pool_size);
                goto fail_bad;
        }

        /* read EC values from free list */
        for (i = 0; i < be32_to_cpu(fmhdr->free_peb_count); i++) {
                fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
                fm_pos += sizeof(*fmec);
                if (fm_pos >= fm_size)
                        goto fail_bad;

                add_aeb(ai, &ai->free, be32_to_cpu(fmec->pnum),
                        be32_to_cpu(fmec->ec), 0);
        }

        /* read EC values from used list */
        for (i = 0; i < be32_to_cpu(fmhdr->used_peb_count); i++) {
                fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
                fm_pos += sizeof(*fmec);
                if (fm_pos >= fm_size)
                        goto fail_bad;

                add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
                        be32_to_cpu(fmec->ec), 0);
        }

        /* read EC values from scrub list */
        for (i = 0; i < be32_to_cpu(fmhdr->scrub_peb_count); i++) {
                fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
                fm_pos += sizeof(*fmec);
                if (fm_pos >= fm_size)
                        goto fail_bad;

                add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
                        be32_to_cpu(fmec->ec), 1);
        }

        /* read EC values from erase list */
        for (i = 0; i < be32_to_cpu(fmhdr->erase_peb_count); i++) {
                fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
                fm_pos += sizeof(*fmec);
                if (fm_pos >= fm_size)
                        goto fail_bad;

                add_aeb(ai, &ai->erase, be32_to_cpu(fmec->pnum),
                        be32_to_cpu(fmec->ec), 1);
        }

        ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
        ai->bad_peb_count = be32_to_cpu(fmhdr->bad_peb_count);

        /* Iterate over all volumes and read their EBA table */
        for (i = 0; i < be32_to_cpu(fmhdr->vol_count); i++) {
                fmvhdr = (struct ubi_fm_volhdr *)(fm_raw + fm_pos);
                fm_pos += sizeof(*fmvhdr);
                if (fm_pos >= fm_size)
                        goto fail_bad;

                if (be32_to_cpu(fmvhdr->magic) != UBI_FM_VHDR_MAGIC) {
                        ubi_err(ubi, "bad fastmap vol header magic: 0x%x, expected: 0x%x",
                                be32_to_cpu(fmvhdr->magic), UBI_FM_VHDR_MAGIC);
                        goto fail_bad;
                }

                av = add_vol(ai, be32_to_cpu(fmvhdr->vol_id),
                             be32_to_cpu(fmvhdr->used_ebs),
                             be32_to_cpu(fmvhdr->data_pad),
                             fmvhdr->vol_type,
                             be32_to_cpu(fmvhdr->last_eb_bytes));

                if (IS_ERR(av)) {
                        if (PTR_ERR(av) == -EEXIST)
                                ubi_err(ubi, "volume (ID %i) already exists",
                                        fmvhdr->vol_id);

                        goto fail_bad;
                }

                ai->vols_found++;
                if (ai->highest_vol_id < be32_to_cpu(fmvhdr->vol_id))
                        ai->highest_vol_id = be32_to_cpu(fmvhdr->vol_id);

                fm_eba = (struct ubi_fm_eba *)(fm_raw + fm_pos);
                fm_pos += sizeof(*fm_eba);
                fm_pos += (sizeof(__be32) * be32_to_cpu(fm_eba->reserved_pebs));
                if (fm_pos >= fm_size)
                        goto fail_bad;

                if (be32_to_cpu(fm_eba->magic) != UBI_FM_EBA_MAGIC) {
                        ubi_err(ubi, "bad fastmap EBA header magic: 0x%x, expected: 0x%x",
                                be32_to_cpu(fm_eba->magic), UBI_FM_EBA_MAGIC);
                        goto fail_bad;
                }

                for (j = 0; j < be32_to_cpu(fm_eba->reserved_pebs); j++) {
                        int pnum = be32_to_cpu(fm_eba->pnum[j]);

                        if (pnum < 0)
                                continue;

                        aeb = NULL;
                        list_for_each_entry(tmp_aeb, &used, u.list) {
                                if (tmp_aeb->pnum == pnum) {
                                        aeb = tmp_aeb;
                                        break;
                                }
                        }

                        if (!aeb) {
                                ubi_err(ubi, "PEB %i is in EBA but not in used list", pnum);
                                goto fail_bad;
                        }

                        aeb->lnum = j;

                        if (av->highest_lnum <= aeb->lnum)
                                av->highest_lnum = aeb->lnum;

                        assign_aeb_to_av(ai, aeb, av);

                        dbg_bld("inserting PEB:%i (LEB %i) to vol %i",
                                aeb->pnum, aeb->lnum, av->vol_id);
                }
        }

        ret = scan_pool(ubi, ai, fmpl->pebs, pool_size, &max_sqnum, &free);
        if (ret)
                goto fail;

        ret = scan_pool(ubi, ai, fmpl_wl->pebs, wl_pool_size, &max_sqnum, &free);
        if (ret)
                goto fail;

        if (max_sqnum > ai->max_sqnum)
                ai->max_sqnum = max_sqnum;

        list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &free, u.list)
                list_move_tail(&tmp_aeb->u.list, &ai->free);

        list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &used, u.list)
                list_move_tail(&tmp_aeb->u.list, &ai->erase);

        ubi_assert(list_empty(&free));

        /*
         * If fastmap is leaking PEBs (must not happen), raise a
         * fat warning and fall back to scanning mode.
         * We do this here because in ubi_wl_init() it's too late
         * and we cannot fall back to scanning.
         */
        if (WARN_ON(count_fastmap_pebs(ai) != ubi->peb_count -
                    ai->bad_peb_count - fm->used_blocks))
                goto fail_bad;

        return 0;

fail_bad:
        ret = UBI_BAD_FASTMAP;
fail:
        list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &used, u.list) {
                list_del(&tmp_aeb->u.list);
                ubi_free_aeb(ai, tmp_aeb);
        }
        list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &free, u.list) {
                list_del(&tmp_aeb->u.list);
                ubi_free_aeb(ai, tmp_aeb);
        }

        return ret;
}

/**
 * find_fm_anchor - find the most recent Fastmap superblock (anchor)
 * @ai: UBI attach info to be filled
 */
static int find_fm_anchor(struct ubi_attach_info *ai)
{
        int ret = -1;
        struct ubi_ainf_peb *aeb;
        unsigned long long max_sqnum = 0;

        list_for_each_entry(aeb, &ai->fastmap, u.list) {
                if (aeb->vol_id == UBI_FM_SB_VOLUME_ID && aeb->sqnum > max_sqnum) {
                        max_sqnum = aeb->sqnum;
                        ret = aeb->pnum;
                }
        }

        return ret;
}

static struct ubi_ainf_peb *clone_aeb(struct ubi_attach_info *ai,
                                      struct ubi_ainf_peb *old)
{
        struct ubi_ainf_peb *new;

        new = ubi_alloc_aeb(ai, old->pnum, old->ec);
        if (!new)
                return NULL;

        new->vol_id = old->vol_id;
        new->sqnum = old->sqnum;
        new->lnum = old->lnum;
        new->scrub = old->scrub;
        new->copy_flag = old->copy_flag;

        return new;
}

/**
 * ubi_scan_fastmap - scan the fastmap.
 * @ubi: UBI device object
 * @ai: UBI attach info to be filled
 * @scan_ai: UBI attach info from the first 64 PEBs,
 *           used to find the most recent Fastmap data structure
 *
 * Returns 0 on success, UBI_NO_FASTMAP if no fastmap was found,
 * UBI_BAD_FASTMAP if one was found but is not usable.
 * < 0 indicates an internal error.
 */
int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
                     struct ubi_attach_info *scan_ai)
{
        struct ubi_fm_sb *fmsb, *fmsb2;
        struct ubi_vid_io_buf *vb;
        struct ubi_vid_hdr *vh;
        struct ubi_ec_hdr *ech;
        struct ubi_fastmap_layout *fm;
        struct ubi_ainf_peb *aeb;
        int i, used_blocks, pnum, fm_anchor, ret = 0;
        size_t fm_size;
        __be32 crc, tmp_crc;
        unsigned long long sqnum = 0;

        fm_anchor = find_fm_anchor(scan_ai);
        if (fm_anchor < 0)
                return UBI_NO_FASTMAP;

        /* Copy all (possible) fastmap blocks into our new attach structure. */
        list_for_each_entry(aeb, &scan_ai->fastmap, u.list) {
                struct ubi_ainf_peb *new;

                new = clone_aeb(ai, aeb);
                if (!new)
                        return -ENOMEM;

                list_add(&new->u.list, &ai->fastmap);
        }

        down_write(&ubi->fm_protect);
        memset(ubi->fm_buf, 0, ubi->fm_size);

        fmsb = kmalloc(sizeof(*fmsb), GFP_KERNEL);
        if (!fmsb) {
                ret = -ENOMEM;
                goto out;
        }

        fm = kzalloc(sizeof(*fm), GFP_KERNEL);
        if (!fm) {
                ret = -ENOMEM;
                kfree(fmsb);
                goto out;
        }

        ret = ubi_io_read_data(ubi, fmsb, fm_anchor, 0, sizeof(*fmsb));
        if (ret && ret != UBI_IO_BITFLIPS)
                goto free_fm_sb;
        else if (ret == UBI_IO_BITFLIPS)
                fm->to_be_tortured[0] = 1;

        if (be32_to_cpu(fmsb->magic) != UBI_FM_SB_MAGIC) {
                ubi_err(ubi, "bad super block magic: 0x%x, expected: 0x%x",
                        be32_to_cpu(fmsb->magic), UBI_FM_SB_MAGIC);
                ret = UBI_BAD_FASTMAP;
                goto free_fm_sb;
        }

        if (fmsb->version != UBI_FM_FMT_VERSION) {
                ubi_err(ubi, "bad fastmap version: %i, expected: %i",
                        fmsb->version, UBI_FM_FMT_VERSION);
                ret = UBI_BAD_FASTMAP;
                goto free_fm_sb;
        }

        used_blocks = be32_to_cpu(fmsb->used_blocks);
        if (used_blocks > UBI_FM_MAX_BLOCKS || used_blocks < 1) {
                ubi_err(ubi, "number of fastmap blocks is invalid: %i",
                        used_blocks);
                ret = UBI_BAD_FASTMAP;
                goto free_fm_sb;
        }

        fm_size = ubi->leb_size * used_blocks;
        if (fm_size != ubi->fm_size) {
                ubi_err(ubi, "bad fastmap size: %zi, expected: %zi",
                        fm_size, ubi->fm_size);
                ret = UBI_BAD_FASTMAP;
                goto free_fm_sb;
        }

        ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
        if (!ech) {
                ret = -ENOMEM;
                goto free_fm_sb;
        }

        vb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
        if (!vb) {
                ret = -ENOMEM;
                goto free_hdr;
        }

        vh = ubi_get_vid_hdr(vb);

        for (i = 0; i < used_blocks; i++) {
                int image_seq;

                pnum = be32_to_cpu(fmsb->block_loc[i]);

                if (ubi_io_is_bad(ubi, pnum)) {
                        ret = UBI_BAD_FASTMAP;
                        goto free_hdr;
                }

                if (i == 0 && pnum != fm_anchor) {
                        ubi_err(ubi, "Fastmap anchor PEB mismatch: PEB: %i vs. %i",
                                pnum, fm_anchor);
                        ret = UBI_BAD_FASTMAP;
                        goto free_hdr;
                }

                ret = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
                if (ret && ret != UBI_IO_BITFLIPS) {
                        ubi_err(ubi, "unable to read fastmap block# %i EC (PEB: %i)",
                                i, pnum);
                        if (ret > 0)
                                ret = UBI_BAD_FASTMAP;
                        goto free_hdr;
                } else if (ret == UBI_IO_BITFLIPS)
                        fm->to_be_tortured[i] = 1;

                image_seq = be32_to_cpu(ech->image_seq);
                if (!ubi->image_seq)
                        ubi->image_seq = image_seq;

                /*
                 * Older UBI implementations have image_seq set to zero, so
                 * we shouldn't fail if image_seq == 0.
                 */
                if (image_seq && (image_seq != ubi->image_seq)) {
                        ubi_err(ubi, "wrong image seq:%d instead of %d",
                                be32_to_cpu(ech->image_seq), ubi->image_seq);
                        ret = UBI_BAD_FASTMAP;
                        goto free_hdr;
                }

                ret = ubi_io_read_vid_hdr(ubi, pnum, vb, 0);
                if (ret && ret != UBI_IO_BITFLIPS) {
                        ubi_err(ubi, "unable to read fastmap block# %i (PEB: %i)",
                                i, pnum);

                        goto free_hdr;
                }

                if (i == 0) {
                        if (be32_to_cpu(vh->vol_id) != UBI_FM_SB_VOLUME_ID) {
                                ubi_err(ubi, "bad fastmap anchor vol_id: 0x%x, expected: 0x%x",
                                        be32_to_cpu(vh->vol_id),
                                        UBI_FM_SB_VOLUME_ID);
                                ret = UBI_BAD_FASTMAP;
                                goto free_hdr;
                        }
                } else {
                        if (be32_to_cpu(vh->vol_id) != UBI_FM_DATA_VOLUME_ID) {
                                ubi_err(ubi, "bad fastmap data vol_id: 0x%x, expected: 0x%x",
                                        be32_to_cpu(vh->vol_id),
                                        UBI_FM_DATA_VOLUME_ID);
                                ret = UBI_BAD_FASTMAP;
                                goto free_hdr;
                        }
                }

                if (sqnum < be64_to_cpu(vh->sqnum))
                        sqnum = be64_to_cpu(vh->sqnum);

                ret = ubi_io_read_data(ubi, ubi->fm_buf + (ubi->leb_size * i),
                                       pnum, 0, ubi->leb_size);
                if (ret && ret != UBI_IO_BITFLIPS) {
                        ubi_err(ubi, "unable to read fastmap block# %i (PEB: %i, "
                                "err: %i)", i, pnum, ret);
                        goto free_hdr;
                }
        }

        kfree(fmsb);
        fmsb = NULL;

        fmsb2 = (struct ubi_fm_sb *)(ubi->fm_buf);
        tmp_crc = be32_to_cpu(fmsb2->data_crc);
        fmsb2->data_crc = 0;
        crc = crc32(UBI_CRC32_INIT, ubi->fm_buf, fm_size);
        if (crc != tmp_crc) {
                ubi_err(ubi, "fastmap data CRC is invalid");
                ubi_err(ubi, "CRC should be: 0x%x, calc: 0x%x",
                        tmp_crc, crc);
                ret = UBI_BAD_FASTMAP;
                goto free_hdr;
        }

        fmsb2->sqnum = sqnum;

        fm->used_blocks = used_blocks;

        ret = ubi_attach_fastmap(ubi, ai, fm);
        if (ret) {
                if (ret > 0)
                        ret = UBI_BAD_FASTMAP;
                goto free_hdr;
        }

        for (i = 0; i < used_blocks; i++) {
                struct ubi_wl_entry *e;

                e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
                if (!e) {
                        while (i--)
                                kfree(fm->e[i]);

                        ret = -ENOMEM;
                        goto free_hdr;
                }

                e->pnum = be32_to_cpu(fmsb2->block_loc[i]);
                e->ec = be32_to_cpu(fmsb2->block_ec[i]);
                fm->e[i] = e;
        }

        ubi->fm = fm;
        ubi->fm_pool.max_size = ubi->fm->max_pool_size;
        ubi->fm_wl_pool.max_size = ubi->fm->max_wl_pool_size;
        ubi_msg(ubi, "attached by fastmap");
        ubi_msg(ubi, "fastmap pool size: %d", ubi->fm_pool.max_size);
        ubi_msg(ubi, "fastmap WL pool size: %d",
                ubi->fm_wl_pool.max_size);
        ubi->fm_disabled = 0;
        ubi->fast_attach = 1;

        ubi_free_vid_buf(vb);
        kfree(ech);
out:
        up_write(&ubi->fm_protect);
        if (ret == UBI_BAD_FASTMAP)
                ubi_err(ubi, "Attach by fastmap failed, doing a full scan!");
        return ret;

free_hdr:
        ubi_free_vid_buf(vb);
        kfree(ech);
free_fm_sb:
        kfree(fmsb);
        kfree(fm);
        goto out;
}

/**
 * ubi_write_fastmap - writes a fastmap.
 * @ubi: UBI device object
 * @new_fm: the to be written fastmap
 *
 * Returns 0 on success, < 0 indicates an internal error.
 */
static int ubi_write_fastmap(struct ubi_device *ubi,
                             struct ubi_fastmap_layout *new_fm)
{
        size_t fm_pos = 0;
        void *fm_raw;
        struct ubi_fm_sb *fmsb;
        struct ubi_fm_hdr *fmh;
        struct ubi_fm_scan_pool *fmpl, *fmpl_wl;
        struct ubi_fm_ec *fec;
        struct ubi_fm_volhdr *fvh;
        struct ubi_fm_eba *feba;
        struct ubi_wl_entry *wl_e;
        struct ubi_volume *vol;
        struct ubi_vid_io_buf *avbuf, *dvbuf;
        struct ubi_vid_hdr *avhdr, *dvhdr;
        struct ubi_work *ubi_wrk;
        struct rb_node *tmp_rb;
        int ret, i, j, free_peb_count, used_peb_count, vol_count;
        int scrub_peb_count, erase_peb_count;
        unsigned long *seen_pebs = NULL;

        fm_raw = ubi->fm_buf;
        memset(ubi->fm_buf, 0, ubi->fm_size);

        avbuf = new_fm_vbuf(ubi, UBI_FM_SB_VOLUME_ID);
        if (!avbuf) {
                ret = -ENOMEM;
                goto out;
        }

        dvbuf = new_fm_vbuf(ubi, UBI_FM_DATA_VOLUME_ID);
        if (!dvbuf) {
                ret = -ENOMEM;
                goto out_kfree;
        }

        avhdr = ubi_get_vid_hdr(avbuf);
        dvhdr = ubi_get_vid_hdr(dvbuf);

        seen_pebs = init_seen(ubi);
        if (IS_ERR(seen_pebs)) {
                ret = PTR_ERR(seen_pebs);
                goto out_kfree;
        }

        spin_lock(&ubi->volumes_lock);
        spin_lock(&ubi->wl_lock);

        fmsb = (struct ubi_fm_sb *)fm_raw;
        fm_pos += sizeof(*fmsb);
        ubi_assert(fm_pos <= ubi->fm_size);

        fmh = (struct ubi_fm_hdr *)(fm_raw + fm_pos);
        fm_pos += sizeof(*fmh);
        ubi_assert(fm_pos <= ubi->fm_size);

        fmsb->magic = cpu_to_be32(UBI_FM_SB_MAGIC);
        fmsb->version = UBI_FM_FMT_VERSION;
        fmsb->used_blocks = cpu_to_be32(new_fm->used_blocks);
        /* the max sqnum will be filled in while *reading* the fastmap */
        fmsb->sqnum = 0;

        fmh->magic = cpu_to_be32(UBI_FM_HDR_MAGIC);
        free_peb_count = 0;
        used_peb_count = 0;
        scrub_peb_count = 0;
        erase_peb_count = 0;
        vol_count = 0;

        fmpl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
        fm_pos += sizeof(*fmpl);
        fmpl->magic = cpu_to_be32(UBI_FM_POOL_MAGIC);
        fmpl->size = cpu_to_be16(ubi->fm_pool.size);
        fmpl->max_size = cpu_to_be16(ubi->fm_pool.max_size);

        for (i = 0; i < ubi->fm_pool.size; i++) {
                fmpl->pebs[i] = cpu_to_be32(ubi->fm_pool.pebs[i]);
                set_seen(ubi, ubi->fm_pool.pebs[i], seen_pebs);
        }

        fmpl_wl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
        fm_pos += sizeof(*fmpl_wl);
        fmpl_wl->magic = cpu_to_be32(UBI_FM_POOL_MAGIC);
        fmpl_wl->size = cpu_to_be16(ubi->fm_wl_pool.size);
        fmpl_wl->max_size = cpu_to_be16(ubi->fm_wl_pool.max_size);

        for (i = 0; i < ubi->fm_wl_pool.size; i++) {
                fmpl_wl->pebs[i] = cpu_to_be32(ubi->fm_wl_pool.pebs[i]);
                set_seen(ubi, ubi->fm_wl_pool.pebs[i], seen_pebs);
        }

        ubi_for_each_free_peb(ubi, wl_e, tmp_rb) {
                fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);

                fec->pnum = cpu_to_be32(wl_e->pnum);
                set_seen(ubi, wl_e->pnum, seen_pebs);
                fec->ec = cpu_to_be32(wl_e->ec);

                free_peb_count++;
                fm_pos += sizeof(*fec);
                ubi_assert(fm_pos <= ubi->fm_size);
        }
        fmh->free_peb_count = cpu_to_be32(free_peb_count);

        ubi_for_each_used_peb(ubi, wl_e, tmp_rb) {
                fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);

                fec->pnum = cpu_to_be32(wl_e->pnum);
                set_seen(ubi, wl_e->pnum, seen_pebs);
                fec->ec = cpu_to_be32(wl_e->ec);

                used_peb_count++;
                fm_pos += sizeof(*fec);
                ubi_assert(fm_pos <= ubi->fm_size);
        }

        ubi_for_each_protected_peb(ubi, i, wl_e) {
                fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);

                fec->pnum = cpu_to_be32(wl_e->pnum);
                set_seen(ubi, wl_e->pnum, seen_pebs);
                fec->ec = cpu_to_be32(wl_e->ec);

                used_peb_count++;
                fm_pos += sizeof(*fec);
                ubi_assert(fm_pos <= ubi->fm_size);
        }
        fmh->used_peb_count = cpu_to_be32(used_peb_count);

        ubi_for_each_scrub_peb(ubi, wl_e, tmp_rb) {
                fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);

                fec->pnum = cpu_to_be32(wl_e->pnum);
                set_seen(ubi, wl_e->pnum, seen_pebs);
                fec->ec = cpu_to_be32(wl_e->ec);

                scrub_peb_count++;
                fm_pos += sizeof(*fec);
                ubi_assert(fm_pos <= ubi->fm_size);
        }
        fmh->scrub_peb_count = cpu_to_be32(scrub_peb_count);


        list_for_each_entry(ubi_wrk, &ubi->works, list) {
                if (ubi_is_erase_work(ubi_wrk)) {
                        wl_e = ubi_wrk->e;
                        ubi_assert(wl_e);

                        fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);

                        fec->pnum = cpu_to_be32(wl_e->pnum);
                        set_seen(ubi, wl_e->pnum, seen_pebs);
                        fec->ec = cpu_to_be32(wl_e->ec);

                        erase_peb_count++;
                        fm_pos += sizeof(*fec);
                        ubi_assert(fm_pos <= ubi->fm_size);
                }
        }
        fmh->erase_peb_count = cpu_to_be32(erase_peb_count);

        for (i = 0; i < UBI_MAX_VOLUMES + UBI_INT_VOL_COUNT; i++) {
                vol = ubi->volumes[i];

                if (!vol)
                        continue;

                vol_count++;

                fvh = (struct ubi_fm_volhdr *)(fm_raw + fm_pos);
                fm_pos += sizeof(*fvh);
                ubi_assert(fm_pos <= ubi->fm_size);

                fvh->magic = cpu_to_be32(UBI_FM_VHDR_MAGIC);
                fvh->vol_id = cpu_to_be32(vol->vol_id);
                fvh->vol_type = vol->vol_type;
                fvh->used_ebs = cpu_to_be32(vol->used_ebs);
                fvh->data_pad = cpu_to_be32(vol->data_pad);
                fvh->last_eb_bytes = cpu_to_be32(vol->last_eb_bytes);

                ubi_assert(vol->vol_type == UBI_DYNAMIC_VOLUME ||
                        vol->vol_type == UBI_STATIC_VOLUME);

                feba = (struct ubi_fm_eba *)(fm_raw + fm_pos);
                fm_pos += sizeof(*feba) + (sizeof(__be32) * vol->reserved_pebs);
                ubi_assert(fm_pos <= ubi->fm_size);

                for (j = 0; j < vol->reserved_pebs; j++) {
                        struct ubi_eba_leb_desc ldesc;

                        ubi_eba_get_ldesc(vol, j, &ldesc);
                        feba->pnum[j] = cpu_to_be32(ldesc.pnum);
                }

                feba->reserved_pebs = cpu_to_be32(j);
                feba->magic = cpu_to_be32(UBI_FM_EBA_MAGIC);
        }
        fmh->vol_count = cpu_to_be32(vol_count);
        fmh->bad_peb_count = cpu_to_be32(ubi->bad_peb_count);

        avhdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
        avhdr->lnum = 0;

        spin_unlock(&ubi->wl_lock);
        spin_unlock(&ubi->volumes_lock);

        dbg_bld("writing fastmap SB to PEB %i", new_fm->e[0]->pnum);
        ret = ubi_io_write_vid_hdr(ubi, new_fm->e[0]->pnum, avbuf);
        if (ret) {
                ubi_err(ubi, "unable to write vid_hdr to fastmap SB!");
                goto out_kfree;
        }

        for (i = 0; i < new_fm->used_blocks; i++) {
                fmsb->block_loc[i] = cpu_to_be32(new_fm->e[i]->pnum);
                set_seen(ubi, new_fm->e[i]->pnum, seen_pebs);
                fmsb->block_ec[i] = cpu_to_be32(new_fm->e[i]->ec);
        }

        fmsb->data_crc = 0;
        fmsb->data_crc = cpu_to_be32(crc32(UBI_CRC32_INIT, fm_raw,
                                           ubi->fm_size));

        for (i = 1; i < new_fm->used_blocks; i++) {
                dvhdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
                dvhdr->lnum = cpu_to_be32(i);
                dbg_bld("writing fastmap data to PEB %i sqnum %llu",
                        new_fm->e[i]->pnum, be64_to_cpu(dvhdr->sqnum));
                ret = ubi_io_write_vid_hdr(ubi, new_fm->e[i]->pnum, dvbuf);
                if (ret) {
                        ubi_err(ubi, "unable to write vid_hdr to PEB %i!",
                                new_fm->e[i]->pnum);
                        goto out_kfree;
                }
        }

        for (i = 0; i < new_fm->used_blocks; i++) {
                ret = ubi_io_write_data(ubi, fm_raw + (i * ubi->leb_size),
                                        new_fm->e[i]->pnum, 0, ubi->leb_size);
                if (ret) {
                        ubi_err(ubi, "unable to write fastmap to PEB %i!",
                                new_fm->e[i]->pnum);
                        goto out_kfree;
                }
        }

        ubi_assert(new_fm);
        ubi->fm = new_fm;

        ret = self_check_seen(ubi, seen_pebs);
        dbg_bld("fastmap written!");

out_kfree:
        ubi_free_vid_buf(avbuf);
        ubi_free_vid_buf(dvbuf);
        free_seen(seen_pebs);
out:
        return ret;
}

/**
 * erase_block - Manually erase a PEB.
 * @ubi: UBI device object
 * @pnum: PEB to be erased
 *
 * Returns the new EC value on success, < 0 indicates an internal error.
 */
static int erase_block(struct ubi_device *ubi, int pnum)
{
        int ret;
        struct ubi_ec_hdr *ec_hdr;
        long long ec;

        ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
        if (!ec_hdr)
                return -ENOMEM;

        ret = ubi_io_read_ec_hdr(ubi, pnum, ec_hdr, 0);
        if (ret < 0)
                goto out;
        else if (ret && ret != UBI_IO_BITFLIPS) {
                ret = -EINVAL;
                goto out;
        }

        ret = ubi_io_sync_erase(ubi, pnum, 0);
        if (ret < 0)
                goto out;

        ec = be64_to_cpu(ec_hdr->ec);
        ec += ret;
        if (ec > UBI_MAX_ERASECOUNTER) {
                ret = -EINVAL;
                goto out;
        }

        ec_hdr->ec = cpu_to_be64(ec);
        ret = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);
        if (ret < 0)
                goto out;

        ret = ec;
out:
        kfree(ec_hdr);
        return ret;
}

/**
 * invalidate_fastmap - destroys a fastmap.
 * @ubi: UBI device object
 *
 * This function ensures that upon next UBI attach a full scan
 * is issued. We need this if UBI is about to write a new fastmap
 * but is unable to do so. In this case we have two options:
 * a) Make sure that the current fastmap will not be usued upon
 * attach time and contine or b) fall back to RO mode to have the
 * current fastmap in a valid state.
 * Returns 0 on success, < 0 indicates an internal error.
 */
static int invalidate_fastmap(struct ubi_device *ubi)
{
        int ret;
        struct ubi_fastmap_layout *fm;
        struct ubi_wl_entry *e;
        struct ubi_vid_io_buf *vb = NULL;
        struct ubi_vid_hdr *vh;

        if (!ubi->fm)
                return 0;

        ubi->fm = NULL;

        ret = -ENOMEM;
        fm = kzalloc(sizeof(*fm), GFP_KERNEL);
        if (!fm)
                goto out;

        vb = new_fm_vbuf(ubi, UBI_FM_SB_VOLUME_ID);
        if (!vb)
                goto out_free_fm;

        vh = ubi_get_vid_hdr(vb);

        ret = -ENOSPC;
        e = ubi_wl_get_fm_peb(ubi, 1);
        if (!e)
                goto out_free_fm;

        /*
         * Create fake fastmap such that UBI will fall back
         * to scanning mode.
         */
        vh->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
        ret = ubi_io_write_vid_hdr(ubi, e->pnum, vb);
        if (ret < 0) {
                ubi_wl_put_fm_peb(ubi, e, 0, 0);
                goto out_free_fm;
        }

        fm->used_blocks = 1;
        fm->e[0] = e;

        ubi->fm = fm;

out:
        ubi_free_vid_buf(vb);
        return ret;

out_free_fm:
        kfree(fm);
        goto out;
}

/**
 * return_fm_pebs - returns all PEBs used by a fastmap back to the
 * WL sub-system.
 * @ubi: UBI device object
 * @fm: fastmap layout object
 */
static void return_fm_pebs(struct ubi_device *ubi,
                           struct ubi_fastmap_layout *fm)
{
        int i;

        if (!fm)
                return;

        for (i = 0; i < fm->used_blocks; i++) {
                if (fm->e[i]) {
                        ubi_wl_put_fm_peb(ubi, fm->e[i], i,
                                          fm->to_be_tortured[i]);
                        fm->e[i] = NULL;
                }
        }
}

/**
 * ubi_update_fastmap - will be called by UBI if a volume changes or
 * a fastmap pool becomes full.
 * @ubi: UBI device object
 *
 * Returns 0 on success, < 0 indicates an internal error.
 */
int ubi_update_fastmap(struct ubi_device *ubi)
{
        int ret, i, j;
        struct ubi_fastmap_layout *new_fm, *old_fm;
        struct ubi_wl_entry *tmp_e;

        down_write(&ubi->fm_protect);
        down_write(&ubi->work_sem);
        down_write(&ubi->fm_eba_sem);

        ubi_refill_pools(ubi);

        if (ubi->ro_mode || ubi->fm_disabled) {
                up_write(&ubi->fm_eba_sem);
                up_write(&ubi->work_sem);
                up_write(&ubi->fm_protect);
                return 0;
        }

        ret = ubi_ensure_anchor_pebs(ubi);
        if (ret) {
                up_write(&ubi->fm_eba_sem);
                up_write(&ubi->work_sem);
                up_write(&ubi->fm_protect);
                return ret;
        }

        new_fm = kzalloc(sizeof(*new_fm), GFP_KERNEL);
        if (!new_fm) {
                up_write(&ubi->fm_eba_sem);
                up_write(&ubi->work_sem);
                up_write(&ubi->fm_protect);
                return -ENOMEM;
        }

        new_fm->used_blocks = ubi->fm_size / ubi->leb_size;
        old_fm = ubi->fm;
        ubi->fm = NULL;

        if (new_fm->used_blocks > UBI_FM_MAX_BLOCKS) {
                ubi_err(ubi, "fastmap too large");
                ret = -ENOSPC;
                goto err;
        }

        for (i = 1; i < new_fm->used_blocks; i++) {
                spin_lock(&ubi->wl_lock);
                tmp_e = ubi_wl_get_fm_peb(ubi, 0);
                spin_unlock(&ubi->wl_lock);

                if (!tmp_e) {
                        if (old_fm && old_fm->e[i]) {
                                ret = erase_block(ubi, old_fm->e[i]->pnum);
                                if (ret < 0) {
                                        ubi_err(ubi, "could not erase old fastmap PEB");

                                        for (j = 1; j < i; j++) {
                                                ubi_wl_put_fm_peb(ubi, new_fm->e[j],
                                                                  j, 0);
                                                new_fm->e[j] = NULL;
                                        }
                                        goto err;
                                }
                                new_fm->e[i] = old_fm->e[i];
                                old_fm->e[i] = NULL;
                        } else {
                                ubi_err(ubi, "could not get any free erase block");

                                for (j = 1; j < i; j++) {
                                        ubi_wl_put_fm_peb(ubi, new_fm->e[j], j, 0);
                                        new_fm->e[j] = NULL;
                                }

                                ret = -ENOSPC;
                                goto err;
                        }
                } else {
                        new_fm->e[i] = tmp_e;

                        if (old_fm && old_fm->e[i]) {
                                ubi_wl_put_fm_peb(ubi, old_fm->e[i], i,
                                                  old_fm->to_be_tortured[i]);
                                old_fm->e[i] = NULL;
                        }
                }
        }

        /* Old fastmap is larger than the new one */
        if (old_fm && new_fm->used_blocks < old_fm->used_blocks) {
                for (i = new_fm->used_blocks; i < old_fm->used_blocks; i++) {
                        ubi_wl_put_fm_peb(ubi, old_fm->e[i], i,
                                          old_fm->to_be_tortured[i]);
                        old_fm->e[i] = NULL;
                }
        }

        spin_lock(&ubi->wl_lock);
        tmp_e = ubi_wl_get_fm_peb(ubi, 1);
        spin_unlock(&ubi->wl_lock);

        if (old_fm) {
                /* no fresh anchor PEB was found, reuse the old one */
                if (!tmp_e) {
                        ret = erase_block(ubi, old_fm->e[0]->pnum);
                        if (ret < 0) {
                                ubi_err(ubi, "could not erase old anchor PEB");

                                for (i = 1; i < new_fm->used_blocks; i++) {
                                        ubi_wl_put_fm_peb(ubi, new_fm->e[i],
                                                          i, 0);
                                        new_fm->e[i] = NULL;
                                }
                                goto err;
                        }
                        new_fm->e[0] = old_fm->e[0];
                        new_fm->e[0]->ec = ret;
                        old_fm->e[0] = NULL;
                } else {
                        /* we've got a new anchor PEB, return the old one */
                        ubi_wl_put_fm_peb(ubi, old_fm->e[0], 0,
                                          old_fm->to_be_tortured[0]);
                        new_fm->e[0] = tmp_e;
                        old_fm->e[0] = NULL;
                }
        } else {
                if (!tmp_e) {
                        ubi_err(ubi, "could not find any anchor PEB");

                        for (i = 1; i < new_fm->used_blocks; i++) {
                                ubi_wl_put_fm_peb(ubi, new_fm->e[i], i, 0);
                                new_fm->e[i] = NULL;
                        }

                        ret = -ENOSPC;
                        goto err;
                }
                new_fm->e[0] = tmp_e;
        }

        ret = ubi_write_fastmap(ubi, new_fm);

        if (ret)
                goto err;

out_unlock:
        up_write(&ubi->fm_eba_sem);
        up_write(&ubi->work_sem);
        up_write(&ubi->fm_protect);
        kfree(old_fm);
        return ret;

err:
        ubi_warn(ubi, "Unable to write new fastmap, err=%i", ret);

        ret = invalidate_fastmap(ubi);
        if (ret < 0) {
                ubi_err(ubi, "Unable to invalidate current fastmap!");
                ubi_ro_mode(ubi);
        } else {
                return_fm_pebs(ubi, old_fm);
                return_fm_pebs(ubi, new_fm);
                ret = 0;
        }

        kfree(new_fm);
        goto out_unlock;
}