/*
 * Copyright (c) International Business Machines Corp., 2006
 * Copyright (c) Nokia Corporation, 2006
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Author: Artem Bityutskiy (Битюцкий Артём)
 *
 * Jan 2007: Alexander Schmidt, hacked per-volume update.
 */

/*
 * This file contains implementation of the volume update and atomic LEB change
 * functionality.
 *
 * The update operation is based on the per-volume update marker which is
 * stored in the volume table. The update marker is set before the update
 * starts, and removed after the update has been finished. So if the update was
 * interrupted by an unclean re-boot or due to some other reasons, the update
 * marker stays on the flash media and UBI finds it when it attaches the MTD
 * device next time. If the update marker is set for a volume, the volume is
 * treated as damaged and most I/O operations are prohibited. Only a new update
 * operation is allowed.
 *
 * Note, in general it is possible to implement the update operation as a
 * transaction with a roll-back capability.
 */

#include <linux/err.h>
#include <linux/uaccess.h>
#include <linux/math64.h>
#include "ubi.h"

/**
 * set_update_marker - set update marker.
 * @ubi: UBI device description object
 * @vol: volume description object
 *
 * This function sets the update marker flag for volume @vol. Returns zero
 * in case of success and a negative error code in case of failure.
 */
static int set_update_marker(struct ubi_device *ubi, struct ubi_volume *vol)
{
        int err;
        struct ubi_vtbl_record vtbl_rec;

        dbg_gen("set update marker for volume %d", vol->vol_id);

        if (vol->upd_marker) {
                ubi_assert(ubi->vtbl[vol->vol_id].upd_marker);
                dbg_gen("already set");
                return 0;
        }

        memcpy(&vtbl_rec, &ubi->vtbl[vol->vol_id],
               sizeof(struct ubi_vtbl_record));
        vtbl_rec.upd_marker = 1;

        mutex_lock(&ubi->device_mutex);
        err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
        vol->upd_marker = 1;
        mutex_unlock(&ubi->device_mutex);
        return err;
}

/**
 * clear_update_marker - clear update marker.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @bytes: new data size in bytes
 *
 * This function clears the update marker for volume @vol, sets new volume
 * data size and clears the "corrupted" flag (static volumes only). Returns
 * zero in case of success and a negative error code in case of failure.
 */
static int clear_update_marker(struct ubi_device *ubi, struct ubi_volume *vol,
                               long long bytes)
{
        int err;
        struct ubi_vtbl_record vtbl_rec;

        dbg_gen("clear update marker for volume %d", vol->vol_id);

        memcpy(&vtbl_rec, &ubi->vtbl[vol->vol_id],
               sizeof(struct ubi_vtbl_record));
        ubi_assert(vol->upd_marker && vtbl_rec.upd_marker);
        vtbl_rec.upd_marker = 0;

        if (vol->vol_type == UBI_STATIC_VOLUME) {
                vol->corrupted = 0;
                vol->used_bytes = bytes;
                vol->used_ebs = div_u64_rem(bytes, vol->usable_leb_size,
                                            &vol->last_eb_bytes);
                if (vol->last_eb_bytes)
                        vol->used_ebs += 1;
                else
                        vol->last_eb_bytes = vol->usable_leb_size;
        }

        mutex_lock(&ubi->device_mutex);
        err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
        vol->upd_marker = 0;
        mutex_unlock(&ubi->device_mutex);
        return err;
}

/**
 * ubi_start_update - start volume update.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @bytes: update bytes
 *
 * This function starts volume update operation. If @bytes is zero, the volume
 * is just wiped out. Returns zero in case of success and a negative error code
 * in case of failure.
 */
int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
                     long long bytes)
{
        int i, err;

        dbg_gen("start update of volume %d, %llu bytes", vol->vol_id, bytes);
        ubi_assert(!vol->updating && !vol->changing_leb);
        vol->updating = 1;

        err = set_update_marker(ubi, vol);
        if (err)
                return err;

        /* Before updating - wipe out the volume */
        for (i = 0; i < vol->reserved_pebs; i++) {
                err = ubi_eba_unmap_leb(ubi, vol, i);
                if (err)
                        return err;
        }

        if (bytes == 0) {
                err = ubi_wl_flush(ubi);
                if (err)
                        return err;

                err = clear_update_marker(ubi, vol, 0);
                if (err)
                        return err;
                vol->updating = 0;
                return 0;
        }

        vol->upd_buf = vmalloc(ubi->leb_size);
        if (!vol->upd_buf)
                return -ENOMEM;

        vol->upd_ebs = div_u64(bytes + vol->usable_leb_size - 1,
                               vol->usable_leb_size);
        vol->upd_bytes = bytes;
        vol->upd_received = 0;
        return 0;
}

/**
 * ubi_start_leb_change - start atomic LEB change.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @req: operation request
 *
 * This function starts atomic LEB change operation. Returns zero in case of
 * success and a negative error code in case of failure.
 */
int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
                         const struct ubi_leb_change_req *req)
{
        ubi_assert(!vol->updating && !vol->changing_leb);

        dbg_gen("start changing LEB %d:%d, %u bytes",
                vol->vol_id, req->lnum, req->bytes);
        if (req->bytes == 0)
                return ubi_eba_atomic_leb_change(ubi, vol, req->lnum, NULL, 0,
                                                 req->dtype);

        vol->upd_bytes = req->bytes;
        vol->upd_received = 0;
        vol->changing_leb = 1;
        vol->ch_lnum = req->lnum;
        vol->ch_dtype = req->dtype;

        vol->upd_buf = vmalloc(req->bytes);
        if (!vol->upd_buf)
                return -ENOMEM;

        return 0;
}

/**
 * write_leb - write update data.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @lnum: logical eraseblock number
 * @buf: data to write
 * @len: data size
 * @used_ebs: how many logical eraseblocks will this volume contain (static
 * volumes only)
 *
 * This function writes update data to corresponding logical eraseblock. In
 * case of dynamic volume, this function checks if the data contains 0xFF bytes
 * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
 * buffer contains only 0xFF bytes, the LEB is left unmapped.
 *
 * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
 * that we want to make sure that more data may be appended to the logical
 * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
 * this PEB won't be writable anymore. So if one writes the file-system image
 * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
 * space is writable after the update.
 *
 * We do not do this for static volumes because they are read-only. But this
 * also cannot be done because we have to store per-LEB CRC and the correct
 * data length.
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
                     void *buf, int len, int used_ebs)
{
        int err;

        if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
                int l = ALIGN(len, ubi->min_io_size);

                memset(buf + len, 0xFF, l - len);
                len = ubi_calc_data_len(ubi, buf, l);
                if (len == 0) {
                        dbg_gen("all %d bytes contain 0xFF - skip", len);
                        return 0;
                }

                err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len,
                                        UBI_UNKNOWN);
        } else {
                /*
                 * When writing static volume, and this is the last logical
                 * eraseblock, the length (@len) does not have to be aligned to
                 * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
                 * function accepts exact (unaligned) length and stores it in
                 * the VID header. And it takes care of proper alignment by
                 * padding the buffer. Here we just make sure the padding will
                 * contain zeros, not random trash.
                 */
                memset(buf + len, 0, vol->usable_leb_size - len);
                err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len,
                                           UBI_UNKNOWN, used_ebs);
        }

        return err;
}

/**
 * ubi_more_update_data - write more update data.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @buf: write data (user-space memory buffer)
 * @count: how much bytes to write
 *
 * This function writes more data to the volume which is being updated. It may
 * be called arbitrary number of times until all the update data arriveis. This
 * function returns %0 in case of success, number of bytes written during the
 * last call if the whole volume update has been successfully finished, and a
 * negative error code in case of failure.
 */
int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
                         const void __user *buf, int count)
{
        int lnum, offs, err = 0, len, to_write = count;

        dbg_gen("write %d of %lld bytes, %lld already passed",
                count, vol->upd_bytes, vol->upd_received);

        if (ubi->ro_mode)
                return -EROFS;

        lnum = div_u64_rem(vol->upd_received,  vol->usable_leb_size, &offs);
        if (vol->upd_received + count > vol->upd_bytes)
                to_write = count = vol->upd_bytes - vol->upd_received;

        /*
         * When updating volumes, we accumulate whole logical eraseblock of
         * data and write it at once.
         */
        if (offs != 0) {
                /*
                 * This is a write to the middle of the logical eraseblock. We
                 * copy the data to our update buffer and wait for more data or
                 * flush it if the whole eraseblock is written or the update
                 * is finished.
                 */

                len = vol->usable_leb_size - offs;
                if (len > count)
                        len = count;

                err = copy_from_user(vol->upd_buf + offs, buf, len);
                if (err)
                        return -EFAULT;

                if (offs + len == vol->usable_leb_size ||
                    vol->upd_received + len == vol->upd_bytes) {
                        int flush_len = offs + len;

                        /*
                         * OK, we gathered either the whole eraseblock or this
                         * is the last chunk, it's time to flush the buffer.
                         */
                        ubi_assert(flush_len <= vol->usable_leb_size);
                        err = write_leb(ubi, vol, lnum, vol->upd_buf, flush_len,
                                        vol->upd_ebs);
                        if (err)
                                return err;
                }

                vol->upd_received += len;
                count -= len;
                buf += len;
                lnum += 1;
        }

        /*
         * If we've got more to write, let's continue. At this point we know we
         * are starting from the beginning of an eraseblock.
         */
        while (count) {
                if (count > vol->usable_leb_size)
                        len = vol->usable_leb_size;
                else
                        len = count;

                err = copy_from_user(vol->upd_buf, buf, len);
                if (err)
                        return -EFAULT;

                if (len == vol->usable_leb_size ||
                    vol->upd_received + len == vol->upd_bytes) {
                        err = write_leb(ubi, vol, lnum, vol->upd_buf,
                                        len, vol->upd_ebs);
                        if (err)
                                break;
                }

                vol->upd_received += len;
                count -= len;
                lnum += 1;
                buf += len;
        }

        ubi_assert(vol->upd_received <= vol->upd_bytes);
        if (vol->upd_received == vol->upd_bytes) {
                err = ubi_wl_flush(ubi);
                if (err)
                        return err;
                /* The update is finished, clear the update marker */
                err = clear_update_marker(ubi, vol, vol->upd_bytes);
                if (err)
                        return err;
                vol->updating = 0;
                err = to_write;
                vfree(vol->upd_buf);
        }

        return err;
}

/**
 * ubi_more_leb_change_data - accept more data for atomic LEB change.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @buf: write data (user-space memory buffer)
 * @count: how much bytes to write
 *
 * This function accepts more data to the volume which is being under the
 * "atomic LEB change" operation. It may be called arbitrary number of times
 * until all data arrives. This function returns %0 in case of success, number
 * of bytes written during the last call if the whole "atomic LEB change"
 * operation has been successfully finished, and a negative error code in case
 * of failure.
 */
int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
                             const void __user *buf, int count)
{
        int err;

        dbg_gen("write %d of %lld bytes, %lld already passed",
                count, vol->upd_bytes, vol->upd_received);

        if (ubi->ro_mode)
                return -EROFS;

        if (vol->upd_received + count > vol->upd_bytes)
                count = vol->upd_bytes - vol->upd_received;

        err = copy_from_user(vol->upd_buf + vol->upd_received, buf, count);
        if (err)
                return -EFAULT;

        vol->upd_received += count;

        if (vol->upd_received == vol->upd_bytes) {
                int len = ALIGN((int)vol->upd_bytes, ubi->min_io_size);

                memset(vol->upd_buf + vol->upd_bytes, 0xFF,
                       len - vol->upd_bytes);
                len = ubi_calc_data_len(ubi, vol->upd_buf, len);
                err = ubi_eba_atomic_leb_change(ubi, vol, vol->ch_lnum,
                                                vol->upd_buf, len, UBI_UNKNOWN);
                if (err)
                        return err;
        }

        ubi_assert(vol->upd_received <= vol->upd_bytes);
        if (vol->upd_received == vol->upd_bytes) {
                vol->changing_leb = 0;
                err = count;
                vfree(vol->upd_buf);
        }

        return err;
}