upd.c

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/*
 * 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"

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;
}

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;
}

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, UBI_ALL, UBI_ALL);
        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;
}

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);

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

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

    return 0;
}

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);
    } 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, used_ebs);
    }

    return err;
}

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, UBI_ALL, UBI_ALL);
        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;
}

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);
        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;
}