drivers/mtd/ubi/upd.c

   1 /*
   2  * Copyright (c) International Business Machines Corp., 2006
   3  * Copyright (c) Nokia Corporation, 2006
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  13  * the GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  18  *
  19  * Author: Artem Bityutskiy (Битюцкий Артём)
  20  *
  21  * Jan 2007: Alexander Schmidt, hacked per-volume update.
  22  */
  23
  24 /*
  25  * This file contains implementation of the volume update functionality.
  26  *
  27  * The update operation is based on the per-volume update marker which is
  28  * stored in the volume table. The update marker is set before the update
  29  * starts, and removed after the update has been finished. So if the update was
  30  * interrupted by an unclean re-boot or due to some other reasons, the update
  31  * marker stays on the flash media and UBI finds it when it attaches the MTD
  32  * device next time. If the update marker is set for a volume, the volume is
  33  * treated as damaged and most I/O operations are prohibited. Only a new update
  34  * operation is allowed.
  35  *
  36  * Note, in general it is possible to implement the update operation as a
  37  * transaction with a roll-back capability.
  38  */
  39
  40 #include <linux/err.h>
  41 #include <asm/uaccess.h>
  42 #include <asm/div64.h>
  43 #include "ubi.h"
  44
  45 /**
  46  * set_update_marker - set update marker.
  47  * @ubi: UBI device description object
  48  * @vol: volume description object
  49  *
  50  * This function sets the update marker flag for volume @vol. Returns zero
  51  * in case of success and a negative error code in case of failure.
  52  */
  53 static int set_update_marker(struct ubi_device *ubi, struct ubi_volume *vol)
  54 {
  55         int err;
  56         struct ubi_vtbl_record vtbl_rec;
  57
  58         dbg_msg("set update marker for volume %d", vol->vol_id);
  59
  60         if (vol->upd_marker) {
  61                 ubi_assert(ubi->vtbl[vol->vol_id].upd_marker);
  62                 dbg_msg("already set");
  63                 return 0;
  64         }
  65
  66         memcpy(&vtbl_rec, &ubi->vtbl[vol->vol_id],
  67                sizeof(struct ubi_vtbl_record));
  68         vtbl_rec.upd_marker = 1;
  69
  70         mutex_lock(&ubi->volumes_mutex);
  71         err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
  72         mutex_unlock(&ubi->volumes_mutex);
  73         vol->upd_marker = 1;
  74         return err;
  75 }
  76
  77 /**
  78  * clear_update_marker - clear update marker.
  79  * @ubi: UBI device description object
  80  * @vol: volume description object
  81  * @bytes: new data size in bytes
  82  *
  83  * This function clears the update marker for volume @vol, sets new volume
  84  * data size and clears the "corrupted" flag (static volumes only). Returns
  85  * zero in case of success and a negative error code in case of failure.
  86  */
  87 static int clear_update_marker(struct ubi_device *ubi, struct ubi_volume *vol,
  88                                long long bytes)
  89 {
  90         int err;
  91         uint64_t tmp;
  92         struct ubi_vtbl_record vtbl_rec;
  93
  94         dbg_msg("clear update marker for volume %d", vol->vol_id);
  95
  96         memcpy(&vtbl_rec, &ubi->vtbl[vol->vol_id],
  97                sizeof(struct ubi_vtbl_record));
  98         ubi_assert(vol->upd_marker && vtbl_rec.upd_marker);
  99         vtbl_rec.upd_marker = 0;
 100
 101         if (vol->vol_type == UBI_STATIC_VOLUME) {
 102                 vol->corrupted = 0;
 103                 vol->used_bytes = tmp = bytes;
 104                 vol->last_eb_bytes = do_div(tmp, vol->usable_leb_size);
 105                 vol->used_ebs = tmp;
 106                 if (vol->last_eb_bytes)
 107                         vol->used_ebs += 1;
 108                 else
 109                         vol->last_eb_bytes = vol->usable_leb_size;
 110         }
 111
 112         mutex_lock(&ubi->volumes_mutex);
 113         err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
 114         mutex_unlock(&ubi->volumes_mutex);
 115         vol->upd_marker = 0;
 116         return err;
 117 }
 118
 119 /**
 120  * ubi_start_update - start volume update.
 121  * @ubi: UBI device description object
 122  * @vol: volume description object
 123  * @bytes: update bytes
 124  *
 125  * This function starts volume update operation. If @bytes is zero, the volume
 126  * is just wiped out. Returns zero in case of success and a negative error code
 127  * in case of failure.
 128  */
 129 int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
 130                      long long bytes)
 131 {
 132         int i, err;
 133         uint64_t tmp;
 134
 135         dbg_msg("start update of volume %d, %llu bytes", vol->vol_id, bytes);
 136         vol->updating = 1;
 137
 138         err = set_update_marker(ubi, vol);
 139         if (err)
 140                 return err;
 141
 142         /* Before updating - wipe out the volume */
 143         for (i = 0; i < vol->reserved_pebs; i++) {
 144                 err = ubi_eba_unmap_leb(ubi, vol, i);
 145                 if (err)
 146                         return err;
 147         }
 148
 149         if (bytes == 0) {
 150                 err = clear_update_marker(ubi, vol, 0);
 151                 if (err)
 152                         return err;
 153                 err = ubi_wl_flush(ubi);
 154                 if (!err)
 155                         vol->updating = 0;
 156         }
 157
 158         vol->upd_buf = vmalloc(ubi->leb_size);
 159         if (!vol->upd_buf)
 160                 return -ENOMEM;
 161
 162         tmp = bytes;
 163         vol->upd_ebs = !!do_div(tmp, vol->usable_leb_size);
 164         vol->upd_ebs += tmp;
 165         vol->upd_bytes = bytes;
 166         vol->upd_received = 0;
 167         return 0;
 168 }
 169
 170 /**
 171  * write_leb - write update data.
 172  * @ubi: UBI device description object
 173  * @vol: volume description object
 174  * @lnum: logical eraseblock number
 175  * @buf: data to write
 176  * @len: data size
 177  * @used_ebs: how many logical eraseblocks will this volume contain (static
 178  * volumes only)
 179  *
 180  * This function writes update data to corresponding logical eraseblock. In
 181  * case of dynamic volume, this function checks if the data contains 0xFF bytes
 182  * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
 183  * buffer contains only 0xFF bytes, the LEB is left unmapped.
 184  *
 185  * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
 186  * that we want to make sure that more data may be appended to the logical
 187  * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
 188  * this PEB won't be writable anymore. So if one writes the file-system image
 189  * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
 190  * space is writable after the update.
 191  *
 192  * We do not do this for static volumes because they are read-only. But this
 193  * also cannot be done because we have to store per-LEB CRC and the correct
 194  * data length.
 195  *
 196  * This function returns zero in case of success and a negative error code in
 197  * case of failure.
 198  */
 199 static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
 200                      void *buf, int len, int used_ebs)
 201 {
 202         int err, l;
 203
 204         if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
 205                 l = ALIGN(len, ubi->min_io_size);
 206                 memset(buf + len, 0xFF, l - len);
 207
 208                 l = ubi_calc_data_len(ubi, buf, l);
 209                 if (l == 0) {
 210                         dbg_msg("all %d bytes contain 0xFF - skip", len);
 211                         return 0;
 212                 }
 213                 if (len != l)
 214                         dbg_msg("skip last %d bytes (0xFF)", len - l);
 215
 216                 err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, l, UBI_UNKNOWN);
 217         } else {
 218                 /*
 219                  * When writing static volume, and this is the last logical
 220                  * eraseblock, the length (@len) does not have to be aligned to
 221                  * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
 222                  * function accepts exact (unaligned) length and stores it in
 223                  * the VID header. And it takes care of proper alignment by
 224                  * padding the buffer. Here we just make sure the padding will
 225                  * contain zeros, not random trash.
 226                  */
 227                 memset(buf + len, 0, vol->usable_leb_size - len);
 228                 err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len,
 229                                            UBI_UNKNOWN, used_ebs);
 230         }
 231
 232         return err;
 233 }
 234
 235 /**
 236  * ubi_more_update_data - write more update data.
 237  * @vol: volume description object
 238  * @buf: write data (user-space memory buffer)
 239  * @count: how much bytes to write
 240  *
 241  * This function writes more data to the volume which is being updated. It may
 242  * be called arbitrary number of times until all of the update data arrive.
 243  * This function returns %0 in case of success, number of bytes written during
 244  * the last call if the whole volume update was successfully finished, and a
 245  * negative error code in case of failure.
 246  */
 247 int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
 248                          const void __user *buf, int count)
 249 {
 250         uint64_t tmp;
 251         int lnum, offs, err = 0, len, to_write = count;
 252
 253         dbg_msg("write %d of %lld bytes, %lld already passed",
 254                 count, vol->upd_bytes, vol->upd_received);
 255
 256         if (ubi->ro_mode)
 257                 return -EROFS;
 258
 259         tmp = vol->upd_received;
 260         offs = do_div(tmp, vol->usable_leb_size);
 261         lnum = tmp;
 262
 263         if (vol->upd_received + count > vol->upd_bytes)
 264                 to_write = count = vol->upd_bytes - vol->upd_received;
 265
 266         /*
 267          * When updating volumes, we accumulate whole logical eraseblock of
 268          * data and write it at once.
 269          */
 270         if (offs != 0) {
 271                 /*
 272                  * This is a write to the middle of the logical eraseblock. We
 273                  * copy the data to our update buffer and wait for more data or
 274                  * flush it if the whole eraseblock is written or the update
 275                  * is finished.
 276                  */
 277
 278                 len = vol->usable_leb_size - offs;
 279                 if (len > count)
 280                         len = count;
 281
 282                 err = copy_from_user(vol->upd_buf + offs, buf, len);
 283                 if (err)
 284                         return -EFAULT;
 285
 286                 if (offs + len == vol->usable_leb_size ||
 287                     vol->upd_received + len == vol->upd_bytes) {
 288                         int flush_len = offs + len;
 289
 290                         /*
 291                          * OK, we gathered either the whole eraseblock or this
 292                          * is the last chunk, it's time to flush the buffer.
 293                          */
 294                         ubi_assert(flush_len <= vol->usable_leb_size);
 295                         err = write_leb(ubi, vol, lnum, vol->upd_buf, flush_len,
 296                                         vol->upd_ebs);
 297                         if (err)
 298                                 return err;
 299                 }
 300
 301                 vol->upd_received += len;
 302                 count -= len;
 303                 buf += len;
 304                 lnum += 1;
 305         }
 306
 307         /*
 308          * If we've got more to write, let's continue. At this point we know we
 309          * are starting from the beginning of an eraseblock.
 310          */
 311         while (count) {
 312                 if (count > vol->usable_leb_size)
 313                         len = vol->usable_leb_size;
 314                 else
 315                         len = count;
 316
 317                 err = copy_from_user(vol->upd_buf, buf, len);
 318                 if (err)
 319                         return -EFAULT;
 320
 321                 if (len == vol->usable_leb_size ||
 322                     vol->upd_received + len == vol->upd_bytes) {
 323                         err = write_leb(ubi, vol, lnum, vol->upd_buf,
 324                                         len, vol->upd_ebs);
 325                         if (err)
 326                                 break;
 327                 }
 328
 329                 vol->upd_received += len;
 330                 count -= len;
 331                 lnum += 1;
 332                 buf += len;
 333         }
 334
 335         ubi_assert(vol->upd_received <= vol->upd_bytes);
 336         if (vol->upd_received == vol->upd_bytes) {
 337                 /* The update is finished, clear the update marker */
 338                 err = clear_update_marker(ubi, vol, vol->upd_bytes);
 339                 if (err)
 340                         return err;
 341                 err = ubi_wl_flush(ubi);
 342                 if (err == 0) {
 343                         err = to_write;
 344                         vfree(vol->upd_buf);
 345                 }
 346         }
 347
 348         return err;
 349 }