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 and atomic LEB change
  26  * functionality.
  27  *
  28  * The update operation is based on the per-volume update marker which is
  29  * stored in the volume table. The update marker is set before the update
  30  * starts, and removed after the update has been finished. So if the update was
  31  * interrupted by an unclean re-boot or due to some other reasons, the update
  32  * marker stays on the flash media and UBI finds it when it attaches the MTD
  33  * device next time. If the update marker is set for a volume, the volume is
  34  * treated as damaged and most I/O operations are prohibited. Only a new update
  35  * operation is allowed.
  36  *
  37  * Note, in general it is possible to implement the update operation as a
  38  * transaction with a roll-back capability.
  39  */
  40
  41 #include <linux/err.h>
  42 #include <linux/uaccess.h>
  43 #include <linux/math64.h>
  44 #include "ubi.h"
  45
  46 /**
  47  * set_update_marker - set update marker.
  48  * @ubi: UBI device description object
  49  * @vol: volume description object
  50  *
  51  * This function sets the update marker flag for volume @vol. Returns zero
  52  * in case of success and a negative error code in case of failure.
  53  */
  54 static int set_update_marker(struct ubi_device *ubi, struct ubi_volume *vol)
  55 {
  56         int err;
  57         struct ubi_vtbl_record vtbl_rec;
  58
  59         dbg_gen("set update marker for volume %d", vol->vol_id);
  60
  61         if (vol->upd_marker) {
  62                 ubi_assert(ubi->vtbl[vol->vol_id].upd_marker);
  63                 dbg_gen("already set");
  64                 return 0;
  65         }
  66
  67         vtbl_rec = ubi->vtbl[vol->vol_id];
  68         vtbl_rec.upd_marker = 1;
  69
  70         mutex_lock(&ubi->device_mutex);
  71         err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
  72         vol->upd_marker = 1;
  73         mutex_unlock(&ubi->device_mutex);
  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         struct ubi_vtbl_record vtbl_rec;
  92
  93         dbg_gen("clear update marker for volume %d", vol->vol_id);
  94
  95         vtbl_rec = ubi->vtbl[vol->vol_id];
  96         ubi_assert(vol->upd_marker && vtbl_rec.upd_marker);
  97         vtbl_rec.upd_marker = 0;
  98
  99         if (vol->vol_type == UBI_STATIC_VOLUME) {
 100                 vol->corrupted = 0;
 101                 vol->used_bytes = bytes;
 102                 vol->used_ebs = div_u64_rem(bytes, vol->usable_leb_size,
 103                                             &vol->last_eb_bytes);
 104                 if (vol->last_eb_bytes)
 105                         vol->used_ebs += 1;
 106                 else
 107                         vol->last_eb_bytes = vol->usable_leb_size;
 108         }
 109
 110         mutex_lock(&ubi->device_mutex);
 111         err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
 112         vol->upd_marker = 0;
 113         mutex_unlock(&ubi->device_mutex);
 114         return err;
 115 }
 116
 117 /**
 118  * ubi_start_update - start volume update.
 119  * @ubi: UBI device description object
 120  * @vol: volume description object
 121  * @bytes: update bytes
 122  *
 123  * This function starts volume update operation. If @bytes is zero, the volume
 124  * is just wiped out. Returns zero in case of success and a negative error code
 125  * in case of failure.
 126  */
 127 int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
 128                      long long bytes)
 129 {
 130         int i, err;
 131
 132         dbg_gen("start update of volume %d, %llu bytes", vol->vol_id, bytes);
 133         ubi_assert(!vol->updating && !vol->changing_leb);
 134         vol->updating = 1;
 135
 136         err = set_update_marker(ubi, vol);
 137         if (err)
 138                 return err;
 139
 140         /* Before updating - wipe out the volume */
 141         for (i = 0; i < vol->reserved_pebs; i++) {
 142                 err = ubi_eba_unmap_leb(ubi, vol, i);
 143                 if (err)
 144                         return err;
 145         }
 146
 147         if (bytes == 0) {
 148                 err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
 149                 if (err)
 150                         return err;
 151
 152                 err = clear_update_marker(ubi, vol, 0);
 153                 if (err)
 154                         return err;
 155                 vol->updating = 0;
 156                 return 0;
 157         }
 158
 159         vol->upd_buf = kmalloc(ubi->leb_size, GFP_KERNEL);
 160         if (!vol->upd_buf)
 161                 return -ENOMEM;
 162
 163         vol->upd_ebs = div_u64(bytes + vol->usable_leb_size - 1,
 164                                vol->usable_leb_size);
 165         vol->upd_bytes = bytes;
 166         vol->upd_received = 0;
 167         return 0;
 168 }
 169
 170 /**
 171  * ubi_start_leb_change - start atomic LEB change.
 172  * @ubi: UBI device description object
 173  * @vol: volume description object
 174  * @req: operation request
 175  *
 176  * This function starts atomic LEB change operation. Returns zero in case of
 177  * success and a negative error code in case of failure.
 178  */
 179 int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
 180                          const struct ubi_leb_change_req *req)
 181 {
 182         ubi_assert(!vol->updating && !vol->changing_leb);
 183
 184         dbg_gen("start changing LEB %d:%d, %u bytes",
 185                 vol->vol_id, req->lnum, req->bytes);
 186         if (req->bytes == 0)
 187                 return ubi_eba_atomic_leb_change(ubi, vol, req->lnum, NULL, 0);
 188
 189         vol->upd_bytes = req->bytes;
 190         vol->upd_received = 0;
 191         vol->changing_leb = 1;
 192         vol->ch_lnum = req->lnum;
 193
 194         vol->upd_buf = kmalloc(req->bytes, GFP_KERNEL);
 195         if (!vol->upd_buf)
 196                 return -ENOMEM;
 197
 198         return 0;
 199 }
 200
 201 /**
 202  * write_leb - write update data.
 203  * @ubi: UBI device description object
 204  * @vol: volume description object
 205  * @lnum: logical eraseblock number
 206  * @buf: data to write
 207  * @len: data size
 208  * @used_ebs: how many logical eraseblocks will this volume contain (static
 209  * volumes only)
 210  *
 211  * This function writes update data to corresponding logical eraseblock. In
 212  * case of dynamic volume, this function checks if the data contains 0xFF bytes
 213  * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
 214  * buffer contains only 0xFF bytes, the LEB is left unmapped.
 215  *
 216  * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
 217  * that we want to make sure that more data may be appended to the logical
 218  * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
 219  * this PEB won't be writable anymore. So if one writes the file-system image
 220  * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
 221  * space is writable after the update.
 222  *
 223  * We do not do this for static volumes because they are read-only. But this
 224  * also cannot be done because we have to store per-LEB CRC and the correct
 225  * data length.
 226  *
 227  * This function returns zero in case of success and a negative error code in
 228  * case of failure.
 229  */
 230 static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
 231                      void *buf, int len, int used_ebs)
 232 {
 233         int err;
 234
 235         if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
 236                 int l = ALIGN(len, ubi->min_io_size);
 237
 238                 memset(buf + len, 0xFF, l - len);
 239                 len = ubi_calc_data_len(ubi, buf, l);
 240                 if (len == 0) {
 241                         dbg_gen("all %d bytes contain 0xFF - skip", len);
 242                         return 0;
 243                 }
 244
 245                 err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len);
 246         } else {
 247                 /*
 248                  * When writing static volume, and this is the last logical
 249                  * eraseblock, the length (@len) does not have to be aligned to
 250                  * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
 251                  * function accepts exact (unaligned) length and stores it in
 252                  * the VID header. And it takes care of proper alignment by
 253                  * padding the buffer. Here we just make sure the padding will
 254                  * contain zeros, not random trash.
 255                  */
 256                 memset(buf + len, 0, vol->usable_leb_size - len);
 257                 err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len, used_ebs);
 258         }
 259
 260         return err;
 261 }
 262
 263 /**
 264  * ubi_more_update_data - write more update data.
 265  * @ubi: UBI device description object
 266  * @vol: volume description object
 267  * @buf: write data (user-space memory buffer)
 268  * @count: how much bytes to write
 269  *
 270  * This function writes more data to the volume which is being updated. It may
 271  * be called arbitrary number of times until all the update data arriveis. This
 272  * function returns %0 in case of success, number of bytes written during the
 273  * last call if the whole volume update has been successfully finished, and a
 274  * negative error code in case of failure.
 275  */
 276 int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
 277                          const void __user *buf, int count)
 278 {
 279         int lnum, offs, err = 0, len, to_write = count;
 280
 281         dbg_gen("write %d of %lld bytes, %lld already passed",
 282                 count, vol->upd_bytes, vol->upd_received);
 283
 284         if (ubi->ro_mode)
 285                 return -EROFS;
 286
 287         lnum = div_u64_rem(vol->upd_received,  vol->usable_leb_size, &offs);
 288         if (vol->upd_received + count > vol->upd_bytes)
 289                 to_write = count = vol->upd_bytes - vol->upd_received;
 290
 291         /*
 292          * When updating volumes, we accumulate whole logical eraseblock of
 293          * data and write it at once.
 294          */
 295         if (offs != 0) {
 296                 /*
 297                  * This is a write to the middle of the logical eraseblock. We
 298                  * copy the data to our update buffer and wait for more data or
 299                  * flush it if the whole eraseblock is written or the update
 300                  * is finished.
 301                  */
 302
 303                 len = vol->usable_leb_size - offs;
 304                 if (len > count)
 305                         len = count;
 306
 307                 err = copy_from_user(vol->upd_buf + offs, buf, len);
 308                 if (err)
 309                         return -EFAULT;
 310
 311                 if (offs + len == vol->usable_leb_size ||
 312                     vol->upd_received + len == vol->upd_bytes) {
 313                         int flush_len = offs + len;
 314
 315                         /*
 316                          * OK, we gathered either the whole eraseblock or this
 317                          * is the last chunk, it's time to flush the buffer.
 318                          */
 319                         ubi_assert(flush_len <= vol->usable_leb_size);
 320                         err = write_leb(ubi, vol, lnum, vol->upd_buf, flush_len,
 321                                         vol->upd_ebs);
 322                         if (err)
 323                                 return err;
 324                 }
 325
 326                 vol->upd_received += len;
 327                 count -= len;
 328                 buf += len;
 329                 lnum += 1;
 330         }
 331
 332         /*
 333          * If we've got more to write, let's continue. At this point we know we
 334          * are starting from the beginning of an eraseblock.
 335          */
 336         while (count) {
 337                 if (count > vol->usable_leb_size)
 338                         len = vol->usable_leb_size;
 339                 else
 340                         len = count;
 341
 342                 err = copy_from_user(vol->upd_buf, buf, len);
 343                 if (err)
 344                         return -EFAULT;
 345
 346                 if (len == vol->usable_leb_size ||
 347                     vol->upd_received + len == vol->upd_bytes) {
 348                         err = write_leb(ubi, vol, lnum, vol->upd_buf,
 349                                         len, vol->upd_ebs);
 350                         if (err)
 351                                 break;
 352                 }
 353
 354                 vol->upd_received += len;
 355                 count -= len;
 356                 lnum += 1;
 357                 buf += len;
 358         }
 359
 360         ubi_assert(vol->upd_received <= vol->upd_bytes);
 361         if (vol->upd_received == vol->upd_bytes) {
 362                 err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
 363                 if (err)
 364                         return err;
 365                 /* The update is finished, clear the update marker */
 366                 err = clear_update_marker(ubi, vol, vol->upd_bytes);
 367                 if (err)
 368                         return err;
 369                 vol->updating = 0;
 370                 err = to_write;
 371                 kfree(vol->upd_buf);
 372         }
 373
 374         return err;
 375 }
 376
 377 /**
 378  * ubi_more_leb_change_data - accept more data for atomic LEB change.
 379  * @ubi: UBI device description object
 380  * @vol: volume description object
 381  * @buf: write data (user-space memory buffer)
 382  * @count: how much bytes to write
 383  *
 384  * This function accepts more data to the volume which is being under the
 385  * "atomic LEB change" operation. It may be called arbitrary number of times
 386  * until all data arrives. This function returns %0 in case of success, number
 387  * of bytes written during the last call if the whole "atomic LEB change"
 388  * operation has been successfully finished, and a negative error code in case
 389  * of failure.
 390  */
 391 int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
 392                              const void __user *buf, int count)
 393 {
 394         int err;
 395
 396         dbg_gen("write %d of %lld bytes, %lld already passed",
 397                 count, vol->upd_bytes, vol->upd_received);
 398
 399         if (ubi->ro_mode)
 400                 return -EROFS;
 401
 402         if (vol->upd_received + count > vol->upd_bytes)
 403                 count = vol->upd_bytes - vol->upd_received;
 404
 405         err = copy_from_user(vol->upd_buf + vol->upd_received, buf, count);
 406         if (err)
 407                 return -EFAULT;
 408
 409         vol->upd_received += count;
 410
 411         if (vol->upd_received == vol->upd_bytes) {
 412                 int len = ALIGN((int)vol->upd_bytes, ubi->min_io_size);
 413
 414                 memset(vol->upd_buf + vol->upd_bytes, 0xFF,
 415                        len - vol->upd_bytes);
 416                 len = ubi_calc_data_len(ubi, vol->upd_buf, len);
 417                 err = ubi_eba_atomic_leb_change(ubi, vol, vol->ch_lnum,
 418                                                 vol->upd_buf, len);
 419                 if (err)
 420                         return err;
 421         }
 422
 423         ubi_assert(vol->upd_received <= vol->upd_bytes);
 424         if (vol->upd_received == vol->upd_bytes) {
 425                 vol->changing_leb = 0;
 426                 err = count;
 427                 kfree(vol->upd_buf);
 428         }
 429
 430         return err;
 431 }