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         vol->upd_buf = vmalloc(ubi->leb_size);
 137         if (!vol->upd_buf)
 138                 return -ENOMEM;
 139
 140         err = set_update_marker(ubi, vol);
 141         if (err)
 142                 return err;
 143
 144         /* Before updating - wipe out the volume */
 145         for (i = 0; i < vol->reserved_pebs; i++) {
 146                 err = ubi_eba_unmap_leb(ubi, vol, i);
 147                 if (err)
 148                         return err;
 149         }
 150
 151         err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
 152         if (err)
 153                 return err;
 154
 155         if (bytes == 0) {
 156                 err = clear_update_marker(ubi, vol, 0);
 157                 if (err)
 158                         return err;
 159
 160                 vfree(vol->upd_buf);
 161                 vol->updating = 0;
 162                 return 0;
 163         }
 164
 165         vol->upd_ebs = div_u64(bytes + vol->usable_leb_size - 1,
 166                                vol->usable_leb_size);
 167         vol->upd_bytes = bytes;
 168         vol->upd_received = 0;
 169         return 0;
 170 }
 171
 172 /**
 173  * ubi_start_leb_change - start atomic LEB change.
 174  * @ubi: UBI device description object
 175  * @vol: volume description object
 176  * @req: operation request
 177  *
 178  * This function starts atomic LEB change operation. Returns zero in case of
 179  * success and a negative error code in case of failure.
 180  */
 181 int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
 182                          const struct ubi_leb_change_req *req)
 183 {
 184         ubi_assert(!vol->updating && !vol->changing_leb);
 185
 186         dbg_gen("start changing LEB %d:%d, %u bytes",
 187                 vol->vol_id, req->lnum, req->bytes);
 188         if (req->bytes == 0)
 189                 return ubi_eba_atomic_leb_change(ubi, vol, req->lnum, NULL, 0);
 190
 191         vol->upd_bytes = req->bytes;
 192         vol->upd_received = 0;
 193         vol->changing_leb = 1;
 194         vol->ch_lnum = req->lnum;
 195
 196         vol->upd_buf = vmalloc(ALIGN((int)req->bytes, ubi->min_io_size));
 197         if (!vol->upd_buf)
 198                 return -ENOMEM;
 199
 200         return 0;
 201 }
 202
 203 /**
 204  * write_leb - write update data.
 205  * @ubi: UBI device description object
 206  * @vol: volume description object
 207  * @lnum: logical eraseblock number
 208  * @buf: data to write
 209  * @len: data size
 210  * @used_ebs: how many logical eraseblocks will this volume contain (static
 211  * volumes only)
 212  *
 213  * This function writes update data to corresponding logical eraseblock. In
 214  * case of dynamic volume, this function checks if the data contains 0xFF bytes
 215  * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
 216  * buffer contains only 0xFF bytes, the LEB is left unmapped.
 217  *
 218  * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
 219  * that we want to make sure that more data may be appended to the logical
 220  * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
 221  * this PEB won't be writable anymore. So if one writes the file-system image
 222  * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
 223  * space is writable after the update.
 224  *
 225  * We do not do this for static volumes because they are read-only. But this
 226  * also cannot be done because we have to store per-LEB CRC and the correct
 227  * data length.
 228  *
 229  * This function returns zero in case of success and a negative error code in
 230  * case of failure.
 231  */
 232 static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
 233                      void *buf, int len, int used_ebs)
 234 {
 235         int err;
 236
 237         if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
 238                 int l = ALIGN(len, ubi->min_io_size);
 239
 240                 memset(buf + len, 0xFF, l - len);
 241                 len = ubi_calc_data_len(ubi, buf, l);
 242                 if (len == 0) {
 243                         dbg_gen("all %d bytes contain 0xFF - skip", len);
 244                         return 0;
 245                 }
 246
 247                 err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len);
 248         } else {
 249                 /*
 250                  * When writing static volume, and this is the last logical
 251                  * eraseblock, the length (@len) does not have to be aligned to
 252                  * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
 253                  * function accepts exact (unaligned) length and stores it in
 254                  * the VID header. And it takes care of proper alignment by
 255                  * padding the buffer. Here we just make sure the padding will
 256                  * contain zeros, not random trash.
 257                  */
 258                 memset(buf + len, 0, vol->usable_leb_size - len);
 259                 err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len, used_ebs);
 260         }
 261
 262         return err;
 263 }
 264
 265 /**
 266  * ubi_more_update_data - write more update data.
 267  * @ubi: UBI device description object
 268  * @vol: volume description object
 269  * @buf: write data (user-space memory buffer)
 270  * @count: how much bytes to write
 271  *
 272  * This function writes more data to the volume which is being updated. It may
 273  * be called arbitrary number of times until all the update data arriveis. This
 274  * function returns %0 in case of success, number of bytes written during the
 275  * last call if the whole volume update has been successfully finished, and a
 276  * negative error code in case of failure.
 277  */
 278 int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
 279                          const void __user *buf, int count)
 280 {
 281         int lnum, offs, err = 0, len, to_write = count;
 282
 283         dbg_gen("write %d of %lld bytes, %lld already passed",
 284                 count, vol->upd_bytes, vol->upd_received);
 285
 286         if (ubi->ro_mode)
 287                 return -EROFS;
 288
 289         lnum = div_u64_rem(vol->upd_received,  vol->usable_leb_size, &offs);
 290         if (vol->upd_received + count > vol->upd_bytes)
 291                 to_write = count = vol->upd_bytes - vol->upd_received;
 292
 293         /*
 294          * When updating volumes, we accumulate whole logical eraseblock of
 295          * data and write it at once.
 296          */
 297         if (offs != 0) {
 298                 /*
 299                  * This is a write to the middle of the logical eraseblock. We
 300                  * copy the data to our update buffer and wait for more data or
 301                  * flush it if the whole eraseblock is written or the update
 302                  * is finished.
 303                  */
 304
 305                 len = vol->usable_leb_size - offs;
 306                 if (len > count)
 307                         len = count;
 308
 309                 err = copy_from_user(vol->upd_buf + offs, buf, len);
 310                 if (err)
 311                         return -EFAULT;
 312
 313                 if (offs + len == vol->usable_leb_size ||
 314                     vol->upd_received + len == vol->upd_bytes) {
 315                         int flush_len = offs + len;
 316
 317                         /*
 318                          * OK, we gathered either the whole eraseblock or this
 319                          * is the last chunk, it's time to flush the buffer.
 320                          */
 321                         ubi_assert(flush_len <= vol->usable_leb_size);
 322                         err = write_leb(ubi, vol, lnum, vol->upd_buf, flush_len,
 323                                         vol->upd_ebs);
 324                         if (err)
 325                                 return err;
 326                 }
 327
 328                 vol->upd_received += len;
 329                 count -= len;
 330                 buf += len;
 331                 lnum += 1;
 332         }
 333
 334         /*
 335          * If we've got more to write, let's continue. At this point we know we
 336          * are starting from the beginning of an eraseblock.
 337          */
 338         while (count) {
 339                 if (count > vol->usable_leb_size)
 340                         len = vol->usable_leb_size;
 341                 else
 342                         len = count;
 343
 344                 err = copy_from_user(vol->upd_buf, buf, len);
 345                 if (err)
 346                         return -EFAULT;
 347
 348                 if (len == vol->usable_leb_size ||
 349                     vol->upd_received + len == vol->upd_bytes) {
 350                         err = write_leb(ubi, vol, lnum, vol->upd_buf,
 351                                         len, vol->upd_ebs);
 352                         if (err)
 353                                 break;
 354                 }
 355
 356                 vol->upd_received += len;
 357                 count -= len;
 358                 lnum += 1;
 359                 buf += len;
 360         }
 361
 362         ubi_assert(vol->upd_received <= vol->upd_bytes);
 363         if (vol->upd_received == vol->upd_bytes) {
 364                 err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
 365                 if (err)
 366                         return err;
 367                 /* The update is finished, clear the update marker */
 368                 err = clear_update_marker(ubi, vol, vol->upd_bytes);
 369                 if (err)
 370                         return err;
 371                 vol->updating = 0;
 372                 err = to_write;
 373                 vfree(vol->upd_buf);
 374         }
 375
 376         return err;
 377 }
 378
 379 /**
 380  * ubi_more_leb_change_data - accept more data for atomic LEB change.
 381  * @ubi: UBI device description object
 382  * @vol: volume description object
 383  * @buf: write data (user-space memory buffer)
 384  * @count: how much bytes to write
 385  *
 386  * This function accepts more data to the volume which is being under the
 387  * "atomic LEB change" operation. It may be called arbitrary number of times
 388  * until all data arrives. This function returns %0 in case of success, number
 389  * of bytes written during the last call if the whole "atomic LEB change"
 390  * operation has been successfully finished, and a negative error code in case
 391  * of failure.
 392  */
 393 int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
 394                              const void __user *buf, int count)
 395 {
 396         int err;
 397
 398         dbg_gen("write %d of %lld bytes, %lld already passed",
 399                 count, vol->upd_bytes, vol->upd_received);
 400
 401         if (ubi->ro_mode)
 402                 return -EROFS;
 403
 404         if (vol->upd_received + count > vol->upd_bytes)
 405                 count = vol->upd_bytes - vol->upd_received;
 406
 407         err = copy_from_user(vol->upd_buf + vol->upd_received, buf, count);
 408         if (err)
 409                 return -EFAULT;
 410
 411         vol->upd_received += count;
 412
 413         if (vol->upd_received == vol->upd_bytes) {
 414                 int len = ALIGN((int)vol->upd_bytes, ubi->min_io_size);
 415
 416                 memset(vol->upd_buf + vol->upd_bytes, 0xFF,
 417                        len - vol->upd_bytes);
 418                 len = ubi_calc_data_len(ubi, vol->upd_buf, len);
 419                 err = ubi_eba_atomic_leb_change(ubi, vol, vol->ch_lnum,
 420                                                 vol->upd_buf, len);
 421                 if (err)
 422                         return err;
 423         }
 424
 425         ubi_assert(vol->upd_received <= vol->upd_bytes);
 426         if (vol->upd_received == vol->upd_bytes) {
 427                 vol->changing_leb = 0;
 428                 err = count;
 429                 vfree(vol->upd_buf);
 430         }
 431
 432         return err;
 433 }