drivers/mtd/ubi/kapi.c

   1 /*
   2  * Copyright (c) International Business Machines Corp., 2006
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  12  * the GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  17  *
  18  * Author: Artem Bityutskiy (Битюцкий Артём)
  19  */
  20
  21 /* This file mostly implements UBI kernel API functions */
  22
  23 #include <linux/module.h>
  24 #include <linux/err.h>
  25 #include <asm/div64.h>
  26 #include "ubi.h"
  27
  28 /**
  29  * ubi_get_device_info - get information about UBI device.
  30  * @ubi_num: UBI device number
  31  * @di: the information is stored here
  32  *
  33  * This function returns %0 in case of success, %-EINVAL if the UBI device
  34  * number is invalid, and %-ENODEV if there is no such UBI device.
  35  */
  36 int ubi_get_device_info(int ubi_num, struct ubi_device_info *di)
  37 {
  38         struct ubi_device *ubi;
  39
  40         if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
  41                 return -EINVAL;
  42
  43         ubi = ubi_get_device(ubi_num);
  44         if (!ubi)
  45                 return -ENODEV;
  46
  47         di->ubi_num = ubi->ubi_num;
  48         di->leb_size = ubi->leb_size;
  49         di->min_io_size = ubi->min_io_size;
  50         di->ro_mode = ubi->ro_mode;
  51         di->cdev = ubi->cdev.dev;
  52
  53         ubi_put_device(ubi);
  54         return 0;
  55 }
  56 EXPORT_SYMBOL_GPL(ubi_get_device_info);
  57
  58 /**
  59  * ubi_get_volume_info - get information about UBI volume.
  60  * @desc: volume descriptor
  61  * @vi: the information is stored here
  62  */
  63 void ubi_get_volume_info(struct ubi_volume_desc *desc,
  64                          struct ubi_volume_info *vi)
  65 {
  66         const struct ubi_volume *vol = desc->vol;
  67         const struct ubi_device *ubi = vol->ubi;
  68
  69         vi->vol_id = vol->vol_id;
  70         vi->ubi_num = ubi->ubi_num;
  71         vi->size = vol->reserved_pebs;
  72         vi->used_bytes = vol->used_bytes;
  73         vi->vol_type = vol->vol_type;
  74         vi->corrupted = vol->corrupted;
  75         vi->upd_marker = vol->upd_marker;
  76         vi->alignment = vol->alignment;
  77         vi->usable_leb_size = vol->usable_leb_size;
  78         vi->name_len = vol->name_len;
  79         vi->name = vol->name;
  80         vi->cdev = vol->cdev.dev;
  81 }
  82 EXPORT_SYMBOL_GPL(ubi_get_volume_info);
  83
  84 /**
  85  * ubi_open_volume - open UBI volume.
  86  * @ubi_num: UBI device number
  87  * @vol_id: volume ID
  88  * @mode: open mode
  89  *
  90  * The @mode parameter specifies if the volume should be opened in read-only
  91  * mode, read-write mode, or exclusive mode. The exclusive mode guarantees that
  92  * nobody else will be able to open this volume. UBI allows to have many volume
  93  * readers and one writer at a time.
  94  *
  95  * If a static volume is being opened for the first time since boot, it will be
  96  * checked by this function, which means it will be fully read and the CRC
  97  * checksum of each logical eraseblock will be checked.
  98  *
  99  * This function returns volume descriptor in case of success and a negative
 100  * error code in case of failure.
 101  */
 102 struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
 103 {
 104         int err;
 105         struct ubi_volume_desc *desc;
 106         struct ubi_device *ubi;
 107         struct ubi_volume *vol;
 108
 109         dbg_msg("open device %d volume %d, mode %d", ubi_num, vol_id, mode);
 110
 111         if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
 112                 return ERR_PTR(-EINVAL);
 113
 114         if (mode != UBI_READONLY && mode != UBI_READWRITE &&
 115             mode != UBI_EXCLUSIVE)
 116                 return ERR_PTR(-EINVAL);
 117
 118         /*
 119          * First of all, we have to get the UBI device to prevent its removal.
 120          */
 121         ubi = ubi_get_device(ubi_num);
 122         if (!ubi)
 123                 return ERR_PTR(-ENODEV);
 124
 125         if (vol_id < 0 || vol_id >= ubi->vtbl_slots) {
 126                 err = -EINVAL;
 127                 goto out_put_ubi;
 128         }
 129
 130         desc = kmalloc(sizeof(struct ubi_volume_desc), GFP_KERNEL);
 131         if (!desc) {
 132                 err = -ENOMEM;
 133                 goto out_put_ubi;
 134         }
 135
 136         err = -ENODEV;
 137         if (!try_module_get(THIS_MODULE))
 138                 goto out_free;
 139
 140         spin_lock(&ubi->volumes_lock);
 141         vol = ubi->volumes[vol_id];
 142         if (!vol)
 143                 goto out_unlock;
 144
 145         err = -EBUSY;
 146         switch (mode) {
 147         case UBI_READONLY:
 148                 if (vol->exclusive)
 149                         goto out_unlock;
 150                 vol->readers += 1;
 151                 break;
 152
 153         case UBI_READWRITE:
 154                 if (vol->exclusive || vol->writers > 0)
 155                         goto out_unlock;
 156                 vol->writers += 1;
 157                 break;
 158
 159         case UBI_EXCLUSIVE:
 160                 if (vol->exclusive || vol->writers || vol->readers)
 161                         goto out_unlock;
 162                 vol->exclusive = 1;
 163                 break;
 164         }
 165         get_device(&vol->dev);
 166         vol->ref_count += 1;
 167         spin_unlock(&ubi->volumes_lock);
 168
 169         desc->vol = vol;
 170         desc->mode = mode;
 171
 172         mutex_lock(&ubi->ckvol_mutex);
 173         if (!vol->checked) {
 174                 /* This is the first open - check the volume */
 175                 err = ubi_check_volume(ubi, vol_id);
 176                 if (err < 0) {
 177                         mutex_unlock(&ubi->ckvol_mutex);
 178                         ubi_close_volume(desc);
 179                         return ERR_PTR(err);
 180                 }
 181                 if (err == 1) {
 182                         ubi_warn("volume %d on UBI device %d is corrupted",
 183                                  vol_id, ubi->ubi_num);
 184                         vol->corrupted = 1;
 185                 }
 186                 vol->checked = 1;
 187         }
 188         mutex_unlock(&ubi->ckvol_mutex);
 189
 190         return desc;
 191
 192 out_unlock:
 193         spin_unlock(&ubi->volumes_lock);
 194         module_put(THIS_MODULE);
 195 out_free:
 196         kfree(desc);
 197 out_put_ubi:
 198         ubi_put_device(ubi);
 199         return ERR_PTR(err);
 200 }
 201 EXPORT_SYMBOL_GPL(ubi_open_volume);
 202
 203 /**
 204  * ubi_open_volume_nm - open UBI volume by name.
 205  * @ubi_num: UBI device number
 206  * @name: volume name
 207  * @mode: open mode
 208  *
 209  * This function is similar to 'ubi_open_volume()', but opens a volume by name.
 210  */
 211 struct ubi_volume_desc *ubi_open_volume_nm(int ubi_num, const char *name,
 212                                            int mode)
 213 {
 214         int i, vol_id = -1, len;
 215         struct ubi_device *ubi;
 216         struct ubi_volume_desc *ret;
 217
 218         dbg_msg("open volume %s, mode %d", name, mode);
 219
 220         if (!name)
 221                 return ERR_PTR(-EINVAL);
 222
 223         len = strnlen(name, UBI_VOL_NAME_MAX + 1);
 224         if (len > UBI_VOL_NAME_MAX)
 225                 return ERR_PTR(-EINVAL);
 226
 227         if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
 228                 return ERR_PTR(-EINVAL);
 229
 230         ubi = ubi_get_device(ubi_num);
 231         if (!ubi)
 232                 return ERR_PTR(-ENODEV);
 233
 234         spin_lock(&ubi->volumes_lock);
 235         /* Walk all volumes of this UBI device */
 236         for (i = 0; i < ubi->vtbl_slots; i++) {
 237                 struct ubi_volume *vol = ubi->volumes[i];
 238
 239                 if (vol && len == vol->name_len && !strcmp(name, vol->name)) {
 240                         vol_id = i;
 241                         break;
 242                 }
 243         }
 244         spin_unlock(&ubi->volumes_lock);
 245
 246         if (vol_id >= 0)
 247                 ret = ubi_open_volume(ubi_num, vol_id, mode);
 248         else
 249                 ret = ERR_PTR(-ENODEV);
 250
 251         /*
 252          * We should put the UBI device even in case of success, because
 253          * 'ubi_open_volume()' took a reference as well.
 254          */
 255         ubi_put_device(ubi);
 256         return ret;
 257 }
 258 EXPORT_SYMBOL_GPL(ubi_open_volume_nm);
 259
 260 /**
 261  * ubi_close_volume - close UBI volume.
 262  * @desc: volume descriptor
 263  */
 264 void ubi_close_volume(struct ubi_volume_desc *desc)
 265 {
 266         struct ubi_volume *vol = desc->vol;
 267         struct ubi_device *ubi = vol->ubi;
 268
 269         dbg_msg("close volume %d, mode %d", vol->vol_id, desc->mode);
 270
 271         spin_lock(&ubi->volumes_lock);
 272         switch (desc->mode) {
 273         case UBI_READONLY:
 274                 vol->readers -= 1;
 275                 break;
 276         case UBI_READWRITE:
 277                 vol->writers -= 1;
 278                 break;
 279         case UBI_EXCLUSIVE:
 280                 vol->exclusive = 0;
 281         }
 282         vol->ref_count -= 1;
 283         spin_unlock(&ubi->volumes_lock);
 284
 285         kfree(desc);
 286         put_device(&vol->dev);
 287         ubi_put_device(ubi);
 288         module_put(THIS_MODULE);
 289 }
 290 EXPORT_SYMBOL_GPL(ubi_close_volume);
 291
 292 /**
 293  * ubi_leb_read - read data.
 294  * @desc: volume descriptor
 295  * @lnum: logical eraseblock number to read from
 296  * @buf: buffer where to store the read data
 297  * @offset: offset within the logical eraseblock to read from
 298  * @len: how many bytes to read
 299  * @check: whether UBI has to check the read data's CRC or not.
 300  *
 301  * This function reads data from offset @offset of logical eraseblock @lnum and
 302  * stores the data at @buf. When reading from static volumes, @check specifies
 303  * whether the data has to be checked or not. If yes, the whole logical
 304  * eraseblock will be read and its CRC checksum will be checked (i.e., the CRC
 305  * checksum is per-eraseblock). So checking may substantially slow down the
 306  * read speed. The @check argument is ignored for dynamic volumes.
 307  *
 308  * In case of success, this function returns zero. In case of failure, this
 309  * function returns a negative error code.
 310  *
 311  * %-EBADMSG error code is returned:
 312  * o for both static and dynamic volumes if MTD driver has detected a data
 313  *   integrity problem (unrecoverable ECC checksum mismatch in case of NAND);
 314  * o for static volumes in case of data CRC mismatch.
 315  *
 316  * If the volume is damaged because of an interrupted update this function just
 317  * returns immediately with %-EBADF error code.
 318  */
 319 int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
 320                  int len, int check)
 321 {
 322         struct ubi_volume *vol = desc->vol;
 323         struct ubi_device *ubi = vol->ubi;
 324         int err, vol_id = vol->vol_id;
 325
 326         dbg_msg("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
 327
 328         if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
 329             lnum >= vol->used_ebs || offset < 0 || len < 0 ||
 330             offset + len > vol->usable_leb_size)
 331                 return -EINVAL;
 332
 333         if (vol->vol_type == UBI_STATIC_VOLUME) {
 334                 if (vol->used_ebs == 0)
 335                         /* Empty static UBI volume */
 336                         return 0;
 337                 if (lnum == vol->used_ebs - 1 &&
 338                     offset + len > vol->last_eb_bytes)
 339                         return -EINVAL;
 340         }
 341
 342         if (vol->upd_marker)
 343                 return -EBADF;
 344         if (len == 0)
 345                 return 0;
 346
 347         err = ubi_eba_read_leb(ubi, vol, lnum, buf, offset, len, check);
 348         if (err && err == -EBADMSG && vol->vol_type == UBI_STATIC_VOLUME) {
 349                 ubi_warn("mark volume %d as corrupted", vol_id);
 350                 vol->corrupted = 1;
 351         }
 352
 353         return err;
 354 }
 355 EXPORT_SYMBOL_GPL(ubi_leb_read);
 356
 357 /**
 358  * ubi_leb_write - write data.
 359  * @desc: volume descriptor
 360  * @lnum: logical eraseblock number to write to
 361  * @buf: data to write
 362  * @offset: offset within the logical eraseblock where to write
 363  * @len: how many bytes to write
 364  * @dtype: expected data type
 365  *
 366  * This function writes @len bytes of data from @buf to offset @offset of
 367  * logical eraseblock @lnum. The @dtype argument describes expected lifetime of
 368  * the data.
 369  *
 370  * This function takes care of physical eraseblock write failures. If write to
 371  * the physical eraseblock write operation fails, the logical eraseblock is
 372  * re-mapped to another physical eraseblock, the data is recovered, and the
 373  * write finishes. UBI has a pool of reserved physical eraseblocks for this.
 374  *
 375  * If all the data were successfully written, zero is returned. If an error
 376  * occurred and UBI has not been able to recover from it, this function returns
 377  * a negative error code. Note, in case of an error, it is possible that
 378  * something was still written to the flash media, but that may be some
 379  * garbage.
 380  *
 381  * If the volume is damaged because of an interrupted update this function just
 382  * returns immediately with %-EBADF code.
 383  */
 384 int ubi_leb_write(struct ubi_volume_desc *desc, int lnum, const void *buf,
 385                   int offset, int len, int dtype)
 386 {
 387         struct ubi_volume *vol = desc->vol;
 388         struct ubi_device *ubi = vol->ubi;
 389         int vol_id = vol->vol_id;
 390
 391         dbg_msg("write %d bytes to LEB %d:%d:%d", len, vol_id, lnum, offset);
 392
 393         if (vol_id < 0 || vol_id >= ubi->vtbl_slots)
 394                 return -EINVAL;
 395
 396         if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
 397                 return -EROFS;
 398
 399         if (lnum < 0 || lnum >= vol->reserved_pebs || offset < 0 || len < 0 ||
 400             offset + len > vol->usable_leb_size || offset % ubi->min_io_size ||
 401             len % ubi->min_io_size)
 402                 return -EINVAL;
 403
 404         if (dtype != UBI_LONGTERM && dtype != UBI_SHORTTERM &&
 405             dtype != UBI_UNKNOWN)
 406                 return -EINVAL;
 407
 408         if (vol->upd_marker)
 409                 return -EBADF;
 410
 411         if (len == 0)
 412                 return 0;
 413
 414         return ubi_eba_write_leb(ubi, vol, lnum, buf, offset, len, dtype);
 415 }
 416 EXPORT_SYMBOL_GPL(ubi_leb_write);
 417
 418 /*
 419  * ubi_leb_change - change logical eraseblock atomically.
 420  * @desc: volume descriptor
 421  * @lnum: logical eraseblock number to change
 422  * @buf: data to write
 423  * @len: how many bytes to write
 424  * @dtype: expected data type
 425  *
 426  * This function changes the contents of a logical eraseblock atomically. @buf
 427  * has to contain new logical eraseblock data, and @len - the length of the
 428  * data, which has to be aligned. The length may be shorter then the logical
 429  * eraseblock size, ant the logical eraseblock may be appended to more times
 430  * later on. This function guarantees that in case of an unclean reboot the old
 431  * contents is preserved. Returns zero in case of success and a negative error
 432  * code in case of failure.
 433  */
 434 int ubi_leb_change(struct ubi_volume_desc *desc, int lnum, const void *buf,
 435                    int len, int dtype)
 436 {
 437         struct ubi_volume *vol = desc->vol;
 438         struct ubi_device *ubi = vol->ubi;
 439         int vol_id = vol->vol_id;
 440
 441         dbg_msg("atomically write %d bytes to LEB %d:%d", len, vol_id, lnum);
 442
 443         if (vol_id < 0 || vol_id >= ubi->vtbl_slots)
 444                 return -EINVAL;
 445
 446         if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
 447                 return -EROFS;
 448
 449         if (lnum < 0 || lnum >= vol->reserved_pebs || len < 0 ||
 450             len > vol->usable_leb_size || len % ubi->min_io_size)
 451                 return -EINVAL;
 452
 453         if (dtype != UBI_LONGTERM && dtype != UBI_SHORTTERM &&
 454             dtype != UBI_UNKNOWN)
 455                 return -EINVAL;
 456
 457         if (vol->upd_marker)
 458                 return -EBADF;
 459
 460         if (len == 0)
 461                 return 0;
 462
 463         return ubi_eba_atomic_leb_change(ubi, vol, lnum, buf, len, dtype);
 464 }
 465 EXPORT_SYMBOL_GPL(ubi_leb_change);
 466
 467 /**
 468  * ubi_leb_erase - erase logical eraseblock.
 469  * @desc: volume descriptor
 470  * @lnum: logical eraseblock number
 471  *
 472  * This function un-maps logical eraseblock @lnum and synchronously erases the
 473  * correspondent physical eraseblock. Returns zero in case of success and a
 474  * negative error code in case of failure.
 475  *
 476  * If the volume is damaged because of an interrupted update this function just
 477  * returns immediately with %-EBADF code.
 478  */
 479 int ubi_leb_erase(struct ubi_volume_desc *desc, int lnum)
 480 {
 481         struct ubi_volume *vol = desc->vol;
 482         struct ubi_device *ubi = vol->ubi;
 483         int err;
 484
 485         dbg_msg("erase LEB %d:%d", vol->vol_id, lnum);
 486
 487         if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
 488                 return -EROFS;
 489
 490         if (lnum < 0 || lnum >= vol->reserved_pebs)
 491                 return -EINVAL;
 492
 493         if (vol->upd_marker)
 494                 return -EBADF;
 495
 496         err = ubi_eba_unmap_leb(ubi, vol, lnum);
 497         if (err)
 498                 return err;
 499
 500         return ubi_wl_flush(ubi);
 501 }
 502 EXPORT_SYMBOL_GPL(ubi_leb_erase);
 503
 504 /**
 505  * ubi_leb_unmap - un-map logical eraseblock.
 506  * @desc: volume descriptor
 507  * @lnum: logical eraseblock number
 508  *
 509  * This function un-maps logical eraseblock @lnum and schedules the
 510  * corresponding physical eraseblock for erasure, so that it will eventually be
 511  * physically erased in background. This operation is much faster then the
 512  * erase operation.
 513  *
 514  * Unlike erase, the un-map operation does not guarantee that the logical
 515  * eraseblock will contain all 0xFF bytes when UBI is initialized again. For
 516  * example, if several logical eraseblocks are un-mapped, and an unclean reboot
 517  * happens after this, the logical eraseblocks will not necessarily be
 518  * un-mapped again when this MTD device is attached. They may actually be
 519  * mapped to the same physical eraseblocks again. So, this function has to be
 520  * used with care.
 521  *
 522  * In other words, when un-mapping a logical eraseblock, UBI does not store
 523  * any information about this on the flash media, it just marks the logical
 524  * eraseblock as "un-mapped" in RAM. If UBI is detached before the physical
 525  * eraseblock is physically erased, it will be mapped again to the same logical
 526  * eraseblock when the MTD device is attached again.
 527  *
 528  * The main and obvious use-case of this function is when the contents of a
 529  * logical eraseblock has to be re-written. Then it is much more efficient to
 530  * first un-map it, then write new data, rather then first erase it, then write
 531  * new data. Note, once new data has been written to the logical eraseblock,
 532  * UBI guarantees that the old contents has gone forever. In other words, if an
 533  * unclean reboot happens after the logical eraseblock has been un-mapped and
 534  * then written to, it will contain the last written data.
 535  *
 536  * This function returns zero in case of success and a negative error code in
 537  * case of failure. If the volume is damaged because of an interrupted update
 538  * this function just returns immediately with %-EBADF code.
 539  */
 540 int ubi_leb_unmap(struct ubi_volume_desc *desc, int lnum)
 541 {
 542         struct ubi_volume *vol = desc->vol;
 543         struct ubi_device *ubi = vol->ubi;
 544
 545         dbg_msg("unmap LEB %d:%d", vol->vol_id, lnum);
 546
 547         if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
 548                 return -EROFS;
 549
 550         if (lnum < 0 || lnum >= vol->reserved_pebs)
 551                 return -EINVAL;
 552
 553         if (vol->upd_marker)
 554                 return -EBADF;
 555
 556         return ubi_eba_unmap_leb(ubi, vol, lnum);
 557 }
 558 EXPORT_SYMBOL_GPL(ubi_leb_unmap);
 559
 560 /**
 561  * ubi_leb_map - map logical erasblock to a physical eraseblock.
 562  * @desc: volume descriptor
 563  * @lnum: logical eraseblock number
 564  * @dtype: expected data type
 565  *
 566  * This function maps an un-mapped logical eraseblock @lnum to a physical
 567  * eraseblock. This means, that after a successfull invocation of this
 568  * function the logical eraseblock @lnum will be empty (contain only %0xFF
 569  * bytes) and be mapped to a physical eraseblock, even if an unclean reboot
 570  * happens.
 571  *
 572  * This function returns zero in case of success, %-EBADF if the volume is
 573  * damaged because of an interrupted update, %-EBADMSG if the logical
 574  * eraseblock is already mapped, and other negative error codes in case of
 575  * other failures.
 576  */
 577 int ubi_leb_map(struct ubi_volume_desc *desc, int lnum, int dtype)
 578 {
 579         struct ubi_volume *vol = desc->vol;
 580         struct ubi_device *ubi = vol->ubi;
 581
 582         dbg_msg("unmap LEB %d:%d", vol->vol_id, lnum);
 583
 584         if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
 585                 return -EROFS;
 586
 587         if (lnum < 0 || lnum >= vol->reserved_pebs)
 588                 return -EINVAL;
 589
 590         if (dtype != UBI_LONGTERM && dtype != UBI_SHORTTERM &&
 591             dtype != UBI_UNKNOWN)
 592                 return -EINVAL;
 593
 594         if (vol->upd_marker)
 595                 return -EBADF;
 596
 597         if (vol->eba_tbl[lnum] >= 0)
 598                 return -EBADMSG;
 599
 600         return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0, dtype);
 601 }
 602 EXPORT_SYMBOL_GPL(ubi_leb_map);
 603
 604 /**
 605  * ubi_is_mapped - check if logical eraseblock is mapped.
 606  * @desc: volume descriptor
 607  * @lnum: logical eraseblock number
 608  *
 609  * This function checks if logical eraseblock @lnum is mapped to a physical
 610  * eraseblock. If a logical eraseblock is un-mapped, this does not necessarily
 611  * mean it will still be un-mapped after the UBI device is re-attached. The
 612  * logical eraseblock may become mapped to the physical eraseblock it was last
 613  * mapped to.
 614  *
 615  * This function returns %1 if the LEB is mapped, %0 if not, and a negative
 616  * error code in case of failure. If the volume is damaged because of an
 617  * interrupted update this function just returns immediately with %-EBADF error
 618  * code.
 619  */
 620 int ubi_is_mapped(struct ubi_volume_desc *desc, int lnum)
 621 {
 622         struct ubi_volume *vol = desc->vol;
 623
 624         dbg_msg("test LEB %d:%d", vol->vol_id, lnum);
 625
 626         if (lnum < 0 || lnum >= vol->reserved_pebs)
 627                 return -EINVAL;
 628
 629         if (vol->upd_marker)
 630                 return -EBADF;
 631
 632         return vol->eba_tbl[lnum] >= 0;
 633 }
 634 EXPORT_SYMBOL_GPL(ubi_is_mapped);