drivers/mtd/ubi/cdev.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 /*
  22  * This file includes implementation of UBI character device operations.
  23  *
  24  * There are two kinds of character devices in UBI: UBI character devices and
  25  * UBI volume character devices. UBI character devices allow users to
  26  * manipulate whole volumes: create, remove, and re-size them. Volume character
  27  * devices provide volume I/O capabilities.
  28  *
  29  * Major and minor numbers are assigned dynamically to both UBI and volume
  30  * character devices.
  31  *
  32  * Well, there is the third kind of character devices - the UBI control
  33  * character device, which allows to manipulate by UBI devices - create and
  34  * delete them. In other words, it is used for attaching and detaching MTD
  35  * devices.
  36  */
  37
  38 #include <linux/module.h>
  39 #include <linux/stat.h>
  40 #include <linux/ioctl.h>
  41 #include <linux/capability.h>
  42 #include <linux/smp_lock.h>
  43 #include <mtd/ubi-user.h>
  44 #include <asm/uaccess.h>
  45 #include <asm/div64.h>
  46 #include "ubi.h"
  47
  48 /**
  49  * get_exclusive - get exclusive access to an UBI volume.
  50  * @desc: volume descriptor
  51  *
  52  * This function changes UBI volume open mode to "exclusive". Returns previous
  53  * mode value (positive integer) in case of success and a negative error code
  54  * in case of failure.
  55  */
  56 static int get_exclusive(struct ubi_volume_desc *desc)
  57 {
  58         int users, err;
  59         struct ubi_volume *vol = desc->vol;
  60
  61         spin_lock(&vol->ubi->volumes_lock);
  62         users = vol->readers + vol->writers + vol->exclusive;
  63         ubi_assert(users > 0);
  64         if (users > 1) {
  65                 dbg_err("%d users for volume %d", users, vol->vol_id);
  66                 err = -EBUSY;
  67         } else {
  68                 vol->readers = vol->writers = 0;
  69                 vol->exclusive = 1;
  70                 err = desc->mode;
  71                 desc->mode = UBI_EXCLUSIVE;
  72         }
  73         spin_unlock(&vol->ubi->volumes_lock);
  74
  75         return err;
  76 }
  77
  78 /**
  79  * revoke_exclusive - revoke exclusive mode.
  80  * @desc: volume descriptor
  81  * @mode: new mode to switch to
  82  */
  83 static void revoke_exclusive(struct ubi_volume_desc *desc, int mode)
  84 {
  85         struct ubi_volume *vol = desc->vol;
  86
  87         spin_lock(&vol->ubi->volumes_lock);
  88         ubi_assert(vol->readers == 0 && vol->writers == 0);
  89         ubi_assert(vol->exclusive == 1 && desc->mode == UBI_EXCLUSIVE);
  90         vol->exclusive = 0;
  91         if (mode == UBI_READONLY)
  92                 vol->readers = 1;
  93         else if (mode == UBI_READWRITE)
  94                 vol->writers = 1;
  95         else
  96                 vol->exclusive = 1;
  97         spin_unlock(&vol->ubi->volumes_lock);
  98
  99         desc->mode = mode;
 100 }
 101
 102 static int vol_cdev_open(struct inode *inode, struct file *file)
 103 {
 104         struct ubi_volume_desc *desc;
 105         int vol_id = iminor(inode) - 1, mode, ubi_num;
 106
 107         lock_kernel();
 108         ubi_num = ubi_major2num(imajor(inode));
 109         if (ubi_num < 0) {
 110                 unlock_kernel();
 111                 return ubi_num;
 112         }
 113
 114         if (file->f_mode & FMODE_WRITE)
 115                 mode = UBI_READWRITE;
 116         else
 117                 mode = UBI_READONLY;
 118
 119         dbg_msg("open volume %d, mode %d", vol_id, mode);
 120
 121         desc = ubi_open_volume(ubi_num, vol_id, mode);
 122         unlock_kernel();
 123         if (IS_ERR(desc))
 124                 return PTR_ERR(desc);
 125
 126         file->private_data = desc;
 127         return 0;
 128 }
 129
 130 static int vol_cdev_release(struct inode *inode, struct file *file)
 131 {
 132         struct ubi_volume_desc *desc = file->private_data;
 133         struct ubi_volume *vol = desc->vol;
 134
 135         dbg_msg("release volume %d, mode %d", vol->vol_id, desc->mode);
 136
 137         if (vol->updating) {
 138                 ubi_warn("update of volume %d not finished, volume is damaged",
 139                          vol->vol_id);
 140                 ubi_assert(!vol->changing_leb);
 141                 vol->updating = 0;
 142                 vfree(vol->upd_buf);
 143         } else if (vol->changing_leb) {
 144                 dbg_msg("only %lld of %lld bytes received for atomic LEB change"
 145                         " for volume %d:%d, cancel", vol->upd_received,
 146                         vol->upd_bytes, vol->ubi->ubi_num, vol->vol_id);
 147                 vol->changing_leb = 0;
 148                 vfree(vol->upd_buf);
 149         }
 150
 151         ubi_close_volume(desc);
 152         return 0;
 153 }
 154
 155 static loff_t vol_cdev_llseek(struct file *file, loff_t offset, int origin)
 156 {
 157         struct ubi_volume_desc *desc = file->private_data;
 158         struct ubi_volume *vol = desc->vol;
 159         loff_t new_offset;
 160
 161         if (vol->updating) {
 162                  /* Update is in progress, seeking is prohibited */
 163                 dbg_err("updating");
 164                 return -EBUSY;
 165         }
 166
 167         switch (origin) {
 168         case 0: /* SEEK_SET */
 169                 new_offset = offset;
 170                 break;
 171         case 1: /* SEEK_CUR */
 172                 new_offset = file->f_pos + offset;
 173                 break;
 174         case 2: /* SEEK_END */
 175                 new_offset = vol->used_bytes + offset;
 176                 break;
 177         default:
 178                 return -EINVAL;
 179         }
 180
 181         if (new_offset < 0 || new_offset > vol->used_bytes) {
 182                 dbg_err("bad seek %lld", new_offset);
 183                 return -EINVAL;
 184         }
 185
 186         dbg_msg("seek volume %d, offset %lld, origin %d, new offset %lld",
 187                 vol->vol_id, offset, origin, new_offset);
 188
 189         file->f_pos = new_offset;
 190         return new_offset;
 191 }
 192
 193 static ssize_t vol_cdev_read(struct file *file, __user char *buf, size_t count,
 194                              loff_t *offp)
 195 {
 196         struct ubi_volume_desc *desc = file->private_data;
 197         struct ubi_volume *vol = desc->vol;
 198         struct ubi_device *ubi = vol->ubi;
 199         int err, lnum, off, len,  tbuf_size;
 200         size_t count_save = count;
 201         void *tbuf;
 202         uint64_t tmp;
 203
 204         dbg_msg("read %zd bytes from offset %lld of volume %d",
 205                 count, *offp, vol->vol_id);
 206
 207         if (vol->updating) {
 208                 dbg_err("updating");
 209                 return -EBUSY;
 210         }
 211         if (vol->upd_marker) {
 212                 dbg_err("damaged volume, update marker is set");
 213                 return -EBADF;
 214         }
 215         if (*offp == vol->used_bytes || count == 0)
 216                 return 0;
 217
 218         if (vol->corrupted)
 219                 dbg_msg("read from corrupted volume %d", vol->vol_id);
 220
 221         if (*offp + count > vol->used_bytes)
 222                 count_save = count = vol->used_bytes - *offp;
 223
 224         tbuf_size = vol->usable_leb_size;
 225         if (count < tbuf_size)
 226                 tbuf_size = ALIGN(count, ubi->min_io_size);
 227         tbuf = vmalloc(tbuf_size);
 228         if (!tbuf)
 229                 return -ENOMEM;
 230
 231         len = count > tbuf_size ? tbuf_size : count;
 232
 233         tmp = *offp;
 234         off = do_div(tmp, vol->usable_leb_size);
 235         lnum = tmp;
 236
 237         do {
 238                 cond_resched();
 239
 240                 if (off + len >= vol->usable_leb_size)
 241                         len = vol->usable_leb_size - off;
 242
 243                 err = ubi_eba_read_leb(ubi, vol, lnum, tbuf, off, len, 0);
 244                 if (err)
 245                         break;
 246
 247                 off += len;
 248                 if (off == vol->usable_leb_size) {
 249                         lnum += 1;
 250                         off -= vol->usable_leb_size;
 251                 }
 252
 253                 count -= len;
 254                 *offp += len;
 255
 256                 err = copy_to_user(buf, tbuf, len);
 257                 if (err) {
 258                         err = -EFAULT;
 259                         break;
 260                 }
 261
 262                 buf += len;
 263                 len = count > tbuf_size ? tbuf_size : count;
 264         } while (count);
 265
 266         vfree(tbuf);
 267         return err ? err : count_save - count;
 268 }
 269
 270 #ifdef CONFIG_MTD_UBI_DEBUG_USERSPACE_IO
 271
 272 /*
 273  * This function allows to directly write to dynamic UBI volumes, without
 274  * issuing the volume update operation. Available only as a debugging feature.
 275  * Very useful for testing UBI.
 276  */
 277 static ssize_t vol_cdev_direct_write(struct file *file, const char __user *buf,
 278                                      size_t count, loff_t *offp)
 279 {
 280         struct ubi_volume_desc *desc = file->private_data;
 281         struct ubi_volume *vol = desc->vol;
 282         struct ubi_device *ubi = vol->ubi;
 283         int lnum, off, len, tbuf_size, err = 0;
 284         size_t count_save = count;
 285         char *tbuf;
 286         uint64_t tmp;
 287
 288         dbg_msg("requested: write %zd bytes to offset %lld of volume %u",
 289                 count, *offp, vol->vol_id);
 290
 291         if (vol->vol_type == UBI_STATIC_VOLUME)
 292                 return -EROFS;
 293
 294         tmp = *offp;
 295         off = do_div(tmp, vol->usable_leb_size);
 296         lnum = tmp;
 297
 298         if (off & (ubi->min_io_size - 1)) {
 299                 dbg_err("unaligned position");
 300                 return -EINVAL;
 301         }
 302
 303         if (*offp + count > vol->used_bytes)
 304                 count_save = count = vol->used_bytes - *offp;
 305
 306         /* We can write only in fractions of the minimum I/O unit */
 307         if (count & (ubi->min_io_size - 1)) {
 308                 dbg_err("unaligned write length");
 309                 return -EINVAL;
 310         }
 311
 312         tbuf_size = vol->usable_leb_size;
 313         if (count < tbuf_size)
 314                 tbuf_size = ALIGN(count, ubi->min_io_size);
 315         tbuf = vmalloc(tbuf_size);
 316         if (!tbuf)
 317                 return -ENOMEM;
 318
 319         len = count > tbuf_size ? tbuf_size : count;
 320
 321         while (count) {
 322                 cond_resched();
 323
 324                 if (off + len >= vol->usable_leb_size)
 325                         len = vol->usable_leb_size - off;
 326
 327                 err = copy_from_user(tbuf, buf, len);
 328                 if (err) {
 329                         err = -EFAULT;
 330                         break;
 331                 }
 332
 333                 err = ubi_eba_write_leb(ubi, vol, lnum, tbuf, off, len,
 334                                         UBI_UNKNOWN);
 335                 if (err)
 336                         break;
 337
 338                 off += len;
 339                 if (off == vol->usable_leb_size) {
 340                         lnum += 1;
 341                         off -= vol->usable_leb_size;
 342                 }
 343
 344                 count -= len;
 345                 *offp += len;
 346                 buf += len;
 347                 len = count > tbuf_size ? tbuf_size : count;
 348         }
 349
 350         vfree(tbuf);
 351         return err ? err : count_save - count;
 352 }
 353
 354 #else
 355 #define vol_cdev_direct_write(file, buf, count, offp) -EPERM
 356 #endif /* CONFIG_MTD_UBI_DEBUG_USERSPACE_IO */
 357
 358 static ssize_t vol_cdev_write(struct file *file, const char __user *buf,
 359                               size_t count, loff_t *offp)
 360 {
 361         int err = 0;
 362         struct ubi_volume_desc *desc = file->private_data;
 363         struct ubi_volume *vol = desc->vol;
 364         struct ubi_device *ubi = vol->ubi;
 365
 366         if (!vol->updating && !vol->changing_leb)
 367                 return vol_cdev_direct_write(file, buf, count, offp);
 368
 369         if (vol->updating)
 370                 err = ubi_more_update_data(ubi, vol, buf, count);
 371         else
 372                 err = ubi_more_leb_change_data(ubi, vol, buf, count);
 373
 374         if (err < 0) {
 375                 ubi_err("cannot accept more %zd bytes of data, error %d",
 376                         count, err);
 377                 return err;
 378         }
 379
 380         if (err) {
 381                 /*
 382                  * The operation is finished, @err contains number of actually
 383                  * written bytes.
 384                  */
 385                 count = err;
 386
 387                 if (vol->changing_leb) {
 388                         revoke_exclusive(desc, UBI_READWRITE);
 389                         return count;
 390                 }
 391
 392                 err = ubi_check_volume(ubi, vol->vol_id);
 393                 if (err < 0)
 394                         return err;
 395
 396                 if (err) {
 397                         ubi_warn("volume %d on UBI device %d is corrupted",
 398                                  vol->vol_id, ubi->ubi_num);
 399                         vol->corrupted = 1;
 400                 }
 401                 vol->checked = 1;
 402                 ubi_gluebi_updated(vol);
 403                 revoke_exclusive(desc, UBI_READWRITE);
 404         }
 405
 406         return count;
 407 }
 408
 409 static int vol_cdev_ioctl(struct inode *inode, struct file *file,
 410                           unsigned int cmd, unsigned long arg)
 411 {
 412         int err = 0;
 413         struct ubi_volume_desc *desc = file->private_data;
 414         struct ubi_volume *vol = desc->vol;
 415         struct ubi_device *ubi = vol->ubi;
 416         void __user *argp = (void __user *)arg;
 417
 418         switch (cmd) {
 419         /* Volume update command */
 420         case UBI_IOCVOLUP:
 421         {
 422                 int64_t bytes, rsvd_bytes;
 423
 424                 if (!capable(CAP_SYS_RESOURCE)) {
 425                         err = -EPERM;
 426                         break;
 427                 }
 428
 429                 err = copy_from_user(&bytes, argp, sizeof(int64_t));
 430                 if (err) {
 431                         err = -EFAULT;
 432                         break;
 433                 }
 434
 435                 if (desc->mode == UBI_READONLY) {
 436                         err = -EROFS;
 437                         break;
 438                 }
 439
 440                 rsvd_bytes = (long long)vol->reserved_pebs *
 441                                         ubi->leb_size-vol->data_pad;
 442                 if (bytes < 0 || bytes > rsvd_bytes) {
 443                         err = -EINVAL;
 444                         break;
 445                 }
 446
 447                 err = get_exclusive(desc);
 448                 if (err < 0)
 449                         break;
 450
 451                 err = ubi_start_update(ubi, vol, bytes);
 452                 if (bytes == 0)
 453                         revoke_exclusive(desc, UBI_READWRITE);
 454                 break;
 455         }
 456
 457         /* Atomic logical eraseblock change command */
 458         case UBI_IOCEBCH:
 459         {
 460                 struct ubi_leb_change_req req;
 461
 462                 err = copy_from_user(&req, argp,
 463                                      sizeof(struct ubi_leb_change_req));
 464                 if (err) {
 465                         err = -EFAULT;
 466                         break;
 467                 }
 468
 469                 if (desc->mode == UBI_READONLY ||
 470                     vol->vol_type == UBI_STATIC_VOLUME) {
 471                         err = -EROFS;
 472                         break;
 473                 }
 474
 475                 /* Validate the request */
 476                 err = -EINVAL;
 477                 if (req.lnum < 0 || req.lnum >= vol->reserved_pebs ||
 478                     req.bytes < 0 || req.lnum >= vol->usable_leb_size)
 479                         break;
 480                 if (req.dtype != UBI_LONGTERM && req.dtype != UBI_SHORTTERM &&
 481                     req.dtype != UBI_UNKNOWN)
 482                         break;
 483
 484                 err = get_exclusive(desc);
 485                 if (err < 0)
 486                         break;
 487
 488                 err = ubi_start_leb_change(ubi, vol, &req);
 489                 if (req.bytes == 0)
 490                         revoke_exclusive(desc, UBI_READWRITE);
 491                 break;
 492         }
 493
 494 #ifdef CONFIG_MTD_UBI_DEBUG_USERSPACE_IO
 495         /* Logical eraseblock erasure command */
 496         case UBI_IOCEBER:
 497         {
 498                 int32_t lnum;
 499
 500                 err = get_user(lnum, (__user int32_t *)argp);
 501                 if (err) {
 502                         err = -EFAULT;
 503                         break;
 504                 }
 505
 506                 if (desc->mode == UBI_READONLY ||
 507                     vol->vol_type == UBI_STATIC_VOLUME) {
 508                         err = -EROFS;
 509                         break;
 510                 }
 511
 512                 if (lnum < 0 || lnum >= vol->reserved_pebs) {
 513                         err = -EINVAL;
 514                         break;
 515                 }
 516
 517                 dbg_msg("erase LEB %d:%d", vol->vol_id, lnum);
 518                 err = ubi_eba_unmap_leb(ubi, vol, lnum);
 519                 if (err)
 520                         break;
 521
 522                 err = ubi_wl_flush(ubi);
 523                 break;
 524         }
 525 #endif
 526
 527         default:
 528                 err = -ENOTTY;
 529                 break;
 530         }
 531
 532         return err;
 533 }
 534
 535 /**
 536  * verify_mkvol_req - verify volume creation request.
 537  * @ubi: UBI device description object
 538  * @req: the request to check
 539  *
 540  * This function zero if the request is correct, and %-EINVAL if not.
 541  */
 542 static int verify_mkvol_req(const struct ubi_device *ubi,
 543                             const struct ubi_mkvol_req *req)
 544 {
 545         int n, err = -EINVAL;
 546
 547         if (req->bytes < 0 || req->alignment < 0 || req->vol_type < 0 ||
 548             req->name_len < 0)
 549                 goto bad;
 550
 551         if ((req->vol_id < 0 || req->vol_id >= ubi->vtbl_slots) &&
 552             req->vol_id != UBI_VOL_NUM_AUTO)
 553                 goto bad;
 554
 555         if (req->alignment == 0)
 556                 goto bad;
 557
 558         if (req->bytes == 0)
 559                 goto bad;
 560
 561         if (req->vol_type != UBI_DYNAMIC_VOLUME &&
 562             req->vol_type != UBI_STATIC_VOLUME)
 563                 goto bad;
 564
 565         if (req->alignment > ubi->leb_size)
 566                 goto bad;
 567
 568         n = req->alignment & (ubi->min_io_size - 1);
 569         if (req->alignment != 1 && n)
 570                 goto bad;
 571
 572         if (req->name_len > UBI_VOL_NAME_MAX) {
 573                 err = -ENAMETOOLONG;
 574                 goto bad;
 575         }
 576
 577         return 0;
 578
 579 bad:
 580         dbg_err("bad volume creation request");
 581         ubi_dbg_dump_mkvol_req(req);
 582         return err;
 583 }
 584
 585 /**
 586  * verify_rsvol_req - verify volume re-size request.
 587  * @ubi: UBI device description object
 588  * @req: the request to check
 589  *
 590  * This function returns zero if the request is correct, and %-EINVAL if not.
 591  */
 592 static int verify_rsvol_req(const struct ubi_device *ubi,
 593                             const struct ubi_rsvol_req *req)
 594 {
 595         if (req->bytes <= 0)
 596                 return -EINVAL;
 597
 598         if (req->vol_id < 0 || req->vol_id >= ubi->vtbl_slots)
 599                 return -EINVAL;
 600
 601         return 0;
 602 }
 603
 604 static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
 605                           unsigned int cmd, unsigned long arg)
 606 {
 607         int err = 0;
 608         struct ubi_device *ubi;
 609         struct ubi_volume_desc *desc;
 610         void __user *argp = (void __user *)arg;
 611
 612         if (!capable(CAP_SYS_RESOURCE))
 613                 return -EPERM;
 614
 615         ubi = ubi_get_by_major(imajor(inode));
 616         if (!ubi)
 617                 return -ENODEV;
 618
 619         switch (cmd) {
 620         /* Create volume command */
 621         case UBI_IOCMKVOL:
 622         {
 623                 struct ubi_mkvol_req req;
 624
 625                 dbg_msg("create volume");
 626                 err = copy_from_user(&req, argp, sizeof(struct ubi_mkvol_req));
 627                 if (err) {
 628                         err = -EFAULT;
 629                         break;
 630                 }
 631
 632                 err = verify_mkvol_req(ubi, &req);
 633                 if (err)
 634                         break;
 635
 636                 req.name[req.name_len] = '\0';
 637
 638                 mutex_lock(&ubi->volumes_mutex);
 639                 err = ubi_create_volume(ubi, &req);
 640                 mutex_unlock(&ubi->volumes_mutex);
 641                 if (err)
 642                         break;
 643
 644                 err = put_user(req.vol_id, (__user int32_t *)argp);
 645                 if (err)
 646                         err = -EFAULT;
 647
 648                 break;
 649         }
 650
 651         /* Remove volume command */
 652         case UBI_IOCRMVOL:
 653         {
 654                 int vol_id;
 655
 656                 dbg_msg("remove volume");
 657                 err = get_user(vol_id, (__user int32_t *)argp);
 658                 if (err) {
 659                         err = -EFAULT;
 660                         break;
 661                 }
 662
 663                 desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_EXCLUSIVE);
 664                 if (IS_ERR(desc)) {
 665                         err = PTR_ERR(desc);
 666                         break;
 667                 }
 668
 669                 mutex_lock(&ubi->volumes_mutex);
 670                 err = ubi_remove_volume(desc);
 671                 mutex_unlock(&ubi->volumes_mutex);
 672
 673                 /*
 674                  * The volume is deleted (unless an error occurred), and the
 675                  * 'struct ubi_volume' object will be freed when
 676                  * 'ubi_close_volume()' will call 'put_device()'.
 677                  */
 678                 ubi_close_volume(desc);
 679                 break;
 680         }
 681
 682         /* Re-size volume command */
 683         case UBI_IOCRSVOL:
 684         {
 685                 int pebs;
 686                 uint64_t tmp;
 687                 struct ubi_rsvol_req req;
 688
 689                 dbg_msg("re-size volume");
 690                 err = copy_from_user(&req, argp, sizeof(struct ubi_rsvol_req));
 691                 if (err) {
 692                         err = -EFAULT;
 693                         break;
 694                 }
 695
 696                 err = verify_rsvol_req(ubi, &req);
 697                 if (err)
 698                         break;
 699
 700                 desc = ubi_open_volume(ubi->ubi_num, req.vol_id, UBI_EXCLUSIVE);
 701                 if (IS_ERR(desc)) {
 702                         err = PTR_ERR(desc);
 703                         break;
 704                 }
 705
 706                 tmp = req.bytes;
 707                 pebs = !!do_div(tmp, desc->vol->usable_leb_size);
 708                 pebs += tmp;
 709
 710                 mutex_lock(&ubi->volumes_mutex);
 711                 err = ubi_resize_volume(desc, pebs);
 712                 mutex_unlock(&ubi->volumes_mutex);
 713                 ubi_close_volume(desc);
 714                 break;
 715         }
 716
 717         default:
 718                 err = -ENOTTY;
 719                 break;
 720         }
 721
 722         ubi_put_device(ubi);
 723         return err;
 724 }
 725
 726 static int ctrl_cdev_ioctl(struct inode *inode, struct file *file,
 727                            unsigned int cmd, unsigned long arg)
 728 {
 729         int err = 0;
 730         void __user *argp = (void __user *)arg;
 731
 732         if (!capable(CAP_SYS_RESOURCE))
 733                 return -EPERM;
 734
 735         switch (cmd) {
 736         /* Attach an MTD device command */
 737         case UBI_IOCATT:
 738         {
 739                 struct ubi_attach_req req;
 740                 struct mtd_info *mtd;
 741
 742                 dbg_msg("attach MTD device");
 743                 err = copy_from_user(&req, argp, sizeof(struct ubi_attach_req));
 744                 if (err) {
 745                         err = -EFAULT;
 746                         break;
 747                 }
 748
 749                 if (req.mtd_num < 0 ||
 750                     (req.ubi_num < 0 && req.ubi_num != UBI_DEV_NUM_AUTO)) {
 751                         err = -EINVAL;
 752                         break;
 753                 }
 754
 755                 mtd = get_mtd_device(NULL, req.mtd_num);
 756                 if (IS_ERR(mtd)) {
 757                         err = PTR_ERR(mtd);
 758                         break;
 759                 }
 760
 761                 /*
 762                  * Note, further request verification is done by
 763                  * 'ubi_attach_mtd_dev()'.
 764                  */
 765                 mutex_lock(&ubi_devices_mutex);
 766                 err = ubi_attach_mtd_dev(mtd, req.ubi_num, req.vid_hdr_offset);
 767                 mutex_unlock(&ubi_devices_mutex);
 768                 if (err < 0)
 769                         put_mtd_device(mtd);
 770                 else
 771                         /* @err contains UBI device number */
 772                         err = put_user(err, (__user int32_t *)argp);
 773
 774                 break;
 775         }
 776
 777         /* Detach an MTD device command */
 778         case UBI_IOCDET:
 779         {
 780                 int ubi_num;
 781
 782                 dbg_msg("dettach MTD device");
 783                 err = get_user(ubi_num, (__user int32_t *)argp);
 784                 if (err) {
 785                         err = -EFAULT;
 786                         break;
 787                 }
 788
 789                 mutex_lock(&ubi_devices_mutex);
 790                 err = ubi_detach_mtd_dev(ubi_num, 0);
 791                 mutex_unlock(&ubi_devices_mutex);
 792                 break;
 793         }
 794
 795         default:
 796                 err = -ENOTTY;
 797                 break;
 798         }
 799
 800         return err;
 801 }
 802
 803 /* UBI control character device operations */
 804 struct file_operations ubi_ctrl_cdev_operations = {
 805         .ioctl = ctrl_cdev_ioctl,
 806         .owner = THIS_MODULE,
 807 };
 808
 809 /* UBI character device operations */
 810 struct file_operations ubi_cdev_operations = {
 811         .owner = THIS_MODULE,
 812         .ioctl = ubi_cdev_ioctl,
 813         .llseek = no_llseek,
 814 };
 815
 816 /* UBI volume character device operations */
 817 struct file_operations ubi_vol_cdev_operations = {
 818         .owner   = THIS_MODULE,
 819         .open    = vol_cdev_open,
 820         .release = vol_cdev_release,
 821         .llseek  = vol_cdev_llseek,
 822         .read    = vol_cdev_read,
 823         .write   = vol_cdev_write,
 824         .ioctl   = vol_cdev_ioctl,
 825 };