root/drivers/s390/block/dasd_ioctl.c

DEFINITIONS

1. dasd_ioctl_api_version
2. dasd_ioctl_enable
3. dasd_ioctl_disable
4. dasd_ioctl_quiesce
5. dasd_ioctl_resume
6. dasd_ioctl_abortio
7. dasd_ioctl_allowio
8. dasd_format
9. dasd_check_format
10. dasd_ioctl_format
11. dasd_ioctl_check_format
12. dasd_release_space
13. dasd_ioctl_release_space
14. dasd_ioctl_reset_profile
15. dasd_ioctl_read_profile
16. dasd_ioctl_reset_profile
17. dasd_ioctl_read_profile
18. dasd_ioctl_information
19. dasd_ioctl_set_ro
20. dasd_ioctl_readall_cmb
21. dasd_ioctl

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Author(s)......: Holger Smolinski <Holger.Smolinski@de.ibm.com>
   4  *                  Horst Hummel <Horst.Hummel@de.ibm.com>
   5  *                  Carsten Otte <Cotte@de.ibm.com>
   6  *                  Martin Schwidefsky <schwidefsky@de.ibm.com>
   7  * Bugreports.to..: <Linux390@de.ibm.com>
   8  * Copyright IBM Corp. 1999, 2001
   9  *
  10  * i/o controls for the dasd driver.
  11  */
  12 
  13 #define KMSG_COMPONENT "dasd"
  14 
  15 #include <linux/interrupt.h>
  16 #include <linux/compat.h>
  17 #include <linux/major.h>
  18 #include <linux/fs.h>
  19 #include <linux/blkpg.h>
  20 #include <linux/slab.h>
  21 #include <asm/ccwdev.h>
  22 #include <asm/schid.h>
  23 #include <asm/cmb.h>
  24 #include <linux/uaccess.h>
  25 
  26 /* This is ugly... */
  27 #define PRINTK_HEADER "dasd_ioctl:"
  28 
  29 #include "dasd_int.h"
  30 
  31 
  32 static int
  33 dasd_ioctl_api_version(void __user *argp)
  34 {
  35         int ver = DASD_API_VERSION;
  36         return put_user(ver, (int __user *)argp);
  37 }
  38 
  39 /*
  40  * Enable device.
  41  * used by dasdfmt after BIODASDDISABLE to retrigger blocksize detection
  42  */
  43 static int
  44 dasd_ioctl_enable(struct block_device *bdev)
  45 {
  46         struct dasd_device *base;
  47 
  48         if (!capable(CAP_SYS_ADMIN))
  49                 return -EACCES;
  50 
  51         base = dasd_device_from_gendisk(bdev->bd_disk);
  52         if (!base)
  53                 return -ENODEV;
  54 
  55         dasd_enable_device(base);
  56         /* Formatting the dasd device can change the capacity. */
  57         mutex_lock(&bdev->bd_mutex);
  58         i_size_write(bdev->bd_inode,
  59                      (loff_t)get_capacity(base->block->gdp) << 9);
  60         mutex_unlock(&bdev->bd_mutex);
  61         dasd_put_device(base);
  62         return 0;
  63 }
  64 
  65 /*
  66  * Disable device.
  67  * Used by dasdfmt. Disable I/O operations but allow ioctls.
  68  */
  69 static int
  70 dasd_ioctl_disable(struct block_device *bdev)
  71 {
  72         struct dasd_device *base;
  73 
  74         if (!capable(CAP_SYS_ADMIN))
  75                 return -EACCES;
  76 
  77         base = dasd_device_from_gendisk(bdev->bd_disk);
  78         if (!base)
  79                 return -ENODEV;
  80         /*
  81          * Man this is sick. We don't do a real disable but only downgrade
  82          * the device to DASD_STATE_BASIC. The reason is that dasdfmt uses
  83          * BIODASDDISABLE to disable accesses to the device via the block
  84          * device layer but it still wants to do i/o on the device by
  85          * using the BIODASDFMT ioctl. Therefore the correct state for the
  86          * device is DASD_STATE_BASIC that allows to do basic i/o.
  87          */
  88         dasd_set_target_state(base, DASD_STATE_BASIC);
  89         /*
  90          * Set i_size to zero, since read, write, etc. check against this
  91          * value.
  92          */
  93         mutex_lock(&bdev->bd_mutex);
  94         i_size_write(bdev->bd_inode, 0);
  95         mutex_unlock(&bdev->bd_mutex);
  96         dasd_put_device(base);
  97         return 0;
  98 }
  99 
 100 /*
 101  * Quiesce device.
 102  */
 103 static int dasd_ioctl_quiesce(struct dasd_block *block)
 104 {
 105         unsigned long flags;
 106         struct dasd_device *base;
 107 
 108         base = block->base;
 109         if (!capable (CAP_SYS_ADMIN))
 110                 return -EACCES;
 111 
 112         pr_info("%s: The DASD has been put in the quiesce "
 113                 "state\n", dev_name(&base->cdev->dev));
 114         spin_lock_irqsave(get_ccwdev_lock(base->cdev), flags);
 115         dasd_device_set_stop_bits(base, DASD_STOPPED_QUIESCE);
 116         spin_unlock_irqrestore(get_ccwdev_lock(base->cdev), flags);
 117         return 0;
 118 }
 119 
 120 
 121 /*
 122  * Resume device.
 123  */
 124 static int dasd_ioctl_resume(struct dasd_block *block)
 125 {
 126         unsigned long flags;
 127         struct dasd_device *base;
 128 
 129         base = block->base;
 130         if (!capable (CAP_SYS_ADMIN))
 131                 return -EACCES;
 132 
 133         pr_info("%s: I/O operations have been resumed "
 134                 "on the DASD\n", dev_name(&base->cdev->dev));
 135         spin_lock_irqsave(get_ccwdev_lock(base->cdev), flags);
 136         dasd_device_remove_stop_bits(base, DASD_STOPPED_QUIESCE);
 137         spin_unlock_irqrestore(get_ccwdev_lock(base->cdev), flags);
 138 
 139         dasd_schedule_block_bh(block);
 140         return 0;
 141 }
 142 
 143 /*
 144  * Abort all failfast I/O on a device.
 145  */
 146 static int dasd_ioctl_abortio(struct dasd_block *block)
 147 {
 148         unsigned long flags;
 149         struct dasd_device *base;
 150         struct dasd_ccw_req *cqr, *n;
 151 
 152         base = block->base;
 153         if (!capable(CAP_SYS_ADMIN))
 154                 return -EACCES;
 155 
 156         if (test_and_set_bit(DASD_FLAG_ABORTALL, &base->flags))
 157                 return 0;
 158         DBF_DEV_EVENT(DBF_NOTICE, base, "%s", "abortall flag set");
 159 
 160         spin_lock_irqsave(&block->request_queue_lock, flags);
 161         spin_lock(&block->queue_lock);
 162         list_for_each_entry_safe(cqr, n, &block->ccw_queue, blocklist) {
 163                 if (test_bit(DASD_CQR_FLAGS_FAILFAST, &cqr->flags) &&
 164                     cqr->callback_data &&
 165                     cqr->callback_data != DASD_SLEEPON_START_TAG &&
 166                     cqr->callback_data != DASD_SLEEPON_END_TAG) {
 167                         spin_unlock(&block->queue_lock);
 168                         blk_abort_request(cqr->callback_data);
 169                         spin_lock(&block->queue_lock);
 170                 }
 171         }
 172         spin_unlock(&block->queue_lock);
 173         spin_unlock_irqrestore(&block->request_queue_lock, flags);
 174 
 175         dasd_schedule_block_bh(block);
 176         return 0;
 177 }
 178 
 179 /*
 180  * Allow I/O on a device
 181  */
 182 static int dasd_ioctl_allowio(struct dasd_block *block)
 183 {
 184         struct dasd_device *base;
 185 
 186         base = block->base;
 187         if (!capable(CAP_SYS_ADMIN))
 188                 return -EACCES;
 189 
 190         if (test_and_clear_bit(DASD_FLAG_ABORTALL, &base->flags))
 191                 DBF_DEV_EVENT(DBF_NOTICE, base, "%s", "abortall flag unset");
 192 
 193         return 0;
 194 }
 195 
 196 /*
 197  * performs formatting of _device_ according to _fdata_
 198  * Note: The discipline's format_function is assumed to deliver formatting
 199  * commands to format multiple units of the device. In terms of the ECKD
 200  * devices this means CCWs are generated to format multiple tracks.
 201  */
 202 static int
 203 dasd_format(struct dasd_block *block, struct format_data_t *fdata)
 204 {
 205         struct dasd_device *base;
 206         int rc;
 207 
 208         base = block->base;
 209         if (base->discipline->format_device == NULL)
 210                 return -EPERM;
 211 
 212         if (base->state != DASD_STATE_BASIC) {
 213                 pr_warn("%s: The DASD cannot be formatted while it is enabled\n",
 214                         dev_name(&base->cdev->dev));
 215                 return -EBUSY;
 216         }
 217 
 218         DBF_DEV_EVENT(DBF_NOTICE, base,
 219                       "formatting units %u to %u (%u B blocks) flags %u",
 220                       fdata->start_unit,
 221                       fdata->stop_unit, fdata->blksize, fdata->intensity);
 222 
 223         /* Since dasdfmt keeps the device open after it was disabled,
 224          * there still exists an inode for this device.
 225          * We must update i_blkbits, otherwise we might get errors when
 226          * enabling the device later.
 227          */
 228         if (fdata->start_unit == 0) {
 229                 struct block_device *bdev = bdget_disk(block->gdp, 0);
 230                 bdev->bd_inode->i_blkbits = blksize_bits(fdata->blksize);
 231                 bdput(bdev);
 232         }
 233 
 234         rc = base->discipline->format_device(base, fdata, 1);
 235         if (rc == -EAGAIN)
 236                 rc = base->discipline->format_device(base, fdata, 0);
 237 
 238         return rc;
 239 }
 240 
 241 static int dasd_check_format(struct dasd_block *block,
 242                              struct format_check_t *cdata)
 243 {
 244         struct dasd_device *base;
 245         int rc;
 246 
 247         base = block->base;
 248         if (!base->discipline->check_device_format)
 249                 return -ENOTTY;
 250 
 251         rc = base->discipline->check_device_format(base, cdata, 1);
 252         if (rc == -EAGAIN)
 253                 rc = base->discipline->check_device_format(base, cdata, 0);
 254 
 255         return rc;
 256 }
 257 
 258 /*
 259  * Format device.
 260  */
 261 static int
 262 dasd_ioctl_format(struct block_device *bdev, void __user *argp)
 263 {
 264         struct dasd_device *base;
 265         struct format_data_t fdata;
 266         int rc;
 267 
 268         if (!capable(CAP_SYS_ADMIN))
 269                 return -EACCES;
 270         if (!argp)
 271                 return -EINVAL;
 272         base = dasd_device_from_gendisk(bdev->bd_disk);
 273         if (!base)
 274                 return -ENODEV;
 275         if (base->features & DASD_FEATURE_READONLY ||
 276             test_bit(DASD_FLAG_DEVICE_RO, &base->flags)) {
 277                 dasd_put_device(base);
 278                 return -EROFS;
 279         }
 280         if (copy_from_user(&fdata, argp, sizeof(struct format_data_t))) {
 281                 dasd_put_device(base);
 282                 return -EFAULT;
 283         }
 284         if (bdev != bdev->bd_contains) {
 285                 pr_warn("%s: The specified DASD is a partition and cannot be formatted\n",
 286                         dev_name(&base->cdev->dev));
 287                 dasd_put_device(base);
 288                 return -EINVAL;
 289         }
 290         rc = dasd_format(base->block, &fdata);
 291         dasd_put_device(base);
 292 
 293         return rc;
 294 }
 295 
 296 /*
 297  * Check device format
 298  */
 299 static int dasd_ioctl_check_format(struct block_device *bdev, void __user *argp)
 300 {
 301         struct format_check_t cdata;
 302         struct dasd_device *base;
 303         int rc = 0;
 304 
 305         if (!argp)
 306                 return -EINVAL;
 307 
 308         base = dasd_device_from_gendisk(bdev->bd_disk);
 309         if (!base)
 310                 return -ENODEV;
 311         if (bdev != bdev->bd_contains) {
 312                 pr_warn("%s: The specified DASD is a partition and cannot be checked\n",
 313                         dev_name(&base->cdev->dev));
 314                 rc = -EINVAL;
 315                 goto out_err;
 316         }
 317 
 318         if (copy_from_user(&cdata, argp, sizeof(cdata))) {
 319                 rc = -EFAULT;
 320                 goto out_err;
 321         }
 322 
 323         rc = dasd_check_format(base->block, &cdata);
 324         if (rc)
 325                 goto out_err;
 326 
 327         if (copy_to_user(argp, &cdata, sizeof(cdata)))
 328                 rc = -EFAULT;
 329 
 330 out_err:
 331         dasd_put_device(base);
 332 
 333         return rc;
 334 }
 335 
 336 static int dasd_release_space(struct dasd_device *device,
 337                               struct format_data_t *rdata)
 338 {
 339         if (!device->discipline->is_ese && !device->discipline->is_ese(device))
 340                 return -ENOTSUPP;
 341         if (!device->discipline->release_space)
 342                 return -ENOTSUPP;
 343 
 344         return device->discipline->release_space(device, rdata);
 345 }
 346 
 347 /*
 348  * Release allocated space
 349  */
 350 static int dasd_ioctl_release_space(struct block_device *bdev, void __user *argp)
 351 {
 352         struct format_data_t rdata;
 353         struct dasd_device *base;
 354         int rc = 0;
 355 
 356         if (!capable(CAP_SYS_ADMIN))
 357                 return -EACCES;
 358         if (!argp)
 359                 return -EINVAL;
 360 
 361         base = dasd_device_from_gendisk(bdev->bd_disk);
 362         if (!base)
 363                 return -ENODEV;
 364         if (base->features & DASD_FEATURE_READONLY ||
 365             test_bit(DASD_FLAG_DEVICE_RO, &base->flags)) {
 366                 rc = -EROFS;
 367                 goto out_err;
 368         }
 369         if (bdev != bdev->bd_contains) {
 370                 pr_warn("%s: The specified DASD is a partition and tracks cannot be released\n",
 371                         dev_name(&base->cdev->dev));
 372                 rc = -EINVAL;
 373                 goto out_err;
 374         }
 375 
 376         if (copy_from_user(&rdata, argp, sizeof(rdata))) {
 377                 rc = -EFAULT;
 378                 goto out_err;
 379         }
 380 
 381         rc = dasd_release_space(base, &rdata);
 382 
 383 out_err:
 384         dasd_put_device(base);
 385 
 386         return rc;
 387 }
 388 
 389 #ifdef CONFIG_DASD_PROFILE
 390 /*
 391  * Reset device profile information
 392  */
 393 static int dasd_ioctl_reset_profile(struct dasd_block *block)
 394 {
 395         dasd_profile_reset(&block->profile);
 396         return 0;
 397 }
 398 
 399 /*
 400  * Return device profile information
 401  */
 402 static int dasd_ioctl_read_profile(struct dasd_block *block, void __user *argp)
 403 {
 404         struct dasd_profile_info_t *data;
 405         int rc = 0;
 406 
 407         data = kmalloc(sizeof(*data), GFP_KERNEL);
 408         if (!data)
 409                 return -ENOMEM;
 410 
 411         spin_lock_bh(&block->profile.lock);
 412         if (block->profile.data) {
 413                 data->dasd_io_reqs = block->profile.data->dasd_io_reqs;
 414                 data->dasd_io_sects = block->profile.data->dasd_io_sects;
 415                 memcpy(data->dasd_io_secs, block->profile.data->dasd_io_secs,
 416                        sizeof(data->dasd_io_secs));
 417                 memcpy(data->dasd_io_times, block->profile.data->dasd_io_times,
 418                        sizeof(data->dasd_io_times));
 419                 memcpy(data->dasd_io_timps, block->profile.data->dasd_io_timps,
 420                        sizeof(data->dasd_io_timps));
 421                 memcpy(data->dasd_io_time1, block->profile.data->dasd_io_time1,
 422                        sizeof(data->dasd_io_time1));
 423                 memcpy(data->dasd_io_time2, block->profile.data->dasd_io_time2,
 424                        sizeof(data->dasd_io_time2));
 425                 memcpy(data->dasd_io_time2ps,
 426                        block->profile.data->dasd_io_time2ps,
 427                        sizeof(data->dasd_io_time2ps));
 428                 memcpy(data->dasd_io_time3, block->profile.data->dasd_io_time3,
 429                        sizeof(data->dasd_io_time3));
 430                 memcpy(data->dasd_io_nr_req,
 431                        block->profile.data->dasd_io_nr_req,
 432                        sizeof(data->dasd_io_nr_req));
 433                 spin_unlock_bh(&block->profile.lock);
 434         } else {
 435                 spin_unlock_bh(&block->profile.lock);
 436                 rc = -EIO;
 437                 goto out;
 438         }
 439         if (copy_to_user(argp, data, sizeof(*data)))
 440                 rc = -EFAULT;
 441 out:
 442         kfree(data);
 443         return rc;
 444 }
 445 #else
 446 static int dasd_ioctl_reset_profile(struct dasd_block *block)
 447 {
 448         return -ENOTTY;
 449 }
 450 
 451 static int dasd_ioctl_read_profile(struct dasd_block *block, void __user *argp)
 452 {
 453         return -ENOTTY;
 454 }
 455 #endif
 456 
 457 /*
 458  * Return dasd information. Used for BIODASDINFO and BIODASDINFO2.
 459  */
 460 static int dasd_ioctl_information(struct dasd_block *block,
 461                                   unsigned int cmd, void __user *argp)
 462 {
 463         struct dasd_information2_t *dasd_info;
 464         struct subchannel_id sch_id;
 465         struct ccw_dev_id dev_id;
 466         struct dasd_device *base;
 467         struct ccw_device *cdev;
 468         struct list_head *l;
 469         unsigned long flags;
 470         int rc;
 471 
 472         base = block->base;
 473         if (!base->discipline || !base->discipline->fill_info)
 474                 return -EINVAL;
 475 
 476         dasd_info = kzalloc(sizeof(struct dasd_information2_t), GFP_KERNEL);
 477         if (dasd_info == NULL)
 478                 return -ENOMEM;
 479 
 480         rc = base->discipline->fill_info(base, dasd_info);
 481         if (rc) {
 482                 kfree(dasd_info);
 483                 return rc;
 484         }
 485 
 486         cdev = base->cdev;
 487         ccw_device_get_id(cdev, &dev_id);
 488         ccw_device_get_schid(cdev, &sch_id);
 489 
 490         dasd_info->devno = dev_id.devno;
 491         dasd_info->schid = sch_id.sch_no;
 492         dasd_info->cu_type = cdev->id.cu_type;
 493         dasd_info->cu_model = cdev->id.cu_model;
 494         dasd_info->dev_type = cdev->id.dev_type;
 495         dasd_info->dev_model = cdev->id.dev_model;
 496         dasd_info->status = base->state;
 497         /*
 498          * The open_count is increased for every opener, that includes
 499          * the blkdev_get in dasd_scan_partitions.
 500          * This must be hidden from user-space.
 501          */
 502         dasd_info->open_count = atomic_read(&block->open_count);
 503         if (!block->bdev)
 504                 dasd_info->open_count++;
 505 
 506         /*
 507          * check if device is really formatted
 508          * LDL / CDL was returned by 'fill_info'
 509          */
 510         if ((base->state < DASD_STATE_READY) ||
 511             (dasd_check_blocksize(block->bp_block)))
 512                 dasd_info->format = DASD_FORMAT_NONE;
 513 
 514         dasd_info->features |=
 515                 ((base->features & DASD_FEATURE_READONLY) != 0);
 516 
 517         memcpy(dasd_info->type, base->discipline->name, 4);
 518 
 519         spin_lock_irqsave(&block->queue_lock, flags);
 520         list_for_each(l, &base->ccw_queue)
 521                 dasd_info->chanq_len++;
 522         spin_unlock_irqrestore(&block->queue_lock, flags);
 523 
 524         rc = 0;
 525         if (copy_to_user(argp, dasd_info,
 526                          ((cmd == (unsigned int) BIODASDINFO2) ?
 527                           sizeof(struct dasd_information2_t) :
 528                           sizeof(struct dasd_information_t))))
 529                 rc = -EFAULT;
 530         kfree(dasd_info);
 531         return rc;
 532 }
 533 
 534 /*
 535  * Set read only
 536  */
 537 static int
 538 dasd_ioctl_set_ro(struct block_device *bdev, void __user *argp)
 539 {
 540         struct dasd_device *base;
 541         int intval, rc;
 542 
 543         if (!capable(CAP_SYS_ADMIN))
 544                 return -EACCES;
 545         if (bdev != bdev->bd_contains)
 546                 // ro setting is not allowed for partitions
 547                 return -EINVAL;
 548         if (get_user(intval, (int __user *)argp))
 549                 return -EFAULT;
 550         base = dasd_device_from_gendisk(bdev->bd_disk);
 551         if (!base)
 552                 return -ENODEV;
 553         if (!intval && test_bit(DASD_FLAG_DEVICE_RO, &base->flags)) {
 554                 dasd_put_device(base);
 555                 return -EROFS;
 556         }
 557         set_disk_ro(bdev->bd_disk, intval);
 558         rc = dasd_set_feature(base->cdev, DASD_FEATURE_READONLY, intval);
 559         dasd_put_device(base);
 560         return rc;
 561 }
 562 
 563 static int dasd_ioctl_readall_cmb(struct dasd_block *block, unsigned int cmd,
 564                                   struct cmbdata __user *argp)
 565 {
 566         size_t size = _IOC_SIZE(cmd);
 567         struct cmbdata data;
 568         int ret;
 569 
 570         ret = cmf_readall(block->base->cdev, &data);
 571         if (!ret && copy_to_user(argp, &data, min(size, sizeof(*argp))))
 572                 return -EFAULT;
 573         return ret;
 574 }
 575 
 576 int dasd_ioctl(struct block_device *bdev, fmode_t mode,
 577                unsigned int cmd, unsigned long arg)
 578 {
 579         struct dasd_block *block;
 580         struct dasd_device *base;
 581         void __user *argp;
 582         int rc;
 583 
 584         if (is_compat_task())
 585                 argp = compat_ptr(arg);
 586         else
 587                 argp = (void __user *)arg;
 588 
 589         if ((_IOC_DIR(cmd) != _IOC_NONE) && !arg) {
 590                 PRINT_DEBUG("empty data ptr");
 591                 return -EINVAL;
 592         }
 593 
 594         base = dasd_device_from_gendisk(bdev->bd_disk);
 595         if (!base)
 596                 return -ENODEV;
 597         block = base->block;
 598         rc = 0;
 599         switch (cmd) {
 600         case BIODASDDISABLE:
 601                 rc = dasd_ioctl_disable(bdev);
 602                 break;
 603         case BIODASDENABLE:
 604                 rc = dasd_ioctl_enable(bdev);
 605                 break;
 606         case BIODASDQUIESCE:
 607                 rc = dasd_ioctl_quiesce(block);
 608                 break;
 609         case BIODASDRESUME:
 610                 rc = dasd_ioctl_resume(block);
 611                 break;
 612         case BIODASDABORTIO:
 613                 rc = dasd_ioctl_abortio(block);
 614                 break;
 615         case BIODASDALLOWIO:
 616                 rc = dasd_ioctl_allowio(block);
 617                 break;
 618         case BIODASDFMT:
 619                 rc = dasd_ioctl_format(bdev, argp);
 620                 break;
 621         case BIODASDCHECKFMT:
 622                 rc = dasd_ioctl_check_format(bdev, argp);
 623                 break;
 624         case BIODASDINFO:
 625                 rc = dasd_ioctl_information(block, cmd, argp);
 626                 break;
 627         case BIODASDINFO2:
 628                 rc = dasd_ioctl_information(block, cmd, argp);
 629                 break;
 630         case BIODASDPRRD:
 631                 rc = dasd_ioctl_read_profile(block, argp);
 632                 break;
 633         case BIODASDPRRST:
 634                 rc = dasd_ioctl_reset_profile(block);
 635                 break;
 636         case BLKROSET:
 637                 rc = dasd_ioctl_set_ro(bdev, argp);
 638                 break;
 639         case DASDAPIVER:
 640                 rc = dasd_ioctl_api_version(argp);
 641                 break;
 642         case BIODASDCMFENABLE:
 643                 rc = enable_cmf(base->cdev);
 644                 break;
 645         case BIODASDCMFDISABLE:
 646                 rc = disable_cmf(base->cdev);
 647                 break;
 648         case BIODASDREADALLCMB:
 649                 rc = dasd_ioctl_readall_cmb(block, cmd, argp);
 650                 break;
 651         case BIODASDRAS:
 652                 rc = dasd_ioctl_release_space(bdev, argp);
 653                 break;
 654         default:
 655                 /* if the discipline has an ioctl method try it. */
 656                 rc = -ENOTTY;
 657                 if (base->discipline->ioctl)
 658                         rc = base->discipline->ioctl(block, cmd, argp);
 659         }
 660         dasd_put_device(base);
 661         return rc;
 662 }