sys/dev/disk/dm/device-mapper.c

   1 /*        $NetBSD: device-mapper.c,v 1.22 2010/03/26 15:46:04 jakllsch Exp $ */
   2
   3 /*
   4  * Copyright (c) 2010 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Adam Hamsik.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * I want to say thank you to all people who helped me with this project.
  34  */
  35
  36 #include <sys/types.h>
  37 #include <sys/param.h>
  38
  39 #include <sys/buf.h>
  40 #include <sys/conf.h>
  41 #include <sys/device.h>
  42 #include <sys/devfs.h>
  43 #include <sys/disk.h>
  44 #include <sys/disklabel.h>
  45 #include <sys/dtype.h>
  46 #include <sys/ioccom.h>
  47 #include <sys/malloc.h>
  48 #include <sys/module.h>
  49 #include <sys/sysctl.h>
  50 #include <dev/disk/dm/dm.h>
  51
  52 #include "netbsd-dm.h"
  53
  54 static  d_ioctl_t       dmioctl;
  55 static  d_open_t        dmopen;
  56 static  d_close_t       dmclose;
  57 static  d_psize_t       dmsize;
  58 static  d_strategy_t    dmstrategy;
  59 static  d_dump_t        dmdump;
  60
  61 /* attach and detach routines */
  62 void dmattach(int);
  63 static int dm_modcmd(module_t mod, int cmd, void *unused);
  64 static int dmdestroy(void);
  65
  66 static void dm_doinit(void);
  67
  68 static int dm_cmd_to_fun(prop_dictionary_t);
  69 static int disk_ioctl_switch(cdev_t, u_long, void *);
  70 static int dm_ioctl_switch(u_long);
  71 #if 0
  72 static void dmminphys(struct buf *);
  73 #endif
  74
  75 struct devfs_bitmap dm_minor_bitmap;
  76
  77 /* ***Variable-definitions*** */
  78 struct dev_ops dm_ops = {
  79         { "dm", 0, D_DISK | D_MPSAFE },
  80         .d_open         = dmopen,
  81         .d_close        = dmclose,
  82         .d_read         = physread,
  83         .d_write        = physwrite,
  84         .d_ioctl        = dmioctl,
  85         .d_strategy     = dmstrategy,
  86         .d_psize        = dmsize,
  87         .d_dump         = dmdump,
  88 /* D_DISK */
  89 };
  90
  91 MALLOC_DEFINE(M_DM, "dm", "Device Mapper allocations");
  92
  93 int dm_debug_level = 0;
  94
  95 extern uint64_t dm_dev_counter;
  96
  97 static cdev_t dmcdev;
  98
  99 static moduledata_t dm_mod = {
 100     "dm",
 101     dm_modcmd,
 102     NULL
 103 };
 104 DECLARE_MODULE(dm, dm_mod, SI_SUB_RAID, SI_ORDER_ANY);
 105 MODULE_VERSION(dm, 1);
 106
 107 /*
 108  * This array is used to translate cmd to function pointer.
 109  *
 110  * Interface between libdevmapper and lvm2tools uses different
 111  * names for one IOCTL call because libdevmapper do another thing
 112  * then. When I run "info" or "mknodes" libdevmapper will send same
 113  * ioctl to kernel but will do another things in userspace.
 114  *
 115  */
 116 static struct cmd_function cmd_fn[] = {
 117                 { .cmd = "version", .fn = dm_get_version_ioctl},
 118                 { .cmd = "targets", .fn = dm_list_versions_ioctl},
 119                 { .cmd = "create",  .fn = dm_dev_create_ioctl},
 120                 { .cmd = "info",    .fn = dm_dev_status_ioctl},
 121                 { .cmd = "mknodes", .fn = dm_dev_status_ioctl},
 122                 { .cmd = "names",   .fn = dm_dev_list_ioctl},
 123                 { .cmd = "suspend", .fn = dm_dev_suspend_ioctl},
 124                 { .cmd = "remove",  .fn = dm_dev_remove_ioctl},
 125                 { .cmd = "rename",  .fn = dm_dev_rename_ioctl},
 126                 { .cmd = "resume",  .fn = dm_dev_resume_ioctl},
 127                 { .cmd = "clear",   .fn = dm_table_clear_ioctl},
 128                 { .cmd = "deps",    .fn = dm_table_deps_ioctl},
 129                 { .cmd = "reload",  .fn = dm_table_load_ioctl},
 130                 { .cmd = "status",  .fn = dm_table_status_ioctl},
 131                 { .cmd = "table",   .fn = dm_table_status_ioctl},
 132                 {NULL, NULL}
 133 };
 134
 135 /* New module handle routine */
 136 static int
 137 dm_modcmd(module_t mod, int cmd, void *unused)
 138 {
 139         int error, bmajor, cmajor;
 140
 141         error = 0;
 142         bmajor = -1;
 143         cmajor = -1;
 144
 145         switch (cmd) {
 146         case MOD_LOAD:
 147                 devfs_clone_bitmap_init(&dm_minor_bitmap);
 148                 dm_doinit();
 149                 kprintf("Device Mapper version %d.%d.%d loaded\n",
 150                     DM_VERSION_MAJOR, DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL);
 151                 break;
 152
 153         case MOD_UNLOAD:
 154                 /*
 155                  * Disable unloading of dm module if there are any devices
 156                  * defined in driver. This is probably too strong we need
 157                  * to disable auto-unload only if there is mounted dm device
 158                  * present.
 159                  */
 160                 if (dm_dev_counter > 0)
 161                         return EBUSY;
 162
 163                 error = dmdestroy();
 164                 if (error)
 165                         break;
 166                 kprintf("Device Mapper unloaded\n");
 167                 break;
 168
 169         default:
 170                 break;
 171         }
 172
 173         return error;
 174 }
 175
 176 /*
 177  * dm_detach is called to completely destroy & remove a dm disk device.
 178  */
 179 int
 180 dm_detach(dm_dev_t *dmv)
 181 {
 182         int minor;
 183
 184         /* Remove device from list and wait for refcnt to drop to zero */
 185         dm_dev_rem(dmv, NULL, NULL, -1);
 186
 187         /* Destroy active table first.  */
 188         dm_table_destroy(&dmv->table_head, DM_TABLE_ACTIVE);
 189
 190         /* Destroy inactive table if exits, too. */
 191         dm_table_destroy(&dmv->table_head, DM_TABLE_INACTIVE);
 192
 193         dm_table_head_destroy(&dmv->table_head);
 194
 195         minor = dkunit(dmv->devt);
 196         disk_destroy(dmv->diskp);
 197         devstat_remove_entry(&dmv->stats);
 198
 199         release_dev(dmv->devt);
 200         devfs_clone_bitmap_put(&dm_minor_bitmap, minor);
 201
 202         /* Destroy device */
 203         (void)dm_dev_free(dmv);
 204
 205         /* Decrement device counter After removing device */
 206         --dm_dev_counter; /* XXX: was atomic 64 */
 207
 208         return 0;
 209 }
 210
 211 static void
 212 dm_doinit(void)
 213 {
 214         dm_target_init();
 215         dm_dev_init();
 216         dm_pdev_init();
 217         dmcdev = make_dev(&dm_ops, 0, UID_ROOT, GID_OPERATOR, 0640, "mapper/control");
 218 }
 219
 220 /* Destroy routine */
 221 static int
 222 dmdestroy(void)
 223 {
 224         destroy_dev(dmcdev);
 225
 226         dm_dev_destroy();
 227         dm_pdev_destroy();
 228         dm_target_destroy();
 229
 230         return 0;
 231 }
 232
 233 static int
 234 dmopen(struct dev_open_args *ap)
 235 {
 236         cdev_t dev = ap->a_head.a_dev;
 237         dm_dev_t *dmv;
 238
 239         /* Shortcut for the control device */
 240         if (minor(dev) == 0)
 241                 return 0;
 242
 243         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL)
 244                 return ENXIO;
 245
 246         dmv->is_open = 1;
 247         dm_dev_unbusy(dmv);
 248
 249         aprint_debug("dm open routine called %" PRIu32 "\n",
 250             minor(ap->a_head.a_dev));
 251         return 0;
 252 }
 253
 254 static int
 255 dmclose(struct dev_close_args *ap)
 256 {
 257         cdev_t dev = ap->a_head.a_dev;
 258         dm_dev_t *dmv;
 259
 260         /* Shortcut for the control device */
 261         if (minor(dev) == 0)
 262                 return 0;
 263
 264         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL)
 265                 return ENXIO;
 266
 267         dmv->is_open = 0;
 268         dm_dev_unbusy(dmv);
 269
 270         aprint_debug("dm close routine called %" PRIu32 "\n",
 271             minor(ap->a_head.a_dev));
 272         return 0;
 273 }
 274
 275
 276 static int
 277 dmioctl(struct dev_ioctl_args *ap)
 278 {
 279         cdev_t dev = ap->a_head.a_dev;
 280         u_long cmd = ap->a_cmd;
 281         void *data = ap->a_data;
 282
 283         int r, err;
 284         prop_dictionary_t dm_dict_in;
 285
 286         err = r = 0;
 287
 288         aprint_debug("dmioctl called\n");
 289
 290         KKASSERT(data != NULL);
 291
 292         if (( r = disk_ioctl_switch(dev, cmd, data)) == ENOTTY) {
 293                 struct plistref *pref = (struct plistref *) data;
 294
 295                 /* Check if we were called with NETBSD_DM_IOCTL ioctl
 296                    otherwise quit. */
 297                 if ((r = dm_ioctl_switch(cmd)) != 0)
 298                         return r;
 299
 300                 if((r = prop_dictionary_copyin_ioctl(pref, cmd, &dm_dict_in)) != 0)
 301                         return r;
 302
 303                 if ((r = dm_check_version(dm_dict_in)) != 0)
 304                         goto cleanup_exit;
 305
 306                 /* run ioctl routine */
 307                 if ((err = dm_cmd_to_fun(dm_dict_in)) != 0)
 308                         goto cleanup_exit;
 309
 310 cleanup_exit:
 311                 r = prop_dictionary_copyout_ioctl(pref, cmd, dm_dict_in);
 312                 prop_object_release(dm_dict_in);
 313         }
 314
 315         /*
 316          * Return the error of the actual command if one one has
 317          * happened. Otherwise return 'r' which indicates errors
 318          * that occurred during helper operations.
 319          */
 320         return (err != 0)?err:r;
 321 }
 322
 323 /*
 324  * Translate command sent from libdevmapper to func.
 325  */
 326 static int
 327 dm_cmd_to_fun(prop_dictionary_t dm_dict){
 328         int i, r;
 329         prop_string_t command;
 330
 331         r = 0;
 332
 333         if ((command = prop_dictionary_get(dm_dict, DM_IOCTL_COMMAND)) == NULL)
 334                 return EINVAL;
 335
 336         for(i = 0; cmd_fn[i].cmd != NULL; i++)
 337                 if (prop_string_equals_cstring(command, cmd_fn[i].cmd))
 338                         break;
 339
 340         if (cmd_fn[i].cmd == NULL)
 341                 return EINVAL;
 342
 343         aprint_debug("ioctl %s called\n", cmd_fn[i].cmd);
 344         r = cmd_fn[i].fn(dm_dict);
 345
 346         return r;
 347 }
 348
 349 /* Call apropriate ioctl handler function. */
 350 static int
 351 dm_ioctl_switch(u_long cmd)
 352 {
 353
 354         switch(cmd) {
 355
 356         case NETBSD_DM_IOCTL:
 357                 aprint_debug("dm NetBSD_DM_IOCTL called\n");
 358                 break;
 359         default:
 360                  aprint_debug("dm unknown ioctl called\n");
 361                  return ENOTTY;
 362                  break; /* NOT REACHED */
 363         }
 364
 365          return 0;
 366 }
 367
 368  /*
 369   * Check for disk specific ioctls.
 370   */
 371
 372 static int
 373 disk_ioctl_switch(cdev_t dev, u_long cmd, void *data)
 374 {
 375         dm_dev_t *dmv;
 376
 377         /* disk ioctls make sense only on block devices */
 378         if (minor(dev) == 0)
 379                 return ENOTTY;
 380
 381         switch(cmd) {
 382         case DIOCGPART:
 383         {
 384                 struct partinfo *dpart;
 385                 u_int64_t size;
 386                 dpart = (void *)data;
 387                 bzero(dpart, sizeof(*dpart));
 388
 389                 if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL)
 390                         return ENODEV;
 391                 if (dmv->diskp->d_info.d_media_blksize == 0) {
 392                         dm_dev_unbusy(dmv);
 393                         return ENOTSUP;
 394                 } else {
 395                         size = dm_table_size(&dmv->table_head);
 396                         dpart->media_offset  = 0;
 397                         dpart->media_size    = size * DEV_BSIZE;
 398                         dpart->media_blocks  = size;
 399                         dpart->media_blksize = DEV_BSIZE;
 400                         dpart->fstype = FS_BSDFFS;
 401                 }
 402                 dm_dev_unbusy(dmv);
 403                 break;
 404         }
 405
 406         default:
 407                 aprint_debug("unknown disk_ioctl called\n");
 408                 return ENOTTY;
 409                 break; /* NOT REACHED */
 410         }
 411
 412         return 0;
 413 }
 414
 415 /*
 416  * Do all IO operations on dm logical devices.
 417  */
 418 static int
 419 dmstrategy(struct dev_strategy_args *ap)
 420 {
 421         cdev_t dev = ap->a_head.a_dev;
 422         struct bio *bio = ap->a_bio;
 423         struct buf *bp = bio->bio_buf;
 424         int bypass;
 425
 426         dm_dev_t *dmv;
 427         dm_table_t  *tbl;
 428         dm_table_entry_t *table_en;
 429         struct buf *nestbuf;
 430
 431         uint32_t dev_type;
 432
 433         uint64_t buf_start, buf_len, issued_len;
 434         uint64_t table_start, table_end;
 435         uint64_t start, end;
 436
 437         buf_start = bio->bio_offset;
 438         buf_len = bp->b_bcount;
 439
 440         tbl = NULL;
 441
 442         table_end = 0;
 443         dev_type = 0;
 444         issued_len = 0;
 445
 446         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL) {
 447                 bp->b_error = EIO;
 448                 bp->b_resid = bp->b_bcount;
 449                 biodone(bio);
 450                 return 0;
 451         }
 452
 453         switch(bp->b_cmd) {
 454         case BUF_CMD_READ:
 455         case BUF_CMD_WRITE:
 456         case BUF_CMD_FREEBLKS:
 457                 bypass = 0;
 458                 break;
 459         case BUF_CMD_FLUSH:
 460                 bypass = 1;
 461                 KKASSERT(buf_len == 0);
 462                 break;
 463         default:
 464                 dm_dev_unbusy(dmv);
 465                 bp->b_error = EIO;
 466                 bp->b_resid = bp->b_bcount;
 467                 biodone(bio);
 468                 return 0;
 469         }
 470
 471         if (bypass == 0 &&
 472             bounds_check_with_mediasize(bio, DEV_BSIZE,
 473                                         dm_table_size(&dmv->table_head)) <= 0) {
 474                 dm_dev_unbusy(dmv);
 475                 bp->b_resid = bp->b_bcount;
 476                 biodone(bio);
 477                 return 0;
 478         }
 479
 480         /* Select active table */
 481         tbl = dm_table_get_entry(&dmv->table_head, DM_TABLE_ACTIVE);
 482
 483         nestiobuf_init(bio);
 484         devstat_start_transaction(&dmv->stats);
 485
 486         /*
 487          * Find out what tables I want to select.
 488          */
 489         SLIST_FOREACH(table_en, tbl, next) {
 490                 /*
 491                  * I need need number of bytes not blocks.
 492                  */
 493                 table_start = table_en->start * DEV_BSIZE;
 494                 table_end = table_start + (table_en->length) * DEV_BSIZE;
 495
 496                 /*
 497                  * Calculate the start and end
 498                  */
 499                 start = MAX(table_start, buf_start);
 500                 end = MIN(table_end, buf_start + buf_len);
 501
 502                 aprint_debug("----------------------------------------\n");
 503                 aprint_debug("table_start %010" PRIu64", table_end %010"
 504                     PRIu64 "\n", table_start, table_end);
 505                 aprint_debug("buf_start %010" PRIu64", buf_len %010"
 506                     PRIu64"\n", buf_start, buf_len);
 507                 aprint_debug("start-buf_start %010"PRIu64", end %010"
 508                     PRIu64"\n", start - buf_start, end);
 509                 aprint_debug("start %010" PRIu64" , end %010"
 510                     PRIu64"\n", start, end);
 511                 aprint_debug("\n----------------------------------------\n");
 512
 513                 if (bypass) {
 514                         nestbuf = getpbuf(NULL);
 515                         nestbuf->b_flags |= bio->bio_buf->b_flags & B_HASBOGUS;
 516
 517                         nestiobuf_add(bio, nestbuf, 0, 0, &dmv->stats);
 518                         nestbuf->b_bio1.bio_offset = 0;
 519                         table_en->target->strategy(table_en, nestbuf);
 520                 } else if (start < end) {
 521                         nestbuf = getpbuf(NULL);
 522                         nestbuf->b_flags |= bio->bio_buf->b_flags & B_HASBOGUS;
 523
 524                         nestiobuf_add(bio, nestbuf,
 525                                       start - buf_start, (end - start),
 526                                       &dmv->stats);
 527                         issued_len += end - start;
 528
 529                         nestbuf->b_bio1.bio_offset = (start - table_start);
 530                         table_en->target->strategy(table_en, nestbuf);
 531                 }
 532         }
 533
 534         if (issued_len < buf_len)
 535                 nestiobuf_error(bio, EINVAL);
 536         nestiobuf_start(bio);
 537         dm_table_release(&dmv->table_head, DM_TABLE_ACTIVE);
 538         dm_dev_unbusy(dmv);
 539
 540         return 0;
 541 }
 542
 543 static int
 544 dmdump(struct dev_dump_args *ap)
 545 {
 546         cdev_t dev = ap->a_head.a_dev;
 547         dm_dev_t *dmv;
 548         dm_table_t  *tbl;
 549         dm_table_entry_t *table_en;
 550         uint32_t dev_type;
 551         uint64_t buf_start, buf_len, issued_len;
 552         uint64_t table_start, table_end;
 553         uint64_t start, end, data_offset;
 554         off_t offset;
 555         size_t length;
 556         int error = 0;
 557
 558         buf_start = ap->a_offset;
 559         buf_len = ap->a_length;
 560
 561         tbl = NULL;
 562
 563         table_end = 0;
 564         dev_type = 0;
 565         issued_len = 0;
 566
 567         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL) {
 568                 return EIO;
 569         }
 570
 571         /* Select active table */
 572         tbl = dm_table_get_entry(&dmv->table_head, DM_TABLE_ACTIVE);
 573
 574
 575         /*
 576          * Find out what tables I want to select.
 577          */
 578         SLIST_FOREACH(table_en, tbl, next) {
 579                 /*
 580                  * I need need number of bytes not blocks.
 581                  */
 582                 table_start = table_en->start * DEV_BSIZE;
 583                 table_end = table_start + (table_en->length) * DEV_BSIZE;
 584
 585                 /*
 586                  * Calculate the start and end
 587                  */
 588                 start = MAX(table_start, buf_start);
 589                 end = MIN(table_end, buf_start + buf_len);
 590
 591                 if (ap->a_length == 0) {
 592                         if (table_en->target->dump == NULL) {
 593                                 error = ENXIO;
 594                                 goto out;
 595                         }
 596
 597                         table_en->target->dump(table_en, NULL, 0, 0);
 598                 } else if (start < end) {
 599                         data_offset = start - buf_start;
 600                         offset = start - table_start;
 601                         length = end - start;
 602
 603                         if (table_en->target->dump == NULL) {
 604                                 error = ENXIO;
 605                                 goto out;
 606                         }
 607
 608                         table_en->target->dump(table_en,
 609                             (char *)ap->a_virtual + data_offset,
 610                             length, offset);
 611
 612                         issued_len += end - start;
 613                 }
 614         }
 615
 616         if (issued_len < buf_len)
 617                 error = EINVAL;
 618
 619 out:
 620         dm_table_release(&dmv->table_head, DM_TABLE_ACTIVE);
 621         dm_dev_unbusy(dmv);
 622
 623         return error;
 624 }
 625
 626 static int
 627 dmsize(struct dev_psize_args *ap)
 628 {
 629         cdev_t dev = ap->a_head.a_dev;
 630         dm_dev_t *dmv;
 631         uint64_t size;
 632
 633         size = 0;
 634
 635         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL)
 636                         return ENOENT;
 637
 638         size = dm_table_size(&dmv->table_head);
 639         dm_dev_unbusy(dmv);
 640
 641         ap->a_result = (int64_t)size;
 642
 643         return 0;
 644 }
 645
 646 #if 0
 647 static void
 648 dmminphys(struct buf *bp)
 649 {
 650
 651         bp->b_bcount = MIN(bp->b_bcount, MAXPHYS);
 652 }
 653 #endif
 654
 655 void
 656 dmsetdiskinfo(struct disk *disk, dm_table_head_t *head)
 657 {
 658         struct disk_info info;
 659         uint64_t dmp_size;
 660
 661         dmp_size = dm_table_size(head);
 662
 663         bzero(&info, sizeof(struct disk_info));
 664         info.d_media_blksize = DEV_BSIZE;
 665         info.d_media_blocks = dmp_size;
 666 #if 0
 667         /* this is set by disk_setdiskinfo */
 668         info.d_media_size = dmp_size * DEV_BSIZE;
 669 #endif
 670         info.d_dsflags = DSO_MBRQUIET | DSO_DEVICEMAPPER;
 671
 672         info.d_secpertrack = 32;
 673         info.d_nheads = 64;
 674         info.d_secpercyl = info.d_secpertrack * info.d_nheads;
 675         info.d_ncylinders = dmp_size / info.d_secpercyl;
 676
 677         disk_setdiskinfo(disk, &info);
 678 }
 679
 680 void
 681 dm_builtin_init(void *arg)
 682 {
 683         modeventhand_t evh = (modeventhand_t)arg;
 684
 685         KKASSERT(evh != NULL);
 686         evh(NULL, MOD_LOAD, NULL);
 687 }
 688
 689 void
 690 dm_builtin_uninit(void *arg)
 691 {
 692         modeventhand_t evh = (modeventhand_t)arg;
 693
 694         KKASSERT(evh != NULL);
 695         evh(NULL, MOD_UNLOAD, NULL);
 696 }
 697
 698 TUNABLE_INT("debug.dm_debug", &dm_debug_level);
 699 SYSCTL_INT(_debug, OID_AUTO, dm_debug, CTLFLAG_RW, &dm_debug_level,
 700                0, "Eanble device mapper debugging");
 701