drivers/md/dm-ioctl.c

   1 /*
   2  * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
   3  * Copyright (C) 2004 - 2006 Red Hat, Inc. All rights reserved.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include "dm.h"
   9
  10 #include <linux/module.h>
  11 #include <linux/vmalloc.h>
  12 #include <linux/miscdevice.h>
  13 #include <linux/init.h>
  14 #include <linux/wait.h>
  15 #include <linux/slab.h>
  16 #include <linux/dm-ioctl.h>
  17 #include <linux/hdreg.h>
  18 #include <linux/compat.h>
  19
  20 #include <asm/uaccess.h>
  21
  22 #define DM_MSG_PREFIX "ioctl"
  23 #define DM_DRIVER_EMAIL "dm-devel@redhat.com"
  24
  25 /*-----------------------------------------------------------------
  26  * The ioctl interface needs to be able to look up devices by
  27  * name or uuid.
  28  *---------------------------------------------------------------*/
  29 struct hash_cell {
  30         struct list_head name_list;
  31         struct list_head uuid_list;
  32
  33         char *name;
  34         char *uuid;
  35         struct mapped_device *md;
  36         struct dm_table *new_map;
  37 };
  38
  39 struct vers_iter {
  40     size_t param_size;
  41     struct dm_target_versions *vers, *old_vers;
  42     char *end;
  43     uint32_t flags;
  44 };
  45
  46
  47 #define NUM_BUCKETS 64
  48 #define MASK_BUCKETS (NUM_BUCKETS - 1)
  49 static struct list_head _name_buckets[NUM_BUCKETS];
  50 static struct list_head _uuid_buckets[NUM_BUCKETS];
  51
  52 static void dm_hash_remove_all(int keep_open_devices);
  53
  54 /*
  55  * Guards access to both hash tables.
  56  */
  57 static DECLARE_RWSEM(_hash_lock);
  58
  59 static void init_buckets(struct list_head *buckets)
  60 {
  61         unsigned int i;
  62
  63         for (i = 0; i < NUM_BUCKETS; i++)
  64                 INIT_LIST_HEAD(buckets + i);
  65 }
  66
  67 static int dm_hash_init(void)
  68 {
  69         init_buckets(_name_buckets);
  70         init_buckets(_uuid_buckets);
  71         return 0;
  72 }
  73
  74 static void dm_hash_exit(void)
  75 {
  76         dm_hash_remove_all(0);
  77 }
  78
  79 /*-----------------------------------------------------------------
  80  * Hash function:
  81  * We're not really concerned with the str hash function being
  82  * fast since it's only used by the ioctl interface.
  83  *---------------------------------------------------------------*/
  84 static unsigned int hash_str(const char *str)
  85 {
  86         const unsigned int hash_mult = 2654435387U;
  87         unsigned int h = 0;
  88
  89         while (*str)
  90                 h = (h + (unsigned int) *str++) * hash_mult;
  91
  92         return h & MASK_BUCKETS;
  93 }
  94
  95 /*-----------------------------------------------------------------
  96  * Code for looking up a device by name
  97  *---------------------------------------------------------------*/
  98 static struct hash_cell *__get_name_cell(const char *str)
  99 {
 100         struct hash_cell *hc;
 101         unsigned int h = hash_str(str);
 102
 103         list_for_each_entry (hc, _name_buckets + h, name_list)
 104                 if (!strcmp(hc->name, str)) {
 105                         dm_get(hc->md);
 106                         return hc;
 107                 }
 108
 109         return NULL;
 110 }
 111
 112 static struct hash_cell *__get_uuid_cell(const char *str)
 113 {
 114         struct hash_cell *hc;
 115         unsigned int h = hash_str(str);
 116
 117         list_for_each_entry (hc, _uuid_buckets + h, uuid_list)
 118                 if (!strcmp(hc->uuid, str)) {
 119                         dm_get(hc->md);
 120                         return hc;
 121                 }
 122
 123         return NULL;
 124 }
 125
 126 /*-----------------------------------------------------------------
 127  * Inserting, removing and renaming a device.
 128  *---------------------------------------------------------------*/
 129 static struct hash_cell *alloc_cell(const char *name, const char *uuid,
 130                                     struct mapped_device *md)
 131 {
 132         struct hash_cell *hc;
 133
 134         hc = kmalloc(sizeof(*hc), GFP_KERNEL);
 135         if (!hc)
 136                 return NULL;
 137
 138         hc->name = kstrdup(name, GFP_KERNEL);
 139         if (!hc->name) {
 140                 kfree(hc);
 141                 return NULL;
 142         }
 143
 144         if (!uuid)
 145                 hc->uuid = NULL;
 146
 147         else {
 148                 hc->uuid = kstrdup(uuid, GFP_KERNEL);
 149                 if (!hc->uuid) {
 150                         kfree(hc->name);
 151                         kfree(hc);
 152                         return NULL;
 153                 }
 154         }
 155
 156         INIT_LIST_HEAD(&hc->name_list);
 157         INIT_LIST_HEAD(&hc->uuid_list);
 158         hc->md = md;
 159         hc->new_map = NULL;
 160         return hc;
 161 }
 162
 163 static void free_cell(struct hash_cell *hc)
 164 {
 165         if (hc) {
 166                 kfree(hc->name);
 167                 kfree(hc->uuid);
 168                 kfree(hc);
 169         }
 170 }
 171
 172 /*
 173  * The kdev_t and uuid of a device can never change once it is
 174  * initially inserted.
 175  */
 176 static int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md)
 177 {
 178         struct hash_cell *cell, *hc;
 179
 180         /*
 181          * Allocate the new cells.
 182          */
 183         cell = alloc_cell(name, uuid, md);
 184         if (!cell)
 185                 return -ENOMEM;
 186
 187         /*
 188          * Insert the cell into both hash tables.
 189          */
 190         down_write(&_hash_lock);
 191         hc = __get_name_cell(name);
 192         if (hc) {
 193                 dm_put(hc->md);
 194                 goto bad;
 195         }
 196
 197         list_add(&cell->name_list, _name_buckets + hash_str(name));
 198
 199         if (uuid) {
 200                 hc = __get_uuid_cell(uuid);
 201                 if (hc) {
 202                         list_del(&cell->name_list);
 203                         dm_put(hc->md);
 204                         goto bad;
 205                 }
 206                 list_add(&cell->uuid_list, _uuid_buckets + hash_str(uuid));
 207         }
 208         dm_get(md);
 209         dm_set_mdptr(md, cell);
 210         up_write(&_hash_lock);
 211
 212         return 0;
 213
 214  bad:
 215         up_write(&_hash_lock);
 216         free_cell(cell);
 217         return -EBUSY;
 218 }
 219
 220 static void __hash_remove(struct hash_cell *hc)
 221 {
 222         struct dm_table *table;
 223
 224         /* remove from the dev hash */
 225         list_del(&hc->uuid_list);
 226         list_del(&hc->name_list);
 227         dm_set_mdptr(hc->md, NULL);
 228
 229         table = dm_get_table(hc->md);
 230         if (table) {
 231                 dm_table_event(table);
 232                 dm_table_put(table);
 233         }
 234
 235         if (hc->new_map)
 236                 dm_table_destroy(hc->new_map);
 237         dm_put(hc->md);
 238         free_cell(hc);
 239 }
 240
 241 static void dm_hash_remove_all(int keep_open_devices)
 242 {
 243         int i, dev_skipped, dev_removed;
 244         struct hash_cell *hc;
 245         struct list_head *tmp, *n;
 246
 247         down_write(&_hash_lock);
 248
 249 retry:
 250         dev_skipped = dev_removed = 0;
 251         for (i = 0; i < NUM_BUCKETS; i++) {
 252                 list_for_each_safe (tmp, n, _name_buckets + i) {
 253                         hc = list_entry(tmp, struct hash_cell, name_list);
 254
 255                         if (keep_open_devices &&
 256                             dm_lock_for_deletion(hc->md)) {
 257                                 dev_skipped++;
 258                                 continue;
 259                         }
 260                         __hash_remove(hc);
 261                         dev_removed = 1;
 262                 }
 263         }
 264
 265         /*
 266          * Some mapped devices may be using other mapped devices, so if any
 267          * still exist, repeat until we make no further progress.
 268          */
 269         if (dev_skipped) {
 270                 if (dev_removed)
 271                         goto retry;
 272
 273                 DMWARN("remove_all left %d open device(s)", dev_skipped);
 274         }
 275
 276         up_write(&_hash_lock);
 277 }
 278
 279 static int dm_hash_rename(uint32_t cookie, const char *old, const char *new)
 280 {
 281         char *new_name, *old_name;
 282         struct hash_cell *hc;
 283         struct dm_table *table;
 284
 285         /*
 286          * duplicate new.
 287          */
 288         new_name = kstrdup(new, GFP_KERNEL);
 289         if (!new_name)
 290                 return -ENOMEM;
 291
 292         down_write(&_hash_lock);
 293
 294         /*
 295          * Is new free ?
 296          */
 297         hc = __get_name_cell(new);
 298         if (hc) {
 299                 DMWARN("asked to rename to an already existing name %s -> %s",
 300                        old, new);
 301                 dm_put(hc->md);
 302                 up_write(&_hash_lock);
 303                 kfree(new_name);
 304                 return -EBUSY;
 305         }
 306
 307         /*
 308          * Is there such a device as 'old' ?
 309          */
 310         hc = __get_name_cell(old);
 311         if (!hc) {
 312                 DMWARN("asked to rename a non existent device %s -> %s",
 313                        old, new);
 314                 up_write(&_hash_lock);
 315                 kfree(new_name);
 316                 return -ENXIO;
 317         }
 318
 319         /*
 320          * rename and move the name cell.
 321          */
 322         list_del(&hc->name_list);
 323         old_name = hc->name;
 324         hc->name = new_name;
 325         list_add(&hc->name_list, _name_buckets + hash_str(new_name));
 326
 327         /*
 328          * Wake up any dm event waiters.
 329          */
 330         table = dm_get_table(hc->md);
 331         if (table) {
 332                 dm_table_event(table);
 333                 dm_table_put(table);
 334         }
 335
 336         dm_kobject_uevent(hc->md, KOBJ_CHANGE, cookie);
 337
 338         dm_put(hc->md);
 339         up_write(&_hash_lock);
 340         kfree(old_name);
 341         return 0;
 342 }
 343
 344 /*-----------------------------------------------------------------
 345  * Implementation of the ioctl commands
 346  *---------------------------------------------------------------*/
 347 /*
 348  * All the ioctl commands get dispatched to functions with this
 349  * prototype.
 350  */
 351 typedef int (*ioctl_fn)(struct dm_ioctl *param, size_t param_size);
 352
 353 static int remove_all(struct dm_ioctl *param, size_t param_size)
 354 {
 355         dm_hash_remove_all(1);
 356         param->data_size = 0;
 357         return 0;
 358 }
 359
 360 /*
 361  * Round up the ptr to an 8-byte boundary.
 362  */
 363 #define ALIGN_MASK 7
 364 static inline void *align_ptr(void *ptr)
 365 {
 366         return (void *) (((size_t) (ptr + ALIGN_MASK)) & ~ALIGN_MASK);
 367 }
 368
 369 /*
 370  * Retrieves the data payload buffer from an already allocated
 371  * struct dm_ioctl.
 372  */
 373 static void *get_result_buffer(struct dm_ioctl *param, size_t param_size,
 374                                size_t *len)
 375 {
 376         param->data_start = align_ptr(param + 1) - (void *) param;
 377
 378         if (param->data_start < param_size)
 379                 *len = param_size - param->data_start;
 380         else
 381                 *len = 0;
 382
 383         return ((void *) param) + param->data_start;
 384 }
 385
 386 static int list_devices(struct dm_ioctl *param, size_t param_size)
 387 {
 388         unsigned int i;
 389         struct hash_cell *hc;
 390         size_t len, needed = 0;
 391         struct gendisk *disk;
 392         struct dm_name_list *nl, *old_nl = NULL;
 393
 394         down_write(&_hash_lock);
 395
 396         /*
 397          * Loop through all the devices working out how much
 398          * space we need.
 399          */
 400         for (i = 0; i < NUM_BUCKETS; i++) {
 401                 list_for_each_entry (hc, _name_buckets + i, name_list) {
 402                         needed += sizeof(struct dm_name_list);
 403                         needed += strlen(hc->name) + 1;
 404                         needed += ALIGN_MASK;
 405                 }
 406         }
 407
 408         /*
 409          * Grab our output buffer.
 410          */
 411         nl = get_result_buffer(param, param_size, &len);
 412         if (len < needed) {
 413                 param->flags |= DM_BUFFER_FULL_FLAG;
 414                 goto out;
 415         }
 416         param->data_size = param->data_start + needed;
 417
 418         nl->dev = 0;    /* Flags no data */
 419
 420         /*
 421          * Now loop through filling out the names.
 422          */
 423         for (i = 0; i < NUM_BUCKETS; i++) {
 424                 list_for_each_entry (hc, _name_buckets + i, name_list) {
 425                         if (old_nl)
 426                                 old_nl->next = (uint32_t) ((void *) nl -
 427                                                            (void *) old_nl);
 428                         disk = dm_disk(hc->md);
 429                         nl->dev = huge_encode_dev(disk_devt(disk));
 430                         nl->next = 0;
 431                         strcpy(nl->name, hc->name);
 432
 433                         old_nl = nl;
 434                         nl = align_ptr(((void *) ++nl) + strlen(hc->name) + 1);
 435                 }
 436         }
 437
 438  out:
 439         up_write(&_hash_lock);
 440         return 0;
 441 }
 442
 443 static void list_version_get_needed(struct target_type *tt, void *needed_param)
 444 {
 445     size_t *needed = needed_param;
 446
 447     *needed += sizeof(struct dm_target_versions);
 448     *needed += strlen(tt->name);
 449     *needed += ALIGN_MASK;
 450 }
 451
 452 static void list_version_get_info(struct target_type *tt, void *param)
 453 {
 454     struct vers_iter *info = param;
 455
 456     /* Check space - it might have changed since the first iteration */
 457     if ((char *)info->vers + sizeof(tt->version) + strlen(tt->name) + 1 >
 458         info->end) {
 459
 460         info->flags = DM_BUFFER_FULL_FLAG;
 461         return;
 462     }
 463
 464     if (info->old_vers)
 465         info->old_vers->next = (uint32_t) ((void *)info->vers -
 466                                            (void *)info->old_vers);
 467     info->vers->version[0] = tt->version[0];
 468     info->vers->version[1] = tt->version[1];
 469     info->vers->version[2] = tt->version[2];
 470     info->vers->next = 0;
 471     strcpy(info->vers->name, tt->name);
 472
 473     info->old_vers = info->vers;
 474     info->vers = align_ptr(((void *) ++info->vers) + strlen(tt->name) + 1);
 475 }
 476
 477 static int list_versions(struct dm_ioctl *param, size_t param_size)
 478 {
 479         size_t len, needed = 0;
 480         struct dm_target_versions *vers;
 481         struct vers_iter iter_info;
 482
 483         /*
 484          * Loop through all the devices working out how much
 485          * space we need.
 486          */
 487         dm_target_iterate(list_version_get_needed, &needed);
 488
 489         /*
 490          * Grab our output buffer.
 491          */
 492         vers = get_result_buffer(param, param_size, &len);
 493         if (len < needed) {
 494                 param->flags |= DM_BUFFER_FULL_FLAG;
 495                 goto out;
 496         }
 497         param->data_size = param->data_start + needed;
 498
 499         iter_info.param_size = param_size;
 500         iter_info.old_vers = NULL;
 501         iter_info.vers = vers;
 502         iter_info.flags = 0;
 503         iter_info.end = (char *)vers+len;
 504
 505         /*
 506          * Now loop through filling out the names & versions.
 507          */
 508         dm_target_iterate(list_version_get_info, &iter_info);
 509         param->flags |= iter_info.flags;
 510
 511  out:
 512         return 0;
 513 }
 514
 515
 516
 517 static int check_name(const char *name)
 518 {
 519         if (strchr(name, '/')) {
 520                 DMWARN("invalid device name");
 521                 return -EINVAL;
 522         }
 523
 524         return 0;
 525 }
 526
 527 /*
 528  * Fills in a dm_ioctl structure, ready for sending back to
 529  * userland.
 530  */
 531 static int __dev_status(struct mapped_device *md, struct dm_ioctl *param)
 532 {
 533         struct gendisk *disk = dm_disk(md);
 534         struct dm_table *table;
 535
 536         param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
 537                           DM_ACTIVE_PRESENT_FLAG);
 538
 539         if (dm_suspended(md))
 540                 param->flags |= DM_SUSPEND_FLAG;
 541
 542         param->dev = huge_encode_dev(disk_devt(disk));
 543
 544         /*
 545          * Yes, this will be out of date by the time it gets back
 546          * to userland, but it is still very useful for
 547          * debugging.
 548          */
 549         param->open_count = dm_open_count(md);
 550
 551         if (get_disk_ro(disk))
 552                 param->flags |= DM_READONLY_FLAG;
 553
 554         param->event_nr = dm_get_event_nr(md);
 555
 556         table = dm_get_table(md);
 557         if (table) {
 558                 param->flags |= DM_ACTIVE_PRESENT_FLAG;
 559                 param->target_count = dm_table_get_num_targets(table);
 560                 dm_table_put(table);
 561         } else
 562                 param->target_count = 0;
 563
 564         return 0;
 565 }
 566
 567 static int dev_create(struct dm_ioctl *param, size_t param_size)
 568 {
 569         int r, m = DM_ANY_MINOR;
 570         struct mapped_device *md;
 571
 572         r = check_name(param->name);
 573         if (r)
 574                 return r;
 575
 576         if (param->flags & DM_PERSISTENT_DEV_FLAG)
 577                 m = MINOR(huge_decode_dev(param->dev));
 578
 579         r = dm_create(m, &md);
 580         if (r)
 581                 return r;
 582
 583         r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md);
 584         if (r) {
 585                 dm_put(md);
 586                 return r;
 587         }
 588
 589         param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
 590
 591         r = __dev_status(md, param);
 592         dm_put(md);
 593
 594         return r;
 595 }
 596
 597 /*
 598  * Always use UUID for lookups if it's present, otherwise use name or dev.
 599  */
 600 static struct hash_cell *__find_device_hash_cell(struct dm_ioctl *param)
 601 {
 602         struct mapped_device *md;
 603         void *mdptr = NULL;
 604
 605         if (*param->uuid)
 606                 return __get_uuid_cell(param->uuid);
 607
 608         if (*param->name)
 609                 return __get_name_cell(param->name);
 610
 611         md = dm_get_md(huge_decode_dev(param->dev));
 612         if (!md)
 613                 goto out;
 614
 615         mdptr = dm_get_mdptr(md);
 616         if (!mdptr)
 617                 dm_put(md);
 618
 619 out:
 620         return mdptr;
 621 }
 622
 623 static struct mapped_device *find_device(struct dm_ioctl *param)
 624 {
 625         struct hash_cell *hc;
 626         struct mapped_device *md = NULL;
 627
 628         down_read(&_hash_lock);
 629         hc = __find_device_hash_cell(param);
 630         if (hc) {
 631                 md = hc->md;
 632
 633                 /*
 634                  * Sneakily write in both the name and the uuid
 635                  * while we have the cell.
 636                  */
 637                 strncpy(param->name, hc->name, sizeof(param->name));
 638                 if (hc->uuid)
 639                         strncpy(param->uuid, hc->uuid, sizeof(param->uuid)-1);
 640                 else
 641                         param->uuid[0] = '\0';
 642
 643                 if (hc->new_map)
 644                         param->flags |= DM_INACTIVE_PRESENT_FLAG;
 645                 else
 646                         param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
 647         }
 648         up_read(&_hash_lock);
 649
 650         return md;
 651 }
 652
 653 static int dev_remove(struct dm_ioctl *param, size_t param_size)
 654 {
 655         struct hash_cell *hc;
 656         struct mapped_device *md;
 657         int r;
 658
 659         down_write(&_hash_lock);
 660         hc = __find_device_hash_cell(param);
 661
 662         if (!hc) {
 663                 DMWARN("device doesn't appear to be in the dev hash table.");
 664                 up_write(&_hash_lock);
 665                 return -ENXIO;
 666         }
 667
 668         md = hc->md;
 669
 670         /*
 671          * Ensure the device is not open and nothing further can open it.
 672          */
 673         r = dm_lock_for_deletion(md);
 674         if (r) {
 675                 DMWARN("unable to remove open device %s", hc->name);
 676                 up_write(&_hash_lock);
 677                 dm_put(md);
 678                 return r;
 679         }
 680
 681         __hash_remove(hc);
 682         up_write(&_hash_lock);
 683
 684         dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr);
 685
 686         dm_put(md);
 687         param->data_size = 0;
 688         return 0;
 689 }
 690
 691 /*
 692  * Check a string doesn't overrun the chunk of
 693  * memory we copied from userland.
 694  */
 695 static int invalid_str(char *str, void *end)
 696 {
 697         while ((void *) str < end)
 698                 if (!*str++)
 699                         return 0;
 700
 701         return -EINVAL;
 702 }
 703
 704 static int dev_rename(struct dm_ioctl *param, size_t param_size)
 705 {
 706         int r;
 707         char *new_name = (char *) param + param->data_start;
 708
 709         if (new_name < param->data ||
 710             invalid_str(new_name, (void *) param + param_size) ||
 711             strlen(new_name) > DM_NAME_LEN - 1) {
 712                 DMWARN("Invalid new logical volume name supplied.");
 713                 return -EINVAL;
 714         }
 715
 716         r = check_name(new_name);
 717         if (r)
 718                 return r;
 719
 720         param->data_size = 0;
 721         return dm_hash_rename(param->event_nr, param->name, new_name);
 722 }
 723
 724 static int dev_set_geometry(struct dm_ioctl *param, size_t param_size)
 725 {
 726         int r = -EINVAL, x;
 727         struct mapped_device *md;
 728         struct hd_geometry geometry;
 729         unsigned long indata[4];
 730         char *geostr = (char *) param + param->data_start;
 731
 732         md = find_device(param);
 733         if (!md)
 734                 return -ENXIO;
 735
 736         if (geostr < param->data ||
 737             invalid_str(geostr, (void *) param + param_size)) {
 738                 DMWARN("Invalid geometry supplied.");
 739                 goto out;
 740         }
 741
 742         x = sscanf(geostr, "%lu %lu %lu %lu", indata,
 743                    indata + 1, indata + 2, indata + 3);
 744
 745         if (x != 4) {
 746                 DMWARN("Unable to interpret geometry settings.");
 747                 goto out;
 748         }
 749
 750         if (indata[0] > 65535 || indata[1] > 255 ||
 751             indata[2] > 255 || indata[3] > ULONG_MAX) {
 752                 DMWARN("Geometry exceeds range limits.");
 753                 goto out;
 754         }
 755
 756         geometry.cylinders = indata[0];
 757         geometry.heads = indata[1];
 758         geometry.sectors = indata[2];
 759         geometry.start = indata[3];
 760
 761         r = dm_set_geometry(md, &geometry);
 762         if (!r)
 763                 r = __dev_status(md, param);
 764
 765         param->data_size = 0;
 766
 767 out:
 768         dm_put(md);
 769         return r;
 770 }
 771
 772 static int do_suspend(struct dm_ioctl *param)
 773 {
 774         int r = 0;
 775         unsigned suspend_flags = DM_SUSPEND_LOCKFS_FLAG;
 776         struct mapped_device *md;
 777
 778         md = find_device(param);
 779         if (!md)
 780                 return -ENXIO;
 781
 782         if (param->flags & DM_SKIP_LOCKFS_FLAG)
 783                 suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
 784         if (param->flags & DM_NOFLUSH_FLAG)
 785                 suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
 786
 787         if (!dm_suspended(md))
 788                 r = dm_suspend(md, suspend_flags);
 789
 790         if (!r)
 791                 r = __dev_status(md, param);
 792
 793         dm_put(md);
 794         return r;
 795 }
 796
 797 static int do_resume(struct dm_ioctl *param)
 798 {
 799         int r = 0;
 800         unsigned suspend_flags = DM_SUSPEND_LOCKFS_FLAG;
 801         struct hash_cell *hc;
 802         struct mapped_device *md;
 803         struct dm_table *new_map;
 804
 805         down_write(&_hash_lock);
 806
 807         hc = __find_device_hash_cell(param);
 808         if (!hc) {
 809                 DMWARN("device doesn't appear to be in the dev hash table.");
 810                 up_write(&_hash_lock);
 811                 return -ENXIO;
 812         }
 813
 814         md = hc->md;
 815
 816         new_map = hc->new_map;
 817         hc->new_map = NULL;
 818         param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
 819
 820         up_write(&_hash_lock);
 821
 822         /* Do we need to load a new map ? */
 823         if (new_map) {
 824                 /* Suspend if it isn't already suspended */
 825                 if (param->flags & DM_SKIP_LOCKFS_FLAG)
 826                         suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
 827                 if (param->flags & DM_NOFLUSH_FLAG)
 828                         suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
 829                 if (!dm_suspended(md))
 830                         dm_suspend(md, suspend_flags);
 831
 832                 r = dm_swap_table(md, new_map);
 833                 if (r) {
 834                         dm_table_destroy(new_map);
 835                         dm_put(md);
 836                         return r;
 837                 }
 838
 839                 if (dm_table_get_mode(new_map) & FMODE_WRITE)
 840                         set_disk_ro(dm_disk(md), 0);
 841                 else
 842                         set_disk_ro(dm_disk(md), 1);
 843         }
 844
 845         if (dm_suspended(md))
 846                 r = dm_resume(md);
 847
 848
 849         if (!r) {
 850                 dm_kobject_uevent(md, KOBJ_CHANGE, param->event_nr);
 851                 r = __dev_status(md, param);
 852         }
 853
 854         dm_put(md);
 855         return r;
 856 }
 857
 858 /*
 859  * Set or unset the suspension state of a device.
 860  * If the device already is in the requested state we just return its status.
 861  */
 862 static int dev_suspend(struct dm_ioctl *param, size_t param_size)
 863 {
 864         if (param->flags & DM_SUSPEND_FLAG)
 865                 return do_suspend(param);
 866
 867         return do_resume(param);
 868 }
 869
 870 /*
 871  * Copies device info back to user space, used by
 872  * the create and info ioctls.
 873  */
 874 static int dev_status(struct dm_ioctl *param, size_t param_size)
 875 {
 876         int r;
 877         struct mapped_device *md;
 878
 879         md = find_device(param);
 880         if (!md)
 881                 return -ENXIO;
 882
 883         r = __dev_status(md, param);
 884         dm_put(md);
 885         return r;
 886 }
 887
 888 /*
 889  * Build up the status struct for each target
 890  */
 891 static void retrieve_status(struct dm_table *table,
 892                             struct dm_ioctl *param, size_t param_size)
 893 {
 894         unsigned int i, num_targets;
 895         struct dm_target_spec *spec;
 896         char *outbuf, *outptr;
 897         status_type_t type;
 898         size_t remaining, len, used = 0;
 899
 900         outptr = outbuf = get_result_buffer(param, param_size, &len);
 901
 902         if (param->flags & DM_STATUS_TABLE_FLAG)
 903                 type = STATUSTYPE_TABLE;
 904         else
 905                 type = STATUSTYPE_INFO;
 906
 907         /* Get all the target info */
 908         num_targets = dm_table_get_num_targets(table);
 909         for (i = 0; i < num_targets; i++) {
 910                 struct dm_target *ti = dm_table_get_target(table, i);
 911
 912                 remaining = len - (outptr - outbuf);
 913                 if (remaining <= sizeof(struct dm_target_spec)) {
 914                         param->flags |= DM_BUFFER_FULL_FLAG;
 915                         break;
 916                 }
 917
 918                 spec = (struct dm_target_spec *) outptr;
 919
 920                 spec->status = 0;
 921                 spec->sector_start = ti->begin;
 922                 spec->length = ti->len;
 923                 strncpy(spec->target_type, ti->type->name,
 924                         sizeof(spec->target_type));
 925
 926                 outptr += sizeof(struct dm_target_spec);
 927                 remaining = len - (outptr - outbuf);
 928                 if (remaining <= 0) {
 929                         param->flags |= DM_BUFFER_FULL_FLAG;
 930                         break;
 931                 }
 932
 933                 /* Get the status/table string from the target driver */
 934                 if (ti->type->status) {
 935                         if (ti->type->status(ti, type, outptr, remaining)) {
 936                                 param->flags |= DM_BUFFER_FULL_FLAG;
 937                                 break;
 938                         }
 939                 } else
 940                         outptr[0] = '\0';
 941
 942                 outptr += strlen(outptr) + 1;
 943                 used = param->data_start + (outptr - outbuf);
 944
 945                 outptr = align_ptr(outptr);
 946                 spec->next = outptr - outbuf;
 947         }
 948
 949         if (used)
 950                 param->data_size = used;
 951
 952         param->target_count = num_targets;
 953 }
 954
 955 /*
 956  * Wait for a device to report an event
 957  */
 958 static int dev_wait(struct dm_ioctl *param, size_t param_size)
 959 {
 960         int r;
 961         struct mapped_device *md;
 962         struct dm_table *table;
 963
 964         md = find_device(param);
 965         if (!md)
 966                 return -ENXIO;
 967
 968         /*
 969          * Wait for a notification event
 970          */
 971         if (dm_wait_event(md, param->event_nr)) {
 972                 r = -ERESTARTSYS;
 973                 goto out;
 974         }
 975
 976         /*
 977          * The userland program is going to want to know what
 978          * changed to trigger the event, so we may as well tell
 979          * him and save an ioctl.
 980          */
 981         r = __dev_status(md, param);
 982         if (r)
 983                 goto out;
 984
 985         table = dm_get_table(md);
 986         if (table) {
 987                 retrieve_status(table, param, param_size);
 988                 dm_table_put(table);
 989         }
 990
 991  out:
 992         dm_put(md);
 993         return r;
 994 }
 995
 996 static inline fmode_t get_mode(struct dm_ioctl *param)
 997 {
 998         fmode_t mode = FMODE_READ | FMODE_WRITE;
 999
1000         if (param->flags & DM_READONLY_FLAG)
1001                 mode = FMODE_READ;
1002
1003         return mode;
1004 }
1005
1006 static int next_target(struct dm_target_spec *last, uint32_t next, void *end,
1007                        struct dm_target_spec **spec, char **target_params)
1008 {
1009         *spec = (struct dm_target_spec *) ((unsigned char *) last + next);
1010         *target_params = (char *) (*spec + 1);
1011
1012         if (*spec < (last + 1))
1013                 return -EINVAL;
1014
1015         return invalid_str(*target_params, end);
1016 }
1017
1018 static int populate_table(struct dm_table *table,
1019                           struct dm_ioctl *param, size_t param_size)
1020 {
1021         int r;
1022         unsigned int i = 0;
1023         struct dm_target_spec *spec = (struct dm_target_spec *) param;
1024         uint32_t next = param->data_start;
1025         void *end = (void *) param + param_size;
1026         char *target_params;
1027
1028         if (!param->target_count) {
1029                 DMWARN("populate_table: no targets specified");
1030                 return -EINVAL;
1031         }
1032
1033         for (i = 0; i < param->target_count; i++) {
1034
1035                 r = next_target(spec, next, end, &spec, &target_params);
1036                 if (r) {
1037                         DMWARN("unable to find target");
1038                         return r;
1039                 }
1040
1041                 r = dm_table_add_target(table, spec->target_type,
1042                                         (sector_t) spec->sector_start,
1043                                         (sector_t) spec->length,
1044                                         target_params);
1045                 if (r) {
1046                         DMWARN("error adding target to table");
1047                         return r;
1048                 }
1049
1050                 next = spec->next;
1051         }
1052
1053         r = dm_table_set_type(table);
1054         if (r) {
1055                 DMWARN("unable to set table type");
1056                 return r;
1057         }
1058
1059         return dm_table_complete(table);
1060 }
1061
1062 static int table_prealloc_integrity(struct dm_table *t,
1063                                     struct mapped_device *md)
1064 {
1065         struct list_head *devices = dm_table_get_devices(t);
1066         struct dm_dev_internal *dd;
1067
1068         list_for_each_entry(dd, devices, list)
1069                 if (bdev_get_integrity(dd->dm_dev.bdev))
1070                         return blk_integrity_register(dm_disk(md), NULL);
1071
1072         return 0;
1073 }
1074
1075 static int table_load(struct dm_ioctl *param, size_t param_size)
1076 {
1077         int r;
1078         struct hash_cell *hc;
1079         struct dm_table *t;
1080         struct mapped_device *md;
1081
1082         md = find_device(param);
1083         if (!md)
1084                 return -ENXIO;
1085
1086         r = dm_table_create(&t, get_mode(param), param->target_count, md);
1087         if (r)
1088                 goto out;
1089
1090         r = populate_table(t, param, param_size);
1091         if (r) {
1092                 dm_table_destroy(t);
1093                 goto out;
1094         }
1095
1096         r = table_prealloc_integrity(t, md);
1097         if (r) {
1098                 DMERR("%s: could not register integrity profile.",
1099                       dm_device_name(md));
1100                 dm_table_destroy(t);
1101                 goto out;
1102         }
1103
1104         r = dm_table_alloc_md_mempools(t);
1105         if (r) {
1106                 DMWARN("unable to allocate mempools for this table");
1107                 dm_table_destroy(t);
1108                 goto out;
1109         }
1110
1111         down_write(&_hash_lock);
1112         hc = dm_get_mdptr(md);
1113         if (!hc || hc->md != md) {
1114                 DMWARN("device has been removed from the dev hash table.");
1115                 dm_table_destroy(t);
1116                 up_write(&_hash_lock);
1117                 r = -ENXIO;
1118                 goto out;
1119         }
1120
1121         if (hc->new_map)
1122                 dm_table_destroy(hc->new_map);
1123         hc->new_map = t;
1124         up_write(&_hash_lock);
1125
1126         param->flags |= DM_INACTIVE_PRESENT_FLAG;
1127         r = __dev_status(md, param);
1128
1129 out:
1130         dm_put(md);
1131
1132         return r;
1133 }
1134
1135 static int table_clear(struct dm_ioctl *param, size_t param_size)
1136 {
1137         int r;
1138         struct hash_cell *hc;
1139         struct mapped_device *md;
1140
1141         down_write(&_hash_lock);
1142
1143         hc = __find_device_hash_cell(param);
1144         if (!hc) {
1145                 DMWARN("device doesn't appear to be in the dev hash table.");
1146                 up_write(&_hash_lock);
1147                 return -ENXIO;
1148         }
1149
1150         if (hc->new_map) {
1151                 dm_table_destroy(hc->new_map);
1152                 hc->new_map = NULL;
1153         }
1154
1155         param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
1156
1157         r = __dev_status(hc->md, param);
1158         md = hc->md;
1159         up_write(&_hash_lock);
1160         dm_put(md);
1161         return r;
1162 }
1163
1164 /*
1165  * Retrieves a list of devices used by a particular dm device.
1166  */
1167 static void retrieve_deps(struct dm_table *table,
1168                           struct dm_ioctl *param, size_t param_size)
1169 {
1170         unsigned int count = 0;
1171         struct list_head *tmp;
1172         size_t len, needed;
1173         struct dm_dev_internal *dd;
1174         struct dm_target_deps *deps;
1175
1176         deps = get_result_buffer(param, param_size, &len);
1177
1178         /*
1179          * Count the devices.
1180          */
1181         list_for_each (tmp, dm_table_get_devices(table))
1182                 count++;
1183
1184         /*
1185          * Check we have enough space.
1186          */
1187         needed = sizeof(*deps) + (sizeof(*deps->dev) * count);
1188         if (len < needed) {
1189                 param->flags |= DM_BUFFER_FULL_FLAG;
1190                 return;
1191         }
1192
1193         /*
1194          * Fill in the devices.
1195          */
1196         deps->count = count;
1197         count = 0;
1198         list_for_each_entry (dd, dm_table_get_devices(table), list)
1199                 deps->dev[count++] = huge_encode_dev(dd->dm_dev.bdev->bd_dev);
1200
1201         param->data_size = param->data_start + needed;
1202 }
1203
1204 static int table_deps(struct dm_ioctl *param, size_t param_size)
1205 {
1206         int r = 0;
1207         struct mapped_device *md;
1208         struct dm_table *table;
1209
1210         md = find_device(param);
1211         if (!md)
1212                 return -ENXIO;
1213
1214         r = __dev_status(md, param);
1215         if (r)
1216                 goto out;
1217
1218         table = dm_get_table(md);
1219         if (table) {
1220                 retrieve_deps(table, param, param_size);
1221                 dm_table_put(table);
1222         }
1223
1224  out:
1225         dm_put(md);
1226         return r;
1227 }
1228
1229 /*
1230  * Return the status of a device as a text string for each
1231  * target.
1232  */
1233 static int table_status(struct dm_ioctl *param, size_t param_size)
1234 {
1235         int r;
1236         struct mapped_device *md;
1237         struct dm_table *table;
1238
1239         md = find_device(param);
1240         if (!md)
1241                 return -ENXIO;
1242
1243         r = __dev_status(md, param);
1244         if (r)
1245                 goto out;
1246
1247         table = dm_get_table(md);
1248         if (table) {
1249                 retrieve_status(table, param, param_size);
1250                 dm_table_put(table);
1251         }
1252
1253  out:
1254         dm_put(md);
1255         return r;
1256 }
1257
1258 /*
1259  * Pass a message to the target that's at the supplied device offset.
1260  */
1261 static int target_message(struct dm_ioctl *param, size_t param_size)
1262 {
1263         int r, argc;
1264         char **argv;
1265         struct mapped_device *md;
1266         struct dm_table *table;
1267         struct dm_target *ti;
1268         struct dm_target_msg *tmsg = (void *) param + param->data_start;
1269
1270         md = find_device(param);
1271         if (!md)
1272                 return -ENXIO;
1273
1274         r = __dev_status(md, param);
1275         if (r)
1276                 goto out;
1277
1278         if (tmsg < (struct dm_target_msg *) param->data ||
1279             invalid_str(tmsg->message, (void *) param + param_size)) {
1280                 DMWARN("Invalid target message parameters.");
1281                 r = -EINVAL;
1282                 goto out;
1283         }
1284
1285         r = dm_split_args(&argc, &argv, tmsg->message);
1286         if (r) {
1287                 DMWARN("Failed to split target message parameters");
1288                 goto out;
1289         }
1290
1291         table = dm_get_table(md);
1292         if (!table)
1293                 goto out_argv;
1294
1295         ti = dm_table_find_target(table, tmsg->sector);
1296         if (!dm_target_is_valid(ti)) {
1297                 DMWARN("Target message sector outside device.");
1298                 r = -EINVAL;
1299         } else if (ti->type->message)
1300                 r = ti->type->message(ti, argc, argv);
1301         else {
1302                 DMWARN("Target type does not support messages");
1303                 r = -EINVAL;
1304         }
1305
1306         dm_table_put(table);
1307  out_argv:
1308         kfree(argv);
1309  out:
1310         param->data_size = 0;
1311         dm_put(md);
1312         return r;
1313 }
1314
1315 /*-----------------------------------------------------------------
1316  * Implementation of open/close/ioctl on the special char
1317  * device.
1318  *---------------------------------------------------------------*/
1319 static ioctl_fn lookup_ioctl(unsigned int cmd)
1320 {
1321         static struct {
1322                 int cmd;
1323                 ioctl_fn fn;
1324         } _ioctls[] = {
1325                 {DM_VERSION_CMD, NULL}, /* version is dealt with elsewhere */
1326                 {DM_REMOVE_ALL_CMD, remove_all},
1327                 {DM_LIST_DEVICES_CMD, list_devices},
1328
1329                 {DM_DEV_CREATE_CMD, dev_create},
1330                 {DM_DEV_REMOVE_CMD, dev_remove},
1331                 {DM_DEV_RENAME_CMD, dev_rename},
1332                 {DM_DEV_SUSPEND_CMD, dev_suspend},
1333                 {DM_DEV_STATUS_CMD, dev_status},
1334                 {DM_DEV_WAIT_CMD, dev_wait},
1335
1336                 {DM_TABLE_LOAD_CMD, table_load},
1337                 {DM_TABLE_CLEAR_CMD, table_clear},
1338                 {DM_TABLE_DEPS_CMD, table_deps},
1339                 {DM_TABLE_STATUS_CMD, table_status},
1340
1341                 {DM_LIST_VERSIONS_CMD, list_versions},
1342
1343                 {DM_TARGET_MSG_CMD, target_message},
1344                 {DM_DEV_SET_GEOMETRY_CMD, dev_set_geometry}
1345         };
1346
1347         return (cmd >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[cmd].fn;
1348 }
1349
1350 /*
1351  * As well as checking the version compatibility this always
1352  * copies the kernel interface version out.
1353  */
1354 static int check_version(unsigned int cmd, struct dm_ioctl __user *user)
1355 {
1356         uint32_t version[3];
1357         int r = 0;
1358
1359         if (copy_from_user(version, user->version, sizeof(version)))
1360                 return -EFAULT;
1361
1362         if ((DM_VERSION_MAJOR != version[0]) ||
1363             (DM_VERSION_MINOR < version[1])) {
1364                 DMWARN("ioctl interface mismatch: "
1365                        "kernel(%u.%u.%u), user(%u.%u.%u), cmd(%d)",
1366                        DM_VERSION_MAJOR, DM_VERSION_MINOR,
1367                        DM_VERSION_PATCHLEVEL,
1368                        version[0], version[1], version[2], cmd);
1369                 r = -EINVAL;
1370         }
1371
1372         /*
1373          * Fill in the kernel version.
1374          */
1375         version[0] = DM_VERSION_MAJOR;
1376         version[1] = DM_VERSION_MINOR;
1377         version[2] = DM_VERSION_PATCHLEVEL;
1378         if (copy_to_user(user->version, version, sizeof(version)))
1379                 return -EFAULT;
1380
1381         return r;
1382 }
1383
1384 static void free_params(struct dm_ioctl *param)
1385 {
1386         vfree(param);
1387 }
1388
1389 static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl **param)
1390 {
1391         struct dm_ioctl tmp, *dmi;
1392
1393         if (copy_from_user(&tmp, user, sizeof(tmp) - sizeof(tmp.data)))
1394                 return -EFAULT;
1395
1396         if (tmp.data_size < (sizeof(tmp) - sizeof(tmp.data)))
1397                 return -EINVAL;
1398
1399         dmi = vmalloc(tmp.data_size);
1400         if (!dmi)
1401                 return -ENOMEM;
1402
1403         if (copy_from_user(dmi, user, tmp.data_size)) {
1404                 vfree(dmi);
1405                 return -EFAULT;
1406         }
1407
1408         *param = dmi;
1409         return 0;
1410 }
1411
1412 static int validate_params(uint cmd, struct dm_ioctl *param)
1413 {
1414         /* Always clear this flag */
1415         param->flags &= ~DM_BUFFER_FULL_FLAG;
1416
1417         /* Ignores parameters */
1418         if (cmd == DM_REMOVE_ALL_CMD ||
1419             cmd == DM_LIST_DEVICES_CMD ||
1420             cmd == DM_LIST_VERSIONS_CMD)
1421                 return 0;
1422
1423         if ((cmd == DM_DEV_CREATE_CMD)) {
1424                 if (!*param->name) {
1425                         DMWARN("name not supplied when creating device");
1426                         return -EINVAL;
1427                 }
1428         } else if ((*param->uuid && *param->name)) {
1429                 DMWARN("only supply one of name or uuid, cmd(%u)", cmd);
1430                 return -EINVAL;
1431         }
1432
1433         /* Ensure strings are terminated */
1434         param->name[DM_NAME_LEN - 1] = '\0';
1435         param->uuid[DM_UUID_LEN - 1] = '\0';
1436
1437         return 0;
1438 }
1439
1440 static int ctl_ioctl(uint command, struct dm_ioctl __user *user)
1441 {
1442         int r = 0;
1443         unsigned int cmd;
1444         struct dm_ioctl *uninitialized_var(param);
1445         ioctl_fn fn = NULL;
1446         size_t param_size;
1447
1448         /* only root can play with this */
1449         if (!capable(CAP_SYS_ADMIN))
1450                 return -EACCES;
1451
1452         if (_IOC_TYPE(command) != DM_IOCTL)
1453                 return -ENOTTY;
1454
1455         cmd = _IOC_NR(command);
1456
1457         /*
1458          * Check the interface version passed in.  This also
1459          * writes out the kernel's interface version.
1460          */
1461         r = check_version(cmd, user);
1462         if (r)
1463                 return r;
1464
1465         /*
1466          * Nothing more to do for the version command.
1467          */
1468         if (cmd == DM_VERSION_CMD)
1469                 return 0;
1470
1471         fn = lookup_ioctl(cmd);
1472         if (!fn) {
1473                 DMWARN("dm_ctl_ioctl: unknown command 0x%x", command);
1474                 return -ENOTTY;
1475         }
1476
1477         /*
1478          * Trying to avoid low memory issues when a device is
1479          * suspended.
1480          */
1481         current->flags |= PF_MEMALLOC;
1482
1483         /*
1484          * Copy the parameters into kernel space.
1485          */
1486         r = copy_params(user, &param);
1487
1488         current->flags &= ~PF_MEMALLOC;
1489
1490         if (r)
1491                 return r;
1492
1493         r = validate_params(cmd, param);
1494         if (r)
1495                 goto out;
1496
1497         param_size = param->data_size;
1498         param->data_size = sizeof(*param);
1499         r = fn(param, param_size);
1500
1501         /*
1502          * Copy the results back to userland.
1503          */
1504         if (!r && copy_to_user(user, param, param->data_size))
1505                 r = -EFAULT;
1506
1507  out:
1508         free_params(param);
1509         return r;
1510 }
1511
1512 static long dm_ctl_ioctl(struct file *file, uint command, ulong u)
1513 {
1514         return (long)ctl_ioctl(command, (struct dm_ioctl __user *)u);
1515 }
1516
1517 #ifdef CONFIG_COMPAT
1518 static long dm_compat_ctl_ioctl(struct file *file, uint command, ulong u)
1519 {
1520         return (long)dm_ctl_ioctl(file, command, (ulong) compat_ptr(u));
1521 }
1522 #else
1523 #define dm_compat_ctl_ioctl NULL
1524 #endif
1525
1526 static const struct file_operations _ctl_fops = {
1527         .unlocked_ioctl  = dm_ctl_ioctl,
1528         .compat_ioctl = dm_compat_ctl_ioctl,
1529         .owner   = THIS_MODULE,
1530 };
1531
1532 static struct miscdevice _dm_misc = {
1533         .minor          = MISC_DYNAMIC_MINOR,
1534         .name           = DM_NAME,
1535         .nodename       = "mapper/control",
1536         .fops           = &_ctl_fops
1537 };
1538
1539 /*
1540  * Create misc character device and link to DM_DIR/control.
1541  */
1542 int __init dm_interface_init(void)
1543 {
1544         int r;
1545
1546         r = dm_hash_init();
1547         if (r)
1548                 return r;
1549
1550         r = misc_register(&_dm_misc);
1551         if (r) {
1552                 DMERR("misc_register failed for control device");
1553                 dm_hash_exit();
1554                 return r;
1555         }
1556
1557         DMINFO("%d.%d.%d%s initialised: %s", DM_VERSION_MAJOR,
1558                DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL, DM_VERSION_EXTRA,
1559                DM_DRIVER_EMAIL);
1560         return 0;
1561 }
1562
1563 void dm_interface_exit(void)
1564 {
1565         if (misc_deregister(&_dm_misc) < 0)
1566                 DMERR("misc_deregister failed for control device");
1567
1568         dm_hash_exit();
1569 }
1570
1571 /**
1572  * dm_copy_name_and_uuid - Copy mapped device name & uuid into supplied buffers
1573  * @md: Pointer to mapped_device
1574  * @name: Buffer (size DM_NAME_LEN) for name
1575  * @uuid: Buffer (size DM_UUID_LEN) for uuid or empty string if uuid not defined
1576  */
1577 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
1578 {
1579         int r = 0;
1580         struct hash_cell *hc;
1581
1582         if (!md)
1583                 return -ENXIO;
1584
1585         dm_get(md);
1586         down_read(&_hash_lock);
1587         hc = dm_get_mdptr(md);
1588         if (!hc || hc->md != md) {
1589                 r = -ENXIO;
1590                 goto out;
1591         }
1592
1593         if (name)
1594                 strcpy(name, hc->name);
1595         if (uuid)
1596                 strcpy(uuid, hc->uuid ? : "");
1597
1598 out:
1599         up_read(&_hash_lock);
1600         dm_put(md);
1601
1602         return r;
1603 }