drivers/md/dm-ioctl.c

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