external/gpl2/lvm2/dist/lib/device/dev-cache.c

   1 /*      $NetBSD: dev-cache.c,v 1.3 2009/10/16 21:00:41 joerg Exp $      */
   2
   3 /*
   4  * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
   5  * Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
   6  *
   7  * This file is part of LVM2.
   8  *
   9  * This copyrighted material is made available to anyone wishing to use,
  10  * modify, copy, or redistribute it subject to the terms and conditions
  11  * of the GNU Lesser General Public License v.2.1.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public License
  14  * along with this program; if not, write to the Free Software Foundation,
  15  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  16  */
  17
  18 #include "lib.h"
  19 #include "dev-cache.h"
  20 #include "lvm-types.h"
  21 #include "btree.h"
  22 #include "filter.h"
  23 #include "filter-persistent.h"
  24 #include "toolcontext.h"
  25
  26 #include <unistd.h>
  27 #include <sys/param.h>
  28 #include <dirent.h>
  29
  30 #ifdef __NetBSD__
  31 #include "netbsd.h"
  32 #endif
  33
  34 struct dev_iter {
  35         struct btree_iter *current;
  36         struct dev_filter *filter;
  37 };
  38
  39 struct dir_list {
  40         struct dm_list list;
  41         char dir[0];
  42 };
  43
  44 static struct {
  45         struct dm_pool *mem;
  46         struct dm_hash_table *names;
  47         struct btree *devices;
  48         struct dm_regex *preferred_names_matcher;
  49
  50         int has_scanned;
  51         struct dm_list dirs;
  52         struct dm_list files;
  53
  54 } _cache;
  55
  56 #define _alloc(x) dm_pool_zalloc(_cache.mem, (x))
  57 #define _free(x) dm_pool_free(_cache.mem, (x))
  58 #define _strdup(x) dm_pool_strdup(_cache.mem, (x))
  59
  60 static int _insert(const char *path, int rec);
  61
  62 struct device *dev_create_file(const char *filename, struct device *dev,
  63                                struct str_list *alias, int use_malloc)
  64 {
  65         int allocate = !dev;
  66
  67         if (allocate) {
  68                 if (use_malloc) {
  69                         if (!(dev = dm_malloc(sizeof(*dev)))) {
  70                                 log_error("struct device allocation failed");
  71                                 return NULL;
  72                         }
  73                         if (!(alias = dm_malloc(sizeof(*alias)))) {
  74                                 log_error("struct str_list allocation failed");
  75                                 dm_free(dev);
  76                                 return NULL;
  77                         }
  78                         if (!(alias->str = dm_strdup(filename))) {
  79                                 log_error("filename strdup failed");
  80                                 dm_free(dev);
  81                                 dm_free(alias);
  82                                 return NULL;
  83                         }
  84                         dev->flags = DEV_ALLOCED;
  85                 } else {
  86                         if (!(dev = _alloc(sizeof(*dev)))) {
  87                                 log_error("struct device allocation failed");
  88                                 return NULL;
  89                         }
  90                         if (!(alias = _alloc(sizeof(*alias)))) {
  91                                 log_error("struct str_list allocation failed");
  92                                 _free(dev);
  93                                 return NULL;
  94                         }
  95                         if (!(alias->str = _strdup(filename))) {
  96                                 log_error("filename strdup failed");
  97                                 return NULL;
  98                         }
  99                 }
 100         } else if (!(alias->str = dm_strdup(filename))) {
 101                 log_error("filename strdup failed");
 102                 return NULL;
 103         }
 104
 105         dev->flags |= DEV_REGULAR;
 106         dm_list_init(&dev->aliases);
 107         dm_list_add(&dev->aliases, &alias->list);
 108         dev->end = UINT64_C(0);
 109         dev->dev = 0;
 110         dev->fd = -1;
 111         dev->open_count = 0;
 112         dev->block_size = -1;
 113         dev->read_ahead = -1;
 114         memset(dev->pvid, 0, sizeof(dev->pvid));
 115         dm_list_init(&dev->open_list);
 116
 117         return dev;
 118 }
 119
 120 static struct device *_dev_create(dev_t d)
 121 {
 122         struct device *dev;
 123
 124         if (!(dev = _alloc(sizeof(*dev)))) {
 125                 log_error("struct device allocation failed");
 126                 return NULL;
 127         }
 128         dev->flags = 0;
 129         dm_list_init(&dev->aliases);
 130         dev->dev = d;
 131         dev->fd = -1;
 132         dev->open_count = 0;
 133         dev->block_size = -1;
 134         dev->read_ahead = -1;
 135         dev->end = UINT64_C(0);
 136         memset(dev->pvid, 0, sizeof(dev->pvid));
 137         dm_list_init(&dev->open_list);
 138
 139         return dev;
 140 }
 141
 142 void dev_set_preferred_name(struct str_list *sl, struct device *dev)
 143 {
 144         /*
 145          * Don't interfere with ordering specified in config file.
 146          */
 147         if (_cache.preferred_names_matcher)
 148                 return;
 149
 150         log_debug("%s: New preferred name", sl->str);
 151         dm_list_del(&sl->list);
 152         dm_list_add_h(&dev->aliases, &sl->list);
 153 }
 154
 155 /* Return 1 if we prefer path1 else return 0 */
 156 static int _compare_paths(const char *path0, const char *path1)
 157 {
 158         int slash0 = 0, slash1 = 0;
 159         int m0, m1;
 160         const char *p;
 161         char p0[PATH_MAX], p1[PATH_MAX];
 162         char *s0, *s1;
 163         struct stat stat0, stat1;
 164
 165         /*
 166          * FIXME Better to compare patterns one-at-a-time against all names.
 167          */
 168         if (_cache.preferred_names_matcher) {
 169                 m0 = dm_regex_match(_cache.preferred_names_matcher, path0);
 170                 m1 = dm_regex_match(_cache.preferred_names_matcher, path1);
 171
 172                 if (m0 != m1) {
 173                         if (m0 < 0)
 174                                 return 1;
 175                         if (m1 < 0)
 176                                 return 0;
 177                         if (m0 < m1)
 178                                 return 1;
 179                         if (m1 < m0)
 180                                 return 0;
 181                 }
 182         }
 183
 184         /*
 185          * Built-in rules.
 186          */
 187
 188         /* Return the path with fewer slashes */
 189         for (p = path0; p++; p = (const char *) strchr(p, '/'))
 190                 slash0++;
 191
 192         for (p = path1; p++; p = (const char *) strchr(p, '/'))
 193                 slash1++;
 194
 195         if (slash0 < slash1)
 196                 return 0;
 197         if (slash1 < slash0)
 198                 return 1;
 199
 200         strncpy(p0, path0, PATH_MAX);
 201         strncpy(p1, path1, PATH_MAX);
 202         s0 = &p0[0] + 1;
 203         s1 = &p1[0] + 1;
 204
 205         /* We prefer symlinks - they exist for a reason!
 206          * So we prefer a shorter path before the first symlink in the name.
 207          * FIXME Configuration option to invert this? */
 208         while (s0) {
 209                 s0 = strchr(s0, '/');
 210                 s1 = strchr(s1, '/');
 211                 if (s0) {
 212                         *s0 = '\0';
 213                         *s1 = '\0';
 214                 }
 215                 if (lstat(p0, &stat0)) {
 216                         log_sys_very_verbose("lstat", p0);
 217                         return 1;
 218                 }
 219                 if (lstat(p1, &stat1)) {
 220                         log_sys_very_verbose("lstat", p1);
 221                         return 0;
 222                 }
 223                 if (S_ISLNK(stat0.st_mode) && !S_ISLNK(stat1.st_mode))
 224                         return 0;
 225                 if (!S_ISLNK(stat0.st_mode) && S_ISLNK(stat1.st_mode))
 226                         return 1;
 227                 if (s0) {
 228                         *s0++ = '/';
 229                         *s1++ = '/';
 230                 }
 231         }
 232
 233         /* ASCII comparison */
 234         if (strcmp(path0, path1) < 0)
 235                 return 0;
 236         else
 237                 return 1;
 238 }
 239
 240 static int _add_alias(struct device *dev, const char *path)
 241 {
 242         struct str_list *sl = _alloc(sizeof(*sl));
 243         struct str_list *strl;
 244         const char *oldpath;
 245         int prefer_old = 1;
 246
 247         if (!sl)
 248                 return_0;
 249
 250         /* Is name already there? */
 251         dm_list_iterate_items(strl, &dev->aliases) {
 252                 if (!strcmp(strl->str, path)) {
 253                         log_debug("%s: Already in device cache", path);
 254                         return 1;
 255                 }
 256         }
 257
 258         if (!(sl->str = dm_pool_strdup(_cache.mem, path)))
 259                 return_0;
 260
 261         if (!dm_list_empty(&dev->aliases)) {
 262                 oldpath = dm_list_item(dev->aliases.n, struct str_list)->str;
 263                 prefer_old = _compare_paths(path, oldpath);
 264                 log_debug("%s: Aliased to %s in device cache%s",
 265                           path, oldpath, prefer_old ? "" : " (preferred name)");
 266
 267         } else
 268                 log_debug("%s: Added to device cache", path);
 269
 270         if (prefer_old)
 271                 dm_list_add(&dev->aliases, &sl->list);
 272         else
 273                 dm_list_add_h(&dev->aliases, &sl->list);
 274
 275         return 1;
 276 }
 277
 278 /*
 279  * Either creates a new dev, or adds an alias to
 280  * an existing dev.
 281  */
 282 static int _insert_dev(const char *path, dev_t d)
 283 {
 284         struct device *dev;
 285         static dev_t loopfile_count = 0;
 286         int loopfile = 0;
 287
 288         /* Generate pretend device numbers for loopfiles */
 289         if (!d) {
 290                 if (dm_hash_lookup(_cache.names, path))
 291                         return 1;
 292                 d = ++loopfile_count;
 293                 loopfile = 1;
 294         }
 295
 296         /* is this device already registered ? */
 297         if (!(dev = (struct device *) btree_lookup(_cache.devices,
 298                                                    (uint32_t) d))) {
 299                 /* create new device */
 300                 if (loopfile) {
 301                         if (!(dev = dev_create_file(path, NULL, NULL, 0)))
 302                                 return_0;
 303                 } else if (!(dev = _dev_create(d)))
 304                         return_0;
 305
 306                 if (!(btree_insert(_cache.devices, (uint32_t) d, dev))) {
 307                         log_error("Couldn't insert device into binary tree.");
 308                         _free(dev);
 309                         return 0;
 310                 }
 311         }
 312
 313         if (!loopfile && !_add_alias(dev, path)) {
 314                 log_error("Couldn't add alias to dev cache.");
 315                 return 0;
 316         }
 317
 318         if (!dm_hash_insert(_cache.names, path, dev)) {
 319                 log_error("Couldn't add name to hash in dev cache.");
 320                 return 0;
 321         }
 322
 323         return 1;
 324 }
 325
 326 static char *_join(const char *dir, const char *name)
 327 {
 328         size_t len = strlen(dir) + strlen(name) + 2;
 329         char *r = dm_malloc(len);
 330         if (r)
 331                 snprintf(r, len, "%s/%s", dir, name);
 332
 333         return r;
 334 }
 335
 336 /*
 337  * Get rid of extra slashes in the path string.
 338  */
 339 static void _collapse_slashes(char *str)
 340 {
 341         char *ptr;
 342         int was_slash = 0;
 343
 344         for (ptr = str; *ptr; ptr++) {
 345                 if (*ptr == '/') {
 346                         if (was_slash)
 347                                 continue;
 348
 349                         was_slash = 1;
 350                 } else
 351                         was_slash = 0;
 352                 *str++ = *ptr;
 353         }
 354
 355         *str = *ptr;
 356 }
 357
 358 static int _insert_dir(const char *dir)
 359 {
 360         int n, dirent_count, r = 1;
 361         struct dirent **dirent;
 362         char *path;
 363
 364         dirent_count = scandir(dir, &dirent, NULL, alphasort);
 365         if (dirent_count > 0) {
 366                 for (n = 0; n < dirent_count; n++) {
 367                         if (dirent[n]->d_name[0] == '.') {
 368                                 free(dirent[n]);
 369                                 continue;
 370                         }
 371
 372                         if (!(path = _join(dir, dirent[n]->d_name)))
 373                                 return_0;
 374
 375                         _collapse_slashes(path);
 376                         r &= _insert(path, 1);
 377                         dm_free(path);
 378
 379                         free(dirent[n]);
 380                 }
 381                 free(dirent);
 382         }
 383
 384         return r;
 385 }
 386
 387 static int _insert_file(const char *path)
 388 {
 389         struct stat info;
 390
 391         if (stat(path, &info) < 0) {
 392                 log_sys_very_verbose("stat", path);
 393                 return 0;
 394         }
 395
 396         if (!S_ISREG(info.st_mode)) {
 397                 log_debug("%s: Not a regular file", path);
 398                 return 0;
 399         }
 400
 401         if (!_insert_dev(path, 0))
 402                 return_0;
 403
 404         return 1;
 405 }
 406
 407 static int _insert(const char *path, int rec)
 408 {
 409         struct stat info;
 410         int r = 0;
 411
 412         if (stat(path, &info) < 0) {
 413                 log_sys_very_verbose("stat", path);
 414                 return 0;
 415         }
 416
 417         if (S_ISDIR(info.st_mode)) {    /* add a directory */
 418                 /* check it's not a symbolic link */
 419                 if (lstat(path, &info) < 0) {
 420                         log_sys_very_verbose("lstat", path);
 421                         return 0;
 422                 }
 423
 424                 if (S_ISLNK(info.st_mode)) {
 425                         log_debug("%s: Symbolic link to directory", path);
 426                         return 0;
 427                 }
 428
 429                 if (rec)
 430                         r = _insert_dir(path);
 431
 432         } else {
 433                 /* add a device */
 434 #ifdef __NetBSD__
 435                 /*
 436                  * In NetBSD we have two different types of devices
 437                  * raw and block. I can insert only  existing
 438                  * raw and block device.
 439                  */
 440                 if (S_ISBLK(info.st_mode)) {
 441                         log_debug("%s: Not a raw device", path);
 442                         return_0;
 443                 }
 444                 if (nbsd_check_dev(MAJOR(info.st_rdev),path) < 0) {
 445                         log_debug("%s: Not a known raw device", path);
 446                         return_0;
 447                 }
 448 #else
 449                 if (!S_ISBLK(info.st_mode))
 450                         log_debug("%s: Not a block device", path);
 451 #endif
 452                 if (!_insert_dev(path, info.st_rdev)) {
 453                         return_0;
 454                 }
 455
 456                 r = 1;
 457         }
 458
 459         return r;
 460 }
 461
 462 static void _full_scan(int dev_scan)
 463 {
 464         struct dir_list *dl;
 465
 466         if (_cache.has_scanned && !dev_scan)
 467                 return;
 468
 469         dm_list_iterate_items(dl, &_cache.dirs)
 470                 _insert_dir(dl->dir);
 471
 472         dm_list_iterate_items(dl, &_cache.files)
 473                 _insert_file(dl->dir);
 474
 475         _cache.has_scanned = 1;
 476         init_full_scan_done(1);
 477 }
 478
 479 int dev_cache_has_scanned(void)
 480 {
 481         return _cache.has_scanned;
 482 }
 483
 484 void dev_cache_scan(int do_scan)
 485 {
 486         if (!do_scan)
 487                 _cache.has_scanned = 1;
 488         else
 489                 _full_scan(1);
 490 }
 491
 492 static int _init_preferred_names(struct cmd_context *cmd)
 493 {
 494         const struct config_node *cn;
 495         struct config_value *v;
 496         struct dm_pool *scratch = NULL;
 497         char **regex;
 498         unsigned count = 0;
 499         int i, r = 0;
 500
 501         _cache.preferred_names_matcher = NULL;
 502
 503         if (!(cn = find_config_tree_node(cmd, "devices/preferred_names")) ||
 504             cn->v->type == CFG_EMPTY_ARRAY) {
 505                 log_very_verbose("devices/preferred_names not found in config file: "
 506                                  "using built-in preferences");
 507                 return 1;
 508         }
 509
 510         for (v = cn->v; v; v = v->next) {
 511                 if (v->type != CFG_STRING) {
 512                         log_error("preferred_names patterns must be enclosed in quotes");
 513                         return 0;
 514                 }
 515
 516                 count++;
 517         }
 518
 519         if (!(scratch = dm_pool_create("preferred device name matcher", 1024)))
 520                 return_0;
 521
 522         if (!(regex = dm_pool_alloc(scratch, sizeof(*regex) * count))) {
 523                 log_error("Failed to allocate preferred device name "
 524                           "pattern list.");
 525                 goto out;
 526         }
 527
 528         for (v = cn->v, i = count - 1; v; v = v->next, i--) {
 529                 if (!(regex[i] = dm_pool_strdup(scratch, v->v.str))) {
 530                         log_error("Failed to allocate a preferred device name "
 531                                   "pattern.");
 532                         goto out;
 533                 }
 534         }
 535
 536         if (!(_cache.preferred_names_matcher =
 537                 dm_regex_create(_cache.mem,(const char **) regex, count))) {
 538                 log_error("Preferred device name pattern matcher creation failed.");
 539                 goto out;
 540         }
 541
 542         r = 1;
 543
 544 out:
 545         dm_pool_destroy(scratch);
 546
 547         return r;
 548 }
 549
 550 int dev_cache_init(struct cmd_context *cmd)
 551 {
 552         _cache.names = NULL;
 553         _cache.has_scanned = 0;
 554
 555         if (!(_cache.mem = dm_pool_create("dev_cache", 10 * 1024)))
 556                 return_0;
 557
 558         if (!(_cache.names = dm_hash_create(128))) {
 559                 dm_pool_destroy(_cache.mem);
 560                 _cache.mem = 0;
 561                 return_0;
 562         }
 563
 564         if (!(_cache.devices = btree_create(_cache.mem))) {
 565                 log_error("Couldn't create binary tree for dev-cache.");
 566                 goto bad;
 567         }
 568
 569         dm_list_init(&_cache.dirs);
 570         dm_list_init(&_cache.files);
 571
 572         if (!_init_preferred_names(cmd))
 573                 goto_bad;
 574
 575         return 1;
 576
 577       bad:
 578         dev_cache_exit();
 579         return 0;
 580 }
 581
 582 static void _check_closed(struct device *dev)
 583 {
 584         if (dev->fd >= 0)
 585                 log_error("Device '%s' has been left open.", dev_name(dev));
 586 }
 587
 588 static void _check_for_open_devices(void)
 589 {
 590         dm_hash_iter(_cache.names, (dm_hash_iterate_fn) _check_closed);
 591 }
 592
 593 void dev_cache_exit(void)
 594 {
 595         if (_cache.names)
 596                 _check_for_open_devices();
 597
 598         if (_cache.preferred_names_matcher)
 599                 _cache.preferred_names_matcher = NULL;
 600
 601         if (_cache.mem) {
 602                 dm_pool_destroy(_cache.mem);
 603                 _cache.mem = NULL;
 604         }
 605
 606         if (_cache.names) {
 607                 dm_hash_destroy(_cache.names);
 608                 _cache.names = NULL;
 609         }
 610
 611         _cache.devices = NULL;
 612         _cache.has_scanned = 0;
 613         dm_list_init(&_cache.dirs);
 614         dm_list_init(&_cache.files);
 615 }
 616
 617 int dev_cache_add_dir(const char *path)
 618 {
 619         struct dir_list *dl;
 620         struct stat st;
 621
 622         if (stat(path, &st)) {
 623                 log_error("Ignoring %s: %s", path, strerror(errno));
 624                 /* But don't fail */
 625                 return 1;
 626         }
 627
 628         if (!S_ISDIR(st.st_mode)) {
 629                 log_error("Ignoring %s: Not a directory", path);
 630                 return 1;
 631         }
 632
 633         if (!(dl = _alloc(sizeof(*dl) + strlen(path) + 1))) {
 634                 log_error("dir_list allocation failed");
 635                 return 0;
 636         }
 637
 638         strcpy(dl->dir, path);
 639         dm_list_add(&_cache.dirs, &dl->list);
 640         return 1;
 641 }
 642
 643 int dev_cache_add_loopfile(const char *path)
 644 {
 645         struct dir_list *dl;
 646         struct stat st;
 647
 648         if (stat(path, &st)) {
 649                 log_error("Ignoring %s: %s", path, strerror(errno));
 650                 /* But don't fail */
 651                 return 1;
 652         }
 653
 654         if (!S_ISREG(st.st_mode)) {
 655                 log_error("Ignoring %s: Not a regular file", path);
 656                 return 1;
 657         }
 658
 659         if (!(dl = _alloc(sizeof(*dl) + strlen(path) + 1))) {
 660                 log_error("dir_list allocation failed for file");
 661                 return 0;
 662         }
 663
 664         strcpy(dl->dir, path);
 665         dm_list_add(&_cache.files, &dl->list);
 666         return 1;
 667 }
 668
 669 /* Check cached device name is still valid before returning it */
 670 /* This should be a rare occurrence */
 671 /* set quiet if the cache is expected to be out-of-date */
 672 /* FIXME Make rest of code pass/cache struct device instead of dev_name */
 673 const char *dev_name_confirmed(struct device *dev, int quiet)
 674 {
 675         struct stat buf;
 676         const char *name;
 677         int r;
 678
 679         if ((dev->flags & DEV_REGULAR))
 680                 return dev_name(dev);
 681
 682         while ((r = stat(name = dm_list_item(dev->aliases.n,
 683                                           struct str_list)->str, &buf)) ||
 684                (buf.st_rdev != dev->dev)) {
 685                 if (r < 0) {
 686                         if (quiet)
 687                                 log_sys_debug("stat", name);
 688                         else
 689                                 log_sys_error("stat", name);
 690                 }
 691                 if (quiet)
 692                         log_debug("Path %s no longer valid for device(%d,%d)",
 693                                   name, (int) MAJOR(dev->dev),
 694                                   (int) MINOR(dev->dev));
 695                 else
 696                         log_error("Path %s no longer valid for device(%d,%d)",
 697                                   name, (int) MAJOR(dev->dev),
 698                                   (int) MINOR(dev->dev));
 699
 700                 /* Remove the incorrect hash entry */
 701                 dm_hash_remove(_cache.names, name);
 702
 703                 /* Leave list alone if there isn't an alternative name */
 704                 /* so dev_name will always find something to return. */
 705                 /* Otherwise add the name to the correct device. */
 706                 if (dm_list_size(&dev->aliases) > 1) {
 707                         dm_list_del(dev->aliases.n);
 708                         if (!r)
 709                                 _insert(name, 0);
 710                         continue;
 711                 }
 712
 713                 /* Scanning issues this inappropriately sometimes. */
 714                 log_debug("Aborting - please provide new pathname for what "
 715                           "used to be %s", name);
 716                 return NULL;
 717         }
 718
 719         return dev_name(dev);
 720 }
 721
 722 struct device *dev_cache_get(const char *name, struct dev_filter *f)
 723 {
 724         struct stat buf;
 725         struct device *d = (struct device *) dm_hash_lookup(_cache.names, name);
 726
 727         if (d && (d->flags & DEV_REGULAR))
 728                 return d;
 729
 730         /* If the entry's wrong, remove it */
 731         if (d && (stat(name, &buf) || (buf.st_rdev != d->dev))) {
 732                 dm_hash_remove(_cache.names, name);
 733                 d = NULL;
 734         }
 735
 736         if (!d) {
 737                 _insert(name, 0);
 738                 d = (struct device *) dm_hash_lookup(_cache.names, name);
 739                 if (!d) {
 740                         _full_scan(0);
 741                         d = (struct device *) dm_hash_lookup(_cache.names, name);
 742                 }
 743         }
 744
 745         return (d && (!f || (d->flags & DEV_REGULAR) ||
 746                       f->passes_filter(f, d))) ? d : NULL;
 747 }
 748
 749 struct dev_iter *dev_iter_create(struct dev_filter *f, int dev_scan)
 750 {
 751         struct dev_iter *di = dm_malloc(sizeof(*di));
 752
 753         if (!di) {
 754                 log_error("dev_iter allocation failed");
 755                 return NULL;
 756         }
 757
 758         if (dev_scan && !trust_cache()) {
 759                 /* Flag gets reset between each command */
 760                 if (!full_scan_done())
 761                         persistent_filter_wipe(f); /* Calls _full_scan(1) */
 762         } else
 763                 _full_scan(0);
 764
 765         di->current = btree_first(_cache.devices);
 766         di->filter = f;
 767
 768         return di;
 769 }
 770
 771 void dev_iter_destroy(struct dev_iter *iter)
 772 {
 773         dm_free(iter);
 774 }
 775
 776 static struct device *_iter_next(struct dev_iter *iter)
 777 {
 778         struct device *d = btree_get_data(iter->current);
 779         iter->current = btree_next(iter->current);
 780         return d;
 781 }
 782
 783 struct device *dev_iter_get(struct dev_iter *iter)
 784 {
 785         while (iter->current) {
 786                 struct device *d = _iter_next(iter);
 787                 if (!iter->filter || (d->flags & DEV_REGULAR) ||
 788                     iter->filter->passes_filter(iter->filter, d))
 789                         return d;
 790         }
 791
 792         return NULL;
 793 }
 794
 795 int dev_fd(struct device *dev)
 796 {
 797         return dev->fd;
 798 }
 799
 800 const char *dev_name(const struct device *dev)
 801 {
 802         return (dev) ? dm_list_item(dev->aliases.n, struct str_list)->str :
 803             "unknown device";
 804 }