sysfs.c

   1 /*
   2  * sysfs - extract md related information from sysfs.  Part of:
   3  * mdadm - manage Linux "md" devices aka RAID arrays.
   4  *
   5  * Copyright (C) 2006 Neil Brown <neilb@suse.de>
   6  *
   7  *
   8  *    This program is free software; you can redistribute it and/or modify
   9  *    it under the terms of the GNU General Public License as published by
  10  *    the Free Software Foundation; either version 2 of the License, or
  11  *    (at your option) any later version.
  12  *
  13  *    This program is distributed in the hope that it will be useful,
  14  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *    GNU General Public License for more details.
  17  *
  18  *    You should have received a copy of the GNU General Public License
  19  *    along with this program; if not, write to the Free Software
  20  *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  *
  22  *    Author: Neil Brown
  23  *    Email: <neilb@suse.de>
  24  */
  25
  26 #include        "mdadm.h"
  27 #include        <dirent.h>
  28 #include        <ctype.h>
  29
  30 int load_sys(char *path, char *buf)
  31 {
  32         int fd = open(path, O_RDONLY);
  33         int n;
  34         if (fd < 0)
  35                 return -1;
  36         n = read(fd, buf, 1024);
  37         close(fd);
  38         if (n <0 || n >= 1024)
  39                 return -1;
  40         buf[n] = 0;
  41         if (n && buf[n-1] == '\n')
  42                 buf[n-1] = 0;
  43         return 0;
  44 }
  45
  46 void sysfs_free(struct mdinfo *sra)
  47 {
  48         while (sra) {
  49                 struct mdinfo *sra2 = sra->next;
  50                 while (sra->devs) {
  51                         struct mdinfo *d = sra->devs;
  52                         sra->devs = d->next;
  53                         free(d);
  54                 }
  55                 free(sra);
  56                 sra = sra2;
  57         }
  58 }
  59
  60 int sysfs_open(int devnum, char *devname, char *attr)
  61 {
  62         char fname[50];
  63         int fd;
  64         char *mdname = devnum2devname(devnum);
  65
  66         if (!mdname)
  67                 return -1;
  68
  69         sprintf(fname, "/sys/block/%s/md/", mdname);
  70         if (devname) {
  71                 strcat(fname, devname);
  72                 strcat(fname, "/");
  73         }
  74         strcat(fname, attr);
  75         fd = open(fname, O_RDWR);
  76         if (fd < 0 && errno == EACCES)
  77                 fd = open(fname, O_RDONLY);
  78         free(mdname);
  79         return fd;
  80 }
  81
  82 void sysfs_init(struct mdinfo *mdi, int fd, int devnum)
  83 {
  84         if (fd >= 0) {
  85                 struct stat stb;
  86                 mdu_version_t vers;
  87                 if (fstat(fd, &stb))
  88                         return;
  89                 if (ioctl(fd, RAID_VERSION, &vers) != 0)
  90                         return;
  91                 if (major(stb.st_rdev) == MD_MAJOR)
  92                         sprintf(mdi->sys_name, "md%d", (int)minor(stb.st_rdev));
  93                 else if (major(stb.st_rdev) == get_mdp_major())
  94                         sprintf(mdi->sys_name, "md_d%d",
  95                                 (int)minor(stb.st_rdev)>>MdpMinorShift);
  96                 else {
  97                         /* must be an extended-minor partition. Look at the
  98                          * /sys/dev/block/%d:%d link which must look like
  99                          * ../../block/mdXXX/mdXXXpYY
 100                          */
 101                         char path[30];
 102                         char link[200];
 103                         char *cp;
 104                         int n;
 105                         sprintf(path, "/sys/dev/block/%d:%d", major(stb.st_rdev),
 106                                 minor(stb.st_rdev));
 107                         n = readlink(path, link, sizeof(link)-1);
 108                         if (n <= 0)
 109                                 return;
 110                         link[n] = 0;
 111                         cp = strrchr(link, '/');
 112                         if (cp) *cp = 0;
 113                         cp = strchr(link, '/');
 114                         if (cp && strncmp(cp, "/md", 3) == 0)
 115                                 strcpy(mdi->sys_name, cp+1);
 116                         else
 117                                 return;
 118                 }
 119         } else {
 120                 if (devnum >= 0)
 121                         sprintf(mdi->sys_name, "md%d", devnum);
 122                 else
 123                         sprintf(mdi->sys_name, "md_d%d",
 124                                 -1-devnum);
 125         }
 126 }
 127
 128 struct mdinfo *sysfs_read(int fd, int devnum, unsigned long options)
 129 {
 130         /* Longest possible name in sysfs, mounted at /sys, is
 131          *  /sys/block/md_dXXX/md/dev-XXXXX/block/dev
 132          *  /sys/block/md_dXXX/md/metadata_version
 133          * which is about 41 characters.  50 should do for now
 134          */
 135         char fname[50];
 136         char buf[1024];
 137         char *base;
 138         char *dbase;
 139         struct mdinfo *sra;
 140         struct mdinfo *dev;
 141         DIR *dir = NULL;
 142         struct dirent *de;
 143
 144         sra = malloc(sizeof(*sra));
 145         if (sra == NULL)
 146                 return sra;
 147         memset(sra, 0, sizeof(*sra));
 148         sysfs_init(sra, fd, devnum);
 149
 150         sprintf(fname, "/sys/block/%s/md/", sra->sys_name);
 151         base = fname + strlen(fname);
 152
 153         sra->devs = NULL;
 154         if (options & GET_VERSION) {
 155                 strcpy(base, "metadata_version");
 156                 if (load_sys(fname, buf))
 157                         goto abort;
 158                 if (strncmp(buf, "none", 4) == 0) {
 159                         sra->array.major_version =
 160                                 sra->array.minor_version = -1;
 161                         strcpy(sra->text_version, "");
 162                 } else if (strncmp(buf, "external:", 9) == 0) {
 163                         sra->array.major_version = -1;
 164                         sra->array.minor_version = -2;
 165                         strcpy(sra->text_version, buf+9);
 166                 } else {
 167                         sscanf(buf, "%d.%d",
 168                                &sra->array.major_version,
 169                                &sra->array.minor_version);
 170                         strcpy(sra->text_version, buf);
 171                 }
 172         }
 173         if (options & GET_LEVEL) {
 174                 strcpy(base, "level");
 175                 if (load_sys(fname, buf))
 176                         goto abort;
 177                 sra->array.level = map_name(pers, buf);
 178         }
 179         if (options & GET_LAYOUT) {
 180                 strcpy(base, "layout");
 181                 if (load_sys(fname, buf))
 182                         goto abort;
 183                 sra->array.layout = strtoul(buf, NULL, 0);
 184         }
 185         if (options & GET_DISKS) {
 186                 strcpy(base, "raid_disks");
 187                 if (load_sys(fname, buf))
 188                         goto abort;
 189                 sra->array.raid_disks = strtoul(buf, NULL, 0);
 190         }
 191         if (options & GET_DEGRADED) {
 192                 strcpy(base, "degraded");
 193                 if (load_sys(fname, buf))
 194                         goto abort;
 195                 sra->array.failed_disks = strtoul(buf, NULL, 0);
 196         }
 197         if (options & GET_COMPONENT) {
 198                 strcpy(base, "component_size");
 199                 if (load_sys(fname, buf))
 200                         goto abort;
 201                 sra->component_size = strtoull(buf, NULL, 0);
 202                 /* sysfs reports "K", but we want sectors */
 203                 sra->component_size *= 2;
 204         }
 205         if (options & GET_CHUNK) {
 206                 strcpy(base, "chunk_size");
 207                 if (load_sys(fname, buf))
 208                         goto abort;
 209                 sra->array.chunk_size = strtoul(buf, NULL, 0);
 210         }
 211         if (options & GET_CACHE) {
 212                 strcpy(base, "stripe_cache_size");
 213                 if (load_sys(fname, buf))
 214                         goto abort;
 215                 sra->cache_size = strtoul(buf, NULL, 0);
 216         }
 217         if (options & GET_MISMATCH) {
 218                 strcpy(base, "mismatch_cnt");
 219                 if (load_sys(fname, buf))
 220                         goto abort;
 221                 sra->mismatch_cnt = strtoul(buf, NULL, 0);
 222         }
 223         if (options & GET_SAFEMODE) {
 224                 int scale = 1;
 225                 int dot = 0;
 226                 int i;
 227                 unsigned long msec;
 228                 size_t len;
 229
 230                 strcpy(base, "safe_mode_delay");
 231                 if (load_sys(fname, buf))
 232                         goto abort;
 233
 234                 /* remove a period, and count digits after it */
 235                 len = strlen(buf);
 236                 for (i = 0; i < len; i++) {
 237                         if (dot) {
 238                                 if (isdigit(buf[i])) {
 239                                         buf[i-1] = buf[i];
 240                                         scale *= 10;
 241                                 }
 242                                 buf[i] = 0;
 243                         } else if (buf[i] == '.') {
 244                                 dot=1;
 245                                 buf[i] = 0;
 246                         }
 247                 }
 248                 msec = strtoul(buf, NULL, 10);
 249                 msec = (msec * 1000) / scale;
 250                 sra->safe_mode_delay = msec;
 251         }
 252
 253         if (! (options & GET_DEVS))
 254                 return sra;
 255
 256         /* Get all the devices as well */
 257         *base = 0;
 258         dir = opendir(fname);
 259         if (!dir)
 260                 goto abort;
 261         sra->array.spare_disks = 0;
 262
 263         while ((de = readdir(dir)) != NULL) {
 264                 char *ep;
 265                 if (de->d_ino == 0 ||
 266                     strncmp(de->d_name, "dev-", 4) != 0)
 267                         continue;
 268                 strcpy(base, de->d_name);
 269                 dbase = base + strlen(base);
 270                 *dbase++ = '/';
 271
 272                 dev = malloc(sizeof(*dev));
 273                 if (!dev)
 274                         goto abort;
 275
 276                 /* Always get slot, major, minor */
 277                 strcpy(dbase, "slot");
 278                 if (load_sys(fname, buf)) {
 279                         /* hmm... unable to read 'slot' maybe the device
 280                          * is going away?
 281                          */
 282                         strcpy(dbase, "block");
 283                         if (readlink(fname, buf, sizeof(buf)) < 0 &&
 284                             errno != ENAMETOOLONG) {
 285                                 /* ...yup device is gone */
 286                                 free(dev);
 287                                 continue;
 288                         } else {
 289                                 /* slot is unreadable but 'block' link
 290                                  * still intact... something bad is happening
 291                                  * so abort
 292                                  */
 293                                 free(dev);
 294                                 goto abort;
 295                         }
 296
 297                 }
 298                 dev->next = sra->devs;
 299                 sra->devs = dev;
 300
 301                 strcpy(dev->sys_name, de->d_name);
 302                 dev->disk.raid_disk = strtoul(buf, &ep, 10);
 303                 if (*ep) dev->disk.raid_disk = -1;
 304
 305                 strcpy(dbase, "block/dev");
 306                 if (load_sys(fname, buf))
 307                         goto abort;
 308                 sscanf(buf, "%d:%d", &dev->disk.major, &dev->disk.minor);
 309
 310                 if (options & GET_OFFSET) {
 311                         strcpy(dbase, "offset");
 312                         if (load_sys(fname, buf))
 313                                 goto abort;
 314                         dev->data_offset = strtoull(buf, NULL, 0);
 315                 }
 316                 if (options & GET_SIZE) {
 317                         strcpy(dbase, "size");
 318                         if (load_sys(fname, buf))
 319                                 goto abort;
 320                         dev->component_size = strtoull(buf, NULL, 0) * 2;
 321                 }
 322                 if (options & GET_STATE) {
 323                         dev->disk.state = 0;
 324                         strcpy(dbase, "state");
 325                         if (load_sys(fname, buf))
 326                                 goto abort;
 327                         if (strstr(buf, "in_sync"))
 328                                 dev->disk.state |= (1<<MD_DISK_SYNC);
 329                         if (strstr(buf, "faulty"))
 330                                 dev->disk.state |= (1<<MD_DISK_FAULTY);
 331                         if (dev->disk.state == 0)
 332                                 sra->array.spare_disks++;
 333                 }
 334                 if (options & GET_ERROR) {
 335                         strcpy(buf, "errors");
 336                         if (load_sys(fname, buf))
 337                                 goto abort;
 338                         dev->errors = strtoul(buf, NULL, 0);
 339                 }
 340         }
 341         closedir(dir);
 342         return sra;
 343
 344  abort:
 345         if (dir)
 346                 closedir(dir);
 347         sysfs_free(sra);
 348         return NULL;
 349 }
 350
 351 int sysfs_attr_match(const char *attr, const char *str)
 352 {
 353         /* See if attr, read from a sysfs file, matches
 354          * str.  They must either be the same, or attr can
 355          * have a trailing newline or comma
 356          */
 357         while (*attr && *str && *attr == *str) {
 358                 attr++;
 359                 str++;
 360         }
 361
 362         if (*str || (*attr && *attr != ',' && *attr != '\n'))
 363                 return 0;
 364         return 1;
 365 }
 366
 367 int sysfs_match_word(const char *word, char **list)
 368 {
 369         int n;
 370         for (n=0; list[n]; n++)
 371                 if (sysfs_attr_match(word, list[n]))
 372                         break;
 373         return n;
 374 }
 375
 376 unsigned long long get_component_size(int fd)
 377 {
 378         /* Find out the component size of the array.
 379          * We cannot trust GET_ARRAY_INFO ioctl as it's
 380          * size field is only 32bits.
 381          * So look in /sys/block/mdXXX/md/component_size
 382          *
 383          * This returns in units of sectors.
 384          */
 385         struct stat stb;
 386         char fname[50];
 387         int n;
 388         if (fstat(fd, &stb)) return 0;
 389         if (major(stb.st_rdev) != get_mdp_major())
 390                 sprintf(fname, "/sys/block/md%d/md/component_size",
 391                         (int)minor(stb.st_rdev));
 392         else
 393                 sprintf(fname, "/sys/block/md_d%d/md/component_size",
 394                         (int)minor(stb.st_rdev)>>MdpMinorShift);
 395         fd = open(fname, O_RDONLY);
 396         if (fd < 0)
 397                 return 0;
 398         n = read(fd, fname, sizeof(fname));
 399         close(fd);
 400         if (n == sizeof(fname))
 401                 return 0;
 402         fname[n] = 0;
 403         return strtoull(fname, NULL, 10) * 2;
 404 }
 405
 406 int sysfs_set_str(struct mdinfo *sra, struct mdinfo *dev,
 407                   char *name, char *val)
 408 {
 409         char fname[50];
 410         int n;
 411         int fd;
 412
 413         sprintf(fname, "/sys/block/%s/md/%s/%s",
 414                 sra->sys_name, dev?dev->sys_name:"", name);
 415         fd = open(fname, O_WRONLY);
 416         if (fd < 0)
 417                 return -1;
 418         n = write(fd, val, strlen(val));
 419         close(fd);
 420         if (n != strlen(val)) {
 421                 dprintf(Name ": failed to write '%s' to '%s' (%s)\n",
 422                         val, fname, strerror(errno));
 423                 return -1;
 424         }
 425         return 0;
 426 }
 427
 428 int sysfs_set_num(struct mdinfo *sra, struct mdinfo *dev,
 429                   char *name, unsigned long long val)
 430 {
 431         char valstr[50];
 432         sprintf(valstr, "%llu", val);
 433         return sysfs_set_str(sra, dev, name, valstr);
 434 }
 435
 436 int sysfs_get_ll(struct mdinfo *sra, struct mdinfo *dev,
 437                        char *name, unsigned long long *val)
 438 {
 439         char fname[50];
 440         char buf[50];
 441         int n;
 442         int fd;
 443         char *ep;
 444         sprintf(fname, "/sys/block/%s/md/%s/%s",
 445                 sra->sys_name, dev?dev->sys_name:"", name);
 446         fd = open(fname, O_RDONLY);
 447         if (fd < 0)
 448                 return -1;
 449         n = read(fd, buf, sizeof(buf));
 450         close(fd);
 451         if (n <= 0)
 452                 return -1;
 453         buf[n] = 0;
 454         *val = strtoull(buf, &ep, 0);
 455         if (ep == buf || (*ep != 0 && *ep != '\n' && *ep != ' '))
 456                 return -1;
 457         return 0;
 458 }
 459
 460 int sysfs_set_safemode(struct mdinfo *sra, unsigned long ms)
 461 {
 462         unsigned long sec;
 463         unsigned long msec;
 464         char delay[30];
 465
 466         sec = ms / 1000;
 467         msec = ms % 1000;
 468
 469         sprintf(delay, "%ld.%03ld\n", sec, msec);
 470         /*             this '\n' ^ needed for kernels older than 2.6.28 */
 471         return sysfs_set_str(sra, NULL, "safe_mode_delay", delay);
 472 }
 473
 474 int sysfs_set_array(struct mdinfo *info, int vers)
 475 {
 476         int rv = 0;
 477         char ver[100];
 478
 479         ver[0] = 0;
 480         if (info->array.major_version == -1 &&
 481             info->array.minor_version == -2) {
 482                 strcat(strcpy(ver, "external:"), info->text_version);
 483
 484                 if ((vers % 100) < 2 ||
 485                     sysfs_set_str(info, NULL, "metadata_version",
 486                                   ver) < 0) {
 487                         fprintf(stderr, Name ": This kernel does not "
 488                                 "support external metadata.\n");
 489                         return 1;
 490                 }
 491         }
 492         if (info->array.level < 0)
 493                 return 0; /* FIXME */
 494         rv |= sysfs_set_str(info, NULL, "level",
 495                             map_num(pers, info->array.level));
 496         rv |= sysfs_set_num(info, NULL, "raid_disks", info->array.raid_disks);
 497         rv |= sysfs_set_num(info, NULL, "chunk_size", info->array.chunk_size);
 498         rv |= sysfs_set_num(info, NULL, "layout", info->array.layout);
 499         rv |= sysfs_set_num(info, NULL, "component_size", info->component_size/2);
 500         if (info->array.level > 0)
 501                 rv |= sysfs_set_num(info, NULL, "resync_start", info->resync_start);
 502         return rv;
 503 }
 504
 505 int sysfs_add_disk(struct mdinfo *sra, struct mdinfo *sd)
 506 {
 507         char dv[100];
 508         char nm[100];
 509         char *dname;
 510         int rv;
 511
 512         sprintf(dv, "%d:%d", sd->disk.major, sd->disk.minor);
 513         rv = sysfs_set_str(sra, NULL, "new_dev", dv);
 514         if (rv)
 515                 return rv;
 516
 517         memset(nm, 0, sizeof(nm));
 518         sprintf(dv, "/sys/dev/block/%d:%d", sd->disk.major, sd->disk.minor);
 519         rv = readlink(dv, nm, sizeof(nm));
 520         if (rv <= 0)
 521                 return -1;
 522         nm[rv] = '\0';
 523         dname = strrchr(nm, '/');
 524         if (dname) dname++;
 525         strcpy(sd->sys_name, "dev-");
 526         strcpy(sd->sys_name+4, dname);
 527
 528         rv = sysfs_set_num(sra, sd, "offset", sd->data_offset);
 529         rv |= sysfs_set_num(sra, sd, "size", (sd->component_size+1) / 2);
 530         if (sra->array.level != LEVEL_CONTAINER) {
 531                 rv |= sysfs_set_num(sra, sd, "slot", sd->disk.raid_disk);
 532 //              rv |= sysfs_set_str(sra, sd, "state", "in_sync");
 533         }
 534         return rv;
 535 }
 536
 537 #if 0
 538 int sysfs_disk_to_sg(int fd)
 539 {
 540         /* from an open block device, try find and open its corresponding
 541          * scsi_generic interface
 542          */
 543         struct stat st;
 544         char path[256];
 545         char sg_path[256];
 546         char sg_major_minor[8];
 547         char *c;
 548         DIR *dir;
 549         struct dirent *de;
 550         int major, minor, rv;
 551
 552         if (fstat(fd, &st))
 553                 return -1;
 554
 555         snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/device",
 556                  major(st.st_rdev), minor(st.st_rdev));
 557
 558         dir = opendir(path);
 559         if (!dir)
 560                 return -1;
 561
 562         de = readdir(dir);
 563         while (de) {
 564                 if (strncmp("scsi_generic:", de->d_name,
 565                             strlen("scsi_generic:")) == 0)
 566                         break;
 567                 de = readdir(dir);
 568         }
 569         closedir(dir);
 570
 571         if (!de)
 572                 return -1;
 573
 574         snprintf(sg_path, sizeof(sg_path), "%s/%s/dev", path, de->d_name);
 575         fd = open(sg_path, O_RDONLY);
 576         if (fd < 0)
 577                 return fd;
 578
 579         rv = read(fd, sg_major_minor, sizeof(sg_major_minor));
 580         close(fd);
 581         if (rv < 0)
 582                 return -1;
 583         else
 584                 sg_major_minor[rv - 1] = '\0';
 585
 586         c = strchr(sg_major_minor, ':');
 587         *c = '\0';
 588         c++;
 589         major = strtol(sg_major_minor, NULL, 10);
 590         minor = strtol(c, NULL, 10);
 591         snprintf(path, sizeof(path), "/dev/.tmp.md.%d:%d:%d",
 592                  (int) getpid(), major, minor);
 593         if (mknod(path, S_IFCHR|0600, makedev(major, minor))==0) {
 594                         fd = open(path, O_RDONLY);
 595                         unlink(path);
 596                         return fd;
 597         }
 598
 599         return -1;
 600 }
 601 #endif
 602
 603 int sysfs_disk_to_scsi_id(int fd, __u32 *id)
 604 {
 605         /* from an open block device, try to retrieve it scsi_id */
 606         struct stat st;
 607         char path[256];
 608         char *c1, *c2;
 609         DIR *dir;
 610         struct dirent *de;
 611
 612         if (fstat(fd, &st))
 613                 return 1;
 614
 615         snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/device",
 616                  major(st.st_rdev), minor(st.st_rdev));
 617
 618         dir = opendir(path);
 619         if (!dir)
 620                 return 1;
 621
 622         de = readdir(dir);
 623         while (de) {
 624                 if (strncmp("scsi_disk:", de->d_name,
 625                             strlen("scsi_disk:")) == 0)
 626                         break;
 627                 de = readdir(dir);
 628         }
 629         closedir(dir);
 630
 631         if (!de)
 632                 return 1;
 633
 634         c1 = strchr(de->d_name, ':');
 635         c1++;
 636         c2 = strchr(c1, ':');
 637         *c2 = '\0';
 638         *id = strtol(c1, NULL, 10) << 24; /* host */
 639         c1 = c2 + 1;
 640         c2 = strchr(c1, ':');
 641         *c2 = '\0';
 642         *id |= strtol(c1, NULL, 10) << 16; /* channel */
 643         c1 = c2 + 1;
 644         c2 = strchr(c1, ':');
 645         *c2 = '\0';
 646         *id |= strtol(c1, NULL, 10) << 8; /* lun */
 647         c1 = c2 + 1;
 648         *id |= strtol(c1, NULL, 10); /* id */
 649
 650         return 0;
 651 }
 652
 653
 654 int sysfs_unique_holder(int devnum, long rdev)
 655 {
 656         /* Check that devnum is a holder of rdev,
 657          * and is the only holder.
 658          * we should be locked against races by
 659          * an O_EXCL on devnum
 660          */
 661         DIR *dir;
 662         struct dirent *de;
 663         char dirname[100];
 664         char l;
 665         int found = 0;
 666         sprintf(dirname, "/sys/dev/block/%d:%d/holders",
 667                 major(rdev), minor(rdev));
 668         dir = opendir(dirname);
 669         errno = ENOENT;
 670         if (!dir)
 671                 return 0;
 672         l = strlen(dirname);
 673         while ((de = readdir(dir)) != NULL) {
 674                 char buf[10];
 675                 int n;
 676                 int mj, mn;
 677                 char c;
 678                 int fd;
 679
 680                 if (de->d_ino == 0)
 681                         continue;
 682                 if (de->d_name[0] == '.')
 683                         continue;
 684                 strcpy(dirname+l, "/");
 685                 strcat(dirname+l, de->d_name);
 686                 strcat(dirname+l, "/dev");
 687                 fd = open(dirname, O_RDONLY);
 688                 if (fd < 0) {
 689                         errno = ENOENT;
 690                         break;
 691                 }
 692                 n = read(fd, buf, sizeof(buf)-1);
 693                 close(fd);
 694                 buf[n] = 0;
 695                 if (sscanf(buf, "%d:%d%c", &mj, &mn, &c) != 3 ||
 696                     c != '\n') {
 697                         errno = ENOENT;
 698                         break;
 699                 }
 700                 if (mj != MD_MAJOR)
 701                         mn = -1-(mn>>6);
 702
 703                 if (devnum != mn) {
 704                         errno = EEXIST;
 705                         break;
 706                 }
 707                 found = 1;
 708         }
 709         closedir(dir);
 710         if (de)
 711                 return 0;
 712         else
 713                 return found;
 714 }