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) 2006-2009 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         mdi->sys_name[0] = 0;
  85         if (fd >= 0) {
  86                 mdu_version_t vers;
  87                 if (ioctl(fd, RAID_VERSION, &vers) != 0)
  88                         return;
  89                 devnum = fd2devnum(fd);
  90         }
  91         if (devnum == NoMdDev)
  92                 return;
  93         fmt_devname(mdi->sys_name, devnum);
  94 }
  95
  96
  97 struct mdinfo *sysfs_read(int fd, int devnum, unsigned long options)
  98 {
  99         char fname[PATH_MAX];
 100         char buf[PATH_MAX];
 101         char *base;
 102         char *dbase;
 103         struct mdinfo *sra;
 104         struct mdinfo *dev;
 105         DIR *dir = NULL;
 106         struct dirent *de;
 107
 108         sra = xcalloc(1, sizeof(*sra));
 109         sysfs_init(sra, fd, devnum);
 110         if (sra->sys_name[0] == 0) {
 111                 free(sra);
 112                 return NULL;
 113         }
 114
 115         sprintf(fname, "/sys/block/%s/md/", sra->sys_name);
 116         base = fname + strlen(fname);
 117
 118         sra->devs = NULL;
 119         if (options & GET_VERSION) {
 120                 strcpy(base, "metadata_version");
 121                 if (load_sys(fname, buf))
 122                         goto abort;
 123                 if (strncmp(buf, "none", 4) == 0) {
 124                         sra->array.major_version =
 125                                 sra->array.minor_version = -1;
 126                         strcpy(sra->text_version, "");
 127                 } else if (strncmp(buf, "external:", 9) == 0) {
 128                         sra->array.major_version = -1;
 129                         sra->array.minor_version = -2;
 130                         strcpy(sra->text_version, buf+9);
 131                 } else {
 132                         sscanf(buf, "%d.%d",
 133                                &sra->array.major_version,
 134                                &sra->array.minor_version);
 135                         strcpy(sra->text_version, buf);
 136                 }
 137         }
 138         if (options & GET_LEVEL) {
 139                 strcpy(base, "level");
 140                 if (load_sys(fname, buf))
 141                         goto abort;
 142                 sra->array.level = map_name(pers, buf);
 143         }
 144         if (options & GET_LAYOUT) {
 145                 strcpy(base, "layout");
 146                 if (load_sys(fname, buf))
 147                         goto abort;
 148                 sra->array.layout = strtoul(buf, NULL, 0);
 149         }
 150         if (options & GET_DISKS) {
 151                 strcpy(base, "raid_disks");
 152                 if (load_sys(fname, buf))
 153                         goto abort;
 154                 sra->array.raid_disks = strtoul(buf, NULL, 0);
 155         }
 156         if (options & GET_DEGRADED) {
 157                 strcpy(base, "degraded");
 158                 if (load_sys(fname, buf))
 159                         goto abort;
 160                 sra->array.failed_disks = strtoul(buf, NULL, 0);
 161         }
 162         if (options & GET_COMPONENT) {
 163                 strcpy(base, "component_size");
 164                 if (load_sys(fname, buf))
 165                         goto abort;
 166                 sra->component_size = strtoull(buf, NULL, 0);
 167                 /* sysfs reports "K", but we want sectors */
 168                 sra->component_size *= 2;
 169         }
 170         if (options & GET_CHUNK) {
 171                 strcpy(base, "chunk_size");
 172                 if (load_sys(fname, buf))
 173                         goto abort;
 174                 sra->array.chunk_size = strtoul(buf, NULL, 0);
 175         }
 176         if (options & GET_CACHE) {
 177                 strcpy(base, "stripe_cache_size");
 178                 if (load_sys(fname, buf))
 179                         goto abort;
 180                 sra->cache_size = strtoul(buf, NULL, 0);
 181         }
 182         if (options & GET_MISMATCH) {
 183                 strcpy(base, "mismatch_cnt");
 184                 if (load_sys(fname, buf))
 185                         goto abort;
 186                 sra->mismatch_cnt = strtoul(buf, NULL, 0);
 187         }
 188         if (options & GET_SAFEMODE) {
 189                 int scale = 1;
 190                 int dot = 0;
 191                 unsigned i;
 192                 unsigned long msec;
 193                 size_t len;
 194
 195                 strcpy(base, "safe_mode_delay");
 196                 if (load_sys(fname, buf))
 197                         goto abort;
 198
 199                 /* remove a period, and count digits after it */
 200                 len = strlen(buf);
 201                 for (i = 0; i < len; i++) {
 202                         if (dot) {
 203                                 if (isdigit(buf[i])) {
 204                                         buf[i-1] = buf[i];
 205                                         scale *= 10;
 206                                 }
 207                                 buf[i] = 0;
 208                         } else if (buf[i] == '.') {
 209                                 dot=1;
 210                                 buf[i] = 0;
 211                         }
 212                 }
 213                 msec = strtoul(buf, NULL, 10);
 214                 msec = (msec * 1000) / scale;
 215                 sra->safe_mode_delay = msec;
 216         }
 217         if (options & GET_BITMAP_LOCATION) {
 218                 strcpy(base, "bitmap/location");
 219                 if (load_sys(fname, buf))
 220                         goto abort;
 221                 if (strncmp(buf, "file", 4) == 0)
 222                         sra->bitmap_offset = 1;
 223                 else if (strncmp(buf, "none", 4) == 0)
 224                         sra->bitmap_offset = 0;
 225                 else if (buf[0] == '+')
 226                         sra->bitmap_offset = strtol(buf+1, NULL, 10);
 227                 else
 228                         goto abort;
 229         }
 230
 231         if (! (options & GET_DEVS))
 232                 return sra;
 233
 234         /* Get all the devices as well */
 235         *base = 0;
 236         dir = opendir(fname);
 237         if (!dir)
 238                 goto abort;
 239         sra->array.spare_disks = 0;
 240
 241         while ((de = readdir(dir)) != NULL) {
 242                 char *ep;
 243                 if (de->d_ino == 0 ||
 244                     strncmp(de->d_name, "dev-", 4) != 0)
 245                         continue;
 246                 strcpy(base, de->d_name);
 247                 dbase = base + strlen(base);
 248                 *dbase++ = '/';
 249
 250                 dev = xmalloc(sizeof(*dev));
 251
 252                 /* Always get slot, major, minor */
 253                 strcpy(dbase, "slot");
 254                 if (load_sys(fname, buf)) {
 255                         /* hmm... unable to read 'slot' maybe the device
 256                          * is going away?
 257                          */
 258                         strcpy(dbase, "block");
 259                         if (readlink(fname, buf, sizeof(buf)) < 0 &&
 260                             errno != ENAMETOOLONG) {
 261                                 /* ...yup device is gone */
 262                                 free(dev);
 263                                 continue;
 264                         } else {
 265                                 /* slot is unreadable but 'block' link
 266                                  * still intact... something bad is happening
 267                                  * so abort
 268                                  */
 269                                 free(dev);
 270                                 goto abort;
 271                         }
 272
 273                 }
 274                 strcpy(dev->sys_name, de->d_name);
 275                 dev->disk.raid_disk = strtoul(buf, &ep, 10);
 276                 if (*ep) dev->disk.raid_disk = -1;
 277
 278                 strcpy(dbase, "block/dev");
 279                 if (load_sys(fname, buf)) {
 280                         /* assume this is a stale reference to a hot
 281                          * removed device
 282                          */
 283                         free(dev);
 284                         continue;
 285                 }
 286                 sscanf(buf, "%d:%d", &dev->disk.major, &dev->disk.minor);
 287
 288                 /* special case check for block devices that can go 'offline' */
 289                 strcpy(dbase, "block/device/state");
 290                 if (load_sys(fname, buf) == 0 &&
 291                     strncmp(buf, "offline", 7) == 0) {
 292                         free(dev);
 293                         continue;
 294                 }
 295
 296                 /* finally add this disk to the array */
 297                 dev->next = sra->devs;
 298                 sra->devs = dev;
 299
 300                 if (options & GET_OFFSET) {
 301                         strcpy(dbase, "offset");
 302                         if (load_sys(fname, buf))
 303                                 goto abort;
 304                         dev->data_offset = strtoull(buf, NULL, 0);
 305                 }
 306                 if (options & GET_SIZE) {
 307                         strcpy(dbase, "size");
 308                         if (load_sys(fname, buf))
 309                                 goto abort;
 310                         dev->component_size = strtoull(buf, NULL, 0) * 2;
 311                 }
 312                 if (options & GET_STATE) {
 313                         dev->disk.state = 0;
 314                         strcpy(dbase, "state");
 315                         if (load_sys(fname, buf))
 316                                 goto abort;
 317                         if (strstr(buf, "in_sync"))
 318                                 dev->disk.state |= (1<<MD_DISK_SYNC);
 319                         if (strstr(buf, "faulty"))
 320                                 dev->disk.state |= (1<<MD_DISK_FAULTY);
 321                         if (dev->disk.state == 0)
 322                                 sra->array.spare_disks++;
 323                 }
 324                 if (options & GET_ERROR) {
 325                         strcpy(buf, "errors");
 326                         if (load_sys(fname, buf))
 327                                 goto abort;
 328                         dev->errors = strtoul(buf, NULL, 0);
 329                 }
 330         }
 331         closedir(dir);
 332         return sra;
 333
 334  abort:
 335         if (dir)
 336                 closedir(dir);
 337         sysfs_free(sra);
 338         return NULL;
 339 }
 340
 341 int sysfs_attr_match(const char *attr, const char *str)
 342 {
 343         /* See if attr, read from a sysfs file, matches
 344          * str.  They must either be the same, or attr can
 345          * have a trailing newline or comma
 346          */
 347         while (*attr && *str && *attr == *str) {
 348                 attr++;
 349                 str++;
 350         }
 351
 352         if (*str || (*attr && *attr != ',' && *attr != '\n'))
 353                 return 0;
 354         return 1;
 355 }
 356
 357 int sysfs_match_word(const char *word, char **list)
 358 {
 359         int n;
 360         for (n=0; list[n]; n++)
 361                 if (sysfs_attr_match(word, list[n]))
 362                         break;
 363         return n;
 364 }
 365
 366 unsigned long long get_component_size(int fd)
 367 {
 368         /* Find out the component size of the array.
 369          * We cannot trust GET_ARRAY_INFO ioctl as it's
 370          * size field is only 32bits.
 371          * So look in /sys/block/mdXXX/md/component_size
 372          *
 373          * This returns in units of sectors.
 374          */
 375         struct stat stb;
 376         char fname[50];
 377         int n;
 378         if (fstat(fd, &stb)) return 0;
 379         if (major(stb.st_rdev) != (unsigned)get_mdp_major())
 380                 sprintf(fname, "/sys/block/md%d/md/component_size",
 381                         (int)minor(stb.st_rdev));
 382         else
 383                 sprintf(fname, "/sys/block/md_d%d/md/component_size",
 384                         (int)minor(stb.st_rdev)>>MdpMinorShift);
 385         fd = open(fname, O_RDONLY);
 386         if (fd < 0)
 387                 return 0;
 388         n = read(fd, fname, sizeof(fname));
 389         close(fd);
 390         if (n < 0 || n == sizeof(fname))
 391                 return 0;
 392         fname[n] = 0;
 393         return strtoull(fname, NULL, 10) * 2;
 394 }
 395
 396 int sysfs_set_str(struct mdinfo *sra, struct mdinfo *dev,
 397                   char *name, char *val)
 398 {
 399         char fname[50];
 400         unsigned int n;
 401         int fd;
 402
 403         sprintf(fname, "/sys/block/%s/md/%s/%s",
 404                 sra->sys_name, dev?dev->sys_name:"", name);
 405         fd = open(fname, O_WRONLY);
 406         if (fd < 0)
 407                 return -1;
 408         n = write(fd, val, strlen(val));
 409         close(fd);
 410         if (n != strlen(val)) {
 411                 dprintf(Name ": failed to write '%s' to '%s' (%s)\n",
 412                         val, fname, strerror(errno));
 413                 return -1;
 414         }
 415         return 0;
 416 }
 417
 418 int sysfs_set_num(struct mdinfo *sra, struct mdinfo *dev,
 419                   char *name, unsigned long long val)
 420 {
 421         char valstr[50];
 422         sprintf(valstr, "%llu", val);
 423         return sysfs_set_str(sra, dev, name, valstr);
 424 }
 425
 426 int sysfs_set_num_signed(struct mdinfo *sra, struct mdinfo *dev,
 427                          char *name, long long val)
 428 {
 429         char valstr[50];
 430         sprintf(valstr, "%lli", val);
 431         return sysfs_set_str(sra, dev, name, valstr);
 432 }
 433
 434 int sysfs_uevent(struct mdinfo *sra, char *event)
 435 {
 436         char fname[50];
 437         int n;
 438         int fd;
 439
 440         sprintf(fname, "/sys/block/%s/uevent",
 441                 sra->sys_name);
 442         fd = open(fname, O_WRONLY);
 443         if (fd < 0)
 444                 return -1;
 445         n = write(fd, event, strlen(event));
 446         close(fd);
 447         if (n != (int)strlen(event)) {
 448                 dprintf(Name ": failed to write '%s' to '%s' (%s)\n",
 449                         event, fname, strerror(errno));
 450                 return -1;
 451         }
 452         return 0;
 453 }
 454
 455 int sysfs_attribute_available(struct mdinfo *sra, struct mdinfo *dev, char *name)
 456 {
 457         char fname[50];
 458         struct stat st;
 459
 460         sprintf(fname, "/sys/block/%s/md/%s/%s",
 461                 sra->sys_name, dev?dev->sys_name:"", name);
 462
 463         return stat(fname, &st) == 0;
 464 }
 465
 466 int sysfs_get_fd(struct mdinfo *sra, struct mdinfo *dev,
 467                        char *name)
 468 {
 469         char fname[50];
 470         int fd;
 471
 472         sprintf(fname, "/sys/block/%s/md/%s/%s",
 473                 sra->sys_name, dev?dev->sys_name:"", name);
 474         fd = open(fname, O_RDWR);
 475         if (fd < 0)
 476                 fd = open(fname, O_RDONLY);
 477         return fd;
 478 }
 479
 480 int sysfs_fd_get_ll(int fd, unsigned long long *val)
 481 {
 482         char buf[50];
 483         int n;
 484         char *ep;
 485
 486         lseek(fd, 0, 0);
 487         n = read(fd, buf, sizeof(buf));
 488         if (n <= 0)
 489                 return -2;
 490         buf[n] = 0;
 491         *val = strtoull(buf, &ep, 0);
 492         if (ep == buf || (*ep != 0 && *ep != '\n' && *ep != ' '))
 493                 return -1;
 494         return 0;
 495 }
 496
 497 int sysfs_get_ll(struct mdinfo *sra, struct mdinfo *dev,
 498                        char *name, unsigned long long *val)
 499 {
 500         int n;
 501         int fd;
 502
 503         fd = sysfs_get_fd(sra, dev, name);
 504         if (fd < 0)
 505                 return -1;
 506         n = sysfs_fd_get_ll(fd, val);
 507         close(fd);
 508         return n;
 509 }
 510
 511 int sysfs_fd_get_str(int fd, char *val, int size)
 512 {
 513         int n;
 514
 515         lseek(fd, 0, 0);
 516         n = read(fd, val, size);
 517         if (n <= 0)
 518                 return -1;
 519         val[n] = 0;
 520         return n;
 521 }
 522
 523 int sysfs_get_str(struct mdinfo *sra, struct mdinfo *dev,
 524                        char *name, char *val, int size)
 525 {
 526         int n;
 527         int fd;
 528
 529         fd = sysfs_get_fd(sra, dev, name);
 530         if (fd < 0)
 531                 return -1;
 532         n = sysfs_fd_get_str(fd, val, size);
 533         close(fd);
 534         return n;
 535 }
 536
 537 int sysfs_set_safemode(struct mdinfo *sra, unsigned long ms)
 538 {
 539         unsigned long sec;
 540         unsigned long msec;
 541         char delay[30];
 542
 543         sec = ms / 1000;
 544         msec = ms % 1000;
 545
 546         sprintf(delay, "%ld.%03ld\n", sec, msec);
 547         /*             this '\n' ^ needed for kernels older than 2.6.28 */
 548         return sysfs_set_str(sra, NULL, "safe_mode_delay", delay);
 549 }
 550
 551 int sysfs_set_array(struct mdinfo *info, int vers)
 552 {
 553         int rv = 0;
 554         char ver[100];
 555         int raid_disks = info->array.raid_disks;
 556
 557         ver[0] = 0;
 558         if (info->array.major_version == -1 &&
 559             info->array.minor_version == -2) {
 560                 char buf[1024];
 561
 562                 strcat(strcpy(ver, "external:"), info->text_version);
 563
 564                 /* meta version might already be set if we are setting
 565                  * new geometry for a reshape.  In that case we don't
 566                  * want to over-write the 'readonly' flag that is
 567                  * stored in the metadata version.  So read the current
 568                  * version first, and preserve the flag
 569                  */
 570                 if (sysfs_get_str(info, NULL, "metadata_version",
 571                                   buf, 1024) > 0)
 572                         if (strlen(buf) >= 9 && buf[9] == '-')
 573                                 ver[9] = '-';
 574
 575                 if ((vers % 100) < 2 ||
 576                     sysfs_set_str(info, NULL, "metadata_version",
 577                                   ver) < 0) {
 578                         pr_err("This kernel does not "
 579                                 "support external metadata.\n");
 580                         return 1;
 581                 }
 582         }
 583         if (info->array.level < 0)
 584                 return 0; /* FIXME */
 585         rv |= sysfs_set_str(info, NULL, "level",
 586                             map_num(pers, info->array.level));
 587         if (info->reshape_active && info->delta_disks != UnSet)
 588                 raid_disks -= info->delta_disks;
 589         rv |= sysfs_set_num(info, NULL, "raid_disks", raid_disks);
 590         rv |= sysfs_set_num(info, NULL, "chunk_size", info->array.chunk_size);
 591         rv |= sysfs_set_num(info, NULL, "layout", info->array.layout);
 592         rv |= sysfs_set_num(info, NULL, "component_size", info->component_size/2);
 593         if (info->custom_array_size) {
 594                 int rc;
 595
 596                 rc = sysfs_set_num(info, NULL, "array_size",
 597                                    info->custom_array_size/2);
 598                 if (rc && errno == ENOENT) {
 599                         pr_err("This kernel does not "
 600                                 "have the md/array_size attribute, "
 601                                 "the array may be larger than expected\n");
 602                         rc = 0;
 603                 }
 604                 rv |= rc;
 605         }
 606
 607         if (info->array.level > 0)
 608                 rv |= sysfs_set_num(info, NULL, "resync_start", info->resync_start);
 609
 610         if (info->reshape_active) {
 611                 rv |= sysfs_set_num(info, NULL, "reshape_position",
 612                                     info->reshape_progress);
 613                 rv |= sysfs_set_num(info, NULL, "chunk_size", info->new_chunk);
 614                 rv |= sysfs_set_num(info, NULL, "layout", info->new_layout);
 615                 rv |= sysfs_set_num(info, NULL, "raid_disks",
 616                                     info->array.raid_disks);
 617                 /* We don't set 'new_level' here.  That can only happen
 618                  * once the reshape completes.
 619                  */
 620         }
 621         return rv;
 622 }
 623
 624 int sysfs_add_disk(struct mdinfo *sra, struct mdinfo *sd, int resume)
 625 {
 626         char dv[PATH_MAX];
 627         char nm[PATH_MAX];
 628         char *dname;
 629         int rv;
 630
 631         sprintf(dv, "%d:%d", sd->disk.major, sd->disk.minor);
 632         rv = sysfs_set_str(sra, NULL, "new_dev", dv);
 633         if (rv)
 634                 return rv;
 635
 636         memset(nm, 0, sizeof(nm));
 637         sprintf(dv, "/sys/dev/block/%d:%d", sd->disk.major, sd->disk.minor);
 638         rv = readlink(dv, nm, sizeof(nm)-1);
 639         if (rv <= 0)
 640                 return -1;
 641         nm[rv] = '\0';
 642         dname = strrchr(nm, '/');
 643         if (dname) dname++;
 644         strcpy(sd->sys_name, "dev-");
 645         strcpy(sd->sys_name+4, dname);
 646
 647         /* test write to see if 'recovery_start' is available */
 648         if (resume && sd->recovery_start < MaxSector &&
 649             sysfs_set_num(sra, sd, "recovery_start", 0)) {
 650                 sysfs_set_str(sra, sd, "state", "remove");
 651                 return -1;
 652         }
 653
 654         rv = sysfs_set_num(sra, sd, "offset", sd->data_offset);
 655         rv |= sysfs_set_num(sra, sd, "size", (sd->component_size+1) / 2);
 656         if (sra->array.level != LEVEL_CONTAINER) {
 657                 if (sd->recovery_start == MaxSector)
 658                         /* This can correctly fail if array isn't started,
 659                          * yet, so just ignore status for now.
 660                          */
 661                         sysfs_set_str(sra, sd, "state", "insync");
 662                 if (sd->disk.raid_disk >= 0)
 663                         rv |= sysfs_set_num(sra, sd, "slot", sd->disk.raid_disk);
 664                 if (resume)
 665                         sysfs_set_num(sra, sd, "recovery_start", sd->recovery_start);
 666         }
 667         return rv;
 668 }
 669
 670 #if 0
 671 int sysfs_disk_to_sg(int fd)
 672 {
 673         /* from an open block device, try find and open its corresponding
 674          * scsi_generic interface
 675          */
 676         struct stat st;
 677         char path[256];
 678         char sg_path[256];
 679         char sg_major_minor[8];
 680         char *c;
 681         DIR *dir;
 682         struct dirent *de;
 683         int major, minor, rv;
 684
 685         if (fstat(fd, &st))
 686                 return -1;
 687
 688         snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/device",
 689                  major(st.st_rdev), minor(st.st_rdev));
 690
 691         dir = opendir(path);
 692         if (!dir)
 693                 return -1;
 694
 695         de = readdir(dir);
 696         while (de) {
 697                 if (strncmp("scsi_generic:", de->d_name,
 698                             strlen("scsi_generic:")) == 0)
 699                         break;
 700                 de = readdir(dir);
 701         }
 702         closedir(dir);
 703
 704         if (!de)
 705                 return -1;
 706
 707         snprintf(sg_path, sizeof(sg_path), "%s/%s/dev", path, de->d_name);
 708         fd = open(sg_path, O_RDONLY);
 709         if (fd < 0)
 710                 return fd;
 711
 712         rv = read(fd, sg_major_minor, sizeof(sg_major_minor));
 713         close(fd);
 714         if (rv < 0)
 715                 return -1;
 716         else
 717                 sg_major_minor[rv - 1] = '\0';
 718
 719         c = strchr(sg_major_minor, ':');
 720         *c = '\0';
 721         c++;
 722         major = strtol(sg_major_minor, NULL, 10);
 723         minor = strtol(c, NULL, 10);
 724         snprintf(path, sizeof(path), "/dev/.tmp.md.%d:%d:%d",
 725                  (int) getpid(), major, minor);
 726         if (mknod(path, S_IFCHR|0600, makedev(major, minor))==0) {
 727                         fd = open(path, O_RDONLY);
 728                         unlink(path);
 729                         return fd;
 730         }
 731
 732         return -1;
 733 }
 734 #endif
 735
 736 int sysfs_disk_to_scsi_id(int fd, __u32 *id)
 737 {
 738         /* from an open block device, try to retrieve it scsi_id */
 739         struct stat st;
 740         char path[256];
 741         DIR *dir;
 742         struct dirent *de;
 743         int host, bus, target, lun;
 744
 745         if (fstat(fd, &st))
 746                 return 1;
 747
 748         snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/device/scsi_device",
 749                  major(st.st_rdev), minor(st.st_rdev));
 750
 751         dir = opendir(path);
 752         if (!dir)
 753                 return 1;
 754
 755         for (de = readdir(dir); de; de = readdir(dir)) {
 756                 int count;
 757
 758                 if (de->d_type != DT_DIR)
 759                         continue;
 760
 761                 count = sscanf(de->d_name, "%d:%d:%d:%d", &host, &bus, &target, &lun);
 762                 if (count == 4)
 763                         break;
 764         }
 765         closedir(dir);
 766
 767         if (!de)
 768                 return 1;
 769
 770         *id = (host << 24) | (bus << 16) | (target << 8) | (lun << 0);
 771         return 0;
 772 }
 773
 774
 775 int sysfs_unique_holder(int devnum, long rdev)
 776 {
 777         /* Check that devnum is a holder of rdev,
 778          * and is the only holder.
 779          * we should be locked against races by
 780          * an O_EXCL on devnum
 781          * Return values:
 782          *  0 - not unique, not even a holder
 783          *  1 - unique, this is the only holder.
 784          *  2/3 - not unique, there is another holder
 785          * -1 - error, cannot find the holders
 786          */
 787         DIR *dir;
 788         struct dirent *de;
 789         char dirname[100];
 790         char l;
 791         int ret = 0;
 792         sprintf(dirname, "/sys/dev/block/%d:%d/holders",
 793                 major(rdev), minor(rdev));
 794         dir = opendir(dirname);
 795         if (!dir)
 796                 return -1;
 797         l = strlen(dirname);
 798         while ((de = readdir(dir)) != NULL) {
 799                 char buf[10];
 800                 int n;
 801                 int mj, mn;
 802                 char c;
 803                 int fd;
 804
 805                 if (de->d_ino == 0)
 806                         continue;
 807                 if (de->d_name[0] == '.')
 808                         continue;
 809                 strcpy(dirname+l, "/");
 810                 strcat(dirname+l, de->d_name);
 811                 strcat(dirname+l, "/dev");
 812                 fd = open(dirname, O_RDONLY);
 813                 if (fd < 0) {
 814                         /* Probably a race, just ignore this */
 815                         continue;
 816                 }
 817                 n = read(fd, buf, sizeof(buf)-1);
 818                 close(fd);
 819                 if (n < 0)
 820                         continue;
 821                 buf[n] = 0;
 822                 if (sscanf(buf, "%d:%d%c", &mj, &mn, &c) != 3 ||
 823                     c != '\n')
 824                         continue;
 825                 if (mj != MD_MAJOR)
 826                         mn = -1-(mn>>6);
 827
 828                 if (devnum == mn)
 829                         ret |= 1;
 830                 else
 831                         ret |= 2;
 832         }
 833         closedir(dir);
 834         return ret;
 835 }
 836
 837 int sysfs_freeze_array(struct mdinfo *sra)
 838 {
 839         /* Try to freeze resync/rebuild on this array/container.
 840          * Return -1 if the array is busy,
 841          * return 0 if this kernel doesn't support 'frozen'
 842          * return 1 if it worked.
 843          */
 844         char buf[20];
 845
 846         if (!sysfs_attribute_available(sra, NULL, "sync_action"))
 847                 return 1; /* no sync_action == frozen */
 848         if (sysfs_get_str(sra, NULL, "sync_action", buf, 20) <= 0)
 849                 return 0;
 850         if (strcmp(buf, "frozen\n") == 0)
 851                 /* Already frozen */
 852                 return 0;
 853         if (strcmp(buf, "idle\n") != 0)
 854                 return -1;
 855         if (sysfs_set_str(sra, NULL, "sync_action", "frozen") < 0)
 856                 return 0;
 857         return 1;
 858 }