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 = malloc(sizeof(*sra));
 109         if (sra == NULL)
 110                 return sra;
 111         memset(sra, 0, sizeof(*sra));
 112         sysfs_init(sra, fd, devnum);
 113         if (sra->sys_name[0] == 0) {
 114                 free(sra);
 115                 return NULL;
 116         }
 117
 118         sprintf(fname, "/sys/block/%s/md/", sra->sys_name);
 119         base = fname + strlen(fname);
 120
 121         sra->devs = NULL;
 122         if (options & GET_VERSION) {
 123                 strcpy(base, "metadata_version");
 124                 if (load_sys(fname, buf))
 125                         goto abort;
 126                 if (strncmp(buf, "none", 4) == 0) {
 127                         sra->array.major_version =
 128                                 sra->array.minor_version = -1;
 129                         strcpy(sra->text_version, "");
 130                 } else if (strncmp(buf, "external:", 9) == 0) {
 131                         sra->array.major_version = -1;
 132                         sra->array.minor_version = -2;
 133                         strcpy(sra->text_version, buf+9);
 134                 } else {
 135                         sscanf(buf, "%d.%d",
 136                                &sra->array.major_version,
 137                                &sra->array.minor_version);
 138                         strcpy(sra->text_version, buf);
 139                 }
 140         }
 141         if (options & GET_LEVEL) {
 142                 strcpy(base, "level");
 143                 if (load_sys(fname, buf))
 144                         goto abort;
 145                 sra->array.level = map_name(pers, buf);
 146         }
 147         if (options & GET_LAYOUT) {
 148                 strcpy(base, "layout");
 149                 if (load_sys(fname, buf))
 150                         goto abort;
 151                 sra->array.layout = strtoul(buf, NULL, 0);
 152         }
 153         if (options & GET_DISKS) {
 154                 strcpy(base, "raid_disks");
 155                 if (load_sys(fname, buf))
 156                         goto abort;
 157                 sra->array.raid_disks = strtoul(buf, NULL, 0);
 158         }
 159         if (options & GET_DEGRADED) {
 160                 strcpy(base, "degraded");
 161                 if (load_sys(fname, buf))
 162                         goto abort;
 163                 sra->array.failed_disks = strtoul(buf, NULL, 0);
 164         }
 165         if (options & GET_COMPONENT) {
 166                 strcpy(base, "component_size");
 167                 if (load_sys(fname, buf))
 168                         goto abort;
 169                 sra->component_size = strtoull(buf, NULL, 0);
 170                 /* sysfs reports "K", but we want sectors */
 171                 sra->component_size *= 2;
 172         }
 173         if (options & GET_CHUNK) {
 174                 strcpy(base, "chunk_size");
 175                 if (load_sys(fname, buf))
 176                         goto abort;
 177                 sra->array.chunk_size = strtoul(buf, NULL, 0);
 178         }
 179         if (options & GET_CACHE) {
 180                 strcpy(base, "stripe_cache_size");
 181                 if (load_sys(fname, buf))
 182                         goto abort;
 183                 sra->cache_size = strtoul(buf, NULL, 0);
 184         }
 185         if (options & GET_MISMATCH) {
 186                 strcpy(base, "mismatch_cnt");
 187                 if (load_sys(fname, buf))
 188                         goto abort;
 189                 sra->mismatch_cnt = strtoul(buf, NULL, 0);
 190         }
 191         if (options & GET_SAFEMODE) {
 192                 int scale = 1;
 193                 int dot = 0;
 194                 unsigned i;
 195                 unsigned long msec;
 196                 size_t len;
 197
 198                 strcpy(base, "safe_mode_delay");
 199                 if (load_sys(fname, buf))
 200                         goto abort;
 201
 202                 /* remove a period, and count digits after it */
 203                 len = strlen(buf);
 204                 for (i = 0; i < len; i++) {
 205                         if (dot) {
 206                                 if (isdigit(buf[i])) {
 207                                         buf[i-1] = buf[i];
 208                                         scale *= 10;
 209                                 }
 210                                 buf[i] = 0;
 211                         } else if (buf[i] == '.') {
 212                                 dot=1;
 213                                 buf[i] = 0;
 214                         }
 215                 }
 216                 msec = strtoul(buf, NULL, 10);
 217                 msec = (msec * 1000) / scale;
 218                 sra->safe_mode_delay = msec;
 219         }
 220         if (options & GET_BITMAP_LOCATION) {
 221                 strcpy(base, "bitmap/location");
 222                 if (load_sys(fname, buf))
 223                         goto abort;
 224                 if (strncmp(buf, "file", 4) == 0)
 225                         sra->bitmap_offset = 1;
 226                 else if (strncmp(buf, "none", 4) == 0)
 227                         sra->bitmap_offset = 0;
 228                 else if (buf[0] == '+')
 229                         sra->bitmap_offset = strtol(buf+1, NULL, 10);
 230                 else
 231                         goto abort;
 232         }
 233
 234         if (! (options & GET_DEVS))
 235                 return sra;
 236
 237         /* Get all the devices as well */
 238         *base = 0;
 239         dir = opendir(fname);
 240         if (!dir)
 241                 goto abort;
 242         sra->array.spare_disks = 0;
 243
 244         while ((de = readdir(dir)) != NULL) {
 245                 char *ep;
 246                 if (de->d_ino == 0 ||
 247                     strncmp(de->d_name, "dev-", 4) != 0)
 248                         continue;
 249                 strcpy(base, de->d_name);
 250                 dbase = base + strlen(base);
 251                 *dbase++ = '/';
 252
 253                 dev = malloc(sizeof(*dev));
 254                 if (!dev)
 255                         goto abort;
 256
 257                 /* Always get slot, major, minor */
 258                 strcpy(dbase, "slot");
 259                 if (load_sys(fname, buf)) {
 260                         /* hmm... unable to read 'slot' maybe the device
 261                          * is going away?
 262                          */
 263                         strcpy(dbase, "block");
 264                         if (readlink(fname, buf, sizeof(buf)) < 0 &&
 265                             errno != ENAMETOOLONG) {
 266                                 /* ...yup device is gone */
 267                                 free(dev);
 268                                 continue;
 269                         } else {
 270                                 /* slot is unreadable but 'block' link
 271                                  * still intact... something bad is happening
 272                                  * so abort
 273                                  */
 274                                 free(dev);
 275                                 goto abort;
 276                         }
 277
 278                 }
 279                 strcpy(dev->sys_name, de->d_name);
 280                 dev->disk.raid_disk = strtoul(buf, &ep, 10);
 281                 if (*ep) dev->disk.raid_disk = -1;
 282
 283                 strcpy(dbase, "block/dev");
 284                 if (load_sys(fname, buf)) {
 285                         /* assume this is a stale reference to a hot
 286                          * removed device
 287                          */
 288                         free(dev);
 289                         continue;
 290                 }
 291                 sscanf(buf, "%d:%d", &dev->disk.major, &dev->disk.minor);
 292
 293                 /* special case check for block devices that can go 'offline' */
 294                 strcpy(dbase, "block/device/state");
 295                 if (load_sys(fname, buf) == 0 &&
 296                     strncmp(buf, "offline", 7) == 0) {
 297                         free(dev);
 298                         continue;
 299                 }
 300
 301                 /* finally add this disk to the array */
 302                 dev->next = sra->devs;
 303                 sra->devs = dev;
 304
 305                 if (options & GET_OFFSET) {
 306                         strcpy(dbase, "offset");
 307                         if (load_sys(fname, buf))
 308                                 goto abort;
 309                         dev->data_offset = strtoull(buf, NULL, 0);
 310                 }
 311                 if (options & GET_SIZE) {
 312                         strcpy(dbase, "size");
 313                         if (load_sys(fname, buf))
 314                                 goto abort;
 315                         dev->component_size = strtoull(buf, NULL, 0) * 2;
 316                 }
 317                 if (options & GET_STATE) {
 318                         dev->disk.state = 0;
 319                         strcpy(dbase, "state");
 320                         if (load_sys(fname, buf))
 321                                 goto abort;
 322                         if (strstr(buf, "in_sync"))
 323                                 dev->disk.state |= (1<<MD_DISK_SYNC);
 324                         if (strstr(buf, "faulty"))
 325                                 dev->disk.state |= (1<<MD_DISK_FAULTY);
 326                         if (dev->disk.state == 0)
 327                                 sra->array.spare_disks++;
 328                 }
 329                 if (options & GET_ERROR) {
 330                         strcpy(buf, "errors");
 331                         if (load_sys(fname, buf))
 332                                 goto abort;
 333                         dev->errors = strtoul(buf, NULL, 0);
 334                 }
 335         }
 336         closedir(dir);
 337         return sra;
 338
 339  abort:
 340         if (dir)
 341                 closedir(dir);
 342         sysfs_free(sra);
 343         return NULL;
 344 }
 345
 346 int sysfs_attr_match(const char *attr, const char *str)
 347 {
 348         /* See if attr, read from a sysfs file, matches
 349          * str.  They must either be the same, or attr can
 350          * have a trailing newline or comma
 351          */
 352         while (*attr && *str && *attr == *str) {
 353                 attr++;
 354                 str++;
 355         }
 356
 357         if (*str || (*attr && *attr != ',' && *attr != '\n'))
 358                 return 0;
 359         return 1;
 360 }
 361
 362 int sysfs_match_word(const char *word, char **list)
 363 {
 364         int n;
 365         for (n=0; list[n]; n++)
 366                 if (sysfs_attr_match(word, list[n]))
 367                         break;
 368         return n;
 369 }
 370
 371 unsigned long long get_component_size(int fd)
 372 {
 373         /* Find out the component size of the array.
 374          * We cannot trust GET_ARRAY_INFO ioctl as it's
 375          * size field is only 32bits.
 376          * So look in /sys/block/mdXXX/md/component_size
 377          *
 378          * This returns in units of sectors.
 379          */
 380         struct stat stb;
 381         char fname[50];
 382         int n;
 383         if (fstat(fd, &stb)) return 0;
 384         if (major(stb.st_rdev) != (unsigned)get_mdp_major())
 385                 sprintf(fname, "/sys/block/md%d/md/component_size",
 386                         (int)minor(stb.st_rdev));
 387         else
 388                 sprintf(fname, "/sys/block/md_d%d/md/component_size",
 389                         (int)minor(stb.st_rdev)>>MdpMinorShift);
 390         fd = open(fname, O_RDONLY);
 391         if (fd < 0)
 392                 return 0;
 393         n = read(fd, fname, sizeof(fname));
 394         close(fd);
 395         if (n < 0 || n == sizeof(fname))
 396                 return 0;
 397         fname[n] = 0;
 398         return strtoull(fname, NULL, 10) * 2;
 399 }
 400
 401 int sysfs_set_str(struct mdinfo *sra, struct mdinfo *dev,
 402                   char *name, char *val)
 403 {
 404         char fname[50];
 405         unsigned int n;
 406         int fd;
 407
 408         sprintf(fname, "/sys/block/%s/md/%s/%s",
 409                 sra->sys_name, dev?dev->sys_name:"", name);
 410         fd = open(fname, O_WRONLY);
 411         if (fd < 0)
 412                 return -1;
 413         n = write(fd, val, strlen(val));
 414         close(fd);
 415         if (n != strlen(val)) {
 416                 dprintf(Name ": failed to write '%s' to '%s' (%s)\n",
 417                         val, fname, strerror(errno));
 418                 return -1;
 419         }
 420         return 0;
 421 }
 422
 423 int sysfs_set_num(struct mdinfo *sra, struct mdinfo *dev,
 424                   char *name, unsigned long long val)
 425 {
 426         char valstr[50];
 427         sprintf(valstr, "%llu", val);
 428         return sysfs_set_str(sra, dev, name, valstr);
 429 }
 430
 431 int sysfs_set_num_signed(struct mdinfo *sra, struct mdinfo *dev,
 432                          char *name, long long val)
 433 {
 434         char valstr[50];
 435         sprintf(valstr, "%lli", val);
 436         return sysfs_set_str(sra, dev, name, valstr);
 437 }
 438
 439 int sysfs_uevent(struct mdinfo *sra, char *event)
 440 {
 441         char fname[50];
 442         int n;
 443         int fd;
 444
 445         sprintf(fname, "/sys/block/%s/uevent",
 446                 sra->sys_name);
 447         fd = open(fname, O_WRONLY);
 448         if (fd < 0)
 449                 return -1;
 450         n = write(fd, event, strlen(event));
 451         close(fd);
 452         if (n != (int)strlen(event)) {
 453                 dprintf(Name ": failed to write '%s' to '%s' (%s)\n",
 454                         event, fname, strerror(errno));
 455                 return -1;
 456         }
 457         return 0;
 458 }
 459
 460 int sysfs_attribute_available(struct mdinfo *sra, struct mdinfo *dev, char *name)
 461 {
 462         char fname[50];
 463         struct stat st;
 464
 465         sprintf(fname, "/sys/block/%s/md/%s/%s",
 466                 sra->sys_name, dev?dev->sys_name:"", name);
 467
 468         return stat(fname, &st) == 0;
 469 }
 470
 471 int sysfs_get_fd(struct mdinfo *sra, struct mdinfo *dev,
 472                        char *name)
 473 {
 474         char fname[50];
 475         int fd;
 476
 477         sprintf(fname, "/sys/block/%s/md/%s/%s",
 478                 sra->sys_name, dev?dev->sys_name:"", name);
 479         fd = open(fname, O_RDWR);
 480         if (fd < 0)
 481                 fd = open(fname, O_RDONLY);
 482         return fd;
 483 }
 484
 485 int sysfs_fd_get_ll(int fd, unsigned long long *val)
 486 {
 487         char buf[50];
 488         int n;
 489         char *ep;
 490
 491         lseek(fd, 0, 0);
 492         n = read(fd, buf, sizeof(buf));
 493         if (n <= 0)
 494                 return -2;
 495         buf[n] = 0;
 496         *val = strtoull(buf, &ep, 0);
 497         if (ep == buf || (*ep != 0 && *ep != '\n' && *ep != ' '))
 498                 return -1;
 499         return 0;
 500 }
 501
 502 int sysfs_get_ll(struct mdinfo *sra, struct mdinfo *dev,
 503                        char *name, unsigned long long *val)
 504 {
 505         int n;
 506         int fd;
 507
 508         fd = sysfs_get_fd(sra, dev, name);
 509         if (fd < 0)
 510                 return -1;
 511         n = sysfs_fd_get_ll(fd, val);
 512         close(fd);
 513         return n;
 514 }
 515
 516 int sysfs_fd_get_str(int fd, char *val, int size)
 517 {
 518         int n;
 519
 520         lseek(fd, 0, 0);
 521         n = read(fd, val, size);
 522         if (n <= 0)
 523                 return -1;
 524         val[n] = 0;
 525         return n;
 526 }
 527
 528 int sysfs_get_str(struct mdinfo *sra, struct mdinfo *dev,
 529                        char *name, char *val, int size)
 530 {
 531         int n;
 532         int fd;
 533
 534         fd = sysfs_get_fd(sra, dev, name);
 535         if (fd < 0)
 536                 return -1;
 537         n = sysfs_fd_get_str(fd, val, size);
 538         close(fd);
 539         return n;
 540 }
 541
 542 int sysfs_set_safemode(struct mdinfo *sra, unsigned long ms)
 543 {
 544         unsigned long sec;
 545         unsigned long msec;
 546         char delay[30];
 547
 548         sec = ms / 1000;
 549         msec = ms % 1000;
 550
 551         sprintf(delay, "%ld.%03ld\n", sec, msec);
 552         /*             this '\n' ^ needed for kernels older than 2.6.28 */
 553         return sysfs_set_str(sra, NULL, "safe_mode_delay", delay);
 554 }
 555
 556 int sysfs_set_array(struct mdinfo *info, int vers)
 557 {
 558         int rv = 0;
 559         char ver[100];
 560         int raid_disks = info->array.raid_disks;
 561
 562         ver[0] = 0;
 563         if (info->array.major_version == -1 &&
 564             info->array.minor_version == -2) {
 565                 char buf[1024];
 566
 567                 strcat(strcpy(ver, "external:"), info->text_version);
 568
 569                 /* meta version might already be set if we are setting
 570                  * new geometry for a reshape.  In that case we don't
 571                  * want to over-write the 'readonly' flag that is
 572                  * stored in the metadata version.  So read the current
 573                  * version first, and preserve the flag
 574                  */
 575                 if (sysfs_get_str(info, NULL, "metadata_version",
 576                                   buf, 1024) > 0)
 577                         if (strlen(buf) >= 9 && buf[9] == '-')
 578                                 ver[9] = '-';
 579
 580                 if ((vers % 100) < 2 ||
 581                     sysfs_set_str(info, NULL, "metadata_version",
 582                                   ver) < 0) {
 583                         fprintf(stderr, Name ": This kernel does not "
 584                                 "support external metadata.\n");
 585                         return 1;
 586                 }
 587         }
 588         if (info->array.level < 0)
 589                 return 0; /* FIXME */
 590         rv |= sysfs_set_str(info, NULL, "level",
 591                             map_num(pers, info->array.level));
 592         if (info->reshape_active && info->delta_disks != UnSet)
 593                 raid_disks -= info->delta_disks;
 594         rv |= sysfs_set_num(info, NULL, "raid_disks", raid_disks);
 595         rv |= sysfs_set_num(info, NULL, "chunk_size", info->array.chunk_size);
 596         rv |= sysfs_set_num(info, NULL, "layout", info->array.layout);
 597         rv |= sysfs_set_num(info, NULL, "component_size", info->component_size/2);
 598         if (info->custom_array_size) {
 599                 int rc;
 600
 601                 rc = sysfs_set_num(info, NULL, "array_size",
 602                                    info->custom_array_size/2);
 603                 if (rc && errno == ENOENT) {
 604                         fprintf(stderr, Name ": This kernel does not "
 605                                 "have the md/array_size attribute, "
 606                                 "the array may be larger than expected\n");
 607                         rc = 0;
 608                 }
 609                 rv |= rc;
 610         }
 611
 612         if (info->array.level > 0)
 613                 rv |= sysfs_set_num(info, NULL, "resync_start", info->resync_start);
 614
 615         if (info->reshape_active) {
 616                 rv |= sysfs_set_num(info, NULL, "reshape_position",
 617                                     info->reshape_progress);
 618                 rv |= sysfs_set_num(info, NULL, "chunk_size", info->new_chunk);
 619                 rv |= sysfs_set_num(info, NULL, "layout", info->new_layout);
 620                 rv |= sysfs_set_num(info, NULL, "raid_disks",
 621                                     info->array.raid_disks);
 622                 /* We don't set 'new_level' here.  That can only happen
 623                  * once the reshape completes.
 624                  */
 625         }
 626         return rv;
 627 }
 628
 629 int sysfs_add_disk(struct mdinfo *sra, struct mdinfo *sd, int resume)
 630 {
 631         char dv[PATH_MAX];
 632         char nm[PATH_MAX];
 633         char *dname;
 634         int rv;
 635
 636         sprintf(dv, "%d:%d", sd->disk.major, sd->disk.minor);
 637         rv = sysfs_set_str(sra, NULL, "new_dev", dv);
 638         if (rv)
 639                 return rv;
 640
 641         memset(nm, 0, sizeof(nm));
 642         sprintf(dv, "/sys/dev/block/%d:%d", sd->disk.major, sd->disk.minor);
 643         rv = readlink(dv, nm, sizeof(nm)-1);
 644         if (rv <= 0)
 645                 return -1;
 646         nm[rv] = '\0';
 647         dname = strrchr(nm, '/');
 648         if (dname) dname++;
 649         strcpy(sd->sys_name, "dev-");
 650         strcpy(sd->sys_name+4, dname);
 651
 652         /* test write to see if 'recovery_start' is available */
 653         if (resume && sd->recovery_start < MaxSector &&
 654             sysfs_set_num(sra, sd, "recovery_start", 0)) {
 655                 sysfs_set_str(sra, sd, "state", "remove");
 656                 return -1;
 657         }
 658
 659         rv = sysfs_set_num(sra, sd, "offset", sd->data_offset);
 660         rv |= sysfs_set_num(sra, sd, "size", (sd->component_size+1) / 2);
 661         if (sra->array.level != LEVEL_CONTAINER) {
 662                 if (sd->recovery_start == MaxSector)
 663                         /* This can correctly fail if array isn't started,
 664                          * yet, so just ignore status for now.
 665                          */
 666                         sysfs_set_str(sra, sd, "state", "insync");
 667                 if (sd->disk.raid_disk >= 0)
 668                         rv |= sysfs_set_num(sra, sd, "slot", sd->disk.raid_disk);
 669                 if (resume)
 670                         sysfs_set_num(sra, sd, "recovery_start", sd->recovery_start);
 671         }
 672         return rv;
 673 }
 674
 675 #if 0
 676 int sysfs_disk_to_sg(int fd)
 677 {
 678         /* from an open block device, try find and open its corresponding
 679          * scsi_generic interface
 680          */
 681         struct stat st;
 682         char path[256];
 683         char sg_path[256];
 684         char sg_major_minor[8];
 685         char *c;
 686         DIR *dir;
 687         struct dirent *de;
 688         int major, minor, rv;
 689
 690         if (fstat(fd, &st))
 691                 return -1;
 692
 693         snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/device",
 694                  major(st.st_rdev), minor(st.st_rdev));
 695
 696         dir = opendir(path);
 697         if (!dir)
 698                 return -1;
 699
 700         de = readdir(dir);
 701         while (de) {
 702                 if (strncmp("scsi_generic:", de->d_name,
 703                             strlen("scsi_generic:")) == 0)
 704                         break;
 705                 de = readdir(dir);
 706         }
 707         closedir(dir);
 708
 709         if (!de)
 710                 return -1;
 711
 712         snprintf(sg_path, sizeof(sg_path), "%s/%s/dev", path, de->d_name);
 713         fd = open(sg_path, O_RDONLY);
 714         if (fd < 0)
 715                 return fd;
 716
 717         rv = read(fd, sg_major_minor, sizeof(sg_major_minor));
 718         close(fd);
 719         if (rv < 0)
 720                 return -1;
 721         else
 722                 sg_major_minor[rv - 1] = '\0';
 723
 724         c = strchr(sg_major_minor, ':');
 725         *c = '\0';
 726         c++;
 727         major = strtol(sg_major_minor, NULL, 10);
 728         minor = strtol(c, NULL, 10);
 729         snprintf(path, sizeof(path), "/dev/.tmp.md.%d:%d:%d",
 730                  (int) getpid(), major, minor);
 731         if (mknod(path, S_IFCHR|0600, makedev(major, minor))==0) {
 732                         fd = open(path, O_RDONLY);
 733                         unlink(path);
 734                         return fd;
 735         }
 736
 737         return -1;
 738 }
 739 #endif
 740
 741 int sysfs_disk_to_scsi_id(int fd, __u32 *id)
 742 {
 743         /* from an open block device, try to retrieve it scsi_id */
 744         struct stat st;
 745         char path[256];
 746         DIR *dir;
 747         struct dirent *de;
 748         int host, bus, target, lun;
 749
 750         if (fstat(fd, &st))
 751                 return 1;
 752
 753         snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/device/scsi_device",
 754                  major(st.st_rdev), minor(st.st_rdev));
 755
 756         dir = opendir(path);
 757         if (!dir)
 758                 return 1;
 759
 760         for (de = readdir(dir); de; de = readdir(dir)) {
 761                 int count;
 762
 763                 if (de->d_type != DT_DIR)
 764                         continue;
 765
 766                 count = sscanf(de->d_name, "%d:%d:%d:%d", &host, &bus, &target, &lun);
 767                 if (count == 4)
 768                         break;
 769         }
 770         closedir(dir);
 771
 772         if (!de)
 773                 return 1;
 774
 775         *id = (host << 24) | (bus << 16) | (target << 8) | (lun << 0);
 776         return 0;
 777 }
 778
 779
 780 int sysfs_unique_holder(int devnum, long rdev)
 781 {
 782         /* Check that devnum is a holder of rdev,
 783          * and is the only holder.
 784          * we should be locked against races by
 785          * an O_EXCL on devnum
 786          */
 787         DIR *dir;
 788         struct dirent *de;
 789         char dirname[100];
 790         char l;
 791         int found = 0;
 792         sprintf(dirname, "/sys/dev/block/%d:%d/holders",
 793                 major(rdev), minor(rdev));
 794         dir = opendir(dirname);
 795         errno = ENOENT;
 796         if (!dir)
 797                 return 0;
 798         l = strlen(dirname);
 799         while ((de = readdir(dir)) != NULL) {
 800                 char buf[10];
 801                 int n;
 802                 int mj, mn;
 803                 char c;
 804                 int fd;
 805
 806                 if (de->d_ino == 0)
 807                         continue;
 808                 if (de->d_name[0] == '.')
 809                         continue;
 810                 strcpy(dirname+l, "/");
 811                 strcat(dirname+l, de->d_name);
 812                 strcat(dirname+l, "/dev");
 813                 fd = open(dirname, O_RDONLY);
 814                 if (fd < 0) {
 815                         errno = ENOENT;
 816                         break;
 817                 }
 818                 n = read(fd, buf, sizeof(buf)-1);
 819                 close(fd);
 820                 if (n < 0)
 821                         continue;
 822                 buf[n] = 0;
 823                 if (sscanf(buf, "%d:%d%c", &mj, &mn, &c) != 3 ||
 824                     c != '\n') {
 825                         errno = ENOENT;
 826                         break;
 827                 }
 828                 if (mj != MD_MAJOR)
 829                         mn = -1-(mn>>6);
 830
 831                 if (devnum != mn) {
 832                         errno = EEXIST;
 833                         break;
 834                 }
 835                 found = 1;
 836         }
 837         closedir(dir);
 838         if (de)
 839                 return 0;
 840         else
 841                 return found;
 842 }
 843
 844 int sysfs_freeze_array(struct mdinfo *sra)
 845 {
 846         /* Try to freeze resync/rebuild on this array/container.
 847          * Return -1 if the array is busy,
 848          * return 0 if this kernel doesn't support 'frozen'
 849          * return 1 if it worked.
 850          */
 851         char buf[20];
 852
 853         if (!sysfs_attribute_available(sra, NULL, "sync_action"))
 854                 return 1; /* no sync_action == frozen */
 855         if (sysfs_get_str(sra, NULL, "sync_action", buf, 20) <= 0)
 856                 return 0;
 857         if (strcmp(buf, "frozen\n") == 0)
 858                 /* Already frozen */
 859                 return 0;
 860         if (strcmp(buf, "idle\n") != 0)
 861                 return -1;
 862         if (sysfs_set_str(sra, NULL, "sync_action", "frozen") < 0)
 863                 return 0;
 864         return 1;
 865 }