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
 221         if (! (options & GET_DEVS))
 222                 return sra;
 223
 224         /* Get all the devices as well */
 225         *base = 0;
 226         dir = opendir(fname);
 227         if (!dir)
 228                 goto abort;
 229         sra->array.spare_disks = 0;
 230
 231         while ((de = readdir(dir)) != NULL) {
 232                 char *ep;
 233                 if (de->d_ino == 0 ||
 234                     strncmp(de->d_name, "dev-", 4) != 0)
 235                         continue;
 236                 strcpy(base, de->d_name);
 237                 dbase = base + strlen(base);
 238                 *dbase++ = '/';
 239
 240                 dev = malloc(sizeof(*dev));
 241                 if (!dev)
 242                         goto abort;
 243
 244                 /* Always get slot, major, minor */
 245                 strcpy(dbase, "slot");
 246                 if (load_sys(fname, buf)) {
 247                         /* hmm... unable to read 'slot' maybe the device
 248                          * is going away?
 249                          */
 250                         strcpy(dbase, "block");
 251                         if (readlink(fname, buf, sizeof(buf)) < 0 &&
 252                             errno != ENAMETOOLONG) {
 253                                 /* ...yup device is gone */
 254                                 free(dev);
 255                                 continue;
 256                         } else {
 257                                 /* slot is unreadable but 'block' link
 258                                  * still intact... something bad is happening
 259                                  * so abort
 260                                  */
 261                                 free(dev);
 262                                 goto abort;
 263                         }
 264
 265                 }
 266                 strcpy(dev->sys_name, de->d_name);
 267                 dev->disk.raid_disk = strtoul(buf, &ep, 10);
 268                 if (*ep) dev->disk.raid_disk = -1;
 269
 270                 strcpy(dbase, "block/dev");
 271                 if (load_sys(fname, buf)) {
 272                         /* assume this is a stale reference to a hot
 273                          * removed device
 274                          */
 275                         free(dev);
 276                         continue;
 277                 }
 278                 sscanf(buf, "%d:%d", &dev->disk.major, &dev->disk.minor);
 279
 280                 /* special case check for block devices that can go 'offline' */
 281                 strcpy(dbase, "block/device/state");
 282                 if (load_sys(fname, buf) == 0 &&
 283                     strncmp(buf, "offline", 7) == 0) {
 284                         free(dev);
 285                         continue;
 286                 }
 287
 288                 /* finally add this disk to the array */
 289                 dev->next = sra->devs;
 290                 sra->devs = dev;
 291
 292                 if (options & GET_OFFSET) {
 293                         strcpy(dbase, "offset");
 294                         if (load_sys(fname, buf))
 295                                 goto abort;
 296                         dev->data_offset = strtoull(buf, NULL, 0);
 297                 }
 298                 if (options & GET_SIZE) {
 299                         strcpy(dbase, "size");
 300                         if (load_sys(fname, buf))
 301                                 goto abort;
 302                         dev->component_size = strtoull(buf, NULL, 0) * 2;
 303                 }
 304                 if (options & GET_STATE) {
 305                         dev->disk.state = 0;
 306                         strcpy(dbase, "state");
 307                         if (load_sys(fname, buf))
 308                                 goto abort;
 309                         if (strstr(buf, "in_sync"))
 310                                 dev->disk.state |= (1<<MD_DISK_SYNC);
 311                         if (strstr(buf, "faulty"))
 312                                 dev->disk.state |= (1<<MD_DISK_FAULTY);
 313                         if (dev->disk.state == 0)
 314                                 sra->array.spare_disks++;
 315                 }
 316                 if (options & GET_ERROR) {
 317                         strcpy(buf, "errors");
 318                         if (load_sys(fname, buf))
 319                                 goto abort;
 320                         dev->errors = strtoul(buf, NULL, 0);
 321                 }
 322         }
 323         closedir(dir);
 324         return sra;
 325
 326  abort:
 327         if (dir)
 328                 closedir(dir);
 329         sysfs_free(sra);
 330         return NULL;
 331 }
 332
 333 int sysfs_attr_match(const char *attr, const char *str)
 334 {
 335         /* See if attr, read from a sysfs file, matches
 336          * str.  They must either be the same, or attr can
 337          * have a trailing newline or comma
 338          */
 339         while (*attr && *str && *attr == *str) {
 340                 attr++;
 341                 str++;
 342         }
 343
 344         if (*str || (*attr && *attr != ',' && *attr != '\n'))
 345                 return 0;
 346         return 1;
 347 }
 348
 349 int sysfs_match_word(const char *word, char **list)
 350 {
 351         int n;
 352         for (n=0; list[n]; n++)
 353                 if (sysfs_attr_match(word, list[n]))
 354                         break;
 355         return n;
 356 }
 357
 358 unsigned long long get_component_size(int fd)
 359 {
 360         /* Find out the component size of the array.
 361          * We cannot trust GET_ARRAY_INFO ioctl as it's
 362          * size field is only 32bits.
 363          * So look in /sys/block/mdXXX/md/component_size
 364          *
 365          * This returns in units of sectors.
 366          */
 367         struct stat stb;
 368         char fname[50];
 369         int n;
 370         if (fstat(fd, &stb)) return 0;
 371         if (major(stb.st_rdev) != (unsigned)get_mdp_major())
 372                 sprintf(fname, "/sys/block/md%d/md/component_size",
 373                         (int)minor(stb.st_rdev));
 374         else
 375                 sprintf(fname, "/sys/block/md_d%d/md/component_size",
 376                         (int)minor(stb.st_rdev)>>MdpMinorShift);
 377         fd = open(fname, O_RDONLY);
 378         if (fd < 0)
 379                 return 0;
 380         n = read(fd, fname, sizeof(fname));
 381         close(fd);
 382         if (n == sizeof(fname))
 383                 return 0;
 384         fname[n] = 0;
 385         return strtoull(fname, NULL, 10) * 2;
 386 }
 387
 388 int sysfs_set_str(struct mdinfo *sra, struct mdinfo *dev,
 389                   char *name, char *val)
 390 {
 391         char fname[50];
 392         unsigned int n;
 393         int fd;
 394
 395         sprintf(fname, "/sys/block/%s/md/%s/%s",
 396                 sra->sys_name, dev?dev->sys_name:"", name);
 397         fd = open(fname, O_WRONLY);
 398         if (fd < 0)
 399                 return -1;
 400         n = write(fd, val, strlen(val));
 401         close(fd);
 402         if (n != strlen(val)) {
 403                 dprintf(Name ": failed to write '%s' to '%s' (%s)\n",
 404                         val, fname, strerror(errno));
 405                 return -1;
 406         }
 407         return 0;
 408 }
 409
 410 int sysfs_set_num(struct mdinfo *sra, struct mdinfo *dev,
 411                   char *name, unsigned long long val)
 412 {
 413         char valstr[50];
 414         sprintf(valstr, "%llu", val);
 415         return sysfs_set_str(sra, dev, name, valstr);
 416 }
 417
 418 int sysfs_uevent(struct mdinfo *sra, char *event)
 419 {
 420         char fname[50];
 421         int n;
 422         int fd;
 423
 424         sprintf(fname, "/sys/block/%s/uevent",
 425                 sra->sys_name);
 426         fd = open(fname, O_WRONLY);
 427         if (fd < 0)
 428                 return -1;
 429         n = write(fd, event, strlen(event));
 430         close(fd);
 431         return 0;
 432 }
 433
 434 int sysfs_attribute_available(struct mdinfo *sra, struct mdinfo *dev, char *name)
 435 {
 436         char fname[50];
 437         struct stat st;
 438
 439         sprintf(fname, "/sys/block/%s/md/%s/%s",
 440                 sra->sys_name, dev?dev->sys_name:"", name);
 441
 442         return stat(fname, &st) == 0;
 443 }
 444
 445 int sysfs_get_fd(struct mdinfo *sra, struct mdinfo *dev,
 446                        char *name)
 447 {
 448         char fname[50];
 449         int fd;
 450
 451         sprintf(fname, "/sys/block/%s/md/%s/%s",
 452                 sra->sys_name, dev?dev->sys_name:"", name);
 453         fd = open(fname, O_RDWR);
 454         if (fd < 0)
 455                 fd = open(fname, O_RDONLY);
 456         return fd;
 457 }
 458
 459 int sysfs_fd_get_ll(int fd, unsigned long long *val)
 460 {
 461         char buf[50];
 462         int n;
 463         char *ep;
 464
 465         lseek(fd, 0, 0);
 466         n = read(fd, buf, sizeof(buf));
 467         if (n <= 0)
 468                 return -1;
 469         buf[n] = 0;
 470         *val = strtoull(buf, &ep, 0);
 471         if (ep == buf || (*ep != 0 && *ep != '\n' && *ep != ' '))
 472                 return -1;
 473         return 0;
 474 }
 475
 476 int sysfs_get_ll(struct mdinfo *sra, struct mdinfo *dev,
 477                        char *name, unsigned long long *val)
 478 {
 479         int n;
 480         int fd;
 481
 482         fd = sysfs_get_fd(sra, dev, name);
 483         if (fd < 0)
 484                 return -1;
 485         n = sysfs_fd_get_ll(fd, val);
 486         close(fd);
 487         return n;
 488 }
 489
 490 int sysfs_fd_get_str(int fd, char *val, int size)
 491 {
 492         int n;
 493
 494         lseek(fd, 0, 0);
 495         n = read(fd, val, size);
 496         if (n <= 0)
 497                 return -1;
 498         val[n] = 0;
 499         return n;
 500 }
 501
 502 int sysfs_get_str(struct mdinfo *sra, struct mdinfo *dev,
 503                        char *name, char *val, int size)
 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_str(fd, val, size);
 512         close(fd);
 513         return n;
 514 }
 515
 516 int sysfs_set_safemode(struct mdinfo *sra, unsigned long ms)
 517 {
 518         unsigned long sec;
 519         unsigned long msec;
 520         char delay[30];
 521
 522         sec = ms / 1000;
 523         msec = ms % 1000;
 524
 525         sprintf(delay, "%ld.%03ld\n", sec, msec);
 526         /*             this '\n' ^ needed for kernels older than 2.6.28 */
 527         return sysfs_set_str(sra, NULL, "safe_mode_delay", delay);
 528 }
 529
 530 int sysfs_set_array(struct mdinfo *info, int vers)
 531 {
 532         int rv = 0;
 533         char ver[100];
 534         int raid_disks = info->array.raid_disks;
 535
 536         ver[0] = 0;
 537         if (info->array.major_version == -1 &&
 538             info->array.minor_version == -2) {
 539                 strcat(strcpy(ver, "external:"), info->text_version);
 540
 541                 if ((vers % 100) < 2 ||
 542                     sysfs_set_str(info, NULL, "metadata_version",
 543                                   ver) < 0) {
 544                         fprintf(stderr, Name ": This kernel does not "
 545                                 "support external metadata.\n");
 546                         return 1;
 547                 }
 548         }
 549         if (info->array.level < 0)
 550                 return 0; /* FIXME */
 551         rv |= sysfs_set_str(info, NULL, "level",
 552                             map_num(pers, info->array.level));
 553         if (info->reshape_active && info->delta_disks != UnSet)
 554                 raid_disks -= info->delta_disks;
 555         rv |= sysfs_set_num(info, NULL, "raid_disks", raid_disks);
 556         rv |= sysfs_set_num(info, NULL, "chunk_size", info->array.chunk_size);
 557         rv |= sysfs_set_num(info, NULL, "layout", info->array.layout);
 558         rv |= sysfs_set_num(info, NULL, "component_size", info->component_size/2);
 559         if (info->custom_array_size) {
 560                 int rc;
 561
 562                 rc = sysfs_set_num(info, NULL, "array_size",
 563                                    info->custom_array_size/2);
 564                 if (rc && errno == ENOENT) {
 565                         fprintf(stderr, Name ": This kernel does not "
 566                                 "have the md/array_size attribute, "
 567                                 "the array may be larger than expected\n");
 568                         rc = 0;
 569                 }
 570                 rv |= rc;
 571         }
 572
 573         if (info->array.level > 0)
 574                 rv |= sysfs_set_num(info, NULL, "resync_start", info->resync_start);
 575
 576         if (info->reshape_active) {
 577                 rv |= sysfs_set_num(info, NULL, "reshape_position",
 578                                     info->reshape_progress);
 579                 rv |= sysfs_set_num(info, NULL, "chunk_size", info->new_chunk);
 580                 rv |= sysfs_set_num(info, NULL, "layout", info->new_layout);
 581                 rv |= sysfs_set_num(info, NULL, "raid_disks",
 582                                     info->array.raid_disks);
 583                 /* We don't set 'new_level' here.  That can only happen
 584                  * once the reshape completes.
 585                  */
 586         }
 587         return rv;
 588 }
 589
 590 int sysfs_add_disk(struct mdinfo *sra, struct mdinfo *sd, int resume)
 591 {
 592         char dv[PATH_MAX];
 593         char nm[PATH_MAX];
 594         char *dname;
 595         int rv;
 596
 597         sprintf(dv, "%d:%d", sd->disk.major, sd->disk.minor);
 598         rv = sysfs_set_str(sra, NULL, "new_dev", dv);
 599         if (rv)
 600                 return rv;
 601
 602         memset(nm, 0, sizeof(nm));
 603         sprintf(dv, "/sys/dev/block/%d:%d", sd->disk.major, sd->disk.minor);
 604         rv = readlink(dv, nm, sizeof(nm));
 605         if (rv <= 0)
 606                 return -1;
 607         nm[rv] = '\0';
 608         dname = strrchr(nm, '/');
 609         if (dname) dname++;
 610         strcpy(sd->sys_name, "dev-");
 611         strcpy(sd->sys_name+4, dname);
 612
 613         /* test write to see if 'recovery_start' is available */
 614         if (resume && sd->recovery_start < MaxSector &&
 615             sysfs_set_num(sra, sd, "recovery_start", 0)) {
 616                 sysfs_set_str(sra, sd, "state", "remove");
 617                 return -1;
 618         }
 619
 620         rv = sysfs_set_num(sra, sd, "offset", sd->data_offset);
 621         rv |= sysfs_set_num(sra, sd, "size", (sd->component_size+1) / 2);
 622         if (sra->array.level != LEVEL_CONTAINER) {
 623                 if (sd->recovery_start == MaxSector)
 624                         /* This can correctly fail if array isn't started,
 625                          * yet, so just ignore status for now.
 626                          */
 627                         sysfs_set_str(sra, sd, "state", "insync");
 628                 if (sd->disk.raid_disk >= 0)
 629                         rv |= sysfs_set_num(sra, sd, "slot", sd->disk.raid_disk);
 630                 if (resume)
 631                         sysfs_set_num(sra, sd, "recovery_start", sd->recovery_start);
 632         }
 633         return rv;
 634 }
 635
 636 #if 0
 637 int sysfs_disk_to_sg(int fd)
 638 {
 639         /* from an open block device, try find and open its corresponding
 640          * scsi_generic interface
 641          */
 642         struct stat st;
 643         char path[256];
 644         char sg_path[256];
 645         char sg_major_minor[8];
 646         char *c;
 647         DIR *dir;
 648         struct dirent *de;
 649         int major, minor, rv;
 650
 651         if (fstat(fd, &st))
 652                 return -1;
 653
 654         snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/device",
 655                  major(st.st_rdev), minor(st.st_rdev));
 656
 657         dir = opendir(path);
 658         if (!dir)
 659                 return -1;
 660
 661         de = readdir(dir);
 662         while (de) {
 663                 if (strncmp("scsi_generic:", de->d_name,
 664                             strlen("scsi_generic:")) == 0)
 665                         break;
 666                 de = readdir(dir);
 667         }
 668         closedir(dir);
 669
 670         if (!de)
 671                 return -1;
 672
 673         snprintf(sg_path, sizeof(sg_path), "%s/%s/dev", path, de->d_name);
 674         fd = open(sg_path, O_RDONLY);
 675         if (fd < 0)
 676                 return fd;
 677
 678         rv = read(fd, sg_major_minor, sizeof(sg_major_minor));
 679         close(fd);
 680         if (rv < 0)
 681                 return -1;
 682         else
 683                 sg_major_minor[rv - 1] = '\0';
 684
 685         c = strchr(sg_major_minor, ':');
 686         *c = '\0';
 687         c++;
 688         major = strtol(sg_major_minor, NULL, 10);
 689         minor = strtol(c, NULL, 10);
 690         snprintf(path, sizeof(path), "/dev/.tmp.md.%d:%d:%d",
 691                  (int) getpid(), major, minor);
 692         if (mknod(path, S_IFCHR|0600, makedev(major, minor))==0) {
 693                         fd = open(path, O_RDONLY);
 694                         unlink(path);
 695                         return fd;
 696         }
 697
 698         return -1;
 699 }
 700 #endif
 701
 702 int sysfs_disk_to_scsi_id(int fd, __u32 *id)
 703 {
 704         /* from an open block device, try to retrieve it scsi_id */
 705         struct stat st;
 706         char path[256];
 707         char *c1, *c2;
 708         DIR *dir;
 709         struct dirent *de;
 710
 711         if (fstat(fd, &st))
 712                 return 1;
 713
 714         snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/device/scsi_device",
 715                  major(st.st_rdev), minor(st.st_rdev));
 716
 717         dir = opendir(path);
 718         if (!dir)
 719                 return 1;
 720
 721         de = readdir(dir);
 722         while (de) {
 723                 if (strchr(de->d_name, ':'))
 724                         break;
 725                 de = readdir(dir);
 726         }
 727         closedir(dir);
 728
 729         if (!de)
 730                 return 1;
 731
 732         c1 = de->d_name;
 733         c2 = strchr(c1, ':');
 734         *c2 = '\0';
 735         *id = strtol(c1, NULL, 10) << 24; /* host */
 736         c1 = c2 + 1;
 737         c2 = strchr(c1, ':');
 738         *c2 = '\0';
 739         *id |= strtol(c1, NULL, 10) << 16; /* bus */
 740         c1 = c2 + 1;
 741         c2 = strchr(c1, ':');
 742         *c2 = '\0';
 743         *id |= strtol(c1, NULL, 10) << 8; /* target */
 744         c1 = c2 + 1;
 745         *id |= strtol(c1, NULL, 10); /* lun */
 746
 747         return 0;
 748 }
 749
 750
 751 int sysfs_unique_holder(int devnum, long rdev)
 752 {
 753         /* Check that devnum is a holder of rdev,
 754          * and is the only holder.
 755          * we should be locked against races by
 756          * an O_EXCL on devnum
 757          */
 758         DIR *dir;
 759         struct dirent *de;
 760         char dirname[100];
 761         char l;
 762         int found = 0;
 763         sprintf(dirname, "/sys/dev/block/%d:%d/holders",
 764                 major(rdev), minor(rdev));
 765         dir = opendir(dirname);
 766         errno = ENOENT;
 767         if (!dir)
 768                 return 0;
 769         l = strlen(dirname);
 770         while ((de = readdir(dir)) != NULL) {
 771                 char buf[10];
 772                 int n;
 773                 int mj, mn;
 774                 char c;
 775                 int fd;
 776
 777                 if (de->d_ino == 0)
 778                         continue;
 779                 if (de->d_name[0] == '.')
 780                         continue;
 781                 strcpy(dirname+l, "/");
 782                 strcat(dirname+l, de->d_name);
 783                 strcat(dirname+l, "/dev");
 784                 fd = open(dirname, O_RDONLY);
 785                 if (fd < 0) {
 786                         errno = ENOENT;
 787                         break;
 788                 }
 789                 n = read(fd, buf, sizeof(buf)-1);
 790                 close(fd);
 791                 buf[n] = 0;
 792                 if (sscanf(buf, "%d:%d%c", &mj, &mn, &c) != 3 ||
 793                     c != '\n') {
 794                         errno = ENOENT;
 795                         break;
 796                 }
 797                 if (mj != MD_MAJOR)
 798                         mn = -1-(mn>>6);
 799
 800                 if (devnum != mn) {
 801                         errno = EEXIST;
 802                         break;
 803                 }
 804                 found = 1;
 805         }
 806         closedir(dir);
 807         if (de)
 808                 return 0;
 809         else
 810                 return found;
 811 }
 812
 813 int sysfs_freeze_array(struct mdinfo *sra)
 814 {
 815         /* Try to freeze resync/rebuild on this array/container.
 816          * Return -1 if the array is busy,
 817          * return -2 container cannot be frozen,
 818          * return 0 if this kernel doesn't support 'frozen'
 819          * return 1 if it worked.
 820          */
 821         char buf[20];
 822
 823         if (!sysfs_attribute_available(sra, NULL, "sync_action"))
 824                 return 1; /* no sync_action == frozen */
 825         if (sysfs_get_str(sra, NULL, "sync_action", buf, 20) <= 0)
 826                 return 0;
 827         if (strcmp(buf, "idle\n") != 0 &&
 828             strcmp(buf, "frozen\n") != 0)
 829                 return -1;
 830         if (sysfs_set_str(sra, NULL, "sync_action", "frozen") < 0)
 831                 return 0;
 832         return 1;
 833 }