Assemble.c

   1 /*
   2  * mdadm - manage Linux "md" devices aka RAID arrays.
   3  *
   4  * Copyright (C) 2001-2002 Neil Brown <neilb@cse.unsw.edu.au>
   5  *
   6  *
   7  *    This program is free software; you can redistribute it and/or modify
   8  *    it under the terms of the GNU General Public License as published by
   9  *    the Free Software Foundation; either version 2 of the License, or
  10  *    (at your option) any later version.
  11  *
  12  *    This program is distributed in the hope that it will be useful,
  13  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *    GNU General Public License for more details.
  16  *
  17  *    You should have received a copy of the GNU General Public License
  18  *    along with this program; if not, write to the Free Software
  19  *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  *
  21  *    Author: Neil Brown
  22  *    Email: <neilb@cse.unsw.edu.au>
  23  *    Paper: Neil Brown
  24  *           School of Computer Science and Engineering
  25  *           The University of New South Wales
  26  *           Sydney, 2052
  27  *           Australia
  28  */
  29
  30 #include        "mdadm.h"
  31
  32 int Assemble(struct supertype *st, char *mddev, int mdfd,
  33              mddev_ident_t ident, char *conffile,
  34              mddev_dev_t devlist,
  35              int readonly, int runstop,
  36              char *update,
  37              int verbose, int force)
  38 {
  39         /*
  40          * The task of Assemble is to find a collection of
  41          * devices that should (according to their superblocks)
  42          * form an array, and to give this collection to the MD driver.
  43          * In Linux-2.4 and later, this involves submitting a
  44          * SET_ARRAY_INFO ioctl with no arg - to prepare
  45          * the array - and then submit a number of
  46          * ADD_NEW_DISK ioctls to add disks into
  47          * the array.  Finally RUN_ARRAY might
  48          * be submitted to start the array.
  49          *
  50          * Much of the work of Assemble is in finding and/or
  51          * checking the disks to make sure they look right.
  52          *
  53          * If mddev is not set, then scan must be set and we
  54          *  read through the config file for dev+uuid mapping
  55          *  We recurse, setting mddev, for each device that
  56          *    - isn't running
  57          *    - has a valid uuid (or any uuid if !uuidset)
  58          *
  59          * If mddev is set, we try to determine state of md.
  60          *   check version - must be at least 0.90.0
  61          *   check kernel version.  must be at least 2.4.
  62          *    If not, we can possibly fall back on START_ARRAY
  63          *   Try to GET_ARRAY_INFO.
  64          *     If possible, give up
  65          *     If not, try to STOP_ARRAY just to make sure
  66          *
  67          * If !uuidset and scan, look in conf-file for uuid
  68          *       If not found, give up
  69          * If !devlist and scan and uuidset, get list of devs from conf-file
  70          *
  71          * For each device:
  72          *   Check superblock - discard if bad
  73          *   Check uuid (set if we don't have one) - discard if no match
  74          *   Check superblock similarity if we have a superblock - discard if different
  75          *   Record events, devicenum
  76          * This should give us a list of devices for the array
  77          * We should collect the most recent event number
  78          *
  79          * Count disks with recent enough event count
  80          * While force && !enough disks
  81          *    Choose newest rejected disks, update event count
  82          *     mark clean and rewrite superblock
  83          * If recent kernel:
  84          *    SET_ARRAY_INFO
  85          *    foreach device with recent events : ADD_NEW_DISK
  86          *    if runstop == 1 || "enough" disks and runstop==0 -> RUN_ARRAY
  87          * If old kernel:
  88          *    Check the device numbers in superblock are right
  89          *    update superblock if any changes
  90          *    START_ARRAY
  91          *
  92          */
  93         int old_linux = 0;
  94         int vers;
  95         void *first_super = NULL, *super = NULL;
  96         struct {
  97                 char *devname;
  98                 unsigned int major, minor;
  99                 unsigned int oldmajor, oldminor;
 100                 long long events;
 101                 int uptodate;
 102                 int state;
 103                 int raid_disk;
 104         } *devices;
 105         int *best = NULL; /* indexed by raid_disk */
 106         unsigned int bestcnt = 0;
 107         int devcnt = 0;
 108         unsigned int okcnt, sparecnt;
 109         unsigned int req_cnt;
 110         unsigned int i;
 111         int most_recent = 0;
 112         int chosen_drive;
 113         int change = 0;
 114         int inargv = 0;
 115         int start_partial_ok = force || devlist==NULL;
 116         unsigned int num_devs;
 117         mddev_dev_t tmpdev;
 118         struct mdinfo info;
 119         struct mddev_ident_s ident2;
 120
 121         vers = md_get_version(mdfd);
 122         if (vers <= 0) {
 123                 fprintf(stderr, Name ": %s appears not to be an md device.\n", mddev);
 124                 return 1;
 125         }
 126         if (vers < 9000) {
 127                 fprintf(stderr, Name ": Assemble requires driver version 0.90.0 or later.\n"
 128                         "    Upgrade your kernel or try --build\n");
 129                 return 1;
 130         }
 131         if (get_linux_version() < 2004000)
 132                 old_linux = 1;
 133
 134         if (ioctl(mdfd, GET_ARRAY_INFO, &info.array)>=0) {
 135                 fprintf(stderr, Name ": device %s already active - cannot assemble it\n",
 136                         mddev);
 137                 return 1;
 138         }
 139         ioctl(mdfd, STOP_ARRAY, NULL); /* just incase it was started but has no content */
 140
 141         /*
 142          * If any subdevs are listed, then any that don't
 143          * match ident are discarded.  Remainder must all match and
 144          * become the array.
 145          * If no subdevs, then we scan all devices in the config file, but
 146          * there must be something in the identity
 147          */
 148
 149         if (!devlist &&
 150             ident->uuid_set == 0 &&
 151             ident->super_minor < 0 &&
 152             ident->devices == NULL) {
 153                 fprintf(stderr, Name ": No identity information available for %s - cannot assemble.\n",
 154                         mddev);
 155                 return 1;
 156         }
 157         if (devlist == NULL)
 158                 devlist = conf_get_devs(conffile);
 159         else inargv = 1;
 160
 161         tmpdev = devlist; num_devs = 0;
 162         while (tmpdev) {
 163                 num_devs++;
 164                 tmpdev = tmpdev->next;
 165         }
 166         devices = malloc(num_devs * sizeof(*devices));
 167
 168         if (!st && ident->st) st = ident->st;
 169
 170         if (verbose)
 171             fprintf(stderr, Name ": looking for devices for %s\n",
 172                     mddev);
 173
 174         while ( devlist) {
 175                 char *devname;
 176                 int dfd;
 177                 struct stat stb;
 178                 struct supertype *tst = st;
 179
 180                 devname = devlist->devname;
 181                 devlist = devlist->next;
 182
 183                 if (ident->devices &&
 184                     !match_oneof(ident->devices, devname)) {
 185                         if (inargv || verbose)
 186                                 fprintf(stderr, Name ": %s is not one of %s\n", devname, ident->devices);
 187                         continue;
 188                 }
 189
 190                 if (super) {
 191                         free(super);
 192                         super = NULL;
 193                 }
 194
 195                 dfd = open(devname, O_RDONLY|O_EXCL, 0);
 196                 if (dfd < 0) {
 197                         if (inargv || verbose)
 198                                 fprintf(stderr, Name ": cannot open device %s: %s\n",
 199                                         devname, strerror(errno));
 200                 } else if (fstat(dfd, &stb)< 0) {
 201                         /* Impossible! */
 202                         fprintf(stderr, Name ": fstat failed for %s: %s\n",
 203                                 devname, strerror(errno));
 204                         close(dfd);
 205                 } else if ((stb.st_mode & S_IFMT) != S_IFBLK) {
 206                         fprintf(stderr, Name ": %s is not a block device.\n",
 207                                 devname);
 208                         close(dfd);
 209                 } else if (!tst && (tst = guess_super(dfd)) == NULL) {
 210                         if (inargv || verbose)
 211                                 fprintf(stderr, Name ": no recogniseable superblock\n");
 212                 } else if (tst->ss->load_super(tst,dfd, &super, NULL)) {
 213                         if (inargv || verbose)
 214                                 fprintf( stderr, Name ": no RAID superblock on %s\n",
 215                                          devname);
 216                         close(dfd);
 217                 } else {
 218                         tst->ss->getinfo_super(&info, &ident2, super);
 219                         close(dfd);
 220                 }
 221
 222                 if (ident->uuid_set &&
 223                     (!super || same_uuid(info.uuid, ident->uuid, tst->ss->swapuuid)==0)) {
 224                         if (inargv || verbose)
 225                                 fprintf(stderr, Name ": %s has wrong uuid.\n",
 226                                         devname);
 227                         continue;
 228                 }
 229                 if (ident->name[0] &&
 230                     (!super || strncmp(ident2.name, ident->name, 32)!=0)) {
 231                         if (inargv || verbose)
 232                                 fprintf(stderr, Name ": %s has wrong name.\n",
 233                                         devname);
 234                         continue;
 235                 }
 236                 if (ident->super_minor != UnSet &&
 237                     (!super || ident->super_minor != info.array.md_minor)) {
 238                         if (inargv || verbose)
 239                                 fprintf(stderr, Name ": %s has wrong super-minor.\n",
 240                                         devname);
 241                         continue;
 242                 }
 243                 if (ident->level != UnSet &&
 244                     (!super|| ident->level != info.array.level)) {
 245                         if (inargv || verbose)
 246                                 fprintf(stderr, Name ": %s has wrong raid level.\n",
 247                                         devname);
 248                         continue;
 249                 }
 250                 if (ident->raid_disks != UnSet &&
 251                     (!super || ident->raid_disks!= info.array.raid_disks)) {
 252                         if (inargv || verbose)
 253                                 fprintf(stderr, Name ": %s requires wrong number of drives.\n",
 254                                         devname);
 255                         continue;
 256                 }
 257
 258                 /* If we are this far, then we are commited to this device.
 259                  * If the super_block doesn't exist, or doesn't match others,
 260                  * then we cannot continue
 261                  */
 262
 263                 if (!super) {
 264                         fprintf(stderr, Name ": %s has no superblock - assembly aborted\n",
 265                                 devname);
 266                         free(first_super);
 267                         return 1;
 268                 }
 269                 st = tst; /* commit to this format, if haven't already */
 270                 if (st->ss->compare_super(&first_super, super)) {
 271                         fprintf(stderr, Name ": superblock on %s doesn't match others - assembly aborted\n",
 272                                 devname);
 273                         free(super);
 274                         free(first_super);
 275                         return 1;
 276                 }
 277
 278                 /* looks like a good enough match to update the super block if needed */
 279                 if (update) {
 280                         /* prepare useful information in info structures */
 281                         struct stat stb2;
 282                         fstat(mdfd, &stb2);
 283                         info.array.md_minor = minor(stb2.st_rdev);
 284
 285                         st->ss->update_super(&info, super, update, devname, verbose);
 286
 287                         dfd = open(devname, O_RDWR|O_EXCL, 0);
 288                         if (dfd < 0)
 289                                 fprintf(stderr, Name ": Cannot open %s for superblock update\n",
 290                                         devname);
 291                         else if (st->ss->store_super(st, dfd, super))
 292                                 fprintf(stderr, Name ": Could not re-write superblock on %s.\n",
 293                                         devname);
 294                         if (dfd >= 0)
 295                                 close(dfd);
 296                 }
 297
 298                 if (verbose)
 299                         fprintf(stderr, Name ": %s is identified as a member of %s, slot %d.\n",
 300                                 devname, mddev, info.disk.raid_disk);
 301                 devices[devcnt].devname = devname;
 302                 devices[devcnt].major = major(stb.st_rdev);
 303                 devices[devcnt].minor = minor(stb.st_rdev);
 304                 devices[devcnt].oldmajor = info.disk.major;
 305                 devices[devcnt].oldminor = info.disk.minor;
 306                 devices[devcnt].events = info.events;
 307                 devices[devcnt].raid_disk = info.disk.raid_disk;
 308                 devices[devcnt].uptodate = 0;
 309                 devices[devcnt].state = info.disk.state;
 310                 if (most_recent < devcnt) {
 311                         if (devices[devcnt].events
 312                             > devices[most_recent].events)
 313                                 most_recent = devcnt;
 314                 }
 315                 if (info.array.level == -4)
 316                         /* with multipath, the raid_disk from the superblock is meaningless */
 317                         i = devcnt;
 318                 else
 319                         i = devices[devcnt].raid_disk;
 320                 if (i < 10000) {
 321                         if (i >= bestcnt) {
 322                                 unsigned int newbestcnt = i+10;
 323                                 int *newbest = malloc(sizeof(int)*newbestcnt);
 324                                 unsigned int c;
 325                                 for (c=0; c < newbestcnt; c++)
 326                                         if (c < bestcnt)
 327                                                 newbest[c] = best[c];
 328                                         else
 329                                                 newbest[c] = -1;
 330                                 if (best)free(best);
 331                                 best = newbest;
 332                                 bestcnt = newbestcnt;
 333                         }
 334                         if (best[i] == -1
 335                             || devices[best[i]].events < devices[devcnt].events)
 336                                 best[i] = devcnt;
 337                 }
 338                 devcnt++;
 339         }
 340
 341         if (super)
 342                 free(super);
 343         super = NULL;
 344
 345         if (update && strcmp(update, "byteorder")==0)
 346                 st->minor_version = 90;
 347
 348         if (devcnt == 0) {
 349                 fprintf(stderr, Name ": no devices found for %s\n",
 350                         mddev);
 351                 free(first_super);
 352                 return 1;
 353         }
 354
 355         st->ss->getinfo_super(&info, &ident2, first_super);
 356
 357         /* now we have some devices that might be suitable.
 358          * I wonder how many
 359          */
 360         okcnt = 0;
 361         sparecnt=0;
 362         for (i=0; i< bestcnt ;i++) {
 363                 int j = best[i];
 364                 int event_margin = !force;
 365                 if (j < 0) continue;
 366                 /* note: we ignore error flags in multipath arrays
 367                  * as they don't make sense
 368                  */
 369                 if (info.array.level != -4)
 370                         if (!(devices[j].state & (1<<MD_DISK_SYNC))) {
 371                                 if (!(devices[j].state & (1<<MD_DISK_FAULTY)))
 372                                         sparecnt++;
 373                                 continue;
 374                         }
 375                 if (devices[j].events+event_margin >=
 376                     devices[most_recent].events) {
 377                         devices[j].uptodate = 1;
 378                         if (i < info.array.raid_disks)
 379                                 okcnt++;
 380                         else
 381                                 sparecnt++;
 382                 }
 383         }
 384         while (force && !enough(info.array.level, info.array.raid_disks, okcnt)) {
 385                 /* Choose the newest best drive which is
 386                  * not up-to-date, update the superblock
 387                  * and add it.
 388                  */
 389                 int fd;
 390                 chosen_drive = -1;
 391                 for (i=0; i<info.array.raid_disks && i < bestcnt; i++) {
 392                         int j = best[i];
 393                         if (j>=0 &&
 394                             !devices[j].uptodate &&
 395                             devices[j].events > 0 &&
 396                             (chosen_drive < 0 ||
 397                              devices[j].events > devices[chosen_drive].events))
 398                                 chosen_drive = j;
 399                 }
 400                 if (chosen_drive < 0)
 401                         break;
 402                 fprintf(stderr, Name ": forcing event count in %s(%d) from %d upto %d\n",
 403                         devices[chosen_drive].devname, devices[chosen_drive].raid_disk,
 404                         (int)(devices[chosen_drive].events),
 405                         (int)(devices[most_recent].events));
 406                 fd = open(devices[chosen_drive].devname, O_RDWR|O_EXCL);
 407                 if (fd < 0) {
 408                         fprintf(stderr, Name ": Couldn't open %s for write - not updating\n",
 409                                 devices[chosen_drive].devname);
 410                         devices[chosen_drive].events = 0;
 411                         continue;
 412                 }
 413                 if (st->ss->load_super(st,fd, &super, NULL)) {
 414                         close(fd);
 415                         fprintf(stderr, Name ": RAID superblock disappeared from %s - not updating.\n",
 416                                 devices[chosen_drive].devname);
 417                         devices[chosen_drive].events = 0;
 418                         continue;
 419                 }
 420                 info.events = devices[most_recent].events;
 421                 st->ss->update_super(&info, super, "force", devices[chosen_drive].devname, verbose);
 422
 423                 if (st->ss->store_super(st, fd, super)) {
 424                         close(fd);
 425                         fprintf(stderr, Name ": Could not re-write superblock on %s\n",
 426                                 devices[chosen_drive].devname);
 427                         devices[chosen_drive].events = 0;
 428                         free(super);
 429                         continue;
 430                 }
 431                 close(fd);
 432                 devices[chosen_drive].events = devices[most_recent].events;
 433                 devices[chosen_drive].uptodate = 1;
 434                 okcnt++;
 435                 free(super);
 436         }
 437
 438         /* Now we want to look at the superblock which the kernel will base things on
 439          * and compare the devices that we think are working with the devices that the
 440          * superblock thinks are working.
 441          * If there are differences and --force is given, then update this chosen
 442          * superblock.
 443          */
 444         chosen_drive = -1;
 445         super = NULL;
 446         for (i=0; chosen_drive < 0 && i<bestcnt; i++) {
 447                 int j = best[i];
 448                 int fd;
 449
 450                 if (j<0)
 451                         continue;
 452                 if (!devices[j].uptodate)
 453                         continue;
 454                 chosen_drive = j;
 455                 if ((fd=open(devices[j].devname, O_RDONLY|O_EXCL))< 0) {
 456                         fprintf(stderr, Name ": Cannot open %s: %s\n",
 457                                 devices[j].devname, strerror(errno));
 458                         return 1;
 459                 }
 460                 if (st->ss->load_super(st,fd, &super, NULL)) {
 461                         close(fd);
 462                         fprintf(stderr, Name ": RAID superblock has disappeared from %s\n",
 463                                 devices[j].devname);
 464                         return 1;
 465                 }
 466                 close(fd);
 467         }
 468         if (super == NULL) {
 469                 fprintf(stderr, Name ": No suitable drives found for %s\n", mddev);
 470                 return 1;
 471         }
 472         st->ss->getinfo_super(&info, &ident2, super);
 473         for (i=0; i<bestcnt; i++) {
 474                 int j = best[i];
 475                 unsigned int desired_state;
 476
 477                 if (i < info.array.raid_disks)
 478                         desired_state = (1<<MD_DISK_ACTIVE) | (1<<MD_DISK_SYNC);
 479                 else
 480                         desired_state = 0;
 481
 482                 if (j<0)
 483                         continue;
 484                 if (!devices[j].uptodate)
 485                         continue;
 486                 info.disk.number = i;
 487                 info.disk.raid_disk = i;
 488                 info.disk.state = desired_state;
 489
 490                 if (devices[j].uptodate &&
 491                     st->ss->update_super(&info, super, "assemble", NULL, 0)) {
 492                         if (force) {
 493                                 fprintf(stderr, Name ": "
 494                                         "clearing FAULTY flag for device %d in %s for %s\n",
 495                                         j, mddev, devices[j].devname);
 496                                 change = 1;
 497                         } else {
 498                                 fprintf(stderr, Name ": "
 499                                         "device %d in %s has wrong state in superblock, but %s seems ok\n",
 500                                         i, mddev, devices[j].devname);
 501                         }
 502                 }
 503 #if 0
 504                 if (!devices[j].uptodate &&
 505                     !(super.disks[i].state & (1 << MD_DISK_FAULTY))) {
 506                         fprintf(stderr, Name ": devices %d of %s is not marked FAULTY in superblock, but cannot be found\n",
 507                                 i, mddev);
 508                 }
 509 #endif
 510         }
 511         if (force && okcnt == info.array.raid_disks-1) {
 512                 /* FIXME check event count */
 513                 change += st->ss->update_super(&info, super, "force",
 514                                         devices[chosen_drive].devname, 0);
 515         }
 516
 517         if (change) {
 518                 int fd;
 519                 fd = open(devices[chosen_drive].devname, O_RDWR|O_EXCL);
 520                 if (fd < 0) {
 521                         fprintf(stderr, Name ": Could open %s for write - cannot Assemble array.\n",
 522                                 devices[chosen_drive].devname);
 523                         return 1;
 524                 }
 525                 if (st->ss->store_super(st, fd, super)) {
 526                         close(fd);
 527                         fprintf(stderr, Name ": Could not re-write superblock on %s\n",
 528                                 devices[chosen_drive].devname);
 529                         return 1;
 530                 }
 531                 close(fd);
 532         }
 533
 534         /* count number of in-sync devices according to the superblock.
 535          * We must have this number to start the array without -s or -R
 536          */
 537         req_cnt = info.array.working_disks;
 538
 539         /* Almost ready to actually *do* something */
 540         if (!old_linux) {
 541                 int rv;
 542                 if ((vers % 100) >= 1) { /* can use different versions */
 543                         mdu_array_info_t inf;
 544                         memset(&inf, 0, sizeof(inf));
 545                         inf.major_version = st->ss->major;
 546                         inf.minor_version = st->minor_version;
 547                         rv = ioctl(mdfd, SET_ARRAY_INFO, &inf);
 548                 } else
 549                         rv = ioctl(mdfd, SET_ARRAY_INFO, NULL);
 550
 551                 if (rv) {
 552                         fprintf(stderr, Name ": SET_ARRAY_INFO failed for %s: %s\n",
 553                                 mddev, strerror(errno));
 554                         return 1;
 555                 }
 556                 if (ident->bitmap_fd >= 0) {
 557                         if (ioctl(mdfd, SET_BITMAP_FILE, ident->bitmap_fd) != 0) {
 558                                 fprintf(stderr, Name ": SET_BITMAP_FILE failed.\n");
 559                                 return 1;
 560                         }
 561                 }
 562
 563                 /* First, add the raid disks, but add the chosen one last */
 564                 for (i=0; i<= bestcnt; i++) {
 565                         int j;
 566                         if (i < bestcnt) {
 567                                 j = best[i];
 568                                 if (j == chosen_drive)
 569                                         continue;
 570                         } else
 571                                 j = chosen_drive;
 572
 573                         if (j >= 0 /* && devices[j].uptodate */) {
 574                                 mdu_disk_info_t disk;
 575                                 memset(&disk, 0, sizeof(disk));
 576                                 disk.major = devices[j].major;
 577                                 disk.minor = devices[j].minor;
 578                                 if (ioctl(mdfd, ADD_NEW_DISK, &disk)!=0) {
 579                                         fprintf(stderr, Name ": failed to add %s to %s: %s\n",
 580                                                 devices[j].devname,
 581                                                 mddev,
 582                                                 strerror(errno));
 583                                         if (i < info.array.raid_disks || i == bestcnt)
 584                                                 okcnt--;
 585                                         else
 586                                                 sparecnt--;
 587                                 } else if (verbose)
 588                                         fprintf(stderr, Name ": added %s to %s as %d\n",
 589                                                 devices[j].devname, mddev, devices[j].raid_disk);
 590                         } else if (verbose && i < info.array.raid_disks)
 591                                 fprintf(stderr, Name ": no uptodate device for slot %d of %s\n",
 592                                         i, mddev);
 593                 }
 594
 595                 if (runstop == 1 ||
 596                     (runstop == 0 &&
 597                      ( enough(info.array.level, info.array.raid_disks, okcnt) &&
 598                        (okcnt >= req_cnt || start_partial_ok)
 599                              ))) {
 600                         if (ioctl(mdfd, RUN_ARRAY, NULL)==0) {
 601                                 fprintf(stderr, Name ": %s has been started with %d drive%s",
 602                                         mddev, okcnt, okcnt==1?"":"s");
 603                                 if (okcnt < info.array.raid_disks)
 604                                         fprintf(stderr, " (out of %d)", info.array.raid_disks);
 605                                 if (sparecnt)
 606                                         fprintf(stderr, " and %d spare%s", sparecnt, sparecnt==1?"":"s");
 607                                 fprintf(stderr, ".\n");
 608                                 return 0;
 609                         }
 610                         fprintf(stderr, Name ": failed to RUN_ARRAY %s: %s\n",
 611                                 mddev, strerror(errno));
 612                         return 1;
 613                 }
 614                 if (runstop == -1) {
 615                         fprintf(stderr, Name ": %s assembled from %d drive%s, but not started.\n",
 616                                 mddev, okcnt, okcnt==1?"":"s");
 617                         return 0;
 618                 }
 619                 fprintf(stderr, Name ": %s assembled from %d drive%s", mddev, okcnt, okcnt==1?"":"s");
 620                 if (sparecnt)
 621                         fprintf(stderr, " and %d spare%s", sparecnt, sparecnt==1?"":"s");
 622                 if (!enough(info.array.level, info.array.raid_disks, okcnt))
 623                         fprintf(stderr, " - not enough to start the array.\n");
 624                 else {
 625                         if (req_cnt == info.array.raid_disks)
 626                                 fprintf(stderr, " - need all %d to start it", req_cnt);
 627                         else
 628                                 fprintf(stderr, " - need %d of %d to start", req_cnt, info.array.raid_disks);
 629                         fprintf(stderr, " (use --run to insist).\n");
 630                 }
 631                 return 1;
 632         } else {
 633                 /* The "chosen_drive" is a good choice, and if necessary, the superblock has
 634                  * been updated to point to the current locations of devices.
 635                  * so we can just start the array
 636                  */
 637                 unsigned long dev;
 638                 dev = makedev(devices[chosen_drive].major,
 639                             devices[chosen_drive].minor);
 640                 if (ioctl(mdfd, START_ARRAY, dev)) {
 641                     fprintf(stderr, Name ": Cannot start array: %s\n",
 642                             strerror(errno));
 643                 }
 644
 645         }
 646         return 0;
 647 }