monitor.c

   1
   2 #include "mdadm.h"
   3 #include "mdmon.h"
   4
   5 #include <sys/select.h>
   6 #include <signal.h>
   7
   8 static char *array_states[] = {
   9         "clear", "inactive", "suspended", "readonly", "read-auto",
  10         "clean", "active", "write-pending", "active-idle", NULL };
  11 static char *sync_actions[] = {
  12         "idle", "reshape", "resync", "recover", "check", "repair", NULL
  13 };
  14
  15 static int write_attr(char *attr, int fd)
  16 {
  17         return write(fd, attr, strlen(attr));
  18 }
  19
  20 static void add_fd(fd_set *fds, int *maxfd, int fd)
  21 {
  22         if (fd < 0)
  23                 return;
  24         if (fd > *maxfd)
  25                 *maxfd = fd;
  26         FD_SET(fd, fds);
  27 }
  28
  29 static int read_attr(char *buf, int len, int fd)
  30 {
  31         int n;
  32
  33         if (fd < 0) {
  34                 buf[0] = 0;
  35                 return 0;
  36         }
  37         lseek(fd, 0, 0);
  38         n = read(fd, buf, len - 1);
  39
  40         if (n <= 0) {
  41                 buf[0] = 0;
  42                 return 0;
  43         }
  44         buf[n] = 0;
  45         if (buf[n-1] == '\n')
  46                 buf[n-1] = 0;
  47         return n;
  48 }
  49
  50
  51 static int get_resync_start(struct active_array *a)
  52 {
  53         char buf[30];
  54         int n;
  55
  56         n = read_attr(buf, 30, a->resync_start_fd);
  57         if (n <= 0)
  58                 return n;
  59
  60         a->resync_start = strtoull(buf, NULL, 10);
  61
  62         return 1;
  63 }
  64
  65 static int attr_match(const char *attr, const char *str)
  66 {
  67         /* See if attr, read from a sysfs file, matches
  68          * str.  They must either be the same, or attr can
  69          * have a trailing newline or comma
  70          */
  71         while (*attr && *str && *attr == *str) {
  72                 attr++;
  73                 str++;
  74         }
  75
  76         if (*str || (*attr && *attr != ',' && *attr != '\n'))
  77                 return 0;
  78         return 1;
  79 }
  80
  81 static int match_word(const char *word, char **list)
  82 {
  83         int n;
  84         for (n=0; list[n]; n++)
  85                 if (attr_match(word, list[n]))
  86                         break;
  87         return n;
  88 }
  89
  90 static enum array_state read_state(int fd)
  91 {
  92         char buf[20];
  93         int n = read_attr(buf, 20, fd);
  94
  95         if (n <= 0)
  96                 return bad_word;
  97         return (enum array_state) match_word(buf, array_states);
  98 }
  99
 100 static enum sync_action read_action( int fd)
 101 {
 102         char buf[20];
 103         int n = read_attr(buf, 20, fd);
 104
 105         if (n <= 0)
 106                 return bad_action;
 107         return (enum sync_action) match_word(buf, sync_actions);
 108 }
 109
 110 int read_dev_state(int fd)
 111 {
 112         char buf[60];
 113         int n = read_attr(buf, 60, fd);
 114         char *cp;
 115         int rv = 0;
 116
 117         if (n <= 0)
 118                 return 0;
 119
 120         cp = buf;
 121         while (cp) {
 122                 if (attr_match(cp, "faulty"))
 123                         rv |= DS_FAULTY;
 124                 if (attr_match(cp, "in_sync"))
 125                         rv |= DS_INSYNC;
 126                 if (attr_match(cp, "write_mostly"))
 127                         rv |= DS_WRITE_MOSTLY;
 128                 if (attr_match(cp, "spare"))
 129                         rv |= DS_SPARE;
 130                 if (attr_match(cp, "blocked"))
 131                         rv |= DS_BLOCKED;
 132                 cp = strchr(cp, ',');
 133                 if (cp)
 134                         cp++;
 135         }
 136         return rv;
 137 }
 138
 139 static void signal_manager(void)
 140 {
 141         kill(getpid(), SIGUSR1);
 142 }
 143
 144 /* Monitor a set of active md arrays - all of which share the
 145  * same metadata - and respond to events that require
 146  * metadata update.
 147  *
 148  * New arrays are detected by another thread which allocates
 149  * required memory and attaches the data structure to our list.
 150  *
 151  * Events:
 152  *  Array stops.
 153  *    This is detected by array_state going to 'clear' or 'inactive'.
 154  *    while we thought it was active.
 155  *    Response is to mark metadata as clean and 'clear' the array(??)
 156  *  write-pending
 157  *    array_state if 'write-pending'
 158  *    We mark metadata as 'dirty' then set array to 'active'.
 159  *  active_idle
 160  *    Either ignore, or mark clean, then mark metadata as clean.
 161  *
 162  *  device fails
 163  *    detected by rd-N/state reporting "faulty"
 164  *    mark device as 'failed' in metadata, let the kernel release the
 165  *    device by writing '-blocked' to rd/state, and finally write 'remove' to
 166  *    rd/state.  Before a disk can be replaced it must be failed and removed
 167  *    from all container members, this will be preemptive for the other
 168  *    arrays... safe?
 169  *
 170  *  sync completes
 171  *    sync_action was 'resync' and becomes 'idle' and resync_start becomes
 172  *    MaxSector
 173  *    Notify metadata that sync is complete.
 174  *    "Deal with Degraded"
 175  *
 176  *  recovery completes
 177  *    sync_action changes from 'recover' to 'idle'
 178  *    Check each device state and mark metadata if 'faulty' or 'in_sync'.
 179  *    "Deal with Degraded"
 180  *
 181  *  deal with degraded array
 182  *    We only do this when first noticing the array is degraded.
 183  *    This can be when we first see the array, when sync completes or
 184  *    when recovery completes.
 185  *
 186  *    Check if number of failed devices suggests recovery is needed, and
 187  *    skip if not.
 188  *    Ask metadata for a spare device
 189  *    Add device as not in_sync and give a role
 190  *    Update metadata.
 191  *    Start recovery.
 192  *
 193  *  deal with resync
 194  *    This only happens on finding a new array... mdadm will have set
 195  *    'resync_start' to the correct value.  If 'resync_start' indicates that an
 196  *    resync needs to occur set the array to the 'active' state rather than the
 197  *    initial read-auto state.
 198  *
 199  *
 200  *
 201  * We wait for a change (poll/select) on array_state, sync_action, and
 202  * each rd-X/state file.
 203  * When we get any change, we check everything.  So read each state file,
 204  * then decide what to do.
 205  *
 206  * The core action is to write new metadata to all devices in the array.
 207  * This is done at most once on any wakeup.
 208  * After that we might:
 209  *   - update the array_state
 210  *   - set the role of some devices.
 211  *   - request a sync_action
 212  *
 213  */
 214
 215 static int read_and_act(struct active_array *a)
 216 {
 217         int check_degraded;
 218         int deactivate = 0;
 219         struct mdinfo *mdi;
 220
 221         a->next_state = bad_word;
 222         a->next_action = bad_action;
 223
 224         a->curr_state = read_state(a->info.state_fd);
 225         a->curr_action = read_action(a->action_fd);
 226         for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
 227                 mdi->next_state = 0;
 228                 if (mdi->state_fd > 0)
 229                         mdi->curr_state = read_dev_state(mdi->state_fd);
 230         }
 231
 232         if (a->curr_state <= inactive &&
 233             a->prev_state > inactive) {
 234                 /* array has been stopped */
 235                 a->container->ss->set_array_state(a, 1);
 236                 a->next_state = clear;
 237                 deactivate = 1;
 238         }
 239         if (a->curr_state == write_pending) {
 240                 get_resync_start(a);
 241                 a->container->ss->set_array_state(a, 0);
 242                 a->next_state = active;
 243         }
 244         if (a->curr_state == active_idle) {
 245                 /* Set array to 'clean' FIRST, then
 246                  * a->ss->mark_clean(a, ~0ULL);
 247                  * just ignore for now.
 248                  */
 249         }
 250
 251         if (a->curr_state == readonly) {
 252                 /* Well, I'm ready to handle things, so
 253                  * read-auto is OK. FIXME what if we really want
 254                  * readonly ???
 255                  */
 256                 get_resync_start(a);
 257                 printf("Found a readonly array at %llu\n", a->resync_start);
 258                 if (a->resync_start == ~0ULL)
 259                         a->next_state = read_auto; /* array is clean */
 260                 else {
 261                         a->container->ss->set_array_state(a, 0);
 262                         a->next_state = active;
 263                 }
 264         }
 265
 266         if (a->curr_action == idle &&
 267             a->prev_action == resync) {
 268                 /* A resync has finished.  The endpoint is recorded in
 269                  * 'sync_start'.  We don't update the metadata
 270                  * until the array goes inactive or readonly though.
 271                  * Just check if we need to fiddle spares.
 272                  */
 273                 get_resync_start(a);
 274                 a->container->ss->set_array_state(a, 0);
 275                 check_degraded = 1;
 276         }
 277
 278         if (a->curr_action == idle &&
 279             a->prev_action == recover) {
 280                 for (mdi = a->info.devs ; mdi ; mdi = mdi->next) {
 281                         a->container->ss->set_disk(a, mdi->disk.raid_disk,
 282                                                    mdi->curr_state);
 283                         if (! (mdi->curr_state & DS_INSYNC))
 284                                 check_degraded = 1;
 285                 }
 286         }
 287
 288
 289         for (mdi = a->info.devs ; mdi ; mdi = mdi->next) {
 290                 if (mdi->curr_state & DS_FAULTY) {
 291                         a->container->ss->set_disk(a, mdi->disk.raid_disk,
 292                                                    mdi->curr_state);
 293                         check_degraded = 1;
 294                         mdi->next_state = DS_REMOVE;
 295                 }
 296         }
 297
 298         if (check_degraded) {
 299                 // FIXME;
 300         }
 301
 302         a->container->ss->sync_metadata(a);
 303
 304         /* Effect state changes in the array */
 305         if (a->next_state != bad_word)
 306                 write_attr(array_states[a->next_state], a->info.state_fd);
 307         if (a->next_action != bad_action)
 308                 write_attr(sync_actions[a->next_action], a->action_fd);
 309         for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
 310                 if (mdi->next_state == DS_REMOVE && mdi->state_fd > 0) {
 311                         int remove_err;
 312
 313                         write_attr("-blocked", mdi->state_fd);
 314                         /* the kernel may not be able to immediately remove the
 315                          * disk, we can simply wait until the next event to try
 316                          * again.
 317                          */
 318                         remove_err = write_attr("remove", mdi->state_fd);
 319                         if (!remove_err) {
 320                                 close(mdi->state_fd);
 321                                 mdi->state_fd = -1;
 322                         }
 323                 }
 324                 if (mdi->next_state & DS_INSYNC)
 325                         write_attr("+in_sync", mdi->state_fd);
 326         }
 327
 328         /* move curr_ to prev_ */
 329         a->prev_state = a->curr_state;
 330
 331         a->prev_action = a->curr_action;
 332
 333         for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
 334                 mdi->prev_state = mdi->curr_state;
 335                 mdi->next_state = 0;
 336         }
 337
 338         if (deactivate)
 339                 a->container = NULL;
 340
 341         return 1;
 342 }
 343
 344 static struct mdinfo *
 345 find_device(struct active_array *a, int major, int minor)
 346 {
 347         struct mdinfo *mdi;
 348
 349         for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
 350                 if (mdi->disk.major == major && mdi->disk.minor == minor)
 351                         return mdi;
 352
 353         return NULL;
 354 }
 355
 356 static void reconcile_failed(struct active_array *aa, struct mdinfo *failed)
 357 {
 358         struct active_array *a;
 359         struct mdinfo *victim;
 360
 361         for (a = aa; a; a = a->next) {
 362                 if (!a->container)
 363                         continue;
 364                 victim = find_device(a, failed->disk.major, failed->disk.minor);
 365                 if (!victim)
 366                         continue;
 367
 368                 if (!(victim->curr_state & DS_FAULTY))
 369                         write_attr("faulty", victim->state_fd);
 370         }
 371 }
 372
 373 static int handle_remove_device(struct md_remove_device_cmd *cmd, struct active_array *aa)
 374 {
 375         struct active_array *a;
 376         struct mdinfo *victim;
 377         int rv;
 378
 379         /* scan all arrays for the given device, if ->state_fd is closed (-1)
 380          * in all cases then mark the disk as removed in the metadata.
 381          * Otherwise reply that it is busy.
 382          */
 383
 384         /* pass1 check that it is not in use anywhere */
 385         /* note: we are safe from re-adds as long as the device exists in the
 386          * container
 387          */
 388         for (a = aa; a; a = a->next) {
 389                 if (!a->container)
 390                         continue;
 391                 victim = find_device(a, major(cmd->rdev), minor(cmd->rdev));
 392                 if (!victim)
 393                         continue;
 394                 if (victim->state_fd > 0)
 395                         return -EBUSY;
 396         }
 397
 398         /* pass2 schedule and process removal per array */
 399         for (a = aa; a; a = a->next) {
 400                 if (!a->container)
 401                         continue;
 402                 victim = find_device(a, major(cmd->rdev), minor(cmd->rdev));
 403                 if (!victim)
 404                         continue;
 405                 victim->curr_state |= DS_REMOVE;
 406                 rv = read_and_act(a);
 407                 if (rv < 0)
 408                         return rv;
 409         }
 410
 411         return 0;
 412 }
 413
 414 static int handle_pipe(struct md_generic_cmd *cmd, struct active_array *aa)
 415 {
 416         switch (cmd->action) {
 417         case md_action_ping_monitor:
 418                 return 0;
 419         case md_action_remove_device:
 420                 return handle_remove_device((void *) cmd, aa);
 421         }
 422
 423         return -1;
 424 }
 425
 426 static int wait_and_act(struct supertype *container, int pfd,
 427                         int monfd, int nowait)
 428 {
 429         fd_set rfds;
 430         int maxfd = 0;
 431         struct active_array **aap = &container->arrays;
 432         struct active_array *a, **ap;
 433         int rv;
 434         struct mdinfo *mdi;
 435
 436         FD_ZERO(&rfds);
 437
 438         add_fd(&rfds, &maxfd, pfd);
 439         for (ap = aap ; *ap ;) {
 440                 a = *ap;
 441                 /* once an array has been deactivated we want to
 442                  * ask the manager to discard it.
 443                  */
 444                 if (!a->container) {
 445                         if (discard_this) {
 446                                 ap = &(*ap)->next;
 447                                 continue;
 448                         }
 449                         *ap = a->next;
 450                         a->next = NULL;
 451                         discard_this = a;
 452                         signal_manager();
 453                         continue;
 454                 }
 455
 456                 add_fd(&rfds, &maxfd, a->info.state_fd);
 457                 add_fd(&rfds, &maxfd, a->action_fd);
 458                 for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
 459                         add_fd(&rfds, &maxfd, mdi->state_fd);
 460
 461                 ap = &(*ap)->next;
 462         }
 463
 464         if (manager_ready && *aap == NULL) {
 465                 /* No interesting arrays. Lets see about exiting.
 466                  * Note that blocking at this point is not a problem
 467                  * as there are no active arrays, there is nothing that
 468                  * we need to be ready to do.
 469                  */
 470                 int fd = open(container->device_name, O_RDONLY|O_EXCL);
 471                 if (fd >= 0 || errno != EBUSY) {
 472                         /* OK, we are safe to leave */
 473                         exit_now = 1;
 474                         signal_manager();
 475                         remove_pidfile(container->devname);
 476                         exit(0);
 477                 }
 478         }
 479
 480         if (!nowait) {
 481                 rv = select(maxfd+1, &rfds, NULL, NULL, NULL);
 482
 483                 if (rv <= 0)
 484                         return rv;
 485
 486                 if (FD_ISSET(pfd, &rfds)) {
 487                         int err = -1;
 488
 489                         if (read(pfd, &err, 1) > 0)
 490                                 err = handle_pipe(active_cmd, *aap);
 491                         write(monfd, &err, 1);
 492                 }
 493         }
 494
 495         for (a = *aap; a ; a = a->next) {
 496                 if (a->replaces && !discard_this) {
 497                         struct active_array **ap;
 498                         for (ap = &a->next; *ap && *ap != a->replaces;
 499                              ap = & (*ap)->next)
 500                                 ;
 501                         if (*ap)
 502                                 *ap = (*ap)->next;
 503                         discard_this = a->replaces;
 504                         a->replaces = NULL;
 505                         signal_manager();
 506                 }
 507                 if (a->container)
 508                         rv += read_and_act(a);
 509         }
 510
 511         /* propagate failures across container members */
 512         for (a = *aap; a ; a = a->next) {
 513                 if (!a->container)
 514                         continue;
 515                 for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
 516                         if (mdi->curr_state & DS_FAULTY)
 517                                 reconcile_failed(*aap, mdi);
 518         }
 519
 520         return rv;
 521 }
 522
 523 void do_monitor(struct supertype *container)
 524 {
 525         int rv;
 526         int first = 1;
 527         do {
 528                 rv = wait_and_act(container, container->mgr_pipe[0],
 529                                   container->mon_pipe[1], first);
 530                 first = 0;
 531         } while (rv >= 0);
 532 }