monitor.c

   1 /*
   2  * mdmon - monitor external metadata arrays
   3  *
   4  * Copyright (C) 2007-2009 Neil Brown <neilb@suse.de>
   5  * Copyright (C) 2007-2009 Intel Corporation
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms and conditions of the GNU General Public License,
   9  * version 2, as published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14  * more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along with
  17  * this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 #include "mdadm.h"
  22 #include "mdmon.h"
  23 #include <sys/syscall.h>
  24 #include <sys/select.h>
  25 #include <signal.h>
  26
  27 static char *array_states[] = {
  28         "clear", "inactive", "suspended", "readonly", "read-auto",
  29         "clean", "active", "write-pending", "active-idle", NULL };
  30 static char *sync_actions[] = {
  31         "idle", "reshape", "resync", "recover", "check", "repair", NULL
  32 };
  33
  34 static int write_attr(char *attr, int fd)
  35 {
  36         return write(fd, attr, strlen(attr));
  37 }
  38
  39 static void add_fd(fd_set *fds, int *maxfd, int fd)
  40 {
  41         if (fd < 0)
  42                 return;
  43         if (fd > *maxfd)
  44                 *maxfd = fd;
  45         FD_SET(fd, fds);
  46 }
  47
  48 static int read_attr(char *buf, int len, int fd)
  49 {
  50         int n;
  51
  52         if (fd < 0) {
  53                 buf[0] = 0;
  54                 return 0;
  55         }
  56         lseek(fd, 0, 0);
  57         n = read(fd, buf, len - 1);
  58
  59         if (n <= 0) {
  60                 buf[0] = 0;
  61                 return 0;
  62         }
  63         buf[n] = 0;
  64         if (buf[n-1] == '\n')
  65                 buf[n-1] = 0;
  66         return n;
  67 }
  68
  69 static unsigned long long read_resync_start(int fd)
  70 {
  71         char buf[30];
  72         int n;
  73
  74         n = read_attr(buf, 30, fd);
  75         if (n <= 0)
  76                 return 0;
  77         if (strncmp(buf, "none", 4) == 0)
  78                 return MaxSector;
  79         else
  80                 return strtoull(buf, NULL, 10);
  81 }
  82
  83 static unsigned long long read_sync_completed(int fd)
  84 {
  85         unsigned long long val;
  86         char buf[50];
  87         int n;
  88         char *ep;
  89
  90         n = read_attr(buf, 50, fd);
  91
  92         if (n <= 0)
  93                 return 0;
  94         buf[n] = 0;
  95         val = strtoull(buf, &ep, 0);
  96         if (ep == buf || (*ep != 0 && *ep != '\n' && *ep != ' '))
  97                 return 0;
  98         return val;
  99 }
 100
 101 static enum array_state read_state(int fd)
 102 {
 103         char buf[20];
 104         int n = read_attr(buf, 20, fd);
 105
 106         if (n <= 0)
 107                 return bad_word;
 108         return (enum array_state) sysfs_match_word(buf, array_states);
 109 }
 110
 111 static enum sync_action read_action( int fd)
 112 {
 113         char buf[20];
 114         int n = read_attr(buf, 20, fd);
 115
 116         if (n <= 0)
 117                 return bad_action;
 118         return (enum sync_action) sysfs_match_word(buf, sync_actions);
 119 }
 120
 121 int read_dev_state(int fd)
 122 {
 123         char buf[60];
 124         int n = read_attr(buf, 60, fd);
 125         char *cp;
 126         int rv = 0;
 127
 128         if (n <= 0)
 129                 return 0;
 130
 131         cp = buf;
 132         while (cp) {
 133                 if (sysfs_attr_match(cp, "faulty"))
 134                         rv |= DS_FAULTY;
 135                 if (sysfs_attr_match(cp, "in_sync"))
 136                         rv |= DS_INSYNC;
 137                 if (sysfs_attr_match(cp, "write_mostly"))
 138                         rv |= DS_WRITE_MOSTLY;
 139                 if (sysfs_attr_match(cp, "spare"))
 140                         rv |= DS_SPARE;
 141                 if (sysfs_attr_match(cp, "blocked"))
 142                         rv |= DS_BLOCKED;
 143                 cp = strchr(cp, ',');
 144                 if (cp)
 145                         cp++;
 146         }
 147         return rv;
 148 }
 149
 150 static void signal_manager(void)
 151 {
 152         /* tgkill(getpid(), mon_tid, SIGUSR1); */
 153         int pid = getpid();
 154         syscall(SYS_tgkill, pid, mgr_tid, SIGUSR1);
 155 }
 156
 157 /* Monitor a set of active md arrays - all of which share the
 158  * same metadata - and respond to events that require
 159  * metadata update.
 160  *
 161  * New arrays are detected by another thread which allocates
 162  * required memory and attaches the data structure to our list.
 163  *
 164  * Events:
 165  *  Array stops.
 166  *    This is detected by array_state going to 'clear' or 'inactive'.
 167  *    while we thought it was active.
 168  *    Response is to mark metadata as clean and 'clear' the array(??)
 169  *  write-pending
 170  *    array_state if 'write-pending'
 171  *    We mark metadata as 'dirty' then set array to 'active'.
 172  *  active_idle
 173  *    Either ignore, or mark clean, then mark metadata as clean.
 174  *
 175  *  device fails
 176  *    detected by rd-N/state reporting "faulty"
 177  *    mark device as 'failed' in metadata, let the kernel release the
 178  *    device by writing '-blocked' to rd/state, and finally write 'remove' to
 179  *    rd/state.  Before a disk can be replaced it must be failed and removed
 180  *    from all container members, this will be preemptive for the other
 181  *    arrays... safe?
 182  *
 183  *  sync completes
 184  *    sync_action was 'resync' and becomes 'idle' and resync_start becomes
 185  *    MaxSector
 186  *    Notify metadata that sync is complete.
 187  *
 188  *  recovery completes
 189  *    sync_action changes from 'recover' to 'idle'
 190  *    Check each device state and mark metadata if 'faulty' or 'in_sync'.
 191  *
 192  *  deal with resync
 193  *    This only happens on finding a new array... mdadm will have set
 194  *    'resync_start' to the correct value.  If 'resync_start' indicates that an
 195  *    resync needs to occur set the array to the 'active' state rather than the
 196  *    initial read-auto state.
 197  *
 198  *
 199  *
 200  * We wait for a change (poll/select) on array_state, sync_action, and
 201  * each rd-X/state file.
 202  * When we get any change, we check everything.  So read each state file,
 203  * then decide what to do.
 204  *
 205  * The core action is to write new metadata to all devices in the array.
 206  * This is done at most once on any wakeup.
 207  * After that we might:
 208  *   - update the array_state
 209  *   - set the role of some devices.
 210  *   - request a sync_action
 211  *
 212  */
 213
 214 #define ARRAY_DIRTY 1
 215 #define ARRAY_BUSY 2
 216 static int read_and_act(struct active_array *a)
 217 {
 218         unsigned long long sync_completed;
 219         int check_degraded = 0;
 220         int check_reshape = 0;
 221         int deactivate = 0;
 222         struct mdinfo *mdi;
 223         int ret = 0;
 224         int count = 0;
 225
 226         a->next_state = bad_word;
 227         a->next_action = bad_action;
 228
 229         a->curr_state = read_state(a->info.state_fd);
 230         a->curr_action = read_action(a->action_fd);
 231         a->info.resync_start = read_resync_start(a->resync_start_fd);
 232         sync_completed = read_sync_completed(a->sync_completed_fd);
 233         for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
 234                 mdi->next_state = 0;
 235                 mdi->curr_state = 0;
 236                 if (mdi->state_fd >= 0) {
 237                         mdi->recovery_start = read_resync_start(mdi->recovery_fd);
 238                         mdi->curr_state = read_dev_state(mdi->state_fd);
 239                 }
 240         }
 241
 242         if (a->curr_state > inactive &&
 243             a->prev_state == inactive) {
 244                 /* array has been started
 245                  * possible that container operation has to be completed
 246                  */
 247                 a->container->ss->set_array_state(a, 0);
 248         }
 249         if (a->curr_state <= inactive &&
 250             a->prev_state > inactive) {
 251                 /* array has been stopped */
 252                 a->container->ss->set_array_state(a, 1);
 253                 a->next_state = clear;
 254                 deactivate = 1;
 255         }
 256         if (a->curr_state == write_pending) {
 257                 a->container->ss->set_array_state(a, 0);
 258                 a->next_state = active;
 259                 ret |= ARRAY_DIRTY;
 260         }
 261         if (a->curr_state == active_idle) {
 262                 /* Set array to 'clean' FIRST, then mark clean
 263                  * in the metadata
 264                  */
 265                 a->next_state = clean;
 266                 ret |= ARRAY_DIRTY;
 267         }
 268         if (a->curr_state == clean) {
 269                 a->container->ss->set_array_state(a, 1);
 270         }
 271         if (a->curr_state == active ||
 272             a->curr_state == suspended ||
 273             a->curr_state == bad_word)
 274                 ret |= ARRAY_DIRTY;
 275         if (a->curr_state == readonly) {
 276                 /* Well, I'm ready to handle things.  If readonly
 277                  * wasn't requested, transition to read-auto.
 278                  */
 279                 char buf[64];
 280                 read_attr(buf, sizeof(buf), a->metadata_fd);
 281                 if (strncmp(buf, "external:-", 10) == 0) {
 282                         /* explicit request for readonly array.  Leave it alone */
 283                         ;
 284                 } else {
 285                         if (a->container->ss->set_array_state(a, 2))
 286                                 a->next_state = read_auto; /* array is clean */
 287                         else {
 288                                 a->next_state = active; /* Now active for recovery etc */
 289                                 ret |= ARRAY_DIRTY;
 290                         }
 291                 }
 292         }
 293
 294         if (!deactivate &&
 295             a->curr_action == idle &&
 296             a->prev_action == resync) {
 297                 /* A resync has finished.  The endpoint is recorded in
 298                  * 'sync_start'.  We don't update the metadata
 299                  * until the array goes inactive or readonly though.
 300                  * Just check if we need to fiddle spares.
 301                  */
 302                 a->container->ss->set_array_state(a, a->curr_state <= clean);
 303                 check_degraded = 1;
 304         }
 305
 306         if (!deactivate &&
 307             a->curr_action == idle &&
 308             a->prev_action == recover) {
 309                 /* A recovery has finished.  Some disks may be in sync now,
 310                  * and the array may no longer be degraded
 311                  */
 312                 for (mdi = a->info.devs ; mdi ; mdi = mdi->next) {
 313                         a->container->ss->set_disk(a, mdi->disk.raid_disk,
 314                                                    mdi->curr_state);
 315                         if (! (mdi->curr_state & DS_INSYNC))
 316                                 check_degraded = 1;
 317                         count++;
 318                 }
 319                 if (count != a->info.array.raid_disks)
 320                         check_degraded = 1;
 321         }
 322
 323         if (!deactivate &&
 324             a->curr_action == reshape &&
 325             a->prev_action != reshape)
 326                 /* reshape was requested by mdadm.  Need to see if
 327                  * new devices have been added.  Manager does that
 328                  * when it sees check_reshape
 329                  */
 330                 check_reshape = 1;
 331
 332         /* Check for failures and if found:
 333          * 1/ Record the failure in the metadata and unblock the device.
 334          *    FIXME update the kernel to stop notifying on failed drives when
 335          *    the array is readonly and we have cleared 'blocked'
 336          * 2/ Try to remove the device if the array is writable, or can be
 337          *    made writable.
 338          */
 339         for (mdi = a->info.devs ; mdi ; mdi = mdi->next) {
 340                 if (mdi->curr_state & DS_FAULTY) {
 341                         a->container->ss->set_disk(a, mdi->disk.raid_disk,
 342                                                    mdi->curr_state);
 343                         check_degraded = 1;
 344                         if (mdi->curr_state & DS_BLOCKED)
 345                                 mdi->next_state |= DS_UNBLOCK;
 346                         if (a->curr_state == read_auto) {
 347                                 a->container->ss->set_array_state(a, 0);
 348                                 a->next_state = active;
 349                         }
 350                         if (a->curr_state > readonly)
 351                                 mdi->next_state |= DS_REMOVE;
 352                 }
 353         }
 354
 355         /* Check for recovery checkpoint notifications.  We need to be a
 356          * minimum distance away from the last checkpoint to prevent
 357          * over checkpointing.  Note reshape checkpointing is handled
 358          * in the second branch.
 359          */
 360         if (sync_completed > a->last_checkpoint &&
 361             sync_completed - a->last_checkpoint > a->info.component_size >> 4 &&
 362             a->curr_action > reshape) {
 363                 /* A (non-reshape) sync_action has reached a checkpoint.
 364                  * Record the updated position in the metadata
 365                  */
 366                 a->last_checkpoint = sync_completed;
 367                 a->container->ss->set_array_state(a, a->curr_state <= clean);
 368         } else if ((a->curr_action == idle && a->prev_action == reshape) ||
 369                    (a->curr_action == reshape
 370                     && sync_completed > a->last_checkpoint) ) {
 371                 /* Reshape has progressed or completed so we need to
 372                  * update the array state - and possibly the array size
 373                  */
 374                 if (sync_completed != 0)
 375                         a->last_checkpoint = sync_completed;
 376                 /* We might need to update last_checkpoint depending on
 377                  * the reason that reshape finished.
 378                  * if array reshape is really finished:
 379                  *        set check point to the end, this allows
 380                  *        set_array_state() to finalize reshape in metadata
 381                  * if reshape if broken: do not set checkpoint to the end
 382                  *        this allows for reshape restart from checkpoint
 383                  */
 384                 if ((a->curr_action != reshape) &&
 385                     (a->prev_action == reshape)) {
 386                         char buf[40];
 387                         if ((sysfs_get_str(&a->info, NULL,
 388                                           "reshape_position",
 389                                           buf,
 390                                           sizeof(buf)) >= 0) &&
 391                              strncmp(buf, "none", 4) == 0)
 392                                 a->last_checkpoint = a->info.component_size;
 393                 }
 394                 a->container->ss->set_array_state(a, a->curr_state <= clean);
 395                 a->last_checkpoint = sync_completed;
 396         }
 397
 398         if (sync_completed > a->last_checkpoint)
 399                 a->last_checkpoint = sync_completed;
 400
 401         a->container->ss->sync_metadata(a->container);
 402         dprintf("%s(%d): state:%s action:%s next(", __func__, a->info.container_member,
 403                 array_states[a->curr_state], sync_actions[a->curr_action]);
 404
 405         /* Effect state changes in the array */
 406         if (a->next_state != bad_word) {
 407                 dprintf(" state:%s", array_states[a->next_state]);
 408                 write_attr(array_states[a->next_state], a->info.state_fd);
 409         }
 410         if (a->next_action != bad_action) {
 411                 write_attr(sync_actions[a->next_action], a->action_fd);
 412                 dprintf(" action:%s", sync_actions[a->next_action]);
 413         }
 414         for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
 415                 if (mdi->next_state & DS_UNBLOCK) {
 416                         dprintf(" %d:-blocked", mdi->disk.raid_disk);
 417                         write_attr("-blocked", mdi->state_fd);
 418                 }
 419
 420                 if ((mdi->next_state & DS_REMOVE) && mdi->state_fd >= 0) {
 421                         int remove_result;
 422
 423                         /* The kernel may not be able to immediately remove the
 424                          * disk.  In that case we wait a little while and
 425                          * try again.
 426                          */
 427                         remove_result = write_attr("remove", mdi->state_fd);
 428                         if (remove_result > 0) {
 429                                 dprintf(" %d:removed", mdi->disk.raid_disk);
 430                                 close(mdi->state_fd);
 431                                 close(mdi->recovery_fd);
 432                                 mdi->state_fd = -1;
 433                         } else
 434                                 ret |= ARRAY_BUSY;
 435                 }
 436                 if (mdi->next_state & DS_INSYNC) {
 437                         write_attr("+in_sync", mdi->state_fd);
 438                         dprintf(" %d:+in_sync", mdi->disk.raid_disk);
 439                 }
 440         }
 441         dprintf(" )\n");
 442
 443         /* move curr_ to prev_ */
 444         a->prev_state = a->curr_state;
 445
 446         a->prev_action = a->curr_action;
 447
 448         for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
 449                 mdi->prev_state = mdi->curr_state;
 450                 mdi->next_state = 0;
 451         }
 452
 453         if (check_degraded || check_reshape) {
 454                 /* manager will do the actual check */
 455                 if (check_degraded)
 456                         a->check_degraded = 1;
 457                 if (check_reshape)
 458                         a->check_reshape = 1;
 459                 signal_manager();
 460         }
 461
 462         if (deactivate)
 463                 a->container = NULL;
 464
 465         return ret;
 466 }
 467
 468 static struct mdinfo *
 469 find_device(struct active_array *a, int major, int minor)
 470 {
 471         struct mdinfo *mdi;
 472
 473         for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
 474                 if (mdi->disk.major == major && mdi->disk.minor == minor)
 475                         return mdi;
 476
 477         return NULL;
 478 }
 479
 480 static void reconcile_failed(struct active_array *aa, struct mdinfo *failed)
 481 {
 482         struct active_array *a;
 483         struct mdinfo *victim;
 484
 485         for (a = aa; a; a = a->next) {
 486                 if (!a->container || a->to_remove)
 487                         continue;
 488                 victim = find_device(a, failed->disk.major, failed->disk.minor);
 489                 if (!victim)
 490                         continue;
 491
 492                 if (!(victim->curr_state & DS_FAULTY))
 493                         write_attr("faulty", victim->state_fd);
 494         }
 495 }
 496
 497 #ifdef DEBUG
 498 static void dprint_wake_reasons(fd_set *fds)
 499 {
 500         int i;
 501         char proc_path[256];
 502         char link[256];
 503         char *basename;
 504         int rv;
 505
 506         fprintf(stderr, "monitor: wake ( ");
 507         for (i = 0; i < FD_SETSIZE; i++) {
 508                 if (FD_ISSET(i, fds)) {
 509                         sprintf(proc_path, "/proc/%d/fd/%d",
 510                                 (int) getpid(), i);
 511
 512                         rv = readlink(proc_path, link, sizeof(link) - 1);
 513                         if (rv < 0) {
 514                                 fprintf(stderr, "%d:unknown ", i);
 515                                 continue;
 516                         }
 517                         link[rv] = '\0';
 518                         basename = strrchr(link, '/');
 519                         fprintf(stderr, "%d:%s ",
 520                                 i, basename ? ++basename : link);
 521                 }
 522         }
 523         fprintf(stderr, ")\n");
 524 }
 525 #endif
 526
 527 int monitor_loop_cnt;
 528
 529 static int wait_and_act(struct supertype *container, int nowait)
 530 {
 531         fd_set rfds;
 532         int maxfd = 0;
 533         struct active_array **aap = &container->arrays;
 534         struct active_array *a, **ap;
 535         int rv;
 536         struct mdinfo *mdi;
 537         static unsigned int dirty_arrays = ~0; /* start at some non-zero value */
 538
 539         FD_ZERO(&rfds);
 540
 541         for (ap = aap ; *ap ;) {
 542                 a = *ap;
 543                 /* once an array has been deactivated we want to
 544                  * ask the manager to discard it.
 545                  */
 546                 if (!a->container || a->to_remove) {
 547                         if (discard_this) {
 548                                 ap = &(*ap)->next;
 549                                 continue;
 550                         }
 551                         *ap = a->next;
 552                         a->next = NULL;
 553                         discard_this = a;
 554                         signal_manager();
 555                         continue;
 556                 }
 557
 558                 add_fd(&rfds, &maxfd, a->info.state_fd);
 559                 add_fd(&rfds, &maxfd, a->action_fd);
 560                 add_fd(&rfds, &maxfd, a->sync_completed_fd);
 561                 for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
 562                         add_fd(&rfds, &maxfd, mdi->state_fd);
 563
 564                 ap = &(*ap)->next;
 565         }
 566
 567         if (manager_ready && (*aap == NULL || (sigterm && !dirty_arrays))) {
 568                 /* No interesting arrays, or we have been told to
 569                  * terminate and everything is clean.  Lets see about
 570                  * exiting.  Note that blocking at this point is not a
 571                  * problem as there are no active arrays, there is
 572                  * nothing that we need to be ready to do.
 573                  */
 574                 int fd;
 575                 if (sigterm)
 576                         fd = open_dev_excl(container->devnm);
 577                 else
 578                         fd = open_dev_flags(container->devnm, O_RDONLY|O_EXCL);
 579                 if (fd >= 0 || errno != EBUSY) {
 580                         /* OK, we are safe to leave */
 581                         if (sigterm && !dirty_arrays)
 582                                 dprintf("caught sigterm, all clean... exiting\n");
 583                         else
 584                                 dprintf("no arrays to monitor... exiting\n");
 585                         if (!sigterm)
 586                                 /* On SIGTERM, someone (the take-over mdmon) will
 587                                  * clean up
 588                                  */
 589                                 remove_pidfile(container->devnm);
 590                         exit_now = 1;
 591                         signal_manager();
 592                         close(fd);
 593                         exit(0);
 594                 }
 595         }
 596
 597         if (!nowait) {
 598                 sigset_t set;
 599                 struct timespec ts;
 600                 ts.tv_sec = 24*3600;
 601                 ts.tv_nsec = 0;
 602                 if (*aap == NULL || container->retry_soon) {
 603                         /* just waiting to get O_EXCL access */
 604                         ts.tv_sec = 0;
 605                         ts.tv_nsec = 20000000ULL;
 606                 }
 607                 sigprocmask(SIG_UNBLOCK, NULL, &set);
 608                 sigdelset(&set, SIGUSR1);
 609                 monitor_loop_cnt |= 1;
 610                 rv = pselect(maxfd+1, NULL, NULL, &rfds, &ts, &set);
 611                 monitor_loop_cnt += 1;
 612                 if (rv == -1 && errno == EINTR)
 613                         rv = 0;
 614                 #ifdef DEBUG
 615                 dprint_wake_reasons(&rfds);
 616                 #endif
 617                 container->retry_soon = 0;
 618         }
 619
 620         if (update_queue) {
 621                 struct metadata_update *this;
 622
 623                 for (this = update_queue; this ; this = this->next)
 624                         container->ss->process_update(container, this);
 625
 626                 update_queue_handled = update_queue;
 627                 update_queue = NULL;
 628                 signal_manager();
 629                 container->ss->sync_metadata(container);
 630         }
 631
 632         rv = 0;
 633         dirty_arrays = 0;
 634         for (a = *aap; a ; a = a->next) {
 635
 636                 if (a->replaces && !discard_this) {
 637                         struct active_array **ap;
 638                         for (ap = &a->next; *ap && *ap != a->replaces;
 639                              ap = & (*ap)->next)
 640                                 ;
 641                         if (*ap)
 642                                 *ap = (*ap)->next;
 643                         discard_this = a->replaces;
 644                         a->replaces = NULL;
 645                         /* FIXME check if device->state_fd need to be cleared?*/
 646                         signal_manager();
 647                 }
 648                 if (a->container && !a->to_remove) {
 649                         int ret = read_and_act(a);
 650                         rv |= 1;
 651                         dirty_arrays += !!(ret & ARRAY_DIRTY);
 652                         /* when terminating stop manipulating the array after it
 653                          * is clean, but make sure read_and_act() is given a
 654                          * chance to handle 'active_idle'
 655                          */
 656                         if (sigterm && !(ret & ARRAY_DIRTY))
 657                                 a->container = NULL; /* stop touching this array */
 658                         if (ret & ARRAY_BUSY)
 659                                 container->retry_soon = 1;
 660                 }
 661         }
 662
 663         /* propagate failures across container members */
 664         for (a = *aap; a ; a = a->next) {
 665                 if (!a->container || a->to_remove)
 666                         continue;
 667                 for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
 668                         if (mdi->curr_state & DS_FAULTY)
 669                                 reconcile_failed(*aap, mdi);
 670         }
 671
 672         return rv;
 673 }
 674
 675 void do_monitor(struct supertype *container)
 676 {
 677         int rv;
 678         int first = 1;
 679         do {
 680                 rv = wait_and_act(container, first);
 681                 first = 0;
 682         } while (rv >= 0);
 683 }