mdmon.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 /*
  22  * md array manager.
  23  * When md arrays have user-space managed metadata, this is the program
  24  * that does the managing.
  25  *
  26  * Given one argument: the name of the array (e.g. /dev/md0) that is
  27  * the container.
  28  * We fork off a helper that runs high priority and mlocked.  It responds to
  29  * device failures and other events that might stop writeout, or that are
  30  * trivial to deal with.
  31  * The main thread then watches for new arrays being created in the container
  32  * and starts monitoring them too ... along with a few other tasks.
  33  *
  34  * The main thread communicates with the priority thread by writing over
  35  * a pipe.
  36  * Separate programs can communicate with the main thread via Unix-domain
  37  * socket.
  38  * The two threads share address space and open file table.
  39  *
  40  */
  41
  42 #ifndef _GNU_SOURCE
  43 #define _GNU_SOURCE
  44 #endif
  45
  46 #include        <unistd.h>
  47 #include        <stdlib.h>
  48 #include        <sys/types.h>
  49 #include        <sys/stat.h>
  50 #include        <sys/socket.h>
  51 #include        <sys/un.h>
  52 #include        <sys/mman.h>
  53 #include        <sys/syscall.h>
  54 #include        <sys/wait.h>
  55 #include        <stdio.h>
  56 #include        <errno.h>
  57 #include        <string.h>
  58 #include        <fcntl.h>
  59 #include        <signal.h>
  60 #include        <dirent.h>
  61
  62 #include        <sched.h>
  63
  64 #include        "mdadm.h"
  65 #include        "mdmon.h"
  66
  67 struct active_array *discard_this;
  68 struct active_array *pending_discard;
  69
  70 int mon_tid, mgr_tid;
  71
  72 int sigterm;
  73
  74 int run_child(void *v)
  75 {
  76         struct supertype *c = v;
  77
  78         do_monitor(c);
  79         return 0;
  80 }
  81
  82 #ifdef __ia64__
  83 int __clone2(int (*fn)(void *),
  84             void *child_stack_base, size_t stack_size,
  85             int flags, void *arg, ...
  86          /* pid_t *pid, struct user_desc *tls, pid_t *ctid */ );
  87 #endif
  88  int clone_monitor(struct supertype *container)
  89 {
  90         static char stack[4096];
  91
  92 #ifdef __ia64__
  93         mon_tid = __clone2(run_child, stack, sizeof(stack),
  94                    CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD,
  95                    container);
  96 #else
  97         mon_tid = clone(run_child, stack+4096-64,
  98                    CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD,
  99                    container);
 100 #endif
 101
 102         mgr_tid = syscall(SYS_gettid);
 103
 104         return mon_tid;
 105 }
 106
 107 static struct superswitch *find_metadata_methods(char *vers)
 108 {
 109         if (strcmp(vers, "ddf") == 0)
 110                 return &super_ddf;
 111         if (strcmp(vers, "imsm") == 0)
 112                 return &super_imsm;
 113         return NULL;
 114 }
 115
 116 int make_pidfile(char *devname, int o_excl)
 117 {
 118         char path[100];
 119         char pid[10];
 120         int fd;
 121         int n;
 122
 123         if (sigterm)
 124                 return -1;
 125
 126         sprintf(path, "/var/run/mdadm/%s.pid", devname);
 127
 128         fd = open(path, O_RDWR|O_CREAT|o_excl, 0600);
 129         if (fd < 0)
 130                 return -errno;
 131         sprintf(pid, "%d\n", getpid());
 132         n = write(fd, pid, strlen(pid));
 133         close(fd);
 134         if (n < 0)
 135                 return -errno;
 136         return 0;
 137 }
 138
 139 int is_container_member(struct mdstat_ent *mdstat, char *container)
 140 {
 141         if (mdstat->metadata_version == NULL ||
 142             strncmp(mdstat->metadata_version, "external:", 9) != 0 ||
 143             !is_subarray(mdstat->metadata_version+9) ||
 144             strncmp(mdstat->metadata_version+10, container, strlen(container)) != 0 ||
 145             mdstat->metadata_version[10+strlen(container)] != '/')
 146                 return 0;
 147
 148         return 1;
 149 }
 150
 151 static void try_kill_monitor(pid_t pid, char *devname, int sock)
 152 {
 153         char buf[100];
 154         int fd;
 155         int n;
 156         long fl;
 157
 158         /* first rule of survival... don't off yourself */
 159         if (pid == getpid())
 160                 return;
 161
 162         /* kill this process if it is mdmon */
 163         sprintf(buf, "/proc/%lu/cmdline", (unsigned long) pid);
 164         fd = open(buf, O_RDONLY);
 165         if (fd < 0)
 166                 return;
 167
 168         n = read(fd, buf, sizeof(buf)-1);
 169         buf[sizeof(buf)-1] = 0;
 170         close(fd);
 171
 172         if (n < 0 || !strstr(buf, "mdmon"))
 173                 return;
 174
 175         kill(pid, SIGTERM);
 176
 177         /* Wait for monitor to exit by reading from the socket, after
 178          * clearing the non-blocking flag */
 179         fl = fcntl(sock, F_GETFL, 0);
 180         fl &= ~O_NONBLOCK;
 181         fcntl(sock, F_SETFL, fl);
 182         read(sock, buf, 100);
 183 }
 184
 185 void remove_pidfile(char *devname)
 186 {
 187         char buf[100];
 188
 189         if (sigterm)
 190                 return;
 191
 192         sprintf(buf, "/var/run/mdadm/%s.pid", devname);
 193         unlink(buf);
 194         sprintf(buf, "/var/run/mdadm/%s.sock", devname);
 195         unlink(buf);
 196 }
 197
 198 int make_control_sock(char *devname)
 199 {
 200         char path[100];
 201         int sfd;
 202         long fl;
 203         struct sockaddr_un addr;
 204
 205         if (sigterm)
 206                 return -1;
 207
 208         sprintf(path, "/var/run/mdadm/%s.sock", devname);
 209         unlink(path);
 210         sfd = socket(PF_LOCAL, SOCK_STREAM, 0);
 211         if (sfd < 0)
 212                 return -1;
 213
 214         addr.sun_family = PF_LOCAL;
 215         strcpy(addr.sun_path, path);
 216         if (bind(sfd, &addr, sizeof(addr)) < 0) {
 217                 close(sfd);
 218                 return -1;
 219         }
 220         listen(sfd, 10);
 221         fl = fcntl(sfd, F_GETFL, 0);
 222         fl |= O_NONBLOCK;
 223         fcntl(sfd, F_SETFL, fl);
 224         return sfd;
 225 }
 226
 227 int socket_hup_requested;
 228 static void hup(int sig)
 229 {
 230         socket_hup_requested = 1;
 231 }
 232
 233 static void term(int sig)
 234 {
 235         sigterm = 1;
 236 }
 237
 238 static void wake_me(int sig)
 239 {
 240
 241 }
 242
 243 /* if we are debugging and starting mdmon by hand then don't fork */
 244 static int do_fork(void)
 245 {
 246         #ifdef DEBUG
 247         if (check_env("MDADM_NO_MDMON"))
 248                 return 0;
 249         #endif
 250
 251         return 1;
 252 }
 253
 254 void usage(void)
 255 {
 256         fprintf(stderr, "Usage: mdmon /device/name/for/container [target_dir]\n");
 257         exit(2);
 258 }
 259
 260 static int mdmon(char *devname, int devnum, int must_fork, char *switchroot);
 261
 262 int main(int argc, char *argv[])
 263 {
 264         char *container_name = NULL;
 265         char *switchroot = NULL;
 266         int devnum;
 267         char *devname;
 268         int status = 0;
 269
 270         switch (argc) {
 271         case 3:
 272                 switchroot = argv[2];
 273         case 2:
 274                 container_name = argv[1];
 275                 break;
 276         default:
 277                 usage();
 278         }
 279
 280         if (strcmp(container_name, "/proc/mdstat") == 0) {
 281                 struct mdstat_ent *mdstat, *e;
 282
 283                 /* launch an mdmon instance for each container found */
 284                 mdstat = mdstat_read(0, 0);
 285                 for (e = mdstat; e; e = e->next) {
 286                         if (strncmp(e->metadata_version, "external:", 9) == 0 &&
 287                             !is_subarray(&e->metadata_version[9])) {
 288                                 devname = devnum2devname(e->devnum);
 289                                 /* update cmdline so this mdmon instance can be
 290                                  * distinguished from others in a call to ps(1)
 291                                  */
 292                                 if (strlen(devname) <= strlen(container_name)) {
 293                                         memset(container_name, 0, strlen(container_name));
 294                                         sprintf(container_name, "%s", devname);
 295                                 }
 296                                 status |= mdmon(devname, e->devnum, 1,
 297                                                 switchroot);
 298                         }
 299                 }
 300                 free_mdstat(mdstat);
 301
 302                 return status;
 303         } else if (strncmp(container_name, "md", 2) == 0) {
 304                 devnum = devname2devnum(container_name);
 305                 devname = devnum2devname(devnum);
 306                 if (strcmp(container_name, devname) != 0)
 307                         devname = NULL;
 308         } else {
 309                 struct stat st;
 310
 311                 devnum = NoMdDev;
 312                 if (stat(container_name, &st) == 0)
 313                         devnum = stat2devnum(&st);
 314                 if (devnum == NoMdDev)
 315                         devname = NULL;
 316                 else
 317                         devname = devnum2devname(devnum);
 318         }
 319
 320         if (!devname) {
 321                 fprintf(stderr, "mdmon: %s is not a valid md device name\n",
 322                         container_name);
 323                 exit(1);
 324         }
 325         return mdmon(devname, devnum, do_fork(), switchroot);
 326 }
 327
 328 static int mdmon(char *devname, int devnum, int must_fork, char *switchroot)
 329 {
 330         int mdfd;
 331         struct mdinfo *mdi, *di;
 332         struct supertype *container;
 333         sigset_t set;
 334         struct sigaction act;
 335         int pfd[2];
 336         int status;
 337         int ignore;
 338         pid_t victim = -1;
 339         int victim_sock = -1;
 340
 341         dprintf("starting mdmon for %s in %s\n",
 342                 devname, switchroot ? : "/");
 343
 344         /* switchroot is either a path name starting with '/', or a
 345          * pid of the original mdmon (we have already done the chroot).
 346          * In the latter case, stdin is a socket connected to the original
 347          * mdmon.
 348          */
 349
 350         /* try to spawn mdmon instances from the target file system */
 351         if (switchroot && switchroot[0] == '/' &&
 352             strcmp(switchroot, "/") != 0) {
 353                 pid_t pid;
 354                 char buf[20];
 355
 356                 switch (fork()) {
 357                 case 0:
 358                         victim = mdmon_pid(devnum);
 359                         victim_sock = connect_monitor(devname);
 360                         if (chroot(switchroot) != 0) {
 361                                 fprintf(stderr, "mdmon: failed to chroot to '%s': %s\n",
 362                                         switchroot, strerror(errno));
 363                                 exit(4);
 364                         }
 365                         ignore = chdir("/");
 366                         sprintf(buf, "%d", victim);
 367                         if (victim_sock) {
 368                                 close(0);
 369                                 dup(victim_sock);
 370                                 close(victim_sock);
 371                         }
 372                         execl("/sbin/mdmon", "mdmon", devname, buf, NULL);
 373                         exit(1);
 374                 case -1:
 375                         return 1;
 376                 default:
 377                         pid = wait(&status);
 378                         if (pid > -1 && WIFEXITED(status) &&
 379                             WEXITSTATUS(status) == 0)
 380                                 return 0;
 381                         else
 382                                 return 1;
 383                 }
 384         }
 385
 386         mdfd = open_dev(devnum);
 387         if (mdfd < 0) {
 388                 fprintf(stderr, "mdmon: %s: %s\n", devname,
 389                         strerror(errno));
 390                 return 1;
 391         }
 392         if (md_get_version(mdfd) < 0) {
 393                 fprintf(stderr, "mdmon: %s: Not an md device\n",
 394                         devname);
 395                 return 1;
 396         }
 397
 398         /* Fork, and have the child tell us when they are ready */
 399         if (must_fork) {
 400                 if (pipe(pfd) != 0) {
 401                         fprintf(stderr, "mdmon: failed to create pipe\n");
 402                         return 1;
 403                 }
 404                 switch(fork()) {
 405                 case -1:
 406                         fprintf(stderr, "mdmon: failed to fork: %s\n",
 407                                 strerror(errno));
 408                         return 1;
 409                 case 0: /* child */
 410                         close(pfd[0]);
 411                         break;
 412                 default: /* parent */
 413                         close(pfd[1]);
 414                         if (read(pfd[0], &status, sizeof(status)) != sizeof(status)) {
 415                                 wait(&status);
 416                                 status = WEXITSTATUS(status);
 417                         }
 418                         return status;
 419                 }
 420         } else
 421                 pfd[0] = pfd[1] = -1;
 422
 423         container = calloc(1, sizeof(*container));
 424         container->devnum = devnum;
 425         container->devname = devname;
 426         container->arrays = NULL;
 427         container->subarray[0] = 0;
 428         container->sock = -1;
 429
 430         if (!container->devname) {
 431                 fprintf(stderr, "mdmon: failed to allocate container name string\n");
 432                 exit(3);
 433         }
 434
 435         mdi = sysfs_read(mdfd, container->devnum,
 436                          GET_VERSION|GET_LEVEL|GET_DEVS|SKIP_GONE_DEVS);
 437
 438         if (!mdi) {
 439                 fprintf(stderr, "mdmon: failed to load sysfs info for %s\n",
 440                         container->devname);
 441                 exit(3);
 442         }
 443         if (mdi->array.level != UnSet) {
 444                 fprintf(stderr, "mdmon: %s is not a container - cannot monitor\n",
 445                         devname);
 446                 exit(3);
 447         }
 448         if (mdi->array.major_version != -1 ||
 449             mdi->array.minor_version != -2) {
 450                 fprintf(stderr, "mdmon: %s does not use external metadata - cannot monitor\n",
 451                         devname);
 452                 exit(3);
 453         }
 454
 455         container->ss = find_metadata_methods(mdi->text_version);
 456         if (container->ss == NULL) {
 457                 fprintf(stderr, "mdmon: %s uses unknown metadata: %s\n",
 458                         devname, mdi->text_version);
 459                 exit(3);
 460         }
 461
 462         container->devs = NULL;
 463         for (di = mdi->devs; di; di = di->next) {
 464                 struct mdinfo *cd = malloc(sizeof(*cd));
 465                 *cd = *di;
 466                 cd->next = container->devs;
 467                 container->devs = cd;
 468         }
 469         sysfs_free(mdi);
 470
 471         /* SIGUSR is sent between parent and child.  So both block it
 472          * and enable it only with pselect.
 473          */
 474         sigemptyset(&set);
 475         sigaddset(&set, SIGUSR1);
 476         sigaddset(&set, SIGHUP);
 477         sigaddset(&set, SIGALRM);
 478         sigaddset(&set, SIGTERM);
 479         sigprocmask(SIG_BLOCK, &set, NULL);
 480         act.sa_handler = wake_me;
 481         act.sa_flags = 0;
 482         sigaction(SIGUSR1, &act, NULL);
 483         sigaction(SIGALRM, &act, NULL);
 484         act.sa_handler = hup;
 485         sigaction(SIGHUP, &act, NULL);
 486         act.sa_handler = term;
 487         sigaction(SIGTERM, &act, NULL);
 488         act.sa_handler = SIG_IGN;
 489         sigaction(SIGPIPE, &act, NULL);
 490
 491         if (switchroot) {
 492                 /* we assume we assume that /sys /proc /dev are available in
 493                  * the new root
 494                  */
 495                 if (switchroot[0] == '/') {
 496                         victim = mdmon_pid(container->devnum);
 497                         victim_sock = connect_monitor(container->devname);
 498                 } else {
 499                         victim = atoi(switchroot);
 500                         victim_sock = 0;
 501                 }
 502         }
 503
 504         ignore = chdir("/");
 505         if (victim < 0) {
 506                 if (ping_monitor(container->devname) == 0) {
 507                         fprintf(stderr, "mdmon: %s already managed\n",
 508                                 container->devname);
 509                         exit(3);
 510                 }
 511                 /* if there is a pid file, kill whoever is there just in case */
 512                 victim = mdmon_pid(container->devnum);
 513         }
 514         if (container->ss->load_super(container, mdfd, devname)) {
 515                 fprintf(stderr, "mdmon: Cannot load metadata for %s\n",
 516                         devname);
 517                 exit(3);
 518         }
 519         close(mdfd);
 520
 521         /* Ok, this is close enough.  We can say goodbye to our parent now.
 522          */
 523         status = 0;
 524         if (write(pfd[1], &status, sizeof(status)) < 0)
 525                 fprintf(stderr, "mdmon: failed to notify our parent: %d\n",
 526                         getppid());
 527         close(pfd[1]);
 528
 529         mlockall(MCL_CURRENT | MCL_FUTURE);
 530
 531         if (clone_monitor(container) < 0) {
 532                 fprintf(stderr, "mdmon: failed to start monitor process: %s\n",
 533                         strerror(errno));
 534                 exit(2);
 535         }
 536
 537         if (victim > -1) {
 538                 try_kill_monitor(victim, container->devname, victim_sock);
 539                 close(victim_sock);
 540         }
 541
 542         setsid();
 543         close(0);
 544         open("/dev/null", O_RDWR);
 545         close(1);
 546         ignore = dup(0);
 547 #ifndef DEBUG
 548         close(2);
 549         ignore = dup(0);
 550 #endif
 551
 552         do_manager(container);
 553
 554         exit(0);
 555 }