mdmon.c

   1 /*
   2  * mdmon - monitor external metadata arrays
   3  *
   4  * Copyright (C) 2007-2008 Neil Brown <neilb@suse.de>
   5  * Copyright (C) 2007-2008 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
 117 int make_pidfile(char *devname, int o_excl)
 118 {
 119         char path[100];
 120         char pid[10];
 121         int fd;
 122         int n;
 123
 124         if (sigterm)
 125                 return -1;
 126
 127         sprintf(path, "/var/run/mdadm/%s.pid", devname);
 128
 129         fd = open(path, O_RDWR|O_CREAT|o_excl, 0600);
 130         if (fd < 0)
 131                 return -errno;
 132         sprintf(pid, "%d\n", getpid());
 133         n = write(fd, pid, strlen(pid));
 134         close(fd);
 135         if (n < 0)
 136                 return -errno;
 137         return 0;
 138 }
 139
 140 int is_container_member(struct mdstat_ent *mdstat, char *container)
 141 {
 142         if (mdstat->metadata_version == NULL ||
 143             strncmp(mdstat->metadata_version, "external:", 9) != 0 ||
 144             !is_subarray(mdstat->metadata_version+9) ||
 145             strncmp(mdstat->metadata_version+10, container, strlen(container)) != 0 ||
 146             mdstat->metadata_version[10+strlen(container)] != '/')
 147                 return 0;
 148
 149         return 1;
 150 }
 151
 152 void remove_pidfile(char *devname);
 153 static void try_kill_monitor(char *devname)
 154 {
 155         char buf[100];
 156         int fd;
 157         pid_t pid;
 158         struct mdstat_ent *mdstat;
 159
 160         sprintf(buf, "/var/run/mdadm/%s.pid", devname);
 161         fd = open(buf, O_RDONLY);
 162         if (fd < 0)
 163                 return;
 164
 165         if (read(fd, buf, sizeof(buf)) < 0) {
 166                 close(fd);
 167                 return;
 168         }
 169
 170         close(fd);
 171         pid = strtoul(buf, NULL, 10);
 172
 173         /* first rule of survival... don't off yourself */
 174         if (pid == getpid())
 175                 return;
 176
 177         /* kill this process if it is mdmon */
 178         sprintf(buf, "/proc/%lu/cmdline", (unsigned long) pid);
 179         fd = open(buf, O_RDONLY);
 180         if (fd < 0)
 181                 return;
 182
 183         if (read(fd, buf, sizeof(buf)) < 0) {
 184                 close(fd);
 185                 return;
 186         }
 187
 188         if (!strstr(buf, "mdmon"))
 189                 return;
 190
 191         kill(pid, SIGTERM);
 192
 193         mdstat = mdstat_read(0, 0);
 194         for ( ; mdstat; mdstat = mdstat->next)
 195                 if (is_container_member(mdstat, devname)) {
 196                         sprintf(buf, "/dev/%s", mdstat->dev);
 197                         WaitClean(buf, 0);
 198                 }
 199         free_mdstat(mdstat);
 200         remove_pidfile(devname);
 201 }
 202
 203 void remove_pidfile(char *devname)
 204 {
 205         char buf[100];
 206
 207         if (sigterm)
 208                 return;
 209
 210         sprintf(buf, "/var/run/mdadm/%s.pid", devname);
 211         unlink(buf);
 212         sprintf(buf, "/var/run/mdadm/%s.sock", devname);
 213         unlink(buf);
 214 }
 215
 216 int make_control_sock(char *devname)
 217 {
 218         char path[100];
 219         int sfd;
 220         long fl;
 221         struct sockaddr_un addr;
 222
 223         if (sigterm)
 224                 return -1;
 225
 226         sprintf(path, "/var/run/mdadm/%s.sock", devname);
 227         unlink(path);
 228         sfd = socket(PF_LOCAL, SOCK_STREAM, 0);
 229         if (sfd < 0)
 230                 return -1;
 231
 232         addr.sun_family = PF_LOCAL;
 233         strcpy(addr.sun_path, path);
 234         if (bind(sfd, &addr, sizeof(addr)) < 0) {
 235                 close(sfd);
 236                 return -1;
 237         }
 238         listen(sfd, 10);
 239         fl = fcntl(sfd, F_GETFL, 0);
 240         fl |= O_NONBLOCK;
 241         fcntl(sfd, F_SETFL, fl);
 242         return sfd;
 243 }
 244
 245 int socket_hup_requested;
 246 static void hup(int sig)
 247 {
 248         socket_hup_requested = 1;
 249 }
 250
 251 static void term(int sig)
 252 {
 253         sigterm = 1;
 254 }
 255
 256 static void wake_me(int sig)
 257 {
 258
 259 }
 260
 261 /* if we are debugging and starting mdmon by hand then don't fork */
 262 static int do_fork(void)
 263 {
 264         #ifdef DEBUG
 265         if (check_env("MDADM_NO_MDMON"))
 266                 return 0;
 267         #endif
 268
 269         return 1;
 270 }
 271
 272 void usage(void)
 273 {
 274         fprintf(stderr, "Usage: mdmon [--switch-root dir] /device/name/for/container\n");
 275         exit(2);
 276 }
 277
 278 int main(int argc, char *argv[])
 279 {
 280         int mdfd;
 281         struct mdinfo *mdi, *di;
 282         struct supertype *container;
 283         sigset_t set;
 284         struct sigaction act;
 285         int pfd[2];
 286         int status;
 287         int ignore;
 288         char *container_name = NULL;
 289         char *switchroot = NULL;
 290         int devnum;
 291         char *devname;
 292
 293         switch (argc) {
 294         case 2:
 295                 container_name = argv[1];
 296                 break;
 297         case 4:
 298                 if (strcmp(argv[1], "--switch-root") != 0) {
 299                         fprintf(stderr, "mdmon: unknown argument %s\n", argv[1]);
 300                         usage();
 301                 }
 302                 switchroot = argv[2];
 303                 container_name = argv[3];
 304                 break;
 305         default:
 306                 usage();
 307         }
 308
 309         devnum = devname2devnum(container_name);
 310         devname = devnum2devname(devnum);
 311         if (strcmp(container_name, devname) != 0) {
 312                 fprintf(stderr, "mdmon: %s is not a valid md device name\n",
 313                         container_name);
 314                 exit(1);
 315         }
 316         mdfd = open_dev(devnum);
 317         if (mdfd < 0) {
 318                 fprintf(stderr, "mdmon: %s: %s\n", container_name,
 319                         strerror(errno));
 320                 exit(1);
 321         }
 322         if (md_get_version(mdfd) < 0) {
 323                 fprintf(stderr, "mdmon: %s: Not an md device\n",
 324                         container_name);
 325                 exit(1);
 326         }
 327
 328         /* Fork, and have the child tell us when they are ready */
 329         if (do_fork()) {
 330                 if (pipe(pfd) != 0) {
 331                         fprintf(stderr, "mdmon: failed to create pipe\n");
 332                         exit(1);
 333                 }
 334                 switch(fork()) {
 335                 case -1:
 336                         fprintf(stderr, "mdmon: failed to fork: %s\n",
 337                                 strerror(errno));
 338                         exit(1);
 339                 case 0: /* child */
 340                         close(pfd[0]);
 341                         break;
 342                 default: /* parent */
 343                         close(pfd[1]);
 344                         if (read(pfd[0], &status, sizeof(status)) != sizeof(status)) {
 345                                 wait(&status);
 346                                 status = WEXITSTATUS(status);
 347                         }
 348                         exit(status);
 349                 }
 350         } else
 351                 pfd[0] = pfd[1] = -1;
 352
 353         container = malloc(sizeof(*container));
 354         container->devnum = devnum;
 355         container->devname = devname;
 356         container->arrays = NULL;
 357         container->subarray[0] = 0;
 358
 359         if (!container->devname) {
 360                 fprintf(stderr, "mdmon: failed to allocate container name string\n");
 361                 exit(3);
 362         }
 363
 364         mdi = sysfs_read(mdfd, container->devnum,
 365                          GET_VERSION|GET_LEVEL|GET_DEVS);
 366
 367         if (!mdi) {
 368                 fprintf(stderr, "mdmon: failed to load sysfs info for %s\n",
 369                         container->devname);
 370                 exit(3);
 371         }
 372         if (mdi->array.level != UnSet) {
 373                 fprintf(stderr, "mdmon: %s is not a container - cannot monitor\n",
 374                         container_name);
 375                 exit(3);
 376         }
 377         if (mdi->array.major_version != -1 ||
 378             mdi->array.minor_version != -2) {
 379                 fprintf(stderr, "mdmon: %s does not use external metadata - cannot monitor\n",
 380                         container_name);
 381                 exit(3);
 382         }
 383
 384         container->ss = find_metadata_methods(mdi->text_version);
 385         if (container->ss == NULL) {
 386                 fprintf(stderr, "mdmon: %s uses unknown metadata: %s\n",
 387                         container_name, mdi->text_version);
 388                 exit(3);
 389         }
 390
 391         container->devs = NULL;
 392         for (di = mdi->devs; di; di = di->next) {
 393                 struct mdinfo *cd = malloc(sizeof(*cd));
 394                 *cd = *di;
 395                 cd->next = container->devs;
 396                 container->devs = cd;
 397         }
 398         sysfs_free(mdi);
 399
 400         /* SIGUSR is sent between parent and child.  So both block it
 401          * and enable it only with pselect.
 402          */
 403         sigemptyset(&set);
 404         sigaddset(&set, SIGUSR1);
 405         sigaddset(&set, SIGHUP);
 406         sigaddset(&set, SIGALRM);
 407         sigaddset(&set, SIGTERM);
 408         sigprocmask(SIG_BLOCK, &set, NULL);
 409         act.sa_handler = wake_me;
 410         act.sa_flags = 0;
 411         sigaction(SIGUSR1, &act, NULL);
 412         sigaction(SIGALRM, &act, NULL);
 413         act.sa_handler = hup;
 414         sigaction(SIGHUP, &act, NULL);
 415         act.sa_handler = term;
 416         sigaction(SIGTERM, &act, NULL);
 417         act.sa_handler = SIG_IGN;
 418         sigaction(SIGPIPE, &act, NULL);
 419
 420         if (switchroot) {
 421                 /* we assume we assume that /sys /proc /dev are available in
 422                  * the new root (see nash:setuproot)
 423                  *
 424                  * kill any monitors in the current namespace and change
 425                  * to the new one
 426                  */
 427                 try_kill_monitor(container->devname);
 428                 if (chroot(switchroot) != 0) {
 429                         fprintf(stderr, "mdmon: failed to chroot to '%s': %s\n",
 430                                 switchroot, strerror(errno));
 431                         exit(4);
 432                 }
 433         }
 434
 435         /* If this fails, we hope it already exists
 436          * pid file lives in /var/run/mdadm/mdXX.pid
 437          */
 438         mkdir("/var", 0600);
 439         mkdir("/var/run", 0600);
 440         mkdir("/var/run/mdadm", 0600);
 441         ignore = chdir("/");
 442         if (make_pidfile(container->devname, O_EXCL) < 0) {
 443                 if (ping_monitor(container->devname) == 0) {
 444                         fprintf(stderr, "mdmon: %s already managed\n",
 445                                 container->devname);
 446                         exit(3);
 447                 } else {
 448                         int err;
 449
 450                         /* cleanup the old monitor, this one is taking over */
 451                         try_kill_monitor(container->devname);
 452                         err = make_pidfile(container->devname, 0);
 453                         if (err < 0) {
 454                                 fprintf(stderr, "mdmon: %s Cannot create pidfile\n",
 455                                         container->devname);
 456                                 if (err == -EROFS) {
 457                                         /* FIXME implement a mechanism to
 458                                          * prevent duplicate monitor instances
 459                                          */
 460                                         fprintf(stderr,
 461                                                 "mdmon: continuing on read-only file system\n");
 462                                 } else
 463                                         exit(3);
 464                         }
 465                 }
 466         }
 467         container->sock = make_control_sock(container->devname);
 468
 469         if (container->ss->load_super(container, mdfd, container_name)) {
 470                 fprintf(stderr, "mdmon: Cannot load metadata for %s\n",
 471                         container_name);
 472                 exit(3);
 473         }
 474         close(mdfd);
 475
 476         /* Ok, this is close enough.  We can say goodbye to our parent now.
 477          */
 478         status = 0;
 479         if (write(pfd[1], &status, sizeof(status)) < 0)
 480                 fprintf(stderr, "mdmon: failed to notify our parent: %d\n",
 481                         getppid());
 482         close(pfd[1]);
 483
 484         setsid();
 485         close(0);
 486         open("/dev/null", O_RDWR);
 487         close(1);
 488         ignore = dup(0);
 489 #ifndef DEBUG
 490         close(2);
 491         ignore = dup(0);
 492 #endif
 493
 494         mlockall(MCL_FUTURE);
 495
 496         if (clone_monitor(container) < 0) {
 497                 fprintf(stderr, "mdmon: failed to start monitor process: %s\n",
 498                         strerror(errno));
 499                 exit(2);
 500         }
 501
 502         do_manager(container);
 503
 504         exit(0);
 505 }