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 #ifdef USE_PTHREADS
  62 #include        <pthread.h>
  63 #else
  64 #include        <sched.h>
  65 #endif
  66
  67 #include        "mdadm.h"
  68 #include        "mdmon.h"
  69
  70 struct active_array *discard_this;
  71 struct active_array *pending_discard;
  72
  73 int mon_tid, mgr_tid;
  74
  75 int sigterm;
  76
  77 #ifdef USE_PTHREADS
  78 static void *run_child(void *v)
  79 {
  80         struct supertype *c = v;
  81
  82         mon_tid = syscall(SYS_gettid);
  83         do_monitor(c);
  84         return 0;
  85 }
  86
  87 static int clone_monitor(struct supertype *container)
  88 {
  89         pthread_attr_t attr;
  90         pthread_t thread;
  91         int rc;
  92
  93         mon_tid = -1;
  94         pthread_attr_init(&attr);
  95         pthread_attr_setstacksize(&attr, 4096);
  96         pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
  97         rc = pthread_create(&thread, &attr, run_child, container);
  98         if (rc)
  99                 return rc;
 100         while (mon_tid == -1)
 101                 usleep(10);
 102         pthread_attr_destroy(&attr);
 103
 104         mgr_tid = syscall(SYS_gettid);
 105
 106         return mon_tid;
 107 }
 108 #else /* USE_PTHREADS */
 109 static int run_child(void *v)
 110 {
 111         struct supertype *c = v;
 112
 113         do_monitor(c);
 114         return 0;
 115 }
 116
 117 #ifdef __ia64__
 118 int __clone2(int (*fn)(void *),
 119             void *child_stack_base, size_t stack_size,
 120             int flags, void *arg, ...
 121          /* pid_t *pid, struct user_desc *tls, pid_t *ctid */ );
 122 #endif
 123 static int clone_monitor(struct supertype *container)
 124 {
 125         static char stack[4096];
 126
 127 #ifdef __ia64__
 128         mon_tid = __clone2(run_child, stack, sizeof(stack),
 129                    CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD,
 130                    container);
 131 #else
 132         mon_tid = clone(run_child, stack+4096-64,
 133                    CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD,
 134                    container);
 135 #endif
 136
 137         mgr_tid = syscall(SYS_gettid);
 138
 139         return mon_tid;
 140 }
 141 #endif /* USE_PTHREADS */
 142
 143 static int make_pidfile(char *devname)
 144 {
 145         char path[100];
 146         char pid[10];
 147         int fd;
 148         int n;
 149
 150         if (mkdir(MDMON_DIR, 0755) < 0 &&
 151             errno != EEXIST)
 152                 return -errno;
 153         sprintf(path, "%s/%s.pid", MDMON_DIR, devname);
 154
 155         fd = open(path, O_RDWR|O_CREAT|O_EXCL, 0600);
 156         if (fd < 0)
 157                 return -errno;
 158         sprintf(pid, "%d\n", getpid());
 159         n = write(fd, pid, strlen(pid));
 160         close(fd);
 161         if (n < 0)
 162                 return -errno;
 163         return 0;
 164 }
 165
 166 static void try_kill_monitor(pid_t pid, char *devname, int sock)
 167 {
 168         char buf[100];
 169         int fd;
 170         int n;
 171         long fl;
 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         n = read(fd, buf, sizeof(buf)-1);
 184         buf[sizeof(buf)-1] = 0;
 185         close(fd);
 186
 187         if (n < 0 || !strstr(buf, "mdmon"))
 188                 return;
 189
 190         kill(pid, SIGTERM);
 191
 192         /* Wait for monitor to exit by reading from the socket, after
 193          * clearing the non-blocking flag */
 194         fl = fcntl(sock, F_GETFL, 0);
 195         fl &= ~O_NONBLOCK;
 196         fcntl(sock, F_SETFL, fl);
 197         n = read(sock, buf, 100);
 198         /* Ignore result, it is just the wait that
 199          * matters
 200          */
 201 }
 202
 203 void remove_pidfile(char *devname)
 204 {
 205         char buf[100];
 206
 207         sprintf(buf, "%s/%s.pid", MDMON_DIR, devname);
 208         unlink(buf);
 209         sprintf(buf, "%s/%s.sock", MDMON_DIR, devname);
 210         unlink(buf);
 211 }
 212
 213 static int make_control_sock(char *devname)
 214 {
 215         char path[100];
 216         int sfd;
 217         long fl;
 218         struct sockaddr_un addr;
 219
 220         if (sigterm)
 221                 return -1;
 222
 223         sprintf(path, "%s/%s.sock", MDMON_DIR, devname);
 224         unlink(path);
 225         sfd = socket(PF_LOCAL, SOCK_STREAM, 0);
 226         if (sfd < 0)
 227                 return -1;
 228
 229         addr.sun_family = PF_LOCAL;
 230         strcpy(addr.sun_path, path);
 231         if (bind(sfd, &addr, sizeof(addr)) < 0) {
 232                 close(sfd);
 233                 return -1;
 234         }
 235         listen(sfd, 10);
 236         fl = fcntl(sfd, F_GETFL, 0);
 237         fl |= O_NONBLOCK;
 238         fcntl(sfd, F_SETFL, fl);
 239         return sfd;
 240 }
 241
 242 static void term(int sig)
 243 {
 244         sigterm = 1;
 245 }
 246
 247 static void wake_me(int sig)
 248 {
 249
 250 }
 251
 252 /* if we are debugging and starting mdmon by hand then don't fork */
 253 static int do_fork(void)
 254 {
 255         #ifdef DEBUG
 256         if (check_env("MDADM_NO_MDMON"))
 257                 return 0;
 258         #endif
 259
 260         return 1;
 261 }
 262
 263 void usage(void)
 264 {
 265         fprintf(stderr, "Usage: mdmon [--all] [--takeover] CONTAINER\n");
 266         exit(2);
 267 }
 268
 269 static int mdmon(char *devname, int devnum, int must_fork, int takeover);
 270
 271 int main(int argc, char *argv[])
 272 {
 273         char *container_name = NULL;
 274         int devnum;
 275         char *devname;
 276         int status = 0;
 277         int arg;
 278         int all = 0;
 279         int takeover = 0;
 280
 281         for (arg = 1; arg < argc; arg++) {
 282                 if (strncmp(argv[arg], "--all",5) == 0 ||
 283                     strcmp(argv[arg], "/proc/mdstat") == 0) {
 284                         container_name = argv[arg];
 285                         all = 1;
 286                 } else if (strcmp(argv[arg], "--takeover") == 0)
 287                         takeover = 1;
 288                 else if (container_name == NULL)
 289                         container_name = argv[arg];
 290                 else
 291                         usage();
 292         }
 293         if (container_name == NULL)
 294                 usage();
 295
 296         if (all) {
 297                 struct mdstat_ent *mdstat, *e;
 298                 int container_len = strlen(container_name);
 299
 300                 /* launch an mdmon instance for each container found */
 301                 mdstat = mdstat_read(0, 0);
 302                 for (e = mdstat; e; e = e->next) {
 303                         if (strncmp(e->metadata_version, "external:", 9) == 0 &&
 304                             !is_subarray(&e->metadata_version[9])) {
 305                                 devname = devnum2devname(e->devnum);
 306                                 /* update cmdline so this mdmon instance can be
 307                                  * distinguished from others in a call to ps(1)
 308                                  */
 309                                 if (strlen(devname) <= (unsigned)container_len) {
 310                                         memset(container_name, 0, container_len);
 311                                         sprintf(container_name, "%s", devname);
 312                                 }
 313                                 status |= mdmon(devname, e->devnum, 1,
 314                                                 takeover);
 315                         }
 316                 }
 317                 free_mdstat(mdstat);
 318
 319                 return status;
 320         } else if (strncmp(container_name, "md", 2) == 0) {
 321                 devnum = devname2devnum(container_name);
 322                 devname = devnum2devname(devnum);
 323                 if (strcmp(container_name, devname) != 0)
 324                         devname = NULL;
 325         } else {
 326                 struct stat st;
 327
 328                 devnum = NoMdDev;
 329                 if (stat(container_name, &st) == 0)
 330                         devnum = stat2devnum(&st);
 331                 if (devnum == NoMdDev)
 332                         devname = NULL;
 333                 else
 334                         devname = devnum2devname(devnum);
 335         }
 336
 337         if (!devname) {
 338                 fprintf(stderr, "mdmon: %s is not a valid md device name\n",
 339                         container_name);
 340                 exit(1);
 341         }
 342         return mdmon(devname, devnum, do_fork(), takeover);
 343 }
 344
 345 static int mdmon(char *devname, int devnum, int must_fork, int takeover)
 346 {
 347         int mdfd;
 348         struct mdinfo *mdi, *di;
 349         struct supertype *container;
 350         sigset_t set;
 351         struct sigaction act;
 352         int pfd[2];
 353         int status;
 354         int ignore;
 355         pid_t victim = -1;
 356         int victim_sock = -1;
 357
 358         dprintf("starting mdmon for %s\n", devname);
 359
 360         mdfd = open_dev(devnum);
 361         if (mdfd < 0) {
 362                 fprintf(stderr, "mdmon: %s: %s\n", devname,
 363                         strerror(errno));
 364                 return 1;
 365         }
 366         if (md_get_version(mdfd) < 0) {
 367                 fprintf(stderr, "mdmon: %s: Not an md device\n",
 368                         devname);
 369                 return 1;
 370         }
 371
 372         /* Fork, and have the child tell us when they are ready */
 373         if (must_fork) {
 374                 if (pipe(pfd) != 0) {
 375                         fprintf(stderr, "mdmon: failed to create pipe\n");
 376                         return 1;
 377                 }
 378                 switch(fork()) {
 379                 case -1:
 380                         fprintf(stderr, "mdmon: failed to fork: %s\n",
 381                                 strerror(errno));
 382                         return 1;
 383                 case 0: /* child */
 384                         close(pfd[0]);
 385                         break;
 386                 default: /* parent */
 387                         close(pfd[1]);
 388                         if (read(pfd[0], &status, sizeof(status)) != sizeof(status)) {
 389                                 wait(&status);
 390                                 status = WEXITSTATUS(status);
 391                         }
 392                         return status;
 393                 }
 394         } else
 395                 pfd[0] = pfd[1] = -1;
 396
 397         container = calloc(1, sizeof(*container));
 398         container->devnum = devnum;
 399         container->devname = devname;
 400         container->arrays = NULL;
 401         container->subarray[0] = 0;
 402         container->sock = -1;
 403
 404         if (!container->devname) {
 405                 fprintf(stderr, "mdmon: failed to allocate container name string\n");
 406                 exit(3);
 407         }
 408
 409         mdi = sysfs_read(mdfd, container->devnum, GET_VERSION|GET_LEVEL|GET_DEVS);
 410
 411         if (!mdi) {
 412                 fprintf(stderr, "mdmon: failed to load sysfs info for %s\n",
 413                         container->devname);
 414                 exit(3);
 415         }
 416         if (mdi->array.level != UnSet) {
 417                 fprintf(stderr, "mdmon: %s is not a container - cannot monitor\n",
 418                         devname);
 419                 exit(3);
 420         }
 421         if (mdi->array.major_version != -1 ||
 422             mdi->array.minor_version != -2) {
 423                 fprintf(stderr, "mdmon: %s does not use external metadata - cannot monitor\n",
 424                         devname);
 425                 exit(3);
 426         }
 427
 428         container->ss = version_to_superswitch(mdi->text_version);
 429         if (container->ss == NULL) {
 430                 fprintf(stderr, "mdmon: %s uses unsupported metadata: %s\n",
 431                         devname, mdi->text_version);
 432                 exit(3);
 433         }
 434
 435         container->devs = NULL;
 436         for (di = mdi->devs; di; di = di->next) {
 437                 struct mdinfo *cd = malloc(sizeof(*cd));
 438                 *cd = *di;
 439                 cd->next = container->devs;
 440                 container->devs = cd;
 441         }
 442         sysfs_free(mdi);
 443
 444         /* SIGUSR is sent between parent and child.  So both block it
 445          * and enable it only with pselect.
 446          */
 447         sigemptyset(&set);
 448         sigaddset(&set, SIGUSR1);
 449         sigaddset(&set, SIGTERM);
 450         sigprocmask(SIG_BLOCK, &set, NULL);
 451         act.sa_handler = wake_me;
 452         act.sa_flags = 0;
 453         sigaction(SIGUSR1, &act, NULL);
 454         act.sa_handler = term;
 455         sigaction(SIGTERM, &act, NULL);
 456         act.sa_handler = SIG_IGN;
 457         sigaction(SIGPIPE, &act, NULL);
 458
 459         victim = mdmon_pid(container->devnum);
 460         if (victim >= 0)
 461                 victim_sock = connect_monitor(container->devname);
 462
 463         ignore = chdir("/");
 464         if (!takeover && victim > 0 && victim_sock >= 0) {
 465                 if (fping_monitor(victim_sock) == 0) {
 466                         fprintf(stderr, "mdmon: %s already managed\n",
 467                                 container->devname);
 468                         exit(3);
 469                 }
 470                 close(victim_sock);
 471         }
 472         if (container->ss->load_super(container, mdfd, devname)) {
 473                 fprintf(stderr, "mdmon: Cannot load metadata for %s\n",
 474                         devname);
 475                 exit(3);
 476         }
 477         close(mdfd);
 478
 479         /* Ok, this is close enough.  We can say goodbye to our parent now.
 480          */
 481         if (victim > 0)
 482                 remove_pidfile(devname);
 483         if (make_pidfile(devname) < 0) {
 484                 exit(3);
 485         }
 486         container->sock = make_control_sock(devname);
 487
 488         status = 0;
 489         if (write(pfd[1], &status, sizeof(status)) < 0)
 490                 fprintf(stderr, "mdmon: failed to notify our parent: %d\n",
 491                         getppid());
 492         close(pfd[1]);
 493
 494         mlockall(MCL_CURRENT | 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         if (victim > 0) {
 503                 try_kill_monitor(victim, container->devname, victim_sock);
 504                 close(victim_sock);
 505         }
 506
 507         setsid();
 508         close(0);
 509         open("/dev/null", O_RDWR);
 510         close(1);
 511         ignore = dup(0);
 512 #ifndef DEBUG
 513         close(2);
 514         ignore = dup(0);
 515 #endif
 516
 517         do_manager(container);
 518
 519         exit(0);
 520 }