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 static int make_pidfile(char *devname)
 117 {
 118         char path[100];
 119         char pid[10];
 120         int fd;
 121         int n;
 122
 123         if (mkdir(pid_dir, 0600) < 0 &&
 124             errno != EEXIST)
 125                 return -errno;
 126         sprintf(path, "%s/%s.pid", pid_dir, 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         n = read(sock, buf, 100);
 183         /* Ignore result, it is just the wait that
 184          * matters
 185          */
 186 }
 187
 188 void remove_pidfile(char *devname)
 189 {
 190         char buf[100];
 191
 192         sprintf(buf, "%s/%s.pid", pid_dir, devname);
 193         unlink(buf);
 194         sprintf(buf, "%s/%s.sock", pid_dir, devname);
 195         unlink(buf);
 196         if (strcmp(pid_dir, ALT_RUN) == 0)
 197                 /* try to clean up when we are finished with this dir */
 198                 rmdir(pid_dir);
 199 }
 200
 201 static int make_control_sock(char *devname)
 202 {
 203         char path[100];
 204         int sfd;
 205         long fl;
 206         struct sockaddr_un addr;
 207
 208         if (sigterm)
 209                 return -1;
 210
 211         sprintf(path, "%s/%s.sock", pid_dir, devname);
 212         unlink(path);
 213         sfd = socket(PF_LOCAL, SOCK_STREAM, 0);
 214         if (sfd < 0)
 215                 return -1;
 216
 217         addr.sun_family = PF_LOCAL;
 218         strcpy(addr.sun_path, path);
 219         if (bind(sfd, &addr, sizeof(addr)) < 0) {
 220                 close(sfd);
 221                 return -1;
 222         }
 223         listen(sfd, 10);
 224         fl = fcntl(sfd, F_GETFL, 0);
 225         fl |= O_NONBLOCK;
 226         fcntl(sfd, F_SETFL, fl);
 227         return sfd;
 228 }
 229
 230 static void term(int sig)
 231 {
 232         sigterm = 1;
 233 }
 234
 235 static void wake_me(int sig)
 236 {
 237
 238 }
 239
 240 /* if we are debugging and starting mdmon by hand then don't fork */
 241 static int do_fork(void)
 242 {
 243         #ifdef DEBUG
 244         if (check_env("MDADM_NO_MDMON"))
 245                 return 0;
 246         #endif
 247
 248         return 1;
 249 }
 250
 251 void usage(void)
 252 {
 253         fprintf(stderr, "Usage: mdmon [--all] [--takeover] CONTAINER\n");
 254         exit(2);
 255 }
 256
 257 static int mdmon(char *devname, int devnum, int must_fork, int takeover);
 258
 259 int main(int argc, char *argv[])
 260 {
 261         char *container_name = NULL;
 262         int devnum;
 263         char *devname;
 264         int status = 0;
 265         int arg;
 266         int all = 0;
 267         int takeover = 0;
 268
 269         for (arg = 1; arg < argc; arg++) {
 270                 if (strncmp(argv[arg], "--all",5) == 0 ||
 271                     strcmp(argv[arg], "/proc/mdstat") == 0) {
 272                         container_name = argv[arg];
 273                         all = 1;
 274                 } else if (strcmp(argv[arg], "--takeover") == 0)
 275                         takeover = 1;
 276                 else if (container_name == NULL)
 277                         container_name = argv[arg];
 278                 else
 279                         usage();
 280         }
 281         if (container_name == NULL)
 282                 usage();
 283
 284         if (all) {
 285                 struct mdstat_ent *mdstat, *e;
 286                 int container_len = strlen(container_name);
 287
 288                 /* launch an mdmon instance for each container found */
 289                 mdstat = mdstat_read(0, 0);
 290                 for (e = mdstat; e; e = e->next) {
 291                         if (strncmp(e->metadata_version, "external:", 9) == 0 &&
 292                             !is_subarray(&e->metadata_version[9])) {
 293                                 devname = devnum2devname(e->devnum);
 294                                 /* update cmdline so this mdmon instance can be
 295                                  * distinguished from others in a call to ps(1)
 296                                  */
 297                                 if (strlen(devname) <= container_len) {
 298                                         memset(container_name, 0, container_len);
 299                                         sprintf(container_name, "%s", devname);
 300                                 }
 301                                 status |= mdmon(devname, e->devnum, 1,
 302                                                 takeover);
 303                         }
 304                 }
 305                 free_mdstat(mdstat);
 306
 307                 return status;
 308         } else if (strncmp(container_name, "md", 2) == 0) {
 309                 devnum = devname2devnum(container_name);
 310                 devname = devnum2devname(devnum);
 311                 if (strcmp(container_name, devname) != 0)
 312                         devname = NULL;
 313         } else {
 314                 struct stat st;
 315
 316                 devnum = NoMdDev;
 317                 if (stat(container_name, &st) == 0)
 318                         devnum = stat2devnum(&st);
 319                 if (devnum == NoMdDev)
 320                         devname = NULL;
 321                 else
 322                         devname = devnum2devname(devnum);
 323         }
 324
 325         if (!devname) {
 326                 fprintf(stderr, "mdmon: %s is not a valid md device name\n",
 327                         container_name);
 328                 exit(1);
 329         }
 330         return mdmon(devname, devnum, do_fork(), takeover);
 331 }
 332
 333 static int mdmon(char *devname, int devnum, int must_fork, int takeover)
 334 {
 335         int mdfd;
 336         struct mdinfo *mdi, *di;
 337         struct supertype *container;
 338         sigset_t set;
 339         struct sigaction act;
 340         int pfd[2];
 341         int status;
 342         int ignore;
 343         pid_t victim = -1;
 344         int victim_sock = -1;
 345
 346         dprintf("starting mdmon for %s\n", devname);
 347
 348         mdfd = open_dev(devnum);
 349         if (mdfd < 0) {
 350                 fprintf(stderr, "mdmon: %s: %s\n", devname,
 351                         strerror(errno));
 352                 return 1;
 353         }
 354         if (md_get_version(mdfd) < 0) {
 355                 fprintf(stderr, "mdmon: %s: Not an md device\n",
 356                         devname);
 357                 return 1;
 358         }
 359
 360         /* Fork, and have the child tell us when they are ready */
 361         if (must_fork) {
 362                 if (pipe(pfd) != 0) {
 363                         fprintf(stderr, "mdmon: failed to create pipe\n");
 364                         return 1;
 365                 }
 366                 switch(fork()) {
 367                 case -1:
 368                         fprintf(stderr, "mdmon: failed to fork: %s\n",
 369                                 strerror(errno));
 370                         return 1;
 371                 case 0: /* child */
 372                         close(pfd[0]);
 373                         break;
 374                 default: /* parent */
 375                         close(pfd[1]);
 376                         if (read(pfd[0], &status, sizeof(status)) != sizeof(status)) {
 377                                 wait(&status);
 378                                 status = WEXITSTATUS(status);
 379                         }
 380                         return status;
 381                 }
 382         } else
 383                 pfd[0] = pfd[1] = -1;
 384
 385         container = calloc(1, sizeof(*container));
 386         container->devnum = devnum;
 387         container->devname = devname;
 388         container->arrays = NULL;
 389         container->subarray[0] = 0;
 390         container->sock = -1;
 391
 392         if (!container->devname) {
 393                 fprintf(stderr, "mdmon: failed to allocate container name string\n");
 394                 exit(3);
 395         }
 396
 397         mdi = sysfs_read(mdfd, container->devnum,
 398                          GET_VERSION|GET_LEVEL|GET_DEVS|SKIP_GONE_DEVS);
 399
 400         if (!mdi) {
 401                 fprintf(stderr, "mdmon: failed to load sysfs info for %s\n",
 402                         container->devname);
 403                 exit(3);
 404         }
 405         if (mdi->array.level != UnSet) {
 406                 fprintf(stderr, "mdmon: %s is not a container - cannot monitor\n",
 407                         devname);
 408                 exit(3);
 409         }
 410         if (mdi->array.major_version != -1 ||
 411             mdi->array.minor_version != -2) {
 412                 fprintf(stderr, "mdmon: %s does not use external metadata - cannot monitor\n",
 413                         devname);
 414                 exit(3);
 415         }
 416
 417         container->ss = find_metadata_methods(mdi->text_version);
 418         if (container->ss == NULL) {
 419                 fprintf(stderr, "mdmon: %s uses unknown metadata: %s\n",
 420                         devname, mdi->text_version);
 421                 exit(3);
 422         }
 423
 424         container->devs = NULL;
 425         for (di = mdi->devs; di; di = di->next) {
 426                 struct mdinfo *cd = malloc(sizeof(*cd));
 427                 *cd = *di;
 428                 cd->next = container->devs;
 429                 container->devs = cd;
 430         }
 431         sysfs_free(mdi);
 432
 433         /* SIGUSR is sent between parent and child.  So both block it
 434          * and enable it only with pselect.
 435          */
 436         sigemptyset(&set);
 437         sigaddset(&set, SIGUSR1);
 438         sigaddset(&set, SIGTERM);
 439         sigprocmask(SIG_BLOCK, &set, NULL);
 440         act.sa_handler = wake_me;
 441         act.sa_flags = 0;
 442         sigaction(SIGUSR1, &act, NULL);
 443         act.sa_handler = term;
 444         sigaction(SIGTERM, &act, NULL);
 445         act.sa_handler = SIG_IGN;
 446         sigaction(SIGPIPE, &act, NULL);
 447
 448         pid_dir = VAR_RUN;
 449         victim = mdmon_pid(container->devnum);
 450         if (victim < 0) {
 451                 pid_dir = ALT_RUN;
 452                 victim = mdmon_pid(container->devnum);
 453         }
 454         if (victim >= 0)
 455                 victim_sock = connect_monitor(container->devname);
 456
 457         ignore = chdir("/");
 458         if (!takeover && victim > 0 && victim_sock >= 0) {
 459                 if (fping_monitor(victim_sock) == 0) {
 460                         fprintf(stderr, "mdmon: %s already managed\n",
 461                                 container->devname);
 462                         exit(3);
 463                 }
 464                 close(victim_sock);
 465         }
 466         if (container->ss->load_super(container, mdfd, devname)) {
 467                 fprintf(stderr, "mdmon: Cannot load metadata for %s\n",
 468                         devname);
 469                 exit(3);
 470         }
 471         close(mdfd);
 472
 473         /* Ok, this is close enough.  We can say goodbye to our parent now.
 474          */
 475         if (victim > 0)
 476                 remove_pidfile(devname);
 477         pid_dir = VAR_RUN;
 478         if (make_pidfile(devname) < 0) {
 479                 /* Try the alternate */
 480                 pid_dir = ALT_RUN;
 481                 if (make_pidfile(devname) < 0) {
 482                         fprintf(stderr, "mdmon: Neither %s nor %s are writable\n"
 483                                 "       cannot create .pid or .sock files.  Aborting\n",
 484                                 VAR_RUN, ALT_RUN);
 485                         exit(3);
 486                 }
 487         }
 488         container->sock = make_control_sock(devname);
 489
 490         status = 0;
 491         if (write(pfd[1], &status, sizeof(status)) < 0)
 492                 fprintf(stderr, "mdmon: failed to notify our parent: %d\n",
 493                         getppid());
 494         close(pfd[1]);
 495
 496         mlockall(MCL_CURRENT | MCL_FUTURE);
 497
 498         if (clone_monitor(container) < 0) {
 499                 fprintf(stderr, "mdmon: failed to start monitor process: %s\n",
 500                         strerror(errno));
 501                 exit(2);
 502         }
 503
 504         if (victim > 0) {
 505                 try_kill_monitor(victim, container->devname, victim_sock);
 506                 close(victim_sock);
 507         }
 508
 509         setsid();
 510         close(0);
 511         open("/dev/null", O_RDWR);
 512         close(1);
 513         ignore = dup(0);
 514 #ifndef DEBUG
 515         close(2);
 516         ignore = dup(0);
 517 #endif
 518
 519         do_manager(container);
 520
 521         exit(0);
 522 }