mdmon.c

   1
   2 /*
   3  * md array manager.
   4  * When md arrays have user-space managed metadata, this is the program
   5  * that does the managing.
   6  *
   7  * Given one argument: the name of the array (e.g. /dev/md0) that is
   8  * the container.
   9  * We fork off a helper that runs high priority and mlocked.  It responds to
  10  * device failures and other events that might stop writeout, or that are
  11  * trivial to deal with.
  12  * The main thread then watches for new arrays being created in the container
  13  * and starts monitoring them too ... along with a few other tasks.
  14  *
  15  * The main thread communicates with the priority thread by writing over
  16  * a pipe.
  17  * Separate programs can communicate with the main thread via Unix-domain
  18  * socket.
  19  * The two threads share address space and open file table.
  20  *
  21  */
  22
  23 #ifndef _GNU_SOURCE
  24 #define _GNU_SOURCE
  25 #endif
  26
  27 #include        <unistd.h>
  28 #include        <stdlib.h>
  29 #include        <sys/types.h>
  30 #include        <sys/stat.h>
  31 #include        <sys/socket.h>
  32 #include        <sys/un.h>
  33 #include        <sys/mman.h>
  34 #include        <sys/syscall.h>
  35 #include        <stdio.h>
  36 #include        <errno.h>
  37 #include        <string.h>
  38 #include        <fcntl.h>
  39 #include        <signal.h>
  40
  41 #include        <sched.h>
  42
  43 #include        "mdadm.h"
  44 #include        "mdmon.h"
  45
  46 struct active_array *discard_this;
  47 struct active_array *pending_discard;
  48
  49 int mon_tid, mgr_tid;
  50
  51 int run_child(void *v)
  52 {
  53         struct supertype *c = v;
  54
  55         do_monitor(c);
  56         return 0;
  57 }
  58
  59 int clone_monitor(struct supertype *container)
  60 {
  61         static char stack[4096];
  62
  63         mon_tid = clone(run_child, stack+4096-64,
  64                    CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD,
  65                    container);
  66
  67         mgr_tid = syscall(SYS_gettid);
  68
  69         return mon_tid;
  70 }
  71
  72 static struct superswitch *find_metadata_methods(char *vers)
  73 {
  74         if (strcmp(vers, "ddf") == 0)
  75                 return &super_ddf;
  76         if (strcmp(vers, "imsm") == 0)
  77                 return &super_imsm;
  78         return NULL;
  79 }
  80
  81
  82 static int make_pidfile(char *devname, int o_excl)
  83 {
  84         char path[100];
  85         char pid[10];
  86         int fd;
  87         sprintf(path, "/var/run/mdadm/%s.pid", devname);
  88
  89         fd = open(path, O_RDWR|O_CREAT|o_excl, 0600);
  90         if (fd < 0)
  91                 return -1;
  92         sprintf(pid, "%d\n", getpid());
  93         write(fd, pid, strlen(pid));
  94         close(fd);
  95         return 0;
  96 }
  97
  98 static void try_kill_monitor(char *devname)
  99 {
 100         char buf[100];
 101         int fd;
 102         pid_t pid;
 103
 104         sprintf(buf, "/var/run/mdadm/%s.pid", devname);
 105         fd = open(buf, O_RDONLY);
 106         if (fd < 0)
 107                 return;
 108
 109         if (read(fd, buf, sizeof(buf)) < 0) {
 110                 close(fd);
 111                 return;
 112         }
 113
 114         close(fd);
 115         pid = strtoul(buf, NULL, 10);
 116
 117         /* kill this process if it is mdmon */
 118         sprintf(buf, "/proc/%lu/cmdline", (unsigned long) pid);
 119         fd = open(buf, O_RDONLY);
 120         if (fd < 0)
 121                 return;
 122
 123         if (read(fd, buf, sizeof(buf)) < 0) {
 124                 close(fd);
 125                 return;
 126         }
 127
 128         if (strstr(buf, "mdmon") != NULL)
 129                 kill(pid, SIGTERM);
 130 }
 131
 132 void remove_pidfile(char *devname)
 133 {
 134         char buf[100];
 135
 136         sprintf(buf, "/var/run/mdadm/%s.pid", devname);
 137         unlink(buf);
 138 }
 139
 140 static int make_control_sock(char *devname)
 141 {
 142         char path[100];
 143         int sfd;
 144         long fl;
 145         struct sockaddr_un addr;
 146
 147         sprintf(path, "/var/run/mdadm/%s.sock", devname);
 148         unlink(path);
 149         sfd = socket(PF_LOCAL, SOCK_STREAM, 0);
 150         if (sfd < 0)
 151                 return -1;
 152
 153         addr.sun_family = PF_LOCAL;
 154         strcpy(addr.sun_path, path);
 155         if (bind(sfd, &addr, sizeof(addr)) < 0) {
 156                 close(sfd);
 157                 return -1;
 158         }
 159         listen(sfd, 10);
 160         fl = fcntl(sfd, F_GETFL, 0);
 161         fl |= O_NONBLOCK;
 162         fcntl(sfd, F_SETFL, fl);
 163         return sfd;
 164 }
 165
 166 static void wake_me(int sig)
 167 {
 168
 169 }
 170
 171 int main(int argc, char *argv[])
 172 {
 173         int mdfd;
 174         struct mdinfo *mdi, *di;
 175         struct supertype *container;
 176         sigset_t set;
 177         struct sigaction act;
 178
 179         if (argc != 2) {
 180                 fprintf(stderr, "Usage: md-manage /device/name/for/container\n");
 181                 exit(2);
 182         }
 183         mdfd = open(argv[1], O_RDWR);
 184         if (mdfd < 0) {
 185                 fprintf(stderr, "md-manage: %s: %s\n", argv[1],
 186                         strerror(errno));
 187                 exit(1);
 188         }
 189         if (md_get_version(mdfd) < 0) {
 190                 fprintf(stderr, "md-manage: %s: Not an md device\n",
 191                         argv[1]);
 192                 exit(1);
 193         }
 194
 195         /* hopefully it is a container - we'll check later */
 196
 197         container = malloc(sizeof(*container));
 198         container->devnum = fd2devnum(mdfd);
 199         container->devname = devnum2devname(container->devnum);
 200         container->device_name = argv[1];
 201
 202         /* If this fails, we hope it already exists */
 203         mkdir("/var/run/mdadm", 0600);
 204         /* pid file lives in /var/run/mdadm/mdXX.pid */
 205         if (make_pidfile(container->devname, O_EXCL) < 0) {
 206                 if (ping_monitor(container->devname) == 0) {
 207                         fprintf(stderr, "mdmon: %s already managed\n",
 208                                 container->devname);
 209                         exit(3);
 210                 } else {
 211                         /* cleanup the old monitor, this one is taking over */
 212                         try_kill_monitor(container->devname);
 213                         if (make_pidfile(container->devname, 0) < 0) {
 214                                 fprintf(stderr, "mdmon: %s Cannot create pidfile\n",
 215                                         container->devname);
 216                                 exit(3);
 217                         }
 218                 }
 219         }
 220
 221         container->sock = make_control_sock(container->devname);
 222         if (container->sock < 0) {
 223                 fprintf(stderr, "mdmon: Cannot create socket in /var/run/mdadm\n");
 224                 exit(3);
 225         }
 226         container->arrays = NULL;
 227
 228         mdi = sysfs_read(mdfd, container->devnum,
 229                          GET_VERSION|GET_LEVEL|GET_DEVS);
 230
 231         if (!mdi) {
 232                 fprintf(stderr, "mdmon: failed to load sysfs info for %s\n",
 233                         container->devname);
 234                 exit(3);
 235         }
 236         if (mdi->array.level != UnSet) {
 237                 fprintf(stderr, "mdmon: %s is not a container - cannot monitor\n",
 238                         argv[1]);
 239                 exit(3);
 240         }
 241         if (mdi->array.major_version != -1 ||
 242             mdi->array.minor_version != -2) {
 243                 fprintf(stderr, "mdmon: %s does not use external metadata - cannot monitor\n",
 244                         argv[1]);
 245                 exit(3);
 246         }
 247
 248         container->ss = find_metadata_methods(mdi->text_version);
 249         if (container->ss == NULL) {
 250                 fprintf(stderr, "mdmon: %s uses unknown metadata: %s\n",
 251                         argv[1], mdi->text_version);
 252                 exit(3);
 253         }
 254
 255         container->devs = NULL;
 256         for (di = mdi->devs; di; di = di->next) {
 257                 struct mdinfo *cd = malloc(sizeof(*cd));
 258                 cd = di;
 259                 cd->next = container->devs;
 260                 container->devs = cd;
 261         }
 262         sysfs_free(mdi);
 263
 264
 265         if (container->ss->load_super(container, mdfd, argv[1])) {
 266                 fprintf(stderr, "mdmon: Cannot load metadata for %s\n",
 267                         argv[1]);
 268                 exit(3);
 269         }
 270
 271         mlockall(MCL_FUTURE);
 272
 273         /* SIGUSR is sent between parent and child.  So both block it
 274          * and enable it only with pselect.
 275          */
 276         sigemptyset(&set);
 277         sigaddset(&set, SIGUSR1);
 278         sigprocmask(SIG_BLOCK, &set, NULL);
 279         act.sa_handler = wake_me;
 280         act.sa_flags = 0;
 281         sigaction(SIGUSR1, &act, NULL);
 282         act.sa_handler = SIG_IGN;
 283         sigaction(SIGPIPE, &act, NULL);
 284
 285         if (clone_monitor(container) < 0) {
 286                 fprintf(stderr, "md-manage: failed to start monitor process: %s\n",
 287                         strerror(errno));
 288                 exit(2);
 289         }
 290
 291         do_manager(container);
 292
 293         exit(0);
 294 }