msg.c

   1 /*
   2  * Copyright (C) 2008 Intel Corporation
   3  *
   4  *      mdmon socket / message handling
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19 #ifndef _GNU_SOURCE
  20 #define _GNU_SOURCE
  21 #endif
  22 #include <unistd.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <stdlib.h>
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <sys/types.h>
  29 #include <sys/socket.h>
  30 #include <sys/un.h>
  31 #include "mdadm.h"
  32 #include "mdmon.h"
  33
  34 static const __u32 start_magic = 0x5a5aa5a5;
  35 static const __u32 end_magic = 0xa5a55a5a;
  36
  37 static int send_buf(int fd, const void* buf, int len, int tmo)
  38 {
  39         fd_set set;
  40         int rv;
  41         struct timeval timeout = {tmo, 0};
  42         struct timeval *ptmo = tmo ? &timeout : NULL;
  43
  44         while (len) {
  45                 FD_ZERO(&set);
  46                 FD_SET(fd, &set);
  47                 rv = select(fd+1, NULL, &set, NULL, ptmo);
  48                 if (rv <= 0)
  49                         return -1;
  50                 rv = write(fd, buf, len);
  51                 if (rv <= 0)
  52                         return -1;
  53                 len -= rv;
  54                 buf += rv;
  55         }
  56         return 0;
  57 }
  58
  59 static int recv_buf(int fd, void* buf, int len, int tmo)
  60 {
  61         fd_set set;
  62         int rv;
  63         struct timeval timeout = {tmo, 0};
  64         struct timeval *ptmo = tmo ? &timeout : NULL;
  65
  66         while (len) {
  67                 FD_ZERO(&set);
  68                 FD_SET(fd, &set);
  69                 rv = select(fd+1, &set, NULL, NULL, ptmo);
  70                 if (rv <= 0)
  71                         return -1;
  72                 rv = read(fd, buf, len);
  73                 if (rv <= 0)
  74                         return -1;
  75                 len -= rv;
  76                 buf += rv;
  77         }
  78         return 0;
  79 }
  80
  81
  82 int send_message(int fd, struct metadata_update *msg, int tmo)
  83 {
  84         __s32 len = msg->len;
  85         int rv;
  86
  87         rv = send_buf(fd, &start_magic, 4, tmo);
  88         rv = rv ?: send_buf(fd, &len, 4, tmo);
  89         if (len > 0)
  90                 rv = rv ?: send_buf(fd, msg->buf, msg->len, tmo);
  91         rv = send_buf(fd, &end_magic, 4, tmo);
  92
  93         return rv;
  94 }
  95
  96 int receive_message(int fd, struct metadata_update *msg, int tmo)
  97 {
  98         __u32 magic;
  99         __s32 len;
 100         int rv;
 101
 102         rv = recv_buf(fd, &magic, 4, tmo);
 103         if (rv < 0 || magic != start_magic)
 104                 return -1;
 105         rv = recv_buf(fd, &len, 4, tmo);
 106         if (rv < 0 || len > MSG_MAX_LEN)
 107                 return -1;
 108         if (len > 0) {
 109                 msg->buf = xmalloc(len);
 110                 rv = recv_buf(fd, msg->buf, len, tmo);
 111                 if (rv < 0) {
 112                         free(msg->buf);
 113                         return -1;
 114                 }
 115         } else
 116                 msg->buf = NULL;
 117         rv = recv_buf(fd, &magic, 4, tmo);
 118         if (rv < 0 || magic != end_magic) {
 119                 free(msg->buf);
 120                 return -1;
 121         }
 122         msg->len = len;
 123         return 0;
 124 }
 125
 126 int ack(int fd, int tmo)
 127 {
 128         struct metadata_update msg = { .len = 0 };
 129
 130         return send_message(fd, &msg, tmo);
 131 }
 132
 133 int wait_reply(int fd, int tmo)
 134 {
 135         struct metadata_update msg;
 136         int err = receive_message(fd, &msg, tmo);
 137
 138         /* mdmon sent extra data, but caller only cares that we got a
 139          * successful reply
 140          */
 141         if (err == 0 && msg.len > 0)
 142                 free(msg.buf);
 143
 144         return err;
 145 }
 146
 147 int connect_monitor(char *devname)
 148 {
 149         char path[100];
 150         int sfd;
 151         long fl;
 152         struct sockaddr_un addr;
 153         int pos;
 154         char *c;
 155
 156         pos = sprintf(path, "%s/", MDMON_DIR);
 157         if (is_subarray(devname)) {
 158                 devname++;
 159                 c = strchr(devname, '/');
 160                 if (!c)
 161                         return -1;
 162                 snprintf(&path[pos], c - devname + 1, "%s", devname);
 163                 pos += c - devname;
 164         } else
 165                 pos += sprintf(&path[pos], "%s", devname);
 166         sprintf(&path[pos], ".sock");
 167
 168         sfd = socket(PF_LOCAL, SOCK_STREAM, 0);
 169         if (sfd < 0)
 170                 return -1;
 171
 172         addr.sun_family = PF_LOCAL;
 173         strcpy(addr.sun_path, path);
 174         if (connect(sfd, &addr, sizeof(addr)) < 0) {
 175                 close(sfd);
 176                 return -1;
 177         }
 178
 179         fl = fcntl(sfd, F_GETFL, 0);
 180         fl |= O_NONBLOCK;
 181         fcntl(sfd, F_SETFL, fl);
 182
 183         return sfd;
 184 }
 185
 186 int fping_monitor(int sfd)
 187 {
 188         int err = 0;
 189
 190         if (sfd < 0)
 191                 return sfd;
 192
 193         /* try to ping existing socket */
 194         if (ack(sfd, 20) != 0)
 195                 err = -1;
 196
 197         /* check the reply */
 198         if (!err && wait_reply(sfd, 20) != 0)
 199                 err = -1;
 200
 201         return err;
 202 }
 203
 204 /* give the monitor a chance to update the metadata */
 205 int ping_monitor(char *devname)
 206 {
 207         int sfd = connect_monitor(devname);
 208         int err;
 209
 210         if (sfd >= 0) {
 211                 err = fping_monitor(sfd);
 212                 close(sfd);
 213         } else
 214                 err = -1;
 215
 216         return err;
 217 }
 218
 219 static char *ping_monitor_version(char *devname)
 220 {
 221         int sfd = connect_monitor(devname);
 222         struct metadata_update msg;
 223         int err = 0;
 224
 225         if (sfd < 0)
 226                 return NULL;
 227
 228         if (ack(sfd, 20) != 0)
 229                 err = -1;
 230
 231         if (!err && receive_message(sfd, &msg, 20) != 0)
 232                 err = -1;
 233
 234         close(sfd);
 235
 236         if (err || !msg.len || !msg.buf)
 237                 return NULL;
 238         return msg.buf;
 239 }
 240
 241 int unblock_subarray(struct mdinfo *sra, const int unfreeze)
 242 {
 243         char buf[64];
 244         int rc = 0;
 245
 246         if (sra) {
 247                 sprintf(buf, "external:%s\n", sra->text_version);
 248                 buf[9] = '/';
 249         } else
 250                 buf[9] = '-';
 251
 252         if (buf[9] == '-' ||
 253             sysfs_set_str(sra, NULL, "metadata_version", buf) ||
 254             (unfreeze &&
 255              sysfs_attribute_available(sra, NULL, "sync_action") &&
 256              sysfs_set_str(sra, NULL, "sync_action", "idle")))
 257                 rc = -1;
 258         return rc;
 259 }
 260
 261 int block_subarray(struct mdinfo *sra)
 262 {
 263         char buf[64];
 264         int rc = 0;
 265
 266         sprintf(buf, "external:%s\n", sra->text_version);
 267         buf[9] = '-';
 268         if (sysfs_set_str(sra, NULL, "metadata_version", buf))
 269                 rc = -1;
 270
 271         return rc;
 272 }
 273
 274 /* check mdmon version if it supports
 275  * array blocking mechanism
 276  */
 277 int check_mdmon_version(char *container)
 278 {
 279         char *version = NULL;
 280
 281         if (!mdmon_running(container)) {
 282                 /* if mdmon is not active we assume that any instance that is
 283                  * later started will match the current mdadm version, if this
 284                  * assumption is violated we may inadvertantly rebuild an array
 285                  * that was meant for reshape, or start rebuild on a spare that
 286                  * was to be moved to another container
 287                  */
 288                 /* pass */;
 289         } else {
 290                 int ver;
 291
 292                 version = ping_monitor_version(container);
 293                 ver = version ? mdadm_version(version) : -1;
 294                 free(version);
 295                 if (ver < 3002000) {
 296                         pr_err("mdmon instance for %s cannot be disabled\n",
 297                                container);
 298                         return -1;
 299                 }
 300         }
 301
 302         return 0;
 303 }
 304
 305 /**
 306  * block_monitor - prevent mdmon spare assignment
 307  * @container - container to block
 308  * @freeze - flag to additionally freeze sync_action
 309  *
 310  * This is used by the reshape code to freeze the container, and the
 311  * auto-rebuild implementation to atomically move spares.
 312  * In both cases we need to stop mdmon from assigning spares to replace
 313  * failed devices as we might have other plans for the spare.
 314  * For the reshape case we also need to 'freeze' sync_action so that
 315  * no recovery happens until we have fully prepared for the reshape.
 316  *
 317  * We tell mdmon that the array is frozen by marking the 'metadata' name
 318  * with a leading '-'.  The previously told mdmon "Don't make this array
 319  * read/write, leave it readonly".  Now it means a more general "Don't
 320  * reconfigure this array at all".
 321  * As older versions of mdmon (which might run from initrd) don't understand
 322  * this, we first check that the running mdmon is new enough.
 323  */
 324 int block_monitor(char *container, const int freeze)
 325 {
 326         struct mdstat_ent *ent, *e, *e2;
 327         struct mdinfo *sra = NULL;
 328         char buf[64];
 329         int rv = 0;
 330
 331         if (check_mdmon_version(container))
 332                 return -1;
 333
 334         ent = mdstat_read(0, 0);
 335         if (!ent) {
 336                 pr_err("failed to read /proc/mdstat while disabling mdmon\n");
 337                 return -1;
 338         }
 339
 340         /* freeze container contents */
 341         for (e = ent; e; e = e->next) {
 342                 if (!is_container_member(e, container))
 343                         continue;
 344                 sysfs_free(sra);
 345                 sra = sysfs_read(-1, e->devnm, GET_VERSION);
 346                 if (!sra) {
 347                         pr_err("failed to read sysfs for subarray%s\n",
 348                                to_subarray(e, container));
 349                         break;
 350                 }
 351                 /* can't reshape an array that we can't monitor */
 352                 if (sra->text_version[0] == '-')
 353                         break;
 354
 355                 if (freeze && sysfs_freeze_array(sra) < 1)
 356                         break;
 357                 /* flag this array to not be modified by mdmon (close race with
 358                  * takeover in reshape case and spare reassignment in the
 359                  * auto-rebuild case)
 360                  */
 361                 if (block_subarray(sra))
 362                         break;
 363                 ping_monitor(container);
 364
 365                 /* check that we did not race with recovery */
 366                 if ((freeze &&
 367                      !sysfs_attribute_available(sra, NULL, "sync_action")) ||
 368                     (freeze &&
 369                      sysfs_attribute_available(sra, NULL, "sync_action") &&
 370                      sysfs_get_str(sra, NULL, "sync_action", buf, 20) > 0 &&
 371                      strcmp(buf, "frozen\n") == 0))
 372                         /* pass */;
 373                 else {
 374                         unblock_subarray(sra, 0);
 375                         break;
 376                 }
 377                 /* Double check against races - there should be no spares
 378                  * or part-spares
 379                  */
 380                 sysfs_free(sra);
 381                 sra = sysfs_read(-1, e->devnm, GET_DEVS | GET_STATE);
 382                 if (sra && sra->array.spare_disks > 0) {
 383                         unblock_subarray(sra, freeze);
 384                         break;
 385                 }
 386         }
 387
 388         if (e) {
 389                 pr_err("failed to freeze subarray%s\n",
 390                         to_subarray(e, container));
 391
 392                 /* thaw the partially frozen container */
 393                 for (e2 = ent; e2 && e2 != e; e2 = e2->next) {
 394                         if (!is_container_member(e2, container))
 395                                 continue;
 396                         sysfs_free(sra);
 397                         sra = sysfs_read(-1, e2->devnm, GET_VERSION);
 398                         if (unblock_subarray(sra, freeze))
 399                                 pr_err("Failed to unfreeze %s\n", e2->dev);
 400                 }
 401
 402                 ping_monitor(container); /* cleared frozen */
 403                 rv = -1;
 404         }
 405
 406         sysfs_free(sra);
 407         free_mdstat(ent);
 408
 409         return rv;
 410 }
 411
 412 void unblock_monitor(char *container, const int unfreeze)
 413 {
 414         struct mdstat_ent *ent, *e;
 415         struct mdinfo *sra = NULL;
 416         int to_ping = 0;
 417
 418         ent = mdstat_read(0, 0);
 419         if (!ent) {
 420                 pr_err("failed to read /proc/mdstat while unblocking container\n");
 421                 return;
 422         }
 423
 424         /* unfreeze container contents */
 425         for (e = ent; e; e = e->next) {
 426                 if (!is_container_member(e, container))
 427                         continue;
 428                 sysfs_free(sra);
 429                 sra = sysfs_read(-1, e->devnm, GET_VERSION|GET_LEVEL);
 430                 if (!sra)
 431                         continue;
 432                 if (sra->array.level > 0)
 433                         to_ping++;
 434                 if (unblock_subarray(sra, unfreeze))
 435                         pr_err("Failed to unfreeze %s\n", e->dev);
 436         }
 437         if (to_ping)
 438                 ping_monitor(container);
 439
 440         sysfs_free(sra);
 441         free_mdstat(ent);
 442 }
 443
 444 /* give the manager a chance to view the updated container state.  This
 445  * would naturally happen due to the manager noticing a change in
 446  * /proc/mdstat; however, pinging encourages this detection to happen
 447  * while an exclusive open() on the container is active
 448  */
 449 int ping_manager(char *devname)
 450 {
 451         int sfd = connect_monitor(devname);
 452         struct metadata_update msg = { .len = -1 };
 453         int err = 0;
 454
 455         if (sfd < 0)
 456                 return sfd;
 457
 458         err = send_message(sfd, &msg, 20);
 459
 460         /* check the reply */
 461         if (!err && wait_reply(sfd, 20) != 0)
 462                 err = -1;
 463
 464         close(sfd);
 465         return err;
 466 }
 467
 468 /* using takeover operation for grow purposes, mdadm has to be sure
 469  * that mdmon processes all updates, and if necessary it will be closed
 470  * at takeover to raid0 operation
 471   */
 472 void flush_mdmon(char *container)
 473 {
 474         ping_manager(container);
 475         ping_monitor(container);
 476 }