ctdb/server/ctdb_lock.c

   1 /*
   2    ctdb lock handling
   3    provide API to do non-blocking locks for single or all databases
   4
   5    Copyright (C) Amitay Isaacs  2012
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, see <http://www.gnu.org/licenses/>.
  19 */
  20 #include "replace.h"
  21 #include "system/filesys.h"
  22 #include "system/network.h"
  23
  24 #include <talloc.h>
  25 #include <tevent.h>
  26
  27 #include "lib/tdb_wrap/tdb_wrap.h"
  28 #include "lib/util/dlinklist.h"
  29 #include "lib/util/debug.h"
  30 #include "lib/util/samba_util.h"
  31 #include "lib/util/sys_rw.h"
  32
  33 #include "ctdb_private.h"
  34
  35 #include "common/common.h"
  36 #include "common/logging.h"
  37
  38 /*
  39  * Non-blocking Locking API
  40  *
  41  * 1. Create a child process to do blocking locks.
  42  * 2. Once the locks are obtained, signal parent process via fd.
  43  * 3. Invoke registered callback routine with locking status.
  44  * 4. If the child process cannot get locks within certain time,
  45  *    execute an external script to debug.
  46  *
  47  * ctdb_lock_record()      - get a lock on a record
  48  * ctdb_lock_db()          - get a lock on a DB
  49  *
  50  *  auto_mark              - whether to mark/unmark DBs in before/after callback
  51  *                           = false is used for freezing databases for
  52  *                           recovery since the recovery cannot start till
  53  *                           databases are locked on all the nodes.
  54  *                           = true is used for record locks.
  55  */
  56
  57 enum lock_type {
  58         LOCK_RECORD,
  59         LOCK_DB,
  60 };
  61
  62 static const char * const lock_type_str[] = {
  63         "lock_record",
  64         "lock_db",
  65 };
  66
  67 struct lock_request;
  68
  69 /* lock_context is the common part for a lock request */
  70 struct lock_context {
  71         struct lock_context *next, *prev;
  72         enum lock_type type;
  73         struct ctdb_context *ctdb;
  74         struct ctdb_db_context *ctdb_db;
  75         TDB_DATA key;
  76         uint32_t priority;
  77         bool auto_mark;
  78         struct lock_request *request;
  79         pid_t child;
  80         int fd[2];
  81         struct tevent_fd *tfd;
  82         struct tevent_timer *ttimer;
  83         struct timeval start_time;
  84         uint32_t key_hash;
  85         bool can_schedule;
  86 };
  87
  88 /* lock_request is the client specific part for a lock request */
  89 struct lock_request {
  90         struct lock_context *lctx;
  91         void (*callback)(void *, bool);
  92         void *private_data;
  93 };
  94
  95
  96 int ctdb_db_iterator(struct ctdb_context *ctdb, ctdb_db_handler_t handler,
  97                      void *private_data)
  98 {
  99         struct ctdb_db_context *ctdb_db;
 100         int ret;
 101
 102         for (ctdb_db = ctdb->db_list; ctdb_db; ctdb_db = ctdb_db->next) {
 103                 ret = handler(ctdb_db, private_data);
 104                 if (ret != 0) {
 105                         return -1;
 106                 }
 107         }
 108
 109         return 0;
 110 }
 111
 112 /*
 113  * lock all databases - mark only
 114  */
 115 static int db_lock_mark_handler(struct ctdb_db_context *ctdb_db,
 116                                 void *private_data)
 117 {
 118         int tdb_transaction_write_lock_mark(struct tdb_context *);
 119
 120         DEBUG(DEBUG_INFO, ("marking locked database %s\n", ctdb_db->db_name));
 121
 122         if (tdb_transaction_write_lock_mark(ctdb_db->ltdb->tdb) != 0) {
 123                 DEBUG(DEBUG_ERR, ("Failed to mark (transaction lock) database %s\n",
 124                                   ctdb_db->db_name));
 125                 return -1;
 126         }
 127
 128         if (tdb_lockall_mark(ctdb_db->ltdb->tdb) != 0) {
 129                 DEBUG(DEBUG_ERR, ("Failed to mark (all lock) database %s\n",
 130                                   ctdb_db->db_name));
 131                 return -1;
 132         }
 133
 134         return 0;
 135 }
 136
 137 int ctdb_lockdb_mark(struct ctdb_db_context *ctdb_db)
 138 {
 139         if (!ctdb_db_frozen(ctdb_db)) {
 140                 DEBUG(DEBUG_ERR,
 141                       ("Attempt to mark database locked when not frozen\n"));
 142                 return -1;
 143         }
 144
 145         return db_lock_mark_handler(ctdb_db, NULL);
 146 }
 147
 148 /*
 149  * lock all databases - unmark only
 150  */
 151 static int db_lock_unmark_handler(struct ctdb_db_context *ctdb_db,
 152                                   void *private_data)
 153 {
 154         int tdb_transaction_write_lock_unmark(struct tdb_context *);
 155
 156         DEBUG(DEBUG_INFO, ("unmarking locked database %s\n", ctdb_db->db_name));
 157
 158         if (tdb_transaction_write_lock_unmark(ctdb_db->ltdb->tdb) != 0) {
 159                 DEBUG(DEBUG_ERR, ("Failed to unmark (transaction lock) database %s\n",
 160                                   ctdb_db->db_name));
 161                 return -1;
 162         }
 163
 164         if (tdb_lockall_unmark(ctdb_db->ltdb->tdb) != 0) {
 165                 DEBUG(DEBUG_ERR, ("Failed to unmark (all lock) database %s\n",
 166                                   ctdb_db->db_name));
 167                 return -1;
 168         }
 169
 170         return 0;
 171 }
 172
 173 int ctdb_lockdb_unmark(struct ctdb_db_context *ctdb_db)
 174 {
 175         if (!ctdb_db_frozen(ctdb_db)) {
 176                 DEBUG(DEBUG_ERR,
 177                       ("Attempt to unmark database locked when not frozen\n"));
 178                 return -1;
 179         }
 180
 181         return db_lock_unmark_handler(ctdb_db, NULL);
 182 }
 183
 184 static void ctdb_lock_schedule(struct ctdb_context *ctdb);
 185
 186 /*
 187  * Destructor to kill the child locking process
 188  */
 189 static int ctdb_lock_context_destructor(struct lock_context *lock_ctx)
 190 {
 191         if (lock_ctx->request) {
 192                 lock_ctx->request->lctx = NULL;
 193         }
 194         if (lock_ctx->child > 0) {
 195                 ctdb_kill(lock_ctx->ctdb, lock_ctx->child, SIGTERM);
 196                 if (lock_ctx->type == LOCK_RECORD) {
 197                         DLIST_REMOVE(lock_ctx->ctdb_db->lock_current, lock_ctx);
 198                 } else {
 199                         DLIST_REMOVE(lock_ctx->ctdb->lock_current, lock_ctx);
 200                 }
 201                 if (lock_ctx->ctdb_db->lock_num_current == 0) {
 202                         ctdb_fatal(NULL, "Lock count is 0 before decrement\n");
 203                 }
 204                 lock_ctx->ctdb_db->lock_num_current--;
 205                 CTDB_DECREMENT_STAT(lock_ctx->ctdb, locks.num_current);
 206                 CTDB_DECREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_current);
 207         } else {
 208                 if (lock_ctx->type == LOCK_RECORD) {
 209                         DLIST_REMOVE(lock_ctx->ctdb_db->lock_pending, lock_ctx);
 210                 } else {
 211                         DLIST_REMOVE(lock_ctx->ctdb->lock_pending, lock_ctx);
 212                 }
 213                 CTDB_DECREMENT_STAT(lock_ctx->ctdb, locks.num_pending);
 214                 CTDB_DECREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_pending);
 215         }
 216
 217         ctdb_lock_schedule(lock_ctx->ctdb);
 218
 219         return 0;
 220 }
 221
 222
 223 /*
 224  * Destructor to remove lock request
 225  */
 226 static int ctdb_lock_request_destructor(struct lock_request *lock_request)
 227 {
 228         if (lock_request->lctx == NULL) {
 229                 return 0;
 230         }
 231
 232         lock_request->lctx->request = NULL;
 233         TALLOC_FREE(lock_request->lctx);
 234
 235         return 0;
 236 }
 237
 238 /*
 239  * Process all the callbacks waiting for lock
 240  *
 241  * If lock has failed, callback is executed with locked=false
 242  */
 243 static void process_callbacks(struct lock_context *lock_ctx, bool locked)
 244 {
 245         struct lock_request *request;
 246         bool auto_mark = lock_ctx->auto_mark;
 247
 248         if (auto_mark && locked) {
 249                 switch (lock_ctx->type) {
 250                 case LOCK_RECORD:
 251                         tdb_chainlock_mark(lock_ctx->ctdb_db->ltdb->tdb, lock_ctx->key);
 252                         break;
 253
 254                 case LOCK_DB:
 255                         (void)ctdb_lockdb_mark(lock_ctx->ctdb_db);
 256                         break;
 257                 }
 258         }
 259
 260         request = lock_ctx->request;
 261         if (auto_mark) {
 262                 /* Since request may be freed in the callback, unset the lock
 263                  * context, so request destructor will not free lock context.
 264                  */
 265                 request->lctx = NULL;
 266         }
 267
 268         /* Since request may be freed in the callback, unset the request */
 269         lock_ctx->request = NULL;
 270
 271         request->callback(request->private_data, locked);
 272
 273         if (!auto_mark) {
 274                 return;
 275         }
 276
 277         if (locked) {
 278                 switch (lock_ctx->type) {
 279                 case LOCK_RECORD:
 280                         tdb_chainlock_unmark(lock_ctx->ctdb_db->ltdb->tdb, lock_ctx->key);
 281                         break;
 282
 283                 case LOCK_DB:
 284                         ctdb_lockdb_unmark(lock_ctx->ctdb_db);
 285                         break;
 286                 }
 287         }
 288
 289         talloc_free(lock_ctx);
 290 }
 291
 292
 293 static int lock_bucket_id(double t)
 294 {
 295         double ms = 1.e-3, s = 1;
 296         int id;
 297
 298         if (t < 1*ms) {
 299                 id = 0;
 300         } else if (t < 10*ms) {
 301                 id = 1;
 302         } else if (t < 100*ms) {
 303                 id = 2;
 304         } else if (t < 1*s) {
 305                 id = 3;
 306         } else if (t < 2*s) {
 307                 id = 4;
 308         } else if (t < 4*s) {
 309                 id = 5;
 310         } else if (t < 8*s) {
 311                 id = 6;
 312         } else if (t < 16*s) {
 313                 id = 7;
 314         } else if (t < 32*s) {
 315                 id = 8;
 316         } else if (t < 64*s) {
 317                 id = 9;
 318         } else {
 319                 id = 10;
 320         }
 321
 322         return id;
 323 }
 324
 325 /*
 326  * Callback routine when the required locks are obtained.
 327  * Called from parent context
 328  */
 329 static void ctdb_lock_handler(struct tevent_context *ev,
 330                             struct tevent_fd *tfd,
 331                             uint16_t flags,
 332                             void *private_data)
 333 {
 334         struct lock_context *lock_ctx;
 335         char c;
 336         bool locked;
 337         double t;
 338         int id;
 339
 340         lock_ctx = talloc_get_type_abort(private_data, struct lock_context);
 341
 342         /* cancel the timeout event */
 343         TALLOC_FREE(lock_ctx->ttimer);
 344
 345         t = timeval_elapsed(&lock_ctx->start_time);
 346         id = lock_bucket_id(t);
 347
 348         /* Read the status from the child process */
 349         if (sys_read(lock_ctx->fd[0], &c, 1) != 1) {
 350                 locked = false;
 351         } else {
 352                 locked = (c == 0 ? true : false);
 353         }
 354
 355         /* Update statistics */
 356         CTDB_INCREMENT_STAT(lock_ctx->ctdb, locks.num_calls);
 357         CTDB_INCREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_calls);
 358
 359         if (locked) {
 360                 CTDB_INCREMENT_STAT(lock_ctx->ctdb, locks.buckets[id]);
 361                 CTDB_UPDATE_LATENCY(lock_ctx->ctdb, lock_ctx->ctdb_db,
 362                                     lock_type_str[lock_ctx->type], locks.latency,
 363                                     lock_ctx->start_time);
 364
 365                 CTDB_UPDATE_DB_LATENCY(lock_ctx->ctdb_db, lock_type_str[lock_ctx->type], locks.latency, t);
 366                 CTDB_INCREMENT_DB_STAT(lock_ctx->ctdb_db, locks.buckets[id]);
 367         } else {
 368                 CTDB_INCREMENT_STAT(lock_ctx->ctdb, locks.num_failed);
 369                 CTDB_INCREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_failed);
 370         }
 371
 372         process_callbacks(lock_ctx, locked);
 373 }
 374
 375 struct lock_log_entry {
 376         struct db_hash_context *lock_log;
 377         TDB_DATA key;
 378         unsigned long log_sec;
 379         struct tevent_timer *timer;
 380 };
 381
 382 static int lock_log_fetch_parser(uint8_t *keybuf, size_t keylen,
 383                                  uint8_t *databuf, size_t datalen,
 384                                  void *private_data)
 385 {
 386         struct lock_log_entry **entry =
 387                 (struct lock_log_entry **)private_data;
 388
 389         if (datalen != sizeof(struct lock_log_entry *)) {
 390                 return EINVAL;
 391         }
 392
 393         *entry = talloc_get_type_abort(*(void **)databuf,
 394                                        struct lock_log_entry);
 395         return 0;
 396 }
 397
 398 static void lock_log_cleanup(struct tevent_context *ev,
 399                              struct tevent_timer *ttimer,
 400                              struct timeval current_time,
 401                              void *private_data)
 402 {
 403         struct lock_log_entry *entry = talloc_get_type_abort(
 404                 private_data, struct lock_log_entry);
 405         int ret;
 406
 407         entry->timer = NULL;
 408
 409         ret = db_hash_delete(entry->lock_log, entry->key.dptr,
 410                              entry->key.dsize);
 411         if (ret != 0) {
 412                 return;
 413         }
 414         talloc_free(entry);
 415 }
 416
 417 static bool lock_log_skip(struct tevent_context *ev,
 418                           struct db_hash_context *lock_log,
 419                           TDB_DATA key, unsigned long elapsed_sec)
 420 {
 421         struct lock_log_entry *entry = NULL;
 422         int ret;
 423
 424         ret = db_hash_fetch(lock_log, key.dptr, key.dsize,
 425                             lock_log_fetch_parser, &entry);
 426         if (ret == ENOENT) {
 427
 428                 entry = talloc_zero(lock_log, struct lock_log_entry);
 429                 if (entry == NULL) {
 430                         goto fail;
 431                 }
 432
 433                 entry->lock_log = lock_log;
 434
 435                 entry->key.dptr = talloc_memdup(entry, key.dptr, key.dsize);
 436                 if (entry->key.dptr == NULL) {
 437                         talloc_free(entry);
 438                         goto fail;
 439                 }
 440                 entry->key.dsize = key.dsize;
 441
 442                 entry->log_sec = elapsed_sec;
 443                 entry->timer = tevent_add_timer(ev, entry,
 444                                                 timeval_current_ofs(30, 0),
 445                                                 lock_log_cleanup, entry);
 446                 if (entry->timer == NULL) {
 447                         talloc_free(entry);
 448                         goto fail;
 449                 }
 450
 451                 ret = db_hash_add(lock_log, key.dptr, key.dsize,
 452                                   (uint8_t *)&entry,
 453                                   sizeof(struct lock_log_entry *));
 454                 if (ret != 0) {
 455                         talloc_free(entry);
 456                         goto fail;
 457                 }
 458
 459                 return false;
 460
 461         } else if (ret == EINVAL) {
 462
 463                 ret = db_hash_delete(lock_log, key.dptr, key.dsize);
 464                 if (ret != 0) {
 465                         goto fail;
 466                 }
 467
 468                 return false;
 469
 470         } else if (ret == 0) {
 471
 472                 if (elapsed_sec <= entry->log_sec) {
 473                         return true;
 474                 }
 475
 476                 entry->log_sec = elapsed_sec;
 477
 478                 TALLOC_FREE(entry->timer);
 479                 entry->timer = tevent_add_timer(ev, entry,
 480                                                 timeval_current_ofs(30, 0),
 481                                                 lock_log_cleanup, entry);
 482                 if (entry->timer == NULL) {
 483                         ret = db_hash_delete(lock_log, key.dptr, key.dsize);
 484                         if (ret != 0) {
 485                                 goto fail;
 486                         }
 487                         talloc_free(entry);
 488                 }
 489
 490                 return false;
 491         }
 492
 493
 494 fail:
 495         return false;
 496
 497 }
 498
 499 /*
 500  * Callback routine when required locks are not obtained within timeout
 501  * Called from parent context
 502  */
 503 static void ctdb_lock_timeout_handler(struct tevent_context *ev,
 504                                     struct tevent_timer *ttimer,
 505                                     struct timeval current_time,
 506                                     void *private_data)
 507 {
 508         static char debug_locks[PATH_MAX+1] = "";
 509         struct lock_context *lock_ctx;
 510         struct ctdb_context *ctdb;
 511         pid_t pid;
 512         double elapsed_time;
 513         bool skip;
 514         char *keystr;
 515
 516         lock_ctx = talloc_get_type_abort(private_data, struct lock_context);
 517         ctdb = lock_ctx->ctdb;
 518
 519         elapsed_time = timeval_elapsed(&lock_ctx->start_time);
 520
 521         /* For database locks, always log */
 522         if (lock_ctx->type == LOCK_DB) {
 523                 DEBUG(DEBUG_WARNING,
 524                       ("Unable to get DB lock on database %s for "
 525                        "%.0lf seconds\n",
 526                        lock_ctx->ctdb_db->db_name, elapsed_time));
 527                 goto lock_debug;
 528         }
 529
 530         /* For record locks, check if we have already logged */
 531         skip = lock_log_skip(ev, lock_ctx->ctdb_db->lock_log,
 532                              lock_ctx->key, (unsigned long)elapsed_time);
 533         if (skip) {
 534                 goto skip_lock_debug;
 535         }
 536
 537         keystr = hex_encode_talloc(lock_ctx, lock_ctx->key.dptr,
 538                                    lock_ctx->key.dsize);
 539         DEBUG(DEBUG_WARNING,
 540               ("Unable to get RECORD lock on database %s for %.0lf seconds"
 541                " (key %s)\n",
 542                lock_ctx->ctdb_db->db_name, elapsed_time,
 543                keystr ? keystr : ""));
 544         TALLOC_FREE(keystr);
 545
 546         /* If a node stopped/banned, don't spam the logs */
 547         if (ctdb->nodes[ctdb->pnn]->flags & NODE_FLAGS_INACTIVE) {
 548                 goto skip_lock_debug;
 549         }
 550
 551 lock_debug:
 552
 553         if (ctdb_set_helper("lock debugging helper",
 554                             debug_locks, sizeof(debug_locks),
 555                             "CTDB_DEBUG_LOCKS",
 556                             getenv("CTDB_BASE"), "debug_locks.sh")) {
 557                 pid = vfork();
 558                 if (pid == 0) {
 559                         execl(debug_locks, debug_locks, NULL);
 560                         _exit(0);
 561                 }
 562                 ctdb_track_child(ctdb, pid);
 563         } else {
 564                 DEBUG(DEBUG_WARNING,
 565                       (__location__
 566                        " Unable to setup lock debugging\n"));
 567         }
 568
 569 skip_lock_debug:
 570
 571         /* reset the timeout timer */
 572         // talloc_free(lock_ctx->ttimer);
 573         lock_ctx->ttimer = tevent_add_timer(ctdb->ev,
 574                                             lock_ctx,
 575                                             timeval_current_ofs(10, 0),
 576                                             ctdb_lock_timeout_handler,
 577                                             (void *)lock_ctx);
 578 }
 579
 580 static bool lock_helper_args(TALLOC_CTX *mem_ctx,
 581                              struct lock_context *lock_ctx, int fd,
 582                              int *argc, const char ***argv)
 583 {
 584         const char **args = NULL;
 585         int nargs = 0, i;
 586
 587         switch (lock_ctx->type) {
 588         case LOCK_RECORD:
 589                 nargs = 6;
 590                 break;
 591
 592         case LOCK_DB:
 593                 nargs = 5;
 594                 break;
 595         }
 596
 597         /* Add extra argument for null termination */
 598         nargs++;
 599
 600         args = talloc_array(mem_ctx, const char *, nargs);
 601         if (args == NULL) {
 602                 return false;
 603         }
 604
 605         args[0] = talloc_asprintf(args, "%d", getpid());
 606         args[1] = talloc_asprintf(args, "%d", fd);
 607
 608         switch (lock_ctx->type) {
 609         case LOCK_RECORD:
 610                 args[2] = talloc_strdup(args, "RECORD");
 611                 args[3] = talloc_strdup(args, lock_ctx->ctdb_db->db_path);
 612                 args[4] = talloc_asprintf(args, "0x%x",
 613                                 tdb_get_flags(lock_ctx->ctdb_db->ltdb->tdb));
 614                 if (lock_ctx->key.dsize == 0) {
 615                         args[5] = talloc_strdup(args, "NULL");
 616                 } else {
 617                         args[5] = hex_encode_talloc(args, lock_ctx->key.dptr, lock_ctx->key.dsize);
 618                 }
 619                 break;
 620
 621         case LOCK_DB:
 622                 args[2] = talloc_strdup(args, "DB");
 623                 args[3] = talloc_strdup(args, lock_ctx->ctdb_db->db_path);
 624                 args[4] = talloc_asprintf(args, "0x%x",
 625                                 tdb_get_flags(lock_ctx->ctdb_db->ltdb->tdb));
 626                 break;
 627         }
 628
 629         /* Make sure last argument is NULL */
 630         args[nargs-1] = NULL;
 631
 632         for (i=0; i<nargs-1; i++) {
 633                 if (args[i] == NULL) {
 634                         talloc_free(args);
 635                         return false;
 636                 }
 637         }
 638
 639         *argc = nargs;
 640         *argv = args;
 641         return true;
 642 }
 643
 644 /*
 645  * Find a lock request that can be scheduled
 646  */
 647 static struct lock_context *ctdb_find_lock_context(struct ctdb_context *ctdb)
 648 {
 649         struct lock_context *lock_ctx, *next_ctx;
 650         struct ctdb_db_context *ctdb_db;
 651
 652         /* First check if there are database lock requests */
 653
 654         for (lock_ctx = ctdb->lock_pending; lock_ctx != NULL;
 655              lock_ctx = next_ctx) {
 656
 657                 if (lock_ctx->request != NULL) {
 658                         /* Found a lock context with a request */
 659                         return lock_ctx;
 660                 }
 661
 662                 next_ctx = lock_ctx->next;
 663
 664                 DEBUG(DEBUG_INFO, ("Removing lock context without lock "
 665                                    "request\n"));
 666                 DLIST_REMOVE(ctdb->lock_pending, lock_ctx);
 667                 CTDB_DECREMENT_STAT(ctdb, locks.num_pending);
 668                 CTDB_DECREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_pending);
 669                 talloc_free(lock_ctx);
 670         }
 671
 672         /* Next check database queues */
 673         for (ctdb_db = ctdb->db_list; ctdb_db; ctdb_db = ctdb_db->next) {
 674                 if (ctdb_db->lock_num_current ==
 675                     ctdb->tunable.lock_processes_per_db) {
 676                         continue;
 677                 }
 678
 679                 for (lock_ctx = ctdb_db->lock_pending; lock_ctx != NULL;
 680                      lock_ctx = next_ctx) {
 681
 682                         next_ctx = lock_ctx->next;
 683
 684                         if (lock_ctx->request != NULL) {
 685                                 return lock_ctx;
 686                         }
 687
 688                         DEBUG(DEBUG_INFO, ("Removing lock context without "
 689                                            "lock request\n"));
 690                         DLIST_REMOVE(ctdb_db->lock_pending, lock_ctx);
 691                         CTDB_DECREMENT_STAT(ctdb, locks.num_pending);
 692                         CTDB_DECREMENT_DB_STAT(ctdb_db, locks.num_pending);
 693                         talloc_free(lock_ctx);
 694                 }
 695         }
 696
 697         return NULL;
 698 }
 699
 700 /*
 701  * Schedule a new lock child process
 702  * Set up callback handler and timeout handler
 703  */
 704 static void ctdb_lock_schedule(struct ctdb_context *ctdb)
 705 {
 706         struct lock_context *lock_ctx;
 707         int ret, argc;
 708         TALLOC_CTX *tmp_ctx;
 709         static char prog[PATH_MAX+1] = "";
 710         const char **args;
 711
 712         if (!ctdb_set_helper("lock helper",
 713                              prog, sizeof(prog),
 714                              "CTDB_LOCK_HELPER",
 715                              CTDB_HELPER_BINDIR, "ctdb_lock_helper")) {
 716                 ctdb_die(ctdb, __location__
 717                          " Unable to set lock helper\n");
 718         }
 719
 720         /* Find a lock context with requests */
 721         lock_ctx = ctdb_find_lock_context(ctdb);
 722         if (lock_ctx == NULL) {
 723                 return;
 724         }
 725
 726         lock_ctx->child = -1;
 727         ret = pipe(lock_ctx->fd);
 728         if (ret != 0) {
 729                 DEBUG(DEBUG_ERR, ("Failed to create pipe in ctdb_lock_schedule\n"));
 730                 return;
 731         }
 732
 733         set_close_on_exec(lock_ctx->fd[0]);
 734
 735         /* Create data for child process */
 736         tmp_ctx = talloc_new(lock_ctx);
 737         if (tmp_ctx == NULL) {
 738                 DEBUG(DEBUG_ERR, ("Failed to allocate memory for helper args\n"));
 739                 close(lock_ctx->fd[0]);
 740                 close(lock_ctx->fd[1]);
 741                 return;
 742         }
 743
 744         if (! ctdb->do_setsched) {
 745                 ret = setenv("CTDB_NOSETSCHED", "1", 1);
 746                 if (ret != 0) {
 747                         DEBUG(DEBUG_WARNING,
 748                               ("Failed to set CTDB_NOSETSCHED variable\n"));
 749                 }
 750         }
 751
 752         /* Create arguments for lock helper */
 753         if (!lock_helper_args(tmp_ctx, lock_ctx, lock_ctx->fd[1],
 754                               &argc, &args)) {
 755                 DEBUG(DEBUG_ERR, ("Failed to create lock helper args\n"));
 756                 close(lock_ctx->fd[0]);
 757                 close(lock_ctx->fd[1]);
 758                 talloc_free(tmp_ctx);
 759                 return;
 760         }
 761
 762         lock_ctx->child = ctdb_vfork_exec(lock_ctx, ctdb, prog, argc,
 763                                           (const char **)args);
 764         if (lock_ctx->child == -1) {
 765                 DEBUG(DEBUG_ERR, ("Failed to create a child in ctdb_lock_schedule\n"));
 766                 close(lock_ctx->fd[0]);
 767                 close(lock_ctx->fd[1]);
 768                 talloc_free(tmp_ctx);
 769                 return;
 770         }
 771
 772         /* Parent process */
 773         close(lock_ctx->fd[1]);
 774
 775         talloc_free(tmp_ctx);
 776
 777         /* Set up timeout handler */
 778         lock_ctx->ttimer = tevent_add_timer(ctdb->ev,
 779                                             lock_ctx,
 780                                             timeval_current_ofs(10, 0),
 781                                             ctdb_lock_timeout_handler,
 782                                             (void *)lock_ctx);
 783         if (lock_ctx->ttimer == NULL) {
 784                 ctdb_kill(ctdb, lock_ctx->child, SIGTERM);
 785                 lock_ctx->child = -1;
 786                 close(lock_ctx->fd[0]);
 787                 return;
 788         }
 789
 790         /* Set up callback */
 791         lock_ctx->tfd = tevent_add_fd(ctdb->ev,
 792                                       lock_ctx,
 793                                       lock_ctx->fd[0],
 794                                       TEVENT_FD_READ,
 795                                       ctdb_lock_handler,
 796                                       (void *)lock_ctx);
 797         if (lock_ctx->tfd == NULL) {
 798                 TALLOC_FREE(lock_ctx->ttimer);
 799                 ctdb_kill(ctdb, lock_ctx->child, SIGTERM);
 800                 lock_ctx->child = -1;
 801                 close(lock_ctx->fd[0]);
 802                 return;
 803         }
 804         tevent_fd_set_auto_close(lock_ctx->tfd);
 805
 806         /* Move the context from pending to current */
 807         if (lock_ctx->type == LOCK_RECORD) {
 808                 DLIST_REMOVE(lock_ctx->ctdb_db->lock_pending, lock_ctx);
 809                 DLIST_ADD_END(lock_ctx->ctdb_db->lock_current, lock_ctx);
 810         } else {
 811                 DLIST_REMOVE(ctdb->lock_pending, lock_ctx);
 812                 DLIST_ADD_END(ctdb->lock_current, lock_ctx);
 813         }
 814         CTDB_DECREMENT_STAT(lock_ctx->ctdb, locks.num_pending);
 815         CTDB_INCREMENT_STAT(lock_ctx->ctdb, locks.num_current);
 816         lock_ctx->ctdb_db->lock_num_current++;
 817         CTDB_DECREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_pending);
 818         CTDB_INCREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_current);
 819 }
 820
 821
 822 /*
 823  * Lock record / db depending on type
 824  */
 825 static struct lock_request *ctdb_lock_internal(TALLOC_CTX *mem_ctx,
 826                                                struct ctdb_context *ctdb,
 827                                                struct ctdb_db_context *ctdb_db,
 828                                                TDB_DATA key,
 829                                                uint32_t priority,
 830                                                void (*callback)(void *, bool),
 831                                                void *private_data,
 832                                                enum lock_type type,
 833                                                bool auto_mark)
 834 {
 835         struct lock_context *lock_ctx = NULL;
 836         struct lock_request *request;
 837
 838         if (callback == NULL) {
 839                 DEBUG(DEBUG_WARNING, ("No callback function specified, not locking\n"));
 840                 return NULL;
 841         }
 842
 843         lock_ctx = talloc_zero(ctdb, struct lock_context);
 844         if (lock_ctx == NULL) {
 845                 DEBUG(DEBUG_ERR, ("Failed to create a new lock context\n"));
 846                 return NULL;
 847         }
 848
 849         if ((request = talloc_zero(mem_ctx, struct lock_request)) == NULL) {
 850                 talloc_free(lock_ctx);
 851                 return NULL;
 852         }
 853
 854         lock_ctx->type = type;
 855         lock_ctx->ctdb = ctdb;
 856         lock_ctx->ctdb_db = ctdb_db;
 857         lock_ctx->key.dsize = key.dsize;
 858         if (key.dsize > 0) {
 859                 lock_ctx->key.dptr = talloc_memdup(lock_ctx, key.dptr, key.dsize);
 860                 if (lock_ctx->key.dptr == NULL) {
 861                         DEBUG(DEBUG_ERR, (__location__ "Memory allocation error\n"));
 862                         talloc_free(lock_ctx);
 863                         talloc_free(request);
 864                         return NULL;
 865                 }
 866                 lock_ctx->key_hash = ctdb_hash(&key);
 867         } else {
 868                 lock_ctx->key.dptr = NULL;
 869         }
 870         lock_ctx->priority = priority;
 871         lock_ctx->auto_mark = auto_mark;
 872
 873         lock_ctx->request = request;
 874         lock_ctx->child = -1;
 875
 876         /* Non-record locks are required by recovery and should be scheduled
 877          * immediately, so keep them at the head of the pending queue.
 878          */
 879         if (lock_ctx->type == LOCK_RECORD) {
 880                 DLIST_ADD_END(ctdb_db->lock_pending, lock_ctx);
 881         } else {
 882                 DLIST_ADD_END(ctdb->lock_pending, lock_ctx);
 883         }
 884         CTDB_INCREMENT_STAT(ctdb, locks.num_pending);
 885         if (ctdb_db) {
 886                 CTDB_INCREMENT_DB_STAT(ctdb_db, locks.num_pending);
 887         }
 888
 889         /* Start the timer when we activate the context */
 890         lock_ctx->start_time = timeval_current();
 891
 892         request->lctx = lock_ctx;
 893         request->callback = callback;
 894         request->private_data = private_data;
 895
 896         talloc_set_destructor(request, ctdb_lock_request_destructor);
 897         talloc_set_destructor(lock_ctx, ctdb_lock_context_destructor);
 898
 899         ctdb_lock_schedule(ctdb);
 900
 901         return request;
 902 }
 903
 904
 905 /*
 906  * obtain a lock on a record in a database
 907  */
 908 struct lock_request *ctdb_lock_record(TALLOC_CTX *mem_ctx,
 909                                       struct ctdb_db_context *ctdb_db,
 910                                       TDB_DATA key,
 911                                       bool auto_mark,
 912                                       void (*callback)(void *, bool),
 913                                       void *private_data)
 914 {
 915         return ctdb_lock_internal(mem_ctx,
 916                                   ctdb_db->ctdb,
 917                                   ctdb_db,
 918                                   key,
 919                                   0,
 920                                   callback,
 921                                   private_data,
 922                                   LOCK_RECORD,
 923                                   auto_mark);
 924 }
 925
 926
 927 /*
 928  * obtain a lock on a database
 929  */
 930 struct lock_request *ctdb_lock_db(TALLOC_CTX *mem_ctx,
 931                                   struct ctdb_db_context *ctdb_db,
 932                                   bool auto_mark,
 933                                   void (*callback)(void *, bool),
 934                                   void *private_data)
 935 {
 936         return ctdb_lock_internal(mem_ctx,
 937                                   ctdb_db->ctdb,
 938                                   ctdb_db,
 939                                   tdb_null,
 940                                   0,
 941                                   callback,
 942                                   private_data,
 943                                   LOCK_DB,
 944                                   auto_mark);
 945 }