source3/lib/dbwrap_ctdb.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Database interface wrapper around ctdbd
   4    Copyright (C) Volker Lendecke 2007-2009
   5    Copyright (C) Michael Adam 2009
   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
  21 #include "includes.h"
  22 #ifdef CLUSTER_SUPPORT
  23 #include "ctdb.h"
  24 #include "ctdb_private.h"
  25 #include "ctdbd_conn.h"
  26 #include "g_lock.h"
  27
  28 struct db_ctdb_transaction_handle {
  29         struct db_ctdb_ctx *ctx;
  30         /*
  31          * we store the reads and writes done under a transaction:
  32          * - one list stores both reads and writes (m_all),
  33          * - the other just writes (m_write)
  34          */
  35         struct ctdb_marshall_buffer *m_all;
  36         struct ctdb_marshall_buffer *m_write;
  37         uint32_t nesting;
  38         bool nested_cancel;
  39         char *lock_name;
  40 };
  41
  42 struct db_ctdb_ctx {
  43         struct db_context *db;
  44         struct tdb_wrap *wtdb;
  45         uint32 db_id;
  46         struct db_ctdb_transaction_handle *transaction;
  47         struct g_lock_ctx *lock_ctx;
  48 };
  49
  50 struct db_ctdb_rec {
  51         struct db_ctdb_ctx *ctdb_ctx;
  52         struct ctdb_ltdb_header header;
  53         struct timeval lock_time;
  54 };
  55
  56 static NTSTATUS tdb_error_to_ntstatus(struct tdb_context *tdb)
  57 {
  58         NTSTATUS status;
  59         enum TDB_ERROR tret = tdb_error(tdb);
  60
  61         switch (tret) {
  62         case TDB_ERR_EXISTS:
  63                 status = NT_STATUS_OBJECT_NAME_COLLISION;
  64                 break;
  65         case TDB_ERR_NOEXIST:
  66                 status = NT_STATUS_OBJECT_NAME_NOT_FOUND;
  67                 break;
  68         default:
  69                 status = NT_STATUS_INTERNAL_DB_CORRUPTION;
  70                 break;
  71         }
  72
  73         return status;
  74 }
  75
  76
  77 /**
  78  * fetch a record from the tdb, separating out the header
  79  * information and returning the body of the record.
  80  */
  81 static NTSTATUS db_ctdb_ltdb_fetch(struct db_ctdb_ctx *db,
  82                                    TDB_DATA key,
  83                                    struct ctdb_ltdb_header *header,
  84                                    TALLOC_CTX *mem_ctx,
  85                                    TDB_DATA *data)
  86 {
  87         TDB_DATA rec;
  88         NTSTATUS status;
  89
  90         rec = tdb_fetch(db->wtdb->tdb, key);
  91         if (rec.dsize < sizeof(struct ctdb_ltdb_header)) {
  92                 status = NT_STATUS_NOT_FOUND;
  93                 if (data) {
  94                         ZERO_STRUCTP(data);
  95                 }
  96                 if (header) {
  97                         header->dmaster = (uint32_t)-1;
  98                         header->rsn = 0;
  99                 }
 100                 goto done;
 101         }
 102
 103         if (header) {
 104                 *header = *(struct ctdb_ltdb_header *)rec.dptr;
 105         }
 106
 107         if (data) {
 108                 data->dsize = rec.dsize - sizeof(struct ctdb_ltdb_header);
 109                 if (data->dsize == 0) {
 110                         data->dptr = NULL;
 111                 } else {
 112                         data->dptr = (unsigned char *)talloc_memdup(mem_ctx,
 113                                         rec.dptr
 114                                          + sizeof(struct ctdb_ltdb_header),
 115                                         data->dsize);
 116                         if (data->dptr == NULL) {
 117                                 status = NT_STATUS_NO_MEMORY;
 118                                 goto done;
 119                         }
 120                 }
 121         }
 122
 123         status = NT_STATUS_OK;
 124
 125 done:
 126         SAFE_FREE(rec.dptr);
 127         return status;
 128 }
 129
 130 /*
 131  * Store a record together with the ctdb record header
 132  * in the local copy of the database.
 133  */
 134 static NTSTATUS db_ctdb_ltdb_store(struct db_ctdb_ctx *db,
 135                                    TDB_DATA key,
 136                                    struct ctdb_ltdb_header *header,
 137                                    TDB_DATA data)
 138 {
 139         TALLOC_CTX *tmp_ctx = talloc_stackframe();
 140         TDB_DATA rec;
 141         int ret;
 142
 143         rec.dsize = data.dsize + sizeof(struct ctdb_ltdb_header);
 144         rec.dptr = (uint8_t *)talloc_size(tmp_ctx, rec.dsize);
 145
 146         if (rec.dptr == NULL) {
 147                 talloc_free(tmp_ctx);
 148                 return NT_STATUS_NO_MEMORY;
 149         }
 150
 151         memcpy(rec.dptr, header, sizeof(struct ctdb_ltdb_header));
 152         memcpy(sizeof(struct ctdb_ltdb_header) + (uint8_t *)rec.dptr, data.dptr, data.dsize);
 153
 154         ret = tdb_store(db->wtdb->tdb, key, rec, TDB_REPLACE);
 155
 156         talloc_free(tmp_ctx);
 157
 158         return (ret == 0) ? NT_STATUS_OK
 159                           : tdb_error_to_ntstatus(db->wtdb->tdb);
 160
 161 }
 162
 163 /*
 164   form a ctdb_rec_data record from a key/data pair
 165
 166   note that header may be NULL. If not NULL then it is included in the data portion
 167   of the record
 168  */
 169 static struct ctdb_rec_data *db_ctdb_marshall_record(TALLOC_CTX *mem_ctx, uint32_t reqid,
 170                                                   TDB_DATA key,
 171                                                   struct ctdb_ltdb_header *header,
 172                                                   TDB_DATA data)
 173 {
 174         size_t length;
 175         struct ctdb_rec_data *d;
 176
 177         length = offsetof(struct ctdb_rec_data, data) + key.dsize +
 178                 data.dsize + (header?sizeof(*header):0);
 179         d = (struct ctdb_rec_data *)talloc_size(mem_ctx, length);
 180         if (d == NULL) {
 181                 return NULL;
 182         }
 183         d->length = length;
 184         d->reqid = reqid;
 185         d->keylen = key.dsize;
 186         memcpy(&d->data[0], key.dptr, key.dsize);
 187         if (header) {
 188                 d->datalen = data.dsize + sizeof(*header);
 189                 memcpy(&d->data[key.dsize], header, sizeof(*header));
 190                 memcpy(&d->data[key.dsize+sizeof(*header)], data.dptr, data.dsize);
 191         } else {
 192                 d->datalen = data.dsize;
 193                 memcpy(&d->data[key.dsize], data.dptr, data.dsize);
 194         }
 195         return d;
 196 }
 197
 198
 199 /* helper function for marshalling multiple records */
 200 static struct ctdb_marshall_buffer *db_ctdb_marshall_add(TALLOC_CTX *mem_ctx,
 201                                                struct ctdb_marshall_buffer *m,
 202                                                uint64_t db_id,
 203                                                uint32_t reqid,
 204                                                TDB_DATA key,
 205                                                struct ctdb_ltdb_header *header,
 206                                                TDB_DATA data)
 207 {
 208         struct ctdb_rec_data *r;
 209         size_t m_size, r_size;
 210         struct ctdb_marshall_buffer *m2 = NULL;
 211
 212         r = db_ctdb_marshall_record(talloc_tos(), reqid, key, header, data);
 213         if (r == NULL) {
 214                 talloc_free(m);
 215                 return NULL;
 216         }
 217
 218         if (m == NULL) {
 219                 m = (struct ctdb_marshall_buffer *)talloc_zero_size(
 220                         mem_ctx, offsetof(struct ctdb_marshall_buffer, data));
 221                 if (m == NULL) {
 222                         goto done;
 223                 }
 224                 m->db_id = db_id;
 225         }
 226
 227         m_size = talloc_get_size(m);
 228         r_size = talloc_get_size(r);
 229
 230         m2 = (struct ctdb_marshall_buffer *)talloc_realloc_size(
 231                 mem_ctx, m,  m_size + r_size);
 232         if (m2 == NULL) {
 233                 talloc_free(m);
 234                 goto done;
 235         }
 236
 237         memcpy(m_size + (uint8_t *)m2, r, r_size);
 238
 239         m2->count++;
 240
 241 done:
 242         talloc_free(r);
 243         return m2;
 244 }
 245
 246 /* we've finished marshalling, return a data blob with the marshalled records */
 247 static TDB_DATA db_ctdb_marshall_finish(struct ctdb_marshall_buffer *m)
 248 {
 249         TDB_DATA data;
 250         data.dptr = (uint8_t *)m;
 251         data.dsize = talloc_get_size(m);
 252         return data;
 253 }
 254
 255 /*
 256    loop over a marshalling buffer
 257
 258      - pass r==NULL to start
 259      - loop the number of times indicated by m->count
 260 */
 261 static struct ctdb_rec_data *db_ctdb_marshall_loop_next(struct ctdb_marshall_buffer *m, struct ctdb_rec_data *r,
 262                                                      uint32_t *reqid,
 263                                                      struct ctdb_ltdb_header *header,
 264                                                      TDB_DATA *key, TDB_DATA *data)
 265 {
 266         if (r == NULL) {
 267                 r = (struct ctdb_rec_data *)&m->data[0];
 268         } else {
 269                 r = (struct ctdb_rec_data *)(r->length + (uint8_t *)r);
 270         }
 271
 272         if (reqid != NULL) {
 273                 *reqid = r->reqid;
 274         }
 275
 276         if (key != NULL) {
 277                 key->dptr   = &r->data[0];
 278                 key->dsize  = r->keylen;
 279         }
 280         if (data != NULL) {
 281                 data->dptr  = &r->data[r->keylen];
 282                 data->dsize = r->datalen;
 283                 if (header != NULL) {
 284                         data->dptr += sizeof(*header);
 285                         data->dsize -= sizeof(*header);
 286                 }
 287         }
 288
 289         if (header != NULL) {
 290                 if (r->datalen < sizeof(*header)) {
 291                         return NULL;
 292                 }
 293                 *header = *(struct ctdb_ltdb_header *)&r->data[r->keylen];
 294         }
 295
 296         return r;
 297 }
 298
 299 /**
 300  * CTDB transaction destructor
 301  */
 302 static int db_ctdb_transaction_destructor(struct db_ctdb_transaction_handle *h)
 303 {
 304         NTSTATUS status;
 305
 306         status = g_lock_unlock(h->ctx->lock_ctx, h->lock_name);
 307         if (!NT_STATUS_IS_OK(status)) {
 308                 DEBUG(0, ("g_lock_unlock failed: %s\n", nt_errstr(status)));
 309                 return -1;
 310         }
 311         return 0;
 312 }
 313
 314 /**
 315  * CTDB dbwrap API: transaction_start function
 316  * starts a transaction on a persistent database
 317  */
 318 static int db_ctdb_transaction_start(struct db_context *db)
 319 {
 320         struct db_ctdb_transaction_handle *h;
 321         NTSTATUS status;
 322         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 323                                                         struct db_ctdb_ctx);
 324
 325         if (!db->persistent) {
 326                 DEBUG(0,("transactions not supported on non-persistent database 0x%08x\n",
 327                          ctx->db_id));
 328                 return -1;
 329         }
 330
 331         if (ctx->transaction) {
 332                 ctx->transaction->nesting++;
 333                 return 0;
 334         }
 335
 336         h = talloc_zero(db, struct db_ctdb_transaction_handle);
 337         if (h == NULL) {
 338                 DEBUG(0,(__location__ " oom for transaction handle\n"));
 339                 return -1;
 340         }
 341
 342         h->ctx = ctx;
 343
 344         h->lock_name = talloc_asprintf(h, "transaction_db_0x%08x",
 345                                        (unsigned int)ctx->db_id);
 346         if (h->lock_name == NULL) {
 347                 DEBUG(0, ("talloc_asprintf failed\n"));
 348                 TALLOC_FREE(h);
 349                 return -1;
 350         }
 351
 352         /*
 353          * Wait a day, i.e. forever...
 354          */
 355         status = g_lock_lock(ctx->lock_ctx, h->lock_name, G_LOCK_WRITE,
 356                              timeval_set(86400, 0));
 357         if (!NT_STATUS_IS_OK(status)) {
 358                 DEBUG(0, ("g_lock_lock failed: %s\n", nt_errstr(status)));
 359                 TALLOC_FREE(h);
 360                 return -1;
 361         }
 362
 363         talloc_set_destructor(h, db_ctdb_transaction_destructor);
 364
 365         ctx->transaction = h;
 366
 367         DEBUG(5,(__location__ " Started transaction on db 0x%08x\n", ctx->db_id));
 368
 369         return 0;
 370 }
 371
 372 static bool pull_newest_from_marshall_buffer(struct ctdb_marshall_buffer *buf,
 373                                              TDB_DATA key,
 374                                              struct ctdb_ltdb_header *pheader,
 375                                              TALLOC_CTX *mem_ctx,
 376                                              TDB_DATA *pdata)
 377 {
 378         struct ctdb_rec_data *rec = NULL;
 379         struct ctdb_ltdb_header h;
 380         bool found = false;
 381         TDB_DATA data;
 382         int i;
 383
 384         if (buf == NULL) {
 385                 return false;
 386         }
 387
 388         ZERO_STRUCT(h);
 389         ZERO_STRUCT(data);
 390
 391         /*
 392          * Walk the list of records written during this
 393          * transaction. If we want to read one we have already
 394          * written, return the last written sample. Thus we do not do
 395          * a "break;" for the first hit, this record might have been
 396          * overwritten later.
 397          */
 398
 399         for (i=0; i<buf->count; i++) {
 400                 TDB_DATA tkey, tdata;
 401                 uint32_t reqid;
 402                 struct ctdb_ltdb_header hdr;
 403
 404                 ZERO_STRUCT(hdr);
 405
 406                 rec = db_ctdb_marshall_loop_next(buf, rec, &reqid, &hdr, &tkey,
 407                                                  &tdata);
 408                 if (rec == NULL) {
 409                         return false;
 410                 }
 411
 412                 if (tdb_data_equal(key, tkey)) {
 413                         found = true;
 414                         data = tdata;
 415                         h = hdr;
 416                 }
 417         }
 418
 419         if (!found) {
 420                 return false;
 421         }
 422
 423         if (pdata != NULL) {
 424                 data.dptr = (uint8_t *)talloc_memdup(mem_ctx, data.dptr,
 425                                                      data.dsize);
 426                 if ((data.dsize != 0) && (data.dptr == NULL)) {
 427                         return false;
 428                 }
 429                 *pdata = data;
 430         }
 431
 432         if (pheader != NULL) {
 433                 *pheader = h;
 434         }
 435
 436         return true;
 437 }
 438
 439 /*
 440   fetch a record inside a transaction
 441  */
 442 static int db_ctdb_transaction_fetch(struct db_ctdb_ctx *db,
 443                                      TALLOC_CTX *mem_ctx,
 444                                      TDB_DATA key, TDB_DATA *data)
 445 {
 446         struct db_ctdb_transaction_handle *h = db->transaction;
 447         NTSTATUS status;
 448         bool found;
 449
 450         found = pull_newest_from_marshall_buffer(h->m_write, key, NULL,
 451                                                  mem_ctx, data);
 452         if (found) {
 453                 return 0;
 454         }
 455
 456         status = db_ctdb_ltdb_fetch(h->ctx, key, NULL, mem_ctx, data);
 457
 458         if (NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND)) {
 459                 *data = tdb_null;
 460         } else if (!NT_STATUS_IS_OK(status)) {
 461                 return -1;
 462         }
 463
 464         h->m_all = db_ctdb_marshall_add(h, h->m_all, h->ctx->db_id, 1, key,
 465                                         NULL, *data);
 466         if (h->m_all == NULL) {
 467                 DEBUG(0,(__location__ " Failed to add to marshalling "
 468                          "record\n"));
 469                 data->dsize = 0;
 470                 talloc_free(data->dptr);
 471                 return -1;
 472         }
 473
 474         return 0;
 475 }
 476
 477 /**
 478  * Fetch a record from a persistent database
 479  * without record locking and without an active transaction.
 480  *
 481  * This just fetches from the local database copy.
 482  * Since the databases are kept in syc cluster-wide,
 483  * there is no point in doing a ctdb call to fetch the
 484  * record from the lmaster. It does even harm since migration
 485  * of records bump their RSN and hence render the persistent
 486  * database inconsistent.
 487  */
 488 static int db_ctdb_fetch_persistent(struct db_ctdb_ctx *db,
 489                                     TALLOC_CTX *mem_ctx,
 490                                     TDB_DATA key, TDB_DATA *data)
 491 {
 492         NTSTATUS status;
 493         bool found;
 494
 495         status = db_ctdb_ltdb_fetch(db, key, NULL, mem_ctx, data);
 496
 497         if (NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND)) {
 498                 *data = tdb_null;
 499         } else if (!NT_STATUS_IS_OK(status)) {
 500                 return -1;
 501         }
 502
 503         return 0;
 504 }
 505
 506 static NTSTATUS db_ctdb_store_transaction(struct db_record *rec, TDB_DATA data, int flag);
 507 static NTSTATUS db_ctdb_delete_transaction(struct db_record *rec);
 508
 509 static struct db_record *db_ctdb_fetch_locked_transaction(struct db_ctdb_ctx *ctx,
 510                                                           TALLOC_CTX *mem_ctx,
 511                                                           TDB_DATA key)
 512 {
 513         struct db_record *result;
 514         TDB_DATA ctdb_data;
 515
 516         if (!(result = talloc(mem_ctx, struct db_record))) {
 517                 DEBUG(0, ("talloc failed\n"));
 518                 return NULL;
 519         }
 520
 521         result->private_data = ctx->transaction;
 522
 523         result->key.dsize = key.dsize;
 524         result->key.dptr = (uint8 *)talloc_memdup(result, key.dptr, key.dsize);
 525         if (result->key.dptr == NULL) {
 526                 DEBUG(0, ("talloc failed\n"));
 527                 TALLOC_FREE(result);
 528                 return NULL;
 529         }
 530
 531         result->store = db_ctdb_store_transaction;
 532         result->delete_rec = db_ctdb_delete_transaction;
 533
 534         if (pull_newest_from_marshall_buffer(ctx->transaction->m_write, key,
 535                                              NULL, result, &result->value)) {
 536                 return result;
 537         }
 538
 539         ctdb_data = tdb_fetch(ctx->wtdb->tdb, key);
 540         if (ctdb_data.dptr == NULL) {
 541                 /* create the record */
 542                 result->value = tdb_null;
 543                 return result;
 544         }
 545
 546         result->value.dsize = ctdb_data.dsize - sizeof(struct ctdb_ltdb_header);
 547         result->value.dptr = NULL;
 548
 549         if ((result->value.dsize != 0)
 550             && !(result->value.dptr = (uint8 *)talloc_memdup(
 551                          result, ctdb_data.dptr + sizeof(struct ctdb_ltdb_header),
 552                          result->value.dsize))) {
 553                 DEBUG(0, ("talloc failed\n"));
 554                 TALLOC_FREE(result);
 555         }
 556
 557         SAFE_FREE(ctdb_data.dptr);
 558
 559         return result;
 560 }
 561
 562 static int db_ctdb_record_destructor(struct db_record **recp)
 563 {
 564         struct db_record *rec = talloc_get_type_abort(*recp, struct db_record);
 565         struct db_ctdb_transaction_handle *h = talloc_get_type_abort(
 566                 rec->private_data, struct db_ctdb_transaction_handle);
 567         int ret = h->ctx->db->transaction_commit(h->ctx->db);
 568         if (ret != 0) {
 569                 DEBUG(0,(__location__ " transaction_commit failed\n"));
 570         }
 571         return 0;
 572 }
 573
 574 /*
 575   auto-create a transaction for persistent databases
 576  */
 577 static struct db_record *db_ctdb_fetch_locked_persistent(struct db_ctdb_ctx *ctx,
 578                                                          TALLOC_CTX *mem_ctx,
 579                                                          TDB_DATA key)
 580 {
 581         int res;
 582         struct db_record *rec, **recp;
 583
 584         res = db_ctdb_transaction_start(ctx->db);
 585         if (res == -1) {
 586                 return NULL;
 587         }
 588
 589         rec = db_ctdb_fetch_locked_transaction(ctx, mem_ctx, key);
 590         if (rec == NULL) {
 591                 ctx->db->transaction_cancel(ctx->db);
 592                 return NULL;
 593         }
 594
 595         /* destroy this transaction when we release the lock */
 596         recp = talloc(rec, struct db_record *);
 597         if (recp == NULL) {
 598                 ctx->db->transaction_cancel(ctx->db);
 599                 talloc_free(rec);
 600                 return NULL;
 601         }
 602         *recp = rec;
 603         talloc_set_destructor(recp, db_ctdb_record_destructor);
 604         return rec;
 605 }
 606
 607
 608 /*
 609   stores a record inside a transaction
 610  */
 611 static NTSTATUS db_ctdb_transaction_store(struct db_ctdb_transaction_handle *h,
 612                                           TDB_DATA key, TDB_DATA data)
 613 {
 614         TALLOC_CTX *tmp_ctx = talloc_new(h);
 615         TDB_DATA rec;
 616         struct ctdb_ltdb_header header;
 617
 618         ZERO_STRUCT(header);
 619
 620         /* we need the header so we can update the RSN */
 621
 622         if (!pull_newest_from_marshall_buffer(h->m_write, key, &header,
 623                                               NULL, NULL)) {
 624
 625                 rec = tdb_fetch(h->ctx->wtdb->tdb, key);
 626
 627                 if (rec.dptr != NULL) {
 628                         memcpy(&header, rec.dptr,
 629                                sizeof(struct ctdb_ltdb_header));
 630                         rec.dsize -= sizeof(struct ctdb_ltdb_header);
 631
 632                         /*
 633                          * a special case, we are writing the same
 634                          * data that is there now
 635                          */
 636                         if (data.dsize == rec.dsize &&
 637                             memcmp(data.dptr,
 638                                    rec.dptr + sizeof(struct ctdb_ltdb_header),
 639                                    data.dsize) == 0) {
 640                                 SAFE_FREE(rec.dptr);
 641                                 talloc_free(tmp_ctx);
 642                                 return NT_STATUS_OK;
 643                         }
 644                 }
 645                 SAFE_FREE(rec.dptr);
 646         }
 647
 648         header.dmaster = get_my_vnn();
 649         header.rsn++;
 650
 651         h->m_all = db_ctdb_marshall_add(h, h->m_all, h->ctx->db_id, 0, key,
 652                                         NULL, data);
 653         if (h->m_all == NULL) {
 654                 DEBUG(0,(__location__ " Failed to add to marshalling "
 655                          "record\n"));
 656                 talloc_free(tmp_ctx);
 657                 return NT_STATUS_NO_MEMORY;
 658         }
 659
 660         h->m_write = db_ctdb_marshall_add(h, h->m_write, h->ctx->db_id, 0, key, &header, data);
 661         if (h->m_write == NULL) {
 662                 DEBUG(0,(__location__ " Failed to add to marshalling record\n"));
 663                 talloc_free(tmp_ctx);
 664                 return NT_STATUS_NO_MEMORY;
 665         }
 666
 667         talloc_free(tmp_ctx);
 668         return NT_STATUS_OK;
 669 }
 670
 671
 672 /*
 673    a record store inside a transaction
 674  */
 675 static NTSTATUS db_ctdb_store_transaction(struct db_record *rec, TDB_DATA data, int flag)
 676 {
 677         struct db_ctdb_transaction_handle *h = talloc_get_type_abort(
 678                 rec->private_data, struct db_ctdb_transaction_handle);
 679         NTSTATUS status;
 680
 681         status = db_ctdb_transaction_store(h, rec->key, data);
 682         return status;
 683 }
 684
 685 /*
 686    a record delete inside a transaction
 687  */
 688 static NTSTATUS db_ctdb_delete_transaction(struct db_record *rec)
 689 {
 690         struct db_ctdb_transaction_handle *h = talloc_get_type_abort(
 691                 rec->private_data, struct db_ctdb_transaction_handle);
 692         NTSTATUS status;
 693
 694         status =  db_ctdb_transaction_store(h, rec->key, tdb_null);
 695         return status;
 696 }
 697
 698 /**
 699  * Fetch the db sequence number of a persistent db directly from the db.
 700  */
 701 static NTSTATUS db_ctdb_fetch_db_seqnum_from_db(struct db_ctdb_ctx *db,
 702                                                 uint64_t *seqnum)
 703 {
 704         NTSTATUS status;
 705         const char *keyname = CTDB_DB_SEQNUM_KEY;
 706         TDB_DATA key;
 707         TDB_DATA data;
 708         struct ctdb_ltdb_header header;
 709         TALLOC_CTX *mem_ctx = talloc_stackframe();
 710
 711         if (seqnum == NULL) {
 712                 return NT_STATUS_INVALID_PARAMETER;
 713         }
 714
 715         key = string_term_tdb_data(keyname);
 716
 717         status = db_ctdb_ltdb_fetch(db, key, &header, mem_ctx, &data);
 718         if (!NT_STATUS_IS_OK(status) &&
 719             !NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND))
 720         {
 721                 goto done;
 722         }
 723
 724         status = NT_STATUS_OK;
 725
 726         if (data.dsize != sizeof(uint64_t)) {
 727                 *seqnum = 0;
 728                 goto done;
 729         }
 730
 731         *seqnum = *(uint64_t *)data.dptr;
 732
 733 done:
 734         TALLOC_FREE(mem_ctx);
 735         return status;
 736 }
 737
 738 /**
 739  * Store the database sequence number inside a transaction.
 740  */
 741 static NTSTATUS db_ctdb_store_db_seqnum(struct db_ctdb_transaction_handle *h,
 742                                         uint64_t seqnum)
 743 {
 744         NTSTATUS status;
 745         const char *keyname = CTDB_DB_SEQNUM_KEY;
 746         TDB_DATA key;
 747         TDB_DATA data;
 748
 749         key = string_term_tdb_data(keyname);
 750
 751         data.dptr = (uint8_t *)&seqnum;
 752         data.dsize = sizeof(uint64_t);
 753
 754         status = db_ctdb_transaction_store(h, key, data);
 755
 756         return status;
 757 }
 758
 759 /*
 760   commit a transaction
 761  */
 762 static int db_ctdb_transaction_commit(struct db_context *db)
 763 {
 764         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 765                                                         struct db_ctdb_ctx);
 766         NTSTATUS rets;
 767         int status;
 768         struct db_ctdb_transaction_handle *h = ctx->transaction;
 769         uint64_t old_seqnum, new_seqnum;
 770         int ret;
 771
 772         if (h == NULL) {
 773                 DEBUG(0,(__location__ " transaction commit with no open transaction on db 0x%08x\n", ctx->db_id));
 774                 return -1;
 775         }
 776
 777         if (h->nested_cancel) {
 778                 db->transaction_cancel(db);
 779                 DEBUG(5,(__location__ " Failed transaction commit after nested cancel\n"));
 780                 return -1;
 781         }
 782
 783         if (h->nesting != 0) {
 784                 h->nesting--;
 785                 return 0;
 786         }
 787
 788         if (h->m_write == NULL) {
 789                 /*
 790                  * No changes were made, so don't change the seqnum,
 791                  * don't push to other node, just exit with success.
 792                  */
 793                 ret = 0;
 794                 goto done;
 795         }
 796
 797         DEBUG(5,(__location__ " Commit transaction on db 0x%08x\n", ctx->db_id));
 798
 799         /*
 800          * As the last db action before committing, bump the database sequence
 801          * number. Note that this undoes all changes to the seqnum records
 802          * performed under the transaction. This record is not meant to be
 803          * modified by user interaction. It is for internal use only...
 804          */
 805         rets = db_ctdb_fetch_db_seqnum_from_db(ctx, &old_seqnum);
 806         if (!NT_STATUS_IS_OK(rets)) {
 807                 DEBUG(1, (__location__ " failed to fetch the db sequence number "
 808                           "in transaction commit on db 0x%08x\n", ctx->db_id));
 809                 ret = -1;
 810                 goto done;
 811         }
 812
 813         new_seqnum = old_seqnum + 1;
 814
 815         rets = db_ctdb_store_db_seqnum(h, new_seqnum);
 816         if (!NT_STATUS_IS_OK(rets)) {
 817                 DEBUG(1, (__location__ "failed to store the db sequence number "
 818                           " in transaction commit on db 0x%08x\n", ctx->db_id));
 819                 ret = -1;
 820                 goto done;
 821         }
 822
 823 again:
 824         /* tell ctdbd to commit to the other nodes */
 825         rets = ctdbd_control_local(messaging_ctdbd_connection(),
 826                                    CTDB_CONTROL_TRANS3_COMMIT,
 827                                    h->ctx->db_id, 0,
 828                                    db_ctdb_marshall_finish(h->m_write),
 829                                    NULL, NULL, &status);
 830         if (!NT_STATUS_IS_OK(rets) || status != 0) {
 831                 /*
 832                  * The TRANS3_COMMIT control should only possibly fail when a
 833                  * recovery has been running concurrently. In any case, the db
 834                  * will be the same on all nodes, either the new copy or the
 835                  * old copy.  This can be detected by comparing the old and new
 836                  * local sequence numbers.
 837                  */
 838                 rets = db_ctdb_fetch_db_seqnum_from_db(ctx, &new_seqnum);
 839                 if (!NT_STATUS_IS_OK(rets)) {
 840                         DEBUG(1, (__location__ " failed to refetch db sequence "
 841                                   "number after failed TRANS3_COMMIT\n"));
 842                         ret = -1;
 843                         goto done;
 844                 }
 845
 846                 if (new_seqnum == old_seqnum) {
 847                         /* Recovery prevented all our changes: retry. */
 848                         goto again;
 849                 } else if (new_seqnum != (old_seqnum + 1)) {
 850                         DEBUG(0, (__location__ " ERROR: new_seqnum[%lu] != "
 851                                   "old_seqnum[%lu] + (0 or 1) after failed "
 852                                   "TRANS3_COMMIT - this should not happen!\n",
 853                                   (unsigned long)new_seqnum,
 854                                   (unsigned long)old_seqnum));
 855                         ret = -1;
 856                         goto done;
 857                 }
 858                 /*
 859                  * Recovery propagated our changes to all nodes, completing
 860                  * our commit for us - succeed.
 861                  */
 862         }
 863
 864         ret = 0;
 865
 866 done:
 867         h->ctx->transaction = NULL;
 868         talloc_free(h);
 869         return ret;
 870 }
 871
 872
 873 /*
 874   cancel a transaction
 875  */
 876 static int db_ctdb_transaction_cancel(struct db_context *db)
 877 {
 878         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 879                                                         struct db_ctdb_ctx);
 880         struct db_ctdb_transaction_handle *h = ctx->transaction;
 881
 882         if (h == NULL) {
 883                 DEBUG(0,(__location__ " transaction cancel with no open transaction on db 0x%08x\n", ctx->db_id));
 884                 return -1;
 885         }
 886
 887         if (h->nesting != 0) {
 888                 h->nesting--;
 889                 h->nested_cancel = true;
 890                 return 0;
 891         }
 892
 893         DEBUG(5,(__location__ " Cancel transaction on db 0x%08x\n", ctx->db_id));
 894
 895         ctx->transaction = NULL;
 896         talloc_free(h);
 897         return 0;
 898 }
 899
 900
 901 static NTSTATUS db_ctdb_store(struct db_record *rec, TDB_DATA data, int flag)
 902 {
 903         struct db_ctdb_rec *crec = talloc_get_type_abort(
 904                 rec->private_data, struct db_ctdb_rec);
 905
 906         return db_ctdb_ltdb_store(crec->ctdb_ctx, rec->key, &(crec->header), data);
 907 }
 908
 909
 910
 911 #ifdef CTDB_CONTROL_SCHEDULE_FOR_DELETION
 912 static NTSTATUS db_ctdb_send_schedule_for_deletion(struct db_record *rec)
 913 {
 914         NTSTATUS status;
 915         struct ctdb_control_schedule_for_deletion *dd;
 916         TDB_DATA indata;
 917         int cstatus;
 918         struct db_ctdb_rec *crec = talloc_get_type_abort(
 919                 rec->private_data, struct db_ctdb_rec);
 920
 921         indata.dsize = offsetof(struct ctdb_control_schedule_for_deletion, key) + rec->key.dsize;
 922         indata.dptr = talloc_zero_array(crec, uint8_t, indata.dsize);
 923         if (indata.dptr == NULL) {
 924                 DEBUG(0, (__location__ " talloc failed!\n"));
 925                 return NT_STATUS_NO_MEMORY;
 926         }
 927
 928         dd = (struct ctdb_control_schedule_for_deletion *)(void *)indata.dptr;
 929         dd->db_id = crec->ctdb_ctx->db_id;
 930         dd->hdr = crec->header;
 931         dd->keylen = rec->key.dsize;
 932         memcpy(dd->key, rec->key.dptr, rec->key.dsize);
 933
 934         status = ctdbd_control_local(messaging_ctdbd_connection(),
 935                                      CTDB_CONTROL_SCHEDULE_FOR_DELETION,
 936                                      crec->ctdb_ctx->db_id,
 937                                      CTDB_CTRL_FLAG_NOREPLY, /* flags */
 938                                      indata,
 939                                      NULL, /* outdata */
 940                                      NULL, /* errmsg */
 941                                      &cstatus);
 942         talloc_free(indata.dptr);
 943
 944         if (!NT_STATUS_IS_OK(status) || cstatus != 0) {
 945                 DEBUG(1, (__location__ " Error sending local control "
 946                           "SCHEDULE_FOR_DELETION: %s, cstatus = %d\n",
 947                           nt_errstr(status), cstatus));
 948                 if (NT_STATUS_IS_OK(status)) {
 949                         status = NT_STATUS_UNSUCCESSFUL;
 950                 }
 951         }
 952
 953         return status;
 954 }
 955 #endif
 956
 957 static NTSTATUS db_ctdb_delete(struct db_record *rec)
 958 {
 959         TDB_DATA data;
 960         NTSTATUS status;
 961
 962         /*
 963          * We have to store the header with empty data. TODO: Fix the
 964          * tdb-level cleanup
 965          */
 966
 967         ZERO_STRUCT(data);
 968
 969         status = db_ctdb_store(rec, data, 0);
 970         if (!NT_STATUS_IS_OK(status)) {
 971                 return status;
 972         }
 973
 974 #ifdef CTDB_CONTROL_SCHEDULE_FOR_DELETION
 975         status = db_ctdb_send_schedule_for_deletion(rec);
 976 #endif
 977
 978         return status;
 979 }
 980
 981 static int db_ctdb_record_destr(struct db_record* data)
 982 {
 983         struct db_ctdb_rec *crec = talloc_get_type_abort(
 984                 data->private_data, struct db_ctdb_rec);
 985         int threshold;
 986
 987         DEBUG(10, (DEBUGLEVEL > 10
 988                    ? "Unlocking db %u key %s\n"
 989                    : "Unlocking db %u key %.20s\n",
 990                    (int)crec->ctdb_ctx->db_id,
 991                    hex_encode_talloc(data, (unsigned char *)data->key.dptr,
 992                               data->key.dsize)));
 993
 994         if (tdb_chainunlock(crec->ctdb_ctx->wtdb->tdb, data->key) != 0) {
 995                 DEBUG(0, ("tdb_chainunlock failed\n"));
 996                 return -1;
 997         }
 998
 999         threshold = lp_ctdb_locktime_warn_threshold();
1000         if (threshold != 0) {
1001                 double timediff = timeval_elapsed(&crec->lock_time);
1002                 if ((timediff * 1000) > threshold) {
1003                         DEBUG(0, ("Held tdb lock %f seconds\n", timediff));
1004                 }
1005         }
1006
1007         return 0;
1008 }
1009
1010 static struct db_record *fetch_locked_internal(struct db_ctdb_ctx *ctx,
1011                                                TALLOC_CTX *mem_ctx,
1012                                                TDB_DATA key)
1013 {
1014         struct db_record *result;
1015         struct db_ctdb_rec *crec;
1016         NTSTATUS status;
1017         TDB_DATA ctdb_data;
1018         int migrate_attempts = 0;
1019
1020         if (!(result = talloc(mem_ctx, struct db_record))) {
1021                 DEBUG(0, ("talloc failed\n"));
1022                 return NULL;
1023         }
1024
1025         if (!(crec = TALLOC_ZERO_P(result, struct db_ctdb_rec))) {
1026                 DEBUG(0, ("talloc failed\n"));
1027                 TALLOC_FREE(result);
1028                 return NULL;
1029         }
1030
1031         result->private_data = (void *)crec;
1032         crec->ctdb_ctx = ctx;
1033
1034         result->key.dsize = key.dsize;
1035         result->key.dptr = (uint8 *)talloc_memdup(result, key.dptr, key.dsize);
1036         if (result->key.dptr == NULL) {
1037                 DEBUG(0, ("talloc failed\n"));
1038                 TALLOC_FREE(result);
1039                 return NULL;
1040         }
1041
1042         /*
1043          * Do a blocking lock on the record
1044          */
1045 again:
1046
1047         if (DEBUGLEVEL >= 10) {
1048                 char *keystr = hex_encode_talloc(result, key.dptr, key.dsize);
1049                 DEBUG(10, (DEBUGLEVEL > 10
1050                            ? "Locking db %u key %s\n"
1051                            : "Locking db %u key %.20s\n",
1052                            (int)crec->ctdb_ctx->db_id, keystr));
1053                 TALLOC_FREE(keystr);
1054         }
1055
1056         if (tdb_chainlock(ctx->wtdb->tdb, key) != 0) {
1057                 DEBUG(3, ("tdb_chainlock failed\n"));
1058                 TALLOC_FREE(result);
1059                 return NULL;
1060         }
1061
1062         result->store = db_ctdb_store;
1063         result->delete_rec = db_ctdb_delete;
1064         talloc_set_destructor(result, db_ctdb_record_destr);
1065
1066         ctdb_data = tdb_fetch(ctx->wtdb->tdb, key);
1067
1068         /*
1069          * See if we have a valid record and we are the dmaster. If so, we can
1070          * take the shortcut and just return it.
1071          */
1072
1073         if ((ctdb_data.dptr == NULL) ||
1074             (ctdb_data.dsize < sizeof(struct ctdb_ltdb_header)) ||
1075             ((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster != get_my_vnn()
1076 #if 0
1077             || (random() % 2 != 0)
1078 #endif
1079 ) {
1080                 SAFE_FREE(ctdb_data.dptr);
1081                 tdb_chainunlock(ctx->wtdb->tdb, key);
1082                 talloc_set_destructor(result, NULL);
1083
1084                 migrate_attempts += 1;
1085
1086                 DEBUG(10, ("ctdb_data.dptr = %p, dmaster = %u (%u)\n",
1087                            ctdb_data.dptr, ctdb_data.dptr ?
1088                            ((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster : -1,
1089                            get_my_vnn()));
1090
1091                 status = ctdbd_migrate(messaging_ctdbd_connection(), ctx->db_id,
1092                                        key);
1093                 if (!NT_STATUS_IS_OK(status)) {
1094                         DEBUG(5, ("ctdb_migrate failed: %s\n",
1095                                   nt_errstr(status)));
1096                         TALLOC_FREE(result);
1097                         return NULL;
1098                 }
1099                 /* now its migrated, try again */
1100                 goto again;
1101         }
1102
1103         if (migrate_attempts > 10) {
1104                 DEBUG(0, ("db_ctdb_fetch_locked needed %d attempts\n",
1105                           migrate_attempts));
1106         }
1107
1108         GetTimeOfDay(&crec->lock_time);
1109
1110         memcpy(&crec->header, ctdb_data.dptr, sizeof(crec->header));
1111
1112         result->value.dsize = ctdb_data.dsize - sizeof(crec->header);
1113         result->value.dptr = NULL;
1114
1115         if ((result->value.dsize != 0)
1116             && !(result->value.dptr = (uint8 *)talloc_memdup(
1117                          result, ctdb_data.dptr + sizeof(crec->header),
1118                          result->value.dsize))) {
1119                 DEBUG(0, ("talloc failed\n"));
1120                 TALLOC_FREE(result);
1121         }
1122
1123         SAFE_FREE(ctdb_data.dptr);
1124
1125         return result;
1126 }
1127
1128 static struct db_record *db_ctdb_fetch_locked(struct db_context *db,
1129                                               TALLOC_CTX *mem_ctx,
1130                                               TDB_DATA key)
1131 {
1132         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1133                                                         struct db_ctdb_ctx);
1134
1135         if (ctx->transaction != NULL) {
1136                 return db_ctdb_fetch_locked_transaction(ctx, mem_ctx, key);
1137         }
1138
1139         if (db->persistent) {
1140                 return db_ctdb_fetch_locked_persistent(ctx, mem_ctx, key);
1141         }
1142
1143         return fetch_locked_internal(ctx, mem_ctx, key);
1144 }
1145
1146 /*
1147   fetch (unlocked, no migration) operation on ctdb
1148  */
1149 static int db_ctdb_fetch(struct db_context *db, TALLOC_CTX *mem_ctx,
1150                          TDB_DATA key, TDB_DATA *data)
1151 {
1152         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1153                                                         struct db_ctdb_ctx);
1154         NTSTATUS status;
1155         TDB_DATA ctdb_data;
1156
1157         if (ctx->transaction) {
1158                 return db_ctdb_transaction_fetch(ctx, mem_ctx, key, data);
1159         }
1160
1161         if (db->persistent) {
1162                 return db_ctdb_fetch_persistent(ctx, mem_ctx, key, data);
1163         }
1164
1165         /* try a direct fetch */
1166         ctdb_data = tdb_fetch(ctx->wtdb->tdb, key);
1167
1168         /*
1169          * See if we have a valid record and we are the dmaster. If so, we can
1170          * take the shortcut and just return it.
1171          * we bypass the dmaster check for persistent databases
1172          */
1173         if ((ctdb_data.dptr != NULL) &&
1174             (ctdb_data.dsize >= sizeof(struct ctdb_ltdb_header)) &&
1175             ((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster == get_my_vnn())
1176         {
1177                 /* we are the dmaster - avoid the ctdb protocol op */
1178
1179                 data->dsize = ctdb_data.dsize - sizeof(struct ctdb_ltdb_header);
1180                 if (data->dsize == 0) {
1181                         SAFE_FREE(ctdb_data.dptr);
1182                         data->dptr = NULL;
1183                         return 0;
1184                 }
1185
1186                 data->dptr = (uint8 *)talloc_memdup(
1187                         mem_ctx, ctdb_data.dptr+sizeof(struct ctdb_ltdb_header),
1188                         data->dsize);
1189
1190                 SAFE_FREE(ctdb_data.dptr);
1191
1192                 if (data->dptr == NULL) {
1193                         return -1;
1194                 }
1195                 return 0;
1196         }
1197
1198         SAFE_FREE(ctdb_data.dptr);
1199
1200         /* we weren't able to get it locally - ask ctdb to fetch it for us */
1201         status = ctdbd_fetch(messaging_ctdbd_connection(), ctx->db_id, key,
1202                              mem_ctx, data);
1203         if (!NT_STATUS_IS_OK(status)) {
1204                 DEBUG(5, ("ctdbd_fetch failed: %s\n", nt_errstr(status)));
1205                 return -1;
1206         }
1207
1208         return 0;
1209 }
1210
1211 struct traverse_state {
1212         struct db_context *db;
1213         int (*fn)(struct db_record *rec, void *private_data);
1214         void *private_data;
1215 };
1216
1217 static void traverse_callback(TDB_DATA key, TDB_DATA data, void *private_data)
1218 {
1219         struct traverse_state *state = (struct traverse_state *)private_data;
1220         struct db_record *rec;
1221         TALLOC_CTX *tmp_ctx = talloc_new(state->db);
1222         /* we have to give them a locked record to prevent races */
1223         rec = db_ctdb_fetch_locked(state->db, tmp_ctx, key);
1224         if (rec && rec->value.dsize > 0) {
1225                 state->fn(rec, state->private_data);
1226         }
1227         talloc_free(tmp_ctx);
1228 }
1229
1230 static int traverse_persistent_callback(TDB_CONTEXT *tdb, TDB_DATA kbuf, TDB_DATA dbuf,
1231                                         void *private_data)
1232 {
1233         struct traverse_state *state = (struct traverse_state *)private_data;
1234         struct db_record *rec;
1235         TALLOC_CTX *tmp_ctx = talloc_new(state->db);
1236         int ret = 0;
1237         /* we have to give them a locked record to prevent races */
1238         rec = db_ctdb_fetch_locked(state->db, tmp_ctx, kbuf);
1239         if (rec && rec->value.dsize > 0) {
1240                 ret = state->fn(rec, state->private_data);
1241         }
1242         talloc_free(tmp_ctx);
1243         return ret;
1244 }
1245
1246 static int db_ctdb_traverse(struct db_context *db,
1247                             int (*fn)(struct db_record *rec,
1248                                       void *private_data),
1249                             void *private_data)
1250 {
1251         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1252                                                         struct db_ctdb_ctx);
1253         struct traverse_state state;
1254
1255         state.db = db;
1256         state.fn = fn;
1257         state.private_data = private_data;
1258
1259         if (db->persistent) {
1260                 /* for persistent databases we don't need to do a ctdb traverse,
1261                    we can do a faster local traverse */
1262                 return tdb_traverse(ctx->wtdb->tdb, traverse_persistent_callback, &state);
1263         }
1264
1265
1266         ctdbd_traverse(ctx->db_id, traverse_callback, &state);
1267         return 0;
1268 }
1269
1270 static NTSTATUS db_ctdb_store_deny(struct db_record *rec, TDB_DATA data, int flag)
1271 {
1272         return NT_STATUS_MEDIA_WRITE_PROTECTED;
1273 }
1274
1275 static NTSTATUS db_ctdb_delete_deny(struct db_record *rec)
1276 {
1277         return NT_STATUS_MEDIA_WRITE_PROTECTED;
1278 }
1279
1280 static void traverse_read_callback(TDB_DATA key, TDB_DATA data, void *private_data)
1281 {
1282         struct traverse_state *state = (struct traverse_state *)private_data;
1283         struct db_record rec;
1284         rec.key = key;
1285         rec.value = data;
1286         rec.store = db_ctdb_store_deny;
1287         rec.delete_rec = db_ctdb_delete_deny;
1288         rec.private_data = state->db;
1289         state->fn(&rec, state->private_data);
1290 }
1291
1292 static int traverse_persistent_callback_read(TDB_CONTEXT *tdb, TDB_DATA kbuf, TDB_DATA dbuf,
1293                                         void *private_data)
1294 {
1295         struct traverse_state *state = (struct traverse_state *)private_data;
1296         struct db_record rec;
1297         rec.key = kbuf;
1298         rec.value = dbuf;
1299         rec.store = db_ctdb_store_deny;
1300         rec.delete_rec = db_ctdb_delete_deny;
1301         rec.private_data = state->db;
1302
1303         if (rec.value.dsize <= sizeof(struct ctdb_ltdb_header)) {
1304                 /* a deleted record */
1305                 return 0;
1306         }
1307         rec.value.dsize -= sizeof(struct ctdb_ltdb_header);
1308         rec.value.dptr += sizeof(struct ctdb_ltdb_header);
1309
1310         return state->fn(&rec, state->private_data);
1311 }
1312
1313 static int db_ctdb_traverse_read(struct db_context *db,
1314                                  int (*fn)(struct db_record *rec,
1315                                            void *private_data),
1316                                  void *private_data)
1317 {
1318         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1319                                                         struct db_ctdb_ctx);
1320         struct traverse_state state;
1321
1322         state.db = db;
1323         state.fn = fn;
1324         state.private_data = private_data;
1325
1326         if (db->persistent) {
1327                 /* for persistent databases we don't need to do a ctdb traverse,
1328                    we can do a faster local traverse */
1329                 return tdb_traverse_read(ctx->wtdb->tdb, traverse_persistent_callback_read, &state);
1330         }
1331
1332         ctdbd_traverse(ctx->db_id, traverse_read_callback, &state);
1333         return 0;
1334 }
1335
1336 static int db_ctdb_get_seqnum(struct db_context *db)
1337 {
1338         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1339                                                         struct db_ctdb_ctx);
1340         return tdb_get_seqnum(ctx->wtdb->tdb);
1341 }
1342
1343 static int db_ctdb_get_flags(struct db_context *db)
1344 {
1345         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1346                                                         struct db_ctdb_ctx);
1347         return tdb_get_flags(ctx->wtdb->tdb);
1348 }
1349
1350 struct db_context *db_open_ctdb(TALLOC_CTX *mem_ctx,
1351                                 const char *name,
1352                                 int hash_size, int tdb_flags,
1353                                 int open_flags, mode_t mode)
1354 {
1355         struct db_context *result;
1356         struct db_ctdb_ctx *db_ctdb;
1357         char *db_path;
1358         struct ctdbd_connection *conn;
1359
1360         if (!lp_clustering()) {
1361                 DEBUG(10, ("Clustering disabled -- no ctdb\n"));
1362                 return NULL;
1363         }
1364
1365         if (!(result = TALLOC_ZERO_P(mem_ctx, struct db_context))) {
1366                 DEBUG(0, ("talloc failed\n"));
1367                 TALLOC_FREE(result);
1368                 return NULL;
1369         }
1370
1371         if (!(db_ctdb = TALLOC_P(result, struct db_ctdb_ctx))) {
1372                 DEBUG(0, ("talloc failed\n"));
1373                 TALLOC_FREE(result);
1374                 return NULL;
1375         }
1376
1377         db_ctdb->transaction = NULL;
1378         db_ctdb->db = result;
1379
1380         conn = messaging_ctdbd_connection();
1381         if (conn == NULL) {
1382                 DEBUG(1, ("Could not connect to ctdb\n"));
1383                 TALLOC_FREE(result);
1384                 return NULL;
1385         }
1386
1387         if (!NT_STATUS_IS_OK(ctdbd_db_attach(conn, name, &db_ctdb->db_id, tdb_flags))) {
1388                 DEBUG(0, ("ctdbd_db_attach failed for %s\n", name));
1389                 TALLOC_FREE(result);
1390                 return NULL;
1391         }
1392
1393         db_path = ctdbd_dbpath(conn, db_ctdb, db_ctdb->db_id);
1394
1395         result->persistent = ((tdb_flags & TDB_CLEAR_IF_FIRST) == 0);
1396
1397         /* only pass through specific flags */
1398         tdb_flags &= TDB_SEQNUM;
1399
1400         /* honor permissions if user has specified O_CREAT */
1401         if (open_flags & O_CREAT) {
1402                 chmod(db_path, mode);
1403         }
1404
1405         db_ctdb->wtdb = tdb_wrap_open(db_ctdb, db_path, hash_size, tdb_flags, O_RDWR, 0);
1406         if (db_ctdb->wtdb == NULL) {
1407                 DEBUG(0, ("Could not open tdb %s: %s\n", db_path, strerror(errno)));
1408                 TALLOC_FREE(result);
1409                 return NULL;
1410         }
1411         talloc_free(db_path);
1412
1413         if (result->persistent) {
1414                 db_ctdb->lock_ctx = g_lock_ctx_init(db_ctdb,
1415                                                     ctdb_conn_msg_ctx(conn));
1416                 if (db_ctdb->lock_ctx == NULL) {
1417                         DEBUG(0, ("g_lock_ctx_init failed\n"));
1418                         TALLOC_FREE(result);
1419                         return NULL;
1420                 }
1421         }
1422
1423         result->private_data = (void *)db_ctdb;
1424         result->fetch_locked = db_ctdb_fetch_locked;
1425         result->fetch = db_ctdb_fetch;
1426         result->traverse = db_ctdb_traverse;
1427         result->traverse_read = db_ctdb_traverse_read;
1428         result->get_seqnum = db_ctdb_get_seqnum;
1429         result->get_flags = db_ctdb_get_flags;
1430         result->transaction_start = db_ctdb_transaction_start;
1431         result->transaction_commit = db_ctdb_transaction_commit;
1432         result->transaction_cancel = db_ctdb_transaction_cancel;
1433
1434         DEBUG(3,("db_open_ctdb: opened database '%s' with dbid 0x%x\n",
1435                  name, db_ctdb->db_id));
1436
1437         return result;
1438 }
1439 #endif