source3/lib/dbwrap/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 #include "system/filesys.h"
  23 #include "lib/tdb_wrap/tdb_wrap.h"
  24 #include "util_tdb.h"
  25 #include "dbwrap/dbwrap.h"
  26 #include "dbwrap/dbwrap_ctdb.h"
  27 #include "dbwrap/dbwrap_rbt.h"
  28 #include "lib/param/param.h"
  29
  30 #ifdef CLUSTER_SUPPORT
  31
  32 /*
  33  * It is not possible to include ctdb.h and tdb_compat.h (included via
  34  * some other include above) without warnings. This fixes those
  35  * warnings.
  36  */
  37
  38 #ifdef typesafe_cb
  39 #undef typesafe_cb
  40 #endif
  41
  42 #ifdef typesafe_cb_preargs
  43 #undef typesafe_cb_preargs
  44 #endif
  45
  46 #ifdef typesafe_cb_postargs
  47 #undef typesafe_cb_postargs
  48 #endif
  49
  50 #include "ctdb.h"
  51 #include "ctdb_private.h"
  52 #include "ctdbd_conn.h"
  53 #include "dbwrap/dbwrap.h"
  54 #include "dbwrap/dbwrap_private.h"
  55 #include "dbwrap/dbwrap_ctdb.h"
  56 #include "g_lock.h"
  57 #include "messages.h"
  58
  59 struct db_ctdb_transaction_handle {
  60         struct db_ctdb_ctx *ctx;
  61         /*
  62          * we store the writes done under a transaction:
  63          */
  64         struct ctdb_marshall_buffer *m_write;
  65         uint32_t nesting;
  66         bool nested_cancel;
  67         char *lock_name;
  68 };
  69
  70 struct db_ctdb_ctx {
  71         struct db_context *db;
  72         struct tdb_wrap *wtdb;
  73         uint32_t db_id;
  74         struct db_ctdb_transaction_handle *transaction;
  75         struct g_lock_ctx *lock_ctx;
  76
  77         /* thresholds for warning messages */
  78         int warn_unlock_msecs;
  79         int warn_migrate_msecs;
  80         int warn_migrate_attempts;
  81         int warn_locktime_msecs;
  82 };
  83
  84 struct db_ctdb_rec {
  85         struct db_ctdb_ctx *ctdb_ctx;
  86         struct ctdb_ltdb_header header;
  87         struct timeval lock_time;
  88 };
  89
  90 static NTSTATUS tdb_error_to_ntstatus(struct tdb_context *tdb)
  91 {
  92         enum TDB_ERROR tret = tdb_error(tdb);
  93
  94         return map_nt_error_from_tdb(tret);
  95 }
  96
  97 struct db_ctdb_ltdb_parse_state {
  98         void (*parser)(TDB_DATA key, struct ctdb_ltdb_header *header,
  99                        TDB_DATA data, void *private_data);
 100         void *private_data;
 101 };
 102
 103 static int db_ctdb_ltdb_parser(TDB_DATA key, TDB_DATA data,
 104                                void *private_data)
 105 {
 106         struct db_ctdb_ltdb_parse_state *state =
 107                 (struct db_ctdb_ltdb_parse_state *)private_data;
 108
 109         if (data.dsize < sizeof(struct ctdb_ltdb_header)) {
 110                 return -1;
 111         }
 112         if (data.dsize == sizeof(struct ctdb_ltdb_header)) {
 113                 /*
 114                  * Making this a separate case that needs fixing
 115                  * separately. This is an empty record. ctdbd does not
 116                  * distinguish between empty and deleted records. Samba right
 117                  * now can live without empty records, so lets treat zero-size
 118                  * (i.e. deleted) records as non-existing.
 119                  */
 120                 return -1;
 121         }
 122         state->parser(
 123                 key, (struct ctdb_ltdb_header *)data.dptr,
 124                 make_tdb_data(data.dptr + sizeof(struct ctdb_ltdb_header),
 125                               data.dsize - sizeof(struct ctdb_ltdb_header)),
 126                 state->private_data);
 127         return 0;
 128 }
 129
 130 static NTSTATUS db_ctdb_ltdb_parse(
 131         struct db_ctdb_ctx *db, TDB_DATA key,
 132         void (*parser)(TDB_DATA key, struct ctdb_ltdb_header *header,
 133                        TDB_DATA data, void *private_data),
 134         void *private_data)
 135 {
 136         struct db_ctdb_ltdb_parse_state state;
 137         int ret;
 138
 139         state.parser = parser;
 140         state.private_data = private_data;
 141
 142         ret = tdb_parse_record(db->wtdb->tdb, key, db_ctdb_ltdb_parser,
 143                                &state);
 144         if (ret == -1) {
 145                 return NT_STATUS_NOT_FOUND;
 146         }
 147         return NT_STATUS_OK;
 148 }
 149
 150 /*
 151  * Store a record together with the ctdb record header
 152  * in the local copy of the database.
 153  */
 154 static NTSTATUS db_ctdb_ltdb_store(struct db_ctdb_ctx *db,
 155                                    TDB_DATA key,
 156                                    struct ctdb_ltdb_header *header,
 157                                    TDB_DATA data)
 158 {
 159         TDB_DATA rec;
 160         int ret;
 161
 162         rec.dsize = data.dsize + sizeof(struct ctdb_ltdb_header);
 163         rec.dptr = (uint8_t *)talloc_size(talloc_tos(), rec.dsize);
 164
 165         if (rec.dptr == NULL) {
 166                 return NT_STATUS_NO_MEMORY;
 167         }
 168
 169         memcpy(rec.dptr, header, sizeof(struct ctdb_ltdb_header));
 170         memcpy(sizeof(struct ctdb_ltdb_header) + (uint8_t *)rec.dptr, data.dptr, data.dsize);
 171
 172         ret = tdb_store(db->wtdb->tdb, key, rec, TDB_REPLACE);
 173
 174         talloc_free(rec.dptr);
 175
 176         return (ret == 0) ? NT_STATUS_OK
 177                           : tdb_error_to_ntstatus(db->wtdb->tdb);
 178
 179 }
 180
 181 /*
 182   form a ctdb_rec_data record from a key/data pair
 183  */
 184 static struct ctdb_rec_data *db_ctdb_marshall_record(TALLOC_CTX *mem_ctx, uint32_t reqid,
 185                                                   TDB_DATA key,
 186                                                   struct ctdb_ltdb_header *header,
 187                                                   TDB_DATA data)
 188 {
 189         size_t length;
 190         struct ctdb_rec_data *d;
 191
 192         length = offsetof(struct ctdb_rec_data, data) + key.dsize +
 193                 data.dsize + sizeof(*header);
 194         d = (struct ctdb_rec_data *)talloc_size(mem_ctx, length);
 195         if (d == NULL) {
 196                 return NULL;
 197         }
 198         d->length = length;
 199         d->reqid = reqid;
 200         d->keylen = key.dsize;
 201         memcpy(&d->data[0], key.dptr, key.dsize);
 202
 203         d->datalen = data.dsize + sizeof(*header);
 204         memcpy(&d->data[key.dsize], header, sizeof(*header));
 205         memcpy(&d->data[key.dsize+sizeof(*header)], data.dptr, data.dsize);
 206         return d;
 207 }
 208
 209
 210 /* helper function for marshalling multiple records */
 211 static struct ctdb_marshall_buffer *db_ctdb_marshall_add(TALLOC_CTX *mem_ctx,
 212                                                struct ctdb_marshall_buffer *m,
 213                                                uint64_t db_id,
 214                                                uint32_t reqid,
 215                                                TDB_DATA key,
 216                                                struct ctdb_ltdb_header *header,
 217                                                TDB_DATA data)
 218 {
 219         struct ctdb_rec_data *r;
 220         size_t m_size, r_size;
 221         struct ctdb_marshall_buffer *m2 = NULL;
 222
 223         r = db_ctdb_marshall_record(talloc_tos(), reqid, key, header, data);
 224         if (r == NULL) {
 225                 talloc_free(m);
 226                 return NULL;
 227         }
 228
 229         if (m == NULL) {
 230                 m = (struct ctdb_marshall_buffer *)talloc_zero_size(
 231                         mem_ctx, offsetof(struct ctdb_marshall_buffer, data));
 232                 if (m == NULL) {
 233                         goto done;
 234                 }
 235                 m->db_id = db_id;
 236         }
 237
 238         m_size = talloc_get_size(m);
 239         r_size = talloc_get_size(r);
 240
 241         m2 = (struct ctdb_marshall_buffer *)talloc_realloc_size(
 242                 mem_ctx, m,  m_size + r_size);
 243         if (m2 == NULL) {
 244                 talloc_free(m);
 245                 goto done;
 246         }
 247
 248         memcpy(m_size + (uint8_t *)m2, r, r_size);
 249
 250         m2->count++;
 251
 252 done:
 253         talloc_free(r);
 254         return m2;
 255 }
 256
 257 /* we've finished marshalling, return a data blob with the marshalled records */
 258 static TDB_DATA db_ctdb_marshall_finish(struct ctdb_marshall_buffer *m)
 259 {
 260         TDB_DATA data;
 261         data.dptr = (uint8_t *)m;
 262         data.dsize = talloc_get_size(m);
 263         return data;
 264 }
 265
 266 /*
 267    loop over a marshalling buffer
 268
 269      - pass r==NULL to start
 270      - loop the number of times indicated by m->count
 271 */
 272 static struct ctdb_rec_data *db_ctdb_marshall_loop_next_key(
 273         struct ctdb_marshall_buffer *m, struct ctdb_rec_data *r, TDB_DATA *key)
 274 {
 275         if (r == NULL) {
 276                 r = (struct ctdb_rec_data *)&m->data[0];
 277         } else {
 278                 r = (struct ctdb_rec_data *)(r->length + (uint8_t *)r);
 279         }
 280
 281         key->dptr   = &r->data[0];
 282         key->dsize  = r->keylen;
 283         return r;
 284 }
 285
 286 static bool db_ctdb_marshall_buf_parse(
 287         struct ctdb_rec_data *r, uint32_t *reqid,
 288         struct ctdb_ltdb_header **header, TDB_DATA *data)
 289 {
 290         if (r->datalen < sizeof(struct ctdb_ltdb_header)) {
 291                 return false;
 292         }
 293
 294         *reqid = r->reqid;
 295
 296         data->dptr  = &r->data[r->keylen] + sizeof(struct ctdb_ltdb_header);
 297         data->dsize = r->datalen - sizeof(struct ctdb_ltdb_header);
 298
 299         *header = (struct ctdb_ltdb_header *)&r->data[r->keylen];
 300
 301         return true;
 302 }
 303
 304 /**
 305  * CTDB transaction destructor
 306  */
 307 static int db_ctdb_transaction_destructor(struct db_ctdb_transaction_handle *h)
 308 {
 309         NTSTATUS status;
 310
 311         status = g_lock_unlock(h->ctx->lock_ctx, h->lock_name);
 312         if (!NT_STATUS_IS_OK(status)) {
 313                 DEBUG(0, ("g_lock_unlock failed for %s: %s\n", h->lock_name,
 314                           nt_errstr(status)));
 315                 return -1;
 316         }
 317         return 0;
 318 }
 319
 320 /**
 321  * CTDB dbwrap API: transaction_start function
 322  * starts a transaction on a persistent database
 323  */
 324 static int db_ctdb_transaction_start(struct db_context *db)
 325 {
 326         struct db_ctdb_transaction_handle *h;
 327         NTSTATUS status;
 328         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 329                                                         struct db_ctdb_ctx);
 330
 331         if (!db->persistent) {
 332                 DEBUG(0,("transactions not supported on non-persistent database 0x%08x\n",
 333                          ctx->db_id));
 334                 return -1;
 335         }
 336
 337         if (ctx->transaction) {
 338                 ctx->transaction->nesting++;
 339                 DEBUG(5, (__location__ " transaction start on db 0x%08x: nesting %d -> %d\n",
 340                           ctx->db_id, ctx->transaction->nesting - 1, ctx->transaction->nesting));
 341                 return 0;
 342         }
 343
 344         h = talloc_zero(db, struct db_ctdb_transaction_handle);
 345         if (h == NULL) {
 346                 DEBUG(0,(__location__ " oom for transaction handle\n"));
 347                 return -1;
 348         }
 349
 350         h->ctx = ctx;
 351
 352         h->lock_name = talloc_asprintf(h, "transaction_db_0x%08x",
 353                                        (unsigned int)ctx->db_id);
 354         if (h->lock_name == NULL) {
 355                 DEBUG(0, ("talloc_asprintf failed\n"));
 356                 TALLOC_FREE(h);
 357                 return -1;
 358         }
 359
 360         /*
 361          * Wait a day, i.e. forever...
 362          */
 363         status = g_lock_lock(ctx->lock_ctx, h->lock_name, G_LOCK_WRITE,
 364                              timeval_set(86400, 0));
 365         if (!NT_STATUS_IS_OK(status)) {
 366                 DEBUG(0, ("g_lock_lock failed: %s\n", nt_errstr(status)));
 367                 TALLOC_FREE(h);
 368                 return -1;
 369         }
 370
 371         talloc_set_destructor(h, db_ctdb_transaction_destructor);
 372
 373         ctx->transaction = h;
 374
 375         DEBUG(5,(__location__ " transaction started on db 0x%08x\n", ctx->db_id));
 376
 377         return 0;
 378 }
 379
 380 static bool parse_newest_in_marshall_buffer(
 381         struct ctdb_marshall_buffer *buf, TDB_DATA key,
 382         void (*parser)(TDB_DATA key, struct ctdb_ltdb_header *header,
 383                        TDB_DATA data, void *private_data),
 384         void *private_data)
 385 {
 386         struct ctdb_rec_data *rec = NULL;
 387         struct ctdb_ltdb_header *h = NULL;
 388         TDB_DATA data;
 389         int i;
 390
 391         if (buf == NULL) {
 392                 return false;
 393         }
 394
 395         /*
 396          * Walk the list of records written during this
 397          * transaction. If we want to read one we have already
 398          * written, return the last written sample. Thus we do not do
 399          * a "break;" for the first hit, this record might have been
 400          * overwritten later.
 401          */
 402
 403         for (i=0; i<buf->count; i++) {
 404                 TDB_DATA tkey;
 405                 uint32_t reqid;
 406
 407                 rec = db_ctdb_marshall_loop_next_key(buf, rec, &tkey);
 408                 if (rec == NULL) {
 409                         return false;
 410                 }
 411
 412                 if (!tdb_data_equal(key, tkey)) {
 413                         continue;
 414                 }
 415
 416                 if (!db_ctdb_marshall_buf_parse(rec, &reqid, &h, &data)) {
 417                         return false;
 418                 }
 419         }
 420
 421         if (h == NULL) {
 422                 return false;
 423         }
 424
 425         parser(key, h, data, private_data);
 426
 427         return true;
 428 }
 429
 430 struct pull_newest_from_marshall_buffer_state {
 431         struct ctdb_ltdb_header *pheader;
 432         TALLOC_CTX *mem_ctx;
 433         TDB_DATA *pdata;
 434 };
 435
 436 static void pull_newest_from_marshall_buffer_parser(
 437         TDB_DATA key, struct ctdb_ltdb_header *header,
 438         TDB_DATA data, void *private_data)
 439 {
 440         struct pull_newest_from_marshall_buffer_state *state =
 441                 (struct pull_newest_from_marshall_buffer_state *)private_data;
 442
 443         if (state->pheader != NULL) {
 444                 memcpy(state->pheader, header, sizeof(*state->pheader));
 445         }
 446         if (state->pdata != NULL) {
 447                 state->pdata->dsize = data.dsize;
 448                 state->pdata->dptr = (uint8_t *)talloc_memdup(
 449                         state->mem_ctx, data.dptr, data.dsize);
 450         }
 451 }
 452
 453 static bool pull_newest_from_marshall_buffer(struct ctdb_marshall_buffer *buf,
 454                                              TDB_DATA key,
 455                                              struct ctdb_ltdb_header *pheader,
 456                                              TALLOC_CTX *mem_ctx,
 457                                              TDB_DATA *pdata)
 458 {
 459         struct pull_newest_from_marshall_buffer_state state;
 460
 461         state.pheader = pheader;
 462         state.mem_ctx = mem_ctx;
 463         state.pdata = pdata;
 464
 465         if (!parse_newest_in_marshall_buffer(
 466                     buf, key, pull_newest_from_marshall_buffer_parser,
 467                     &state)) {
 468                 return false;
 469         }
 470         if ((pdata != NULL) && (pdata->dsize != 0) && (pdata->dptr == NULL)) {
 471                 /* ENOMEM */
 472                 return false;
 473         }
 474         return true;
 475 }
 476
 477 static NTSTATUS db_ctdb_store_transaction(struct db_record *rec, TDB_DATA data, int flag);
 478 static NTSTATUS db_ctdb_delete_transaction(struct db_record *rec);
 479
 480 static struct db_record *db_ctdb_fetch_locked_transaction(struct db_ctdb_ctx *ctx,
 481                                                           TALLOC_CTX *mem_ctx,
 482                                                           TDB_DATA key)
 483 {
 484         struct db_record *result;
 485         TDB_DATA ctdb_data;
 486
 487         if (!(result = talloc(mem_ctx, struct db_record))) {
 488                 DEBUG(0, ("talloc failed\n"));
 489                 return NULL;
 490         }
 491
 492         result->db = ctx->db;
 493         result->private_data = ctx->transaction;
 494
 495         result->key.dsize = key.dsize;
 496         result->key.dptr = (uint8_t *)talloc_memdup(result, key.dptr,
 497                                                     key.dsize);
 498         if (result->key.dptr == NULL) {
 499                 DEBUG(0, ("talloc failed\n"));
 500                 TALLOC_FREE(result);
 501                 return NULL;
 502         }
 503
 504         result->store = db_ctdb_store_transaction;
 505         result->delete_rec = db_ctdb_delete_transaction;
 506
 507         if (pull_newest_from_marshall_buffer(ctx->transaction->m_write, key,
 508                                              NULL, result, &result->value)) {
 509                 return result;
 510         }
 511
 512         ctdb_data = tdb_fetch_compat(ctx->wtdb->tdb, key);
 513         if (ctdb_data.dptr == NULL) {
 514                 /* create the record */
 515                 result->value = tdb_null;
 516                 return result;
 517         }
 518
 519         result->value.dsize = ctdb_data.dsize - sizeof(struct ctdb_ltdb_header);
 520         result->value.dptr = NULL;
 521
 522         if ((result->value.dsize != 0)
 523             && !(result->value.dptr = (uint8_t *)talloc_memdup(
 524                          result, ctdb_data.dptr + sizeof(struct ctdb_ltdb_header),
 525                          result->value.dsize))) {
 526                 DEBUG(0, ("talloc failed\n"));
 527                 TALLOC_FREE(result);
 528         }
 529
 530         SAFE_FREE(ctdb_data.dptr);
 531
 532         return result;
 533 }
 534
 535 static int db_ctdb_record_destructor(struct db_record **recp)
 536 {
 537         struct db_record *rec = talloc_get_type_abort(*recp, struct db_record);
 538         struct db_ctdb_transaction_handle *h = talloc_get_type_abort(
 539                 rec->private_data, struct db_ctdb_transaction_handle);
 540         int ret = h->ctx->db->transaction_commit(h->ctx->db);
 541         if (ret != 0) {
 542                 DEBUG(0,(__location__ " transaction_commit failed\n"));
 543         }
 544         return 0;
 545 }
 546
 547 /*
 548   auto-create a transaction for persistent databases
 549  */
 550 static struct db_record *db_ctdb_fetch_locked_persistent(struct db_ctdb_ctx *ctx,
 551                                                          TALLOC_CTX *mem_ctx,
 552                                                          TDB_DATA key)
 553 {
 554         int res;
 555         struct db_record *rec, **recp;
 556
 557         res = db_ctdb_transaction_start(ctx->db);
 558         if (res == -1) {
 559                 return NULL;
 560         }
 561
 562         rec = db_ctdb_fetch_locked_transaction(ctx, mem_ctx, key);
 563         if (rec == NULL) {
 564                 ctx->db->transaction_cancel(ctx->db);
 565                 return NULL;
 566         }
 567
 568         /* destroy this transaction when we release the lock */
 569         recp = talloc(rec, struct db_record *);
 570         if (recp == NULL) {
 571                 ctx->db->transaction_cancel(ctx->db);
 572                 talloc_free(rec);
 573                 return NULL;
 574         }
 575         *recp = rec;
 576         talloc_set_destructor(recp, db_ctdb_record_destructor);
 577         return rec;
 578 }
 579
 580
 581 /*
 582   stores a record inside a transaction
 583  */
 584 static NTSTATUS db_ctdb_transaction_store(struct db_ctdb_transaction_handle *h,
 585                                           TDB_DATA key, TDB_DATA data)
 586 {
 587         TALLOC_CTX *tmp_ctx = talloc_new(h);
 588         TDB_DATA rec;
 589         struct ctdb_ltdb_header header;
 590
 591         ZERO_STRUCT(header);
 592
 593         /* we need the header so we can update the RSN */
 594
 595         if (!pull_newest_from_marshall_buffer(h->m_write, key, &header,
 596                                               NULL, NULL)) {
 597
 598                 rec = tdb_fetch_compat(h->ctx->wtdb->tdb, key);
 599
 600                 if (rec.dptr != NULL) {
 601                         memcpy(&header, rec.dptr,
 602                                sizeof(struct ctdb_ltdb_header));
 603                         rec.dsize -= sizeof(struct ctdb_ltdb_header);
 604
 605                         /*
 606                          * a special case, we are writing the same
 607                          * data that is there now
 608                          */
 609                         if (data.dsize == rec.dsize &&
 610                             memcmp(data.dptr,
 611                                    rec.dptr + sizeof(struct ctdb_ltdb_header),
 612                                    data.dsize) == 0) {
 613                                 SAFE_FREE(rec.dptr);
 614                                 talloc_free(tmp_ctx);
 615                                 return NT_STATUS_OK;
 616                         }
 617                 }
 618                 SAFE_FREE(rec.dptr);
 619         }
 620
 621         header.dmaster = get_my_vnn();
 622         header.rsn++;
 623
 624         h->m_write = db_ctdb_marshall_add(h, h->m_write, h->ctx->db_id, 0, key, &header, data);
 625         if (h->m_write == NULL) {
 626                 DEBUG(0,(__location__ " Failed to add to marshalling record\n"));
 627                 talloc_free(tmp_ctx);
 628                 return NT_STATUS_NO_MEMORY;
 629         }
 630
 631         talloc_free(tmp_ctx);
 632         return NT_STATUS_OK;
 633 }
 634
 635
 636 /*
 637    a record store inside a transaction
 638  */
 639 static NTSTATUS db_ctdb_store_transaction(struct db_record *rec, TDB_DATA data, int flag)
 640 {
 641         struct db_ctdb_transaction_handle *h = talloc_get_type_abort(
 642                 rec->private_data, struct db_ctdb_transaction_handle);
 643         NTSTATUS status;
 644
 645         status = db_ctdb_transaction_store(h, rec->key, data);
 646         return status;
 647 }
 648
 649 /*
 650    a record delete inside a transaction
 651  */
 652 static NTSTATUS db_ctdb_delete_transaction(struct db_record *rec)
 653 {
 654         struct db_ctdb_transaction_handle *h = talloc_get_type_abort(
 655                 rec->private_data, struct db_ctdb_transaction_handle);
 656         NTSTATUS status;
 657
 658         status =  db_ctdb_transaction_store(h, rec->key, tdb_null);
 659         return status;
 660 }
 661
 662 static void db_ctdb_fetch_db_seqnum_parser(
 663         TDB_DATA key, struct ctdb_ltdb_header *header,
 664         TDB_DATA data, void *private_data)
 665 {
 666         uint64_t *seqnum = (uint64_t *)private_data;
 667
 668         if (data.dsize != sizeof(uint64_t)) {
 669                 *seqnum = 0;
 670                 return;
 671         }
 672         memcpy(seqnum, data.dptr, sizeof(*seqnum));
 673 }
 674
 675 /**
 676  * Fetch the db sequence number of a persistent db directly from the db.
 677  */
 678 static NTSTATUS db_ctdb_fetch_db_seqnum_from_db(struct db_ctdb_ctx *db,
 679                                                 uint64_t *seqnum)
 680 {
 681         NTSTATUS status;
 682         TDB_DATA key;
 683
 684         if (seqnum == NULL) {
 685                 return NT_STATUS_INVALID_PARAMETER;
 686         }
 687
 688         key = string_term_tdb_data(CTDB_DB_SEQNUM_KEY);
 689
 690         status = db_ctdb_ltdb_parse(
 691                 db, key, db_ctdb_fetch_db_seqnum_parser, seqnum);
 692
 693         if (NT_STATUS_IS_OK(status)) {
 694                 return NT_STATUS_OK;
 695         }
 696         if (NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND)) {
 697                 *seqnum = 0;
 698                 return NT_STATUS_OK;
 699         }
 700         return status;
 701 }
 702
 703 /**
 704  * Store the database sequence number inside a transaction.
 705  */
 706 static NTSTATUS db_ctdb_store_db_seqnum(struct db_ctdb_transaction_handle *h,
 707                                         uint64_t seqnum)
 708 {
 709         NTSTATUS status;
 710         const char *keyname = CTDB_DB_SEQNUM_KEY;
 711         TDB_DATA key;
 712         TDB_DATA data;
 713
 714         key = string_term_tdb_data(keyname);
 715
 716         data.dptr = (uint8_t *)&seqnum;
 717         data.dsize = sizeof(uint64_t);
 718
 719         status = db_ctdb_transaction_store(h, key, data);
 720
 721         return status;
 722 }
 723
 724 /*
 725   commit a transaction
 726  */
 727 static int db_ctdb_transaction_commit(struct db_context *db)
 728 {
 729         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 730                                                         struct db_ctdb_ctx);
 731         NTSTATUS rets;
 732         int status;
 733         struct db_ctdb_transaction_handle *h = ctx->transaction;
 734         uint64_t old_seqnum, new_seqnum;
 735         int ret;
 736
 737         if (h == NULL) {
 738                 DEBUG(0,(__location__ " transaction commit with no open transaction on db 0x%08x\n", ctx->db_id));
 739                 return -1;
 740         }
 741
 742         if (h->nested_cancel) {
 743                 db->transaction_cancel(db);
 744                 DEBUG(5,(__location__ " Failed transaction commit after nested cancel\n"));
 745                 return -1;
 746         }
 747
 748         if (h->nesting != 0) {
 749                 h->nesting--;
 750                 DEBUG(5, (__location__ " transaction commit on db 0x%08x: nesting %d -> %d\n",
 751                           ctx->db_id, ctx->transaction->nesting + 1, ctx->transaction->nesting));
 752                 return 0;
 753         }
 754
 755         if (h->m_write == NULL) {
 756                 /*
 757                  * No changes were made, so don't change the seqnum,
 758                  * don't push to other node, just exit with success.
 759                  */
 760                 ret = 0;
 761                 goto done;
 762         }
 763
 764         DEBUG(5,(__location__ " transaction commit on db 0x%08x\n", ctx->db_id));
 765
 766         /*
 767          * As the last db action before committing, bump the database sequence
 768          * number. Note that this undoes all changes to the seqnum records
 769          * performed under the transaction. This record is not meant to be
 770          * modified by user interaction. It is for internal use only...
 771          */
 772         rets = db_ctdb_fetch_db_seqnum_from_db(ctx, &old_seqnum);
 773         if (!NT_STATUS_IS_OK(rets)) {
 774                 DEBUG(1, (__location__ " failed to fetch the db sequence number "
 775                           "in transaction commit on db 0x%08x\n", ctx->db_id));
 776                 ret = -1;
 777                 goto done;
 778         }
 779
 780         new_seqnum = old_seqnum + 1;
 781
 782         rets = db_ctdb_store_db_seqnum(h, new_seqnum);
 783         if (!NT_STATUS_IS_OK(rets)) {
 784                 DEBUG(1, (__location__ "failed to store the db sequence number "
 785                           " in transaction commit on db 0x%08x\n", ctx->db_id));
 786                 ret = -1;
 787                 goto done;
 788         }
 789
 790 again:
 791         /* tell ctdbd to commit to the other nodes */
 792         rets = ctdbd_control_local(messaging_ctdbd_connection(),
 793                                    CTDB_CONTROL_TRANS3_COMMIT,
 794                                    h->ctx->db_id, 0,
 795                                    db_ctdb_marshall_finish(h->m_write),
 796                                    NULL, NULL, &status);
 797         if (!NT_STATUS_IS_OK(rets) || status != 0) {
 798                 /*
 799                  * The TRANS3_COMMIT control should only possibly fail when a
 800                  * recovery has been running concurrently. In any case, the db
 801                  * will be the same on all nodes, either the new copy or the
 802                  * old copy.  This can be detected by comparing the old and new
 803                  * local sequence numbers.
 804                  */
 805                 rets = db_ctdb_fetch_db_seqnum_from_db(ctx, &new_seqnum);
 806                 if (!NT_STATUS_IS_OK(rets)) {
 807                         DEBUG(1, (__location__ " failed to refetch db sequence "
 808                                   "number after failed TRANS3_COMMIT\n"));
 809                         ret = -1;
 810                         goto done;
 811                 }
 812
 813                 if (new_seqnum == old_seqnum) {
 814                         /* Recovery prevented all our changes: retry. */
 815                         goto again;
 816                 }
 817                 if (new_seqnum != (old_seqnum + 1)) {
 818                         DEBUG(0, (__location__ " ERROR: new_seqnum[%lu] != "
 819                                   "old_seqnum[%lu] + (0 or 1) after failed "
 820                                   "TRANS3_COMMIT - this should not happen!\n",
 821                                   (unsigned long)new_seqnum,
 822                                   (unsigned long)old_seqnum));
 823                         ret = -1;
 824                         goto done;
 825                 }
 826                 /*
 827                  * Recovery propagated our changes to all nodes, completing
 828                  * our commit for us - succeed.
 829                  */
 830         }
 831
 832         ret = 0;
 833
 834 done:
 835         h->ctx->transaction = NULL;
 836         talloc_free(h);
 837         return ret;
 838 }
 839
 840
 841 /*
 842   cancel a transaction
 843  */
 844 static int db_ctdb_transaction_cancel(struct db_context *db)
 845 {
 846         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 847                                                         struct db_ctdb_ctx);
 848         struct db_ctdb_transaction_handle *h = ctx->transaction;
 849
 850         if (h == NULL) {
 851                 DEBUG(0,(__location__ " transaction cancel with no open transaction on db 0x%08x\n", ctx->db_id));
 852                 return -1;
 853         }
 854
 855         if (h->nesting != 0) {
 856                 h->nesting--;
 857                 h->nested_cancel = true;
 858                 DEBUG(5, (__location__ " transaction cancel on db 0x%08x: nesting %d -> %d\n",
 859                           ctx->db_id, ctx->transaction->nesting + 1, ctx->transaction->nesting));
 860                 return 0;
 861         }
 862
 863         DEBUG(5,(__location__ " Cancel transaction on db 0x%08x\n", ctx->db_id));
 864
 865         ctx->transaction = NULL;
 866         talloc_free(h);
 867         return 0;
 868 }
 869
 870
 871 static NTSTATUS db_ctdb_store(struct db_record *rec, TDB_DATA data, int flag)
 872 {
 873         struct db_ctdb_rec *crec = talloc_get_type_abort(
 874                 rec->private_data, struct db_ctdb_rec);
 875
 876         return db_ctdb_ltdb_store(crec->ctdb_ctx, rec->key, &(crec->header), data);
 877 }
 878
 879
 880
 881 #ifdef HAVE_CTDB_CONTROL_SCHEDULE_FOR_DELETION_DECL
 882 static NTSTATUS db_ctdb_send_schedule_for_deletion(struct db_record *rec)
 883 {
 884         NTSTATUS status;
 885         struct ctdb_control_schedule_for_deletion *dd;
 886         TDB_DATA indata;
 887         int cstatus;
 888         struct db_ctdb_rec *crec = talloc_get_type_abort(
 889                 rec->private_data, struct db_ctdb_rec);
 890
 891         indata.dsize = offsetof(struct ctdb_control_schedule_for_deletion, key) + rec->key.dsize;
 892         indata.dptr = talloc_zero_array(crec, uint8_t, indata.dsize);
 893         if (indata.dptr == NULL) {
 894                 DEBUG(0, (__location__ " talloc failed!\n"));
 895                 return NT_STATUS_NO_MEMORY;
 896         }
 897
 898         dd = (struct ctdb_control_schedule_for_deletion *)(void *)indata.dptr;
 899         dd->db_id = crec->ctdb_ctx->db_id;
 900         dd->hdr = crec->header;
 901         dd->keylen = rec->key.dsize;
 902         memcpy(dd->key, rec->key.dptr, rec->key.dsize);
 903
 904         status = ctdbd_control_local(messaging_ctdbd_connection(),
 905                                      CTDB_CONTROL_SCHEDULE_FOR_DELETION,
 906                                      crec->ctdb_ctx->db_id,
 907                                      CTDB_CTRL_FLAG_NOREPLY, /* flags */
 908                                      indata,
 909                                      NULL, /* outdata */
 910                                      NULL, /* errmsg */
 911                                      &cstatus);
 912         talloc_free(indata.dptr);
 913
 914         if (!NT_STATUS_IS_OK(status) || cstatus != 0) {
 915                 DEBUG(1, (__location__ " Error sending local control "
 916                           "SCHEDULE_FOR_DELETION: %s, cstatus = %d\n",
 917                           nt_errstr(status), cstatus));
 918                 if (NT_STATUS_IS_OK(status)) {
 919                         status = NT_STATUS_UNSUCCESSFUL;
 920                 }
 921         }
 922
 923         return status;
 924 }
 925 #endif
 926
 927 static NTSTATUS db_ctdb_delete(struct db_record *rec)
 928 {
 929         NTSTATUS status;
 930
 931         /*
 932          * We have to store the header with empty data. TODO: Fix the
 933          * tdb-level cleanup
 934          */
 935
 936         status = db_ctdb_store(rec, tdb_null, 0);
 937         if (!NT_STATUS_IS_OK(status)) {
 938                 return status;
 939         }
 940
 941 #ifdef HAVE_CTDB_CONTROL_SCHEDULE_FOR_DELETION_DECL
 942         status = db_ctdb_send_schedule_for_deletion(rec);
 943 #endif
 944
 945         return status;
 946 }
 947
 948 static int db_ctdb_record_destr(struct db_record* data)
 949 {
 950         struct db_ctdb_rec *crec = talloc_get_type_abort(
 951                 data->private_data, struct db_ctdb_rec);
 952         int threshold;
 953         int ret;
 954         struct timeval before;
 955         double timediff;
 956
 957         DEBUG(10, (DEBUGLEVEL > 10
 958                    ? "Unlocking db %u key %s\n"
 959                    : "Unlocking db %u key %.20s\n",
 960                    (int)crec->ctdb_ctx->db_id,
 961                    hex_encode_talloc(data, (unsigned char *)data->key.dptr,
 962                               data->key.dsize)));
 963
 964         before = timeval_current();
 965
 966         ret = tdb_chainunlock(crec->ctdb_ctx->wtdb->tdb, data->key);
 967
 968         timediff = timeval_elapsed(&before);
 969         timediff *= 1000;       /* get us milliseconds */
 970
 971         if (timediff > crec->ctdb_ctx->warn_unlock_msecs) {
 972                 char *key;
 973                 key = hex_encode_talloc(talloc_tos(),
 974                                         (unsigned char *)data->key.dptr,
 975                                         data->key.dsize);
 976                 DEBUG(0, ("tdb_chainunlock on db %s, key %s took %f milliseconds\n",
 977                           tdb_name(crec->ctdb_ctx->wtdb->tdb), key,
 978                           timediff));
 979                 TALLOC_FREE(key);
 980         }
 981
 982         if (ret != 0) {
 983                 DEBUG(0, ("tdb_chainunlock failed\n"));
 984                 return -1;
 985         }
 986
 987         threshold = crec->ctdb_ctx->warn_locktime_msecs;
 988         if (threshold != 0) {
 989                 timediff = timeval_elapsed(&crec->lock_time);
 990                 if ((timediff * 1000) > threshold) {
 991                         const char *key;
 992
 993                         key = hex_encode_talloc(data,
 994                                                 (unsigned char *)data->key.dptr,
 995                                                 data->key.dsize);
 996                         DEBUG(0, ("Held tdb lock on db %s, key %s %f seconds\n",
 997                                   tdb_name(crec->ctdb_ctx->wtdb->tdb), key,
 998                                   timediff));
 999                 }
1000         }
1001
1002         return 0;
1003 }
1004
1005 /**
1006  * Check whether we have a valid local copy of the given record,
1007  * either for reading or for writing.
1008  */
1009 static bool db_ctdb_can_use_local_hdr(const struct ctdb_ltdb_header *hdr,
1010                                       bool read_only)
1011 {
1012 #ifdef HAVE_CTDB_WANT_READONLY_DECL
1013         if (hdr->dmaster != get_my_vnn()) {
1014                 /* If we're not dmaster, it must be r/o copy. */
1015                 return read_only && (hdr->flags & CTDB_REC_RO_HAVE_READONLY);
1016         }
1017
1018         /*
1019          * If we want write access, no one may have r/o copies.
1020          */
1021         return read_only || !(hdr->flags & CTDB_REC_RO_HAVE_DELEGATIONS);
1022 #else
1023         return (hdr->dmaster == get_my_vnn());
1024 #endif
1025 }
1026
1027 static bool db_ctdb_can_use_local_copy(TDB_DATA ctdb_data, bool read_only)
1028 {
1029         if (ctdb_data.dptr == NULL) {
1030                 return false;
1031         }
1032
1033         if (ctdb_data.dsize < sizeof(struct ctdb_ltdb_header)) {
1034                 return false;
1035         }
1036
1037         return db_ctdb_can_use_local_hdr(
1038                 (struct ctdb_ltdb_header *)ctdb_data.dptr, read_only);
1039 }
1040
1041 static struct db_record *fetch_locked_internal(struct db_ctdb_ctx *ctx,
1042                                                TALLOC_CTX *mem_ctx,
1043                                                TDB_DATA key,
1044                                                bool tryonly)
1045 {
1046         struct db_record *result;
1047         struct db_ctdb_rec *crec;
1048         NTSTATUS status;
1049         TDB_DATA ctdb_data;
1050         int migrate_attempts;
1051         struct timeval migrate_start;
1052         struct timeval chainlock_start;
1053         struct timeval ctdb_start_time;
1054         double chainlock_time = 0;
1055         double ctdb_time = 0;
1056         int duration_msecs;
1057         int lockret;
1058
1059         if (!(result = talloc(mem_ctx, struct db_record))) {
1060                 DEBUG(0, ("talloc failed\n"));
1061                 return NULL;
1062         }
1063
1064         if (!(crec = talloc_zero(result, struct db_ctdb_rec))) {
1065                 DEBUG(0, ("talloc failed\n"));
1066                 TALLOC_FREE(result);
1067                 return NULL;
1068         }
1069
1070         result->db = ctx->db;
1071         result->private_data = (void *)crec;
1072         crec->ctdb_ctx = ctx;
1073
1074         result->key.dsize = key.dsize;
1075         result->key.dptr = (uint8_t *)talloc_memdup(result, key.dptr,
1076                                                     key.dsize);
1077         if (result->key.dptr == NULL) {
1078                 DEBUG(0, ("talloc failed\n"));
1079                 TALLOC_FREE(result);
1080                 return NULL;
1081         }
1082
1083         migrate_attempts = 0;
1084         GetTimeOfDay(&migrate_start);
1085
1086         /*
1087          * Do a blocking lock on the record
1088          */
1089 again:
1090
1091         if (DEBUGLEVEL >= 10) {
1092                 char *keystr = hex_encode_talloc(result, key.dptr, key.dsize);
1093                 DEBUG(10, (DEBUGLEVEL > 10
1094                            ? "Locking db %u key %s\n"
1095                            : "Locking db %u key %.20s\n",
1096                            (int)crec->ctdb_ctx->db_id, keystr));
1097                 TALLOC_FREE(keystr);
1098         }
1099
1100         GetTimeOfDay(&chainlock_start);
1101         lockret = tryonly
1102                 ? tdb_chainlock_nonblock(ctx->wtdb->tdb, key)
1103                 : tdb_chainlock(ctx->wtdb->tdb, key);
1104         chainlock_time += timeval_elapsed(&chainlock_start);
1105
1106         if (lockret != 0) {
1107                 DEBUG(3, ("tdb_chainlock failed\n"));
1108                 TALLOC_FREE(result);
1109                 return NULL;
1110         }
1111
1112         result->store = db_ctdb_store;
1113         result->delete_rec = db_ctdb_delete;
1114         talloc_set_destructor(result, db_ctdb_record_destr);
1115
1116         ctdb_data = tdb_fetch_compat(ctx->wtdb->tdb, key);
1117
1118         /*
1119          * See if we have a valid record and we are the dmaster. If so, we can
1120          * take the shortcut and just return it.
1121          */
1122
1123         if (!db_ctdb_can_use_local_copy(ctdb_data, false)) {
1124                 SAFE_FREE(ctdb_data.dptr);
1125                 tdb_chainunlock(ctx->wtdb->tdb, key);
1126                 talloc_set_destructor(result, NULL);
1127
1128                 if (tryonly && (migrate_attempts != 0)) {
1129                         DEBUG(5, ("record migrated away again\n"));
1130                         TALLOC_FREE(result);
1131                         return NULL;
1132                 }
1133
1134                 migrate_attempts += 1;
1135
1136                 DEBUG(10, ("ctdb_data.dptr = %p, dmaster = %u (%u) %u\n",
1137                            ctdb_data.dptr, ctdb_data.dptr ?
1138                            ((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster : -1,
1139                            get_my_vnn(),
1140                            ctdb_data.dptr ?
1141                            ((struct ctdb_ltdb_header *)ctdb_data.dptr)->flags : 0));
1142
1143                 GetTimeOfDay(&ctdb_start_time);
1144                 status = ctdbd_migrate(messaging_ctdbd_connection(), ctx->db_id,
1145                                        key);
1146                 ctdb_time += timeval_elapsed(&ctdb_start_time);
1147
1148                 if (!NT_STATUS_IS_OK(status)) {
1149                         DEBUG(5, ("ctdb_migrate failed: %s\n",
1150                                   nt_errstr(status)));
1151                         TALLOC_FREE(result);
1152                         return NULL;
1153                 }
1154                 /* now its migrated, try again */
1155                 goto again;
1156         }
1157
1158         {
1159                 double duration;
1160                 duration = timeval_elapsed(&migrate_start);
1161
1162                 /*
1163                  * Convert the duration to milliseconds to avoid a
1164                  * floating-point division of
1165                  * lp_parm_int("migrate_duration") by 1000.
1166                  */
1167                 duration_msecs = duration * 1000;
1168         }
1169
1170         if ((migrate_attempts > ctx->warn_migrate_attempts) ||
1171             (duration_msecs > ctx->warn_migrate_msecs)) {
1172                 int chain = 0;
1173
1174                 if (tdb_get_flags(ctx->wtdb->tdb) & TDB_INCOMPATIBLE_HASH) {
1175                         chain = tdb_jenkins_hash(&key) %
1176                                 tdb_hash_size(ctx->wtdb->tdb);
1177                 }
1178
1179                 DEBUG(0, ("db_ctdb_fetch_locked for %s key %s, chain %d "
1180                           "needed %d attempts, %d milliseconds, "
1181                           "chainlock: %d ms, CTDB %d ms\n",
1182                           tdb_name(ctx->wtdb->tdb),
1183                           hex_encode_talloc(talloc_tos(),
1184                                             (unsigned char *)key.dptr,
1185                                             key.dsize),
1186                           chain,
1187                           migrate_attempts, duration_msecs,
1188                           (int) chainlock_time * 1000,
1189                           (int) ctdb_time * 1000));
1190         }
1191
1192         GetTimeOfDay(&crec->lock_time);
1193
1194         memcpy(&crec->header, ctdb_data.dptr, sizeof(crec->header));
1195
1196         result->value.dsize = ctdb_data.dsize - sizeof(crec->header);
1197         result->value.dptr = NULL;
1198
1199         if ((result->value.dsize != 0)
1200             && !(result->value.dptr = (uint8_t *)talloc_memdup(
1201                          result, ctdb_data.dptr + sizeof(crec->header),
1202                          result->value.dsize))) {
1203                 DEBUG(0, ("talloc failed\n"));
1204                 TALLOC_FREE(result);
1205         }
1206
1207         SAFE_FREE(ctdb_data.dptr);
1208
1209         return result;
1210 }
1211
1212 static struct db_record *db_ctdb_fetch_locked(struct db_context *db,
1213                                               TALLOC_CTX *mem_ctx,
1214                                               TDB_DATA key)
1215 {
1216         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1217                                                         struct db_ctdb_ctx);
1218
1219         if (ctx->transaction != NULL) {
1220                 return db_ctdb_fetch_locked_transaction(ctx, mem_ctx, key);
1221         }
1222
1223         if (db->persistent) {
1224                 return db_ctdb_fetch_locked_persistent(ctx, mem_ctx, key);
1225         }
1226
1227         return fetch_locked_internal(ctx, mem_ctx, key, false);
1228 }
1229
1230 static struct db_record *db_ctdb_try_fetch_locked(struct db_context *db,
1231                                                   TALLOC_CTX *mem_ctx,
1232                                                   TDB_DATA key)
1233 {
1234         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1235                                                         struct db_ctdb_ctx);
1236
1237         if (ctx->transaction != NULL) {
1238                 return db_ctdb_fetch_locked_transaction(ctx, mem_ctx, key);
1239         }
1240
1241         if (db->persistent) {
1242                 return db_ctdb_fetch_locked_persistent(ctx, mem_ctx, key);
1243         }
1244
1245         return fetch_locked_internal(ctx, mem_ctx, key, true);
1246 }
1247
1248 struct db_ctdb_parse_record_state {
1249         void (*parser)(TDB_DATA key, TDB_DATA data, void *private_data);
1250         void *private_data;
1251         bool ask_for_readonly_copy;
1252         bool done;
1253 };
1254
1255 static void db_ctdb_parse_record_parser(
1256         TDB_DATA key, struct ctdb_ltdb_header *header,
1257         TDB_DATA data, void *private_data)
1258 {
1259         struct db_ctdb_parse_record_state *state =
1260                 (struct db_ctdb_parse_record_state *)private_data;
1261         state->parser(key, data, state->private_data);
1262 }
1263
1264 static void db_ctdb_parse_record_parser_nonpersistent(
1265         TDB_DATA key, struct ctdb_ltdb_header *header,
1266         TDB_DATA data, void *private_data)
1267 {
1268         struct db_ctdb_parse_record_state *state =
1269                 (struct db_ctdb_parse_record_state *)private_data;
1270
1271         if (db_ctdb_can_use_local_hdr(header, true)) {
1272                 state->parser(key, data, state->private_data);
1273                 state->done = true;
1274         } else {
1275                 /*
1276                  * We found something in the db, so it seems that this record,
1277                  * while not usable locally right now, is popular. Ask for a
1278                  * R/O copy.
1279                  */
1280                 state->ask_for_readonly_copy = true;
1281         }
1282 }
1283
1284 static NTSTATUS db_ctdb_parse_record(struct db_context *db, TDB_DATA key,
1285                                      void (*parser)(TDB_DATA key,
1286                                                     TDB_DATA data,
1287                                                     void *private_data),
1288                                      void *private_data)
1289 {
1290         struct db_ctdb_ctx *ctx = talloc_get_type_abort(
1291                 db->private_data, struct db_ctdb_ctx);
1292         struct db_ctdb_parse_record_state state;
1293         NTSTATUS status;
1294
1295         state.parser = parser;
1296         state.private_data = private_data;
1297
1298         if (ctx->transaction != NULL) {
1299                 struct db_ctdb_transaction_handle *h = ctx->transaction;
1300                 bool found;
1301
1302                 /*
1303                  * Transactions only happen for persistent db's.
1304                  */
1305
1306                 found = parse_newest_in_marshall_buffer(
1307                         h->m_write, key, db_ctdb_parse_record_parser, &state);
1308
1309                 if (found) {
1310                         return NT_STATUS_OK;
1311                 }
1312         }
1313
1314         if (db->persistent) {
1315                 /*
1316                  * Persistent db, but not found in the transaction buffer
1317                  */
1318                 return db_ctdb_ltdb_parse(
1319                         ctx, key, db_ctdb_parse_record_parser, &state);
1320         }
1321
1322         state.done = false;
1323         state.ask_for_readonly_copy = false;
1324
1325         status = db_ctdb_ltdb_parse(
1326                 ctx, key, db_ctdb_parse_record_parser_nonpersistent, &state);
1327         if (NT_STATUS_IS_OK(status) && state.done) {
1328                 return NT_STATUS_OK;
1329         }
1330
1331         return ctdbd_parse(messaging_ctdbd_connection(), ctx->db_id, key,
1332                            state.ask_for_readonly_copy, parser, private_data);
1333 }
1334
1335 struct traverse_state {
1336         struct db_context *db;
1337         int (*fn)(struct db_record *rec, void *private_data);
1338         void *private_data;
1339         int count;
1340 };
1341
1342 static void traverse_callback(TDB_DATA key, TDB_DATA data, void *private_data)
1343 {
1344         struct traverse_state *state = (struct traverse_state *)private_data;
1345         struct db_record *rec;
1346         TALLOC_CTX *tmp_ctx = talloc_new(state->db);
1347         /* we have to give them a locked record to prevent races */
1348         rec = db_ctdb_fetch_locked(state->db, tmp_ctx, key);
1349         if (rec && rec->value.dsize > 0) {
1350                 state->fn(rec, state->private_data);
1351         }
1352         talloc_free(tmp_ctx);
1353 }
1354
1355 static int traverse_persistent_callback(TDB_CONTEXT *tdb, TDB_DATA kbuf, TDB_DATA dbuf,
1356                                         void *private_data)
1357 {
1358         struct traverse_state *state = (struct traverse_state *)private_data;
1359         struct db_record *rec;
1360         TALLOC_CTX *tmp_ctx = talloc_new(state->db);
1361         int ret = 0;
1362
1363         /*
1364          * Skip the __db_sequence_number__ key:
1365          * This is used for persistent transactions internally.
1366          */
1367         if (kbuf.dsize == strlen(CTDB_DB_SEQNUM_KEY) + 1 &&
1368             strcmp((const char*)kbuf.dptr, CTDB_DB_SEQNUM_KEY) == 0)
1369         {
1370                 goto done;
1371         }
1372
1373         /* we have to give them a locked record to prevent races */
1374         rec = db_ctdb_fetch_locked(state->db, tmp_ctx, kbuf);
1375         if (rec && rec->value.dsize > 0) {
1376                 ret = state->fn(rec, state->private_data);
1377         }
1378
1379 done:
1380         talloc_free(tmp_ctx);
1381         return ret;
1382 }
1383
1384 /* wrapper to use traverse_persistent_callback with dbwrap */
1385 static int traverse_persistent_callback_dbwrap(struct db_record *rec, void* data)
1386 {
1387         return traverse_persistent_callback(NULL, rec->key, rec->value, data);
1388 }
1389
1390
1391 static int db_ctdb_traverse(struct db_context *db,
1392                             int (*fn)(struct db_record *rec,
1393                                       void *private_data),
1394                             void *private_data)
1395 {
1396         NTSTATUS status;
1397         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1398                                                         struct db_ctdb_ctx);
1399         struct traverse_state state;
1400
1401         state.db = db;
1402         state.fn = fn;
1403         state.private_data = private_data;
1404         state.count = 0;
1405
1406         if (db->persistent) {
1407                 struct tdb_context *ltdb = ctx->wtdb->tdb;
1408                 int ret;
1409
1410                 /* for persistent databases we don't need to do a ctdb traverse,
1411                    we can do a faster local traverse */
1412                 ret = tdb_traverse(ltdb, traverse_persistent_callback, &state);
1413                 if (ret < 0) {
1414                         return ret;
1415                 }
1416                 if (ctx->transaction && ctx->transaction->m_write) {
1417                         /*
1418                          * we now have to handle keys not yet
1419                          * present at transaction start
1420                          */
1421                         struct db_context *newkeys = db_open_rbt(talloc_tos());
1422                         struct ctdb_marshall_buffer *mbuf = ctx->transaction->m_write;
1423                         struct ctdb_rec_data *rec=NULL;
1424                         int i;
1425                         int count = 0;
1426
1427                         if (newkeys == NULL) {
1428                                 return -1;
1429                         }
1430
1431                         for (i=0; i<mbuf->count; i++) {
1432                                 TDB_DATA key;
1433                                 rec = db_ctdb_marshall_loop_next_key(
1434                                         mbuf, rec, &key);
1435                                 SMB_ASSERT(rec != NULL);
1436
1437                                 if (!tdb_exists(ltdb, key)) {
1438                                         dbwrap_store(newkeys, key, tdb_null, 0);
1439                                 }
1440                         }
1441                         status = dbwrap_traverse(newkeys,
1442                                                  traverse_persistent_callback_dbwrap,
1443                                                  &state,
1444                                                  &count);
1445                         talloc_free(newkeys);
1446                         if (!NT_STATUS_IS_OK(status)) {
1447                                 return -1;
1448                         }
1449                         ret += count;
1450                 }
1451                 return ret;
1452         }
1453
1454         status = ctdbd_traverse(ctx->db_id, traverse_callback, &state);
1455         if (!NT_STATUS_IS_OK(status)) {
1456                 return -1;
1457         }
1458         return state.count;
1459 }
1460
1461 static NTSTATUS db_ctdb_store_deny(struct db_record *rec, TDB_DATA data, int flag)
1462 {
1463         return NT_STATUS_MEDIA_WRITE_PROTECTED;
1464 }
1465
1466 static NTSTATUS db_ctdb_delete_deny(struct db_record *rec)
1467 {
1468         return NT_STATUS_MEDIA_WRITE_PROTECTED;
1469 }
1470
1471 static void traverse_read_callback(TDB_DATA key, TDB_DATA data, void *private_data)
1472 {
1473         struct traverse_state *state = (struct traverse_state *)private_data;
1474         struct db_record rec;
1475
1476         ZERO_STRUCT(rec);
1477         rec.db = state->db;
1478         rec.key = key;
1479         rec.value = data;
1480         rec.store = db_ctdb_store_deny;
1481         rec.delete_rec = db_ctdb_delete_deny;
1482         rec.private_data = NULL;
1483         state->fn(&rec, state->private_data);
1484         state->count++;
1485 }
1486
1487 static int traverse_persistent_callback_read(TDB_CONTEXT *tdb, TDB_DATA kbuf, TDB_DATA dbuf,
1488                                         void *private_data)
1489 {
1490         struct traverse_state *state = (struct traverse_state *)private_data;
1491         struct db_record rec;
1492
1493         /*
1494          * Skip the __db_sequence_number__ key:
1495          * This is used for persistent transactions internally.
1496          */
1497         if (kbuf.dsize == strlen(CTDB_DB_SEQNUM_KEY) + 1 &&
1498             strcmp((const char*)kbuf.dptr, CTDB_DB_SEQNUM_KEY) == 0)
1499         {
1500                 return 0;
1501         }
1502
1503         ZERO_STRUCT(rec);
1504         rec.db = state->db;
1505         rec.key = kbuf;
1506         rec.value = dbuf;
1507         rec.store = db_ctdb_store_deny;
1508         rec.delete_rec = db_ctdb_delete_deny;
1509         rec.private_data = NULL;
1510
1511         if (rec.value.dsize <= sizeof(struct ctdb_ltdb_header)) {
1512                 /* a deleted record */
1513                 return 0;
1514         }
1515         rec.value.dsize -= sizeof(struct ctdb_ltdb_header);
1516         rec.value.dptr += sizeof(struct ctdb_ltdb_header);
1517
1518         state->count++;
1519         return state->fn(&rec, state->private_data);
1520 }
1521
1522 static int db_ctdb_traverse_read(struct db_context *db,
1523                                  int (*fn)(struct db_record *rec,
1524                                            void *private_data),
1525                                  void *private_data)
1526 {
1527         NTSTATUS status;
1528         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1529                                                         struct db_ctdb_ctx);
1530         struct traverse_state state;
1531
1532         state.db = db;
1533         state.fn = fn;
1534         state.private_data = private_data;
1535         state.count = 0;
1536
1537         if (db->persistent) {
1538                 /* for persistent databases we don't need to do a ctdb traverse,
1539                    we can do a faster local traverse */
1540                 return tdb_traverse_read(ctx->wtdb->tdb, traverse_persistent_callback_read, &state);
1541         }
1542
1543         status = ctdbd_traverse(ctx->db_id, traverse_read_callback, &state);
1544         if (!NT_STATUS_IS_OK(status)) {
1545                 return -1;
1546         }
1547         return state.count;
1548 }
1549
1550 static int db_ctdb_get_seqnum(struct db_context *db)
1551 {
1552         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
1553                                                         struct db_ctdb_ctx);
1554         return tdb_get_seqnum(ctx->wtdb->tdb);
1555 }
1556
1557 static void db_ctdb_id(struct db_context *db, const uint8_t **id,
1558                        size_t *idlen)
1559 {
1560         struct db_ctdb_ctx *ctx = talloc_get_type_abort(
1561                 db->private_data, struct db_ctdb_ctx);
1562
1563         *id = (uint8_t *)&ctx->db_id;
1564         *idlen = sizeof(ctx->db_id);
1565 }
1566
1567 struct db_context *db_open_ctdb(TALLOC_CTX *mem_ctx,
1568                                 const char *name,
1569                                 int hash_size, int tdb_flags,
1570                                 int open_flags, mode_t mode,
1571                                 enum dbwrap_lock_order lock_order)
1572 {
1573         struct db_context *result;
1574         struct db_ctdb_ctx *db_ctdb;
1575         char *db_path;
1576         struct ctdbd_connection *conn;
1577         struct loadparm_context *lp_ctx;
1578         struct ctdb_db_priority prio;
1579         NTSTATUS status;
1580         int cstatus;
1581
1582         if (!lp_clustering()) {
1583                 DEBUG(10, ("Clustering disabled -- no ctdb\n"));
1584                 return NULL;
1585         }
1586
1587         if (!(result = talloc_zero(mem_ctx, struct db_context))) {
1588                 DEBUG(0, ("talloc failed\n"));
1589                 TALLOC_FREE(result);
1590                 return NULL;
1591         }
1592
1593         if (!(db_ctdb = talloc(result, struct db_ctdb_ctx))) {
1594                 DEBUG(0, ("talloc failed\n"));
1595                 TALLOC_FREE(result);
1596                 return NULL;
1597         }
1598
1599         result->name = talloc_strdup(result, name);
1600         if (result->name == NULL) {
1601                 DEBUG(0, ("talloc failed\n"));
1602                 TALLOC_FREE(result);
1603                 return NULL;
1604         }
1605
1606         db_ctdb->transaction = NULL;
1607         db_ctdb->db = result;
1608
1609         conn = messaging_ctdbd_connection();
1610         if (conn == NULL) {
1611                 DEBUG(1, ("Could not connect to ctdb\n"));
1612                 TALLOC_FREE(result);
1613                 return NULL;
1614         }
1615
1616         if (!NT_STATUS_IS_OK(ctdbd_db_attach(conn, name, &db_ctdb->db_id, tdb_flags))) {
1617                 DEBUG(0, ("ctdbd_db_attach failed for %s\n", name));
1618                 TALLOC_FREE(result);
1619                 return NULL;
1620         }
1621
1622         db_path = ctdbd_dbpath(conn, db_ctdb, db_ctdb->db_id);
1623
1624         result->persistent = ((tdb_flags & TDB_CLEAR_IF_FIRST) == 0);
1625         result->lock_order = lock_order;
1626
1627         /* only pass through specific flags */
1628         tdb_flags &= TDB_SEQNUM;
1629
1630         /* honor permissions if user has specified O_CREAT */
1631         if (open_flags & O_CREAT) {
1632                 chmod(db_path, mode);
1633         }
1634
1635         prio.db_id = db_ctdb->db_id;
1636         prio.priority = lock_order;
1637
1638         status = ctdbd_control_local(
1639                 conn, CTDB_CONTROL_SET_DB_PRIORITY, 0, 0,
1640                 make_tdb_data((uint8_t *)&prio, sizeof(prio)),
1641                 NULL, NULL, &cstatus);
1642
1643         if (!NT_STATUS_IS_OK(status) || (cstatus != 0)) {
1644                 DEBUG(1, ("CTDB_CONTROL_SET_DB_PRIORITY failed: %s, %d\n",
1645                           nt_errstr(status), cstatus));
1646                 TALLOC_FREE(result);
1647                 return NULL;
1648         }
1649
1650         lp_ctx = loadparm_init_s3(db_path, loadparm_s3_helpers());
1651
1652         db_ctdb->wtdb = tdb_wrap_open(db_ctdb, db_path, hash_size, tdb_flags,
1653                                       O_RDWR, 0, lp_ctx);
1654         talloc_unlink(db_path, lp_ctx);
1655         if (db_ctdb->wtdb == NULL) {
1656                 DEBUG(0, ("Could not open tdb %s: %s\n", db_path, strerror(errno)));
1657                 TALLOC_FREE(result);
1658                 return NULL;
1659         }
1660         talloc_free(db_path);
1661
1662         if (result->persistent) {
1663                 db_ctdb->lock_ctx = g_lock_ctx_init(db_ctdb,
1664                                                     ctdb_conn_msg_ctx(conn));
1665                 if (db_ctdb->lock_ctx == NULL) {
1666                         DEBUG(0, ("g_lock_ctx_init failed\n"));
1667                         TALLOC_FREE(result);
1668                         return NULL;
1669                 }
1670         }
1671
1672         db_ctdb->warn_unlock_msecs = lp_parm_int(-1, "ctdb",
1673                                                  "unlock_warn_threshold", 5);
1674         db_ctdb->warn_migrate_attempts = lp_parm_int(-1, "ctdb",
1675                                                      "migrate_attempts", 10);
1676         db_ctdb->warn_migrate_msecs = lp_parm_int(-1, "ctdb",
1677                                                   "migrate_duration", 5000);
1678         db_ctdb->warn_locktime_msecs = lp_ctdb_locktime_warn_threshold();
1679
1680         result->private_data = (void *)db_ctdb;
1681         result->fetch_locked = db_ctdb_fetch_locked;
1682         result->try_fetch_locked = db_ctdb_try_fetch_locked;
1683         result->parse_record = db_ctdb_parse_record;
1684         result->traverse = db_ctdb_traverse;
1685         result->traverse_read = db_ctdb_traverse_read;
1686         result->get_seqnum = db_ctdb_get_seqnum;
1687         result->transaction_start = db_ctdb_transaction_start;
1688         result->transaction_commit = db_ctdb_transaction_commit;
1689         result->transaction_cancel = db_ctdb_transaction_cancel;
1690         result->id = db_ctdb_id;
1691         result->stored_callback = NULL;
1692
1693         DEBUG(3,("db_open_ctdb: opened database '%s' with dbid 0x%x\n",
1694                  name, db_ctdb->db_id));
1695
1696         return result;
1697 }
1698
1699 #else /* CLUSTER_SUPPORT */
1700
1701 struct db_context *db_open_ctdb(TALLOC_CTX *mem_ctx,
1702                                 const char *name,
1703                                 int hash_size, int tdb_flags,
1704                                 int open_flags, mode_t mode,
1705                                 enum dbwrap_lock_order lock_order)
1706 {
1707         DEBUG(3, ("db_open_ctdb: no cluster support!\n"));
1708         errno = ENOSYS;
1709         return NULL;
1710 }
1711
1712 #endif