source/lib/dbwrap_ctdb.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Database interface wrapper around ctdbd
   4    Copyright (C) Volker Lendecke 2007
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "includes.h"
  21 #ifdef CLUSTER_SUPPORT
  22 #include "ctdb.h"
  23 #include "ctdb_private.h"
  24 #include "ctdbd_conn.h"
  25
  26 struct db_ctdb_ctx {
  27         struct tdb_wrap *wtdb;
  28         uint32 db_id;
  29 };
  30
  31 struct db_ctdb_rec {
  32         struct db_ctdb_ctx *ctdb_ctx;
  33         struct ctdb_ltdb_header header;
  34 };
  35
  36 static NTSTATUS db_ctdb_store(struct db_record *rec, TDB_DATA data, int flag)
  37 {
  38         struct db_ctdb_rec *crec = talloc_get_type_abort(
  39                 rec->private_data, struct db_ctdb_rec);
  40         TDB_DATA cdata;
  41         int ret;
  42
  43         cdata.dsize = sizeof(crec->header) + data.dsize;
  44
  45         if (!(cdata.dptr = SMB_MALLOC_ARRAY(uint8, cdata.dsize))) {
  46                 return NT_STATUS_NO_MEMORY;
  47         }
  48
  49         memcpy(cdata.dptr, &crec->header, sizeof(crec->header));
  50         memcpy(cdata.dptr + sizeof(crec->header), data.dptr, data.dsize);
  51
  52         ret = tdb_store(crec->ctdb_ctx->wtdb->tdb, rec->key, cdata, TDB_REPLACE);
  53
  54         SAFE_FREE(cdata.dptr);
  55
  56         return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
  57 }
  58
  59
  60 /* for persistent databases the store is a bit different. We have to
  61    ask the ctdb daemon to push the record to all nodes after the
  62    store */
  63 static NTSTATUS db_ctdb_store_persistent(struct db_record *rec, TDB_DATA data, int flag)
  64 {
  65         struct db_ctdb_rec *crec = talloc_get_type_abort(
  66                 rec->private_data, struct db_ctdb_rec);
  67         TDB_DATA cdata;
  68         int ret;
  69         NTSTATUS status;
  70
  71         cdata.dsize = sizeof(crec->header) + data.dsize;
  72
  73         if (!(cdata.dptr = SMB_MALLOC_ARRAY(uint8, cdata.dsize))) {
  74                 return NT_STATUS_NO_MEMORY;
  75         }
  76
  77         crec->header.rsn++;
  78
  79         memcpy(cdata.dptr, &crec->header, sizeof(crec->header));
  80         memcpy(cdata.dptr + sizeof(crec->header), data.dptr, data.dsize);
  81
  82         ret = tdb_store(crec->ctdb_ctx->wtdb->tdb, rec->key, cdata, TDB_REPLACE);
  83         status = (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
  84
  85         /* now tell ctdbd to update this record on all other nodes */
  86         if (NT_STATUS_IS_OK(status)) {
  87                 status = ctdbd_persistent_store(messaging_ctdbd_connection(), crec->ctdb_ctx->db_id, rec->key, cdata);
  88         }
  89
  90         SAFE_FREE(cdata.dptr);
  91
  92         return status;
  93 }
  94
  95 static NTSTATUS db_ctdb_delete(struct db_record *rec)
  96 {
  97         struct db_ctdb_rec *crec = talloc_get_type_abort(
  98                 rec->private_data, struct db_ctdb_rec);
  99         TDB_DATA data;
 100         int ret;
 101
 102         /*
 103          * We have to store the header with empty data. TODO: Fix the
 104          * tdb-level cleanup
 105          */
 106
 107         data.dptr = (uint8 *)&crec->header;
 108         data.dsize = sizeof(crec->header);
 109
 110         ret = tdb_store(crec->ctdb_ctx->wtdb->tdb, rec->key, data, TDB_REPLACE);
 111
 112         return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
 113 }
 114
 115 static int db_ctdb_record_destr(struct db_record* data)
 116 {
 117         struct db_ctdb_rec *crec = talloc_get_type_abort(
 118                 data->private_data, struct db_ctdb_rec);
 119
 120         DEBUG(10, (DEBUGLEVEL > 10
 121                    ? "Unlocking db %u key %s\n"
 122                    : "Unlocking db %u key %.20s\n",
 123                    (int)crec->ctdb_ctx->db_id,
 124                    hex_encode(data, (unsigned char *)data->key.dptr,
 125                               data->key.dsize)));
 126
 127         if (tdb_chainunlock(crec->ctdb_ctx->wtdb->tdb, data->key) != 0) {
 128                 DEBUG(0, ("tdb_chainunlock failed\n"));
 129                 return -1;
 130         }
 131
 132         return 0;
 133 }
 134
 135 static struct db_record *db_ctdb_fetch_locked(struct db_context *db,
 136                                               TALLOC_CTX *mem_ctx,
 137                                               TDB_DATA key)
 138 {
 139         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 140                                                         struct db_ctdb_ctx);
 141         struct db_record *result;
 142         struct db_ctdb_rec *crec;
 143         NTSTATUS status;
 144         TDB_DATA ctdb_data;
 145         int migrate_attempts = 0;
 146
 147         if (!(result = talloc(mem_ctx, struct db_record))) {
 148                 DEBUG(0, ("talloc failed\n"));
 149                 return NULL;
 150         }
 151
 152         if (!(crec = TALLOC_ZERO_P(result, struct db_ctdb_rec))) {
 153                 DEBUG(0, ("talloc failed\n"));
 154                 TALLOC_FREE(result);
 155                 return NULL;
 156         }
 157
 158         result->private_data = (void *)crec;
 159         crec->ctdb_ctx = ctx;
 160
 161         result->key.dsize = key.dsize;
 162         result->key.dptr = (uint8 *)talloc_memdup(result, key.dptr, key.dsize);
 163         if (result->key.dptr == NULL) {
 164                 DEBUG(0, ("talloc failed\n"));
 165                 TALLOC_FREE(result);
 166                 return NULL;
 167         }
 168
 169         /*
 170          * Do a blocking lock on the record
 171          */
 172 again:
 173
 174         if (DEBUGLEVEL >= 10) {
 175                 char *keystr = hex_encode(result, key.dptr, key.dsize);
 176                 DEBUG(10, (DEBUGLEVEL > 10
 177                            ? "Locking db %u key %s\n"
 178                            : "Locking db %u key %.20s\n",
 179                            (int)crec->ctdb_ctx->db_id, keystr));
 180                 TALLOC_FREE(keystr);
 181         }
 182
 183         if (tdb_chainlock(ctx->wtdb->tdb, key) != 0) {
 184                 DEBUG(3, ("tdb_chainlock failed\n"));
 185                 TALLOC_FREE(result);
 186                 return NULL;
 187         }
 188
 189         if (db->persistent) {
 190                 result->store = db_ctdb_store_persistent;
 191         } else {
 192                 result->store = db_ctdb_store;
 193         }
 194         result->delete_rec = db_ctdb_delete;
 195         talloc_set_destructor(result, db_ctdb_record_destr);
 196
 197         ctdb_data = tdb_fetch(ctx->wtdb->tdb, key);
 198
 199         /*
 200          * See if we have a valid record and we are the dmaster. If so, we can
 201          * take the shortcut and just return it.
 202          */
 203
 204         if ((ctdb_data.dptr == NULL) ||
 205             (ctdb_data.dsize < sizeof(struct ctdb_ltdb_header)) ||
 206             ((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster != get_my_vnn()
 207 #if 0
 208             || (random() % 2 != 0)
 209 #endif
 210 ) {
 211                 SAFE_FREE(ctdb_data.dptr);
 212                 tdb_chainunlock(ctx->wtdb->tdb, key);
 213                 talloc_set_destructor(result, NULL);
 214
 215                 migrate_attempts += 1;
 216
 217                 DEBUG(10, ("ctdb_data.dptr = %p, dmaster = %u (%u)\n",
 218                            ctdb_data.dptr, ctdb_data.dptr ?
 219                            ((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster : -1,
 220                            get_my_vnn()));
 221
 222                 status = ctdbd_migrate(messaging_ctdbd_connection(),ctx->db_id, key);
 223                 if (!NT_STATUS_IS_OK(status)) {
 224                         DEBUG(5, ("ctdb_migrate failed: %s\n",
 225                                   nt_errstr(status)));
 226                         TALLOC_FREE(result);
 227                         return NULL;
 228                 }
 229                 /* now its migrated, try again */
 230                 goto again;
 231         }
 232
 233         if (migrate_attempts > 10) {
 234                 DEBUG(0, ("db_ctdb_fetch_locked needed %d attempts\n",
 235                           migrate_attempts));
 236         }
 237
 238         memcpy(&crec->header, ctdb_data.dptr, sizeof(crec->header));
 239
 240         result->value.dsize = ctdb_data.dsize - sizeof(crec->header);
 241         result->value.dptr = NULL;
 242
 243         if ((result->value.dsize != 0)
 244             && !(result->value.dptr = (uint8 *)talloc_memdup(
 245                          result, ctdb_data.dptr + sizeof(crec->header),
 246                          result->value.dsize))) {
 247                 DEBUG(0, ("talloc failed\n"));
 248                 TALLOC_FREE(result);
 249         }
 250
 251         SAFE_FREE(ctdb_data.dptr);
 252
 253         return result;
 254 }
 255
 256 /*
 257   fetch (unlocked, no migration) operation on ctdb
 258  */
 259 static int db_ctdb_fetch(struct db_context *db, TALLOC_CTX *mem_ctx,
 260                          TDB_DATA key, TDB_DATA *data)
 261 {
 262         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 263                                                         struct db_ctdb_ctx);
 264         NTSTATUS status;
 265         TDB_DATA ctdb_data;
 266
 267         /* try a direct fetch */
 268         ctdb_data = tdb_fetch(ctx->wtdb->tdb, key);
 269
 270         /*
 271          * See if we have a valid record and we are the dmaster. If so, we can
 272          * take the shortcut and just return it.
 273          * we bypass the dmaster check for persistent databases
 274          */
 275         if ((ctdb_data.dptr != NULL) &&
 276             (ctdb_data.dsize >= sizeof(struct ctdb_ltdb_header)) &&
 277             (db->persistent ||
 278              ((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster == get_my_vnn())) {
 279                 /* we are the dmaster - avoid the ctdb protocol op */
 280
 281                 data->dsize = ctdb_data.dsize - sizeof(struct ctdb_ltdb_header);
 282                 if (data->dsize == 0) {
 283                         SAFE_FREE(ctdb_data.dptr);
 284                         data->dptr = NULL;
 285                         return 0;
 286                 }
 287
 288                 data->dptr = (uint8 *)talloc_memdup(
 289                         mem_ctx, ctdb_data.dptr+sizeof(struct ctdb_ltdb_header),
 290                         data->dsize);
 291
 292                 SAFE_FREE(ctdb_data.dptr);
 293
 294                 if (data->dptr == NULL) {
 295                         return -1;
 296                 }
 297                 return 0;
 298         }
 299
 300         SAFE_FREE(ctdb_data.dptr);
 301
 302         /* we weren't able to get it locally - ask ctdb to fetch it for us */
 303         status = ctdbd_fetch(messaging_ctdbd_connection(),ctx->db_id, key, mem_ctx, data);
 304         if (!NT_STATUS_IS_OK(status)) {
 305                 DEBUG(5, ("ctdbd_fetch failed: %s\n", nt_errstr(status)));
 306                 return -1;
 307         }
 308
 309         return 0;
 310 }
 311
 312 struct traverse_state {
 313         struct db_context *db;
 314         int (*fn)(struct db_record *rec, void *private_data);
 315         void *private_data;
 316 };
 317
 318 static void traverse_callback(TDB_DATA key, TDB_DATA data, void *private_data)
 319 {
 320         struct traverse_state *state = (struct traverse_state *)private_data;
 321         struct db_record *rec;
 322         TALLOC_CTX *tmp_ctx = talloc_new(state->db);
 323         /* we have to give them a locked record to prevent races */
 324         rec = db_ctdb_fetch_locked(state->db, tmp_ctx, key);
 325         if (rec && rec->value.dsize > 0) {
 326                 state->fn(rec, state->private_data);
 327         }
 328         talloc_free(tmp_ctx);
 329 }
 330
 331 static int traverse_persistent_callback(TDB_CONTEXT *tdb, TDB_DATA kbuf, TDB_DATA dbuf,
 332                                         void *private_data)
 333 {
 334         struct traverse_state *state = (struct traverse_state *)private_data;
 335         struct db_record *rec;
 336         TALLOC_CTX *tmp_ctx = talloc_new(state->db);
 337         int ret = 0;
 338         /* we have to give them a locked record to prevent races */
 339         rec = db_ctdb_fetch_locked(state->db, tmp_ctx, kbuf);
 340         if (rec && rec->value.dsize > 0) {
 341                 ret = state->fn(rec, state->private_data);
 342         }
 343         talloc_free(tmp_ctx);
 344         return ret;
 345 }
 346
 347 static int db_ctdb_traverse(struct db_context *db,
 348                             int (*fn)(struct db_record *rec,
 349                                       void *private_data),
 350                             void *private_data)
 351 {
 352         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 353                                                         struct db_ctdb_ctx);
 354         struct traverse_state state;
 355
 356         state.db = db;
 357         state.fn = fn;
 358         state.private_data = private_data;
 359
 360         if (db->persistent) {
 361                 /* for persistent databases we don't need to do a ctdb traverse,
 362                    we can do a faster local traverse */
 363                 return tdb_traverse(ctx->wtdb->tdb, traverse_persistent_callback, &state);
 364         }
 365
 366
 367         ctdbd_traverse(ctx->db_id, traverse_callback, &state);
 368         return 0;
 369 }
 370
 371 static NTSTATUS db_ctdb_store_deny(struct db_record *rec, TDB_DATA data, int flag)
 372 {
 373         return NT_STATUS_MEDIA_WRITE_PROTECTED;
 374 }
 375
 376 static NTSTATUS db_ctdb_delete_deny(struct db_record *rec)
 377 {
 378         return NT_STATUS_MEDIA_WRITE_PROTECTED;
 379 }
 380
 381 static void traverse_read_callback(TDB_DATA key, TDB_DATA data, void *private_data)
 382 {
 383         struct traverse_state *state = (struct traverse_state *)private_data;
 384         struct db_record rec;
 385         rec.key = key;
 386         rec.value = data;
 387         rec.store = db_ctdb_store_deny;
 388         rec.delete_rec = db_ctdb_delete_deny;
 389         rec.private_data = state->db;
 390         state->fn(&rec, state->private_data);
 391 }
 392
 393 static int traverse_persistent_callback_read(TDB_CONTEXT *tdb, TDB_DATA kbuf, TDB_DATA dbuf,
 394                                         void *private_data)
 395 {
 396         struct traverse_state *state = (struct traverse_state *)private_data;
 397         struct db_record rec;
 398         rec.key = kbuf;
 399         rec.value = dbuf;
 400         rec.store = db_ctdb_store_deny;
 401         rec.delete_rec = db_ctdb_delete_deny;
 402         rec.private_data = state->db;
 403
 404         if (rec.value.dsize <= sizeof(struct ctdb_ltdb_header)) {
 405                 /* a deleted record */
 406                 return 0;
 407         }
 408         rec.value.dsize -= sizeof(struct ctdb_ltdb_header);
 409         rec.value.dptr += sizeof(struct ctdb_ltdb_header);
 410
 411         return state->fn(&rec, state->private_data);
 412 }
 413
 414 static int db_ctdb_traverse_read(struct db_context *db,
 415                                  int (*fn)(struct db_record *rec,
 416                                            void *private_data),
 417                                  void *private_data)
 418 {
 419         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 420                                                         struct db_ctdb_ctx);
 421         struct traverse_state state;
 422
 423         state.db = db;
 424         state.fn = fn;
 425         state.private_data = private_data;
 426
 427         if (db->persistent) {
 428                 /* for persistent databases we don't need to do a ctdb traverse,
 429                    we can do a faster local traverse */
 430                 return tdb_traverse_read(ctx->wtdb->tdb, traverse_persistent_callback_read, &state);
 431         }
 432
 433         ctdbd_traverse(ctx->db_id, traverse_read_callback, &state);
 434         return 0;
 435 }
 436
 437 static int db_ctdb_get_seqnum(struct db_context *db)
 438 {
 439         struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data,
 440                                                         struct db_ctdb_ctx);
 441         return tdb_get_seqnum(ctx->wtdb->tdb);
 442 }
 443
 444 static int db_ctdb_trans_dummy(struct db_context *db)
 445 {
 446         /*
 447          * Not implemented yet, just return ok
 448          */
 449         return 0;
 450 }
 451
 452 struct db_context *db_open_ctdb(TALLOC_CTX *mem_ctx,
 453                                 const char *name,
 454                                 int hash_size, int tdb_flags,
 455                                 int open_flags, mode_t mode)
 456 {
 457         struct db_context *result;
 458         struct db_ctdb_ctx *db_ctdb;
 459         char *db_path;
 460
 461         if (!lp_clustering()) {
 462                 DEBUG(10, ("Clustering disabled -- no ctdb\n"));
 463                 return NULL;
 464         }
 465
 466         if (!(result = TALLOC_ZERO_P(mem_ctx, struct db_context))) {
 467                 DEBUG(0, ("talloc failed\n"));
 468                 TALLOC_FREE(result);
 469                 return NULL;
 470         }
 471
 472         if (!(db_ctdb = TALLOC_P(result, struct db_ctdb_ctx))) {
 473                 DEBUG(0, ("talloc failed\n"));
 474                 TALLOC_FREE(result);
 475                 return NULL;
 476         }
 477
 478         if (!NT_STATUS_IS_OK(ctdbd_db_attach(messaging_ctdbd_connection(),name, &db_ctdb->db_id, tdb_flags))) {
 479                 DEBUG(0, ("ctdbd_db_attach failed for %s\n", name));
 480                 TALLOC_FREE(result);
 481                 return NULL;
 482         }
 483
 484         db_path = ctdbd_dbpath(messaging_ctdbd_connection(), db_ctdb, db_ctdb->db_id);
 485
 486         result->persistent = ((tdb_flags & TDB_CLEAR_IF_FIRST) == 0);
 487
 488         /* only pass through specific flags */
 489         tdb_flags &= TDB_SEQNUM;
 490
 491         /* honor permissions if user has specified O_CREAT */
 492         if (open_flags & O_CREAT) {
 493                 chmod(db_path, mode);
 494         }
 495
 496         db_ctdb->wtdb = tdb_wrap_open(db_ctdb, db_path, hash_size, tdb_flags, O_RDWR, 0);
 497         if (db_ctdb->wtdb == NULL) {
 498                 DEBUG(0, ("Could not open tdb %s: %s\n", db_path, strerror(errno)));
 499                 TALLOC_FREE(result);
 500                 return NULL;
 501         }
 502         talloc_free(db_path);
 503
 504         result->private_data = (void *)db_ctdb;
 505         result->fetch_locked = db_ctdb_fetch_locked;
 506         result->fetch = db_ctdb_fetch;
 507         result->traverse = db_ctdb_traverse;
 508         result->traverse_read = db_ctdb_traverse_read;
 509         result->get_seqnum = db_ctdb_get_seqnum;
 510         result->transaction_start = db_ctdb_trans_dummy;
 511         result->transaction_commit = db_ctdb_trans_dummy;
 512         result->transaction_cancel = db_ctdb_trans_dummy;
 513
 514         DEBUG(3,("db_open_ctdb: opened database '%s' with dbid 0x%x\n",
 515                  name, db_ctdb->db_id));
 516
 517         return result;
 518 }
 519 #endif