git.ozlabs.org Git - ccan/blob - ccan/tdb2/lock.c

   1  /*
   2    Unix SMB/CIFS implementation.
   3
   4    trivial database library
   5
   6    Copyright (C) Andrew Tridgell              1999-2005
   7    Copyright (C) Paul `Rusty' Russell              2000
   8    Copyright (C) Jeremy Allison                    2000-2003
   9
  10      ** NOTE! The following LGPL license applies to the tdb
  11      ** library. This does NOT imply that all of Samba is released
  12      ** under the LGPL
  13
  14    This library is free software; you can redistribute it and/or
  15    modify it under the terms of the GNU Lesser General Public
  16    License as published by the Free Software Foundation; either
  17    version 3 of the License, or (at your option) any later version.
  18
  19    This library is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22    Lesser General Public License for more details.
  23
  24    You should have received a copy of the GNU Lesser General Public
  25    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  26 */
  27
  28 #include "private.h"
  29 #include <assert.h>
  30 #include <ccan/build_assert/build_assert.h>
  31
  32 /* If we were threaded, we could wait for unlock, but we're not, so fail. */
  33 static enum TDB_ERROR owner_conflict(struct tdb_context *tdb, const char *call)
  34 {
  35         return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
  36                           "%s: lock owned by another tdb in this process.",
  37                           call);
  38 }
  39
  40 /* If we fork, we no longer really own locks: preserves errno */
  41 static bool check_lock_pid(struct tdb_context *tdb,
  42                            const char *call, bool log)
  43 {
  44         /* No locks?  No problem! */
  45         if (tdb->file->allrecord_lock.count == 0
  46             && tdb->file->num_lockrecs == 0) {
  47                 return true;
  48         }
  49
  50         /* No fork?  No problem! */
  51         if (tdb->file->locker == getpid()) {
  52                 return true;
  53         }
  54
  55         if (log) {
  56                 tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
  57                            "%s: fork() detected after lock acquisition!"
  58                            " (%u vs %u)", call, tdb->file->locker, getpid());
  59         }
  60         return false;
  61 }
  62
  63 int tdb_fcntl_lock(int fd, int rw, off_t off, off_t len, bool waitflag,
  64                    void *unused)
  65 {
  66         struct flock fl;
  67         int ret;
  68
  69         do {
  70                 fl.l_type = rw;
  71                 fl.l_whence = SEEK_SET;
  72                 fl.l_start = off;
  73                 fl.l_len = len;
  74
  75                 if (waitflag)
  76                         ret = fcntl(fd, F_SETLKW, &fl);
  77                 else
  78                         ret = fcntl(fd, F_SETLK, &fl);
  79         } while (ret != 0 && errno == EINTR);
  80         return ret;
  81 }
  82
  83 int tdb_fcntl_unlock(int fd, int rw, off_t off, off_t len, void *unused)
  84 {
  85         struct flock fl;
  86         int ret;
  87
  88         do {
  89                 fl.l_type = F_UNLCK;
  90                 fl.l_whence = SEEK_SET;
  91                 fl.l_start = off;
  92                 fl.l_len = len;
  93
  94                 ret = fcntl(fd, F_SETLKW, &fl);
  95         } while (ret != 0 && errno == EINTR);
  96         return ret;
  97 }
  98
  99 static int lock(struct tdb_context *tdb,
 100                       int rw, off_t off, off_t len, bool waitflag)
 101 {
 102         if (tdb->file->allrecord_lock.count == 0
 103             && tdb->file->num_lockrecs == 0) {
 104                 tdb->file->locker = getpid();
 105         }
 106
 107         add_stat(tdb, lock_lowlevel, 1);
 108         if (!waitflag)
 109                 add_stat(tdb, lock_nonblock, 1);
 110         return tdb->lock_fn(tdb->file->fd, rw, off, len, waitflag,
 111                             tdb->lock_data);
 112 }
 113
 114 static int unlock(struct tdb_context *tdb, int rw, off_t off, off_t len)
 115 {
 116 #if 0 /* Check they matched up locks and unlocks correctly. */
 117         char line[80];
 118         FILE *locks;
 119         bool found = false;
 120
 121         locks = fopen("/proc/locks", "r");
 122
 123         while (fgets(line, 80, locks)) {
 124                 char *p;
 125                 int type, start, l;
 126
 127                 /* eg. 1: FLOCK  ADVISORY  WRITE 2440 08:01:2180826 0 EOF */
 128                 p = strchr(line, ':') + 1;
 129                 if (strncmp(p, " POSIX  ADVISORY  ", strlen(" POSIX  ADVISORY  ")))
 130                         continue;
 131                 p += strlen(" FLOCK  ADVISORY  ");
 132                 if (strncmp(p, "READ  ", strlen("READ  ")) == 0)
 133                         type = F_RDLCK;
 134                 else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0)
 135                         type = F_WRLCK;
 136                 else
 137                         abort();
 138                 p += 6;
 139                 if (atoi(p) != getpid())
 140                         continue;
 141                 p = strchr(strchr(p, ' ') + 1, ' ') + 1;
 142                 start = atoi(p);
 143                 p = strchr(p, ' ') + 1;
 144                 if (strncmp(p, "EOF", 3) == 0)
 145                         l = 0;
 146                 else
 147                         l = atoi(p) - start + 1;
 148
 149                 if (off == start) {
 150                         if (len != l) {
 151                                 fprintf(stderr, "Len %u should be %u: %s",
 152                                         (int)len, l, line);
 153                                 abort();
 154                         }
 155                         if (type != rw) {
 156                                 fprintf(stderr, "Type %s wrong: %s",
 157                                         rw == F_RDLCK ? "READ" : "WRITE", line);
 158                                 abort();
 159                         }
 160                         found = true;
 161                         break;
 162                 }
 163         }
 164
 165         if (!found) {
 166                 fprintf(stderr, "Unlock on %u@%u not found!",
 167                         (int)off, (int)len);
 168                 abort();
 169         }
 170
 171         fclose(locks);
 172 #endif
 173
 174         return tdb->unlock_fn(tdb->file->fd, rw, off, len, tdb->lock_data);
 175 }
 176
 177 /* a byte range locking function - return 0 on success
 178    this functions locks len bytes at the specified offset.
 179
 180    note that a len of zero means lock to end of file
 181 */
 182 static enum TDB_ERROR tdb_brlock(struct tdb_context *tdb,
 183                                  int rw_type, tdb_off_t offset, tdb_off_t len,
 184                                  enum tdb_lock_flags flags)
 185 {
 186         int ret;
 187
 188         if (tdb->flags & TDB_NOLOCK) {
 189                 return TDB_SUCCESS;
 190         }
 191
 192         if (rw_type == F_WRLCK && tdb->read_only) {
 193                 return tdb_logerr(tdb, TDB_ERR_RDONLY, TDB_LOG_USE_ERROR,
 194                                   "Write lock attempted on read-only database");
 195         }
 196
 197         /* A 32 bit system cannot open a 64-bit file, but it could have
 198          * expanded since then: check here. */
 199         if ((size_t)(offset + len) != offset + len) {
 200                 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 201                                   "tdb_brlock: lock on giant offset %llu",
 202                                   (long long)(offset + len));
 203         }
 204
 205         ret = lock(tdb, rw_type, offset, len, flags & TDB_LOCK_WAIT);
 206         if (ret != 0) {
 207                 /* Generic lock error. errno set by fcntl.
 208                  * EAGAIN is an expected return from non-blocking
 209                  * locks. */
 210                 if (!(flags & TDB_LOCK_PROBE)
 211                     && (errno != EAGAIN && errno != EINTR)) {
 212                         tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 213                                    "tdb_brlock failed (fd=%d) at"
 214                                    " offset %zu rw_type=%d flags=%d len=%zu:"
 215                                    " %s",
 216                                    tdb->file->fd, (size_t)offset, rw_type,
 217                                    flags, (size_t)len, strerror(errno));
 218                 }
 219                 return TDB_ERR_LOCK;
 220         }
 221         return TDB_SUCCESS;
 222 }
 223
 224 static enum TDB_ERROR tdb_brunlock(struct tdb_context *tdb,
 225                                    int rw_type, tdb_off_t offset, size_t len)
 226 {
 227         int ret;
 228
 229         if (tdb->flags & TDB_NOLOCK) {
 230                 return TDB_SUCCESS;
 231         }
 232
 233         ret = unlock(tdb, rw_type, offset, len);
 234
 235         /* If we fail, *then* we verify that we owned the lock.  If not, ok. */
 236         if (ret == -1 && check_lock_pid(tdb, "tdb_brunlock", false)) {
 237                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 238                                   "tdb_brunlock failed (fd=%d) at offset %zu"
 239                                   " rw_type=%d len=%zu: %s",
 240                                   tdb->file->fd, (size_t)offset, rw_type,
 241                                   (size_t)len, strerror(errno));
 242         }
 243         return TDB_SUCCESS;
 244 }
 245
 246 /*
 247   upgrade a read lock to a write lock. This needs to be handled in a
 248   special way as some OSes (such as solaris) have too conservative
 249   deadlock detection and claim a deadlock when progress can be
 250   made. For those OSes we may loop for a while.
 251 */
 252 enum TDB_ERROR tdb_allrecord_upgrade(struct tdb_context *tdb)
 253 {
 254         int count = 1000;
 255
 256         if (!check_lock_pid(tdb, "tdb_transaction_prepare_commit", true))
 257                 return TDB_ERR_LOCK;
 258
 259         if (tdb->file->allrecord_lock.count != 1) {
 260                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 261                                   "tdb_allrecord_upgrade failed:"
 262                                   " count %u too high",
 263                                   tdb->file->allrecord_lock.count);
 264         }
 265
 266         if (tdb->file->allrecord_lock.off != 1) {
 267                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 268                                   "tdb_allrecord_upgrade failed:"
 269                                   " already upgraded?");
 270         }
 271
 272         if (tdb->file->allrecord_lock.owner != tdb) {
 273                 return owner_conflict(tdb, "tdb_allrecord_upgrade");
 274         }
 275
 276         while (count--) {
 277                 struct timeval tv;
 278                 if (tdb_brlock(tdb, F_WRLCK,
 279                                TDB_HASH_LOCK_START, 0,
 280                                TDB_LOCK_WAIT|TDB_LOCK_PROBE) == TDB_SUCCESS) {
 281                         tdb->file->allrecord_lock.ltype = F_WRLCK;
 282                         tdb->file->allrecord_lock.off = 0;
 283                         return TDB_SUCCESS;
 284                 }
 285                 if (errno != EDEADLK) {
 286                         break;
 287                 }
 288                 /* sleep for as short a time as we can - more portable than usleep() */
 289                 tv.tv_sec = 0;
 290                 tv.tv_usec = 1;
 291                 select(0, NULL, NULL, NULL, &tv);
 292         }
 293
 294         if (errno != EAGAIN && errno != EINTR)
 295                 tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 296                            "tdb_allrecord_upgrade failed");
 297         return TDB_ERR_LOCK;
 298 }
 299
 300 static struct tdb_lock *find_nestlock(struct tdb_context *tdb, tdb_off_t offset,
 301                                       const struct tdb_context *owner)
 302 {
 303         unsigned int i;
 304
 305         for (i=0; i<tdb->file->num_lockrecs; i++) {
 306                 if (tdb->file->lockrecs[i].off == offset) {
 307                         if (owner && tdb->file->lockrecs[i].owner != owner)
 308                                 return NULL;
 309                         return &tdb->file->lockrecs[i];
 310                 }
 311         }
 312         return NULL;
 313 }
 314
 315 enum TDB_ERROR tdb_lock_and_recover(struct tdb_context *tdb)
 316 {
 317         enum TDB_ERROR ecode;
 318
 319         if (!check_lock_pid(tdb, "tdb_transaction_prepare_commit", true))
 320                 return TDB_ERR_LOCK;
 321
 322         ecode = tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK,
 323                                    false);
 324         if (ecode != TDB_SUCCESS) {
 325                 return ecode;
 326         }
 327
 328         ecode = tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK);
 329         if (ecode != TDB_SUCCESS) {
 330                 tdb_allrecord_unlock(tdb, F_WRLCK);
 331                 return ecode;
 332         }
 333         ecode = tdb_transaction_recover(tdb);
 334         tdb_unlock_open(tdb);
 335         tdb_allrecord_unlock(tdb, F_WRLCK);
 336
 337         return ecode;
 338 }
 339
 340 /* lock an offset in the database. */
 341 static enum TDB_ERROR tdb_nest_lock(struct tdb_context *tdb,
 342                                     tdb_off_t offset, int ltype,
 343                                     enum tdb_lock_flags flags)
 344 {
 345         struct tdb_lock *new_lck;
 346         enum TDB_ERROR ecode;
 347
 348         if (offset > (TDB_HASH_LOCK_START + TDB_HASH_LOCK_RANGE
 349                       + tdb->file->map_size / 8)) {
 350                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 351                                   "tdb_nest_lock: invalid offset %zu ltype=%d",
 352                                   (size_t)offset, ltype);
 353         }
 354
 355         if (tdb->flags & TDB_NOLOCK)
 356                 return TDB_SUCCESS;
 357
 358         if (!check_lock_pid(tdb, "tdb_nest_lock", true)) {
 359                 return TDB_ERR_LOCK;
 360         }
 361
 362         add_stat(tdb, locks, 1);
 363
 364         new_lck = find_nestlock(tdb, offset, NULL);
 365         if (new_lck) {
 366                 if (new_lck->owner != tdb) {
 367                         return owner_conflict(tdb, "tdb_nest_lock");
 368                 }
 369
 370                 if (new_lck->ltype == F_RDLCK && ltype == F_WRLCK) {
 371                         return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 372                                           "tdb_nest_lock:"
 373                                           " offset %zu has read lock",
 374                                           (size_t)offset);
 375                 }
 376                 /* Just increment the struct, posix locks don't stack. */
 377                 new_lck->count++;
 378                 return TDB_SUCCESS;
 379         }
 380
 381         if (tdb->file->num_lockrecs
 382             && offset >= TDB_HASH_LOCK_START
 383             && offset < TDB_HASH_LOCK_START + TDB_HASH_LOCK_RANGE) {
 384                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 385                                   "tdb_nest_lock: already have a hash lock?");
 386         }
 387
 388         new_lck = (struct tdb_lock *)realloc(
 389                 tdb->file->lockrecs,
 390                 sizeof(*tdb->file->lockrecs) * (tdb->file->num_lockrecs+1));
 391         if (new_lck == NULL) {
 392                 return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 393                                   "tdb_nest_lock:"
 394                                   " unable to allocate %zu lock struct",
 395                                   tdb->file->num_lockrecs + 1);
 396         }
 397         tdb->file->lockrecs = new_lck;
 398
 399         /* Since fcntl locks don't nest, we do a lock for the first one,
 400            and simply bump the count for future ones */
 401         ecode = tdb_brlock(tdb, ltype, offset, 1, flags);
 402         if (ecode != TDB_SUCCESS) {
 403                 return ecode;
 404         }
 405
 406         /* First time we grab a lock, perhaps someone died in commit? */
 407         if (!(flags & TDB_LOCK_NOCHECK)
 408             && tdb->file->num_lockrecs == 0) {
 409                 tdb_bool_err berr = tdb_needs_recovery(tdb);
 410                 if (berr != false) {
 411                         tdb_brunlock(tdb, ltype, offset, 1);
 412
 413                         if (berr < 0)
 414                                 return berr;
 415                         ecode = tdb_lock_and_recover(tdb);
 416                         if (ecode == TDB_SUCCESS) {
 417                                 ecode = tdb_brlock(tdb, ltype, offset, 1,
 418                                                    flags);
 419                         }
 420                         if (ecode != TDB_SUCCESS) {
 421                                 return ecode;
 422                         }
 423                 }
 424         }
 425
 426         tdb->file->lockrecs[tdb->file->num_lockrecs].owner = tdb;
 427         tdb->file->lockrecs[tdb->file->num_lockrecs].off = offset;
 428         tdb->file->lockrecs[tdb->file->num_lockrecs].count = 1;
 429         tdb->file->lockrecs[tdb->file->num_lockrecs].ltype = ltype;
 430         tdb->file->num_lockrecs++;
 431
 432         return TDB_SUCCESS;
 433 }
 434
 435 static enum TDB_ERROR tdb_nest_unlock(struct tdb_context *tdb,
 436                                       tdb_off_t off, int ltype)
 437 {
 438         struct tdb_lock *lck;
 439         enum TDB_ERROR ecode;
 440
 441         if (tdb->flags & TDB_NOLOCK)
 442                 return TDB_SUCCESS;
 443
 444         lck = find_nestlock(tdb, off, tdb);
 445         if ((lck == NULL) || (lck->count == 0)) {
 446                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 447                                   "tdb_nest_unlock: no lock for %zu",
 448                                   (size_t)off);
 449         }
 450
 451         if (lck->count > 1) {
 452                 lck->count--;
 453                 return TDB_SUCCESS;
 454         }
 455
 456         /*
 457          * This lock has count==1 left, so we need to unlock it in the
 458          * kernel. We don't bother with decrementing the in-memory array
 459          * element, we're about to overwrite it with the last array element
 460          * anyway.
 461          */
 462         ecode = tdb_brunlock(tdb, ltype, off, 1);
 463
 464         /*
 465          * Shrink the array by overwriting the element just unlocked with the
 466          * last array element.
 467          */
 468         *lck = tdb->file->lockrecs[--tdb->file->num_lockrecs];
 469
 470         return ecode;
 471 }
 472
 473 /*
 474   get the transaction lock
 475  */
 476 enum TDB_ERROR tdb_transaction_lock(struct tdb_context *tdb, int ltype)
 477 {
 478         return tdb_nest_lock(tdb, TDB_TRANSACTION_LOCK, ltype, TDB_LOCK_WAIT);
 479 }
 480
 481 /*
 482   release the transaction lock
 483  */
 484 void tdb_transaction_unlock(struct tdb_context *tdb, int ltype)
 485 {
 486         tdb_nest_unlock(tdb, TDB_TRANSACTION_LOCK, ltype);
 487 }
 488
 489 /* We only need to lock individual bytes, but Linux merges consecutive locks
 490  * so we lock in contiguous ranges. */
 491 static enum TDB_ERROR tdb_lock_gradual(struct tdb_context *tdb,
 492                                        int ltype, enum tdb_lock_flags flags,
 493                                        tdb_off_t off, tdb_off_t len)
 494 {
 495         enum TDB_ERROR ecode;
 496         enum tdb_lock_flags nb_flags = (flags & ~TDB_LOCK_WAIT);
 497
 498         if (len <= 1) {
 499                 /* 0 would mean to end-of-file... */
 500                 assert(len != 0);
 501                 /* Single hash.  Just do blocking lock. */
 502                 return tdb_brlock(tdb, ltype, off, len, flags);
 503         }
 504
 505         /* First we try non-blocking. */
 506         if (tdb_brlock(tdb, ltype, off, len, nb_flags) == TDB_SUCCESS) {
 507                 return TDB_SUCCESS;
 508         }
 509
 510         /* Try locking first half, then second. */
 511         ecode = tdb_lock_gradual(tdb, ltype, flags, off, len / 2);
 512         if (ecode != TDB_SUCCESS)
 513                 return ecode;
 514
 515         ecode = tdb_lock_gradual(tdb, ltype, flags,
 516                                  off + len / 2, len - len / 2);
 517         if (ecode != TDB_SUCCESS) {
 518                 tdb_brunlock(tdb, ltype, off, len / 2);
 519         }
 520         return ecode;
 521 }
 522
 523 /* lock/unlock entire database.  It can only be upgradable if you have some
 524  * other way of guaranteeing exclusivity (ie. transaction write lock). */
 525 enum TDB_ERROR tdb_allrecord_lock(struct tdb_context *tdb, int ltype,
 526                                   enum tdb_lock_flags flags, bool upgradable)
 527 {
 528         enum TDB_ERROR ecode;
 529         tdb_bool_err berr;
 530
 531         if (tdb->flags & TDB_NOLOCK)
 532                 return TDB_SUCCESS;
 533
 534         if (!check_lock_pid(tdb, "tdb_allrecord_lock", true)) {
 535                 return TDB_ERR_LOCK;
 536         }
 537
 538         if (tdb->file->allrecord_lock.count) {
 539                 if (tdb->file->allrecord_lock.owner != tdb) {
 540                         return owner_conflict(tdb, "tdb_allrecord_lock");
 541                 }
 542
 543                 if (ltype == F_RDLCK
 544                     || tdb->file->allrecord_lock.ltype == F_WRLCK) {
 545                         tdb->file->allrecord_lock.count++;
 546                         return TDB_SUCCESS;
 547                 }
 548
 549                 /* a global lock of a different type exists */
 550                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
 551                                   "tdb_allrecord_lock: already have %s lock",
 552                                   tdb->file->allrecord_lock.ltype == F_RDLCK
 553                                   ? "read" : "write");
 554         }
 555
 556         if (tdb_has_hash_locks(tdb)) {
 557                 /* can't combine global and chain locks */
 558                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
 559                                   "tdb_allrecord_lock:"
 560                                   " already have chain lock");
 561         }
 562
 563         if (upgradable && ltype != F_RDLCK) {
 564                 /* tdb error: you can't upgrade a write lock! */
 565                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 566                                   "tdb_allrecord_lock:"
 567                                   " can't upgrade a write lock");
 568         }
 569
 570         add_stat(tdb, locks, 1);
 571 again:
 572         /* Lock hashes, gradually. */
 573         ecode = tdb_lock_gradual(tdb, ltype, flags, TDB_HASH_LOCK_START,
 574                                  TDB_HASH_LOCK_RANGE);
 575         if (ecode != TDB_SUCCESS)
 576                 return ecode;
 577
 578         /* Lock free tables: there to end of file. */
 579         ecode = tdb_brlock(tdb, ltype,
 580                            TDB_HASH_LOCK_START + TDB_HASH_LOCK_RANGE,
 581                            0, flags);
 582         if (ecode != TDB_SUCCESS) {
 583                 tdb_brunlock(tdb, ltype, TDB_HASH_LOCK_START,
 584                              TDB_HASH_LOCK_RANGE);
 585                 return ecode;
 586         }
 587
 588         tdb->file->allrecord_lock.owner = tdb;
 589         tdb->file->allrecord_lock.count = 1;
 590         /* If it's upgradable, it's actually exclusive so we can treat
 591          * it as a write lock. */
 592         tdb->file->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
 593         tdb->file->allrecord_lock.off = upgradable;
 594
 595         /* Now check for needing recovery. */
 596         if (flags & TDB_LOCK_NOCHECK)
 597                 return TDB_SUCCESS;
 598
 599         berr = tdb_needs_recovery(tdb);
 600         if (likely(berr == false))
 601                 return TDB_SUCCESS;
 602
 603         tdb_allrecord_unlock(tdb, ltype);
 604         if (berr < 0)
 605                 return berr;
 606         ecode = tdb_lock_and_recover(tdb);
 607         if (ecode != TDB_SUCCESS) {
 608                 return ecode;
 609         }
 610         goto again;
 611 }
 612
 613 enum TDB_ERROR tdb_lock_open(struct tdb_context *tdb, enum tdb_lock_flags flags)
 614 {
 615         return tdb_nest_lock(tdb, TDB_OPEN_LOCK, F_WRLCK, flags);
 616 }
 617
 618 void tdb_unlock_open(struct tdb_context *tdb)
 619 {
 620         tdb_nest_unlock(tdb, TDB_OPEN_LOCK, F_WRLCK);
 621 }
 622
 623 bool tdb_has_open_lock(struct tdb_context *tdb)
 624 {
 625         return !(tdb->flags & TDB_NOLOCK)
 626                 && find_nestlock(tdb, TDB_OPEN_LOCK, tdb) != NULL;
 627 }
 628
 629 enum TDB_ERROR tdb_lock_expand(struct tdb_context *tdb, int ltype)
 630 {
 631         /* Lock doesn't protect data, so don't check (we recurse if we do!) */
 632         return tdb_nest_lock(tdb, TDB_EXPANSION_LOCK, ltype,
 633                              TDB_LOCK_WAIT | TDB_LOCK_NOCHECK);
 634 }
 635
 636 void tdb_unlock_expand(struct tdb_context *tdb, int ltype)
 637 {
 638         tdb_nest_unlock(tdb, TDB_EXPANSION_LOCK, ltype);
 639 }
 640
 641 /* unlock entire db */
 642 void tdb_allrecord_unlock(struct tdb_context *tdb, int ltype)
 643 {
 644         if (tdb->flags & TDB_NOLOCK)
 645                 return;
 646
 647         if (tdb->file->allrecord_lock.count == 0) {
 648                 tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
 649                            "tdb_allrecord_unlock: not locked!");
 650                 return;
 651         }
 652
 653         if (tdb->file->allrecord_lock.owner != tdb) {
 654                 tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
 655                            "tdb_allrecord_unlock: not locked by us!");
 656                 return;
 657         }
 658
 659         /* Upgradable locks are marked as write locks. */
 660         if (tdb->file->allrecord_lock.ltype != ltype
 661             && (!tdb->file->allrecord_lock.off || ltype != F_RDLCK)) {
 662                 tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 663                            "tdb_allrecord_unlock: have %s lock",
 664                            tdb->file->allrecord_lock.ltype == F_RDLCK
 665                            ? "read" : "write");
 666                 return;
 667         }
 668
 669         if (tdb->file->allrecord_lock.count > 1) {
 670                 tdb->file->allrecord_lock.count--;
 671                 return;
 672         }
 673
 674         tdb->file->allrecord_lock.count = 0;
 675         tdb->file->allrecord_lock.ltype = 0;
 676
 677         tdb_brunlock(tdb, ltype, TDB_HASH_LOCK_START, 0);
 678 }
 679
 680 bool tdb_has_expansion_lock(struct tdb_context *tdb)
 681 {
 682         return find_nestlock(tdb, TDB_EXPANSION_LOCK, tdb) != NULL;
 683 }
 684
 685 bool tdb_has_hash_locks(struct tdb_context *tdb)
 686 {
 687         unsigned int i;
 688
 689         for (i=0; i<tdb->file->num_lockrecs; i++) {
 690                 if (tdb->file->lockrecs[i].off >= TDB_HASH_LOCK_START
 691                     && tdb->file->lockrecs[i].off < (TDB_HASH_LOCK_START
 692                                                      + TDB_HASH_LOCK_RANGE))
 693                         return true;
 694         }
 695         return false;
 696 }
 697
 698 static bool tdb_has_free_lock(struct tdb_context *tdb)
 699 {
 700         unsigned int i;
 701
 702         if (tdb->flags & TDB_NOLOCK)
 703                 return false;
 704
 705         for (i=0; i<tdb->file->num_lockrecs; i++) {
 706                 if (tdb->file->lockrecs[i].off
 707                     > TDB_HASH_LOCK_START + TDB_HASH_LOCK_RANGE)
 708                         return true;
 709         }
 710         return false;
 711 }
 712
 713 enum TDB_ERROR tdb_lock_hashes(struct tdb_context *tdb,
 714                                tdb_off_t hash_lock,
 715                                tdb_len_t hash_range,
 716                                int ltype, enum tdb_lock_flags waitflag)
 717 {
 718         /* FIXME: Do this properly, using hlock_range */
 719         unsigned l = TDB_HASH_LOCK_START
 720                 + (hash_lock >> (64 - TDB_HASH_LOCK_RANGE_BITS));
 721
 722         /* a allrecord lock allows us to avoid per chain locks */
 723         if (tdb->file->allrecord_lock.count) {
 724                 if (!check_lock_pid(tdb, "tdb_lock_hashes", true))
 725                         return TDB_ERR_LOCK;
 726
 727                 if (tdb->file->allrecord_lock.owner != tdb)
 728                         return owner_conflict(tdb, "tdb_lock_hashes");
 729                 if (ltype == tdb->file->allrecord_lock.ltype
 730                     || ltype == F_RDLCK) {
 731                         return TDB_SUCCESS;
 732                 }
 733
 734                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
 735                                   "tdb_lock_hashes:"
 736                                   " already have %s allrecordlock",
 737                                   tdb->file->allrecord_lock.ltype == F_RDLCK
 738                                   ? "read" : "write");
 739         }
 740
 741         if (tdb_has_free_lock(tdb)) {
 742                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 743                                   "tdb_lock_hashes: already have free lock");
 744         }
 745
 746         if (tdb_has_expansion_lock(tdb)) {
 747                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 748                                   "tdb_lock_hashes:"
 749                                   " already have expansion lock");
 750         }
 751
 752         return tdb_nest_lock(tdb, l, ltype, waitflag);
 753 }
 754
 755 enum TDB_ERROR tdb_unlock_hashes(struct tdb_context *tdb,
 756                                  tdb_off_t hash_lock,
 757                                  tdb_len_t hash_range, int ltype)
 758 {
 759         unsigned l = TDB_HASH_LOCK_START
 760                 + (hash_lock >> (64 - TDB_HASH_LOCK_RANGE_BITS));
 761
 762         if (tdb->flags & TDB_NOLOCK)
 763                 return 0;
 764
 765         /* a allrecord lock allows us to avoid per chain locks */
 766         if (tdb->file->allrecord_lock.count) {
 767                 if (tdb->file->allrecord_lock.ltype == F_RDLCK
 768                     && ltype == F_WRLCK) {
 769                         return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 770                                           "tdb_unlock_hashes RO allrecord!");
 771                 }
 772                 return TDB_SUCCESS;
 773         }
 774
 775         return tdb_nest_unlock(tdb, l, ltype);
 776 }
 777
 778 /* Hash locks use TDB_HASH_LOCK_START + the next 30 bits.
 779  * Then we begin; bucket offsets are sizeof(tdb_len_t) apart, so we divide.
 780  * The result is that on 32 bit systems we don't use lock values > 2^31 on
 781  * files that are less than 4GB.
 782  */
 783 static tdb_off_t free_lock_off(tdb_off_t b_off)
 784 {
 785         return TDB_HASH_LOCK_START + TDB_HASH_LOCK_RANGE
 786                 + b_off / sizeof(tdb_off_t);
 787 }
 788
 789 enum TDB_ERROR tdb_lock_free_bucket(struct tdb_context *tdb, tdb_off_t b_off,
 790                                     enum tdb_lock_flags waitflag)
 791 {
 792         assert(b_off >= sizeof(struct tdb_header));
 793
 794         if (tdb->flags & TDB_NOLOCK)
 795                 return 0;
 796
 797         /* a allrecord lock allows us to avoid per chain locks */
 798         if (tdb->file->allrecord_lock.count) {
 799                 if (!check_lock_pid(tdb, "tdb_lock_free_bucket", true))
 800                         return TDB_ERR_LOCK;
 801
 802                 if (tdb->file->allrecord_lock.ltype == F_WRLCK)
 803                         return 0;
 804                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 805                                   "tdb_lock_free_bucket with"
 806                                   " read-only allrecordlock!");
 807         }
 808
 809 #if 0 /* FIXME */
 810         if (tdb_has_expansion_lock(tdb)) {
 811                 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_ERROR,
 812                                   "tdb_lock_free_bucket:"
 813                                   " already have expansion lock");
 814         }
 815 #endif
 816
 817         return tdb_nest_lock(tdb, free_lock_off(b_off), F_WRLCK, waitflag);
 818 }
 819
 820 void tdb_unlock_free_bucket(struct tdb_context *tdb, tdb_off_t b_off)
 821 {
 822         if (tdb->file->allrecord_lock.count)
 823                 return;
 824
 825         tdb_nest_unlock(tdb, free_lock_off(b_off), F_WRLCK);
 826 }
 827
 828 enum TDB_ERROR tdb_lockall(struct tdb_context *tdb)
 829 {
 830         return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false);
 831 }
 832
 833 void tdb_unlockall(struct tdb_context *tdb)
 834 {
 835         tdb_allrecord_unlock(tdb, F_WRLCK);
 836 }
 837
 838 enum TDB_ERROR tdb_lockall_read(struct tdb_context *tdb)
 839 {
 840         return tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, false);
 841 }
 842
 843 void tdb_unlockall_read(struct tdb_context *tdb)
 844 {
 845         tdb_allrecord_unlock(tdb, F_RDLCK);
 846 }
 847
 848 void tdb_lock_cleanup(struct tdb_context *tdb)
 849 {
 850         unsigned int i;
 851
 852         while (tdb->file->allrecord_lock.count
 853                && tdb->file->allrecord_lock.owner == tdb) {
 854                 tdb_allrecord_unlock(tdb, tdb->file->allrecord_lock.ltype);
 855         }
 856
 857         for (i=0; i<tdb->file->num_lockrecs; i++) {
 858                 if (tdb->file->lockrecs[i].owner == tdb) {
 859                         tdb_nest_unlock(tdb,
 860                                         tdb->file->lockrecs[i].off,
 861                                         tdb->file->lockrecs[i].ltype);
 862                         i--;
 863                 }
 864         }
 865 }