2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 1999-2005
7 Copyright (C) Paul `Rusty' Russell 2000
8 Copyright (C) Jeremy Allison 2000-2003
10 ** NOTE! The following LGPL license applies to the tdb
11 ** library. This does NOT imply that all of Samba is released
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.
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.
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/>.
28 #include "tdb_private.h"
30 _PUBLIC_ void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr)
32 tdb->interrupt_sig_ptr = ptr;
35 static int fcntl_lock(struct tdb_context *tdb,
36 int rw, off_t off, off_t len, bool waitflag)
41 #ifdef USE_TDB_MUTEX_LOCKING
44 if (tdb_mutex_lock(tdb, rw, off, len, waitflag, &ret)) {
51 fl.l_whence = SEEK_SET;
56 cmd = waitflag ? F_SETLKW : F_SETLK;
58 return fcntl(tdb->fd, cmd, &fl);
61 static int fcntl_unlock(struct tdb_context *tdb, int rw, off_t off, off_t len)
64 #if 0 /* Check they matched up locks and unlocks correctly. */
69 locks = fopen("/proc/locks", "r");
71 while (fgets(line, 80, locks)) {
75 /* eg. 1: FLOCK ADVISORY WRITE 2440 08:01:2180826 0 EOF */
76 p = strchr(line, ':') + 1;
77 if (strncmp(p, " POSIX ADVISORY ", strlen(" POSIX ADVISORY ")))
79 p += strlen(" FLOCK ADVISORY ");
80 if (strncmp(p, "READ ", strlen("READ ")) == 0)
82 else if (strncmp(p, "WRITE ", strlen("WRITE ")) == 0)
87 if (atoi(p) != getpid())
89 p = strchr(strchr(p, ' ') + 1, ' ') + 1;
91 p = strchr(p, ' ') + 1;
92 if (strncmp(p, "EOF", 3) == 0)
95 l = atoi(p) - start + 1;
99 fprintf(stderr, "Len %u should be %u: %s",
104 fprintf(stderr, "Type %s wrong: %s",
105 rw == F_RDLCK ? "READ" : "WRITE", line);
114 fprintf(stderr, "Unlock on %u@%u not found!\n",
122 #ifdef USE_TDB_MUTEX_LOCKING
125 if (tdb_mutex_unlock(tdb, rw, off, len, &ret)) {
132 fl.l_whence = SEEK_SET;
137 return fcntl(tdb->fd, F_SETLKW, &fl);
141 * Calculate the lock offset for a list
143 * list -1 is the freelist, otherwise a hash chain.
145 * Note that we consistently (but without real reason) lock hash chains at an
146 * offset that is 4 bytes below the real offset of the corresponding list head
149 * This is the memory layout of the hashchain array:
151 * FREELIST_TOP + 0 = freelist
152 * FREELIST_TOP + 4 = hashtbale list 0
153 * FREELIST_TOP + 8 = hashtbale list 1
156 * Otoh lock_offset computes:
158 * freelist = FREELIST_TOP - 4
159 * list 0 = FREELIST_TOP + 0
160 * list 1 = FREELIST_TOP + 4
163 * Unfortunately we can't change this calculation in order to align the locking
164 * offset with the memory layout, as that would make the locking incompatible
165 * between different tdb versions.
167 static tdb_off_t lock_offset(int list)
169 return FREELIST_TOP + 4*list;
172 /* a byte range locking function - return 0 on success
173 this functions locks/unlocks "len" byte at the specified offset.
175 On error, errno is also set so that errors are passed back properly
178 note that a len of zero means lock to end of file
180 int tdb_brlock(struct tdb_context *tdb,
181 int rw_type, tdb_off_t offset, size_t len,
182 enum tdb_lock_flags flags)
186 if (tdb->flags & TDB_NOLOCK) {
190 if (flags & TDB_LOCK_MARK_ONLY) {
194 if ((rw_type == F_WRLCK) && (tdb->read_only || tdb->traverse_read)) {
195 tdb->ecode = TDB_ERR_RDONLY;
200 ret = fcntl_lock(tdb, rw_type, offset, len,
201 flags & TDB_LOCK_WAIT);
202 /* Check for a sigalarm break. */
203 if (ret == -1 && errno == EINTR &&
204 tdb->interrupt_sig_ptr &&
205 *tdb->interrupt_sig_ptr) {
208 } while (ret == -1 && errno == EINTR);
211 tdb->ecode = TDB_ERR_LOCK;
212 /* Generic lock error. errno set by fcntl.
213 * EAGAIN is an expected return from non-blocking
215 if (!(flags & TDB_LOCK_PROBE) && errno != EAGAIN) {
216 TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brlock failed (fd=%d) at offset %u rw_type=%d flags=%d len=%zu\n",
217 tdb->fd, offset, rw_type, flags, len));
224 int tdb_brunlock(struct tdb_context *tdb,
225 int rw_type, tdb_off_t offset, size_t len)
229 if (tdb->flags & TDB_NOLOCK) {
234 ret = fcntl_unlock(tdb, rw_type, offset, len);
235 } while (ret == -1 && errno == EINTR);
238 TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_brunlock failed (fd=%d) at offset %u rw_type=%u len=%zu\n",
239 tdb->fd, offset, rw_type, len));
245 * Do a tdb_brlock in a loop. Some OSes (such as solaris) have too
246 * conservative deadlock detection and claim a deadlock when progress can be
247 * made. For those OSes we may loop for a while.
250 static int tdb_brlock_retry(struct tdb_context *tdb,
251 int rw_type, tdb_off_t offset, size_t len,
252 enum tdb_lock_flags flags)
260 ret = tdb_brlock(tdb, rw_type, offset, len, flags);
264 if (errno != EDEADLK) {
267 /* sleep for as short a time as we can - more portable than usleep() */
270 select(0, NULL, NULL, NULL, &tv);
276 upgrade a read lock to a write lock.
278 int tdb_allrecord_upgrade(struct tdb_context *tdb)
282 if (tdb->allrecord_lock.count != 1) {
283 TDB_LOG((tdb, TDB_DEBUG_ERROR,
284 "tdb_allrecord_upgrade failed: count %u too high\n",
285 tdb->allrecord_lock.count));
286 tdb->ecode = TDB_ERR_LOCK;
290 if (tdb->allrecord_lock.off != 1) {
291 TDB_LOG((tdb, TDB_DEBUG_ERROR,
292 "tdb_allrecord_upgrade failed: already upgraded?\n"));
293 tdb->ecode = TDB_ERR_LOCK;
297 if (tdb_have_mutexes(tdb)) {
298 ret = tdb_mutex_allrecord_upgrade(tdb);
302 ret = tdb_brlock_retry(tdb, F_WRLCK, lock_offset(tdb->hash_size),
303 0, TDB_LOCK_WAIT|TDB_LOCK_PROBE);
305 tdb_mutex_allrecord_downgrade(tdb);
308 ret = tdb_brlock_retry(tdb, F_WRLCK, FREELIST_TOP, 0,
309 TDB_LOCK_WAIT|TDB_LOCK_PROBE);
313 tdb->allrecord_lock.ltype = F_WRLCK;
314 tdb->allrecord_lock.off = 0;
318 TDB_LOG((tdb, TDB_DEBUG_TRACE,"tdb_allrecord_upgrade failed\n"));
322 static struct tdb_lock_type *find_nestlock(struct tdb_context *tdb,
327 for (i=0; i<tdb->num_lockrecs; i++) {
328 if (tdb->lockrecs[i].off == offset) {
329 return &tdb->lockrecs[i];
335 /* lock an offset in the database. */
336 int tdb_nest_lock(struct tdb_context *tdb, uint32_t offset, int ltype,
337 enum tdb_lock_flags flags)
339 struct tdb_lock_type *new_lck;
341 if (offset >= lock_offset(tdb->hash_size)) {
342 tdb->ecode = TDB_ERR_LOCK;
343 TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_lock: invalid offset %u for ltype=%d\n",
347 if (tdb->flags & TDB_NOLOCK)
350 new_lck = find_nestlock(tdb, offset);
352 if ((new_lck->ltype == F_RDLCK) && (ltype == F_WRLCK)) {
353 if (!tdb_have_mutexes(tdb)) {
356 * Upgrade the underlying fcntl
357 * lock. Mutexes don't do readlocks,
358 * so this only applies to fcntl
361 ret = tdb_brlock(tdb, ltype, offset, 1, flags);
366 new_lck->ltype = F_WRLCK;
369 * Just increment the in-memory struct, posix locks
376 if (tdb->num_lockrecs == tdb->lockrecs_array_length) {
377 new_lck = (struct tdb_lock_type *)realloc(
379 sizeof(*tdb->lockrecs) * (tdb->num_lockrecs+1));
380 if (new_lck == NULL) {
384 tdb->lockrecs_array_length = tdb->num_lockrecs+1;
385 tdb->lockrecs = new_lck;
388 /* Since fcntl locks don't nest, we do a lock for the first one,
389 and simply bump the count for future ones */
390 if (tdb_brlock(tdb, ltype, offset, 1, flags)) {
394 new_lck = &tdb->lockrecs[tdb->num_lockrecs];
396 new_lck->off = offset;
398 new_lck->ltype = ltype;
404 static int tdb_lock_and_recover(struct tdb_context *tdb)
408 /* We need to match locking order in transaction commit. */
409 if (tdb_brlock(tdb, F_WRLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT)) {
413 if (tdb_brlock(tdb, F_WRLCK, OPEN_LOCK, 1, TDB_LOCK_WAIT)) {
414 tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0);
418 ret = tdb_transaction_recover(tdb);
420 tdb_brunlock(tdb, F_WRLCK, OPEN_LOCK, 1);
421 tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0);
426 static bool have_data_locks(const struct tdb_context *tdb)
430 for (i = 0; i < tdb->num_lockrecs; i++) {
431 if (tdb->lockrecs[i].off >= lock_offset(-1))
438 * A allrecord lock allows us to avoid per chain locks. Check if the allrecord
439 * lock is strong enough.
441 static int tdb_lock_covered_by_allrecord_lock(struct tdb_context *tdb,
444 if (ltype == F_RDLCK) {
446 * The allrecord_lock is equal (F_RDLCK) or stronger
452 if (tdb->allrecord_lock.ltype == F_RDLCK) {
454 * We ask for ltype==F_WRLCK, but the allrecord_lock
455 * is too weak. We can't upgrade here, so fail.
457 tdb->ecode = TDB_ERR_LOCK;
462 * Asking for F_WRLCK, allrecord is F_WRLCK as well. Pass.
467 static int tdb_lock_list(struct tdb_context *tdb, int list, int ltype,
468 enum tdb_lock_flags waitflag)
473 if (tdb->allrecord_lock.count) {
474 return tdb_lock_covered_by_allrecord_lock(tdb, ltype);
478 * Check for recoveries: Someone might have kill -9'ed a process
481 check = !have_data_locks(tdb);
482 ret = tdb_nest_lock(tdb, lock_offset(list), ltype, waitflag);
484 if (ret == 0 && check && tdb_needs_recovery(tdb)) {
485 tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
487 if (tdb_lock_and_recover(tdb) == -1) {
490 return tdb_lock_list(tdb, list, ltype, waitflag);
495 /* lock a list in the database. list -1 is the alloc list */
496 int tdb_lock(struct tdb_context *tdb, int list, int ltype)
500 ret = tdb_lock_list(tdb, list, ltype, TDB_LOCK_WAIT);
502 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_lock failed on list %d "
503 "ltype=%d (%s)\n", list, ltype, strerror(errno)));
508 /* lock a list in the database. list -1 is the alloc list. non-blocking lock */
509 _PUBLIC_ int tdb_lock_nonblock(struct tdb_context *tdb, int list, int ltype)
511 return tdb_lock_list(tdb, list, ltype, TDB_LOCK_NOWAIT);
515 int tdb_nest_unlock(struct tdb_context *tdb, uint32_t offset, int ltype,
519 struct tdb_lock_type *lck;
521 if (tdb->flags & TDB_NOLOCK)
525 if (offset >= lock_offset(tdb->hash_size)) {
526 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: offset %u invalid (%d)\n", offset, tdb->hash_size));
530 lck = find_nestlock(tdb, offset);
531 if ((lck == NULL) || (lck->count == 0)) {
532 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: count is 0\n"));
536 if (lck->count > 1) {
542 * This lock has count==1 left, so we need to unlock it in the
543 * kernel. We don't bother with decrementing the in-memory array
544 * element, we're about to overwrite it with the last array element
551 ret = tdb_brunlock(tdb, ltype, offset, 1);
555 * Shrink the array by overwriting the element just unlocked with the
556 * last array element.
558 *lck = tdb->lockrecs[--tdb->num_lockrecs];
561 * We don't bother with realloc when the array shrinks, but if we have
562 * a completely idle tdb we should get rid of the locked array.
566 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlock: An error occurred unlocking!\n"));
570 _PUBLIC_ int tdb_unlock(struct tdb_context *tdb, int list, int ltype)
572 /* a global lock allows us to avoid per chain locks */
573 if (tdb->allrecord_lock.count) {
574 return tdb_lock_covered_by_allrecord_lock(tdb, ltype);
577 return tdb_nest_unlock(tdb, lock_offset(list), ltype, false);
581 get the transaction lock
583 int tdb_transaction_lock(struct tdb_context *tdb, int ltype,
584 enum tdb_lock_flags lockflags)
586 return tdb_nest_lock(tdb, TRANSACTION_LOCK, ltype, lockflags);
590 release the transaction lock
592 int tdb_transaction_unlock(struct tdb_context *tdb, int ltype)
594 return tdb_nest_unlock(tdb, TRANSACTION_LOCK, ltype, false);
597 /* Returns 0 if all done, -1 if error, 1 if ok. */
598 static int tdb_allrecord_check(struct tdb_context *tdb, int ltype,
599 enum tdb_lock_flags flags, bool upgradable)
601 /* There are no locks on read-only dbs */
602 if (tdb->read_only || tdb->traverse_read) {
603 tdb->ecode = TDB_ERR_LOCK;
607 if (tdb->allrecord_lock.count &&
608 tdb->allrecord_lock.ltype == (uint32_t)ltype) {
609 tdb->allrecord_lock.count++;
613 if (tdb->allrecord_lock.count) {
614 /* a global lock of a different type exists */
615 tdb->ecode = TDB_ERR_LOCK;
619 if (tdb_have_extra_locks(tdb)) {
620 /* can't combine global and chain locks */
621 tdb->ecode = TDB_ERR_LOCK;
625 if (upgradable && ltype != F_RDLCK) {
626 /* tdb error: you can't upgrade a write lock! */
627 tdb->ecode = TDB_ERR_LOCK;
633 /* We only need to lock individual bytes, but Linux merges consecutive locks
634 * so we lock in contiguous ranges. */
635 static int tdb_chainlock_gradual(struct tdb_context *tdb,
636 int ltype, enum tdb_lock_flags flags,
637 size_t off, size_t len)
640 enum tdb_lock_flags nb_flags = (flags & ~TDB_LOCK_WAIT);
643 /* Single record. Just do blocking lock. */
644 return tdb_brlock(tdb, ltype, off, len, flags);
647 /* First we try non-blocking. */
648 ret = tdb_brlock(tdb, ltype, off, len, nb_flags);
653 /* Try locking first half, then second. */
654 ret = tdb_chainlock_gradual(tdb, ltype, flags, off, len / 2);
658 ret = tdb_chainlock_gradual(tdb, ltype, flags,
659 off + len / 2, len - len / 2);
661 tdb_brunlock(tdb, ltype, off, len / 2);
667 /* lock/unlock entire database. It can only be upgradable if you have some
668 * other way of guaranteeing exclusivity (ie. transaction write lock).
669 * We do the locking gradually to avoid being starved by smaller locks. */
670 int tdb_allrecord_lock(struct tdb_context *tdb, int ltype,
671 enum tdb_lock_flags flags, bool upgradable)
675 switch (tdb_allrecord_check(tdb, ltype, flags, upgradable)) {
682 /* We cover two kinds of locks:
683 * 1) Normal chain locks. Taken for almost all operations.
684 * 2) Individual records locks. Taken after normal or free
687 * It is (1) which cause the starvation problem, so we're only
688 * gradual for that. */
690 if (tdb_have_mutexes(tdb)) {
691 ret = tdb_mutex_allrecord_lock(tdb, ltype, flags);
693 ret = tdb_chainlock_gradual(tdb, ltype, flags, FREELIST_TOP,
701 /* Grab individual record locks. */
702 if (tdb_brlock(tdb, ltype, lock_offset(tdb->hash_size), 0,
704 if (tdb_have_mutexes(tdb)) {
705 tdb_mutex_allrecord_unlock(tdb);
707 tdb_brunlock(tdb, ltype, FREELIST_TOP,
713 tdb->allrecord_lock.count = 1;
714 /* If it's upgradable, it's actually exclusive so we can treat
715 * it as a write lock. */
716 tdb->allrecord_lock.ltype = upgradable ? F_WRLCK : ltype;
717 tdb->allrecord_lock.off = upgradable;
719 if (tdb_needs_recovery(tdb)) {
720 bool mark = flags & TDB_LOCK_MARK_ONLY;
721 tdb_allrecord_unlock(tdb, ltype, mark);
723 tdb->ecode = TDB_ERR_LOCK;
724 TDB_LOG((tdb, TDB_DEBUG_ERROR,
725 "tdb_lockall_mark cannot do recovery\n"));
728 if (tdb_lock_and_recover(tdb) == -1) {
731 return tdb_allrecord_lock(tdb, ltype, flags, upgradable);
739 /* unlock entire db */
740 int tdb_allrecord_unlock(struct tdb_context *tdb, int ltype, bool mark_lock)
742 /* There are no locks on read-only dbs */
743 if (tdb->read_only || tdb->traverse_read) {
744 tdb->ecode = TDB_ERR_LOCK;
748 if (tdb->allrecord_lock.count == 0) {
749 tdb->ecode = TDB_ERR_LOCK;
753 /* Upgradable locks are marked as write locks. */
754 if (tdb->allrecord_lock.ltype != (uint32_t)ltype
755 && (!tdb->allrecord_lock.off || ltype != F_RDLCK)) {
756 tdb->ecode = TDB_ERR_LOCK;
760 if (tdb->allrecord_lock.count > 1) {
761 tdb->allrecord_lock.count--;
768 if (tdb_have_mutexes(tdb)) {
769 ret = tdb_mutex_allrecord_unlock(tdb);
771 ret = tdb_brunlock(tdb, ltype,
772 lock_offset(tdb->hash_size),
776 ret = tdb_brunlock(tdb, ltype, FREELIST_TOP, 0);
780 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_unlockall failed "
781 "(%s)\n", strerror(errno)));
786 tdb->allrecord_lock.count = 0;
787 tdb->allrecord_lock.ltype = 0;
792 /* lock entire database with write lock */
793 _PUBLIC_ int tdb_lockall(struct tdb_context *tdb)
795 tdb_trace(tdb, "tdb_lockall");
796 return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false);
799 /* lock entire database with write lock - mark only */
800 _PUBLIC_ int tdb_lockall_mark(struct tdb_context *tdb)
802 tdb_trace(tdb, "tdb_lockall_mark");
803 return tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY, false);
806 /* unlock entire database with write lock - unmark only */
807 _PUBLIC_ int tdb_lockall_unmark(struct tdb_context *tdb)
809 tdb_trace(tdb, "tdb_lockall_unmark");
810 return tdb_allrecord_unlock(tdb, F_WRLCK, true);
813 /* lock entire database with write lock - nonblocking varient */
814 _PUBLIC_ int tdb_lockall_nonblock(struct tdb_context *tdb)
816 int ret = tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_NOWAIT, false);
817 tdb_trace_ret(tdb, "tdb_lockall_nonblock", ret);
821 /* unlock entire database with write lock */
822 _PUBLIC_ int tdb_unlockall(struct tdb_context *tdb)
824 tdb_trace(tdb, "tdb_unlockall");
825 return tdb_allrecord_unlock(tdb, F_WRLCK, false);
828 /* lock entire database with read lock */
829 _PUBLIC_ int tdb_lockall_read(struct tdb_context *tdb)
831 tdb_trace(tdb, "tdb_lockall_read");
832 return tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, false);
835 /* lock entire database with read lock - nonblock varient */
836 _PUBLIC_ int tdb_lockall_read_nonblock(struct tdb_context *tdb)
838 int ret = tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_NOWAIT, false);
839 tdb_trace_ret(tdb, "tdb_lockall_read_nonblock", ret);
843 /* unlock entire database with read lock */
844 _PUBLIC_ int tdb_unlockall_read(struct tdb_context *tdb)
846 tdb_trace(tdb, "tdb_unlockall_read");
847 return tdb_allrecord_unlock(tdb, F_RDLCK, false);
850 /* lock/unlock one hash chain. This is meant to be used to reduce
851 contention - it cannot guarantee how many records will be locked */
852 _PUBLIC_ int tdb_chainlock(struct tdb_context *tdb, TDB_DATA key)
854 int ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
855 tdb_trace_1rec(tdb, "tdb_chainlock", key);
859 /* lock/unlock one hash chain, non-blocking. This is meant to be used
860 to reduce contention - it cannot guarantee how many records will be
862 _PUBLIC_ int tdb_chainlock_nonblock(struct tdb_context *tdb, TDB_DATA key)
864 int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
865 tdb_trace_1rec_ret(tdb, "tdb_chainlock_nonblock", key, ret);
869 /* mark a chain as locked without actually locking it. Warning! use with great caution! */
870 _PUBLIC_ int tdb_chainlock_mark(struct tdb_context *tdb, TDB_DATA key)
872 int ret = tdb_nest_lock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
873 F_WRLCK, TDB_LOCK_MARK_ONLY);
874 tdb_trace_1rec(tdb, "tdb_chainlock_mark", key);
878 /* unmark a chain as locked without actually locking it. Warning! use with great caution! */
879 _PUBLIC_ int tdb_chainlock_unmark(struct tdb_context *tdb, TDB_DATA key)
881 tdb_trace_1rec(tdb, "tdb_chainlock_unmark", key);
882 return tdb_nest_unlock(tdb, lock_offset(BUCKET(tdb->hash_fn(&key))),
886 _PUBLIC_ int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key)
888 tdb_trace_1rec(tdb, "tdb_chainunlock", key);
889 return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
892 _PUBLIC_ int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key)
895 ret = tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
896 tdb_trace_1rec(tdb, "tdb_chainlock_read", key);
900 _PUBLIC_ int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key)
902 tdb_trace_1rec(tdb, "tdb_chainunlock_read", key);
903 return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
906 _PUBLIC_ int tdb_chainlock_read_nonblock(struct tdb_context *tdb, TDB_DATA key)
908 int ret = tdb_lock_nonblock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
909 tdb_trace_1rec_ret(tdb, "tdb_chainlock_read_nonblock", key, ret);
913 /* record lock stops delete underneath */
914 int tdb_lock_record(struct tdb_context *tdb, tdb_off_t off)
916 if (tdb->allrecord_lock.count) {
919 return off ? tdb_brlock(tdb, F_RDLCK, off, 1, TDB_LOCK_WAIT) : 0;
923 Write locks override our own fcntl readlocks, so check it here.
924 Note this is meant to be F_SETLK, *not* F_SETLKW, as it's not
925 an error to fail to get the lock here.
927 int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off)
929 struct tdb_traverse_lock *i;
930 for (i = &tdb->travlocks; i; i = i->next)
933 if (tdb->allrecord_lock.count) {
934 if (tdb->allrecord_lock.ltype == F_WRLCK) {
939 return tdb_brlock(tdb, F_WRLCK, off, 1, TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
942 int tdb_write_unlock_record(struct tdb_context *tdb, tdb_off_t off)
944 if (tdb->allrecord_lock.count) {
947 return tdb_brunlock(tdb, F_WRLCK, off, 1);
950 /* fcntl locks don't stack: avoid unlocking someone else's */
951 int tdb_unlock_record(struct tdb_context *tdb, tdb_off_t off)
953 struct tdb_traverse_lock *i;
956 if (tdb->allrecord_lock.count) {
962 for (i = &tdb->travlocks; i; i = i->next)
965 return (count == 1 ? tdb_brunlock(tdb, F_RDLCK, off, 1) : 0);
968 bool tdb_have_extra_locks(struct tdb_context *tdb)
970 unsigned int extra = tdb->num_lockrecs;
972 /* A transaction holds the lock for all records. */
973 if (!tdb->transaction && tdb->allrecord_lock.count) {
977 /* We always hold the active lock if CLEAR_IF_FIRST. */
978 if (find_nestlock(tdb, ACTIVE_LOCK)) {
982 /* In a transaction, we expect to hold the transaction lock */
983 if (tdb->transaction && find_nestlock(tdb, TRANSACTION_LOCK)) {
990 /* The transaction code uses this to remove all locks. */
991 void tdb_release_transaction_locks(struct tdb_context *tdb)
994 unsigned int active = 0;
996 if (tdb->allrecord_lock.count != 0) {
997 tdb_allrecord_unlock(tdb, tdb->allrecord_lock.ltype, false);
998 tdb->allrecord_lock.count = 0;
1001 for (i=0;i<tdb->num_lockrecs;i++) {
1002 struct tdb_lock_type *lck = &tdb->lockrecs[i];
1004 /* Don't release the active lock! Copy it to first entry. */
1005 if (lck->off == ACTIVE_LOCK) {
1006 tdb->lockrecs[active++] = *lck;
1008 tdb_brunlock(tdb, lck->ltype, lck->off, 1);
1011 tdb->num_lockrecs = active;
1014 /* Following functions are added specifically to support CTDB. */
1016 /* Don't do actual fcntl locking, just mark tdb locked */
1017 int tdb_transaction_write_lock_mark(struct tdb_context *tdb);
1018 _PUBLIC_ int tdb_transaction_write_lock_mark(struct tdb_context *tdb)
1020 return tdb_transaction_lock(tdb, F_WRLCK, TDB_LOCK_MARK_ONLY);
1023 /* Don't do actual fcntl unlocking, just mark tdb unlocked */
1024 int tdb_transaction_write_lock_unmark(struct tdb_context *tdb);
1025 _PUBLIC_ int tdb_transaction_write_lock_unmark(struct tdb_context *tdb)
1027 return tdb_nest_unlock(tdb, TRANSACTION_LOCK, F_WRLCK, true);