2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 2005
8 ** NOTE! The following LGPL license applies to the tdb
9 ** library. This does NOT imply that all of Samba is released
12 This library is free software; you can redistribute it and/or
13 modify it under the terms of the GNU Lesser General Public
14 License as published by the Free Software Foundation; either
15 version 3 of the License, or (at your option) any later version.
17 This library is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 Lesser General Public License for more details.
22 You should have received a copy of the GNU Lesser General Public
23 License along with this library; if not, see <http://www.gnu.org/licenses/>.
26 #include "tdb_private.h"
31 - only allow a single transaction at a time per database. This makes
32 using the transaction API simpler, as otherwise the caller would
33 have to cope with temporary failures in transactions that conflict
34 with other current transactions
36 - keep the transaction recovery information in the same file as the
37 database, using a special 'transaction recovery' record pointed at
38 by the header. This removes the need for extra journal files as
39 used by some other databases
41 - dynamically allocated the transaction recover record, re-using it
42 for subsequent transactions. If a larger record is needed then
43 tdb_free() the old record to place it on the normal tdb freelist
44 before allocating the new record
46 - during transactions, keep a linked list of writes all that have
47 been performed by intercepting all tdb_write() calls. The hooked
48 transaction versions of tdb_read() and tdb_write() check this
49 linked list and try to use the elements of the list in preference
52 - don't allow any locks to be held when a transaction starts,
53 otherwise we can end up with deadlock (plus lack of lock nesting
54 in posix locks would mean the lock is lost)
56 - if the caller gains a lock during the transaction but doesn't
57 release it then fail the commit
59 - allow for nested calls to tdb_transaction_start(), re-using the
60 existing transaction record. If the inner transaction is cancelled
61 then a subsequent commit will fail
63 - keep a mirrored copy of the tdb hash chain heads to allow for the
64 fast hash heads scan on traverse, updating the mirrored copy in
65 the transaction version of tdb_write
67 - allow callers to mix transaction and non-transaction use of tdb,
68 although once a transaction is started then an exclusive lock is
69 gained until the transaction is committed or cancelled
71 - the commit stategy involves first saving away all modified data
72 into a linearised buffer in the transaction recovery area, then
73 marking the transaction recovery area with a magic value to
74 indicate a valid recovery record. In total 4 fsync/msync calls are
75 needed per commit to prevent race conditions. It might be possible
76 to reduce this to 3 or even 2 with some more work.
78 - check for a valid recovery record on open of the tdb, while the
79 global lock is held. Automatically recover from the transaction
80 recovery area if needed, then continue with the open as
81 usual. This allows for smooth crash recovery with no administrator
84 - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
85 still available, but no transaction recovery area is used and no
86 fsync/msync calls are made.
88 - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
89 tdb_add_flags() transaction nesting is enabled.
90 It resets the TDB_DISALLOW_NESTING flag, as both cannot be used together.
91 The default is that transaction nesting is allowed.
92 Note: this default may change in future versions of tdb.
94 Beware. when transactions are nested a transaction successfully
95 completed with tdb_transaction_commit() can be silently unrolled later.
97 - if TDB_DISALLOW_NESTING is passed to flags in tdb open, or added using
98 tdb_add_flags() transaction nesting is disabled.
99 It resets the TDB_ALLOW_NESTING flag, as both cannot be used together.
100 An attempt create a nested transaction will fail with TDB_ERR_NESTING.
101 The default is that transaction nesting is allowed.
102 Note: this default may change in future versions of tdb.
107 hold the context of any current transaction
109 struct tdb_transaction {
110 /* we keep a mirrored copy of the tdb hash heads here so
111 tdb_next_hash_chain() can operate efficiently */
112 uint32_t *hash_heads;
114 /* the original io methods - used to do IOs to the real db */
115 const struct tdb_methods *io_methods;
117 /* the list of transaction blocks. When a block is first
118 written to, it gets created in this list */
121 uint32_t block_size; /* bytes in each block */
122 uint32_t last_block_size; /* number of valid bytes in the last block */
124 /* non-zero when an internal transaction error has
125 occurred. All write operations will then fail until the
126 transaction is ended */
127 int transaction_error;
129 /* when inside a transaction we need to keep track of any
130 nested tdb_transaction_start() calls, as these are allowed,
131 but don't create a new transaction */
134 /* set when a prepare has already occurred */
136 tdb_off_t magic_offset;
138 /* old file size before transaction */
139 tdb_len_t old_map_size;
141 /* we should re-pack on commit */
147 read while in a transaction. We need to check first if the data is in our list
148 of transaction elements, then if not do a real read
150 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
151 tdb_len_t len, int cv)
155 /* break it down into block sized ops */
156 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
157 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
158 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
163 buf = (void *)(len2 + (char *)buf);
170 blk = off / tdb->transaction->block_size;
172 /* see if we have it in the block list */
173 if (tdb->transaction->num_blocks <= blk ||
174 tdb->transaction->blocks[blk] == NULL) {
175 /* nope, do a real read */
176 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
182 /* it is in the block list. Now check for the last block */
183 if (blk == tdb->transaction->num_blocks-1) {
184 if (len > tdb->transaction->last_block_size) {
189 /* now copy it out of this block */
190 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
192 tdb_convert(buf, len);
197 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
198 tdb->ecode = TDB_ERR_IO;
199 tdb->transaction->transaction_error = 1;
205 write while in a transaction
207 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
208 const void *buf, tdb_len_t len)
212 /* Only a commit is allowed on a prepared transaction */
213 if (tdb->transaction->prepared) {
214 tdb->ecode = TDB_ERR_EINVAL;
215 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
216 tdb->transaction->transaction_error = 1;
220 /* if the write is to a hash head, then update the transaction
222 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
223 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
224 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
225 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
228 /* break it up into block sized chunks */
229 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
230 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
231 if (transaction_write(tdb, off, buf, len2) != 0) {
237 buf = (const void *)(len2 + (const char *)buf);
245 blk = off / tdb->transaction->block_size;
246 off = off % tdb->transaction->block_size;
248 if (tdb->transaction->num_blocks <= blk) {
249 uint8_t **new_blocks;
250 /* expand the blocks array */
251 if (tdb->transaction->blocks == NULL) {
252 new_blocks = (uint8_t **)malloc(
253 (blk+1)*sizeof(uint8_t *));
255 new_blocks = (uint8_t **)realloc(
256 tdb->transaction->blocks,
257 (blk+1)*sizeof(uint8_t *));
259 if (new_blocks == NULL) {
260 tdb->ecode = TDB_ERR_OOM;
263 memset(&new_blocks[tdb->transaction->num_blocks], 0,
264 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
265 tdb->transaction->blocks = new_blocks;
266 tdb->transaction->num_blocks = blk+1;
267 tdb->transaction->last_block_size = 0;
270 /* allocate and fill a block? */
271 if (tdb->transaction->blocks[blk] == NULL) {
272 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
273 if (tdb->transaction->blocks[blk] == NULL) {
274 tdb->ecode = TDB_ERR_OOM;
275 tdb->transaction->transaction_error = 1;
278 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
279 tdb_len_t len2 = tdb->transaction->block_size;
280 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
281 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
283 if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
284 tdb->transaction->blocks[blk],
286 SAFE_FREE(tdb->transaction->blocks[blk]);
287 tdb->ecode = TDB_ERR_IO;
290 if (blk == tdb->transaction->num_blocks-1) {
291 tdb->transaction->last_block_size = len2;
296 /* overwrite part of an existing block */
298 memset(tdb->transaction->blocks[blk] + off, 0, len);
300 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
302 if (blk == tdb->transaction->num_blocks-1) {
303 if (len + off > tdb->transaction->last_block_size) {
304 tdb->transaction->last_block_size = len + off;
311 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
312 (blk*tdb->transaction->block_size) + off, len));
313 tdb->transaction->transaction_error = 1;
319 write while in a transaction - this varient never expands the transaction blocks, it only
320 updates existing blocks. This means it cannot change the recovery size
322 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
323 const void *buf, tdb_len_t len)
327 /* break it up into block sized chunks */
328 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
329 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
330 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
336 buf = (const void *)(len2 + (const char *)buf);
344 blk = off / tdb->transaction->block_size;
345 off = off % tdb->transaction->block_size;
347 if (tdb->transaction->num_blocks <= blk ||
348 tdb->transaction->blocks[blk] == NULL) {
352 if (blk == tdb->transaction->num_blocks-1 &&
353 off + len > tdb->transaction->last_block_size) {
354 if (off >= tdb->transaction->last_block_size) {
357 len = tdb->transaction->last_block_size - off;
360 /* overwrite part of an existing block */
361 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
368 accelerated hash chain head search, using the cached hash heads
370 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
373 for (;h < tdb->header.hash_size;h++) {
374 /* the +1 takes account of the freelist */
375 if (0 != tdb->transaction->hash_heads[h+1]) {
383 out of bounds check during a transaction
385 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
387 if (len <= tdb->map_size) {
390 tdb->ecode = TDB_ERR_IO;
395 transaction version of tdb_expand().
397 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
400 /* add a write to the transaction elements, so subsequent
401 reads see the zero data */
402 if (transaction_write(tdb, size, NULL, addition) != 0) {
406 tdb->transaction->need_repack = true;
412 brlock during a transaction - ignore them
414 static int transaction_brlock(struct tdb_context *tdb,
415 int rw_type, tdb_off_t offset, size_t len,
416 enum tdb_lock_flags flags)
421 static int transaction_brunlock(struct tdb_context *tdb,
422 int rw_type, tdb_off_t offset, size_t len)
427 static const struct tdb_methods transaction_methods = {
430 transaction_next_hash_chain,
432 transaction_expand_file,
440 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
442 if (tdb->flags & TDB_NOSYNC) {
446 if (fsync(tdb->fd) != 0) {
447 tdb->ecode = TDB_ERR_IO;
448 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
453 tdb_off_t moffset = offset & ~(tdb->page_size-1);
454 if (msync(moffset + (char *)tdb->map_ptr,
455 length + (offset - moffset), MS_SYNC) != 0) {
456 tdb->ecode = TDB_ERR_IO;
457 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
466 /* ltype is F_WRLCK after prepare. */
467 int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
471 if (tdb->transaction == NULL) {
472 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
476 if (tdb->transaction->nesting != 0) {
477 tdb->transaction->transaction_error = 1;
478 tdb->transaction->nesting--;
482 tdb->map_size = tdb->transaction->old_map_size;
484 /* free all the transaction blocks */
485 for (i=0;i<tdb->transaction->num_blocks;i++) {
486 if (tdb->transaction->blocks[i] != NULL) {
487 free(tdb->transaction->blocks[i]);
490 SAFE_FREE(tdb->transaction->blocks);
492 if (tdb->transaction->magic_offset) {
493 const struct tdb_methods *methods = tdb->transaction->io_methods;
496 /* remove the recovery marker */
497 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 4) == -1 ||
498 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
499 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
504 /* remove any global lock created during the transaction */
505 if (tdb->global_lock.count != 0) {
506 tdb_brunlock(tdb, tdb->global_lock.ltype,
507 FREELIST_TOP, 4*tdb->header.hash_size);
508 tdb->global_lock.count = 0;
511 /* remove any locks created during the transaction */
512 if (tdb->num_locks != 0) {
513 for (i=0;i<tdb->num_lockrecs;i++) {
514 tdb_brunlock(tdb, tdb->lockrecs[i].ltype,
515 FREELIST_TOP+4*tdb->lockrecs[i].list, 1);
518 tdb->num_lockrecs = 0;
519 SAFE_FREE(tdb->lockrecs);
522 /* restore the normal io methods */
523 tdb->methods = tdb->transaction->io_methods;
525 tdb_brunlock(tdb, ltype, FREELIST_TOP, 0);
526 tdb_transaction_unlock(tdb, F_WRLCK);
527 SAFE_FREE(tdb->transaction->hash_heads);
528 SAFE_FREE(tdb->transaction);
534 start a tdb transaction. No token is returned, as only a single
535 transaction is allowed to be pending per tdb_context
537 int tdb_transaction_start(struct tdb_context *tdb)
539 /* some sanity checks */
540 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
541 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
542 tdb->ecode = TDB_ERR_EINVAL;
546 /* cope with nested tdb_transaction_start() calls */
547 if (tdb->transaction != NULL) {
548 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
549 tdb->ecode = TDB_ERR_NESTING;
552 tdb_trace(tdb, "tdb_transaction_start");
553 tdb->transaction->nesting++;
554 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
555 tdb->transaction->nesting));
559 if (tdb->num_locks != 0 || tdb->global_lock.count) {
560 /* the caller must not have any locks when starting a
561 transaction as otherwise we'll be screwed by lack
562 of nested locks in posix */
563 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
564 tdb->ecode = TDB_ERR_LOCK;
568 if (tdb->travlocks.next != NULL) {
569 /* you cannot use transactions inside a traverse (although you can use
570 traverse inside a transaction) as otherwise you can end up with
572 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
573 tdb->ecode = TDB_ERR_LOCK;
577 tdb->transaction = (struct tdb_transaction *)
578 calloc(sizeof(struct tdb_transaction), 1);
579 if (tdb->transaction == NULL) {
580 tdb->ecode = TDB_ERR_OOM;
584 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
585 tdb->transaction->block_size = tdb->page_size;
587 /* get the transaction write lock. This is a blocking lock. As
588 discussed with Volker, there are a number of ways we could
589 make this async, which we will probably do in the future */
590 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
591 SAFE_FREE(tdb->transaction->blocks);
592 SAFE_FREE(tdb->transaction);
596 /* get a read lock from the freelist to the end of file. This
597 is upgraded to a write lock during the commit */
598 if (tdb_brlock(tdb, F_RDLCK, FREELIST_TOP, 0, TDB_LOCK_WAIT) == -1) {
599 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
600 tdb->ecode = TDB_ERR_LOCK;
604 /* setup a copy of the hash table heads so the hash scan in
605 traverse can be fast */
606 tdb->transaction->hash_heads = (uint32_t *)
607 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
608 if (tdb->transaction->hash_heads == NULL) {
609 tdb->ecode = TDB_ERR_OOM;
612 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
613 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
614 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
615 tdb->ecode = TDB_ERR_IO;
619 /* make sure we know about any file expansions already done by
621 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
622 tdb->transaction->old_map_size = tdb->map_size;
624 /* finally hook the io methods, replacing them with
625 transaction specific methods */
626 tdb->transaction->io_methods = tdb->methods;
627 tdb->methods = &transaction_methods;
629 /* Trace at the end, so we get sequence number correct. */
630 tdb_trace(tdb, "tdb_transaction_start");
634 tdb_brunlock(tdb, F_RDLCK, FREELIST_TOP, 0);
635 tdb_transaction_unlock(tdb, F_WRLCK);
636 SAFE_FREE(tdb->transaction->blocks);
637 SAFE_FREE(tdb->transaction->hash_heads);
638 SAFE_FREE(tdb->transaction);
644 cancel the current transaction
646 int tdb_transaction_cancel(struct tdb_context *tdb)
649 tdb_trace(tdb, "tdb_transaction_cancel");
650 if (tdb->transaction && tdb->transaction->prepared)
652 return _tdb_transaction_cancel(tdb, ltype);
656 work out how much space the linearised recovery data will consume
658 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
660 tdb_len_t recovery_size = 0;
663 recovery_size = sizeof(uint32_t);
664 for (i=0;i<tdb->transaction->num_blocks;i++) {
665 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
668 if (tdb->transaction->blocks[i] == NULL) {
671 recovery_size += 2*sizeof(tdb_off_t);
672 if (i == tdb->transaction->num_blocks-1) {
673 recovery_size += tdb->transaction->last_block_size;
675 recovery_size += tdb->transaction->block_size;
679 return recovery_size;
683 allocate the recovery area, or use an existing recovery area if it is
686 static int tdb_recovery_allocate(struct tdb_context *tdb,
687 tdb_len_t *recovery_size,
688 tdb_off_t *recovery_offset,
689 tdb_len_t *recovery_max_size)
691 struct tdb_record rec;
692 const struct tdb_methods *methods = tdb->transaction->io_methods;
693 tdb_off_t recovery_head;
695 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
696 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
702 if (recovery_head != 0 &&
703 methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
704 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
708 *recovery_size = tdb_recovery_size(tdb);
710 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
711 /* it fits in the existing area */
712 *recovery_max_size = rec.rec_len;
713 *recovery_offset = recovery_head;
717 /* we need to free up the old recovery area, then allocate a
718 new one at the end of the file. Note that we cannot use
719 tdb_allocate() to allocate the new one as that might return
720 us an area that is being currently used (as of the start of
722 if (recovery_head != 0) {
723 if (tdb_free(tdb, recovery_head, &rec) == -1) {
724 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
729 /* the tdb_free() call might have increased the recovery size */
730 *recovery_size = tdb_recovery_size(tdb);
732 /* round up to a multiple of page size */
733 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
734 *recovery_offset = tdb->map_size;
735 recovery_head = *recovery_offset;
737 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
738 (tdb->map_size - tdb->transaction->old_map_size) +
739 sizeof(rec) + *recovery_max_size) == -1) {
740 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
744 /* remap the file (if using mmap) */
745 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
747 /* we have to reset the old map size so that we don't try to expand the file
748 again in the transaction commit, which would destroy the recovery area */
749 tdb->transaction->old_map_size = tdb->map_size;
751 /* write the recovery header offset and sync - we can sync without a race here
752 as the magic ptr in the recovery record has not been set */
753 CONVERT(recovery_head);
754 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
755 &recovery_head, sizeof(tdb_off_t)) == -1) {
756 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
759 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
760 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
769 setup the recovery data that will be used on a crash during commit
771 static int transaction_setup_recovery(struct tdb_context *tdb,
772 tdb_off_t *magic_offset)
774 tdb_len_t recovery_size;
775 unsigned char *data, *p;
776 const struct tdb_methods *methods = tdb->transaction->io_methods;
777 struct tdb_record *rec;
778 tdb_off_t recovery_offset, recovery_max_size;
779 tdb_off_t old_map_size = tdb->transaction->old_map_size;
780 uint32_t magic, tailer;
784 check that the recovery area has enough space
786 if (tdb_recovery_allocate(tdb, &recovery_size,
787 &recovery_offset, &recovery_max_size) == -1) {
791 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
793 tdb->ecode = TDB_ERR_OOM;
797 rec = (struct tdb_record *)data;
798 memset(rec, 0, sizeof(*rec));
801 rec->data_len = recovery_size;
802 rec->rec_len = recovery_max_size;
803 rec->key_len = old_map_size;
806 /* build the recovery data into a single blob to allow us to do a single
807 large write, which should be more efficient */
808 p = data + sizeof(*rec);
809 for (i=0;i<tdb->transaction->num_blocks;i++) {
813 if (tdb->transaction->blocks[i] == NULL) {
817 offset = i * tdb->transaction->block_size;
818 length = tdb->transaction->block_size;
819 if (i == tdb->transaction->num_blocks-1) {
820 length = tdb->transaction->last_block_size;
823 if (offset >= old_map_size) {
826 if (offset + length > tdb->transaction->old_map_size) {
827 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
829 tdb->ecode = TDB_ERR_CORRUPT;
832 memcpy(p, &offset, 4);
833 memcpy(p+4, &length, 4);
837 /* the recovery area contains the old data, not the
838 new data, so we have to call the original tdb_read
840 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
842 tdb->ecode = TDB_ERR_IO;
849 tailer = sizeof(*rec) + recovery_max_size;
850 memcpy(p, &tailer, 4);
853 /* write the recovery data to the recovery area */
854 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
855 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
857 tdb->ecode = TDB_ERR_IO;
860 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
861 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
863 tdb->ecode = TDB_ERR_IO;
867 /* as we don't have ordered writes, we have to sync the recovery
868 data before we update the magic to indicate that the recovery
870 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
877 magic = TDB_RECOVERY_MAGIC;
880 *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
882 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
883 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
884 tdb->ecode = TDB_ERR_IO;
887 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
888 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
889 tdb->ecode = TDB_ERR_IO;
893 /* ensure the recovery magic marker is on disk */
894 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
901 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
903 const struct tdb_methods *methods;
905 if (tdb->transaction == NULL) {
906 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
910 if (tdb->transaction->prepared) {
911 tdb->ecode = TDB_ERR_EINVAL;
912 _tdb_transaction_cancel(tdb, F_WRLCK);
913 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
917 if (tdb->transaction->transaction_error) {
918 tdb->ecode = TDB_ERR_IO;
919 _tdb_transaction_cancel(tdb, F_RDLCK);
920 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
925 if (tdb->transaction->nesting != 0) {
926 tdb->transaction->nesting--;
930 /* check for a null transaction */
931 if (tdb->transaction->blocks == NULL) {
935 methods = tdb->transaction->io_methods;
937 /* if there are any locks pending then the caller has not
938 nested their locks properly, so fail the transaction */
939 if (tdb->num_locks || tdb->global_lock.count) {
940 tdb->ecode = TDB_ERR_LOCK;
941 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
942 _tdb_transaction_cancel(tdb, F_RDLCK);
946 /* upgrade the main transaction lock region to a write lock */
947 if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
948 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
949 tdb->ecode = TDB_ERR_LOCK;
950 _tdb_transaction_cancel(tdb, F_RDLCK);
954 /* get the global lock - this prevents new users attaching to the database
956 if (tdb_brlock(tdb, F_WRLCK, GLOBAL_LOCK, 1, TDB_LOCK_WAIT) == -1) {
957 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
958 tdb->ecode = TDB_ERR_LOCK;
959 _tdb_transaction_cancel(tdb, F_WRLCK);
963 if (!(tdb->flags & TDB_NOSYNC)) {
964 /* write the recovery data to the end of the file */
965 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
966 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
967 tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1);
968 _tdb_transaction_cancel(tdb, F_WRLCK);
973 tdb->transaction->prepared = true;
975 /* expand the file to the new size if needed */
976 if (tdb->map_size != tdb->transaction->old_map_size) {
977 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
979 tdb->transaction->old_map_size) == -1) {
980 tdb->ecode = TDB_ERR_IO;
981 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
982 tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1);
983 _tdb_transaction_cancel(tdb, F_WRLCK);
986 tdb->map_size = tdb->transaction->old_map_size;
987 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
990 /* Keep the global lock until the actual commit */
996 prepare to commit the current transaction
998 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
1000 tdb_trace(tdb, "tdb_transaction_prepare_commit");
1001 return _tdb_transaction_prepare_commit(tdb);
1005 commit the current transaction
1007 int tdb_transaction_commit(struct tdb_context *tdb)
1009 const struct tdb_methods *methods;
1013 if (tdb->transaction == NULL) {
1014 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
1018 tdb_trace(tdb, "tdb_transaction_commit");
1020 if (tdb->transaction->transaction_error) {
1021 tdb->ecode = TDB_ERR_IO;
1022 tdb_transaction_cancel(tdb);
1023 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1028 if (tdb->transaction->nesting != 0) {
1029 tdb->transaction->nesting--;
1033 /* check for a null transaction */
1034 if (tdb->transaction->blocks == NULL) {
1035 _tdb_transaction_cancel(tdb, F_RDLCK);
1039 if (!tdb->transaction->prepared) {
1040 int ret = _tdb_transaction_prepare_commit(tdb);
1045 methods = tdb->transaction->io_methods;
1047 /* perform all the writes */
1048 for (i=0;i<tdb->transaction->num_blocks;i++) {
1052 if (tdb->transaction->blocks[i] == NULL) {
1056 offset = i * tdb->transaction->block_size;
1057 length = tdb->transaction->block_size;
1058 if (i == tdb->transaction->num_blocks-1) {
1059 length = tdb->transaction->last_block_size;
1062 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1063 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1065 /* we've overwritten part of the data and
1066 possibly expanded the file, so we need to
1067 run the crash recovery code */
1068 tdb->methods = methods;
1069 tdb_transaction_recover(tdb);
1071 _tdb_transaction_cancel(tdb, F_WRLCK);
1072 tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1);
1074 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1077 SAFE_FREE(tdb->transaction->blocks[i]);
1080 SAFE_FREE(tdb->transaction->blocks);
1081 tdb->transaction->num_blocks = 0;
1083 /* ensure the new data is on disk */
1084 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1088 tdb_brunlock(tdb, F_WRLCK, GLOBAL_LOCK, 1);
1091 TODO: maybe write to some dummy hdr field, or write to magic
1092 offset without mmap, before the last sync, instead of the
1096 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1097 don't change the mtime of the file, this means the file may
1098 not be backed up (as tdb rounding to block sizes means that
1099 file size changes are quite rare too). The following forces
1100 mtime changes when a transaction completes */
1102 utime(tdb->name, NULL);
1105 need_repack = tdb->transaction->need_repack;
1107 /* use a transaction cancel to free memory and remove the
1108 transaction locks */
1109 _tdb_transaction_cancel(tdb, F_WRLCK);
1112 return tdb_repack(tdb);
1120 recover from an aborted transaction. Must be called with exclusive
1121 database write access already established (including the global
1122 lock to prevent new processes attaching)
1124 int tdb_transaction_recover(struct tdb_context *tdb)
1126 tdb_off_t recovery_head, recovery_eof;
1127 unsigned char *data, *p;
1129 struct tdb_record rec;
1131 /* find the recovery area */
1132 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1133 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1134 tdb->ecode = TDB_ERR_IO;
1138 if (recovery_head == 0) {
1139 /* we have never allocated a recovery record */
1143 /* read the recovery record */
1144 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1145 sizeof(rec), DOCONV()) == -1) {
1146 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1147 tdb->ecode = TDB_ERR_IO;
1151 if (rec.magic != TDB_RECOVERY_MAGIC) {
1152 /* there is no valid recovery data */
1156 if (tdb->read_only) {
1157 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1158 tdb->ecode = TDB_ERR_CORRUPT;
1162 recovery_eof = rec.key_len;
1164 data = (unsigned char *)malloc(rec.data_len);
1166 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1167 tdb->ecode = TDB_ERR_OOM;
1171 /* read the full recovery data */
1172 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1173 rec.data_len, 0) == -1) {
1174 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1175 tdb->ecode = TDB_ERR_IO;
1179 /* recover the file data */
1181 while (p+8 < data + rec.data_len) {
1187 memcpy(&len, p+4, 4);
1189 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1191 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1192 tdb->ecode = TDB_ERR_IO;
1200 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1201 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1202 tdb->ecode = TDB_ERR_IO;
1206 /* if the recovery area is after the recovered eof then remove it */
1207 if (recovery_eof <= recovery_head) {
1208 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1209 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1210 tdb->ecode = TDB_ERR_IO;
1215 /* remove the recovery magic */
1216 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
1218 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1219 tdb->ecode = TDB_ERR_IO;
1223 /* reduce the file size to the old size */
1225 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1226 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1227 tdb->ecode = TDB_ERR_IO;
1230 tdb->map_size = recovery_eof;
1233 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1234 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1235 tdb->ecode = TDB_ERR_IO;
1239 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",