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_NO_NESTING is passed to flags in tdb open then transaction
89 nesting is disabled. tdb_transaction_start() will then implicitely
90 cancel any pending transactions and always start a new transaction
91 context instead of nesting.
97 hold the context of any current transaction
99 struct tdb_transaction {
100 /* we keep a mirrored copy of the tdb hash heads here so
101 tdb_next_hash_chain() can operate efficiently */
102 uint32_t *hash_heads;
104 /* the original io methods - used to do IOs to the real db */
105 const struct tdb_methods *io_methods;
107 /* the list of transaction blocks. When a block is first
108 written to, it gets created in this list */
111 uint32_t block_size; /* bytes in each block */
112 uint32_t last_block_size; /* number of valid bytes in the last block */
114 /* non-zero when an internal transaction error has
115 occurred. All write operations will then fail until the
116 transaction is ended */
117 int transaction_error;
119 /* when inside a transaction we need to keep track of any
120 nested tdb_transaction_start() calls, as these are allowed,
121 but don't create a new transaction */
124 /* set when a prepare has already occurred */
126 tdb_off_t magic_offset;
128 /* old file size before transaction */
129 tdb_len_t old_map_size;
131 /* we should re-pack on commit */
137 read while in a transaction. We need to check first if the data is in our list
138 of transaction elements, then if not do a real read
140 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
141 tdb_len_t len, int cv)
145 /* Only a commit is allowed on a prepared transaction */
146 if (tdb->transaction->prepared) {
147 tdb->ecode = TDB_ERR_EINVAL;
148 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: transaction already prepared, read not allowed\n"));
149 tdb->transaction->transaction_error = 1;
153 /* break it down into block sized ops */
154 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
155 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
156 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
161 buf = (void *)(len2 + (char *)buf);
168 blk = off / tdb->transaction->block_size;
170 /* see if we have it in the block list */
171 if (tdb->transaction->num_blocks <= blk ||
172 tdb->transaction->blocks[blk] == NULL) {
173 /* nope, do a real read */
174 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
180 /* it is in the block list. Now check for the last block */
181 if (blk == tdb->transaction->num_blocks-1) {
182 if (len > tdb->transaction->last_block_size) {
187 /* now copy it out of this block */
188 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
190 tdb_convert(buf, len);
195 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
196 tdb->ecode = TDB_ERR_IO;
197 tdb->transaction->transaction_error = 1;
203 write while in a transaction
205 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
206 const void *buf, tdb_len_t len)
210 /* Only a commit is allowed on a prepared transaction */
211 if (tdb->transaction->prepared) {
212 tdb->ecode = TDB_ERR_EINVAL;
213 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
214 tdb->transaction->transaction_error = 1;
218 /* if the write is to a hash head, then update the transaction
220 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
221 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
222 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
223 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
226 /* break it up into block sized chunks */
227 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
228 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
229 if (transaction_write(tdb, off, buf, len2) != 0) {
235 buf = (const void *)(len2 + (const char *)buf);
243 blk = off / tdb->transaction->block_size;
244 off = off % tdb->transaction->block_size;
246 if (tdb->transaction->num_blocks <= blk) {
247 uint8_t **new_blocks;
248 /* expand the blocks array */
249 if (tdb->transaction->blocks == NULL) {
250 new_blocks = (uint8_t **)malloc(
251 (blk+1)*sizeof(uint8_t *));
253 new_blocks = (uint8_t **)realloc(
254 tdb->transaction->blocks,
255 (blk+1)*sizeof(uint8_t *));
257 if (new_blocks == NULL) {
258 tdb->ecode = TDB_ERR_OOM;
261 memset(&new_blocks[tdb->transaction->num_blocks], 0,
262 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
263 tdb->transaction->blocks = new_blocks;
264 tdb->transaction->num_blocks = blk+1;
265 tdb->transaction->last_block_size = 0;
268 /* allocate and fill a block? */
269 if (tdb->transaction->blocks[blk] == NULL) {
270 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
271 if (tdb->transaction->blocks[blk] == NULL) {
272 tdb->ecode = TDB_ERR_OOM;
273 tdb->transaction->transaction_error = 1;
276 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
277 tdb_len_t len2 = tdb->transaction->block_size;
278 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
279 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
281 if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
282 tdb->transaction->blocks[blk],
284 SAFE_FREE(tdb->transaction->blocks[blk]);
285 tdb->ecode = TDB_ERR_IO;
288 if (blk == tdb->transaction->num_blocks-1) {
289 tdb->transaction->last_block_size = len2;
294 /* overwrite part of an existing block */
296 memset(tdb->transaction->blocks[blk] + off, 0, len);
298 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
300 if (blk == tdb->transaction->num_blocks-1) {
301 if (len + off > tdb->transaction->last_block_size) {
302 tdb->transaction->last_block_size = len + off;
309 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
310 (blk*tdb->transaction->block_size) + off, len));
311 tdb->transaction->transaction_error = 1;
317 write while in a transaction - this varient never expands the transaction blocks, it only
318 updates existing blocks. This means it cannot change the recovery size
320 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
321 const void *buf, tdb_len_t len)
325 /* break it up into block sized chunks */
326 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
327 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
328 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
334 buf = (const void *)(len2 + (const char *)buf);
342 blk = off / tdb->transaction->block_size;
343 off = off % tdb->transaction->block_size;
345 if (tdb->transaction->num_blocks <= blk ||
346 tdb->transaction->blocks[blk] == NULL) {
350 if (blk == tdb->transaction->num_blocks-1 &&
351 off + len > tdb->transaction->last_block_size) {
352 if (off >= tdb->transaction->last_block_size) {
355 len = tdb->transaction->last_block_size - off;
358 /* overwrite part of an existing block */
359 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
366 accelerated hash chain head search, using the cached hash heads
368 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
371 for (;h < tdb->header.hash_size;h++) {
372 /* the +1 takes account of the freelist */
373 if (0 != tdb->transaction->hash_heads[h+1]) {
381 out of bounds check during a transaction
383 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
385 if (len <= tdb->map_size) {
388 return TDB_ERRCODE(TDB_ERR_IO, -1);
392 transaction version of tdb_expand().
394 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
397 /* add a write to the transaction elements, so subsequent
398 reads see the zero data */
399 if (transaction_write(tdb, size, NULL, addition) != 0) {
403 tdb->transaction->need_repack = true;
409 brlock during a transaction - ignore them
411 static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset,
412 int rw_type, int lck_type, int probe, size_t len)
417 static const struct tdb_methods transaction_methods = {
420 transaction_next_hash_chain,
422 transaction_expand_file,
429 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
431 if (tdb->flags & TDB_NOSYNC) {
435 if (fsync(tdb->fd) != 0) {
436 tdb->ecode = TDB_ERR_IO;
437 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
442 tdb_off_t moffset = offset & ~(tdb->page_size-1);
443 if (msync(moffset + (char *)tdb->map_ptr,
444 length + (offset - moffset), MS_SYNC) != 0) {
445 tdb->ecode = TDB_ERR_IO;
446 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
455 int tdb_transaction_cancel_internal(struct tdb_context *tdb)
459 if (tdb->transaction == NULL) {
460 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
464 if (tdb->transaction->nesting != 0) {
465 tdb->transaction->transaction_error = 1;
466 tdb->transaction->nesting--;
470 tdb->map_size = tdb->transaction->old_map_size;
472 /* free all the transaction blocks */
473 for (i=0;i<tdb->transaction->num_blocks;i++) {
474 if (tdb->transaction->blocks[i] != NULL) {
475 free(tdb->transaction->blocks[i]);
478 SAFE_FREE(tdb->transaction->blocks);
480 if (tdb->transaction->magic_offset) {
481 const struct tdb_methods *methods = tdb->transaction->io_methods;
484 /* remove the recovery marker */
485 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 4) == -1 ||
486 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
487 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
492 /* remove any global lock created during the transaction */
493 if (tdb->global_lock.count != 0) {
494 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size);
495 tdb->global_lock.count = 0;
498 /* remove any locks created during the transaction */
499 if (tdb->num_locks != 0) {
500 for (i=0;i<tdb->num_lockrecs;i++) {
501 tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
502 F_UNLCK,F_SETLKW, 0, 1);
505 tdb->num_lockrecs = 0;
506 SAFE_FREE(tdb->lockrecs);
509 /* restore the normal io methods */
510 tdb->methods = tdb->transaction->io_methods;
512 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
513 tdb_transaction_unlock(tdb);
514 SAFE_FREE(tdb->transaction->hash_heads);
515 SAFE_FREE(tdb->transaction);
521 start a tdb transaction. No token is returned, as only a single
522 transaction is allowed to be pending per tdb_context
524 int tdb_transaction_start(struct tdb_context *tdb)
526 /* some sanity checks */
527 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
528 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
529 tdb->ecode = TDB_ERR_EINVAL;
533 /* cope with nested tdb_transaction_start() calls */
534 if (tdb->transaction != NULL) {
535 tdb_trace(tdb, "tdb_transaction_start");
536 if (!tdb->flags & TDB_NO_NESTING) {
537 tdb->transaction->nesting++;
538 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
539 tdb->transaction->nesting));
542 tdb_transaction_cancel_internal(tdb);
543 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: cancelling previous transaction\n"));
547 if (tdb->num_locks != 0 || tdb->global_lock.count) {
548 /* the caller must not have any locks when starting a
549 transaction as otherwise we'll be screwed by lack
550 of nested locks in posix */
551 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
552 tdb->ecode = TDB_ERR_LOCK;
556 if (tdb->travlocks.next != NULL) {
557 /* you cannot use transactions inside a traverse (although you can use
558 traverse inside a transaction) as otherwise you can end up with
560 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
561 tdb->ecode = TDB_ERR_LOCK;
565 tdb->transaction = (struct tdb_transaction *)
566 calloc(sizeof(struct tdb_transaction), 1);
567 if (tdb->transaction == NULL) {
568 tdb->ecode = TDB_ERR_OOM;
572 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
573 tdb->transaction->block_size = tdb->page_size;
575 /* get the transaction write lock. This is a blocking lock. As
576 discussed with Volker, there are a number of ways we could
577 make this async, which we will probably do in the future */
578 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
579 SAFE_FREE(tdb->transaction->blocks);
580 SAFE_FREE(tdb->transaction);
584 /* get a read lock from the freelist to the end of file. This
585 is upgraded to a write lock during the commit */
586 if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) {
587 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
588 tdb->ecode = TDB_ERR_LOCK;
592 /* setup a copy of the hash table heads so the hash scan in
593 traverse can be fast */
594 tdb->transaction->hash_heads = (uint32_t *)
595 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
596 if (tdb->transaction->hash_heads == NULL) {
597 tdb->ecode = TDB_ERR_OOM;
600 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
601 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
602 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
603 tdb->ecode = TDB_ERR_IO;
607 /* make sure we know about any file expansions already done by
609 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
610 tdb->transaction->old_map_size = tdb->map_size;
612 /* finally hook the io methods, replacing them with
613 transaction specific methods */
614 tdb->transaction->io_methods = tdb->methods;
615 tdb->methods = &transaction_methods;
617 /* Trace at the end, so we get sequence number correct. */
618 tdb_trace(tdb, "tdb_transaction_start");
622 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
623 tdb_transaction_unlock(tdb);
624 SAFE_FREE(tdb->transaction->blocks);
625 SAFE_FREE(tdb->transaction->hash_heads);
626 SAFE_FREE(tdb->transaction);
632 cancel the current transaction
634 int tdb_transaction_cancel(struct tdb_context *tdb)
636 tdb_trace(tdb, "tdb_transaction_cancel");
637 return tdb_transaction_cancel_internal(tdb);
641 work out how much space the linearised recovery data will consume
643 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
645 tdb_len_t recovery_size = 0;
648 recovery_size = sizeof(uint32_t);
649 for (i=0;i<tdb->transaction->num_blocks;i++) {
650 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
653 if (tdb->transaction->blocks[i] == NULL) {
656 recovery_size += 2*sizeof(tdb_off_t);
657 if (i == tdb->transaction->num_blocks-1) {
658 recovery_size += tdb->transaction->last_block_size;
660 recovery_size += tdb->transaction->block_size;
664 return recovery_size;
668 allocate the recovery area, or use an existing recovery area if it is
671 static int tdb_recovery_allocate(struct tdb_context *tdb,
672 tdb_len_t *recovery_size,
673 tdb_off_t *recovery_offset,
674 tdb_len_t *recovery_max_size)
676 struct list_struct rec;
677 const struct tdb_methods *methods = tdb->transaction->io_methods;
678 tdb_off_t recovery_head;
680 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
681 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
687 if (recovery_head != 0 &&
688 methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
689 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
693 *recovery_size = tdb_recovery_size(tdb);
695 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
696 /* it fits in the existing area */
697 *recovery_max_size = rec.rec_len;
698 *recovery_offset = recovery_head;
702 /* we need to free up the old recovery area, then allocate a
703 new one at the end of the file. Note that we cannot use
704 tdb_allocate() to allocate the new one as that might return
705 us an area that is being currently used (as of the start of
707 if (recovery_head != 0) {
708 if (tdb_free(tdb, recovery_head, &rec) == -1) {
709 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
714 /* the tdb_free() call might have increased the recovery size */
715 *recovery_size = tdb_recovery_size(tdb);
717 /* round up to a multiple of page size */
718 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
719 *recovery_offset = tdb->map_size;
720 recovery_head = *recovery_offset;
722 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
723 (tdb->map_size - tdb->transaction->old_map_size) +
724 sizeof(rec) + *recovery_max_size) == -1) {
725 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
729 /* remap the file (if using mmap) */
730 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
732 /* we have to reset the old map size so that we don't try to expand the file
733 again in the transaction commit, which would destroy the recovery area */
734 tdb->transaction->old_map_size = tdb->map_size;
736 /* write the recovery header offset and sync - we can sync without a race here
737 as the magic ptr in the recovery record has not been set */
738 CONVERT(recovery_head);
739 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
740 &recovery_head, sizeof(tdb_off_t)) == -1) {
741 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
744 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
745 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
754 setup the recovery data that will be used on a crash during commit
756 static int transaction_setup_recovery(struct tdb_context *tdb,
757 tdb_off_t *magic_offset)
759 tdb_len_t recovery_size;
760 unsigned char *data, *p;
761 const struct tdb_methods *methods = tdb->transaction->io_methods;
762 struct list_struct *rec;
763 tdb_off_t recovery_offset, recovery_max_size;
764 tdb_off_t old_map_size = tdb->transaction->old_map_size;
765 uint32_t magic, tailer;
769 check that the recovery area has enough space
771 if (tdb_recovery_allocate(tdb, &recovery_size,
772 &recovery_offset, &recovery_max_size) == -1) {
776 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
778 tdb->ecode = TDB_ERR_OOM;
782 rec = (struct list_struct *)data;
783 memset(rec, 0, sizeof(*rec));
786 rec->data_len = recovery_size;
787 rec->rec_len = recovery_max_size;
788 rec->key_len = old_map_size;
791 /* build the recovery data into a single blob to allow us to do a single
792 large write, which should be more efficient */
793 p = data + sizeof(*rec);
794 for (i=0;i<tdb->transaction->num_blocks;i++) {
798 if (tdb->transaction->blocks[i] == NULL) {
802 offset = i * tdb->transaction->block_size;
803 length = tdb->transaction->block_size;
804 if (i == tdb->transaction->num_blocks-1) {
805 length = tdb->transaction->last_block_size;
808 if (offset >= old_map_size) {
811 if (offset + length > tdb->transaction->old_map_size) {
812 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
814 tdb->ecode = TDB_ERR_CORRUPT;
817 memcpy(p, &offset, 4);
818 memcpy(p+4, &length, 4);
822 /* the recovery area contains the old data, not the
823 new data, so we have to call the original tdb_read
825 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
827 tdb->ecode = TDB_ERR_IO;
834 tailer = sizeof(*rec) + recovery_max_size;
835 memcpy(p, &tailer, 4);
838 /* write the recovery data to the recovery area */
839 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
840 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
842 tdb->ecode = TDB_ERR_IO;
845 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
846 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
848 tdb->ecode = TDB_ERR_IO;
852 /* as we don't have ordered writes, we have to sync the recovery
853 data before we update the magic to indicate that the recovery
855 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
862 magic = TDB_RECOVERY_MAGIC;
865 *magic_offset = recovery_offset + offsetof(struct list_struct, magic);
867 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
868 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
869 tdb->ecode = TDB_ERR_IO;
872 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
873 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
874 tdb->ecode = TDB_ERR_IO;
878 /* ensure the recovery magic marker is on disk */
879 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
886 static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
888 const struct tdb_methods *methods;
890 if (tdb->transaction == NULL) {
891 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
895 if (tdb->transaction->prepared) {
896 tdb->ecode = TDB_ERR_EINVAL;
897 tdb_transaction_cancel(tdb);
898 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
902 if (tdb->transaction->transaction_error) {
903 tdb->ecode = TDB_ERR_IO;
904 tdb_transaction_cancel_internal(tdb);
905 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
910 if (tdb->transaction->nesting != 0) {
911 tdb->transaction->nesting--;
916 /* store seqnum now, before reading becomes illegal. */
917 tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &tdb->transaction_prepare_seqnum);
920 /* check for a null transaction */
921 if (tdb->transaction->blocks == NULL) {
925 methods = tdb->transaction->io_methods;
927 /* if there are any locks pending then the caller has not
928 nested their locks properly, so fail the transaction */
929 if (tdb->num_locks || tdb->global_lock.count) {
930 tdb->ecode = TDB_ERR_LOCK;
931 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
932 tdb_transaction_cancel_internal(tdb);
936 /* upgrade the main transaction lock region to a write lock */
937 if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
938 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
939 tdb->ecode = TDB_ERR_LOCK;
940 tdb_transaction_cancel_internal(tdb);
944 /* get the global lock - this prevents new users attaching to the database
946 if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
947 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
948 tdb->ecode = TDB_ERR_LOCK;
949 tdb_transaction_cancel_internal(tdb);
953 if (!(tdb->flags & TDB_NOSYNC)) {
954 /* write the recovery data to the end of the file */
955 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
956 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
957 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
958 tdb_transaction_cancel_internal(tdb);
963 tdb->transaction->prepared = true;
965 /* expand the file to the new size if needed */
966 if (tdb->map_size != tdb->transaction->old_map_size) {
967 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
969 tdb->transaction->old_map_size) == -1) {
970 tdb->ecode = TDB_ERR_IO;
971 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
972 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
973 tdb_transaction_cancel_internal(tdb);
976 tdb->map_size = tdb->transaction->old_map_size;
977 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
980 /* Keep the global lock until the actual commit */
986 prepare to commit the current transaction
988 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
990 tdb_trace(tdb, "tdb_transaction_prepare_commit");
991 return tdb_transaction_prepare_commit_internal(tdb);
995 commit the current transaction
997 int tdb_transaction_commit(struct tdb_context *tdb)
999 const struct tdb_methods *methods;
1003 if (tdb->transaction == NULL) {
1004 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
1008 /* If we've prepared, can't read seqnum. */
1009 if (tdb->transaction->prepared) {
1010 tdb_trace_seqnum(tdb, tdb->transaction_prepare_seqnum,
1011 "tdb_transaction_commit");
1013 tdb_trace(tdb, "tdb_transaction_commit");
1016 if (tdb->transaction->transaction_error) {
1017 tdb->ecode = TDB_ERR_IO;
1018 tdb_transaction_cancel(tdb);
1019 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1024 if (tdb->transaction->nesting != 0) {
1025 tdb->transaction->nesting--;
1029 /* check for a null transaction */
1030 if (tdb->transaction->blocks == NULL) {
1031 tdb_transaction_cancel_internal(tdb);
1035 if (!tdb->transaction->prepared) {
1036 int ret = tdb_transaction_prepare_commit_internal(tdb);
1041 methods = tdb->transaction->io_methods;
1043 /* perform all the writes */
1044 for (i=0;i<tdb->transaction->num_blocks;i++) {
1048 if (tdb->transaction->blocks[i] == NULL) {
1052 offset = i * tdb->transaction->block_size;
1053 length = tdb->transaction->block_size;
1054 if (i == tdb->transaction->num_blocks-1) {
1055 length = tdb->transaction->last_block_size;
1058 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1059 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1061 /* we've overwritten part of the data and
1062 possibly expanded the file, so we need to
1063 run the crash recovery code */
1064 tdb->methods = methods;
1065 tdb_transaction_recover(tdb);
1067 tdb_transaction_cancel_internal(tdb);
1068 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1070 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1073 SAFE_FREE(tdb->transaction->blocks[i]);
1076 SAFE_FREE(tdb->transaction->blocks);
1077 tdb->transaction->num_blocks = 0;
1079 /* ensure the new data is on disk */
1080 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1084 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1087 TODO: maybe write to some dummy hdr field, or write to magic
1088 offset without mmap, before the last sync, instead of the
1092 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1093 don't change the mtime of the file, this means the file may
1094 not be backed up (as tdb rounding to block sizes means that
1095 file size changes are quite rare too). The following forces
1096 mtime changes when a transaction completes */
1098 utime(tdb->name, NULL);
1101 need_repack = tdb->transaction->need_repack;
1103 /* use a transaction cancel to free memory and remove the
1104 transaction locks */
1105 tdb_transaction_cancel_internal(tdb);
1108 return tdb_repack(tdb);
1116 recover from an aborted transaction. Must be called with exclusive
1117 database write access already established (including the global
1118 lock to prevent new processes attaching)
1120 int tdb_transaction_recover(struct tdb_context *tdb)
1122 tdb_off_t recovery_head, recovery_eof;
1123 unsigned char *data, *p;
1125 struct list_struct rec;
1127 /* find the recovery area */
1128 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1129 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1130 tdb->ecode = TDB_ERR_IO;
1134 if (recovery_head == 0) {
1135 /* we have never allocated a recovery record */
1139 /* read the recovery record */
1140 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1141 sizeof(rec), DOCONV()) == -1) {
1142 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1143 tdb->ecode = TDB_ERR_IO;
1147 if (rec.magic != TDB_RECOVERY_MAGIC) {
1148 /* there is no valid recovery data */
1152 if (tdb->read_only) {
1153 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1154 tdb->ecode = TDB_ERR_CORRUPT;
1158 recovery_eof = rec.key_len;
1160 data = (unsigned char *)malloc(rec.data_len);
1162 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1163 tdb->ecode = TDB_ERR_OOM;
1167 /* read the full recovery data */
1168 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1169 rec.data_len, 0) == -1) {
1170 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1171 tdb->ecode = TDB_ERR_IO;
1175 /* recover the file data */
1177 while (p+8 < data + rec.data_len) {
1183 memcpy(&len, p+4, 4);
1185 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1187 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1188 tdb->ecode = TDB_ERR_IO;
1196 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1197 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1198 tdb->ecode = TDB_ERR_IO;
1202 /* if the recovery area is after the recovered eof then remove it */
1203 if (recovery_eof <= recovery_head) {
1204 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1205 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1206 tdb->ecode = TDB_ERR_IO;
1211 /* remove the recovery magic */
1212 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic),
1214 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1215 tdb->ecode = TDB_ERR_IO;
1219 /* reduce the file size to the old size */
1221 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1222 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1223 tdb->ecode = TDB_ERR_IO;
1226 tdb->map_size = recovery_eof;
1229 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1230 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1231 tdb->ecode = TDB_ERR_IO;
1235 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",