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 open 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;
411 static const struct tdb_methods transaction_methods = {
414 transaction_next_hash_chain,
416 transaction_expand_file,
421 start a tdb transaction. No token is returned, as only a single
422 transaction is allowed to be pending per tdb_context
424 int tdb_transaction_start(struct tdb_context *tdb)
426 /* some sanity checks */
427 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
428 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
429 tdb->ecode = TDB_ERR_EINVAL;
433 /* cope with nested tdb_transaction_start() calls */
434 if (tdb->transaction != NULL) {
435 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
436 tdb->ecode = TDB_ERR_NESTING;
439 tdb->transaction->nesting++;
440 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
441 tdb->transaction->nesting));
445 if (tdb_have_extra_locks(tdb)) {
446 /* the caller must not have any locks when starting a
447 transaction as otherwise we'll be screwed by lack
448 of nested locks in posix */
449 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
450 tdb->ecode = TDB_ERR_LOCK;
454 if (tdb->travlocks.next != NULL) {
455 /* you cannot use transactions inside a traverse (although you can use
456 traverse inside a transaction) as otherwise you can end up with
458 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
459 tdb->ecode = TDB_ERR_LOCK;
463 tdb->transaction = (struct tdb_transaction *)
464 calloc(sizeof(struct tdb_transaction), 1);
465 if (tdb->transaction == NULL) {
466 tdb->ecode = TDB_ERR_OOM;
470 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
471 tdb->transaction->block_size = tdb->page_size;
473 /* get the transaction write lock. This is a blocking lock. As
474 discussed with Volker, there are a number of ways we could
475 make this async, which we will probably do in the future */
476 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
477 SAFE_FREE(tdb->transaction->blocks);
478 SAFE_FREE(tdb->transaction);
482 /* get a read lock from the freelist to the end of file. This
483 is upgraded to a write lock during the commit */
484 if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
485 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
486 goto fail_allrecord_lock;
489 /* setup a copy of the hash table heads so the hash scan in
490 traverse can be fast */
491 tdb->transaction->hash_heads = (uint32_t *)
492 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
493 if (tdb->transaction->hash_heads == NULL) {
494 tdb->ecode = TDB_ERR_OOM;
497 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
498 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
499 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
500 tdb->ecode = TDB_ERR_IO;
504 /* make sure we know about any file expansions already done by
506 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
507 tdb->transaction->old_map_size = tdb->map_size;
509 /* finally hook the io methods, replacing them with
510 transaction specific methods */
511 tdb->transaction->io_methods = tdb->methods;
512 tdb->methods = &transaction_methods;
514 /* Trace at the end, so we get sequence number correct. */
515 tdb_trace(tdb, "tdb_transaction_start");
519 tdb_allrecord_unlock(tdb, F_RDLCK, false);
521 tdb_transaction_unlock(tdb, F_WRLCK);
522 SAFE_FREE(tdb->transaction->blocks);
523 SAFE_FREE(tdb->transaction->hash_heads);
524 SAFE_FREE(tdb->transaction);
532 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
534 if (tdb->flags & TDB_NOSYNC) {
538 if (fdatasync(tdb->fd) != 0) {
539 tdb->ecode = TDB_ERR_IO;
540 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
545 tdb_off_t moffset = offset & ~(tdb->page_size-1);
546 if (msync(moffset + (char *)tdb->map_ptr,
547 length + (offset - moffset), MS_SYNC) != 0) {
548 tdb->ecode = TDB_ERR_IO;
549 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
559 static int _tdb_transaction_cancel(struct tdb_context *tdb)
563 if (tdb->transaction == NULL) {
564 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
568 if (tdb->transaction->nesting != 0) {
569 tdb->transaction->transaction_error = 1;
570 tdb->transaction->nesting--;
574 tdb->map_size = tdb->transaction->old_map_size;
576 /* free all the transaction blocks */
577 for (i=0;i<tdb->transaction->num_blocks;i++) {
578 if (tdb->transaction->blocks[i] != NULL) {
579 free(tdb->transaction->blocks[i]);
582 SAFE_FREE(tdb->transaction->blocks);
584 if (tdb->transaction->magic_offset) {
585 const struct tdb_methods *methods = tdb->transaction->io_methods;
586 const uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
588 /* remove the recovery marker */
589 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
590 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
591 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
596 /* This also removes the OPEN_LOCK, if we have it. */
597 tdb_release_transaction_locks(tdb);
599 /* restore the normal io methods */
600 tdb->methods = tdb->transaction->io_methods;
602 SAFE_FREE(tdb->transaction->hash_heads);
603 SAFE_FREE(tdb->transaction);
609 cancel the current transaction
611 int tdb_transaction_cancel(struct tdb_context *tdb)
613 tdb_trace(tdb, "tdb_transaction_cancel");
614 return _tdb_transaction_cancel(tdb);
618 work out how much space the linearised recovery data will consume
620 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
622 tdb_len_t recovery_size = 0;
625 recovery_size = sizeof(uint32_t);
626 for (i=0;i<tdb->transaction->num_blocks;i++) {
627 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
630 if (tdb->transaction->blocks[i] == NULL) {
633 recovery_size += 2*sizeof(tdb_off_t);
634 if (i == tdb->transaction->num_blocks-1) {
635 recovery_size += tdb->transaction->last_block_size;
637 recovery_size += tdb->transaction->block_size;
641 return recovery_size;
645 allocate the recovery area, or use an existing recovery area if it is
648 static int tdb_recovery_allocate(struct tdb_context *tdb,
649 tdb_len_t *recovery_size,
650 tdb_off_t *recovery_offset,
651 tdb_len_t *recovery_max_size)
653 struct tdb_record rec;
654 const struct tdb_methods *methods = tdb->transaction->io_methods;
655 tdb_off_t recovery_head;
657 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
658 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
664 if (recovery_head != 0) {
665 if (methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
666 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
669 /* ignore invalid recovery regions: can happen in crash */
670 if (rec.magic != TDB_RECOVERY_MAGIC &&
671 rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
676 *recovery_size = tdb_recovery_size(tdb);
678 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
679 /* it fits in the existing area */
680 *recovery_max_size = rec.rec_len;
681 *recovery_offset = recovery_head;
685 /* we need to free up the old recovery area, then allocate a
686 new one at the end of the file. Note that we cannot use
687 tdb_allocate() to allocate the new one as that might return
688 us an area that is being currently used (as of the start of
690 if (recovery_head != 0) {
691 if (tdb_free(tdb, recovery_head, &rec) == -1) {
692 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
697 /* the tdb_free() call might have increased the recovery size */
698 *recovery_size = tdb_recovery_size(tdb);
700 /* round up to a multiple of page size */
701 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
702 *recovery_offset = tdb->map_size;
703 recovery_head = *recovery_offset;
705 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
706 (tdb->map_size - tdb->transaction->old_map_size) +
707 sizeof(rec) + *recovery_max_size) == -1) {
708 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
712 /* remap the file (if using mmap) */
713 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
715 /* we have to reset the old map size so that we don't try to expand the file
716 again in the transaction commit, which would destroy the recovery area */
717 tdb->transaction->old_map_size = tdb->map_size;
719 /* write the recovery header offset and sync - we can sync without a race here
720 as the magic ptr in the recovery record has not been set */
721 CONVERT(recovery_head);
722 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
723 &recovery_head, sizeof(tdb_off_t)) == -1) {
724 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
727 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
728 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
737 setup the recovery data that will be used on a crash during commit
739 static int transaction_setup_recovery(struct tdb_context *tdb,
740 tdb_off_t *magic_offset)
742 tdb_len_t recovery_size;
743 unsigned char *data, *p;
744 const struct tdb_methods *methods = tdb->transaction->io_methods;
745 struct tdb_record *rec;
746 tdb_off_t recovery_offset, recovery_max_size;
747 tdb_off_t old_map_size = tdb->transaction->old_map_size;
748 uint32_t magic, tailer;
752 check that the recovery area has enough space
754 if (tdb_recovery_allocate(tdb, &recovery_size,
755 &recovery_offset, &recovery_max_size) == -1) {
759 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
761 tdb->ecode = TDB_ERR_OOM;
765 rec = (struct tdb_record *)data;
766 memset(rec, 0, sizeof(*rec));
768 rec->magic = TDB_RECOVERY_INVALID_MAGIC;
769 rec->data_len = recovery_size;
770 rec->rec_len = recovery_max_size;
771 rec->key_len = old_map_size;
774 /* build the recovery data into a single blob to allow us to do a single
775 large write, which should be more efficient */
776 p = data + sizeof(*rec);
777 for (i=0;i<tdb->transaction->num_blocks;i++) {
781 if (tdb->transaction->blocks[i] == NULL) {
785 offset = i * tdb->transaction->block_size;
786 length = tdb->transaction->block_size;
787 if (i == tdb->transaction->num_blocks-1) {
788 length = tdb->transaction->last_block_size;
791 if (offset >= old_map_size) {
794 if (offset + length > tdb->transaction->old_map_size) {
795 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
797 tdb->ecode = TDB_ERR_CORRUPT;
800 memcpy(p, &offset, 4);
801 memcpy(p+4, &length, 4);
805 /* the recovery area contains the old data, not the
806 new data, so we have to call the original tdb_read
808 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
810 tdb->ecode = TDB_ERR_IO;
817 tailer = sizeof(*rec) + recovery_max_size;
818 memcpy(p, &tailer, 4);
821 /* write the recovery data to the recovery area */
822 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
823 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
825 tdb->ecode = TDB_ERR_IO;
828 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
829 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
831 tdb->ecode = TDB_ERR_IO;
835 /* as we don't have ordered writes, we have to sync the recovery
836 data before we update the magic to indicate that the recovery
838 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
845 magic = TDB_RECOVERY_MAGIC;
848 *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
850 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
851 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
852 tdb->ecode = TDB_ERR_IO;
855 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
856 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
857 tdb->ecode = TDB_ERR_IO;
861 /* ensure the recovery magic marker is on disk */
862 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
869 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
871 const struct tdb_methods *methods;
873 if (tdb->transaction == NULL) {
874 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
878 if (tdb->transaction->prepared) {
879 tdb->ecode = TDB_ERR_EINVAL;
880 _tdb_transaction_cancel(tdb);
881 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
885 if (tdb->transaction->transaction_error) {
886 tdb->ecode = TDB_ERR_IO;
887 _tdb_transaction_cancel(tdb);
888 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
893 if (tdb->transaction->nesting != 0) {
897 /* check for a null transaction */
898 if (tdb->transaction->blocks == NULL) {
902 methods = tdb->transaction->io_methods;
904 /* if there are any locks pending then the caller has not
905 nested their locks properly, so fail the transaction */
906 if (tdb_have_extra_locks(tdb)) {
907 tdb->ecode = TDB_ERR_LOCK;
908 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
909 _tdb_transaction_cancel(tdb);
913 /* upgrade the main transaction lock region to a write lock */
914 if (tdb_allrecord_upgrade(tdb) == -1) {
915 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
916 _tdb_transaction_cancel(tdb);
920 /* get the open lock - this prevents new users attaching to the database
922 if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
923 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
924 _tdb_transaction_cancel(tdb);
928 if (!(tdb->flags & TDB_NOSYNC)) {
929 /* write the recovery data to the end of the file */
930 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
931 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
932 _tdb_transaction_cancel(tdb);
937 tdb->transaction->prepared = true;
939 /* expand the file to the new size if needed */
940 if (tdb->map_size != tdb->transaction->old_map_size) {
941 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
943 tdb->transaction->old_map_size) == -1) {
944 tdb->ecode = TDB_ERR_IO;
945 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
946 _tdb_transaction_cancel(tdb);
949 tdb->map_size = tdb->transaction->old_map_size;
950 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
953 /* Keep the open lock until the actual commit */
959 prepare to commit the current transaction
961 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
963 tdb_trace(tdb, "tdb_transaction_prepare_commit");
964 return _tdb_transaction_prepare_commit(tdb);
968 commit the current transaction
970 int tdb_transaction_commit(struct tdb_context *tdb)
972 const struct tdb_methods *methods;
976 if (tdb->transaction == NULL) {
977 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
981 tdb_trace(tdb, "tdb_transaction_commit");
983 if (tdb->transaction->transaction_error) {
984 tdb->ecode = TDB_ERR_IO;
985 _tdb_transaction_cancel(tdb);
986 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
991 if (tdb->transaction->nesting != 0) {
992 tdb->transaction->nesting--;
996 /* check for a null transaction */
997 if (tdb->transaction->blocks == NULL) {
998 _tdb_transaction_cancel(tdb);
1002 if (!tdb->transaction->prepared) {
1003 int ret = _tdb_transaction_prepare_commit(tdb);
1008 methods = tdb->transaction->io_methods;
1010 /* perform all the writes */
1011 for (i=0;i<tdb->transaction->num_blocks;i++) {
1015 if (tdb->transaction->blocks[i] == NULL) {
1019 offset = i * tdb->transaction->block_size;
1020 length = tdb->transaction->block_size;
1021 if (i == tdb->transaction->num_blocks-1) {
1022 length = tdb->transaction->last_block_size;
1025 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1026 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1028 /* we've overwritten part of the data and
1029 possibly expanded the file, so we need to
1030 run the crash recovery code */
1031 tdb->methods = methods;
1032 tdb_transaction_recover(tdb);
1034 _tdb_transaction_cancel(tdb);
1036 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1039 SAFE_FREE(tdb->transaction->blocks[i]);
1042 SAFE_FREE(tdb->transaction->blocks);
1043 tdb->transaction->num_blocks = 0;
1045 /* ensure the new data is on disk */
1046 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1051 TODO: maybe write to some dummy hdr field, or write to magic
1052 offset without mmap, before the last sync, instead of the
1056 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1057 don't change the mtime of the file, this means the file may
1058 not be backed up (as tdb rounding to block sizes means that
1059 file size changes are quite rare too). The following forces
1060 mtime changes when a transaction completes */
1062 utime(tdb->name, NULL);
1065 need_repack = tdb->transaction->need_repack;
1067 /* use a transaction cancel to free memory and remove the
1068 transaction locks */
1069 _tdb_transaction_cancel(tdb);
1072 return tdb_repack(tdb);
1080 recover from an aborted transaction. Must be called with exclusive
1081 database write access already established (including the open
1082 lock to prevent new processes attaching)
1084 int tdb_transaction_recover(struct tdb_context *tdb)
1086 tdb_off_t recovery_head, recovery_eof;
1087 unsigned char *data, *p;
1089 struct tdb_record rec;
1091 /* find the recovery area */
1092 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1093 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1094 tdb->ecode = TDB_ERR_IO;
1098 if (recovery_head == 0) {
1099 /* we have never allocated a recovery record */
1103 /* read the recovery record */
1104 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1105 sizeof(rec), DOCONV()) == -1) {
1106 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1107 tdb->ecode = TDB_ERR_IO;
1111 if (rec.magic != TDB_RECOVERY_MAGIC) {
1112 /* there is no valid recovery data */
1116 if (tdb->read_only) {
1117 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1118 tdb->ecode = TDB_ERR_CORRUPT;
1122 recovery_eof = rec.key_len;
1124 data = (unsigned char *)malloc(rec.data_len);
1126 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1127 tdb->ecode = TDB_ERR_OOM;
1131 /* read the full recovery data */
1132 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1133 rec.data_len, 0) == -1) {
1134 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1135 tdb->ecode = TDB_ERR_IO;
1139 /* recover the file data */
1141 while (p+8 < data + rec.data_len) {
1147 memcpy(&len, p+4, 4);
1149 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1151 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1152 tdb->ecode = TDB_ERR_IO;
1160 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1161 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1162 tdb->ecode = TDB_ERR_IO;
1166 /* if the recovery area is after the recovered eof then remove it */
1167 if (recovery_eof <= recovery_head) {
1168 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1169 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1170 tdb->ecode = TDB_ERR_IO;
1175 /* remove the recovery magic */
1176 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
1178 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1179 tdb->ecode = TDB_ERR_IO;
1183 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1184 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1185 tdb->ecode = TDB_ERR_IO;
1189 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",
1196 /* Any I/O failures we say "needs recovery". */
1197 bool tdb_needs_recovery(struct tdb_context *tdb)
1199 tdb_off_t recovery_head;
1200 struct tdb_record rec;
1202 /* find the recovery area */
1203 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1207 if (recovery_head == 0) {
1208 /* we have never allocated a recovery record */
1212 /* read the recovery record */
1213 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1214 sizeof(rec), DOCONV()) == -1) {
1218 return (rec.magic == TDB_RECOVERY_MAGIC);