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;
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)
418 /* FIXME: We actually grab the open lock during a transaction. */
419 if (offset == OPEN_LOCK)
420 return tdb_brlock(tdb, rw_type, offset, len, flags);
424 static int transaction_brunlock(struct tdb_context *tdb,
425 int rw_type, tdb_off_t offset, size_t len)
430 static const struct tdb_methods transaction_methods = {
433 transaction_next_hash_chain,
435 transaction_expand_file,
443 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
445 if (tdb->flags & TDB_NOSYNC) {
449 if (fsync(tdb->fd) != 0) {
450 tdb->ecode = TDB_ERR_IO;
451 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
456 tdb_off_t moffset = offset & ~(tdb->page_size-1);
457 if (msync(moffset + (char *)tdb->map_ptr,
458 length + (offset - moffset), MS_SYNC) != 0) {
459 tdb->ecode = TDB_ERR_IO;
460 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
470 static int _tdb_transaction_cancel(struct tdb_context *tdb)
474 if (tdb->transaction == NULL) {
475 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
479 if (tdb->transaction->nesting != 0) {
480 tdb->transaction->transaction_error = 1;
481 tdb->transaction->nesting--;
485 tdb->map_size = tdb->transaction->old_map_size;
487 /* free all the transaction blocks */
488 for (i=0;i<tdb->transaction->num_blocks;i++) {
489 if (tdb->transaction->blocks[i] != NULL) {
490 free(tdb->transaction->blocks[i]);
493 SAFE_FREE(tdb->transaction->blocks);
495 if (tdb->transaction->magic_offset) {
496 const struct tdb_methods *methods = tdb->transaction->io_methods;
497 uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
499 /* remove the recovery marker */
500 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
501 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
502 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
507 /* This also removes the OPEN_LOCK, if we have it. */
508 tdb_release_extra_locks(tdb);
510 /* restore the normal io methods */
511 tdb->methods = tdb->transaction->io_methods;
513 tdb_transaction_unlock(tdb, F_WRLCK);
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 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
536 tdb->ecode = TDB_ERR_NESTING;
539 tdb_trace(tdb, "tdb_transaction_start");
540 tdb->transaction->nesting++;
541 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
542 tdb->transaction->nesting));
546 if (tdb_have_extra_locks(tdb)) {
547 /* the caller must not have any locks when starting a
548 transaction as otherwise we'll be screwed by lack
549 of nested locks in posix */
550 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
551 tdb->ecode = TDB_ERR_LOCK;
555 if (tdb->travlocks.next != NULL) {
556 /* you cannot use transactions inside a traverse (although you can use
557 traverse inside a transaction) as otherwise you can end up with
559 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
560 tdb->ecode = TDB_ERR_LOCK;
564 tdb->transaction = (struct tdb_transaction *)
565 calloc(sizeof(struct tdb_transaction), 1);
566 if (tdb->transaction == NULL) {
567 tdb->ecode = TDB_ERR_OOM;
571 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
572 tdb->transaction->block_size = tdb->page_size;
574 /* get the transaction write lock. This is a blocking lock. As
575 discussed with Volker, there are a number of ways we could
576 make this async, which we will probably do in the future */
577 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
578 SAFE_FREE(tdb->transaction->blocks);
579 SAFE_FREE(tdb->transaction);
583 /* get a read lock from the freelist to the end of file. This
584 is upgraded to a write lock during the commit */
585 if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
586 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
587 goto fail_allrecord_lock;
590 /* setup a copy of the hash table heads so the hash scan in
591 traverse can be fast */
592 tdb->transaction->hash_heads = (uint32_t *)
593 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
594 if (tdb->transaction->hash_heads == NULL) {
595 tdb->ecode = TDB_ERR_OOM;
598 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
599 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
600 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
601 tdb->ecode = TDB_ERR_IO;
605 /* make sure we know about any file expansions already done by
607 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
608 tdb->transaction->old_map_size = tdb->map_size;
610 /* finally hook the io methods, replacing them with
611 transaction specific methods */
612 tdb->transaction->io_methods = tdb->methods;
613 tdb->methods = &transaction_methods;
615 /* Trace at the end, so we get sequence number correct. */
616 tdb_trace(tdb, "tdb_transaction_start");
620 tdb_allrecord_unlock(tdb, F_RDLCK, false);
622 tdb_transaction_unlock(tdb, F_WRLCK);
623 SAFE_FREE(tdb->transaction->blocks);
624 SAFE_FREE(tdb->transaction->hash_heads);
625 SAFE_FREE(tdb->transaction);
631 cancel the current transaction
633 int tdb_transaction_cancel(struct tdb_context *tdb)
635 tdb_trace(tdb, "tdb_transaction_cancel");
636 return _tdb_transaction_cancel(tdb);
640 work out how much space the linearised recovery data will consume
642 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
644 tdb_len_t recovery_size = 0;
647 recovery_size = sizeof(uint32_t);
648 for (i=0;i<tdb->transaction->num_blocks;i++) {
649 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
652 if (tdb->transaction->blocks[i] == NULL) {
655 recovery_size += 2*sizeof(tdb_off_t);
656 if (i == tdb->transaction->num_blocks-1) {
657 recovery_size += tdb->transaction->last_block_size;
659 recovery_size += tdb->transaction->block_size;
663 return recovery_size;
667 allocate the recovery area, or use an existing recovery area if it is
670 static int tdb_recovery_allocate(struct tdb_context *tdb,
671 tdb_len_t *recovery_size,
672 tdb_off_t *recovery_offset,
673 tdb_len_t *recovery_max_size)
675 struct tdb_record rec;
676 const struct tdb_methods *methods = tdb->transaction->io_methods;
677 tdb_off_t recovery_head;
679 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
680 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
686 if (recovery_head != 0 &&
687 methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
688 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
692 *recovery_size = tdb_recovery_size(tdb);
694 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
695 /* it fits in the existing area */
696 *recovery_max_size = rec.rec_len;
697 *recovery_offset = recovery_head;
701 /* we need to free up the old recovery area, then allocate a
702 new one at the end of the file. Note that we cannot use
703 tdb_allocate() to allocate the new one as that might return
704 us an area that is being currently used (as of the start of
706 if (recovery_head != 0) {
707 if (tdb_free(tdb, recovery_head, &rec) == -1) {
708 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
713 /* the tdb_free() call might have increased the recovery size */
714 *recovery_size = tdb_recovery_size(tdb);
716 /* round up to a multiple of page size */
717 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
718 *recovery_offset = tdb->map_size;
719 recovery_head = *recovery_offset;
721 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
722 (tdb->map_size - tdb->transaction->old_map_size) +
723 sizeof(rec) + *recovery_max_size) == -1) {
724 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
728 /* remap the file (if using mmap) */
729 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
731 /* we have to reset the old map size so that we don't try to expand the file
732 again in the transaction commit, which would destroy the recovery area */
733 tdb->transaction->old_map_size = tdb->map_size;
735 /* write the recovery header offset and sync - we can sync without a race here
736 as the magic ptr in the recovery record has not been set */
737 CONVERT(recovery_head);
738 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
739 &recovery_head, sizeof(tdb_off_t)) == -1) {
740 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
743 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
744 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
753 setup the recovery data that will be used on a crash during commit
755 static int transaction_setup_recovery(struct tdb_context *tdb,
756 tdb_off_t *magic_offset)
758 tdb_len_t recovery_size;
759 unsigned char *data, *p;
760 const struct tdb_methods *methods = tdb->transaction->io_methods;
761 struct tdb_record *rec;
762 tdb_off_t recovery_offset, recovery_max_size;
763 tdb_off_t old_map_size = tdb->transaction->old_map_size;
764 uint32_t magic, tailer;
768 check that the recovery area has enough space
770 if (tdb_recovery_allocate(tdb, &recovery_size,
771 &recovery_offset, &recovery_max_size) == -1) {
775 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
777 tdb->ecode = TDB_ERR_OOM;
781 rec = (struct tdb_record *)data;
782 memset(rec, 0, sizeof(*rec));
784 rec->magic = TDB_RECOVERY_INVALID_MAGIC;
785 rec->data_len = recovery_size;
786 rec->rec_len = recovery_max_size;
787 rec->key_len = old_map_size;
790 /* build the recovery data into a single blob to allow us to do a single
791 large write, which should be more efficient */
792 p = data + sizeof(*rec);
793 for (i=0;i<tdb->transaction->num_blocks;i++) {
797 if (tdb->transaction->blocks[i] == NULL) {
801 offset = i * tdb->transaction->block_size;
802 length = tdb->transaction->block_size;
803 if (i == tdb->transaction->num_blocks-1) {
804 length = tdb->transaction->last_block_size;
807 if (offset >= old_map_size) {
810 if (offset + length > tdb->transaction->old_map_size) {
811 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
813 tdb->ecode = TDB_ERR_CORRUPT;
816 memcpy(p, &offset, 4);
817 memcpy(p+4, &length, 4);
821 /* the recovery area contains the old data, not the
822 new data, so we have to call the original tdb_read
824 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
826 tdb->ecode = TDB_ERR_IO;
833 tailer = sizeof(*rec) + recovery_max_size;
834 memcpy(p, &tailer, 4);
837 /* write the recovery data to the recovery area */
838 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
839 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
841 tdb->ecode = TDB_ERR_IO;
844 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
845 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
847 tdb->ecode = TDB_ERR_IO;
851 /* as we don't have ordered writes, we have to sync the recovery
852 data before we update the magic to indicate that the recovery
854 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
861 magic = TDB_RECOVERY_MAGIC;
864 *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
866 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
867 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
868 tdb->ecode = TDB_ERR_IO;
871 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
872 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
873 tdb->ecode = TDB_ERR_IO;
877 /* ensure the recovery magic marker is on disk */
878 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
885 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
887 const struct tdb_methods *methods;
889 if (tdb->transaction == NULL) {
890 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
894 if (tdb->transaction->prepared) {
895 tdb->ecode = TDB_ERR_EINVAL;
896 _tdb_transaction_cancel(tdb);
897 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
901 if (tdb->transaction->transaction_error) {
902 tdb->ecode = TDB_ERR_IO;
903 _tdb_transaction_cancel(tdb);
904 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
909 if (tdb->transaction->nesting != 0) {
910 tdb->transaction->nesting--;
914 /* check for a null transaction */
915 if (tdb->transaction->blocks == NULL) {
919 methods = tdb->transaction->io_methods;
921 /* if there are any locks pending then the caller has not
922 nested their locks properly, so fail the transaction */
923 if (tdb_have_extra_locks(tdb)) {
924 tdb->ecode = TDB_ERR_LOCK;
925 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
926 _tdb_transaction_cancel(tdb);
930 /* upgrade the main transaction lock region to a write lock */
931 if (tdb_allrecord_upgrade(tdb) == -1) {
932 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
933 _tdb_transaction_cancel(tdb);
937 /* get the open lock - this prevents new users attaching to the database
939 if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
940 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
941 _tdb_transaction_cancel(tdb);
945 if (!(tdb->flags & TDB_NOSYNC)) {
946 /* write the recovery data to the end of the file */
947 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
948 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
949 _tdb_transaction_cancel(tdb);
954 tdb->transaction->prepared = true;
956 /* expand the file to the new size if needed */
957 if (tdb->map_size != tdb->transaction->old_map_size) {
958 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
960 tdb->transaction->old_map_size) == -1) {
961 tdb->ecode = TDB_ERR_IO;
962 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
963 _tdb_transaction_cancel(tdb);
966 tdb->map_size = tdb->transaction->old_map_size;
967 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
970 /* Keep the open lock until the actual commit */
976 prepare to commit the current transaction
978 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
980 tdb_trace(tdb, "tdb_transaction_prepare_commit");
981 return _tdb_transaction_prepare_commit(tdb);
985 commit the current transaction
987 int tdb_transaction_commit(struct tdb_context *tdb)
989 const struct tdb_methods *methods;
993 if (tdb->transaction == NULL) {
994 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
998 tdb_trace(tdb, "tdb_transaction_commit");
1000 if (tdb->transaction->transaction_error) {
1001 tdb->ecode = TDB_ERR_IO;
1002 tdb_transaction_cancel(tdb);
1003 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1008 if (tdb->transaction->nesting != 0) {
1009 tdb->transaction->nesting--;
1013 /* check for a null transaction */
1014 if (tdb->transaction->blocks == NULL) {
1015 _tdb_transaction_cancel(tdb);
1019 if (!tdb->transaction->prepared) {
1020 int ret = _tdb_transaction_prepare_commit(tdb);
1025 methods = tdb->transaction->io_methods;
1027 /* perform all the writes */
1028 for (i=0;i<tdb->transaction->num_blocks;i++) {
1032 if (tdb->transaction->blocks[i] == NULL) {
1036 offset = i * tdb->transaction->block_size;
1037 length = tdb->transaction->block_size;
1038 if (i == tdb->transaction->num_blocks-1) {
1039 length = tdb->transaction->last_block_size;
1042 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1043 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1045 /* we've overwritten part of the data and
1046 possibly expanded the file, so we need to
1047 run the crash recovery code */
1048 tdb->methods = methods;
1049 tdb_transaction_recover(tdb);
1051 _tdb_transaction_cancel(tdb);
1053 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1056 SAFE_FREE(tdb->transaction->blocks[i]);
1059 SAFE_FREE(tdb->transaction->blocks);
1060 tdb->transaction->num_blocks = 0;
1062 /* ensure the new data is on disk */
1063 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1068 TODO: maybe write to some dummy hdr field, or write to magic
1069 offset without mmap, before the last sync, instead of the
1073 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1074 don't change the mtime of the file, this means the file may
1075 not be backed up (as tdb rounding to block sizes means that
1076 file size changes are quite rare too). The following forces
1077 mtime changes when a transaction completes */
1079 utime(tdb->name, NULL);
1082 need_repack = tdb->transaction->need_repack;
1084 /* use a transaction cancel to free memory and remove the
1085 transaction locks */
1086 _tdb_transaction_cancel(tdb);
1089 return tdb_repack(tdb);
1097 recover from an aborted transaction. Must be called with exclusive
1098 database write access already established (including the open
1099 lock to prevent new processes attaching)
1101 int tdb_transaction_recover(struct tdb_context *tdb)
1103 tdb_off_t recovery_head, recovery_eof;
1104 unsigned char *data, *p;
1106 struct tdb_record rec;
1108 /* find the recovery area */
1109 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1110 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1111 tdb->ecode = TDB_ERR_IO;
1115 if (recovery_head == 0) {
1116 /* we have never allocated a recovery record */
1120 /* read the recovery record */
1121 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1122 sizeof(rec), DOCONV()) == -1) {
1123 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1124 tdb->ecode = TDB_ERR_IO;
1128 if (rec.magic != TDB_RECOVERY_MAGIC) {
1129 /* there is no valid recovery data */
1133 if (tdb->read_only) {
1134 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1135 tdb->ecode = TDB_ERR_CORRUPT;
1139 recovery_eof = rec.key_len;
1141 data = (unsigned char *)malloc(rec.data_len);
1143 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1144 tdb->ecode = TDB_ERR_OOM;
1148 /* read the full recovery data */
1149 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1150 rec.data_len, 0) == -1) {
1151 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1152 tdb->ecode = TDB_ERR_IO;
1156 /* recover the file data */
1158 while (p+8 < data + rec.data_len) {
1164 memcpy(&len, p+4, 4);
1166 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1168 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1169 tdb->ecode = TDB_ERR_IO;
1177 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1178 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1179 tdb->ecode = TDB_ERR_IO;
1183 /* if the recovery area is after the recovered eof then remove it */
1184 if (recovery_eof <= recovery_head) {
1185 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1186 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1187 tdb->ecode = TDB_ERR_IO;
1192 /* remove the recovery magic */
1193 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
1195 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1196 tdb->ecode = TDB_ERR_IO;
1200 /* reduce the file size to the old size */
1202 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1203 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1204 tdb->ecode = TDB_ERR_IO;
1207 tdb->map_size = recovery_eof;
1210 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1211 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1212 tdb->ecode = TDB_ERR_IO;
1216 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",