2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 2005
7 Copyright (C) Rusty Russell 2010
9 ** NOTE! The following LGPL license applies to the tdb
10 ** library. This does NOT imply that all of Samba is released
13 This library is free software; you can redistribute it and/or
14 modify it under the terms of the GNU Lesser General Public
15 License as published by the Free Software Foundation; either
16 version 3 of the License, or (at your option) any later version.
18 This library is distributed in the hope that it will be useful,
19 but WITHOUT ANY WARRANTY; without even the implied warranty of
20 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 Lesser General Public License for more details.
23 You should have received a copy of the GNU Lesser General Public
24 License along with this library; if not, see <http://www.gnu.org/licenses/>.
28 #define SAFE_FREE(x) do { if ((x) != NULL) {free(x); (x)=NULL;} } while(0)
33 - only allow a single transaction at a time per database. This makes
34 using the transaction API simpler, as otherwise the caller would
35 have to cope with temporary failures in transactions that conflict
36 with other current transactions
38 - keep the transaction recovery information in the same file as the
39 database, using a special 'transaction recovery' record pointed at
40 by the header. This removes the need for extra journal files as
41 used by some other databases
43 - dynamically allocated the transaction recover record, re-using it
44 for subsequent transactions. If a larger record is needed then
45 tdb_free() the old record to place it on the normal tdb freelist
46 before allocating the new record
48 - during transactions, keep a linked list of writes all that have
49 been performed by intercepting all tdb_write() calls. The hooked
50 transaction versions of tdb_read() and tdb_write() check this
51 linked list and try to use the elements of the list in preference
54 - don't allow any locks to be held when a transaction starts,
55 otherwise we can end up with deadlock (plus lack of lock nesting
56 in posix locks would mean the lock is lost)
58 - if the caller gains a lock during the transaction but doesn't
59 release it then fail the commit
61 - allow for nested calls to tdb_transaction_start(), re-using the
62 existing transaction record. If the inner transaction is cancelled
63 then a subsequent commit will fail
65 - keep a mirrored copy of the tdb hash chain heads to allow for the
66 fast hash heads scan on traverse, updating the mirrored copy in
67 the transaction version of tdb_write
69 - allow callers to mix transaction and non-transaction use of tdb,
70 although once a transaction is started then an exclusive lock is
71 gained until the transaction is committed or cancelled
73 - the commit stategy involves first saving away all modified data
74 into a linearised buffer in the transaction recovery area, then
75 marking the transaction recovery area with a magic value to
76 indicate a valid recovery record. In total 4 fsync/msync calls are
77 needed per commit to prevent race conditions. It might be possible
78 to reduce this to 3 or even 2 with some more work.
80 - check for a valid recovery record on open of the tdb, while the
81 open lock is held. Automatically recover from the transaction
82 recovery area if needed, then continue with the open as
83 usual. This allows for smooth crash recovery with no administrator
86 - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
87 still available, but no transaction recovery area is used and no
88 fsync/msync calls are made.
93 hold the context of any current transaction
95 struct tdb_transaction {
96 /* the original io methods - used to do IOs to the real db */
97 const struct tdb_methods *io_methods;
99 /* the list of transaction blocks. When a block is first
100 written to, it gets created in this list */
103 size_t last_block_size; /* number of valid bytes in the last block */
105 /* non-zero when an internal transaction error has
106 occurred. All write operations will then fail until the
107 transaction is ended */
108 int transaction_error;
110 /* when inside a transaction we need to keep track of any
111 nested tdb_transaction_start() calls, as these are allowed,
112 but don't create a new transaction */
115 /* set when a prepare has already occurred */
117 tdb_off_t magic_offset;
119 /* old file size before transaction */
120 tdb_len_t old_map_size;
125 read while in a transaction. We need to check first if the data is in our list
126 of transaction elements, then if not do a real read
128 static enum TDB_ERROR transaction_read(struct tdb_context *tdb, tdb_off_t off,
129 void *buf, tdb_len_t len)
132 enum TDB_ERROR ecode;
134 /* break it down into block sized ops */
135 while (len + (off % getpagesize()) > getpagesize()) {
136 tdb_len_t len2 = getpagesize() - (off % getpagesize());
137 ecode = transaction_read(tdb, off, buf, len2);
138 if (ecode != TDB_SUCCESS) {
143 buf = (void *)(len2 + (char *)buf);
150 blk = off / getpagesize();
152 /* see if we have it in the block list */
153 if (tdb->transaction->num_blocks <= blk ||
154 tdb->transaction->blocks[blk] == NULL) {
155 /* nope, do a real read */
156 ecode = tdb->transaction->io_methods->tread(tdb, off, buf, len);
157 if (ecode != TDB_SUCCESS) {
163 /* it is in the block list. Now check for the last block */
164 if (blk == tdb->transaction->num_blocks-1) {
165 if (len > tdb->transaction->last_block_size) {
171 /* now copy it out of this block */
172 memcpy(buf, tdb->transaction->blocks[blk] + (off % getpagesize()), len);
176 tdb->transaction->transaction_error = 1;
177 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
178 "transaction_read: failed at off=%zu len=%zu",
179 (size_t)off, (size_t)len);
184 write while in a transaction
186 static enum TDB_ERROR transaction_write(struct tdb_context *tdb, tdb_off_t off,
187 const void *buf, tdb_len_t len)
190 enum TDB_ERROR ecode;
192 /* Only a commit is allowed on a prepared transaction */
193 if (tdb->transaction->prepared) {
194 ecode = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_ERROR,
195 "transaction_write: transaction already"
196 " prepared, write not allowed");
200 /* break it up into block sized chunks */
201 while (len + (off % getpagesize()) > getpagesize()) {
202 tdb_len_t len2 = getpagesize() - (off % getpagesize());
203 ecode = transaction_write(tdb, off, buf, len2);
204 if (ecode != TDB_SUCCESS) {
210 buf = (const void *)(len2 + (const char *)buf);
218 blk = off / getpagesize();
219 off = off % getpagesize();
221 if (tdb->transaction->num_blocks <= blk) {
222 uint8_t **new_blocks;
223 /* expand the blocks array */
224 if (tdb->transaction->blocks == NULL) {
225 new_blocks = (uint8_t **)malloc(
226 (blk+1)*sizeof(uint8_t *));
228 new_blocks = (uint8_t **)realloc(
229 tdb->transaction->blocks,
230 (blk+1)*sizeof(uint8_t *));
232 if (new_blocks == NULL) {
233 ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
235 " failed to allocate");
238 memset(&new_blocks[tdb->transaction->num_blocks], 0,
239 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
240 tdb->transaction->blocks = new_blocks;
241 tdb->transaction->num_blocks = blk+1;
242 tdb->transaction->last_block_size = 0;
245 /* allocate and fill a block? */
246 if (tdb->transaction->blocks[blk] == NULL) {
247 tdb->transaction->blocks[blk] = (uint8_t *)calloc(getpagesize(), 1);
248 if (tdb->transaction->blocks[blk] == NULL) {
249 ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
251 " failed to allocate");
254 if (tdb->transaction->old_map_size > blk * getpagesize()) {
255 tdb_len_t len2 = getpagesize();
256 if (len2 + (blk * getpagesize()) > tdb->transaction->old_map_size) {
257 len2 = tdb->transaction->old_map_size - (blk * getpagesize());
259 ecode = tdb->transaction->io_methods->tread(tdb,
261 tdb->transaction->blocks[blk],
263 if (ecode != TDB_SUCCESS) {
264 ecode = tdb_logerr(tdb, ecode,
268 " read old block: %s",
270 SAFE_FREE(tdb->transaction->blocks[blk]);
273 if (blk == tdb->transaction->num_blocks-1) {
274 tdb->transaction->last_block_size = len2;
279 /* overwrite part of an existing block */
281 memset(tdb->transaction->blocks[blk] + off, 0, len);
283 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
285 if (blk == tdb->transaction->num_blocks-1) {
286 if (len + off > tdb->transaction->last_block_size) {
287 tdb->transaction->last_block_size = len + off;
294 tdb->transaction->transaction_error = 1;
300 write while in a transaction - this varient never expands the transaction blocks, it only
301 updates existing blocks. This means it cannot change the recovery size
303 static void transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
304 const void *buf, tdb_len_t len)
308 /* break it up into block sized chunks */
309 while (len + (off % getpagesize()) > getpagesize()) {
310 tdb_len_t len2 = getpagesize() - (off % getpagesize());
311 transaction_write_existing(tdb, off, buf, len2);
315 buf = (const void *)(len2 + (const char *)buf);
323 blk = off / getpagesize();
324 off = off % getpagesize();
326 if (tdb->transaction->num_blocks <= blk ||
327 tdb->transaction->blocks[blk] == NULL) {
331 if (blk == tdb->transaction->num_blocks-1 &&
332 off + len > tdb->transaction->last_block_size) {
333 if (off >= tdb->transaction->last_block_size) {
336 len = tdb->transaction->last_block_size - off;
339 /* overwrite part of an existing block */
340 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
345 out of bounds check during a transaction
347 static enum TDB_ERROR transaction_oob(struct tdb_context *tdb, tdb_off_t len,
350 if (len <= tdb->map_size) {
354 tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
355 "tdb_oob len %lld beyond transaction size %lld",
357 (long long)tdb->map_size);
363 transaction version of tdb_expand().
365 static enum TDB_ERROR transaction_expand_file(struct tdb_context *tdb,
368 enum TDB_ERROR ecode;
370 /* add a write to the transaction elements, so subsequent
371 reads see the zero data */
372 ecode = transaction_write(tdb, tdb->map_size, NULL, addition);
373 if (ecode == TDB_SUCCESS) {
374 tdb->map_size += addition;
379 static void *transaction_direct(struct tdb_context *tdb, tdb_off_t off,
380 size_t len, bool write_mode)
382 size_t blk = off / getpagesize(), end_blk;
384 /* This is wrong for zero-length blocks, but will fail gracefully */
385 end_blk = (off + len - 1) / getpagesize();
387 /* Can only do direct if in single block and we've already copied. */
391 if (blk >= tdb->transaction->num_blocks)
393 if (tdb->transaction->blocks[blk] == NULL)
395 return tdb->transaction->blocks[blk] + off % getpagesize();
398 /* Single which we have copied? */
400 && blk < tdb->transaction->num_blocks
401 && tdb->transaction->blocks[blk])
402 return tdb->transaction->blocks[blk] + off % getpagesize();
404 /* Otherwise must be all not copied. */
405 while (blk < end_blk) {
406 if (blk >= tdb->transaction->num_blocks)
408 if (tdb->transaction->blocks[blk])
412 return tdb->transaction->io_methods->direct(tdb, off, len, false);
415 static const struct tdb_methods transaction_methods = {
419 transaction_expand_file,
426 static enum TDB_ERROR transaction_sync(struct tdb_context *tdb,
427 tdb_off_t offset, tdb_len_t length)
429 if (tdb->flags & TDB_NOSYNC) {
433 if (fsync(tdb->fd) != 0) {
434 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
435 "tdb_transaction: fsync failed: %s",
440 tdb_off_t moffset = offset & ~(getpagesize()-1);
441 if (msync(moffset + (char *)tdb->map_ptr,
442 length + (offset - moffset), MS_SYNC) != 0) {
443 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
444 "tdb_transaction: msync failed: %s",
453 static void _tdb_transaction_cancel(struct tdb_context *tdb)
456 enum TDB_ERROR ecode;
458 if (tdb->transaction == NULL) {
459 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
460 "tdb_transaction_cancel: no transaction");
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;
482 uint64_t invalid = TDB_RECOVERY_INVALID_MAGIC;
484 /* remove the recovery marker */
485 ecode = methods->twrite(tdb, tdb->transaction->magic_offset,
486 &invalid, sizeof(invalid));
487 if (ecode == TDB_SUCCESS)
488 ecode = transaction_sync(tdb,
489 tdb->transaction->magic_offset,
491 if (ecode != TDB_SUCCESS) {
492 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
493 "tdb_transaction_cancel: failed to remove"
498 if (tdb->allrecord_lock.count)
499 tdb_allrecord_unlock(tdb, tdb->allrecord_lock.ltype);
501 /* restore the normal io methods */
502 tdb->methods = tdb->transaction->io_methods;
504 tdb_transaction_unlock(tdb, F_WRLCK);
506 if (tdb_has_open_lock(tdb))
507 tdb_unlock_open(tdb);
509 SAFE_FREE(tdb->transaction);
513 start a tdb transaction. No token is returned, as only a single
514 transaction is allowed to be pending per tdb_context
516 enum TDB_ERROR tdb_transaction_start(struct tdb_context *tdb)
518 enum TDB_ERROR ecode;
520 /* some sanity checks */
521 if (tdb->read_only || (tdb->flags & TDB_INTERNAL)) {
522 return tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
523 "tdb_transaction_start: cannot start a"
524 " transaction on a read-only or internal db");
527 /* cope with nested tdb_transaction_start() calls */
528 if (tdb->transaction != NULL) {
529 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_USE_ERROR,
530 "tdb_transaction_start:"
531 " already inside transaction");
534 if (tdb_has_hash_locks(tdb)) {
535 /* the caller must not have any locks when starting a
536 transaction as otherwise we'll be screwed by lack
537 of nested locks in posix */
538 return tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
539 "tdb_transaction_start: cannot start a"
540 " transaction with locks held");
543 tdb->transaction = (struct tdb_transaction *)
544 calloc(sizeof(struct tdb_transaction), 1);
545 if (tdb->transaction == NULL) {
546 return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
547 "tdb_transaction_start: cannot allocate");
550 /* get the transaction write lock. This is a blocking lock. As
551 discussed with Volker, there are a number of ways we could
552 make this async, which we will probably do in the future */
553 ecode = tdb_transaction_lock(tdb, F_WRLCK);
554 if (ecode != TDB_SUCCESS) {
555 SAFE_FREE(tdb->transaction->blocks);
556 SAFE_FREE(tdb->transaction);
560 /* get a read lock over entire file. This is upgraded to a write
561 lock during the commit */
562 ecode = tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true);
563 if (ecode != TDB_SUCCESS) {
564 goto fail_allrecord_lock;
567 /* make sure we know about any file expansions already done by
569 tdb->methods->oob(tdb, tdb->map_size + 1, true);
570 tdb->transaction->old_map_size = tdb->map_size;
572 /* finally hook the io methods, replacing them with
573 transaction specific methods */
574 tdb->transaction->io_methods = tdb->methods;
575 tdb->methods = &transaction_methods;
579 tdb_transaction_unlock(tdb, F_WRLCK);
580 SAFE_FREE(tdb->transaction->blocks);
581 SAFE_FREE(tdb->transaction);
587 cancel the current transaction
589 void tdb_transaction_cancel(struct tdb_context *tdb)
591 _tdb_transaction_cancel(tdb);
595 work out how much space the linearised recovery data will consume
597 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
599 tdb_len_t recovery_size = 0;
602 recovery_size = sizeof(tdb_len_t);
603 for (i=0;i<tdb->transaction->num_blocks;i++) {
604 if (i * getpagesize() >= tdb->transaction->old_map_size) {
607 if (tdb->transaction->blocks[i] == NULL) {
610 recovery_size += 2*sizeof(tdb_off_t);
611 if (i == tdb->transaction->num_blocks-1) {
612 recovery_size += tdb->transaction->last_block_size;
614 recovery_size += getpagesize();
618 return recovery_size;
622 allocate the recovery area, or use an existing recovery area if it is
625 static enum TDB_ERROR tdb_recovery_allocate(struct tdb_context *tdb,
626 tdb_len_t *recovery_size,
627 tdb_off_t *recovery_offset,
628 tdb_len_t *recovery_max_size)
630 struct tdb_recovery_record rec;
631 const struct tdb_methods *methods = tdb->transaction->io_methods;
632 tdb_off_t recovery_head;
634 enum TDB_ERROR ecode;
636 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
637 if (TDB_OFF_IS_ERR(recovery_head)) {
638 return tdb_logerr(tdb, recovery_head, TDB_LOG_ERROR,
639 "tdb_recovery_allocate:"
640 " failed to read recovery head");
643 if (recovery_head != 0) {
644 ecode = methods->tread(tdb, recovery_head, &rec, sizeof(rec));
645 if (ecode != TDB_SUCCESS) {
646 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
647 "tdb_recovery_allocate:"
648 " failed to read recovery record");
650 tdb_convert(tdb, &rec, sizeof(rec));
651 /* ignore invalid recovery regions: can happen in crash */
652 if (rec.magic != TDB_RECOVERY_MAGIC &&
653 rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
658 *recovery_size = tdb_recovery_size(tdb);
660 if (recovery_head != 0 && *recovery_size <= rec.max_len) {
661 /* it fits in the existing area */
662 *recovery_max_size = rec.max_len;
663 *recovery_offset = recovery_head;
667 /* we need to free up the old recovery area, then allocate a
668 new one at the end of the file. Note that we cannot use
669 normal allocation to allocate the new one as that might return
670 us an area that is being currently used (as of the start of
672 if (recovery_head != 0) {
673 add_stat(tdb, frees, 1);
674 ecode = add_free_record(tdb, recovery_head,
675 sizeof(rec) + rec.max_len);
676 if (ecode != TDB_SUCCESS) {
677 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
678 "tdb_recovery_allocate:"
679 " failed to free previous"
684 /* the tdb_free() call might have increased the recovery size */
685 *recovery_size = tdb_recovery_size(tdb);
687 /* round up to a multiple of page size */
689 = (((sizeof(rec) + *recovery_size) + getpagesize()-1)
690 & ~(getpagesize()-1))
692 *recovery_offset = tdb->map_size;
693 recovery_head = *recovery_offset;
695 /* Restore ->map_size before calling underlying expand_file.
696 Also so that we don't try to expand the file again in the
697 transaction commit, which would destroy the recovery
699 addition = (tdb->map_size - tdb->transaction->old_map_size) +
700 sizeof(rec) + *recovery_max_size;
701 tdb->map_size = tdb->transaction->old_map_size;
702 ecode = methods->expand_file(tdb, addition);
703 if (ecode != TDB_SUCCESS) {
704 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
705 "tdb_recovery_allocate:"
706 " failed to create recovery area");
709 /* we have to reset the old map size so that we don't try to
710 expand the file again in the transaction commit, which
711 would destroy the recovery area */
712 tdb->transaction->old_map_size = tdb->map_size;
714 /* write the recovery header offset and sync - we can sync without a race here
715 as the magic ptr in the recovery record has not been set */
716 tdb_convert(tdb, &recovery_head, sizeof(recovery_head));
717 ecode = methods->twrite(tdb, offsetof(struct tdb_header, recovery),
718 &recovery_head, sizeof(tdb_off_t));
719 if (ecode != TDB_SUCCESS) {
720 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
721 "tdb_recovery_allocate:"
722 " failed to write recovery head");
724 transaction_write_existing(tdb, offsetof(struct tdb_header, recovery),
730 /* Set up header for the recovery record. */
731 static void set_recovery_header(struct tdb_recovery_record *rec,
733 uint64_t datalen, uint64_t actuallen,
737 rec->max_len = actuallen;
743 setup the recovery data that will be used on a crash during commit
745 static enum TDB_ERROR transaction_setup_recovery(struct tdb_context *tdb,
746 tdb_off_t *magic_offset)
748 tdb_len_t recovery_size;
749 unsigned char *data, *p;
750 const struct tdb_methods *methods = tdb->transaction->io_methods;
751 struct tdb_recovery_record *rec;
752 tdb_off_t recovery_offset, recovery_max_size;
753 tdb_off_t old_map_size = tdb->transaction->old_map_size;
754 uint64_t magic, tailer;
756 enum TDB_ERROR ecode;
759 check that the recovery area has enough space
761 ecode = tdb_recovery_allocate(tdb, &recovery_size,
762 &recovery_offset, &recovery_max_size);
763 if (ecode != TDB_SUCCESS) {
767 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
769 return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
770 "transaction_setup_recovery:"
774 rec = (struct tdb_recovery_record *)data;
775 set_recovery_header(rec, TDB_RECOVERY_INVALID_MAGIC,
776 recovery_size, recovery_max_size, old_map_size);
777 tdb_convert(tdb, rec, sizeof(*rec));
779 /* build the recovery data into a single blob to allow us to do a single
780 large write, which should be more efficient */
781 p = data + sizeof(*rec);
782 for (i=0;i<tdb->transaction->num_blocks;i++) {
786 if (tdb->transaction->blocks[i] == NULL) {
790 offset = i * getpagesize();
791 length = getpagesize();
792 if (i == tdb->transaction->num_blocks-1) {
793 length = tdb->transaction->last_block_size;
796 if (offset >= old_map_size) {
799 if (offset + length > tdb->map_size) {
801 return tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
802 "tdb_transaction_setup_recovery:"
803 " transaction data over new region"
806 memcpy(p, &offset, sizeof(offset));
807 memcpy(p + sizeof(offset), &length, sizeof(length));
808 tdb_convert(tdb, p, sizeof(offset) + sizeof(length));
810 /* the recovery area contains the old data, not the
811 new data, so we have to call the original tdb_read
813 ecode = methods->tread(tdb, offset,
814 p + sizeof(offset) + sizeof(length),
816 if (ecode != TDB_SUCCESS) {
820 p += sizeof(offset) + sizeof(length) + length;
824 tailer = sizeof(*rec) + recovery_max_size;
825 memcpy(p, &tailer, sizeof(tailer));
826 tdb_convert(tdb, p, sizeof(tailer));
828 /* write the recovery data to the recovery area */
829 ecode = methods->twrite(tdb, recovery_offset, data,
830 sizeof(*rec) + recovery_size);
831 if (ecode != TDB_SUCCESS) {
833 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
834 "tdb_transaction_setup_recovery:"
835 " failed to write recovery data");
837 transaction_write_existing(tdb, recovery_offset, data,
838 sizeof(*rec) + recovery_size);
840 /* as we don't have ordered writes, we have to sync the recovery
841 data before we update the magic to indicate that the recovery
843 ecode = transaction_sync(tdb, recovery_offset,
844 sizeof(*rec) + recovery_size);
845 if (ecode != TDB_SUCCESS) {
852 magic = TDB_RECOVERY_MAGIC;
853 tdb_convert(tdb, &magic, sizeof(magic));
855 *magic_offset = recovery_offset + offsetof(struct tdb_recovery_record,
858 ecode = methods->twrite(tdb, *magic_offset, &magic, sizeof(magic));
859 if (ecode != TDB_SUCCESS) {
860 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
861 "tdb_transaction_setup_recovery:"
862 " failed to write recovery magic");
864 transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic));
866 /* ensure the recovery magic marker is on disk */
867 return transaction_sync(tdb, *magic_offset, sizeof(magic));
870 static enum TDB_ERROR _tdb_transaction_prepare_commit(struct tdb_context *tdb)
872 const struct tdb_methods *methods;
873 enum TDB_ERROR ecode;
875 if (tdb->transaction == NULL) {
876 return tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
877 "tdb_transaction_prepare_commit:"
881 if (tdb->transaction->prepared) {
882 _tdb_transaction_cancel(tdb);
883 return tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
884 "tdb_transaction_prepare_commit:"
885 " transaction already prepared");
888 if (tdb->transaction->transaction_error) {
889 _tdb_transaction_cancel(tdb);
890 return tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_ERROR,
891 "tdb_transaction_prepare_commit:"
892 " transaction error pending");
896 if (tdb->transaction->nesting != 0) {
897 tdb->transaction->nesting--;
901 /* check for a null transaction */
902 if (tdb->transaction->blocks == NULL) {
906 methods = tdb->transaction->io_methods;
908 /* upgrade the main transaction lock region to a write lock */
909 ecode = tdb_allrecord_upgrade(tdb);
910 if (ecode != TDB_SUCCESS) {
911 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
912 "tdb_transaction_prepare_commit:"
913 " failed to upgrade hash locks");
914 _tdb_transaction_cancel(tdb);
918 /* get the open lock - this prevents new users attaching to the database
920 ecode = tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK);
921 if (ecode != TDB_SUCCESS) {
922 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
923 "tdb_transaction_prepare_commit:"
924 " failed to get open lock");
925 _tdb_transaction_cancel(tdb);
929 /* Since we have whole db locked, we don't need the expansion lock. */
930 if (!(tdb->flags & TDB_NOSYNC)) {
931 /* write the recovery data to the end of the file */
932 ecode = transaction_setup_recovery(tdb,
935 if (ecode != TDB_SUCCESS) {
936 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
937 "tdb_transaction_prepare_commit:"
938 " failed to setup recovery data");
939 _tdb_transaction_cancel(tdb);
944 tdb->transaction->prepared = true;
946 /* expand the file to the new size if needed */
947 if (tdb->map_size != tdb->transaction->old_map_size) {
948 tdb_len_t add = tdb->map_size - tdb->transaction->old_map_size;
949 /* Restore original map size for tdb_expand_file */
950 tdb->map_size = tdb->transaction->old_map_size;
951 ecode = methods->expand_file(tdb, add);
952 if (ecode != TDB_SUCCESS) {
953 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
954 "tdb_transaction_prepare_commit:"
955 " expansion failed");
956 _tdb_transaction_cancel(tdb);
961 /* Keep the open lock until the actual commit */
966 prepare to commit the current transaction
968 enum TDB_ERROR tdb_transaction_prepare_commit(struct tdb_context *tdb)
970 return _tdb_transaction_prepare_commit(tdb);
974 commit the current transaction
976 enum TDB_ERROR tdb_transaction_commit(struct tdb_context *tdb)
978 const struct tdb_methods *methods;
980 enum TDB_ERROR ecode;
982 if (tdb->transaction == NULL) {
983 return tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
984 "tdb_transaction_commit: no transaction");
987 tdb_trace(tdb, "tdb_transaction_commit");
989 if (tdb->transaction->nesting != 0) {
990 tdb->transaction->nesting--;
994 /* check for a null transaction */
995 if (tdb->transaction->blocks == NULL) {
996 _tdb_transaction_cancel(tdb);
1000 if (!tdb->transaction->prepared) {
1001 ecode = _tdb_transaction_prepare_commit(tdb);
1002 if (ecode != TDB_SUCCESS)
1006 methods = tdb->transaction->io_methods;
1008 /* perform all the writes */
1009 for (i=0;i<tdb->transaction->num_blocks;i++) {
1013 if (tdb->transaction->blocks[i] == NULL) {
1017 offset = i * getpagesize();
1018 length = getpagesize();
1019 if (i == tdb->transaction->num_blocks-1) {
1020 length = tdb->transaction->last_block_size;
1023 ecode = methods->twrite(tdb, offset,
1024 tdb->transaction->blocks[i], length);
1025 if (ecode != TDB_SUCCESS) {
1026 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1027 "tdb_transaction_commit:"
1028 " write failed during commit");
1030 /* we've overwritten part of the data and
1031 possibly expanded the file, so we need to
1032 run the crash recovery code */
1033 tdb->methods = methods;
1034 tdb_transaction_recover(tdb);
1036 _tdb_transaction_cancel(tdb);
1040 SAFE_FREE(tdb->transaction->blocks[i]);
1043 SAFE_FREE(tdb->transaction->blocks);
1044 tdb->transaction->num_blocks = 0;
1046 /* ensure the new data is on disk */
1047 ecode = transaction_sync(tdb, 0, tdb->map_size);
1048 if (ecode != TDB_SUCCESS) {
1053 TODO: maybe write to some dummy hdr field, or write to magic
1054 offset without mmap, before the last sync, instead of the
1058 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1059 don't change the mtime of the file, this means the file may
1060 not be backed up (as tdb rounding to block sizes means that
1061 file size changes are quite rare too). The following forces
1062 mtime changes when a transaction completes */
1064 utime(tdb->name, NULL);
1067 /* use a transaction cancel to free memory and remove the
1068 transaction locks */
1069 _tdb_transaction_cancel(tdb);
1076 recover from an aborted transaction. Must be called with exclusive
1077 database write access already established (including the open
1078 lock to prevent new processes attaching)
1080 enum TDB_ERROR tdb_transaction_recover(struct tdb_context *tdb)
1082 tdb_off_t recovery_head, recovery_eof;
1083 unsigned char *data, *p;
1084 struct tdb_recovery_record rec;
1085 enum TDB_ERROR ecode;
1087 /* find the recovery area */
1088 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
1089 if (TDB_OFF_IS_ERR(recovery_head)) {
1090 return tdb_logerr(tdb, recovery_head, TDB_LOG_ERROR,
1091 "tdb_transaction_recover:"
1092 " failed to read recovery head");
1095 if (recovery_head == 0) {
1096 /* we have never allocated a recovery record */
1100 /* read the recovery record */
1101 ecode = tdb_read_convert(tdb, recovery_head, &rec, sizeof(rec));
1102 if (ecode != TDB_SUCCESS) {
1103 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1104 "tdb_transaction_recover:"
1105 " failed to read recovery record");
1108 if (rec.magic != TDB_RECOVERY_MAGIC) {
1109 /* there is no valid recovery data */
1113 if (tdb->read_only) {
1114 return tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
1115 "tdb_transaction_recover:"
1116 " attempt to recover read only database");
1119 recovery_eof = rec.eof;
1121 data = (unsigned char *)malloc(rec.len);
1123 return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
1124 "tdb_transaction_recover:"
1125 " failed to allocate recovery data");
1128 /* read the full recovery data */
1129 ecode = tdb->methods->tread(tdb, recovery_head + sizeof(rec), data,
1131 if (ecode != TDB_SUCCESS) {
1132 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1133 "tdb_transaction_recover:"
1134 " failed to read recovery data");
1137 /* recover the file data */
1139 while (p+sizeof(tdb_off_t)+sizeof(tdb_len_t) < data + rec.len) {
1142 tdb_convert(tdb, p, sizeof(ofs) + sizeof(len));
1143 memcpy(&ofs, p, sizeof(ofs));
1144 memcpy(&len, p + sizeof(ofs), sizeof(len));
1145 p += sizeof(ofs) + sizeof(len);
1147 ecode = tdb->methods->twrite(tdb, ofs, p, len);
1148 if (ecode != TDB_SUCCESS) {
1150 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1151 "tdb_transaction_recover:"
1152 " failed to recover %zu bytes"
1154 (size_t)len, (size_t)ofs);
1161 ecode = transaction_sync(tdb, 0, tdb->map_size);
1162 if (ecode != TDB_SUCCESS) {
1163 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1164 "tdb_transaction_recover:"
1165 " failed to sync recovery");
1168 /* if the recovery area is after the recovered eof then remove it */
1169 if (recovery_eof <= recovery_head) {
1170 ecode = tdb_write_off(tdb, offsetof(struct tdb_header,
1173 if (ecode != TDB_SUCCESS) {
1174 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1175 "tdb_transaction_recover:"
1176 " failed to remove recovery head");
1180 /* remove the recovery magic */
1181 ecode = tdb_write_off(tdb,
1183 + offsetof(struct tdb_recovery_record, magic),
1184 TDB_RECOVERY_INVALID_MAGIC);
1185 if (ecode != TDB_SUCCESS) {
1186 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1187 "tdb_transaction_recover:"
1188 " failed to remove recovery magic");
1191 ecode = transaction_sync(tdb, 0, recovery_eof);
1192 if (ecode != TDB_SUCCESS) {
1193 return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1194 "tdb_transaction_recover:"
1195 " failed to sync2 recovery");
1198 tdb_logerr(tdb, TDB_SUCCESS, TDB_LOG_WARNING,
1199 "tdb_transaction_recover: recovered %zu byte database",
1200 (size_t)recovery_eof);
1206 tdb_bool_err tdb_needs_recovery(struct tdb_context *tdb)
1208 tdb_off_t recovery_head;
1209 struct tdb_recovery_record rec;
1210 enum TDB_ERROR ecode;
1212 /* find the recovery area */
1213 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
1214 if (TDB_OFF_IS_ERR(recovery_head)) {
1215 return recovery_head;
1218 if (recovery_head == 0) {
1219 /* we have never allocated a recovery record */
1223 /* read the recovery record */
1224 ecode = tdb_read_convert(tdb, recovery_head, &rec, sizeof(rec));
1225 if (ecode != TDB_SUCCESS) {
1229 return (rec.magic == TDB_RECOVERY_MAGIC);