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) {
377 tdb->map_size += addition;
381 static void *transaction_direct(struct tdb_context *tdb, tdb_off_t off,
382 size_t len, bool write_mode)
384 size_t blk = off / getpagesize(), end_blk;
386 /* This is wrong for zero-length blocks, but will fail gracefully */
387 end_blk = (off + len - 1) / getpagesize();
389 /* Can only do direct if in single block and we've already copied. */
393 if (blk >= tdb->transaction->num_blocks)
395 if (tdb->transaction->blocks[blk] == NULL)
397 return tdb->transaction->blocks[blk] + off % getpagesize();
400 /* Single which we have copied? */
402 && blk < tdb->transaction->num_blocks
403 && tdb->transaction->blocks[blk])
404 return tdb->transaction->blocks[blk] + off % getpagesize();
406 /* Otherwise must be all not copied. */
407 while (blk < end_blk) {
408 if (blk >= tdb->transaction->num_blocks)
410 if (tdb->transaction->blocks[blk])
414 return tdb->transaction->io_methods->direct(tdb, off, len, false);
417 static const struct tdb_methods transaction_methods = {
421 transaction_expand_file,
428 static enum TDB_ERROR transaction_sync(struct tdb_context *tdb,
429 tdb_off_t offset, tdb_len_t length)
431 if (tdb->flags & TDB_NOSYNC) {
435 if (fsync(tdb->fd) != 0) {
436 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
437 "tdb_transaction: fsync failed: %s",
442 tdb_off_t moffset = offset & ~(getpagesize()-1);
443 if (msync(moffset + (char *)tdb->map_ptr,
444 length + (offset - moffset), MS_SYNC) != 0) {
445 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
446 "tdb_transaction: msync failed: %s",
455 static void _tdb_transaction_cancel(struct tdb_context *tdb)
458 enum TDB_ERROR ecode;
460 if (tdb->transaction == NULL) {
461 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
462 "tdb_transaction_cancel: no transaction");
466 if (tdb->transaction->nesting != 0) {
467 tdb->transaction->transaction_error = 1;
468 tdb->transaction->nesting--;
472 tdb->map_size = tdb->transaction->old_map_size;
474 /* free all the transaction blocks */
475 for (i=0;i<tdb->transaction->num_blocks;i++) {
476 if (tdb->transaction->blocks[i] != NULL) {
477 free(tdb->transaction->blocks[i]);
480 SAFE_FREE(tdb->transaction->blocks);
482 if (tdb->transaction->magic_offset) {
483 const struct tdb_methods *methods = tdb->transaction->io_methods;
484 uint64_t invalid = TDB_RECOVERY_INVALID_MAGIC;
486 /* remove the recovery marker */
487 ecode = methods->twrite(tdb, tdb->transaction->magic_offset,
488 &invalid, sizeof(invalid));
489 if (ecode == TDB_SUCCESS)
490 ecode = transaction_sync(tdb,
491 tdb->transaction->magic_offset,
493 if (ecode != TDB_SUCCESS) {
494 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
495 "tdb_transaction_cancel: failed to remove"
500 if (tdb->allrecord_lock.count)
501 tdb_allrecord_unlock(tdb, tdb->allrecord_lock.ltype);
503 /* restore the normal io methods */
504 tdb->methods = tdb->transaction->io_methods;
506 tdb_transaction_unlock(tdb, F_WRLCK);
508 if (tdb_has_open_lock(tdb))
509 tdb_unlock_open(tdb);
511 SAFE_FREE(tdb->transaction);
515 start a tdb transaction. No token is returned, as only a single
516 transaction is allowed to be pending per tdb_context
518 int tdb_transaction_start(struct tdb_context *tdb)
520 enum TDB_ERROR ecode;
522 /* some sanity checks */
523 if (tdb->read_only || (tdb->flags & TDB_INTERNAL)) {
524 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
525 "tdb_transaction_start: cannot start a transaction"
526 " on a read-only or internal db");
530 /* cope with nested tdb_transaction_start() calls */
531 if (tdb->transaction != NULL) {
532 tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_USE_ERROR,
533 "tdb_transaction_start:"
534 " already inside transaction");
538 if (tdb_has_hash_locks(tdb)) {
539 /* the caller must not have any locks when starting a
540 transaction as otherwise we'll be screwed by lack
541 of nested locks in posix */
542 tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
543 "tdb_transaction_start: cannot start a transaction"
548 tdb->transaction = (struct tdb_transaction *)
549 calloc(sizeof(struct tdb_transaction), 1);
550 if (tdb->transaction == NULL) {
551 tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
552 "tdb_transaction_start: cannot allocate");
556 /* get the transaction write lock. This is a blocking lock. As
557 discussed with Volker, there are a number of ways we could
558 make this async, which we will probably do in the future */
559 ecode = tdb_transaction_lock(tdb, F_WRLCK);
560 if (ecode != TDB_SUCCESS) {
562 SAFE_FREE(tdb->transaction->blocks);
563 SAFE_FREE(tdb->transaction);
567 /* get a read lock over entire file. This is upgraded to a write
568 lock during the commit */
569 ecode = tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true);
570 if (ecode != TDB_SUCCESS) {
572 goto fail_allrecord_lock;
575 /* make sure we know about any file expansions already done by
577 tdb->methods->oob(tdb, tdb->map_size + 1, true);
578 tdb->transaction->old_map_size = tdb->map_size;
580 /* finally hook the io methods, replacing them with
581 transaction specific methods */
582 tdb->transaction->io_methods = tdb->methods;
583 tdb->methods = &transaction_methods;
587 tdb_transaction_unlock(tdb, F_WRLCK);
588 SAFE_FREE(tdb->transaction->blocks);
589 SAFE_FREE(tdb->transaction);
595 cancel the current transaction
597 void tdb_transaction_cancel(struct tdb_context *tdb)
599 _tdb_transaction_cancel(tdb);
603 work out how much space the linearised recovery data will consume
605 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
607 tdb_len_t recovery_size = 0;
610 recovery_size = sizeof(tdb_len_t);
611 for (i=0;i<tdb->transaction->num_blocks;i++) {
612 if (i * getpagesize() >= tdb->transaction->old_map_size) {
615 if (tdb->transaction->blocks[i] == NULL) {
618 recovery_size += 2*sizeof(tdb_off_t);
619 if (i == tdb->transaction->num_blocks-1) {
620 recovery_size += tdb->transaction->last_block_size;
622 recovery_size += getpagesize();
626 return recovery_size;
630 allocate the recovery area, or use an existing recovery area if it is
633 static int tdb_recovery_allocate(struct tdb_context *tdb,
634 tdb_len_t *recovery_size,
635 tdb_off_t *recovery_offset,
636 tdb_len_t *recovery_max_size)
638 struct tdb_recovery_record rec;
639 const struct tdb_methods *methods = tdb->transaction->io_methods;
640 tdb_off_t recovery_head;
642 enum TDB_ERROR ecode;
644 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
645 if (recovery_head == TDB_OFF_ERR) {
646 tdb_logerr(tdb, tdb->ecode, TDB_LOG_ERROR,
647 "tdb_recovery_allocate:"
648 " failed to read recovery head");
652 if (recovery_head != 0) {
653 ecode = methods->tread(tdb, recovery_head, &rec, sizeof(rec));
654 if (ecode != TDB_SUCCESS) {
655 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
656 "tdb_recovery_allocate:"
657 " failed to read recovery record");
660 tdb_convert(tdb, &rec, sizeof(rec));
661 /* ignore invalid recovery regions: can happen in crash */
662 if (rec.magic != TDB_RECOVERY_MAGIC &&
663 rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
668 *recovery_size = tdb_recovery_size(tdb);
670 if (recovery_head != 0 && *recovery_size <= rec.max_len) {
671 /* it fits in the existing area */
672 *recovery_max_size = rec.max_len;
673 *recovery_offset = recovery_head;
677 /* we need to free up the old recovery area, then allocate a
678 new one at the end of the file. Note that we cannot use
679 normal allocation to allocate the new one as that might return
680 us an area that is being currently used (as of the start of
682 if (recovery_head != 0) {
683 add_stat(tdb, frees, 1);
684 if (add_free_record(tdb, recovery_head,
685 sizeof(rec) + rec.max_len) != 0) {
686 tdb_logerr(tdb, tdb->ecode, TDB_LOG_ERROR,
687 "tdb_recovery_allocate:"
688 " failed to free previous recovery area");
693 /* the tdb_free() call might have increased the recovery size */
694 *recovery_size = tdb_recovery_size(tdb);
696 /* round up to a multiple of page size */
698 = (((sizeof(rec) + *recovery_size) + getpagesize()-1)
699 & ~(getpagesize()-1))
701 *recovery_offset = tdb->map_size;
702 recovery_head = *recovery_offset;
704 /* Restore ->map_size before calling underlying expand_file.
705 Also so that we don't try to expand the file again in the
706 transaction commit, which would destroy the recovery
708 addition = (tdb->map_size - tdb->transaction->old_map_size) +
709 sizeof(rec) + *recovery_max_size;
710 tdb->map_size = tdb->transaction->old_map_size;
711 ecode = methods->expand_file(tdb, addition);
712 if (ecode != TDB_SUCCESS) {
713 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
714 "tdb_recovery_allocate:"
715 " failed to create recovery area");
719 /* we have to reset the old map size so that we don't try to
720 expand the file again in the transaction commit, which
721 would destroy the recovery area */
722 tdb->transaction->old_map_size = tdb->map_size;
724 /* write the recovery header offset and sync - we can sync without a race here
725 as the magic ptr in the recovery record has not been set */
726 tdb_convert(tdb, &recovery_head, sizeof(recovery_head));
727 ecode = methods->twrite(tdb, offsetof(struct tdb_header, recovery),
728 &recovery_head, sizeof(tdb_off_t));
729 if (ecode != TDB_SUCCESS) {
730 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
731 "tdb_recovery_allocate:"
732 " failed to write recovery head");
735 transaction_write_existing(tdb, offsetof(struct tdb_header, recovery),
741 /* Set up header for the recovery record. */
742 static void set_recovery_header(struct tdb_recovery_record *rec,
744 uint64_t datalen, uint64_t actuallen,
748 rec->max_len = actuallen;
754 setup the recovery data that will be used on a crash during commit
756 static int transaction_setup_recovery(struct tdb_context *tdb,
757 tdb_off_t *magic_offset)
759 tdb_len_t recovery_size;
760 unsigned char *data, *p;
761 const struct tdb_methods *methods = tdb->transaction->io_methods;
762 struct tdb_recovery_record *rec;
763 tdb_off_t recovery_offset, recovery_max_size;
764 tdb_off_t old_map_size = tdb->transaction->old_map_size;
765 uint64_t magic, tailer;
767 enum TDB_ERROR ecode;
770 check that the recovery area has enough space
772 if (tdb_recovery_allocate(tdb, &recovery_size,
773 &recovery_offset, &recovery_max_size) == -1) {
777 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
779 tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
780 "transaction_setup_recovery: cannot allocate");
784 rec = (struct tdb_recovery_record *)data;
785 set_recovery_header(rec, TDB_RECOVERY_INVALID_MAGIC,
786 recovery_size, recovery_max_size, old_map_size);
787 tdb_convert(tdb, rec, sizeof(*rec));
789 /* build the recovery data into a single blob to allow us to do a single
790 large write, which should be more efficient */
791 p = data + sizeof(*rec);
792 for (i=0;i<tdb->transaction->num_blocks;i++) {
796 if (tdb->transaction->blocks[i] == NULL) {
800 offset = i * getpagesize();
801 length = getpagesize();
802 if (i == tdb->transaction->num_blocks-1) {
803 length = tdb->transaction->last_block_size;
806 if (offset >= old_map_size) {
809 if (offset + length > tdb->map_size) {
810 tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
811 "tdb_transaction_setup_recovery:"
812 " transaction data over new region boundary");
816 memcpy(p, &offset, sizeof(offset));
817 memcpy(p + sizeof(offset), &length, sizeof(length));
818 tdb_convert(tdb, p, sizeof(offset) + sizeof(length));
820 /* the recovery area contains the old data, not the
821 new data, so we have to call the original tdb_read
823 ecode = methods->tread(tdb, offset,
824 p + sizeof(offset) + sizeof(length),
826 if (ecode != TDB_SUCCESS) {
831 p += sizeof(offset) + sizeof(length) + length;
835 tailer = sizeof(*rec) + recovery_max_size;
836 memcpy(p, &tailer, sizeof(tailer));
837 tdb_convert(tdb, p, sizeof(tailer));
839 /* write the recovery data to the recovery area */
840 ecode = methods->twrite(tdb, recovery_offset, data,
841 sizeof(*rec) + recovery_size);
842 if (ecode != TDB_SUCCESS) {
843 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
844 "tdb_transaction_setup_recovery:"
845 " failed to write recovery data");
849 transaction_write_existing(tdb, recovery_offset, data,
850 sizeof(*rec) + recovery_size);
852 /* as we don't have ordered writes, we have to sync the recovery
853 data before we update the magic to indicate that the recovery
855 ecode = transaction_sync(tdb, recovery_offset,
856 sizeof(*rec) + recovery_size);
857 if (ecode != TDB_SUCCESS) {
865 magic = TDB_RECOVERY_MAGIC;
866 tdb_convert(tdb, &magic, sizeof(magic));
868 *magic_offset = recovery_offset + offsetof(struct tdb_recovery_record,
871 ecode = methods->twrite(tdb, *magic_offset, &magic, sizeof(magic));
872 if (ecode != TDB_SUCCESS) {
873 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
874 "tdb_transaction_setup_recovery:"
875 " failed to write recovery magic");
878 transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic));
880 /* ensure the recovery magic marker is on disk */
881 ecode = transaction_sync(tdb, *magic_offset, sizeof(magic));
882 if (ecode != TDB_SUCCESS) {
890 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
892 const struct tdb_methods *methods;
893 enum TDB_ERROR ecode;
895 if (tdb->transaction == NULL) {
896 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
897 "tdb_transaction_prepare_commit: no transaction");
901 if (tdb->transaction->prepared) {
902 _tdb_transaction_cancel(tdb);
903 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
904 "tdb_transaction_prepare_commit:"
905 " transaction already prepared");
909 if (tdb->transaction->transaction_error) {
910 _tdb_transaction_cancel(tdb);
911 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_ERROR,
912 "tdb_transaction_prepare_commit:"
913 " transaction error pending");
918 if (tdb->transaction->nesting != 0) {
919 tdb->transaction->nesting--;
923 /* check for a null transaction */
924 if (tdb->transaction->blocks == NULL) {
928 methods = tdb->transaction->io_methods;
930 /* upgrade the main transaction lock region to a write lock */
931 ecode = tdb_allrecord_upgrade(tdb);
932 if (ecode != TDB_SUCCESS) {
933 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
934 "tdb_transaction_prepare_commit:"
935 " failed to upgrade hash locks");
936 _tdb_transaction_cancel(tdb);
940 /* get the open lock - this prevents new users attaching to the database
942 ecode = tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK);
943 if (ecode != TDB_SUCCESS) {
944 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
945 "tdb_transaction_prepare_commit:"
946 " failed to get open lock");
947 _tdb_transaction_cancel(tdb);
951 /* Since we have whole db locked, we don't need the expansion lock. */
952 if (!(tdb->flags & TDB_NOSYNC)) {
953 /* write the recovery data to the end of the file */
954 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
955 tdb_logerr(tdb, tdb->ecode, TDB_LOG_ERROR,
956 "tdb_transaction_prepare_commit:"
957 " failed to setup recovery data");
958 _tdb_transaction_cancel(tdb);
963 tdb->transaction->prepared = true;
965 /* expand the file to the new size if needed */
966 if (tdb->map_size != tdb->transaction->old_map_size) {
967 tdb_len_t add = tdb->map_size - tdb->transaction->old_map_size;
968 /* Restore original map size for tdb_expand_file */
969 tdb->map_size = tdb->transaction->old_map_size;
970 ecode = methods->expand_file(tdb, add);
971 if (ecode != TDB_SUCCESS) {
972 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
973 "tdb_transaction_prepare_commit:"
974 " expansion failed");
975 _tdb_transaction_cancel(tdb);
980 /* Keep the open lock until the actual commit */
986 prepare to commit the current transaction
988 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
990 return _tdb_transaction_prepare_commit(tdb);
994 commit the current transaction
996 int tdb_transaction_commit(struct tdb_context *tdb)
998 const struct tdb_methods *methods;
1000 enum TDB_ERROR ecode;
1002 if (tdb->transaction == NULL) {
1003 tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
1004 "tdb_transaction_commit: no transaction");
1008 tdb_trace(tdb, "tdb_transaction_commit");
1010 if (tdb->transaction->nesting != 0) {
1011 tdb->transaction->nesting--;
1015 /* check for a null transaction */
1016 if (tdb->transaction->blocks == NULL) {
1017 _tdb_transaction_cancel(tdb);
1021 if (!tdb->transaction->prepared) {
1022 int ret = _tdb_transaction_prepare_commit(tdb);
1027 methods = tdb->transaction->io_methods;
1029 /* perform all the writes */
1030 for (i=0;i<tdb->transaction->num_blocks;i++) {
1034 if (tdb->transaction->blocks[i] == NULL) {
1038 offset = i * getpagesize();
1039 length = getpagesize();
1040 if (i == tdb->transaction->num_blocks-1) {
1041 length = tdb->transaction->last_block_size;
1044 ecode = methods->twrite(tdb, offset,
1045 tdb->transaction->blocks[i], length);
1046 if (ecode != TDB_SUCCESS) {
1047 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1048 "tdb_transaction_commit:"
1049 " write failed during commit");
1051 /* we've overwritten part of the data and
1052 possibly expanded the file, so we need to
1053 run the crash recovery code */
1054 tdb->methods = methods;
1055 tdb_transaction_recover(tdb);
1057 _tdb_transaction_cancel(tdb);
1061 SAFE_FREE(tdb->transaction->blocks[i]);
1064 SAFE_FREE(tdb->transaction->blocks);
1065 tdb->transaction->num_blocks = 0;
1067 /* ensure the new data is on disk */
1068 ecode = transaction_sync(tdb, 0, tdb->map_size);
1069 if (ecode != TDB_SUCCESS) {
1075 TODO: maybe write to some dummy hdr field, or write to magic
1076 offset without mmap, before the last sync, instead of the
1080 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1081 don't change the mtime of the file, this means the file may
1082 not be backed up (as tdb rounding to block sizes means that
1083 file size changes are quite rare too). The following forces
1084 mtime changes when a transaction completes */
1086 utime(tdb->name, NULL);
1089 /* use a transaction cancel to free memory and remove the
1090 transaction locks */
1091 _tdb_transaction_cancel(tdb);
1098 recover from an aborted transaction. Must be called with exclusive
1099 database write access already established (including the open
1100 lock to prevent new processes attaching)
1102 int tdb_transaction_recover(struct tdb_context *tdb)
1104 tdb_off_t recovery_head, recovery_eof;
1105 unsigned char *data, *p;
1106 struct tdb_recovery_record rec;
1107 enum TDB_ERROR ecode;
1109 /* find the recovery area */
1110 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
1111 if (recovery_head == TDB_OFF_ERR) {
1112 tdb_logerr(tdb, tdb->ecode, TDB_LOG_ERROR,
1113 "tdb_transaction_recover:"
1114 " failed to read recovery head");
1118 if (recovery_head == 0) {
1119 /* we have never allocated a recovery record */
1123 /* read the recovery record */
1124 ecode = tdb_read_convert(tdb, recovery_head, &rec, sizeof(rec));
1125 if (ecode != TDB_SUCCESS) {
1126 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1127 "tdb_transaction_recover:"
1128 " failed to read recovery record");
1132 if (rec.magic != TDB_RECOVERY_MAGIC) {
1133 /* there is no valid recovery data */
1137 if (tdb->read_only) {
1138 tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
1139 "tdb_transaction_recover:"
1140 " attempt to recover read only database");
1144 recovery_eof = rec.eof;
1146 data = (unsigned char *)malloc(rec.len);
1148 tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
1149 "tdb_transaction_recover:"
1150 " failed to allocate recovery data");
1154 /* read the full recovery data */
1155 ecode = tdb->methods->tread(tdb, recovery_head + sizeof(rec), data,
1157 if (ecode != TDB_SUCCESS) {
1158 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1159 "tdb_transaction_recover:"
1160 " failed to read recovery data");
1164 /* recover the file data */
1166 while (p+sizeof(tdb_off_t)+sizeof(tdb_len_t) < data + rec.len) {
1169 tdb_convert(tdb, p, sizeof(ofs) + sizeof(len));
1170 memcpy(&ofs, p, sizeof(ofs));
1171 memcpy(&len, p + sizeof(ofs), sizeof(len));
1172 p += sizeof(ofs) + sizeof(len);
1174 ecode = tdb->methods->twrite(tdb, ofs, p, len);
1175 if (ecode != TDB_SUCCESS) {
1177 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1178 "tdb_transaction_recover:"
1179 " failed to recover %zu bytes at offset %zu",
1180 (size_t)len, (size_t)ofs);
1188 ecode = transaction_sync(tdb, 0, tdb->map_size);
1189 if (ecode != TDB_SUCCESS) {
1190 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1191 "tdb_transaction_recover: failed to sync recovery");
1195 /* if the recovery area is after the recovered eof then remove it */
1196 if (recovery_eof <= recovery_head) {
1197 ecode = tdb_write_off(tdb, offsetof(struct tdb_header,
1200 if (ecode != TDB_SUCCESS) {
1201 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1202 "tdb_transaction_recover:"
1203 " failed to remove recovery head");
1208 /* remove the recovery magic */
1209 ecode = tdb_write_off(tdb,
1211 + offsetof(struct tdb_recovery_record, magic),
1212 TDB_RECOVERY_INVALID_MAGIC);
1213 if (ecode != TDB_SUCCESS) {
1214 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1215 "tdb_transaction_recover:"
1216 " failed to remove recovery magic");
1220 ecode = transaction_sync(tdb, 0, recovery_eof);
1221 if (ecode != TDB_SUCCESS) {
1222 tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
1223 "tdb_transaction_recover: failed to sync2 recovery");
1227 tdb_logerr(tdb, TDB_SUCCESS, TDB_LOG_WARNING,
1228 "tdb_transaction_recover: recovered %zu byte database",
1229 (size_t)recovery_eof);
1235 /* Any I/O failures we say "needs recovery". */
1236 bool tdb_needs_recovery(struct tdb_context *tdb)
1238 tdb_off_t recovery_head;
1239 struct tdb_recovery_record rec;
1240 enum TDB_ERROR ecode;
1242 /* find the recovery area */
1243 recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
1244 if (recovery_head == TDB_OFF_ERR) {
1248 if (recovery_head == 0) {
1249 /* we have never allocated a recovery record */
1253 /* read the recovery record */
1254 ecode = tdb_read_convert(tdb, recovery_head, &rec, sizeof(rec));
1255 if (ecode != TDB_SUCCESS) {
1260 return (rec.magic == TDB_RECOVERY_MAGIC);