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 "tdb1_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 tdb1_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 tdb1_write() calls. The hooked
48 transaction versions of tdb1_read() and tdb1_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 tdb1_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 tdb1_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 tdb1_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 tdb1_add_flags() transaction nesting is enabled.
90 The default is that transaction nesting is NOT allowed.
92 Beware. when transactions are nested a transaction successfully
93 completed with tdb1_transaction_commit() can be silently unrolled later.
98 hold the context of any current transaction
100 struct tdb1_transaction {
101 /* we keep a mirrored copy of the tdb hash heads here so
102 tdb1_next_hash_chain() can operate efficiently */
103 uint32_t *hash_heads;
105 /* the original io methods - used to do IOs to the real db */
106 const struct tdb1_methods *io_methods;
108 /* the list of transaction blocks. When a block is first
109 written to, it gets created in this list */
112 uint32_t block_size; /* bytes in each block */
113 uint32_t last_block_size; /* number of valid bytes in the last block */
115 /* non-zero when an internal transaction error has
116 occurred. All write operations will then fail until the
117 transaction is ended */
118 int transaction_error;
120 /* when inside a transaction we need to keep track of any
121 nested tdb1_transaction_start() calls, as these are allowed,
122 but don't create a new transaction */
125 /* set when a prepare has already occurred */
127 tdb1_off_t magic_offset;
129 /* old file size before transaction */
130 tdb1_len_t old_map_size;
132 /* did we expand in this transaction */
138 read while in a transaction. We need to check first if the data is in our list
139 of transaction elements, then if not do a real read
141 static int transaction1_read(struct tdb_context *tdb, tdb1_off_t off, void *buf,
142 tdb1_len_t len, int cv)
146 /* break it down into block sized ops */
147 while (len + (off % tdb->tdb1.transaction->block_size) > tdb->tdb1.transaction->block_size) {
148 tdb1_len_t len2 = tdb->tdb1.transaction->block_size - (off % tdb->tdb1.transaction->block_size);
149 if (transaction1_read(tdb, off, buf, len2, cv) != 0) {
154 buf = (void *)(len2 + (char *)buf);
161 blk = off / tdb->tdb1.transaction->block_size;
163 /* see if we have it in the block list */
164 if (tdb->tdb1.transaction->num_blocks <= blk ||
165 tdb->tdb1.transaction->blocks[blk] == NULL) {
166 /* nope, do a real read */
167 if (tdb->tdb1.transaction->io_methods->tdb1_read(tdb, off, buf, len, cv) != 0) {
173 /* it is in the block list. Now check for the last block */
174 if (blk == tdb->tdb1.transaction->num_blocks-1) {
175 if (len > tdb->tdb1.transaction->last_block_size) {
180 /* now copy it out of this block */
181 memcpy(buf, tdb->tdb1.transaction->blocks[blk] + (off % tdb->tdb1.transaction->block_size), len);
183 tdb1_convert(buf, len);
188 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
189 "transaction_read: failed at off=%d len=%d",
191 tdb->tdb1.transaction->transaction_error = 1;
197 write while in a transaction
199 static int transaction1_write(struct tdb_context *tdb, tdb1_off_t off,
200 const void *buf, tdb1_len_t len)
204 /* Only a commit is allowed on a prepared transaction */
205 if (tdb->tdb1.transaction->prepared) {
206 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
207 "transaction_write: transaction already"
208 " prepared, write not allowed");
209 tdb->tdb1.transaction->transaction_error = 1;
213 /* if the write is to a hash head, then update the transaction
215 if (len == sizeof(tdb1_off_t) && off >= TDB1_FREELIST_TOP &&
216 off < TDB1_FREELIST_TOP+TDB1_HASHTABLE_SIZE(tdb)) {
217 uint32_t chain = (off-TDB1_FREELIST_TOP) / sizeof(tdb1_off_t);
218 memcpy(&tdb->tdb1.transaction->hash_heads[chain], buf, len);
221 /* break it up into block sized chunks */
222 while (len + (off % tdb->tdb1.transaction->block_size) > tdb->tdb1.transaction->block_size) {
223 tdb1_len_t len2 = tdb->tdb1.transaction->block_size - (off % tdb->tdb1.transaction->block_size);
224 if (transaction1_write(tdb, off, buf, len2) != 0) {
230 buf = (const void *)(len2 + (const char *)buf);
238 blk = off / tdb->tdb1.transaction->block_size;
239 off = off % tdb->tdb1.transaction->block_size;
241 if (tdb->tdb1.transaction->num_blocks <= blk) {
242 uint8_t **new_blocks;
243 /* expand the blocks array */
244 if (tdb->tdb1.transaction->blocks == NULL) {
245 new_blocks = (uint8_t **)malloc(
246 (blk+1)*sizeof(uint8_t *));
248 new_blocks = (uint8_t **)realloc(
249 tdb->tdb1.transaction->blocks,
250 (blk+1)*sizeof(uint8_t *));
252 if (new_blocks == NULL) {
253 tdb->last_error = TDB_ERR_OOM;
256 memset(&new_blocks[tdb->tdb1.transaction->num_blocks], 0,
257 (1+(blk - tdb->tdb1.transaction->num_blocks))*sizeof(uint8_t *));
258 tdb->tdb1.transaction->blocks = new_blocks;
259 tdb->tdb1.transaction->num_blocks = blk+1;
260 tdb->tdb1.transaction->last_block_size = 0;
263 /* allocate and fill a block? */
264 if (tdb->tdb1.transaction->blocks[blk] == NULL) {
265 tdb->tdb1.transaction->blocks[blk] = (uint8_t *)calloc(tdb->tdb1.transaction->block_size, 1);
266 if (tdb->tdb1.transaction->blocks[blk] == NULL) {
267 tdb->last_error = TDB_ERR_OOM;
268 tdb->tdb1.transaction->transaction_error = 1;
271 if (tdb->tdb1.transaction->old_map_size > blk * tdb->tdb1.transaction->block_size) {
272 tdb1_len_t len2 = tdb->tdb1.transaction->block_size;
273 if (len2 + (blk * tdb->tdb1.transaction->block_size) > tdb->tdb1.transaction->old_map_size) {
274 len2 = tdb->tdb1.transaction->old_map_size - (blk * tdb->tdb1.transaction->block_size);
276 if (tdb->tdb1.transaction->io_methods->tdb1_read(tdb, blk * tdb->tdb1.transaction->block_size,
277 tdb->tdb1.transaction->blocks[blk],
279 SAFE_FREE(tdb->tdb1.transaction->blocks[blk]);
280 tdb->last_error = TDB_ERR_IO;
283 if (blk == tdb->tdb1.transaction->num_blocks-1) {
284 tdb->tdb1.transaction->last_block_size = len2;
289 /* overwrite part of an existing block */
291 memset(tdb->tdb1.transaction->blocks[blk] + off, 0, len);
293 memcpy(tdb->tdb1.transaction->blocks[blk] + off, buf, len);
295 if (blk == tdb->tdb1.transaction->num_blocks-1) {
296 if (len + off > tdb->tdb1.transaction->last_block_size) {
297 tdb->tdb1.transaction->last_block_size = len + off;
304 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
305 "transaction_write: failed at off=%d len=%d",
306 (blk*tdb->tdb1.transaction->block_size) + off, len);
307 tdb->tdb1.transaction->transaction_error = 1;
313 write while in a transaction - this varient never expands the transaction blocks, it only
314 updates existing blocks. This means it cannot change the recovery size
316 static int transaction1_write_existing(struct tdb_context *tdb, tdb1_off_t off,
317 const void *buf, tdb1_len_t len)
321 /* break it up into block sized chunks */
322 while (len + (off % tdb->tdb1.transaction->block_size) > tdb->tdb1.transaction->block_size) {
323 tdb1_len_t len2 = tdb->tdb1.transaction->block_size - (off % tdb->tdb1.transaction->block_size);
324 if (transaction1_write_existing(tdb, off, buf, len2) != 0) {
330 buf = (const void *)(len2 + (const char *)buf);
338 blk = off / tdb->tdb1.transaction->block_size;
339 off = off % tdb->tdb1.transaction->block_size;
341 if (tdb->tdb1.transaction->num_blocks <= blk ||
342 tdb->tdb1.transaction->blocks[blk] == NULL) {
346 if (blk == tdb->tdb1.transaction->num_blocks-1 &&
347 off + len > tdb->tdb1.transaction->last_block_size) {
348 if (off >= tdb->tdb1.transaction->last_block_size) {
351 len = tdb->tdb1.transaction->last_block_size - off;
354 /* overwrite part of an existing block */
355 memcpy(tdb->tdb1.transaction->blocks[blk] + off, buf, len);
362 accelerated hash chain head search, using the cached hash heads
364 static void transaction1_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
367 for (;h < tdb->tdb1.header.hash_size;h++) {
368 /* the +1 takes account of the freelist */
369 if (0 != tdb->tdb1.transaction->hash_heads[h+1]) {
377 out of bounds check during a transaction
379 static int transaction1_oob(struct tdb_context *tdb, tdb1_off_t len, int probe)
381 if (len <= tdb->file->map_size) {
384 tdb->last_error = TDB_ERR_IO;
389 transaction version of tdb1_expand().
391 static int transaction1_expand_file(struct tdb_context *tdb, tdb1_off_t size,
394 /* add a write to the transaction elements, so subsequent
395 reads see the zero data */
396 if (transaction1_write(tdb, size, NULL, addition) != 0) {
400 tdb->tdb1.transaction->expanded = true;
405 static const struct tdb1_methods transaction1_methods = {
408 transaction1_next_hash_chain,
410 transaction1_expand_file,
415 start a tdb transaction. No token is returned, as only a single
416 transaction is allowed to be pending per tdb_context
418 static int _tdb1_transaction_start(struct tdb_context *tdb)
420 /* some sanity checks */
421 if ((tdb->flags & TDB_RDONLY) || (tdb->flags & TDB_INTERNAL) || tdb->tdb1.traverse_read) {
422 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
423 "tdb1_transaction_start: cannot start a"
424 " transaction on a read-only or"
429 /* cope with nested tdb1_transaction_start() calls */
430 if (tdb->tdb1.transaction != NULL) {
431 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
432 tdb->last_error = TDB_ERR_EINVAL;
435 tdb->tdb1.transaction->nesting++;
439 if (tdb1_have_extra_locks(tdb)) {
440 /* the caller must not have any locks when starting a
441 transaction as otherwise we'll be screwed by lack
442 of nested locks in posix */
443 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
444 "tdb1_transaction_start: cannot start a"
445 " transaction with locks held");
449 if (tdb->tdb1.travlocks.next != NULL) {
450 /* you cannot use transactions inside a traverse (although you can use
451 traverse inside a transaction) as otherwise you can end up with
453 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
454 "tdb1_transaction_start: cannot start a"
455 " transaction within a traverse");
459 tdb->tdb1.transaction = (struct tdb1_transaction *)
460 calloc(sizeof(struct tdb1_transaction), 1);
461 if (tdb->tdb1.transaction == NULL) {
462 tdb->last_error = TDB_ERR_OOM;
466 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
467 tdb->tdb1.transaction->block_size = tdb->tdb1.page_size;
469 /* get the transaction write lock. This is a blocking lock. As
470 discussed with Volker, there are a number of ways we could
471 make this async, which we will probably do in the future */
472 if (tdb1_transaction_lock(tdb, F_WRLCK, TDB_LOCK_WAIT) == -1) {
473 SAFE_FREE(tdb->tdb1.transaction->blocks);
474 SAFE_FREE(tdb->tdb1.transaction);
478 /* get a read lock from the freelist to the end of file. This
479 is upgraded to a write lock during the commit */
480 if (tdb1_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
481 if (errno != EAGAIN && errno != EINTR) {
482 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
483 "tdb1_transaction_start:"
484 " failed to get hash locks");
486 goto fail_allrecord_lock;
489 /* setup a copy of the hash table heads so the hash scan in
490 traverse can be fast */
491 tdb->tdb1.transaction->hash_heads = (uint32_t *)
492 calloc(tdb->tdb1.header.hash_size+1, sizeof(uint32_t));
493 if (tdb->tdb1.transaction->hash_heads == NULL) {
494 tdb->last_error = TDB_ERR_OOM;
497 if (tdb->tdb1.io->tdb1_read(tdb, TDB1_FREELIST_TOP, tdb->tdb1.transaction->hash_heads,
498 TDB1_HASHTABLE_SIZE(tdb), 0) != 0) {
499 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
500 "tdb1_transaction_start: failed to read hash heads");
504 /* make sure we know about any file expansions already done by
506 tdb->tdb1.io->tdb1_oob(tdb, tdb->file->map_size + 1, 1);
507 tdb->tdb1.transaction->old_map_size = tdb->file->map_size;
509 /* finally hook the io methods, replacing them with
510 transaction specific methods */
511 tdb->tdb1.transaction->io_methods = tdb->tdb1.io;
512 tdb->tdb1.io = &transaction1_methods;
517 tdb1_allrecord_unlock(tdb, F_RDLCK);
519 tdb1_transaction_unlock(tdb, F_WRLCK);
520 SAFE_FREE(tdb->tdb1.transaction->blocks);
521 SAFE_FREE(tdb->tdb1.transaction->hash_heads);
522 SAFE_FREE(tdb->tdb1.transaction);
526 int tdb1_transaction_start(struct tdb_context *tdb)
528 return _tdb1_transaction_start(tdb);
534 static int transaction1_sync(struct tdb_context *tdb, tdb1_off_t offset, tdb1_len_t length)
536 if (tdb->flags & TDB_NOSYNC) {
541 if (fdatasync(tdb->file->fd) != 0) {
543 if (fsync(tdb->file->fd) != 0) {
545 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
546 "tdb1_transaction: fsync failed");
550 if (tdb->file->map_ptr) {
551 tdb1_off_t moffset = offset & ~(tdb->tdb1.page_size-1);
552 if (msync(moffset + (char *)tdb->file->map_ptr,
553 length + (offset - moffset), MS_SYNC) != 0) {
554 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
556 " msync failed - %s",
566 static int _tdb1_transaction_cancel(struct tdb_context *tdb)
570 if (tdb->tdb1.transaction == NULL) {
571 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
572 "tdb1_transaction_cancel:"
577 if (tdb->tdb1.transaction->nesting != 0) {
578 tdb->tdb1.transaction->transaction_error = 1;
579 tdb->tdb1.transaction->nesting--;
583 tdb->file->map_size = tdb->tdb1.transaction->old_map_size;
585 /* free all the transaction blocks */
586 for (i=0;i<tdb->tdb1.transaction->num_blocks;i++) {
587 if (tdb->tdb1.transaction->blocks[i] != NULL) {
588 free(tdb->tdb1.transaction->blocks[i]);
591 SAFE_FREE(tdb->tdb1.transaction->blocks);
593 if (tdb->tdb1.transaction->magic_offset) {
594 const struct tdb1_methods *methods = tdb->tdb1.transaction->io_methods;
595 const uint32_t invalid = TDB1_RECOVERY_INVALID_MAGIC;
597 /* remove the recovery marker */
598 if (methods->tdb1_write(tdb, tdb->tdb1.transaction->magic_offset, &invalid, 4) == -1 ||
599 transaction1_sync(tdb, tdb->tdb1.transaction->magic_offset, 4) == -1) {
600 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
601 "tdb1_transaction_cancel: failed to"
602 " remove recovery magic");
607 /* This also removes the OPEN_LOCK, if we have it. */
608 tdb1_release_transaction_locks(tdb);
610 /* restore the normal io methods */
611 tdb->tdb1.io = tdb->tdb1.transaction->io_methods;
613 SAFE_FREE(tdb->tdb1.transaction->hash_heads);
614 SAFE_FREE(tdb->tdb1.transaction);
620 cancel the current transaction
622 int tdb1_transaction_cancel(struct tdb_context *tdb)
624 return _tdb1_transaction_cancel(tdb);
628 work out how much space the linearised recovery data will consume
630 static tdb1_len_t tdb1_recovery_size(struct tdb_context *tdb)
632 tdb1_len_t recovery_size = 0;
635 recovery_size = sizeof(uint32_t);
636 for (i=0;i<tdb->tdb1.transaction->num_blocks;i++) {
637 if (i * tdb->tdb1.transaction->block_size >= tdb->tdb1.transaction->old_map_size) {
640 if (tdb->tdb1.transaction->blocks[i] == NULL) {
643 recovery_size += 2*sizeof(tdb1_off_t);
644 if (i == tdb->tdb1.transaction->num_blocks-1) {
645 recovery_size += tdb->tdb1.transaction->last_block_size;
647 recovery_size += tdb->tdb1.transaction->block_size;
651 return recovery_size;
654 int tdb1_recovery_area(struct tdb_context *tdb,
655 const struct tdb1_methods *methods,
656 tdb1_off_t *recovery_offset,
657 struct tdb1_record *rec)
659 if (tdb1_ofs_read(tdb, TDB1_RECOVERY_HEAD, recovery_offset) == -1) {
663 if (*recovery_offset == 0) {
668 if (methods->tdb1_read(tdb, *recovery_offset, rec, sizeof(*rec),
669 TDB1_DOCONV()) == -1) {
673 /* ignore invalid recovery regions: can happen in crash */
674 if (rec->magic != TDB1_RECOVERY_MAGIC &&
675 rec->magic != TDB1_RECOVERY_INVALID_MAGIC) {
676 *recovery_offset = 0;
683 allocate the recovery area, or use an existing recovery area if it is
686 static int tdb1_recovery_allocate(struct tdb_context *tdb,
687 tdb1_len_t *recovery_size,
688 tdb1_off_t *recovery_offset,
689 tdb1_len_t *recovery_max_size)
691 struct tdb1_record rec;
692 const struct tdb1_methods *methods = tdb->tdb1.transaction->io_methods;
693 tdb1_off_t recovery_head;
695 if (tdb1_recovery_area(tdb, methods, &recovery_head, &rec) == -1) {
696 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
697 "tdb1_recovery_allocate:"
698 " failed to read recovery head");
702 *recovery_size = tdb1_recovery_size(tdb);
704 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
705 /* it fits in the existing area */
706 *recovery_max_size = rec.rec_len;
707 *recovery_offset = recovery_head;
711 /* we need to free up the old recovery area, then allocate a
712 new one at the end of the file. Note that we cannot use
713 tdb1_allocate() to allocate the new one as that might return
714 us an area that is being currently used (as of the start of
716 if (recovery_head != 0) {
717 if (tdb1_free(tdb, recovery_head, &rec) == -1) {
718 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
719 "tdb1_recovery_allocate: failed to free"
720 " previous recovery area");
725 /* the tdb1_free() call might have increased the recovery size */
726 *recovery_size = tdb1_recovery_size(tdb);
728 /* round up to a multiple of page size */
729 *recovery_max_size = TDB1_ALIGN(sizeof(rec) + *recovery_size,
730 tdb->tdb1.page_size) - sizeof(rec);
731 *recovery_offset = tdb->file->map_size;
732 recovery_head = *recovery_offset;
734 if (methods->tdb1_expand_file(tdb, tdb->tdb1.transaction->old_map_size,
735 (tdb->file->map_size - tdb->tdb1.transaction->old_map_size) +
736 sizeof(rec) + *recovery_max_size) == -1) {
737 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
738 "tdb1_recovery_allocate:"
739 " failed to create recovery area");
743 /* remap the file (if using mmap) */
744 methods->tdb1_oob(tdb, tdb->file->map_size + 1, 1);
746 /* we have to reset the old map size so that we don't try to expand the file
747 again in the transaction commit, which would destroy the recovery area */
748 tdb->tdb1.transaction->old_map_size = tdb->file->map_size;
750 /* write the recovery header offset and sync - we can sync without a race here
751 as the magic ptr in the recovery record has not been set */
752 TDB1_CONV(recovery_head);
753 if (methods->tdb1_write(tdb, TDB1_RECOVERY_HEAD,
754 &recovery_head, sizeof(tdb1_off_t)) == -1) {
755 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
756 "tdb1_recovery_allocate:"
757 " failed to write recovery head");
760 if (transaction1_write_existing(tdb, TDB1_RECOVERY_HEAD, &recovery_head, sizeof(tdb1_off_t)) == -1) {
761 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
762 "tdb1_recovery_allocate:"
763 " failed to write recovery head");
772 setup the recovery data that will be used on a crash during commit
774 static int transaction1_setup_recovery(struct tdb_context *tdb,
775 tdb1_off_t *magic_offset)
777 tdb1_len_t recovery_size;
778 unsigned char *data, *p;
779 const struct tdb1_methods *methods = tdb->tdb1.transaction->io_methods;
780 struct tdb1_record *rec;
781 tdb1_off_t recovery_offset, recovery_max_size;
782 tdb1_off_t old_map_size = tdb->tdb1.transaction->old_map_size;
783 uint32_t magic, tailer;
787 check that the recovery area has enough space
789 if (tdb1_recovery_allocate(tdb, &recovery_size,
790 &recovery_offset, &recovery_max_size) == -1) {
794 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
796 tdb->last_error = TDB_ERR_OOM;
800 rec = (struct tdb1_record *)data;
801 memset(rec, 0, sizeof(*rec));
803 rec->magic = TDB1_RECOVERY_INVALID_MAGIC;
804 rec->data_len = recovery_size;
805 rec->rec_len = recovery_max_size;
806 rec->key_len = old_map_size;
809 /* build the recovery data into a single blob to allow us to do a single
810 large write, which should be more efficient */
811 p = data + sizeof(*rec);
812 for (i=0;i<tdb->tdb1.transaction->num_blocks;i++) {
816 if (tdb->tdb1.transaction->blocks[i] == NULL) {
820 offset = i * tdb->tdb1.transaction->block_size;
821 length = tdb->tdb1.transaction->block_size;
822 if (i == tdb->tdb1.transaction->num_blocks-1) {
823 length = tdb->tdb1.transaction->last_block_size;
826 if (offset >= old_map_size) {
829 if (offset + length > tdb->tdb1.transaction->old_map_size) {
830 tdb->last_error = tdb_logerr(tdb, TDB_ERR_CORRUPT,
832 "tdb1_transaction_setup_recovery: transaction data over new region boundary");
836 memcpy(p, &offset, 4);
837 memcpy(p+4, &length, 4);
841 /* the recovery area contains the old data, not the
842 new data, so we have to call the original tdb1_read
844 if (methods->tdb1_read(tdb, offset, p + 8, length, 0) != 0) {
846 tdb->last_error = TDB_ERR_IO;
853 tailer = sizeof(*rec) + recovery_max_size;
854 memcpy(p, &tailer, 4);
859 /* write the recovery data to the recovery area */
860 if (methods->tdb1_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
861 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
862 "tdb1_transaction_setup_recovery:"
863 " failed to write recovery data");
867 if (transaction1_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
868 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
869 "tdb1_transaction_setup_recovery: failed to write"
870 " secondary recovery data");
875 /* as we don't have ordered writes, we have to sync the recovery
876 data before we update the magic to indicate that the recovery
878 if (transaction1_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
885 magic = TDB1_RECOVERY_MAGIC;
888 *magic_offset = recovery_offset + offsetof(struct tdb1_record, magic);
890 if (methods->tdb1_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
891 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
892 "tdb1_transaction_setup_recovery:"
893 " failed to write recovery magic");
896 if (transaction1_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
897 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
898 "tdb1_transaction_setup_recovery:"
899 " failed to write secondary recovery magic");
903 /* ensure the recovery magic marker is on disk */
904 if (transaction1_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
911 static int _tdb1_transaction_prepare_commit(struct tdb_context *tdb)
913 const struct tdb1_methods *methods;
915 if (tdb->tdb1.transaction == NULL) {
916 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
917 "tdb1_transaction_prepare_commit:"
922 if (tdb->tdb1.transaction->prepared) {
923 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
924 "tdb1_transaction_prepare_commit:"
925 " transaction already prepared");
926 _tdb1_transaction_cancel(tdb);
930 if (tdb->tdb1.transaction->transaction_error) {
931 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
932 "tdb1_transaction_prepare_commit:"
933 " transaction error pending");
934 _tdb1_transaction_cancel(tdb);
939 if (tdb->tdb1.transaction->nesting != 0) {
943 /* check for a null transaction */
944 if (tdb->tdb1.transaction->blocks == NULL) {
948 methods = tdb->tdb1.transaction->io_methods;
950 /* if there are any locks pending then the caller has not
951 nested their locks properly, so fail the transaction */
952 if (tdb1_have_extra_locks(tdb)) {
953 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
954 "tdb1_transaction_prepare_commit:"
955 " locks pending on commit");
956 _tdb1_transaction_cancel(tdb);
960 /* upgrade the main transaction lock region to a write lock */
961 if (tdb1_allrecord_upgrade(tdb) == -1) {
962 if (errno != EAGAIN && errno != EINTR) {
963 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
964 "tdb1_transaction_prepare_commit:"
965 " failed to upgrade hash locks");
970 /* get the open lock - this prevents new users attaching to the database
972 if (tdb1_nest_lock(tdb, TDB1_OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
973 if (errno != EAGAIN && errno != EINTR) {
974 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
975 "tdb1_transaction_prepare_commit:"
976 " failed to get open lock");
981 if (!(tdb->flags & TDB_NOSYNC)) {
982 /* write the recovery data to the end of the file */
983 if (transaction1_setup_recovery(tdb, &tdb->tdb1.transaction->magic_offset) == -1) {
984 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
985 "tdb1_transaction_prepare_commit:"
986 " failed to setup recovery data");
991 tdb->tdb1.transaction->prepared = true;
993 /* expand the file to the new size if needed */
994 if (tdb->file->map_size != tdb->tdb1.transaction->old_map_size) {
995 if (methods->tdb1_expand_file(tdb, tdb->tdb1.transaction->old_map_size,
996 tdb->file->map_size -
997 tdb->tdb1.transaction->old_map_size) == -1) {
998 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
999 "tdb1_transaction_prepare_commit:"
1000 " expansion failed");
1003 tdb->file->map_size = tdb->tdb1.transaction->old_map_size;
1004 methods->tdb1_oob(tdb, tdb->file->map_size + 1, 1);
1007 /* Keep the open lock until the actual commit */
1013 prepare to commit the current transaction
1015 int tdb1_transaction_prepare_commit(struct tdb_context *tdb)
1017 return _tdb1_transaction_prepare_commit(tdb);
1020 /* A repack is worthwhile if the largest is less than half total free. */
1021 static bool repack_worthwhile(struct tdb_context *tdb)
1024 struct tdb1_record rec;
1025 tdb1_len_t total = 0, largest = 0;
1027 if (tdb1_ofs_read(tdb, TDB1_FREELIST_TOP, &ptr) == -1) {
1031 while (ptr != 0 && tdb1_rec_free_read(tdb, ptr, &rec) == 0) {
1032 total += rec.rec_len;
1033 if (rec.rec_len > largest) {
1034 largest = rec.rec_len;
1039 return total > largest * 2;
1043 commit the current transaction
1045 int tdb1_transaction_commit(struct tdb_context *tdb)
1047 const struct tdb1_methods *methods;
1049 bool need_repack = false;
1051 if (tdb->tdb1.transaction == NULL) {
1052 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
1053 "tdb1_transaction_commit:"
1058 if (tdb->tdb1.transaction->transaction_error) {
1059 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
1060 "tdb1_transaction_commit:"
1061 " transaction error pending");
1062 _tdb1_transaction_cancel(tdb);
1067 if (tdb->tdb1.transaction->nesting != 0) {
1068 tdb->tdb1.transaction->nesting--;
1072 /* check for a null transaction */
1073 if (tdb->tdb1.transaction->blocks == NULL) {
1074 _tdb1_transaction_cancel(tdb);
1078 if (!tdb->tdb1.transaction->prepared) {
1079 int ret = _tdb1_transaction_prepare_commit(tdb);
1081 _tdb1_transaction_cancel(tdb);
1086 methods = tdb->tdb1.transaction->io_methods;
1088 /* perform all the writes */
1089 for (i=0;i<tdb->tdb1.transaction->num_blocks;i++) {
1093 if (tdb->tdb1.transaction->blocks[i] == NULL) {
1097 offset = i * tdb->tdb1.transaction->block_size;
1098 length = tdb->tdb1.transaction->block_size;
1099 if (i == tdb->tdb1.transaction->num_blocks-1) {
1100 length = tdb->tdb1.transaction->last_block_size;
1103 if (methods->tdb1_write(tdb, offset, tdb->tdb1.transaction->blocks[i], length) == -1) {
1104 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1105 "tdb1_transaction_commit:"
1106 " write failed during commit");
1108 /* we've overwritten part of the data and
1109 possibly expanded the file, so we need to
1110 run the crash recovery code */
1111 tdb->tdb1.io = methods;
1112 tdb1_transaction_recover(tdb);
1114 _tdb1_transaction_cancel(tdb);
1116 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1117 "tdb1_transaction_commit: write failed");
1120 SAFE_FREE(tdb->tdb1.transaction->blocks[i]);
1123 /* Do this before we drop lock or blocks. */
1124 if (tdb->tdb1.transaction->expanded) {
1125 need_repack = repack_worthwhile(tdb);
1128 SAFE_FREE(tdb->tdb1.transaction->blocks);
1129 tdb->tdb1.transaction->num_blocks = 0;
1131 /* ensure the new data is on disk */
1132 if (transaction1_sync(tdb, 0, tdb->file->map_size) == -1) {
1137 TODO: maybe write to some dummy hdr field, or write to magic
1138 offset without mmap, before the last sync, instead of the
1142 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1143 don't change the mtime of the file, this means the file may
1144 not be backed up (as tdb rounding to block sizes means that
1145 file size changes are quite rare too). The following forces
1146 mtime changes when a transaction completes */
1148 utime(tdb->name, NULL);
1151 /* use a transaction cancel to free memory and remove the
1152 transaction locks */
1153 _tdb1_transaction_cancel(tdb);
1156 return tdb_repack(tdb);
1164 recover from an aborted transaction. Must be called with exclusive
1165 database write access already established (including the open
1166 lock to prevent new processes attaching)
1168 int tdb1_transaction_recover(struct tdb_context *tdb)
1170 tdb1_off_t recovery_head, recovery_eof;
1171 unsigned char *data, *p;
1173 struct tdb1_record rec;
1175 /* find the recovery area */
1176 if (tdb1_ofs_read(tdb, TDB1_RECOVERY_HEAD, &recovery_head) == -1) {
1177 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1178 "tdb1_transaction_recover:"
1179 " failed to read recovery head");
1183 if (recovery_head == 0) {
1184 /* we have never allocated a recovery record */
1188 /* read the recovery record */
1189 if (tdb->tdb1.io->tdb1_read(tdb, recovery_head, &rec,
1190 sizeof(rec), TDB1_DOCONV()) == -1) {
1191 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1192 "tdb1_transaction_recover:"
1193 " failed to read recovery record");
1197 if (rec.magic != TDB1_RECOVERY_MAGIC) {
1198 /* there is no valid recovery data */
1202 if (tdb->flags & TDB_RDONLY) {
1203 tdb->last_error = tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
1204 "tdb1_transaction_recover:"
1205 " attempt to recover read only"
1210 recovery_eof = rec.key_len;
1212 data = (unsigned char *)malloc(rec.data_len);
1214 tdb->last_error = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
1215 "tdb1_transaction_recover:"
1216 " failed to allocate recovery data");
1220 /* read the full recovery data */
1221 if (tdb->tdb1.io->tdb1_read(tdb, recovery_head + sizeof(rec), data,
1222 rec.data_len, 0) == -1) {
1223 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1224 "tdb1_transaction_recover:"
1225 " failed to read recovery data");
1229 /* recover the file data */
1231 while (p+8 < data + rec.data_len) {
1233 if (TDB1_DOCONV()) {
1237 memcpy(&len, p+4, 4);
1239 if (tdb->tdb1.io->tdb1_write(tdb, ofs, p+8, len) == -1) {
1241 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1242 "tdb1_transaction_recover: failed to recover"
1243 " %d bytes at offset %d", len, ofs);
1251 if (transaction1_sync(tdb, 0, tdb->file->map_size) == -1) {
1252 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1253 "tdb1_transaction_recover: failed to sync recovery");
1257 /* if the recovery area is after the recovered eof then remove it */
1258 if (recovery_eof <= recovery_head) {
1259 if (tdb1_ofs_write(tdb, TDB1_RECOVERY_HEAD, &zero) == -1) {
1260 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1261 "tdb1_transaction_recover: failed to remove"
1267 /* remove the recovery magic */
1268 if (tdb1_ofs_write(tdb, recovery_head + offsetof(struct tdb1_record, magic),
1270 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1271 "tdb1_transaction_recover: failed to remove"
1276 if (transaction1_sync(tdb, 0, recovery_eof) == -1) {
1277 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1278 "tdb1_transaction_recover:"
1279 " failed to sync2 recovery");
1283 tdb_logerr(tdb, TDB_SUCCESS, TDB_LOG_WARNING,
1284 "tdb1_transaction_recover: recovered %d byte database",
1291 /* Any I/O failures we say "needs recovery". */
1292 tdb_bool_err tdb1_needs_recovery(struct tdb_context *tdb)
1294 tdb1_off_t recovery_head;
1295 struct tdb1_record rec;
1297 /* find the recovery area */
1298 if (tdb1_ofs_read(tdb, TDB1_RECOVERY_HEAD, &recovery_head) == -1) {
1299 return tdb->last_error;
1302 if (recovery_head == 0) {
1303 /* we have never allocated a recovery record */
1307 /* read the recovery record */
1308 if (tdb->tdb1.io->tdb1_read(tdb, recovery_head, &rec,
1309 sizeof(rec), TDB1_DOCONV()) == -1) {
1310 return tdb->last_error;
1313 return (rec.magic == TDB1_RECOVERY_MAGIC);