2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 2005
8 ** NOTE! The following LGPL license applies to the tdb
9 ** library. This does NOT imply that all of Samba is released
12 This library is free software; you can redistribute it and/or
13 modify it under the terms of the GNU Lesser General Public
14 License as published by the Free Software Foundation; either
15 version 3 of the License, or (at your option) any later version.
17 This library is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 Lesser General Public License for more details.
22 You should have received a copy of the GNU Lesser General Public
23 License along with this library; if not, see <http://www.gnu.org/licenses/>.
26 #include "tdb_private.h"
31 - only allow a single transaction at a time per database. This makes
32 using the transaction API simpler, as otherwise the caller would
33 have to cope with temporary failures in transactions that conflict
34 with other current transactions
36 - keep the transaction recovery information in the same file as the
37 database, using a special 'transaction recovery' record pointed at
38 by the header. This removes the need for extra journal files as
39 used by some other databases
41 - dynamically allocated the transaction recover record, re-using it
42 for subsequent transactions. If a larger record is needed then
43 tdb_free() the old record to place it on the normal tdb freelist
44 before allocating the new record
46 - during transactions, keep a linked list of writes all that have
47 been performed by intercepting all tdb_write() calls. The hooked
48 transaction versions of tdb_read() and tdb_write() check this
49 linked list and try to use the elements of the list in preference
52 - don't allow any locks to be held when a transaction starts,
53 otherwise we can end up with deadlock (plus lack of lock nesting
54 in posix locks would mean the lock is lost)
56 - if the caller gains a lock during the transaction but doesn't
57 release it then fail the commit
59 - allow for nested calls to tdb_transaction_start(), re-using the
60 existing transaction record. If the inner transaction is cancelled
61 then a subsequent commit will fail
63 - keep a mirrored copy of the tdb hash chain heads to allow for the
64 fast hash heads scan on traverse, updating the mirrored copy in
65 the transaction version of tdb_write
67 - allow callers to mix transaction and non-transaction use of tdb,
68 although once a transaction is started then an exclusive lock is
69 gained until the transaction is committed or cancelled
71 - the commit stategy involves first saving away all modified data
72 into a linearised buffer in the transaction recovery area, then
73 marking the transaction recovery area with a magic value to
74 indicate a valid recovery record. In total 4 fsync/msync calls are
75 needed per commit to prevent race conditions. It might be possible
76 to reduce this to 3 or even 2 with some more work.
78 - check for a valid recovery record on open of the tdb, while the
79 global lock is held. Automatically recover from the transaction
80 recovery area if needed, then continue with the open as
81 usual. This allows for smooth crash recovery with no administrator
84 - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
85 still available, but no transaction recovery area is used and no
86 fsync/msync calls are made.
88 - if TDB_NO_NESTING is passed to flags in tdb open then transaction
89 nesting is disabled. tdb_transaction_start() will then implicitely
90 cancel any pending transactions and always start a new transaction
91 context instead of nesting.
97 hold the context of any current transaction
99 struct tdb_transaction {
100 /* we keep a mirrored copy of the tdb hash heads here so
101 tdb_next_hash_chain() can operate efficiently */
102 uint32_t *hash_heads;
104 /* the original io methods - used to do IOs to the real db */
105 const struct tdb_methods *io_methods;
107 /* the list of transaction blocks. When a block is first
108 written to, it gets created in this list */
111 uint32_t block_size; /* bytes in each block */
112 uint32_t last_block_size; /* number of valid bytes in the last block */
114 /* non-zero when an internal transaction error has
115 occurred. All write operations will then fail until the
116 transaction is ended */
117 int transaction_error;
119 /* when inside a transaction we need to keep track of any
120 nested tdb_transaction_start() calls, as these are allowed,
121 but don't create a new transaction */
124 /* set when a prepare has already occurred */
126 tdb_off_t magic_offset;
128 /* old file size before transaction */
129 tdb_len_t old_map_size;
134 read while in a transaction. We need to check first if the data is in our list
135 of transaction elements, then if not do a real read
137 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
138 tdb_len_t len, int cv)
142 /* Only a commit is allowed on a prepared transaction */
143 if (tdb->transaction->prepared) {
144 tdb->ecode = TDB_ERR_EINVAL;
145 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: transaction already prepared, read not allowed\n"));
146 tdb->transaction->transaction_error = 1;
150 /* break it down into block sized ops */
151 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
152 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
153 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
158 buf = (void *)(len2 + (char *)buf);
165 blk = off / tdb->transaction->block_size;
167 /* see if we have it in the block list */
168 if (tdb->transaction->num_blocks <= blk ||
169 tdb->transaction->blocks[blk] == NULL) {
170 /* nope, do a real read */
171 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
177 /* it is in the block list. Now check for the last block */
178 if (blk == tdb->transaction->num_blocks-1) {
179 if (len > tdb->transaction->last_block_size) {
184 /* now copy it out of this block */
185 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
187 tdb_convert(buf, len);
192 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
193 tdb->ecode = TDB_ERR_IO;
194 tdb->transaction->transaction_error = 1;
200 write while in a transaction
202 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
203 const void *buf, tdb_len_t len)
207 /* Only a commit is allowed on a prepared transaction */
208 if (tdb->transaction->prepared) {
209 tdb->ecode = TDB_ERR_EINVAL;
210 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
211 tdb->transaction->transaction_error = 1;
215 /* if the write is to a hash head, then update the transaction
217 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
218 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
219 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
220 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
223 /* break it up into block sized chunks */
224 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
225 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
226 if (transaction_write(tdb, off, buf, len2) != 0) {
232 buf = (const void *)(len2 + (const char *)buf);
240 blk = off / tdb->transaction->block_size;
241 off = off % tdb->transaction->block_size;
243 if (tdb->transaction->num_blocks <= blk) {
244 uint8_t **new_blocks;
245 /* expand the blocks array */
246 if (tdb->transaction->blocks == NULL) {
247 new_blocks = (uint8_t **)malloc(
248 (blk+1)*sizeof(uint8_t *));
250 new_blocks = (uint8_t **)realloc(
251 tdb->transaction->blocks,
252 (blk+1)*sizeof(uint8_t *));
254 if (new_blocks == NULL) {
255 tdb->ecode = TDB_ERR_OOM;
258 memset(&new_blocks[tdb->transaction->num_blocks], 0,
259 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
260 tdb->transaction->blocks = new_blocks;
261 tdb->transaction->num_blocks = blk+1;
262 tdb->transaction->last_block_size = 0;
265 /* allocate and fill a block? */
266 if (tdb->transaction->blocks[blk] == NULL) {
267 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
268 if (tdb->transaction->blocks[blk] == NULL) {
269 tdb->ecode = TDB_ERR_OOM;
270 tdb->transaction->transaction_error = 1;
273 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
274 tdb_len_t len2 = tdb->transaction->block_size;
275 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
276 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
278 if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
279 tdb->transaction->blocks[blk],
281 SAFE_FREE(tdb->transaction->blocks[blk]);
282 tdb->ecode = TDB_ERR_IO;
285 if (blk == tdb->transaction->num_blocks-1) {
286 tdb->transaction->last_block_size = len2;
291 /* overwrite part of an existing block */
293 memset(tdb->transaction->blocks[blk] + off, 0, len);
295 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
297 if (blk == tdb->transaction->num_blocks-1) {
298 if (len + off > tdb->transaction->last_block_size) {
299 tdb->transaction->last_block_size = len + off;
306 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
307 (blk*tdb->transaction->block_size) + off, len));
308 tdb->transaction->transaction_error = 1;
314 write while in a transaction - this varient never expands the transaction blocks, it only
315 updates existing blocks. This means it cannot change the recovery size
317 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
318 const void *buf, tdb_len_t len)
322 /* break it up into block sized chunks */
323 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
324 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
325 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
331 buf = (const void *)(len2 + (const char *)buf);
339 blk = off / tdb->transaction->block_size;
340 off = off % tdb->transaction->block_size;
342 if (tdb->transaction->num_blocks <= blk ||
343 tdb->transaction->blocks[blk] == NULL) {
347 if (blk == tdb->transaction->num_blocks-1 &&
348 off + len > tdb->transaction->last_block_size) {
349 if (off >= tdb->transaction->last_block_size) {
352 len = tdb->transaction->last_block_size - off;
355 /* overwrite part of an existing block */
356 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
363 accelerated hash chain head search, using the cached hash heads
365 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
368 for (;h < tdb->header.hash_size;h++) {
369 /* the +1 takes account of the freelist */
370 if (0 != tdb->transaction->hash_heads[h+1]) {
378 out of bounds check during a transaction
380 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
382 if (len <= tdb->map_size) {
385 return TDB_ERRCODE(TDB_ERR_IO, -1);
389 transaction version of tdb_expand().
391 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
394 /* add a write to the transaction elements, so subsequent
395 reads see the zero data */
396 if (transaction_write(tdb, size, NULL, addition) != 0) {
404 brlock during a transaction - ignore them
406 static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset,
407 int rw_type, int lck_type, int probe, size_t len)
412 static const struct tdb_methods transaction_methods = {
415 transaction_next_hash_chain,
417 transaction_expand_file,
424 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
426 if (tdb->flags & TDB_NOSYNC) {
430 if (fsync(tdb->fd) != 0) {
431 tdb->ecode = TDB_ERR_IO;
432 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
437 tdb_off_t moffset = offset & ~(tdb->page_size-1);
438 if (msync(moffset + (char *)tdb->map_ptr,
439 length + (offset - moffset), MS_SYNC) != 0) {
440 tdb->ecode = TDB_ERR_IO;
441 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
450 int tdb_transaction_cancel_internal(struct tdb_context *tdb)
454 if (tdb->transaction == NULL) {
455 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
459 if (tdb->transaction->nesting != 0) {
460 tdb->transaction->transaction_error = 1;
461 tdb->transaction->nesting--;
465 tdb->map_size = tdb->transaction->old_map_size;
467 /* free all the transaction blocks */
468 for (i=0;i<tdb->transaction->num_blocks;i++) {
469 if (tdb->transaction->blocks[i] != NULL) {
470 free(tdb->transaction->blocks[i]);
473 SAFE_FREE(tdb->transaction->blocks);
475 if (tdb->transaction->magic_offset) {
476 const struct tdb_methods *methods = tdb->transaction->io_methods;
479 /* remove the recovery marker */
480 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 4) == -1 ||
481 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
482 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
487 /* remove any global lock created during the transaction */
488 if (tdb->global_lock.count != 0) {
489 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size);
490 tdb->global_lock.count = 0;
493 /* remove any locks created during the transaction */
494 if (tdb->num_locks != 0) {
495 for (i=0;i<tdb->num_lockrecs;i++) {
496 tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
497 F_UNLCK,F_SETLKW, 0, 1);
500 tdb->num_lockrecs = 0;
501 SAFE_FREE(tdb->lockrecs);
504 /* restore the normal io methods */
505 tdb->methods = tdb->transaction->io_methods;
507 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
508 tdb_transaction_unlock(tdb);
509 SAFE_FREE(tdb->transaction->hash_heads);
510 SAFE_FREE(tdb->transaction);
516 start a tdb transaction. No token is returned, as only a single
517 transaction is allowed to be pending per tdb_context
519 int tdb_transaction_start(struct tdb_context *tdb)
521 /* some sanity checks */
522 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
523 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
524 tdb->ecode = TDB_ERR_EINVAL;
528 /* cope with nested tdb_transaction_start() calls */
529 if (tdb->transaction != NULL) {
530 tdb_trace(tdb, "tdb_transaction_start");
531 if (!tdb->flags & TDB_NO_NESTING) {
532 tdb->transaction->nesting++;
533 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
534 tdb->transaction->nesting));
537 tdb_transaction_cancel_internal(tdb);
538 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: cancelling previous transaction\n"));
542 if (tdb->num_locks != 0 || tdb->global_lock.count) {
543 /* the caller must not have any locks when starting a
544 transaction as otherwise we'll be screwed by lack
545 of nested locks in posix */
546 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
547 tdb->ecode = TDB_ERR_LOCK;
551 if (tdb->travlocks.next != NULL) {
552 /* you cannot use transactions inside a traverse (although you can use
553 traverse inside a transaction) as otherwise you can end up with
555 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
556 tdb->ecode = TDB_ERR_LOCK;
560 tdb->transaction = (struct tdb_transaction *)
561 calloc(sizeof(struct tdb_transaction), 1);
562 if (tdb->transaction == NULL) {
563 tdb->ecode = TDB_ERR_OOM;
567 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
568 tdb->transaction->block_size = tdb->page_size;
570 /* get the transaction write lock. This is a blocking lock. As
571 discussed with Volker, there are a number of ways we could
572 make this async, which we will probably do in the future */
573 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
574 SAFE_FREE(tdb->transaction->blocks);
575 SAFE_FREE(tdb->transaction);
579 /* get a read lock from the freelist to the end of file. This
580 is upgraded to a write lock during the commit */
581 if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) {
582 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
583 tdb->ecode = TDB_ERR_LOCK;
587 /* setup a copy of the hash table heads so the hash scan in
588 traverse can be fast */
589 tdb->transaction->hash_heads = (uint32_t *)
590 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
591 if (tdb->transaction->hash_heads == NULL) {
592 tdb->ecode = TDB_ERR_OOM;
595 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
596 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
597 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
598 tdb->ecode = TDB_ERR_IO;
602 /* make sure we know about any file expansions already done by
604 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
605 tdb->transaction->old_map_size = tdb->map_size;
607 /* finally hook the io methods, replacing them with
608 transaction specific methods */
609 tdb->transaction->io_methods = tdb->methods;
610 tdb->methods = &transaction_methods;
612 /* Trace at the end, so we get sequence number correct. */
613 tdb_trace(tdb, "tdb_transaction_start");
617 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
618 tdb_transaction_unlock(tdb);
619 SAFE_FREE(tdb->transaction->blocks);
620 SAFE_FREE(tdb->transaction->hash_heads);
621 SAFE_FREE(tdb->transaction);
627 cancel the current transaction
629 int tdb_transaction_cancel(struct tdb_context *tdb)
631 tdb_trace(tdb, "tdb_transaction_cancel");
632 return tdb_transaction_cancel_internal(tdb);
636 work out how much space the linearised recovery data will consume
638 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
640 tdb_len_t recovery_size = 0;
643 recovery_size = sizeof(uint32_t);
644 for (i=0;i<tdb->transaction->num_blocks;i++) {
645 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
648 if (tdb->transaction->blocks[i] == NULL) {
651 recovery_size += 2*sizeof(tdb_off_t);
652 if (i == tdb->transaction->num_blocks-1) {
653 recovery_size += tdb->transaction->last_block_size;
655 recovery_size += tdb->transaction->block_size;
659 return recovery_size;
663 allocate the recovery area, or use an existing recovery area if it is
666 static int tdb_recovery_allocate(struct tdb_context *tdb,
667 tdb_len_t *recovery_size,
668 tdb_off_t *recovery_offset,
669 tdb_len_t *recovery_max_size)
671 struct list_struct rec;
672 const struct tdb_methods *methods = tdb->transaction->io_methods;
673 tdb_off_t recovery_head;
675 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
676 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
682 if (recovery_head != 0 &&
683 methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
684 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
688 *recovery_size = tdb_recovery_size(tdb);
690 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
691 /* it fits in the existing area */
692 *recovery_max_size = rec.rec_len;
693 *recovery_offset = recovery_head;
697 /* we need to free up the old recovery area, then allocate a
698 new one at the end of the file. Note that we cannot use
699 tdb_allocate() to allocate the new one as that might return
700 us an area that is being currently used (as of the start of
702 if (recovery_head != 0) {
703 if (tdb_free(tdb, recovery_head, &rec) == -1) {
704 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
709 /* the tdb_free() call might have increased the recovery size */
710 *recovery_size = tdb_recovery_size(tdb);
712 /* round up to a multiple of page size */
713 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
714 *recovery_offset = tdb->map_size;
715 recovery_head = *recovery_offset;
717 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
718 (tdb->map_size - tdb->transaction->old_map_size) +
719 sizeof(rec) + *recovery_max_size) == -1) {
720 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
724 /* remap the file (if using mmap) */
725 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
727 /* we have to reset the old map size so that we don't try to expand the file
728 again in the transaction commit, which would destroy the recovery area */
729 tdb->transaction->old_map_size = tdb->map_size;
731 /* write the recovery header offset and sync - we can sync without a race here
732 as the magic ptr in the recovery record has not been set */
733 CONVERT(recovery_head);
734 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
735 &recovery_head, sizeof(tdb_off_t)) == -1) {
736 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
739 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
740 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
749 setup the recovery data that will be used on a crash during commit
751 static int transaction_setup_recovery(struct tdb_context *tdb,
752 tdb_off_t *magic_offset)
754 tdb_len_t recovery_size;
755 unsigned char *data, *p;
756 const struct tdb_methods *methods = tdb->transaction->io_methods;
757 struct list_struct *rec;
758 tdb_off_t recovery_offset, recovery_max_size;
759 tdb_off_t old_map_size = tdb->transaction->old_map_size;
760 uint32_t magic, tailer;
764 check that the recovery area has enough space
766 if (tdb_recovery_allocate(tdb, &recovery_size,
767 &recovery_offset, &recovery_max_size) == -1) {
771 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
773 tdb->ecode = TDB_ERR_OOM;
777 rec = (struct list_struct *)data;
778 memset(rec, 0, sizeof(*rec));
781 rec->data_len = recovery_size;
782 rec->rec_len = recovery_max_size;
783 rec->key_len = old_map_size;
786 /* build the recovery data into a single blob to allow us to do a single
787 large write, which should be more efficient */
788 p = data + sizeof(*rec);
789 for (i=0;i<tdb->transaction->num_blocks;i++) {
793 if (tdb->transaction->blocks[i] == NULL) {
797 offset = i * tdb->transaction->block_size;
798 length = tdb->transaction->block_size;
799 if (i == tdb->transaction->num_blocks-1) {
800 length = tdb->transaction->last_block_size;
803 if (offset >= old_map_size) {
806 if (offset + length > tdb->transaction->old_map_size) {
807 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
809 tdb->ecode = TDB_ERR_CORRUPT;
812 memcpy(p, &offset, 4);
813 memcpy(p+4, &length, 4);
817 /* the recovery area contains the old data, not the
818 new data, so we have to call the original tdb_read
820 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
822 tdb->ecode = TDB_ERR_IO;
829 tailer = sizeof(*rec) + recovery_max_size;
830 memcpy(p, &tailer, 4);
833 /* write the recovery data to the recovery area */
834 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
835 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
837 tdb->ecode = TDB_ERR_IO;
840 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
841 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
843 tdb->ecode = TDB_ERR_IO;
847 /* as we don't have ordered writes, we have to sync the recovery
848 data before we update the magic to indicate that the recovery
850 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
857 magic = TDB_RECOVERY_MAGIC;
860 *magic_offset = recovery_offset + offsetof(struct list_struct, magic);
862 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
863 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
864 tdb->ecode = TDB_ERR_IO;
867 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
868 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
869 tdb->ecode = TDB_ERR_IO;
873 /* ensure the recovery magic marker is on disk */
874 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
881 static int tdb_transaction_prepare_commit_internal(struct tdb_context *tdb)
883 const struct tdb_methods *methods;
885 if (tdb->transaction == NULL) {
886 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
890 if (tdb->transaction->prepared) {
891 tdb->ecode = TDB_ERR_EINVAL;
892 tdb_transaction_cancel(tdb);
893 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
897 if (tdb->transaction->transaction_error) {
898 tdb->ecode = TDB_ERR_IO;
899 tdb_transaction_cancel_internal(tdb);
900 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
905 if (tdb->transaction->nesting != 0) {
906 tdb->transaction->nesting--;
911 /* store seqnum now, before reading becomes illegal. */
912 tdb_ofs_read(tdb, TDB_SEQNUM_OFS, &tdb->transaction_prepare_seqnum);
915 /* check for a null transaction */
916 if (tdb->transaction->blocks == NULL) {
920 methods = tdb->transaction->io_methods;
922 /* if there are any locks pending then the caller has not
923 nested their locks properly, so fail the transaction */
924 if (tdb->num_locks || tdb->global_lock.count) {
925 tdb->ecode = TDB_ERR_LOCK;
926 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
927 tdb_transaction_cancel_internal(tdb);
931 /* upgrade the main transaction lock region to a write lock */
932 if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
933 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
934 tdb->ecode = TDB_ERR_LOCK;
935 tdb_transaction_cancel_internal(tdb);
939 /* get the global lock - this prevents new users attaching to the database
941 if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
942 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
943 tdb->ecode = TDB_ERR_LOCK;
944 tdb_transaction_cancel_internal(tdb);
948 if (!(tdb->flags & TDB_NOSYNC)) {
949 /* write the recovery data to the end of the file */
950 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
951 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
952 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
953 tdb_transaction_cancel_internal(tdb);
958 tdb->transaction->prepared = true;
960 /* expand the file to the new size if needed */
961 if (tdb->map_size != tdb->transaction->old_map_size) {
962 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
964 tdb->transaction->old_map_size) == -1) {
965 tdb->ecode = TDB_ERR_IO;
966 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
967 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
968 tdb_transaction_cancel_internal(tdb);
971 tdb->map_size = tdb->transaction->old_map_size;
972 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
975 /* Keep the global lock until the actual commit */
981 prepare to commit the current transaction
983 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
985 tdb_trace(tdb, "tdb_transaction_prepare_commit");
986 return tdb_transaction_prepare_commit_internal(tdb);
990 commit the current transaction
992 int tdb_transaction_commit(struct tdb_context *tdb)
994 const struct tdb_methods *methods;
997 if (tdb->transaction == NULL) {
998 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
1002 /* If we've prepared, can't read seqnum. */
1003 if (tdb->transaction->prepared) {
1004 tdb_trace_seqnum(tdb, tdb->transaction_prepare_seqnum,
1005 "tdb_transaction_commit");
1007 tdb_trace(tdb, "tdb_transaction_commit");
1010 if (tdb->transaction->transaction_error) {
1011 tdb->ecode = TDB_ERR_IO;
1012 tdb_transaction_cancel(tdb);
1013 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1018 if (tdb->transaction->nesting != 0) {
1019 tdb->transaction->nesting--;
1023 /* check for a null transaction */
1024 if (tdb->transaction->blocks == NULL) {
1025 tdb_transaction_cancel_internal(tdb);
1029 if (!tdb->transaction->prepared) {
1030 int ret = tdb_transaction_prepare_commit_internal(tdb);
1035 methods = tdb->transaction->io_methods;
1037 /* perform all the writes */
1038 for (i=0;i<tdb->transaction->num_blocks;i++) {
1042 if (tdb->transaction->blocks[i] == NULL) {
1046 offset = i * tdb->transaction->block_size;
1047 length = tdb->transaction->block_size;
1048 if (i == tdb->transaction->num_blocks-1) {
1049 length = tdb->transaction->last_block_size;
1052 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1053 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1055 /* we've overwritten part of the data and
1056 possibly expanded the file, so we need to
1057 run the crash recovery code */
1058 tdb->methods = methods;
1059 tdb_transaction_recover(tdb);
1061 tdb_transaction_cancel_internal(tdb);
1062 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1064 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1067 SAFE_FREE(tdb->transaction->blocks[i]);
1070 SAFE_FREE(tdb->transaction->blocks);
1071 tdb->transaction->num_blocks = 0;
1073 /* ensure the new data is on disk */
1074 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1078 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1081 TODO: maybe write to some dummy hdr field, or write to magic
1082 offset without mmap, before the last sync, instead of the
1086 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1087 don't change the mtime of the file, this means the file may
1088 not be backed up (as tdb rounding to block sizes means that
1089 file size changes are quite rare too). The following forces
1090 mtime changes when a transaction completes */
1092 utime(tdb->name, NULL);
1095 /* use a transaction cancel to free memory and remove the
1096 transaction locks */
1097 tdb_transaction_cancel_internal(tdb);
1104 recover from an aborted transaction. Must be called with exclusive
1105 database write access already established (including the global
1106 lock to prevent new processes attaching)
1108 int tdb_transaction_recover(struct tdb_context *tdb)
1110 tdb_off_t recovery_head, recovery_eof;
1111 unsigned char *data, *p;
1113 struct list_struct rec;
1115 /* find the recovery area */
1116 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1117 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1118 tdb->ecode = TDB_ERR_IO;
1122 if (recovery_head == 0) {
1123 /* we have never allocated a recovery record */
1127 /* read the recovery record */
1128 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1129 sizeof(rec), DOCONV()) == -1) {
1130 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1131 tdb->ecode = TDB_ERR_IO;
1135 if (rec.magic != TDB_RECOVERY_MAGIC) {
1136 /* there is no valid recovery data */
1140 if (tdb->read_only) {
1141 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1142 tdb->ecode = TDB_ERR_CORRUPT;
1146 recovery_eof = rec.key_len;
1148 data = (unsigned char *)malloc(rec.data_len);
1150 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1151 tdb->ecode = TDB_ERR_OOM;
1155 /* read the full recovery data */
1156 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1157 rec.data_len, 0) == -1) {
1158 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1159 tdb->ecode = TDB_ERR_IO;
1163 /* recover the file data */
1165 while (p+8 < data + rec.data_len) {
1171 memcpy(&len, p+4, 4);
1173 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1175 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1176 tdb->ecode = TDB_ERR_IO;
1184 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1185 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1186 tdb->ecode = TDB_ERR_IO;
1190 /* if the recovery area is after the recovered eof then remove it */
1191 if (recovery_eof <= recovery_head) {
1192 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1193 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1194 tdb->ecode = TDB_ERR_IO;
1199 /* remove the recovery magic */
1200 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic),
1202 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1203 tdb->ecode = TDB_ERR_IO;
1207 /* reduce the file size to the old size */
1209 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1210 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1211 tdb->ecode = TDB_ERR_IO;
1214 tdb->map_size = recovery_eof;
1217 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1218 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1219 tdb->ecode = TDB_ERR_IO;
1223 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",