2 Unix SMB/CIFS implementation.
4 trivial database library
6 Copyright (C) Andrew Tridgell 2005
8 ** NOTE! The following LGPL license applies to the tdb
9 ** library. This does NOT imply that all of Samba is released
12 This library is free software; you can redistribute it and/or
13 modify it under the terms of the GNU Lesser General Public
14 License as published by the Free Software Foundation; either
15 version 3 of the License, or (at your option) any later version.
17 This library is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 Lesser General Public License for more details.
22 You should have received a copy of the GNU Lesser General Public
23 License along with this library; if not, see <http://www.gnu.org/licenses/>.
26 #include "tdb_private.h"
31 - only allow a single transaction at a time per database. This makes
32 using the transaction API simpler, as otherwise the caller would
33 have to cope with temporary failures in transactions that conflict
34 with other current transactions
36 - keep the transaction recovery information in the same file as the
37 database, using a special 'transaction recovery' record pointed at
38 by the header. This removes the need for extra journal files as
39 used by some other databases
41 - dynamically allocated the transaction recover record, re-using it
42 for subsequent transactions. If a larger record is needed then
43 tdb_free() the old record to place it on the normal tdb freelist
44 before allocating the new record
46 - during transactions, keep a linked list of writes all that have
47 been performed by intercepting all tdb_write() calls. The hooked
48 transaction versions of tdb_read() and tdb_write() check this
49 linked list and try to use the elements of the list in preference
52 - don't allow any locks to be held when a transaction starts,
53 otherwise we can end up with deadlock (plus lack of lock nesting
54 in posix locks would mean the lock is lost)
56 - if the caller gains a lock during the transaction but doesn't
57 release it then fail the commit
59 - allow for nested calls to tdb_transaction_start(), re-using the
60 existing transaction record. If the inner transaction is cancelled
61 then a subsequent commit will fail
63 - keep a mirrored copy of the tdb hash chain heads to allow for the
64 fast hash heads scan on traverse, updating the mirrored copy in
65 the transaction version of tdb_write
67 - allow callers to mix transaction and non-transaction use of tdb,
68 although once a transaction is started then an exclusive lock is
69 gained until the transaction is committed or cancelled
71 - the commit stategy involves first saving away all modified data
72 into a linearised buffer in the transaction recovery area, then
73 marking the transaction recovery area with a magic value to
74 indicate a valid recovery record. In total 4 fsync/msync calls are
75 needed per commit to prevent race conditions. It might be possible
76 to reduce this to 3 or even 2 with some more work.
78 - check for a valid recovery record on open of the tdb, while the
79 open lock is held. Automatically recover from the transaction
80 recovery area if needed, then continue with the open as
81 usual. This allows for smooth crash recovery with no administrator
84 - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
85 still available, but no transaction recovery area is used and no
86 fsync/msync calls are made.
88 - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
89 tdb_add_flags() transaction nesting is enabled.
90 It resets the TDB_DISALLOW_NESTING flag, as both cannot be used together.
91 The default is that transaction nesting is allowed.
92 Note: this default may change in future versions of tdb.
94 Beware. when transactions are nested a transaction successfully
95 completed with tdb_transaction_commit() can be silently unrolled later.
97 - if TDB_DISALLOW_NESTING is passed to flags in tdb open, or added using
98 tdb_add_flags() transaction nesting is disabled.
99 It resets the TDB_ALLOW_NESTING flag, as both cannot be used together.
100 An attempt create a nested transaction will fail with TDB_ERR_NESTING.
101 The default is that transaction nesting is allowed.
102 Note: this default may change in future versions of tdb.
107 hold the context of any current transaction
109 struct tdb_transaction {
110 /* we keep a mirrored copy of the tdb hash heads here so
111 tdb_next_hash_chain() can operate efficiently */
112 uint32_t *hash_heads;
114 /* the original io methods - used to do IOs to the real db */
115 const struct tdb_methods *io_methods;
117 /* the list of transaction blocks. When a block is first
118 written to, it gets created in this list */
121 uint32_t block_size; /* bytes in each block */
122 uint32_t last_block_size; /* number of valid bytes in the last block */
124 /* non-zero when an internal transaction error has
125 occurred. All write operations will then fail until the
126 transaction is ended */
127 int transaction_error;
129 /* when inside a transaction we need to keep track of any
130 nested tdb_transaction_start() calls, as these are allowed,
131 but don't create a new transaction */
134 /* set when a prepare has already occurred */
136 tdb_off_t magic_offset;
138 /* old file size before transaction */
139 tdb_len_t old_map_size;
141 /* we should re-pack on commit */
147 read while in a transaction. We need to check first if the data is in our list
148 of transaction elements, then if not do a real read
150 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
151 tdb_len_t len, int cv)
155 /* break it down into block sized ops */
156 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
157 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
158 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
163 buf = (void *)(len2 + (char *)buf);
170 blk = off / tdb->transaction->block_size;
172 /* see if we have it in the block list */
173 if (tdb->transaction->num_blocks <= blk ||
174 tdb->transaction->blocks[blk] == NULL) {
175 /* nope, do a real read */
176 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
182 /* it is in the block list. Now check for the last block */
183 if (blk == tdb->transaction->num_blocks-1) {
184 if (len > tdb->transaction->last_block_size) {
189 /* now copy it out of this block */
190 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
192 tdb_convert(buf, len);
197 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
198 tdb->ecode = TDB_ERR_IO;
199 tdb->transaction->transaction_error = 1;
205 write while in a transaction
207 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
208 const void *buf, tdb_len_t len)
212 /* Only a commit is allowed on a prepared transaction */
213 if (tdb->transaction->prepared) {
214 tdb->ecode = TDB_ERR_EINVAL;
215 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
216 tdb->transaction->transaction_error = 1;
220 /* if the write is to a hash head, then update the transaction
222 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
223 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
224 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
225 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
228 /* break it up into block sized chunks */
229 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
230 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
231 if (transaction_write(tdb, off, buf, len2) != 0) {
237 buf = (const void *)(len2 + (const char *)buf);
245 blk = off / tdb->transaction->block_size;
246 off = off % tdb->transaction->block_size;
248 if (tdb->transaction->num_blocks <= blk) {
249 uint8_t **new_blocks;
250 /* expand the blocks array */
251 if (tdb->transaction->blocks == NULL) {
252 new_blocks = (uint8_t **)malloc(
253 (blk+1)*sizeof(uint8_t *));
255 new_blocks = (uint8_t **)realloc(
256 tdb->transaction->blocks,
257 (blk+1)*sizeof(uint8_t *));
259 if (new_blocks == NULL) {
260 tdb->ecode = TDB_ERR_OOM;
263 memset(&new_blocks[tdb->transaction->num_blocks], 0,
264 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
265 tdb->transaction->blocks = new_blocks;
266 tdb->transaction->num_blocks = blk+1;
267 tdb->transaction->last_block_size = 0;
270 /* allocate and fill a block? */
271 if (tdb->transaction->blocks[blk] == NULL) {
272 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
273 if (tdb->transaction->blocks[blk] == NULL) {
274 tdb->ecode = TDB_ERR_OOM;
275 tdb->transaction->transaction_error = 1;
278 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
279 tdb_len_t len2 = tdb->transaction->block_size;
280 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
281 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
283 if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
284 tdb->transaction->blocks[blk],
286 SAFE_FREE(tdb->transaction->blocks[blk]);
287 tdb->ecode = TDB_ERR_IO;
290 if (blk == tdb->transaction->num_blocks-1) {
291 tdb->transaction->last_block_size = len2;
296 /* overwrite part of an existing block */
298 memset(tdb->transaction->blocks[blk] + off, 0, len);
300 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
302 if (blk == tdb->transaction->num_blocks-1) {
303 if (len + off > tdb->transaction->last_block_size) {
304 tdb->transaction->last_block_size = len + off;
311 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
312 (blk*tdb->transaction->block_size) + off, len));
313 tdb->transaction->transaction_error = 1;
319 write while in a transaction - this varient never expands the transaction blocks, it only
320 updates existing blocks. This means it cannot change the recovery size
322 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
323 const void *buf, tdb_len_t len)
327 /* break it up into block sized chunks */
328 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
329 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
330 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
336 buf = (const void *)(len2 + (const char *)buf);
344 blk = off / tdb->transaction->block_size;
345 off = off % tdb->transaction->block_size;
347 if (tdb->transaction->num_blocks <= blk ||
348 tdb->transaction->blocks[blk] == NULL) {
352 if (blk == tdb->transaction->num_blocks-1 &&
353 off + len > tdb->transaction->last_block_size) {
354 if (off >= tdb->transaction->last_block_size) {
357 len = tdb->transaction->last_block_size - off;
360 /* overwrite part of an existing block */
361 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
368 accelerated hash chain head search, using the cached hash heads
370 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
373 for (;h < tdb->header.hash_size;h++) {
374 /* the +1 takes account of the freelist */
375 if (0 != tdb->transaction->hash_heads[h+1]) {
383 out of bounds check during a transaction
385 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
387 if (len <= tdb->map_size) {
390 tdb->ecode = TDB_ERR_IO;
395 transaction version of tdb_expand().
397 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
400 /* add a write to the transaction elements, so subsequent
401 reads see the zero data */
402 if (transaction_write(tdb, size, NULL, addition) != 0) {
406 tdb->transaction->need_repack = true;
412 brlock during a transaction - ignore them
414 static int transaction_brlock(struct tdb_context *tdb,
415 int rw_type, tdb_off_t offset, size_t len,
416 enum tdb_lock_flags flags)
418 /* FIXME: We actually grab the open lock during a transaction. */
419 if (offset == OPEN_LOCK)
420 return tdb_brlock(tdb, rw_type, offset, len, flags);
424 static int transaction_brunlock(struct tdb_context *tdb,
425 int rw_type, tdb_off_t offset, size_t len)
430 static const struct tdb_methods transaction_methods = {
433 transaction_next_hash_chain,
435 transaction_expand_file,
442 start a tdb transaction. No token is returned, as only a single
443 transaction is allowed to be pending per tdb_context
445 int tdb_transaction_start(struct tdb_context *tdb)
447 /* some sanity checks */
448 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
449 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
450 tdb->ecode = TDB_ERR_EINVAL;
454 /* cope with nested tdb_transaction_start() calls */
455 if (tdb->transaction != NULL) {
456 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
457 tdb->ecode = TDB_ERR_NESTING;
460 tdb->transaction->nesting++;
461 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
462 tdb->transaction->nesting));
466 if (tdb_have_extra_locks(tdb)) {
467 /* the caller must not have any locks when starting a
468 transaction as otherwise we'll be screwed by lack
469 of nested locks in posix */
470 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
471 tdb->ecode = TDB_ERR_LOCK;
475 if (tdb->travlocks.next != NULL) {
476 /* you cannot use transactions inside a traverse (although you can use
477 traverse inside a transaction) as otherwise you can end up with
479 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
480 tdb->ecode = TDB_ERR_LOCK;
484 tdb->transaction = (struct tdb_transaction *)
485 calloc(sizeof(struct tdb_transaction), 1);
486 if (tdb->transaction == NULL) {
487 tdb->ecode = TDB_ERR_OOM;
491 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
492 tdb->transaction->block_size = tdb->page_size;
494 /* get the transaction write lock. This is a blocking lock. As
495 discussed with Volker, there are a number of ways we could
496 make this async, which we will probably do in the future */
497 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
498 SAFE_FREE(tdb->transaction->blocks);
499 SAFE_FREE(tdb->transaction);
503 /* get a read lock from the freelist to the end of file. This
504 is upgraded to a write lock during the commit */
505 if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
506 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
507 goto fail_allrecord_lock;
510 /* setup a copy of the hash table heads so the hash scan in
511 traverse can be fast */
512 tdb->transaction->hash_heads = (uint32_t *)
513 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
514 if (tdb->transaction->hash_heads == NULL) {
515 tdb->ecode = TDB_ERR_OOM;
518 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
519 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
520 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
521 tdb->ecode = TDB_ERR_IO;
525 /* make sure we know about any file expansions already done by
527 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
528 tdb->transaction->old_map_size = tdb->map_size;
530 /* finally hook the io methods, replacing them with
531 transaction specific methods */
532 tdb->transaction->io_methods = tdb->methods;
533 tdb->methods = &transaction_methods;
535 /* Trace at the end, so we get sequence number correct. */
536 tdb_trace(tdb, "tdb_transaction_start");
540 tdb_allrecord_unlock(tdb, F_RDLCK, false);
542 tdb_transaction_unlock(tdb, F_WRLCK);
543 SAFE_FREE(tdb->transaction->blocks);
544 SAFE_FREE(tdb->transaction->hash_heads);
545 SAFE_FREE(tdb->transaction);
553 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
555 if (tdb->flags & TDB_NOSYNC) {
559 if (fdatasync(tdb->fd) != 0) {
560 tdb->ecode = TDB_ERR_IO;
561 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
566 tdb_off_t moffset = offset & ~(tdb->page_size-1);
567 if (msync(moffset + (char *)tdb->map_ptr,
568 length + (offset - moffset), MS_SYNC) != 0) {
569 tdb->ecode = TDB_ERR_IO;
570 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
580 static int _tdb_transaction_cancel(struct tdb_context *tdb)
584 if (tdb->transaction == NULL) {
585 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
589 if (tdb->transaction->nesting != 0) {
590 tdb->transaction->transaction_error = 1;
591 tdb->transaction->nesting--;
595 tdb->map_size = tdb->transaction->old_map_size;
597 /* free all the transaction blocks */
598 for (i=0;i<tdb->transaction->num_blocks;i++) {
599 if (tdb->transaction->blocks[i] != NULL) {
600 free(tdb->transaction->blocks[i]);
603 SAFE_FREE(tdb->transaction->blocks);
605 if (tdb->transaction->magic_offset) {
606 const struct tdb_methods *methods = tdb->transaction->io_methods;
607 const uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
609 /* remove the recovery marker */
610 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
611 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
612 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
617 /* This also removes the OPEN_LOCK, if we have it. */
618 tdb_release_transaction_locks(tdb);
620 /* restore the normal io methods */
621 tdb->methods = tdb->transaction->io_methods;
623 SAFE_FREE(tdb->transaction->hash_heads);
624 SAFE_FREE(tdb->transaction);
630 cancel the current transaction
632 int tdb_transaction_cancel(struct tdb_context *tdb)
634 tdb_trace(tdb, "tdb_transaction_cancel");
635 return _tdb_transaction_cancel(tdb);
639 work out how much space the linearised recovery data will consume
641 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
643 tdb_len_t recovery_size = 0;
646 recovery_size = sizeof(uint32_t);
647 for (i=0;i<tdb->transaction->num_blocks;i++) {
648 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
651 if (tdb->transaction->blocks[i] == NULL) {
654 recovery_size += 2*sizeof(tdb_off_t);
655 if (i == tdb->transaction->num_blocks-1) {
656 recovery_size += tdb->transaction->last_block_size;
658 recovery_size += tdb->transaction->block_size;
662 return recovery_size;
666 allocate the recovery area, or use an existing recovery area if it is
669 static int tdb_recovery_allocate(struct tdb_context *tdb,
670 tdb_len_t *recovery_size,
671 tdb_off_t *recovery_offset,
672 tdb_len_t *recovery_max_size)
674 struct tdb_record rec;
675 const struct tdb_methods *methods = tdb->transaction->io_methods;
676 tdb_off_t recovery_head;
678 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
679 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
685 if (recovery_head != 0) {
686 if (methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
687 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
690 /* ignore invalid recovery regions: can happen in crash */
691 if (rec.magic != TDB_RECOVERY_MAGIC &&
692 rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
697 *recovery_size = tdb_recovery_size(tdb);
699 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
700 /* it fits in the existing area */
701 *recovery_max_size = rec.rec_len;
702 *recovery_offset = recovery_head;
706 /* we need to free up the old recovery area, then allocate a
707 new one at the end of the file. Note that we cannot use
708 tdb_allocate() to allocate the new one as that might return
709 us an area that is being currently used (as of the start of
711 if (recovery_head != 0) {
712 if (tdb_free(tdb, recovery_head, &rec) == -1) {
713 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
718 /* the tdb_free() call might have increased the recovery size */
719 *recovery_size = tdb_recovery_size(tdb);
721 /* round up to a multiple of page size */
722 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
723 *recovery_offset = tdb->map_size;
724 recovery_head = *recovery_offset;
726 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
727 (tdb->map_size - tdb->transaction->old_map_size) +
728 sizeof(rec) + *recovery_max_size) == -1) {
729 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
733 /* remap the file (if using mmap) */
734 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
736 /* we have to reset the old map size so that we don't try to expand the file
737 again in the transaction commit, which would destroy the recovery area */
738 tdb->transaction->old_map_size = tdb->map_size;
740 /* write the recovery header offset and sync - we can sync without a race here
741 as the magic ptr in the recovery record has not been set */
742 CONVERT(recovery_head);
743 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
744 &recovery_head, sizeof(tdb_off_t)) == -1) {
745 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
748 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
749 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
758 setup the recovery data that will be used on a crash during commit
760 static int transaction_setup_recovery(struct tdb_context *tdb,
761 tdb_off_t *magic_offset)
763 tdb_len_t recovery_size;
764 unsigned char *data, *p;
765 const struct tdb_methods *methods = tdb->transaction->io_methods;
766 struct tdb_record *rec;
767 tdb_off_t recovery_offset, recovery_max_size;
768 tdb_off_t old_map_size = tdb->transaction->old_map_size;
769 uint32_t magic, tailer;
773 check that the recovery area has enough space
775 if (tdb_recovery_allocate(tdb, &recovery_size,
776 &recovery_offset, &recovery_max_size) == -1) {
780 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
782 tdb->ecode = TDB_ERR_OOM;
786 rec = (struct tdb_record *)data;
787 memset(rec, 0, sizeof(*rec));
789 rec->magic = TDB_RECOVERY_INVALID_MAGIC;
790 rec->data_len = recovery_size;
791 rec->rec_len = recovery_max_size;
792 rec->key_len = old_map_size;
795 /* build the recovery data into a single blob to allow us to do a single
796 large write, which should be more efficient */
797 p = data + sizeof(*rec);
798 for (i=0;i<tdb->transaction->num_blocks;i++) {
802 if (tdb->transaction->blocks[i] == NULL) {
806 offset = i * tdb->transaction->block_size;
807 length = tdb->transaction->block_size;
808 if (i == tdb->transaction->num_blocks-1) {
809 length = tdb->transaction->last_block_size;
812 if (offset >= old_map_size) {
815 if (offset + length > tdb->transaction->old_map_size) {
816 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
818 tdb->ecode = TDB_ERR_CORRUPT;
821 memcpy(p, &offset, 4);
822 memcpy(p+4, &length, 4);
826 /* the recovery area contains the old data, not the
827 new data, so we have to call the original tdb_read
829 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
831 tdb->ecode = TDB_ERR_IO;
838 tailer = sizeof(*rec) + recovery_max_size;
839 memcpy(p, &tailer, 4);
842 /* write the recovery data to the recovery area */
843 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
844 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
846 tdb->ecode = TDB_ERR_IO;
849 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
850 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
852 tdb->ecode = TDB_ERR_IO;
856 /* as we don't have ordered writes, we have to sync the recovery
857 data before we update the magic to indicate that the recovery
859 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
866 magic = TDB_RECOVERY_MAGIC;
869 *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
871 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
872 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
873 tdb->ecode = TDB_ERR_IO;
876 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
877 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
878 tdb->ecode = TDB_ERR_IO;
882 /* ensure the recovery magic marker is on disk */
883 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
890 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
892 const struct tdb_methods *methods;
894 if (tdb->transaction == NULL) {
895 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
899 if (tdb->transaction->prepared) {
900 tdb->ecode = TDB_ERR_EINVAL;
901 _tdb_transaction_cancel(tdb);
902 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
906 if (tdb->transaction->transaction_error) {
907 tdb->ecode = TDB_ERR_IO;
908 _tdb_transaction_cancel(tdb);
909 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
914 if (tdb->transaction->nesting != 0) {
918 /* check for a null transaction */
919 if (tdb->transaction->blocks == NULL) {
923 methods = tdb->transaction->io_methods;
925 /* if there are any locks pending then the caller has not
926 nested their locks properly, so fail the transaction */
927 if (tdb_have_extra_locks(tdb)) {
928 tdb->ecode = TDB_ERR_LOCK;
929 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
930 _tdb_transaction_cancel(tdb);
934 /* upgrade the main transaction lock region to a write lock */
935 if (tdb_allrecord_upgrade(tdb) == -1) {
936 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
937 _tdb_transaction_cancel(tdb);
941 /* get the open lock - this prevents new users attaching to the database
943 if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
944 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
945 _tdb_transaction_cancel(tdb);
949 if (!(tdb->flags & TDB_NOSYNC)) {
950 /* write the recovery data to the end of the file */
951 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
952 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
953 _tdb_transaction_cancel(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_transaction_cancel(tdb);
970 tdb->map_size = tdb->transaction->old_map_size;
971 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
974 /* Keep the open lock until the actual commit */
980 prepare to commit the current transaction
982 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
984 tdb_trace(tdb, "tdb_transaction_prepare_commit");
985 return _tdb_transaction_prepare_commit(tdb);
989 commit the current transaction
991 int tdb_transaction_commit(struct tdb_context *tdb)
993 const struct tdb_methods *methods;
997 if (tdb->transaction == NULL) {
998 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
1002 tdb_trace(tdb, "tdb_transaction_commit");
1004 if (tdb->transaction->transaction_error) {
1005 tdb->ecode = TDB_ERR_IO;
1006 _tdb_transaction_cancel(tdb);
1007 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1012 if (tdb->transaction->nesting != 0) {
1013 tdb->transaction->nesting--;
1017 /* check for a null transaction */
1018 if (tdb->transaction->blocks == NULL) {
1019 _tdb_transaction_cancel(tdb);
1023 if (!tdb->transaction->prepared) {
1024 int ret = _tdb_transaction_prepare_commit(tdb);
1029 methods = tdb->transaction->io_methods;
1031 /* perform all the writes */
1032 for (i=0;i<tdb->transaction->num_blocks;i++) {
1036 if (tdb->transaction->blocks[i] == NULL) {
1040 offset = i * tdb->transaction->block_size;
1041 length = tdb->transaction->block_size;
1042 if (i == tdb->transaction->num_blocks-1) {
1043 length = tdb->transaction->last_block_size;
1046 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1047 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1049 /* we've overwritten part of the data and
1050 possibly expanded the file, so we need to
1051 run the crash recovery code */
1052 tdb->methods = methods;
1053 tdb_transaction_recover(tdb);
1055 _tdb_transaction_cancel(tdb);
1057 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1060 SAFE_FREE(tdb->transaction->blocks[i]);
1063 SAFE_FREE(tdb->transaction->blocks);
1064 tdb->transaction->num_blocks = 0;
1066 /* ensure the new data is on disk */
1067 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1072 TODO: maybe write to some dummy hdr field, or write to magic
1073 offset without mmap, before the last sync, instead of the
1077 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1078 don't change the mtime of the file, this means the file may
1079 not be backed up (as tdb rounding to block sizes means that
1080 file size changes are quite rare too). The following forces
1081 mtime changes when a transaction completes */
1083 utime(tdb->name, NULL);
1086 need_repack = tdb->transaction->need_repack;
1088 /* use a transaction cancel to free memory and remove the
1089 transaction locks */
1090 _tdb_transaction_cancel(tdb);
1093 return tdb_repack(tdb);
1101 recover from an aborted transaction. Must be called with exclusive
1102 database write access already established (including the open
1103 lock to prevent new processes attaching)
1105 int tdb_transaction_recover(struct tdb_context *tdb)
1107 tdb_off_t recovery_head, recovery_eof;
1108 unsigned char *data, *p;
1110 struct tdb_record rec;
1112 /* find the recovery area */
1113 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1114 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1115 tdb->ecode = TDB_ERR_IO;
1119 if (recovery_head == 0) {
1120 /* we have never allocated a recovery record */
1124 /* read the recovery record */
1125 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1126 sizeof(rec), DOCONV()) == -1) {
1127 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1128 tdb->ecode = TDB_ERR_IO;
1132 if (rec.magic != TDB_RECOVERY_MAGIC) {
1133 /* there is no valid recovery data */
1137 if (tdb->read_only) {
1138 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1139 tdb->ecode = TDB_ERR_CORRUPT;
1143 recovery_eof = rec.key_len;
1145 data = (unsigned char *)malloc(rec.data_len);
1147 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1148 tdb->ecode = TDB_ERR_OOM;
1152 /* read the full recovery data */
1153 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1154 rec.data_len, 0) == -1) {
1155 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1156 tdb->ecode = TDB_ERR_IO;
1160 /* recover the file data */
1162 while (p+8 < data + rec.data_len) {
1168 memcpy(&len, p+4, 4);
1170 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1172 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1173 tdb->ecode = TDB_ERR_IO;
1181 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1182 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1183 tdb->ecode = TDB_ERR_IO;
1187 /* if the recovery area is after the recovered eof then remove it */
1188 if (recovery_eof <= recovery_head) {
1189 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1190 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1191 tdb->ecode = TDB_ERR_IO;
1196 /* remove the recovery magic */
1197 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
1199 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1200 tdb->ecode = TDB_ERR_IO;
1204 /* reduce the file size to the old size */
1206 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1207 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1208 tdb->ecode = TDB_ERR_IO;
1211 tdb->map_size = recovery_eof;
1214 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1215 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1216 tdb->ecode = TDB_ERR_IO;
1220 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",