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->stats.transaction_nest++;
436 tdb->tdb1.transaction->nesting++;
440 if (tdb1_have_extra_locks(tdb)) {
441 /* the caller must not have any locks when starting a
442 transaction as otherwise we'll be screwed by lack
443 of nested locks in posix */
444 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
445 "tdb1_transaction_start: cannot start a"
446 " transaction with locks held");
450 if (tdb->tdb1.travlocks.next != NULL) {
451 /* you cannot use transactions inside a traverse (although you can use
452 traverse inside a transaction) as otherwise you can end up with
454 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
455 "tdb1_transaction_start: cannot start a"
456 " transaction within a traverse");
460 tdb->tdb1.transaction = (struct tdb1_transaction *)
461 calloc(sizeof(struct tdb1_transaction), 1);
462 if (tdb->tdb1.transaction == NULL) {
463 tdb->last_error = TDB_ERR_OOM;
467 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
468 tdb->tdb1.transaction->block_size = tdb->tdb1.page_size;
470 /* get the transaction write lock. This is a blocking lock. As
471 discussed with Volker, there are a number of ways we could
472 make this async, which we will probably do in the future */
473 if (tdb1_transaction_lock(tdb, F_WRLCK, TDB_LOCK_WAIT) == -1) {
474 SAFE_FREE(tdb->tdb1.transaction->blocks);
475 SAFE_FREE(tdb->tdb1.transaction);
479 /* get a read lock from the freelist to the end of file. This
480 is upgraded to a write lock during the commit */
481 if (tdb1_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
482 if (errno != EAGAIN && errno != EINTR) {
483 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
484 "tdb1_transaction_start:"
485 " failed to get hash locks");
487 goto fail_allrecord_lock;
490 /* setup a copy of the hash table heads so the hash scan in
491 traverse can be fast */
492 tdb->tdb1.transaction->hash_heads = (uint32_t *)
493 calloc(tdb->tdb1.header.hash_size+1, sizeof(uint32_t));
494 if (tdb->tdb1.transaction->hash_heads == NULL) {
495 tdb->last_error = TDB_ERR_OOM;
498 if (tdb->tdb1.io->tdb1_read(tdb, TDB1_FREELIST_TOP, tdb->tdb1.transaction->hash_heads,
499 TDB1_HASHTABLE_SIZE(tdb), 0) != 0) {
500 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
501 "tdb1_transaction_start: failed to read hash heads");
505 /* make sure we know about any file expansions already done by
507 tdb->tdb1.io->tdb1_oob(tdb, tdb->file->map_size + 1, 1);
508 tdb->tdb1.transaction->old_map_size = tdb->file->map_size;
510 /* finally hook the io methods, replacing them with
511 transaction specific methods */
512 tdb->tdb1.transaction->io_methods = tdb->tdb1.io;
513 tdb->tdb1.io = &transaction1_methods;
515 tdb->stats.transactions++;
519 tdb1_allrecord_unlock(tdb, F_RDLCK);
521 tdb1_transaction_unlock(tdb, F_WRLCK);
522 SAFE_FREE(tdb->tdb1.transaction->blocks);
523 SAFE_FREE(tdb->tdb1.transaction->hash_heads);
524 SAFE_FREE(tdb->tdb1.transaction);
528 int tdb1_transaction_start(struct tdb_context *tdb)
530 return _tdb1_transaction_start(tdb);
536 static int transaction1_sync(struct tdb_context *tdb, tdb1_off_t offset, tdb1_len_t length)
538 if (tdb->flags & TDB_NOSYNC) {
543 if (fdatasync(tdb->file->fd) != 0) {
545 if (fsync(tdb->file->fd) != 0) {
547 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
548 "tdb1_transaction: fsync failed");
552 if (tdb->file->map_ptr) {
553 tdb1_off_t moffset = offset & ~(tdb->tdb1.page_size-1);
554 if (msync(moffset + (char *)tdb->file->map_ptr,
555 length + (offset - moffset), MS_SYNC) != 0) {
556 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
558 " msync failed - %s",
568 static int _tdb1_transaction_cancel(struct tdb_context *tdb)
572 if (tdb->tdb1.transaction == NULL) {
573 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
574 "tdb1_transaction_cancel:"
579 if (tdb->tdb1.transaction->nesting != 0) {
580 tdb->tdb1.transaction->transaction_error = 1;
581 tdb->tdb1.transaction->nesting--;
585 tdb->file->map_size = tdb->tdb1.transaction->old_map_size;
587 /* free all the transaction blocks */
588 for (i=0;i<tdb->tdb1.transaction->num_blocks;i++) {
589 if (tdb->tdb1.transaction->blocks[i] != NULL) {
590 free(tdb->tdb1.transaction->blocks[i]);
593 SAFE_FREE(tdb->tdb1.transaction->blocks);
595 if (tdb->tdb1.transaction->magic_offset) {
596 const struct tdb1_methods *methods = tdb->tdb1.transaction->io_methods;
597 const uint32_t invalid = TDB1_RECOVERY_INVALID_MAGIC;
599 /* remove the recovery marker */
600 if (methods->tdb1_write(tdb, tdb->tdb1.transaction->magic_offset, &invalid, 4) == -1 ||
601 transaction1_sync(tdb, tdb->tdb1.transaction->magic_offset, 4) == -1) {
602 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
603 "tdb1_transaction_cancel: failed to"
604 " remove recovery magic");
609 /* This also removes the OPEN_LOCK, if we have it. */
610 tdb1_release_transaction_locks(tdb);
612 /* restore the normal io methods */
613 tdb->tdb1.io = tdb->tdb1.transaction->io_methods;
615 SAFE_FREE(tdb->tdb1.transaction->hash_heads);
616 SAFE_FREE(tdb->tdb1.transaction);
622 cancel the current transaction
624 int tdb1_transaction_cancel(struct tdb_context *tdb)
626 tdb->stats.transaction_cancel++;
627 return _tdb1_transaction_cancel(tdb);
631 work out how much space the linearised recovery data will consume
633 static tdb1_len_t tdb1_recovery_size(struct tdb_context *tdb)
635 tdb1_len_t recovery_size = 0;
638 recovery_size = sizeof(uint32_t);
639 for (i=0;i<tdb->tdb1.transaction->num_blocks;i++) {
640 if (i * tdb->tdb1.transaction->block_size >= tdb->tdb1.transaction->old_map_size) {
643 if (tdb->tdb1.transaction->blocks[i] == NULL) {
646 recovery_size += 2*sizeof(tdb1_off_t);
647 if (i == tdb->tdb1.transaction->num_blocks-1) {
648 recovery_size += tdb->tdb1.transaction->last_block_size;
650 recovery_size += tdb->tdb1.transaction->block_size;
654 return recovery_size;
657 int tdb1_recovery_area(struct tdb_context *tdb,
658 const struct tdb1_methods *methods,
659 tdb1_off_t *recovery_offset,
660 struct tdb1_record *rec)
662 if (tdb1_ofs_read(tdb, TDB1_RECOVERY_HEAD, recovery_offset) == -1) {
666 if (*recovery_offset == 0) {
671 if (methods->tdb1_read(tdb, *recovery_offset, rec, sizeof(*rec),
672 TDB1_DOCONV()) == -1) {
676 /* ignore invalid recovery regions: can happen in crash */
677 if (rec->magic != TDB1_RECOVERY_MAGIC &&
678 rec->magic != TDB1_RECOVERY_INVALID_MAGIC) {
679 *recovery_offset = 0;
686 allocate the recovery area, or use an existing recovery area if it is
689 static int tdb1_recovery_allocate(struct tdb_context *tdb,
690 tdb1_len_t *recovery_size,
691 tdb1_off_t *recovery_offset,
692 tdb1_len_t *recovery_max_size)
694 struct tdb1_record rec;
695 const struct tdb1_methods *methods = tdb->tdb1.transaction->io_methods;
696 tdb1_off_t recovery_head;
698 if (tdb1_recovery_area(tdb, methods, &recovery_head, &rec) == -1) {
699 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
700 "tdb1_recovery_allocate:"
701 " failed to read recovery head");
705 *recovery_size = tdb1_recovery_size(tdb);
707 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
708 /* it fits in the existing area */
709 *recovery_max_size = rec.rec_len;
710 *recovery_offset = recovery_head;
714 /* we need to free up the old recovery area, then allocate a
715 new one at the end of the file. Note that we cannot use
716 tdb1_allocate() to allocate the new one as that might return
717 us an area that is being currently used (as of the start of
719 if (recovery_head != 0) {
720 if (tdb1_free(tdb, recovery_head, &rec) == -1) {
721 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
722 "tdb1_recovery_allocate: failed to free"
723 " previous recovery area");
728 /* the tdb1_free() call might have increased the recovery size */
729 *recovery_size = tdb1_recovery_size(tdb);
731 /* round up to a multiple of page size */
732 *recovery_max_size = TDB1_ALIGN(sizeof(rec) + *recovery_size,
733 tdb->tdb1.page_size) - sizeof(rec);
734 *recovery_offset = tdb->file->map_size;
735 recovery_head = *recovery_offset;
737 if (methods->tdb1_expand_file(tdb, tdb->tdb1.transaction->old_map_size,
738 (tdb->file->map_size - tdb->tdb1.transaction->old_map_size) +
739 sizeof(rec) + *recovery_max_size) == -1) {
740 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
741 "tdb1_recovery_allocate:"
742 " failed to create recovery area");
745 tdb->stats.transaction_expand_file++;
747 /* remap the file (if using mmap) */
748 methods->tdb1_oob(tdb, tdb->file->map_size + 1, 1);
750 /* we have to reset the old map size so that we don't try to expand the file
751 again in the transaction commit, which would destroy the recovery area */
752 tdb->tdb1.transaction->old_map_size = tdb->file->map_size;
754 /* write the recovery header offset and sync - we can sync without a race here
755 as the magic ptr in the recovery record has not been set */
756 TDB1_CONV(recovery_head);
757 if (methods->tdb1_write(tdb, TDB1_RECOVERY_HEAD,
758 &recovery_head, sizeof(tdb1_off_t)) == -1) {
759 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
760 "tdb1_recovery_allocate:"
761 " failed to write recovery head");
764 if (transaction1_write_existing(tdb, TDB1_RECOVERY_HEAD, &recovery_head, sizeof(tdb1_off_t)) == -1) {
765 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
766 "tdb1_recovery_allocate:"
767 " failed to write recovery head");
776 setup the recovery data that will be used on a crash during commit
778 static int transaction1_setup_recovery(struct tdb_context *tdb,
779 tdb1_off_t *magic_offset)
781 tdb1_len_t recovery_size;
782 unsigned char *data, *p;
783 const struct tdb1_methods *methods = tdb->tdb1.transaction->io_methods;
784 struct tdb1_record *rec;
785 tdb1_off_t recovery_offset, recovery_max_size;
786 tdb1_off_t old_map_size = tdb->tdb1.transaction->old_map_size;
787 uint32_t magic, tailer;
791 check that the recovery area has enough space
793 if (tdb1_recovery_allocate(tdb, &recovery_size,
794 &recovery_offset, &recovery_max_size) == -1) {
798 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
800 tdb->last_error = TDB_ERR_OOM;
804 rec = (struct tdb1_record *)data;
805 memset(rec, 0, sizeof(*rec));
807 rec->magic = TDB1_RECOVERY_INVALID_MAGIC;
808 rec->data_len = recovery_size;
809 rec->rec_len = recovery_max_size;
810 rec->key_len = old_map_size;
813 /* build the recovery data into a single blob to allow us to do a single
814 large write, which should be more efficient */
815 p = data + sizeof(*rec);
816 for (i=0;i<tdb->tdb1.transaction->num_blocks;i++) {
820 if (tdb->tdb1.transaction->blocks[i] == NULL) {
824 offset = i * tdb->tdb1.transaction->block_size;
825 length = tdb->tdb1.transaction->block_size;
826 if (i == tdb->tdb1.transaction->num_blocks-1) {
827 length = tdb->tdb1.transaction->last_block_size;
830 if (offset >= old_map_size) {
833 if (offset + length > tdb->tdb1.transaction->old_map_size) {
834 tdb->last_error = tdb_logerr(tdb, TDB_ERR_CORRUPT,
836 "tdb1_transaction_setup_recovery: transaction data over new region boundary");
840 memcpy(p, &offset, 4);
841 memcpy(p+4, &length, 4);
845 /* the recovery area contains the old data, not the
846 new data, so we have to call the original tdb1_read
848 if (methods->tdb1_read(tdb, offset, p + 8, length, 0) != 0) {
850 tdb->last_error = TDB_ERR_IO;
857 tailer = sizeof(*rec) + recovery_max_size;
858 memcpy(p, &tailer, 4);
863 /* write the recovery data to the recovery area */
864 if (methods->tdb1_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
865 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
866 "tdb1_transaction_setup_recovery:"
867 " failed to write recovery data");
871 if (transaction1_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
872 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
873 "tdb1_transaction_setup_recovery: failed to write"
874 " secondary recovery data");
879 /* as we don't have ordered writes, we have to sync the recovery
880 data before we update the magic to indicate that the recovery
882 if (transaction1_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
889 magic = TDB1_RECOVERY_MAGIC;
892 *magic_offset = recovery_offset + offsetof(struct tdb1_record, magic);
894 if (methods->tdb1_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
895 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
896 "tdb1_transaction_setup_recovery:"
897 " failed to write recovery magic");
900 if (transaction1_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
901 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
902 "tdb1_transaction_setup_recovery:"
903 " failed to write secondary recovery magic");
907 /* ensure the recovery magic marker is on disk */
908 if (transaction1_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
915 static int _tdb1_transaction_prepare_commit(struct tdb_context *tdb)
917 const struct tdb1_methods *methods;
919 if (tdb->tdb1.transaction == NULL) {
920 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
921 "tdb1_transaction_prepare_commit:"
926 if (tdb->tdb1.transaction->prepared) {
927 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
928 "tdb1_transaction_prepare_commit:"
929 " transaction already prepared");
930 _tdb1_transaction_cancel(tdb);
934 if (tdb->tdb1.transaction->transaction_error) {
935 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
936 "tdb1_transaction_prepare_commit:"
937 " transaction error pending");
938 _tdb1_transaction_cancel(tdb);
943 if (tdb->tdb1.transaction->nesting != 0) {
947 /* check for a null transaction */
948 if (tdb->tdb1.transaction->blocks == NULL) {
952 methods = tdb->tdb1.transaction->io_methods;
954 /* if there are any locks pending then the caller has not
955 nested their locks properly, so fail the transaction */
956 if (tdb1_have_extra_locks(tdb)) {
957 tdb->last_error = tdb_logerr(tdb, TDB_ERR_LOCK, TDB_LOG_USE_ERROR,
958 "tdb1_transaction_prepare_commit:"
959 " locks pending on commit");
960 _tdb1_transaction_cancel(tdb);
964 /* upgrade the main transaction lock region to a write lock */
965 if (tdb1_allrecord_upgrade(tdb) == -1) {
966 if (errno != EAGAIN && errno != EINTR) {
967 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
968 "tdb1_transaction_prepare_commit:"
969 " failed to upgrade hash locks");
974 /* get the open lock - this prevents new users attaching to the database
976 if (tdb1_nest_lock(tdb, TDB1_OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
977 if (errno != EAGAIN && errno != EINTR) {
978 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
979 "tdb1_transaction_prepare_commit:"
980 " failed to get open lock");
985 if (!(tdb->flags & TDB_NOSYNC)) {
986 /* write the recovery data to the end of the file */
987 if (transaction1_setup_recovery(tdb, &tdb->tdb1.transaction->magic_offset) == -1) {
988 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
989 "tdb1_transaction_prepare_commit:"
990 " failed to setup recovery data");
995 tdb->tdb1.transaction->prepared = true;
997 /* expand the file to the new size if needed */
998 if (tdb->file->map_size != tdb->tdb1.transaction->old_map_size) {
999 if (methods->tdb1_expand_file(tdb, tdb->tdb1.transaction->old_map_size,
1000 tdb->file->map_size -
1001 tdb->tdb1.transaction->old_map_size) == -1) {
1002 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1003 "tdb1_transaction_prepare_commit:"
1004 " expansion failed");
1007 tdb->stats.transaction_expand_file++;
1008 tdb->file->map_size = tdb->tdb1.transaction->old_map_size;
1009 methods->tdb1_oob(tdb, tdb->file->map_size + 1, 1);
1012 /* Keep the open lock until the actual commit */
1018 prepare to commit the current transaction
1020 int tdb1_transaction_prepare_commit(struct tdb_context *tdb)
1022 return _tdb1_transaction_prepare_commit(tdb);
1025 /* A repack is worthwhile if the largest is less than half total free. */
1026 static bool repack_worthwhile(struct tdb_context *tdb)
1029 struct tdb1_record rec;
1030 tdb1_len_t total = 0, largest = 0;
1032 if (tdb1_ofs_read(tdb, TDB1_FREELIST_TOP, &ptr) == -1) {
1036 while (ptr != 0 && tdb1_rec_free_read(tdb, ptr, &rec) == 0) {
1037 total += rec.rec_len;
1038 if (rec.rec_len > largest) {
1039 largest = rec.rec_len;
1044 return total > largest * 2;
1048 commit the current transaction
1050 int tdb1_transaction_commit(struct tdb_context *tdb)
1052 const struct tdb1_methods *methods;
1054 bool need_repack = false;
1056 if (tdb->tdb1.transaction == NULL) {
1057 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
1058 "tdb1_transaction_commit:"
1063 if (tdb->tdb1.transaction->transaction_error) {
1064 tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
1065 "tdb1_transaction_commit:"
1066 " transaction error pending");
1067 _tdb1_transaction_cancel(tdb);
1072 if (tdb->tdb1.transaction->nesting != 0) {
1073 tdb->tdb1.transaction->nesting--;
1077 /* check for a null transaction */
1078 if (tdb->tdb1.transaction->blocks == NULL) {
1079 _tdb1_transaction_cancel(tdb);
1083 if (!tdb->tdb1.transaction->prepared) {
1084 int ret = _tdb1_transaction_prepare_commit(tdb);
1086 _tdb1_transaction_cancel(tdb);
1091 methods = tdb->tdb1.transaction->io_methods;
1093 /* perform all the writes */
1094 for (i=0;i<tdb->tdb1.transaction->num_blocks;i++) {
1098 if (tdb->tdb1.transaction->blocks[i] == NULL) {
1102 offset = i * tdb->tdb1.transaction->block_size;
1103 length = tdb->tdb1.transaction->block_size;
1104 if (i == tdb->tdb1.transaction->num_blocks-1) {
1105 length = tdb->tdb1.transaction->last_block_size;
1108 if (methods->tdb1_write(tdb, offset, tdb->tdb1.transaction->blocks[i], length) == -1) {
1109 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1110 "tdb1_transaction_commit:"
1111 " write failed during commit");
1113 /* we've overwritten part of the data and
1114 possibly expanded the file, so we need to
1115 run the crash recovery code */
1116 tdb->tdb1.io = methods;
1117 tdb1_transaction_recover(tdb);
1119 _tdb1_transaction_cancel(tdb);
1121 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1122 "tdb1_transaction_commit: write failed");
1125 SAFE_FREE(tdb->tdb1.transaction->blocks[i]);
1128 /* Do this before we drop lock or blocks. */
1129 if (tdb->tdb1.transaction->expanded) {
1130 need_repack = repack_worthwhile(tdb);
1133 SAFE_FREE(tdb->tdb1.transaction->blocks);
1134 tdb->tdb1.transaction->num_blocks = 0;
1136 /* ensure the new data is on disk */
1137 if (transaction1_sync(tdb, 0, tdb->file->map_size) == -1) {
1142 TODO: maybe write to some dummy hdr field, or write to magic
1143 offset without mmap, before the last sync, instead of the
1147 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1148 don't change the mtime of the file, this means the file may
1149 not be backed up (as tdb rounding to block sizes means that
1150 file size changes are quite rare too). The following forces
1151 mtime changes when a transaction completes */
1153 utime(tdb->name, NULL);
1156 /* use a transaction cancel to free memory and remove the
1157 transaction locks */
1158 _tdb1_transaction_cancel(tdb);
1161 return tdb_repack(tdb);
1169 recover from an aborted transaction. Must be called with exclusive
1170 database write access already established (including the open
1171 lock to prevent new processes attaching)
1173 int tdb1_transaction_recover(struct tdb_context *tdb)
1175 tdb1_off_t recovery_head, recovery_eof;
1176 unsigned char *data, *p;
1178 struct tdb1_record rec;
1180 /* find the recovery area */
1181 if (tdb1_ofs_read(tdb, TDB1_RECOVERY_HEAD, &recovery_head) == -1) {
1182 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1183 "tdb1_transaction_recover:"
1184 " failed to read recovery head");
1188 if (recovery_head == 0) {
1189 /* we have never allocated a recovery record */
1193 /* read the recovery record */
1194 if (tdb->tdb1.io->tdb1_read(tdb, recovery_head, &rec,
1195 sizeof(rec), TDB1_DOCONV()) == -1) {
1196 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1197 "tdb1_transaction_recover:"
1198 " failed to read recovery record");
1202 if (rec.magic != TDB1_RECOVERY_MAGIC) {
1203 /* there is no valid recovery data */
1207 if (tdb->flags & TDB_RDONLY) {
1208 tdb->last_error = tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
1209 "tdb1_transaction_recover:"
1210 " attempt to recover read only"
1215 recovery_eof = rec.key_len;
1217 data = (unsigned char *)malloc(rec.data_len);
1219 tdb->last_error = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
1220 "tdb1_transaction_recover:"
1221 " failed to allocate recovery data");
1225 /* read the full recovery data */
1226 if (tdb->tdb1.io->tdb1_read(tdb, recovery_head + sizeof(rec), data,
1227 rec.data_len, 0) == -1) {
1228 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1229 "tdb1_transaction_recover:"
1230 " failed to read recovery data");
1234 /* recover the file data */
1236 while (p+8 < data + rec.data_len) {
1238 if (TDB1_DOCONV()) {
1242 memcpy(&len, p+4, 4);
1244 if (tdb->tdb1.io->tdb1_write(tdb, ofs, p+8, len) == -1) {
1246 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1247 "tdb1_transaction_recover: failed to recover"
1248 " %d bytes at offset %d", len, ofs);
1256 if (transaction1_sync(tdb, 0, tdb->file->map_size) == -1) {
1257 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1258 "tdb1_transaction_recover: failed to sync recovery");
1262 /* if the recovery area is after the recovered eof then remove it */
1263 if (recovery_eof <= recovery_head) {
1264 if (tdb1_ofs_write(tdb, TDB1_RECOVERY_HEAD, &zero) == -1) {
1265 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1266 "tdb1_transaction_recover: failed to remove"
1272 /* remove the recovery magic */
1273 if (tdb1_ofs_write(tdb, recovery_head + offsetof(struct tdb1_record, magic),
1275 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1276 "tdb1_transaction_recover: failed to remove"
1281 if (transaction1_sync(tdb, 0, recovery_eof) == -1) {
1282 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
1283 "tdb1_transaction_recover:"
1284 " failed to sync2 recovery");
1288 tdb_logerr(tdb, TDB_SUCCESS, TDB_LOG_WARNING,
1289 "tdb1_transaction_recover: recovered %d byte database",
1296 /* Any I/O failures we say "needs recovery". */
1297 tdb_bool_err tdb1_needs_recovery(struct tdb_context *tdb)
1299 tdb1_off_t recovery_head;
1300 struct tdb1_record rec;
1302 /* find the recovery area */
1303 if (tdb1_ofs_read(tdb, TDB1_RECOVERY_HEAD, &recovery_head) == -1) {
1304 return tdb->last_error;
1307 if (recovery_head == 0) {
1308 /* we have never allocated a recovery record */
1312 /* read the recovery record */
1313 if (tdb->tdb1.io->tdb1_read(tdb, recovery_head, &rec,
1314 sizeof(rec), TDB1_DOCONV()) == -1) {
1315 return tdb->last_error;
1318 return (rec.magic == TDB1_RECOVERY_MAGIC);