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 /* old file size before transaction */
125 tdb_len_t old_map_size;
130 read while in a transaction. We need to check first if the data is in our list
131 of transaction elements, then if not do a real read
133 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
134 tdb_len_t len, int cv)
138 /* break it down into block sized ops */
139 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
140 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
141 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
146 buf = (void *)(len2 + (char *)buf);
153 blk = off / tdb->transaction->block_size;
155 /* see if we have it in the block list */
156 if (tdb->transaction->num_blocks <= blk ||
157 tdb->transaction->blocks[blk] == NULL) {
158 /* nope, do a real read */
159 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
165 /* it is in the block list. Now check for the last block */
166 if (blk == tdb->transaction->num_blocks-1) {
167 if (len > tdb->transaction->last_block_size) {
172 /* now copy it out of this block */
173 memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
175 tdb_convert(buf, len);
180 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
181 tdb->ecode = TDB_ERR_IO;
182 tdb->transaction->transaction_error = 1;
188 write while in a transaction
190 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
191 const void *buf, tdb_len_t len)
195 /* if the write is to a hash head, then update the transaction
197 if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
198 off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
199 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
200 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
203 /* break it up into block sized chunks */
204 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
205 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
206 if (transaction_write(tdb, off, buf, len2) != 0) {
212 buf = (const void *)(len2 + (const char *)buf);
220 blk = off / tdb->transaction->block_size;
221 off = off % tdb->transaction->block_size;
223 if (tdb->transaction->num_blocks <= blk) {
224 uint8_t **new_blocks;
225 /* expand the blocks array */
226 if (tdb->transaction->blocks == NULL) {
227 new_blocks = (uint8_t **)malloc(
228 (blk+1)*sizeof(uint8_t *));
230 new_blocks = (uint8_t **)realloc(
231 tdb->transaction->blocks,
232 (blk+1)*sizeof(uint8_t *));
234 if (new_blocks == NULL) {
235 tdb->ecode = TDB_ERR_OOM;
238 memset(&new_blocks[tdb->transaction->num_blocks], 0,
239 (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
240 tdb->transaction->blocks = new_blocks;
241 tdb->transaction->num_blocks = blk+1;
242 tdb->transaction->last_block_size = 0;
245 /* allocate and fill a block? */
246 if (tdb->transaction->blocks[blk] == NULL) {
247 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
248 if (tdb->transaction->blocks[blk] == NULL) {
249 tdb->ecode = TDB_ERR_OOM;
250 tdb->transaction->transaction_error = 1;
253 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
254 tdb_len_t len2 = tdb->transaction->block_size;
255 if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
256 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
258 if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
259 tdb->transaction->blocks[blk],
261 SAFE_FREE(tdb->transaction->blocks[blk]);
262 tdb->ecode = TDB_ERR_IO;
265 if (blk == tdb->transaction->num_blocks-1) {
266 tdb->transaction->last_block_size = len2;
271 /* overwrite part of an existing block */
273 memset(tdb->transaction->blocks[blk] + off, 0, len);
275 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
277 if (blk == tdb->transaction->num_blocks-1) {
278 if (len + off > tdb->transaction->last_block_size) {
279 tdb->transaction->last_block_size = len + off;
286 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
287 (blk*tdb->transaction->block_size) + off, len));
288 tdb->transaction->transaction_error = 1;
294 write while in a transaction - this varient never expands the transaction blocks, it only
295 updates existing blocks. This means it cannot change the recovery size
297 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
298 const void *buf, tdb_len_t len)
302 /* break it up into block sized chunks */
303 while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
304 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
305 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
311 buf = (const void *)(len2 + (const char *)buf);
319 blk = off / tdb->transaction->block_size;
320 off = off % tdb->transaction->block_size;
322 if (tdb->transaction->num_blocks <= blk ||
323 tdb->transaction->blocks[blk] == NULL) {
327 if (blk == tdb->transaction->num_blocks-1 &&
328 off + len > tdb->transaction->last_block_size) {
329 if (off >= tdb->transaction->last_block_size) {
332 len = tdb->transaction->last_block_size - off;
335 /* overwrite part of an existing block */
336 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
343 accelerated hash chain head search, using the cached hash heads
345 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
348 for (;h < tdb->header.hash_size;h++) {
349 /* the +1 takes account of the freelist */
350 if (0 != tdb->transaction->hash_heads[h+1]) {
358 out of bounds check during a transaction
360 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
362 if (len <= tdb->map_size) {
365 return TDB_ERRCODE(TDB_ERR_IO, -1);
369 transaction version of tdb_expand().
371 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
374 /* add a write to the transaction elements, so subsequent
375 reads see the zero data */
376 if (transaction_write(tdb, size, NULL, addition) != 0) {
384 brlock during a transaction - ignore them
386 static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset,
387 int rw_type, int lck_type, int probe, size_t len)
392 static const struct tdb_methods transaction_methods = {
395 transaction_next_hash_chain,
397 transaction_expand_file,
401 int tdb_transaction_cancel_internal(struct tdb_context *tdb)
405 if (tdb->transaction == NULL) {
406 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
410 if (tdb->transaction->nesting != 0) {
411 tdb->transaction->transaction_error = 1;
412 tdb->transaction->nesting--;
416 tdb->map_size = tdb->transaction->old_map_size;
418 /* free all the transaction blocks */
419 for (i=0;i<tdb->transaction->num_blocks;i++) {
420 if (tdb->transaction->blocks[i] != NULL) {
421 free(tdb->transaction->blocks[i]);
424 SAFE_FREE(tdb->transaction->blocks);
426 /* remove any global lock created during the transaction */
427 if (tdb->global_lock.count != 0) {
428 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size);
429 tdb->global_lock.count = 0;
432 /* remove any locks created during the transaction */
433 if (tdb->num_locks != 0) {
434 for (i=0;i<tdb->num_lockrecs;i++) {
435 tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
436 F_UNLCK,F_SETLKW, 0, 1);
439 tdb->num_lockrecs = 0;
440 SAFE_FREE(tdb->lockrecs);
443 /* restore the normal io methods */
444 tdb->methods = tdb->transaction->io_methods;
446 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
447 tdb_transaction_unlock(tdb);
448 SAFE_FREE(tdb->transaction->hash_heads);
449 SAFE_FREE(tdb->transaction);
455 start a tdb transaction. No token is returned, as only a single
456 transaction is allowed to be pending per tdb_context
458 int tdb_transaction_start(struct tdb_context *tdb)
460 tdb_trace(tdb, "tdb_transaction_start\n");
462 /* some sanity checks */
463 if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
464 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
465 tdb->ecode = TDB_ERR_EINVAL;
469 /* cope with nested tdb_transaction_start() calls */
470 if (tdb->transaction != NULL) {
471 if (!tdb->flags & TDB_NO_NESTING) {
472 tdb->transaction->nesting++;
473 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
474 tdb->transaction->nesting));
477 tdb_transaction_cancel_internal(tdb);
478 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: cancelling previous transaction\n"));
482 if (tdb->num_locks != 0 || tdb->global_lock.count) {
483 /* the caller must not have any locks when starting a
484 transaction as otherwise we'll be screwed by lack
485 of nested locks in posix */
486 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
487 tdb->ecode = TDB_ERR_LOCK;
491 if (tdb->travlocks.next != NULL) {
492 /* you cannot use transactions inside a traverse (although you can use
493 traverse inside a transaction) as otherwise you can end up with
495 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
496 tdb->ecode = TDB_ERR_LOCK;
500 tdb->transaction = (struct tdb_transaction *)
501 calloc(sizeof(struct tdb_transaction), 1);
502 if (tdb->transaction == NULL) {
503 tdb->ecode = TDB_ERR_OOM;
507 /* a page at a time seems like a reasonable compromise between compactness and efficiency */
508 tdb->transaction->block_size = tdb->page_size;
510 /* get the transaction write lock. This is a blocking lock. As
511 discussed with Volker, there are a number of ways we could
512 make this async, which we will probably do in the future */
513 if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
514 SAFE_FREE(tdb->transaction->blocks);
515 SAFE_FREE(tdb->transaction);
519 /* get a read lock from the freelist to the end of file. This
520 is upgraded to a write lock during the commit */
521 if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) {
522 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
523 tdb->ecode = TDB_ERR_LOCK;
527 /* setup a copy of the hash table heads so the hash scan in
528 traverse can be fast */
529 tdb->transaction->hash_heads = (uint32_t *)
530 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
531 if (tdb->transaction->hash_heads == NULL) {
532 tdb->ecode = TDB_ERR_OOM;
535 if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
536 TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
537 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
538 tdb->ecode = TDB_ERR_IO;
542 /* make sure we know about any file expansions already done by
544 tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
545 tdb->transaction->old_map_size = tdb->map_size;
547 /* finally hook the io methods, replacing them with
548 transaction specific methods */
549 tdb->transaction->io_methods = tdb->methods;
550 tdb->methods = &transaction_methods;
555 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
556 tdb_transaction_unlock(tdb);
557 SAFE_FREE(tdb->transaction->blocks);
558 SAFE_FREE(tdb->transaction->hash_heads);
559 SAFE_FREE(tdb->transaction);
565 cancel the current transaction
567 int tdb_transaction_cancel(struct tdb_context *tdb)
569 tdb_trace(tdb, "tdb_transaction_cancel\n");
570 return tdb_transaction_cancel_internal(tdb);
575 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
577 if (fsync(tdb->fd) != 0) {
578 tdb->ecode = TDB_ERR_IO;
579 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
584 tdb_off_t moffset = offset & ~(tdb->page_size-1);
585 if (msync(moffset + (char *)tdb->map_ptr,
586 length + (offset - moffset), MS_SYNC) != 0) {
587 tdb->ecode = TDB_ERR_IO;
588 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
599 work out how much space the linearised recovery data will consume
601 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
603 tdb_len_t recovery_size = 0;
606 recovery_size = sizeof(uint32_t);
607 for (i=0;i<tdb->transaction->num_blocks;i++) {
608 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
611 if (tdb->transaction->blocks[i] == NULL) {
614 recovery_size += 2*sizeof(tdb_off_t);
615 if (i == tdb->transaction->num_blocks-1) {
616 recovery_size += tdb->transaction->last_block_size;
618 recovery_size += tdb->transaction->block_size;
622 return recovery_size;
626 allocate the recovery area, or use an existing recovery area if it is
629 static int tdb_recovery_allocate(struct tdb_context *tdb,
630 tdb_len_t *recovery_size,
631 tdb_off_t *recovery_offset,
632 tdb_len_t *recovery_max_size)
634 struct list_struct rec;
635 const struct tdb_methods *methods = tdb->transaction->io_methods;
636 tdb_off_t recovery_head;
638 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
639 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
645 if (recovery_head != 0 &&
646 methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
647 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
651 *recovery_size = tdb_recovery_size(tdb);
653 if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
654 /* it fits in the existing area */
655 *recovery_max_size = rec.rec_len;
656 *recovery_offset = recovery_head;
660 /* we need to free up the old recovery area, then allocate a
661 new one at the end of the file. Note that we cannot use
662 tdb_allocate() to allocate the new one as that might return
663 us an area that is being currently used (as of the start of
665 if (recovery_head != 0) {
666 if (tdb_free(tdb, recovery_head, &rec) == -1) {
667 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
672 /* the tdb_free() call might have increased the recovery size */
673 *recovery_size = tdb_recovery_size(tdb);
675 /* round up to a multiple of page size */
676 *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
677 *recovery_offset = tdb->map_size;
678 recovery_head = *recovery_offset;
680 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
681 (tdb->map_size - tdb->transaction->old_map_size) +
682 sizeof(rec) + *recovery_max_size) == -1) {
683 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
687 /* remap the file (if using mmap) */
688 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
690 /* we have to reset the old map size so that we don't try to expand the file
691 again in the transaction commit, which would destroy the recovery area */
692 tdb->transaction->old_map_size = tdb->map_size;
694 /* write the recovery header offset and sync - we can sync without a race here
695 as the magic ptr in the recovery record has not been set */
696 CONVERT(recovery_head);
697 if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
698 &recovery_head, sizeof(tdb_off_t)) == -1) {
699 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
702 if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
703 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
712 setup the recovery data that will be used on a crash during commit
714 static int transaction_setup_recovery(struct tdb_context *tdb,
715 tdb_off_t *magic_offset)
717 tdb_len_t recovery_size;
718 unsigned char *data, *p;
719 const struct tdb_methods *methods = tdb->transaction->io_methods;
720 struct list_struct *rec;
721 tdb_off_t recovery_offset, recovery_max_size;
722 tdb_off_t old_map_size = tdb->transaction->old_map_size;
723 uint32_t magic, tailer;
727 check that the recovery area has enough space
729 if (tdb_recovery_allocate(tdb, &recovery_size,
730 &recovery_offset, &recovery_max_size) == -1) {
734 data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
736 tdb->ecode = TDB_ERR_OOM;
740 rec = (struct list_struct *)data;
741 memset(rec, 0, sizeof(*rec));
744 rec->data_len = recovery_size;
745 rec->rec_len = recovery_max_size;
746 rec->key_len = old_map_size;
749 /* build the recovery data into a single blob to allow us to do a single
750 large write, which should be more efficient */
751 p = data + sizeof(*rec);
752 for (i=0;i<tdb->transaction->num_blocks;i++) {
756 if (tdb->transaction->blocks[i] == NULL) {
760 offset = i * tdb->transaction->block_size;
761 length = tdb->transaction->block_size;
762 if (i == tdb->transaction->num_blocks-1) {
763 length = tdb->transaction->last_block_size;
766 if (offset >= old_map_size) {
769 if (offset + length > tdb->transaction->old_map_size) {
770 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
772 tdb->ecode = TDB_ERR_CORRUPT;
775 memcpy(p, &offset, 4);
776 memcpy(p+4, &length, 4);
780 /* the recovery area contains the old data, not the
781 new data, so we have to call the original tdb_read
783 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
785 tdb->ecode = TDB_ERR_IO;
792 tailer = sizeof(*rec) + recovery_max_size;
793 memcpy(p, &tailer, 4);
796 /* write the recovery data to the recovery area */
797 if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
798 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
800 tdb->ecode = TDB_ERR_IO;
803 if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
804 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
806 tdb->ecode = TDB_ERR_IO;
810 /* as we don't have ordered writes, we have to sync the recovery
811 data before we update the magic to indicate that the recovery
813 if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
820 magic = TDB_RECOVERY_MAGIC;
823 *magic_offset = recovery_offset + offsetof(struct list_struct, magic);
825 if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
826 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
827 tdb->ecode = TDB_ERR_IO;
830 if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
831 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
832 tdb->ecode = TDB_ERR_IO;
836 /* ensure the recovery magic marker is on disk */
837 if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
845 commit the current transaction
847 int tdb_transaction_commit(struct tdb_context *tdb)
849 const struct tdb_methods *methods;
850 tdb_off_t magic_offset = 0;
854 tdb_trace(tdb, "tdb_transaction_commit\n");
855 if (tdb->transaction == NULL) {
856 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
860 if (tdb->transaction->transaction_error) {
861 tdb->ecode = TDB_ERR_IO;
862 tdb_transaction_cancel_internal(tdb);
863 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
868 if (tdb->transaction->nesting != 0) {
869 tdb->transaction->nesting--;
873 /* check for a null transaction */
874 if (tdb->transaction->blocks == NULL) {
875 tdb_transaction_cancel_internal(tdb);
879 methods = tdb->transaction->io_methods;
881 /* if there are any locks pending then the caller has not
882 nested their locks properly, so fail the transaction */
883 if (tdb->num_locks || tdb->global_lock.count) {
884 tdb->ecode = TDB_ERR_LOCK;
885 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: locks pending on commit\n"));
886 tdb_transaction_cancel_internal(tdb);
890 /* upgrade the main transaction lock region to a write lock */
891 if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
892 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to upgrade hash locks\n"));
893 tdb->ecode = TDB_ERR_LOCK;
894 tdb_transaction_cancel_internal(tdb);
898 /* get the global lock - this prevents new users attaching to the database
900 if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
901 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: failed to get global lock\n"));
902 tdb->ecode = TDB_ERR_LOCK;
903 tdb_transaction_cancel_internal(tdb);
907 if (!(tdb->flags & TDB_NOSYNC)) {
908 /* write the recovery data to the end of the file */
909 if (transaction_setup_recovery(tdb, &magic_offset) == -1) {
910 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to setup recovery data\n"));
911 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
912 tdb_transaction_cancel_internal(tdb);
917 /* expand the file to the new size if needed */
918 if (tdb->map_size != tdb->transaction->old_map_size) {
919 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
921 tdb->transaction->old_map_size) == -1) {
922 tdb->ecode = TDB_ERR_IO;
923 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: expansion failed\n"));
924 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
925 tdb_transaction_cancel_internal(tdb);
928 tdb->map_size = tdb->transaction->old_map_size;
929 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
932 /* perform all the writes */
933 for (i=0;i<tdb->transaction->num_blocks;i++) {
937 if (tdb->transaction->blocks[i] == NULL) {
941 offset = i * tdb->transaction->block_size;
942 length = tdb->transaction->block_size;
943 if (i == tdb->transaction->num_blocks-1) {
944 length = tdb->transaction->last_block_size;
947 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
948 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
950 /* we've overwritten part of the data and
951 possibly expanded the file, so we need to
952 run the crash recovery code */
953 tdb->methods = methods;
954 tdb_transaction_recover(tdb);
956 tdb_transaction_cancel_internal(tdb);
957 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
959 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
962 SAFE_FREE(tdb->transaction->blocks[i]);
965 SAFE_FREE(tdb->transaction->blocks);
966 tdb->transaction->num_blocks = 0;
968 if (!(tdb->flags & TDB_NOSYNC)) {
969 /* ensure the new data is on disk */
970 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
974 /* remove the recovery marker */
975 if (methods->tdb_write(tdb, magic_offset, &zero, 4) == -1) {
976 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to remove recovery magic\n"));
980 /* ensure the recovery marker has been removed on disk */
981 if (transaction_sync(tdb, magic_offset, 4) == -1) {
986 tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
989 TODO: maybe write to some dummy hdr field, or write to magic
990 offset without mmap, before the last sync, instead of the
994 /* on some systems (like Linux 2.6.x) changes via mmap/msync
995 don't change the mtime of the file, this means the file may
996 not be backed up (as tdb rounding to block sizes means that
997 file size changes are quite rare too). The following forces
998 mtime changes when a transaction completes */
1000 utime(tdb->name, NULL);
1003 /* use a transaction cancel to free memory and remove the
1004 transaction locks */
1005 tdb_transaction_cancel_internal(tdb);
1012 recover from an aborted transaction. Must be called with exclusive
1013 database write access already established (including the global
1014 lock to prevent new processes attaching)
1016 int tdb_transaction_recover(struct tdb_context *tdb)
1018 tdb_off_t recovery_head, recovery_eof;
1019 unsigned char *data, *p;
1021 struct list_struct rec;
1023 /* find the recovery area */
1024 if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1025 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1026 tdb->ecode = TDB_ERR_IO;
1030 if (recovery_head == 0) {
1031 /* we have never allocated a recovery record */
1035 /* read the recovery record */
1036 if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1037 sizeof(rec), DOCONV()) == -1) {
1038 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1039 tdb->ecode = TDB_ERR_IO;
1043 if (rec.magic != TDB_RECOVERY_MAGIC) {
1044 /* there is no valid recovery data */
1048 if (tdb->read_only) {
1049 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1050 tdb->ecode = TDB_ERR_CORRUPT;
1054 recovery_eof = rec.key_len;
1056 data = (unsigned char *)malloc(rec.data_len);
1058 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1059 tdb->ecode = TDB_ERR_OOM;
1063 /* read the full recovery data */
1064 if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1065 rec.data_len, 0) == -1) {
1066 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1067 tdb->ecode = TDB_ERR_IO;
1071 /* recover the file data */
1073 while (p+8 < data + rec.data_len) {
1079 memcpy(&len, p+4, 4);
1081 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1083 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1084 tdb->ecode = TDB_ERR_IO;
1092 if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1093 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1094 tdb->ecode = TDB_ERR_IO;
1098 /* if the recovery area is after the recovered eof then remove it */
1099 if (recovery_eof <= recovery_head) {
1100 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1101 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1102 tdb->ecode = TDB_ERR_IO;
1107 /* remove the recovery magic */
1108 if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic),
1110 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1111 tdb->ecode = TDB_ERR_IO;
1115 /* reduce the file size to the old size */
1117 if (ftruncate(tdb->fd, recovery_eof) != 0) {
1118 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1119 tdb->ecode = TDB_ERR_IO;
1122 tdb->map_size = recovery_eof;
1125 if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1126 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1127 tdb->ecode = TDB_ERR_IO;
1131 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",