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 /* set when the OPEN_LOCK has been taken */
139 bool open_lock_taken
;
141 /* old file size before transaction */
142 tdb_len_t old_map_size
;
144 /* we should re-pack on commit */
150 read while in a transaction. We need to check first if the data is in our list
151 of transaction elements, then if not do a real read
153 static int transaction_read(struct tdb_context
*tdb
, tdb_off_t off
, void *buf
,
154 tdb_len_t len
, int cv
)
158 /* break it down into block sized ops */
159 while (len
+ (off
% tdb
->transaction
->block_size
) > tdb
->transaction
->block_size
) {
160 tdb_len_t len2
= tdb
->transaction
->block_size
- (off
% tdb
->transaction
->block_size
);
161 if (transaction_read(tdb
, off
, buf
, len2
, cv
) != 0) {
166 buf
= (void *)(len2
+ (char *)buf
);
173 blk
= off
/ tdb
->transaction
->block_size
;
175 /* see if we have it in the block list */
176 if (tdb
->transaction
->num_blocks
<= blk
||
177 tdb
->transaction
->blocks
[blk
] == NULL
) {
178 /* nope, do a real read */
179 if (tdb
->transaction
->io_methods
->tdb_read(tdb
, off
, buf
, len
, cv
) != 0) {
185 /* it is in the block list. Now check for the last block */
186 if (blk
== tdb
->transaction
->num_blocks
-1) {
187 if (len
> tdb
->transaction
->last_block_size
) {
192 /* now copy it out of this block */
193 memcpy(buf
, tdb
->transaction
->blocks
[blk
] + (off
% tdb
->transaction
->block_size
), len
);
195 tdb_convert(buf
, len
);
200 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "transaction_read: failed at off=%d len=%d\n", off
, len
));
201 tdb
->ecode
= TDB_ERR_IO
;
202 tdb
->transaction
->transaction_error
= 1;
208 write while in a transaction
210 static int transaction_write(struct tdb_context
*tdb
, tdb_off_t off
,
211 const void *buf
, tdb_len_t len
)
215 /* Only a commit is allowed on a prepared transaction */
216 if (tdb
->transaction
->prepared
) {
217 tdb
->ecode
= TDB_ERR_EINVAL
;
218 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "transaction_write: transaction already prepared, write not allowed\n"));
219 tdb
->transaction
->transaction_error
= 1;
223 /* if the write is to a hash head, then update the transaction
225 if (len
== sizeof(tdb_off_t
) && off
>= FREELIST_TOP
&&
226 off
< FREELIST_TOP
+TDB_HASHTABLE_SIZE(tdb
)) {
227 uint32_t chain
= (off
-FREELIST_TOP
) / sizeof(tdb_off_t
);
228 memcpy(&tdb
->transaction
->hash_heads
[chain
], buf
, len
);
231 /* break it up into block sized chunks */
232 while (len
+ (off
% tdb
->transaction
->block_size
) > tdb
->transaction
->block_size
) {
233 tdb_len_t len2
= tdb
->transaction
->block_size
- (off
% tdb
->transaction
->block_size
);
234 if (transaction_write(tdb
, off
, buf
, len2
) != 0) {
240 buf
= (const void *)(len2
+ (const char *)buf
);
248 blk
= off
/ tdb
->transaction
->block_size
;
249 off
= off
% tdb
->transaction
->block_size
;
251 if (tdb
->transaction
->num_blocks
<= blk
) {
252 uint8_t **new_blocks
;
253 /* expand the blocks array */
254 if (tdb
->transaction
->blocks
== NULL
) {
255 new_blocks
= (uint8_t **)malloc(
256 (blk
+1)*sizeof(uint8_t *));
258 new_blocks
= (uint8_t **)realloc(
259 tdb
->transaction
->blocks
,
260 (blk
+1)*sizeof(uint8_t *));
262 if (new_blocks
== NULL
) {
263 tdb
->ecode
= TDB_ERR_OOM
;
266 memset(&new_blocks
[tdb
->transaction
->num_blocks
], 0,
267 (1+(blk
- tdb
->transaction
->num_blocks
))*sizeof(uint8_t *));
268 tdb
->transaction
->blocks
= new_blocks
;
269 tdb
->transaction
->num_blocks
= blk
+1;
270 tdb
->transaction
->last_block_size
= 0;
273 /* allocate and fill a block? */
274 if (tdb
->transaction
->blocks
[blk
] == NULL
) {
275 tdb
->transaction
->blocks
[blk
] = (uint8_t *)calloc(tdb
->transaction
->block_size
, 1);
276 if (tdb
->transaction
->blocks
[blk
] == NULL
) {
277 tdb
->ecode
= TDB_ERR_OOM
;
278 tdb
->transaction
->transaction_error
= 1;
281 if (tdb
->transaction
->old_map_size
> blk
* tdb
->transaction
->block_size
) {
282 tdb_len_t len2
= tdb
->transaction
->block_size
;
283 if (len2
+ (blk
* tdb
->transaction
->block_size
) > tdb
->transaction
->old_map_size
) {
284 len2
= tdb
->transaction
->old_map_size
- (blk
* tdb
->transaction
->block_size
);
286 if (tdb
->transaction
->io_methods
->tdb_read(tdb
, blk
* tdb
->transaction
->block_size
,
287 tdb
->transaction
->blocks
[blk
],
289 SAFE_FREE(tdb
->transaction
->blocks
[blk
]);
290 tdb
->ecode
= TDB_ERR_IO
;
293 if (blk
== tdb
->transaction
->num_blocks
-1) {
294 tdb
->transaction
->last_block_size
= len2
;
299 /* overwrite part of an existing block */
301 memset(tdb
->transaction
->blocks
[blk
] + off
, 0, len
);
303 memcpy(tdb
->transaction
->blocks
[blk
] + off
, buf
, len
);
305 if (blk
== tdb
->transaction
->num_blocks
-1) {
306 if (len
+ off
> tdb
->transaction
->last_block_size
) {
307 tdb
->transaction
->last_block_size
= len
+ off
;
314 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "transaction_write: failed at off=%d len=%d\n",
315 (blk
*tdb
->transaction
->block_size
) + off
, len
));
316 tdb
->transaction
->transaction_error
= 1;
322 write while in a transaction - this varient never expands the transaction blocks, it only
323 updates existing blocks. This means it cannot change the recovery size
325 static int transaction_write_existing(struct tdb_context
*tdb
, tdb_off_t off
,
326 const void *buf
, tdb_len_t len
)
330 /* break it up into block sized chunks */
331 while (len
+ (off
% tdb
->transaction
->block_size
) > tdb
->transaction
->block_size
) {
332 tdb_len_t len2
= tdb
->transaction
->block_size
- (off
% tdb
->transaction
->block_size
);
333 if (transaction_write_existing(tdb
, off
, buf
, len2
) != 0) {
339 buf
= (const void *)(len2
+ (const char *)buf
);
347 blk
= off
/ tdb
->transaction
->block_size
;
348 off
= off
% tdb
->transaction
->block_size
;
350 if (tdb
->transaction
->num_blocks
<= blk
||
351 tdb
->transaction
->blocks
[blk
] == NULL
) {
355 if (blk
== tdb
->transaction
->num_blocks
-1 &&
356 off
+ len
> tdb
->transaction
->last_block_size
) {
357 if (off
>= tdb
->transaction
->last_block_size
) {
360 len
= tdb
->transaction
->last_block_size
- off
;
363 /* overwrite part of an existing block */
364 memcpy(tdb
->transaction
->blocks
[blk
] + off
, buf
, len
);
371 accelerated hash chain head search, using the cached hash heads
373 static void transaction_next_hash_chain(struct tdb_context
*tdb
, uint32_t *chain
)
376 for (;h
< tdb
->header
.hash_size
;h
++) {
377 /* the +1 takes account of the freelist */
378 if (0 != tdb
->transaction
->hash_heads
[h
+1]) {
386 out of bounds check during a transaction
388 static int transaction_oob(struct tdb_context
*tdb
, tdb_off_t len
, int probe
)
390 if (len
<= tdb
->map_size
) {
393 tdb
->ecode
= TDB_ERR_IO
;
398 transaction version of tdb_expand().
400 static int transaction_expand_file(struct tdb_context
*tdb
, tdb_off_t size
,
403 /* add a write to the transaction elements, so subsequent
404 reads see the zero data */
405 if (transaction_write(tdb
, size
, NULL
, addition
) != 0) {
409 tdb
->transaction
->need_repack
= true;
415 brlock during a transaction - ignore them
417 static int transaction_brlock(struct tdb_context
*tdb
,
418 int rw_type
, tdb_off_t offset
, size_t len
,
419 enum tdb_lock_flags 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
->num_locks
!= 0 || tdb
->allrecord_lock
.count
) {
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_brlock(tdb
, F_RDLCK
, FREELIST_TOP
, 0, TDB_LOCK_WAIT
) == -1) {
506 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_start: failed to get hash locks\n"));
507 tdb
->ecode
= TDB_ERR_LOCK
;
511 /* setup a copy of the hash table heads so the hash scan in
512 traverse can be fast */
513 tdb
->transaction
->hash_heads
= (uint32_t *)
514 calloc(tdb
->header
.hash_size
+1, sizeof(uint32_t));
515 if (tdb
->transaction
->hash_heads
== NULL
) {
516 tdb
->ecode
= TDB_ERR_OOM
;
519 if (tdb
->methods
->tdb_read(tdb
, FREELIST_TOP
, tdb
->transaction
->hash_heads
,
520 TDB_HASHTABLE_SIZE(tdb
), 0) != 0) {
521 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_start: failed to read hash heads\n"));
522 tdb
->ecode
= TDB_ERR_IO
;
526 /* make sure we know about any file expansions already done by
528 tdb
->methods
->tdb_oob(tdb
, tdb
->map_size
+ 1, 1);
529 tdb
->transaction
->old_map_size
= tdb
->map_size
;
531 /* finally hook the io methods, replacing them with
532 transaction specific methods */
533 tdb
->transaction
->io_methods
= tdb
->methods
;
534 tdb
->methods
= &transaction_methods
;
536 /* Trace at the end, so we get sequence number correct. */
537 tdb_trace(tdb
, "tdb_transaction_start");
541 tdb_brunlock(tdb
, F_RDLCK
, FREELIST_TOP
, 0);
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 /* ltype is F_WRLCK after prepare. */
581 static int _tdb_transaction_cancel(struct tdb_context
*tdb
, int ltype
)
585 if (tdb
->transaction
== NULL
) {
586 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_cancel: no transaction\n"));
590 if (tdb
->transaction
->nesting
!= 0) {
591 tdb
->transaction
->transaction_error
= 1;
592 tdb
->transaction
->nesting
--;
596 tdb
->map_size
= tdb
->transaction
->old_map_size
;
598 /* free all the transaction blocks */
599 for (i
=0;i
<tdb
->transaction
->num_blocks
;i
++) {
600 if (tdb
->transaction
->blocks
[i
] != NULL
) {
601 free(tdb
->transaction
->blocks
[i
]);
604 SAFE_FREE(tdb
->transaction
->blocks
);
606 if (tdb
->transaction
->magic_offset
) {
607 const struct tdb_methods
*methods
= tdb
->transaction
->io_methods
;
608 const uint32_t invalid
= TDB_RECOVERY_INVALID_MAGIC
;
610 /* remove the recovery marker */
611 if (methods
->tdb_write(tdb
, tdb
->transaction
->magic_offset
, &invalid
, 4) == -1 ||
612 transaction_sync(tdb
, tdb
->transaction
->magic_offset
, 4) == -1) {
613 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_cancel: failed to remove recovery magic\n"));
618 if (tdb
->transaction
->open_lock_taken
) {
619 tdb_brunlock(tdb
, F_WRLCK
, OPEN_LOCK
, 1);
620 tdb
->transaction
->open_lock_taken
= false;
623 /* remove any global lock created during the transaction */
624 if (tdb
->allrecord_lock
.count
!= 0) {
625 tdb_brunlock(tdb
, tdb
->allrecord_lock
.ltype
,
626 FREELIST_TOP
, 4*tdb
->header
.hash_size
);
627 tdb
->allrecord_lock
.count
= 0;
630 /* remove any locks created during the transaction */
631 if (tdb
->num_locks
!= 0) {
632 for (i
=0;i
<tdb
->num_lockrecs
;i
++) {
633 tdb_brunlock(tdb
, tdb
->lockrecs
[i
].ltype
,
634 tdb
->lockrecs
[i
].off
, 1);
637 tdb
->num_lockrecs
= 0;
638 SAFE_FREE(tdb
->lockrecs
);
641 /* restore the normal io methods */
642 tdb
->methods
= tdb
->transaction
->io_methods
;
644 tdb_brunlock(tdb
, ltype
, FREELIST_TOP
, 0);
645 tdb_transaction_unlock(tdb
, F_WRLCK
);
646 SAFE_FREE(tdb
->transaction
->hash_heads
);
647 SAFE_FREE(tdb
->transaction
);
653 cancel the current transaction
655 int tdb_transaction_cancel(struct tdb_context
*tdb
)
658 tdb_trace(tdb
, "tdb_transaction_cancel");
659 if (tdb
->transaction
&& tdb
->transaction
->prepared
)
661 return _tdb_transaction_cancel(tdb
, ltype
);
665 work out how much space the linearised recovery data will consume
667 static tdb_len_t
tdb_recovery_size(struct tdb_context
*tdb
)
669 tdb_len_t recovery_size
= 0;
672 recovery_size
= sizeof(uint32_t);
673 for (i
=0;i
<tdb
->transaction
->num_blocks
;i
++) {
674 if (i
* tdb
->transaction
->block_size
>= tdb
->transaction
->old_map_size
) {
677 if (tdb
->transaction
->blocks
[i
] == NULL
) {
680 recovery_size
+= 2*sizeof(tdb_off_t
);
681 if (i
== tdb
->transaction
->num_blocks
-1) {
682 recovery_size
+= tdb
->transaction
->last_block_size
;
684 recovery_size
+= tdb
->transaction
->block_size
;
688 return recovery_size
;
692 allocate the recovery area, or use an existing recovery area if it is
695 static int tdb_recovery_allocate(struct tdb_context
*tdb
,
696 tdb_len_t
*recovery_size
,
697 tdb_off_t
*recovery_offset
,
698 tdb_len_t
*recovery_max_size
)
700 struct tdb_record rec
;
701 const struct tdb_methods
*methods
= tdb
->transaction
->io_methods
;
702 tdb_off_t recovery_head
;
704 if (tdb_ofs_read(tdb
, TDB_RECOVERY_HEAD
, &recovery_head
) == -1) {
705 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_recovery_allocate: failed to read recovery head\n"));
711 if (recovery_head
!= 0) {
712 if (methods
->tdb_read(tdb
, recovery_head
, &rec
, sizeof(rec
), DOCONV()) == -1) {
713 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_recovery_allocate: failed to read recovery record\n"));
716 /* ignore invalid recovery regions: can happen in crash */
717 if (rec
.magic
!= TDB_RECOVERY_MAGIC
&&
718 rec
.magic
!= TDB_RECOVERY_INVALID_MAGIC
) {
723 *recovery_size
= tdb_recovery_size(tdb
);
725 if (recovery_head
!= 0 && *recovery_size
<= rec
.rec_len
) {
726 /* it fits in the existing area */
727 *recovery_max_size
= rec
.rec_len
;
728 *recovery_offset
= recovery_head
;
732 /* we need to free up the old recovery area, then allocate a
733 new one at the end of the file. Note that we cannot use
734 tdb_allocate() to allocate the new one as that might return
735 us an area that is being currently used (as of the start of
737 if (recovery_head
!= 0) {
738 if (tdb_free(tdb
, recovery_head
, &rec
) == -1) {
739 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_recovery_allocate: failed to free previous recovery area\n"));
744 /* the tdb_free() call might have increased the recovery size */
745 *recovery_size
= tdb_recovery_size(tdb
);
747 /* round up to a multiple of page size */
748 *recovery_max_size
= TDB_ALIGN(sizeof(rec
) + *recovery_size
, tdb
->page_size
) - sizeof(rec
);
749 *recovery_offset
= tdb
->map_size
;
750 recovery_head
= *recovery_offset
;
752 if (methods
->tdb_expand_file(tdb
, tdb
->transaction
->old_map_size
,
753 (tdb
->map_size
- tdb
->transaction
->old_map_size
) +
754 sizeof(rec
) + *recovery_max_size
) == -1) {
755 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_recovery_allocate: failed to create recovery area\n"));
759 /* remap the file (if using mmap) */
760 methods
->tdb_oob(tdb
, tdb
->map_size
+ 1, 1);
762 /* we have to reset the old map size so that we don't try to expand the file
763 again in the transaction commit, which would destroy the recovery area */
764 tdb
->transaction
->old_map_size
= tdb
->map_size
;
766 /* write the recovery header offset and sync - we can sync without a race here
767 as the magic ptr in the recovery record has not been set */
768 CONVERT(recovery_head
);
769 if (methods
->tdb_write(tdb
, TDB_RECOVERY_HEAD
,
770 &recovery_head
, sizeof(tdb_off_t
)) == -1) {
771 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_recovery_allocate: failed to write recovery head\n"));
774 if (transaction_write_existing(tdb
, TDB_RECOVERY_HEAD
, &recovery_head
, sizeof(tdb_off_t
)) == -1) {
775 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_recovery_allocate: failed to write recovery head\n"));
784 setup the recovery data that will be used on a crash during commit
786 static int transaction_setup_recovery(struct tdb_context
*tdb
,
787 tdb_off_t
*magic_offset
)
789 tdb_len_t recovery_size
;
790 unsigned char *data
, *p
;
791 const struct tdb_methods
*methods
= tdb
->transaction
->io_methods
;
792 struct tdb_record
*rec
;
793 tdb_off_t recovery_offset
, recovery_max_size
;
794 tdb_off_t old_map_size
= tdb
->transaction
->old_map_size
;
795 uint32_t magic
, tailer
;
799 check that the recovery area has enough space
801 if (tdb_recovery_allocate(tdb
, &recovery_size
,
802 &recovery_offset
, &recovery_max_size
) == -1) {
806 data
= (unsigned char *)malloc(recovery_size
+ sizeof(*rec
));
808 tdb
->ecode
= TDB_ERR_OOM
;
812 rec
= (struct tdb_record
*)data
;
813 memset(rec
, 0, sizeof(*rec
));
815 rec
->magic
= TDB_RECOVERY_INVALID_MAGIC
;
816 rec
->data_len
= recovery_size
;
817 rec
->rec_len
= recovery_max_size
;
818 rec
->key_len
= old_map_size
;
821 /* build the recovery data into a single blob to allow us to do a single
822 large write, which should be more efficient */
823 p
= data
+ sizeof(*rec
);
824 for (i
=0;i
<tdb
->transaction
->num_blocks
;i
++) {
828 if (tdb
->transaction
->blocks
[i
] == NULL
) {
832 offset
= i
* tdb
->transaction
->block_size
;
833 length
= tdb
->transaction
->block_size
;
834 if (i
== tdb
->transaction
->num_blocks
-1) {
835 length
= tdb
->transaction
->last_block_size
;
838 if (offset
>= old_map_size
) {
841 if (offset
+ length
> tdb
->transaction
->old_map_size
) {
842 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
844 tdb
->ecode
= TDB_ERR_CORRUPT
;
847 memcpy(p
, &offset
, 4);
848 memcpy(p
+4, &length
, 4);
852 /* the recovery area contains the old data, not the
853 new data, so we have to call the original tdb_read
855 if (methods
->tdb_read(tdb
, offset
, p
+ 8, length
, 0) != 0) {
857 tdb
->ecode
= TDB_ERR_IO
;
864 tailer
= sizeof(*rec
) + recovery_max_size
;
865 memcpy(p
, &tailer
, 4);
868 /* write the recovery data to the recovery area */
869 if (methods
->tdb_write(tdb
, recovery_offset
, data
, sizeof(*rec
) + recovery_size
) == -1) {
870 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
872 tdb
->ecode
= TDB_ERR_IO
;
875 if (transaction_write_existing(tdb
, recovery_offset
, data
, sizeof(*rec
) + recovery_size
) == -1) {
876 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
878 tdb
->ecode
= TDB_ERR_IO
;
882 /* as we don't have ordered writes, we have to sync the recovery
883 data before we update the magic to indicate that the recovery
885 if (transaction_sync(tdb
, recovery_offset
, sizeof(*rec
) + recovery_size
) == -1) {
892 magic
= TDB_RECOVERY_MAGIC
;
895 *magic_offset
= recovery_offset
+ offsetof(struct tdb_record
, magic
);
897 if (methods
->tdb_write(tdb
, *magic_offset
, &magic
, sizeof(magic
)) == -1) {
898 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
899 tdb
->ecode
= TDB_ERR_IO
;
902 if (transaction_write_existing(tdb
, *magic_offset
, &magic
, sizeof(magic
)) == -1) {
903 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
904 tdb
->ecode
= TDB_ERR_IO
;
908 /* ensure the recovery magic marker is on disk */
909 if (transaction_sync(tdb
, *magic_offset
, sizeof(magic
)) == -1) {
916 static int _tdb_transaction_prepare_commit(struct tdb_context
*tdb
)
918 const struct tdb_methods
*methods
;
920 if (tdb
->transaction
== NULL
) {
921 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_prepare_commit: no transaction\n"));
925 if (tdb
->transaction
->prepared
) {
926 tdb
->ecode
= TDB_ERR_EINVAL
;
927 _tdb_transaction_cancel(tdb
, F_WRLCK
);
928 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_prepare_commit: transaction already prepared\n"));
932 if (tdb
->transaction
->transaction_error
) {
933 tdb
->ecode
= TDB_ERR_IO
;
934 _tdb_transaction_cancel(tdb
, F_RDLCK
);
935 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_prepare_commit: transaction error pending\n"));
940 if (tdb
->transaction
->nesting
!= 0) {
944 /* check for a null transaction */
945 if (tdb
->transaction
->blocks
== NULL
) {
949 methods
= tdb
->transaction
->io_methods
;
951 /* if there are any locks pending then the caller has not
952 nested their locks properly, so fail the transaction */
953 if (tdb
->num_locks
|| tdb
->allrecord_lock
.count
) {
954 tdb
->ecode
= TDB_ERR_LOCK
;
955 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_prepare_commit: locks pending on commit\n"));
956 _tdb_transaction_cancel(tdb
, F_RDLCK
);
960 /* upgrade the main transaction lock region to a write lock */
961 if (tdb_brlock_upgrade(tdb
, FREELIST_TOP
, 0) == -1) {
962 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
963 tdb
->ecode
= TDB_ERR_LOCK
;
964 _tdb_transaction_cancel(tdb
, F_RDLCK
);
968 /* get the open lock - this prevents new users attaching to the database
970 if (tdb_brlock(tdb
, F_WRLCK
, OPEN_LOCK
, 1, TDB_LOCK_WAIT
) == -1) {
971 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_prepare_commit: failed to get open lock\n"));
972 tdb
->ecode
= TDB_ERR_LOCK
;
973 _tdb_transaction_cancel(tdb
, F_WRLCK
);
977 tdb
->transaction
->open_lock_taken
= true;
979 if (!(tdb
->flags
& TDB_NOSYNC
)) {
980 /* write the recovery data to the end of the file */
981 if (transaction_setup_recovery(tdb
, &tdb
->transaction
->magic_offset
) == -1) {
982 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
983 _tdb_transaction_cancel(tdb
, F_WRLCK
);
988 tdb
->transaction
->prepared
= true;
990 /* expand the file to the new size if needed */
991 if (tdb
->map_size
!= tdb
->transaction
->old_map_size
) {
992 if (methods
->tdb_expand_file(tdb
, tdb
->transaction
->old_map_size
,
994 tdb
->transaction
->old_map_size
) == -1) {
995 tdb
->ecode
= TDB_ERR_IO
;
996 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_prepare_commit: expansion failed\n"));
997 _tdb_transaction_cancel(tdb
, F_WRLCK
);
1000 tdb
->map_size
= tdb
->transaction
->old_map_size
;
1001 methods
->tdb_oob(tdb
, tdb
->map_size
+ 1, 1);
1004 /* Keep the open lock until the actual commit */
1010 prepare to commit the current transaction
1012 int tdb_transaction_prepare_commit(struct tdb_context
*tdb
)
1014 tdb_trace(tdb
, "tdb_transaction_prepare_commit");
1015 return _tdb_transaction_prepare_commit(tdb
);
1019 commit the current transaction
1021 int tdb_transaction_commit(struct tdb_context
*tdb
)
1023 const struct tdb_methods
*methods
;
1027 if (tdb
->transaction
== NULL
) {
1028 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_commit: no transaction\n"));
1032 tdb_trace(tdb
, "tdb_transaction_commit");
1034 if (tdb
->transaction
->transaction_error
) {
1035 tdb
->ecode
= TDB_ERR_IO
;
1036 _tdb_transaction_cancel(tdb
, F_RDLCK
);
1037 TDB_LOG((tdb
, TDB_DEBUG_ERROR
, "tdb_transaction_commit: transaction error pending\n"));
1042 if (tdb
->transaction
->nesting
!= 0) {
1043 tdb
->transaction
->nesting
--;
1047 /* check for a null transaction */
1048 if (tdb
->transaction
->blocks
== NULL
) {
1049 _tdb_transaction_cancel(tdb
, F_RDLCK
);
1053 if (!tdb
->transaction
->prepared
) {
1054 int ret
= _tdb_transaction_prepare_commit(tdb
);
1059 methods
= tdb
->transaction
->io_methods
;
1061 /* perform all the writes */
1062 for (i
=0;i
<tdb
->transaction
->num_blocks
;i
++) {
1066 if (tdb
->transaction
->blocks
[i
] == NULL
) {
1070 offset
= i
* tdb
->transaction
->block_size
;
1071 length
= tdb
->transaction
->block_size
;
1072 if (i
== tdb
->transaction
->num_blocks
-1) {
1073 length
= tdb
->transaction
->last_block_size
;
1076 if (methods
->tdb_write(tdb
, offset
, tdb
->transaction
->blocks
[i
], length
) == -1) {
1077 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_commit: write failed during commit\n"));
1079 /* we've overwritten part of the data and
1080 possibly expanded the file, so we need to
1081 run the crash recovery code */
1082 tdb
->methods
= methods
;
1083 tdb_transaction_recover(tdb
);
1085 _tdb_transaction_cancel(tdb
, F_WRLCK
);
1087 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_commit: write failed\n"));
1090 SAFE_FREE(tdb
->transaction
->blocks
[i
]);
1093 SAFE_FREE(tdb
->transaction
->blocks
);
1094 tdb
->transaction
->num_blocks
= 0;
1096 /* ensure the new data is on disk */
1097 if (transaction_sync(tdb
, 0, tdb
->map_size
) == -1) {
1102 TODO: maybe write to some dummy hdr field, or write to magic
1103 offset without mmap, before the last sync, instead of the
1107 /* on some systems (like Linux 2.6.x) changes via mmap/msync
1108 don't change the mtime of the file, this means the file may
1109 not be backed up (as tdb rounding to block sizes means that
1110 file size changes are quite rare too). The following forces
1111 mtime changes when a transaction completes */
1113 utime(tdb
->name
, NULL
);
1116 need_repack
= tdb
->transaction
->need_repack
;
1118 /* use a transaction cancel to free memory and remove the
1119 transaction locks */
1120 _tdb_transaction_cancel(tdb
, F_WRLCK
);
1123 return tdb_repack(tdb
);
1131 recover from an aborted transaction. Must be called with exclusive
1132 database write access already established (including the open
1133 lock to prevent new processes attaching)
1135 int tdb_transaction_recover(struct tdb_context
*tdb
)
1137 tdb_off_t recovery_head
, recovery_eof
;
1138 unsigned char *data
, *p
;
1140 struct tdb_record rec
;
1142 /* find the recovery area */
1143 if (tdb_ofs_read(tdb
, TDB_RECOVERY_HEAD
, &recovery_head
) == -1) {
1144 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to read recovery head\n"));
1145 tdb
->ecode
= TDB_ERR_IO
;
1149 if (recovery_head
== 0) {
1150 /* we have never allocated a recovery record */
1154 /* read the recovery record */
1155 if (tdb
->methods
->tdb_read(tdb
, recovery_head
, &rec
,
1156 sizeof(rec
), DOCONV()) == -1) {
1157 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to read recovery record\n"));
1158 tdb
->ecode
= TDB_ERR_IO
;
1162 if (rec
.magic
!= TDB_RECOVERY_MAGIC
) {
1163 /* there is no valid recovery data */
1167 if (tdb
->read_only
) {
1168 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: attempt to recover read only database\n"));
1169 tdb
->ecode
= TDB_ERR_CORRUPT
;
1173 recovery_eof
= rec
.key_len
;
1175 data
= (unsigned char *)malloc(rec
.data_len
);
1177 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to allocate recovery data\n"));
1178 tdb
->ecode
= TDB_ERR_OOM
;
1182 /* read the full recovery data */
1183 if (tdb
->methods
->tdb_read(tdb
, recovery_head
+ sizeof(rec
), data
,
1184 rec
.data_len
, 0) == -1) {
1185 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to read recovery data\n"));
1186 tdb
->ecode
= TDB_ERR_IO
;
1190 /* recover the file data */
1192 while (p
+8 < data
+ rec
.data_len
) {
1198 memcpy(&len
, p
+4, 4);
1200 if (tdb
->methods
->tdb_write(tdb
, ofs
, p
+8, len
) == -1) {
1202 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len
, ofs
));
1203 tdb
->ecode
= TDB_ERR_IO
;
1211 if (transaction_sync(tdb
, 0, tdb
->map_size
) == -1) {
1212 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to sync recovery\n"));
1213 tdb
->ecode
= TDB_ERR_IO
;
1217 /* if the recovery area is after the recovered eof then remove it */
1218 if (recovery_eof
<= recovery_head
) {
1219 if (tdb_ofs_write(tdb
, TDB_RECOVERY_HEAD
, &zero
) == -1) {
1220 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to remove recovery head\n"));
1221 tdb
->ecode
= TDB_ERR_IO
;
1226 /* remove the recovery magic */
1227 if (tdb_ofs_write(tdb
, recovery_head
+ offsetof(struct tdb_record
, magic
),
1229 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to remove recovery magic\n"));
1230 tdb
->ecode
= TDB_ERR_IO
;
1234 /* reduce the file size to the old size */
1236 if (ftruncate(tdb
->fd
, recovery_eof
) != 0) {
1237 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1238 tdb
->ecode
= TDB_ERR_IO
;
1241 tdb
->map_size
= recovery_eof
;
1244 if (transaction_sync(tdb
, 0, recovery_eof
) == -1) {
1245 TDB_LOG((tdb
, TDB_DEBUG_FATAL
, "tdb_transaction_recover: failed to sync2 recovery\n"));
1246 tdb
->ecode
= TDB_ERR_IO
;
1250 TDB_LOG((tdb
, TDB_DEBUG_TRACE
, "tdb_transaction_recover: recovered %d byte database\n",