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Diffstat (limited to 'tdb/common/transaction.c')
| -rw-r--r-- | tdb/common/transaction.c | 1119 |
1 files changed, 0 insertions, 1119 deletions
diff --git a/tdb/common/transaction.c b/tdb/common/transaction.c deleted file mode 100644 index 7acda640c..000000000 --- a/tdb/common/transaction.c +++ /dev/null @@ -1,1119 +0,0 @@ - /* - Unix SMB/CIFS implementation. - - trivial database library - - Copyright (C) Andrew Tridgell 2005 - - ** NOTE! The following LGPL license applies to the tdb - ** library. This does NOT imply that all of Samba is released - ** under the LGPL - - This library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 3 of the License, or (at your option) any later version. - - This library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with this library; if not, see <http://www.gnu.org/licenses/>. -*/ - -#include "tdb_private.h" - -/* - transaction design: - - - only allow a single transaction at a time per database. This makes - using the transaction API simpler, as otherwise the caller would - have to cope with temporary failures in transactions that conflict - with other current transactions - - - keep the transaction recovery information in the same file as the - database, using a special 'transaction recovery' record pointed at - by the header. This removes the need for extra journal files as - used by some other databases - - - dynamically allocated the transaction recover record, re-using it - for subsequent transactions. If a larger record is needed then - tdb_free() the old record to place it on the normal tdb freelist - before allocating the new record - - - during transactions, keep a linked list of writes all that have - been performed by intercepting all tdb_write() calls. The hooked - transaction versions of tdb_read() and tdb_write() check this - linked list and try to use the elements of the list in preference - to the real database. - - - don't allow any locks to be held when a transaction starts, - otherwise we can end up with deadlock (plus lack of lock nesting - in posix locks would mean the lock is lost) - - - if the caller gains a lock during the transaction but doesn't - release it then fail the commit - - - allow for nested calls to tdb_transaction_start(), re-using the - existing transaction record. If the inner transaction is cancelled - then a subsequent commit will fail - - - keep a mirrored copy of the tdb hash chain heads to allow for the - fast hash heads scan on traverse, updating the mirrored copy in - the transaction version of tdb_write - - - allow callers to mix transaction and non-transaction use of tdb, - although once a transaction is started then an exclusive lock is - gained until the transaction is committed or cancelled - - - the commit stategy involves first saving away all modified data - into a linearised buffer in the transaction recovery area, then - marking the transaction recovery area with a magic value to - indicate a valid recovery record. In total 4 fsync/msync calls are - needed per commit to prevent race conditions. It might be possible - to reduce this to 3 or even 2 with some more work. - - - check for a valid recovery record on open of the tdb, while the - global lock is held. Automatically recover from the transaction - recovery area if needed, then continue with the open as - usual. This allows for smooth crash recovery with no administrator - intervention. - - - if TDB_NOSYNC is passed to flags in tdb_open then transactions are - still available, but no transaction recovery area is used and no - fsync/msync calls are made. - -*/ - - -/* - hold the context of any current transaction -*/ -struct tdb_transaction { - /* we keep a mirrored copy of the tdb hash heads here so - tdb_next_hash_chain() can operate efficiently */ - uint32_t *hash_heads; - - /* the original io methods - used to do IOs to the real db */ - const struct tdb_methods *io_methods; - - /* the list of transaction blocks. When a block is first - written to, it gets created in this list */ - uint8_t **blocks; - uint32_t num_blocks; - uint32_t block_size; /* bytes in each block */ - uint32_t last_block_size; /* number of valid bytes in the last block */ - - /* non-zero when an internal transaction error has - occurred. All write operations will then fail until the - transaction is ended */ - int transaction_error; - - /* when inside a transaction we need to keep track of any - nested tdb_transaction_start() calls, as these are allowed, - but don't create a new transaction */ - int nesting; - - /* old file size before transaction */ - tdb_len_t old_map_size; -}; - - -/* - read while in a transaction. We need to check first if the data is in our list - of transaction elements, then if not do a real read -*/ -static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf, - tdb_len_t len, int cv) -{ - uint32_t blk; - - /* break it down into block sized ops */ - while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) { - tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size); - if (transaction_read(tdb, off, buf, len2, cv) != 0) { - return -1; - } - len -= len2; - off += len2; - buf = (void *)(len2 + (char *)buf); - } - - if (len == 0) { - return 0; - } - - blk = off / tdb->transaction->block_size; - - /* see if we have it in the block list */ - if (tdb->transaction->num_blocks <= blk || - tdb->transaction->blocks[blk] == NULL) { - /* nope, do a real read */ - if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) { - goto fail; - } - return 0; - } - - /* it is in the block list. Now check for the last block */ - if (blk == tdb->transaction->num_blocks-1) { - if (len > tdb->transaction->last_block_size) { - goto fail; - } - } - - /* now copy it out of this block */ - memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len); - if (cv) { - tdb_convert(buf, len); - } - return 0; - -fail: - TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len)); - tdb->ecode = TDB_ERR_IO; - tdb->transaction->transaction_error = 1; - return -1; -} - - -/* - write while in a transaction -*/ -static int transaction_write(struct tdb_context *tdb, tdb_off_t off, - const void *buf, tdb_len_t len) -{ - uint32_t blk; - - /* if the write is to a hash head, then update the transaction - hash heads */ - if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP && - off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) { - uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t); - memcpy(&tdb->transaction->hash_heads[chain], buf, len); - } - - /* break it up into block sized chunks */ - while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) { - tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size); - if (transaction_write(tdb, off, buf, len2) != 0) { - return -1; - } - len -= len2; - off += len2; - if (buf != NULL) { - buf = (const void *)(len2 + (const char *)buf); - } - } - - if (len == 0) { - return 0; - } - - blk = off / tdb->transaction->block_size; - off = off % tdb->transaction->block_size; - - if (tdb->transaction->num_blocks <= blk) { - uint8_t **new_blocks; - /* expand the blocks array */ - if (tdb->transaction->blocks == NULL) { - new_blocks = (uint8_t **)malloc( - (blk+1)*sizeof(uint8_t *)); - } else { - new_blocks = (uint8_t **)realloc( - tdb->transaction->blocks, - (blk+1)*sizeof(uint8_t *)); - } - if (new_blocks == NULL) { - tdb->ecode = TDB_ERR_OOM; - goto fail; - } - memset(&new_blocks[tdb->transaction->num_blocks], 0, - (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *)); - tdb->transaction->blocks = new_blocks; - tdb->transaction->num_blocks = blk+1; - tdb->transaction->last_block_size = 0; - } - - /* allocate and fill a block? */ - if (tdb->transaction->blocks[blk] == NULL) { - tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1); - if (tdb->transaction->blocks[blk] == NULL) { - tdb->ecode = TDB_ERR_OOM; - tdb->transaction->transaction_error = 1; - return -1; - } - if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) { - tdb_len_t len2 = tdb->transaction->block_size; - if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) { - len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size); - } - if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size, - tdb->transaction->blocks[blk], - len2, 0) != 0) { - SAFE_FREE(tdb->transaction->blocks[blk]); - tdb->ecode = TDB_ERR_IO; - goto fail; - } - if (blk == tdb->transaction->num_blocks-1) { - tdb->transaction->last_block_size = len2; - } - } - } - - /* overwrite part of an existing block */ - if (buf == NULL) { - memset(tdb->transaction->blocks[blk] + off, 0, len); - } else { - memcpy(tdb->transaction->blocks[blk] + off, buf, len); - } - if (blk == tdb->transaction->num_blocks-1) { - if (len + off > tdb->transaction->last_block_size) { - tdb->transaction->last_block_size = len + off; - } - } - - return 0; - -fail: - TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n", - (blk*tdb->transaction->block_size) + off, len)); - tdb->transaction->transaction_error = 1; - return -1; -} - - -/* - write while in a transaction - this varient never expands the transaction blocks, it only - updates existing blocks. This means it cannot change the recovery size -*/ -static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off, - const void *buf, tdb_len_t len) -{ - uint32_t blk; - - /* break it up into block sized chunks */ - while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) { - tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size); - if (transaction_write_existing(tdb, off, buf, len2) != 0) { - return -1; - } - len -= len2; - off += len2; - if (buf != NULL) { - buf = (const void *)(len2 + (const char *)buf); - } - } - - if (len == 0) { - return 0; - } - - blk = off / tdb->transaction->block_size; - off = off % tdb->transaction->block_size; - - if (tdb->transaction->num_blocks <= blk || - tdb->transaction->blocks[blk] == NULL) { - return 0; - } - - if (blk == tdb->transaction->num_blocks-1 && - off + len > tdb->transaction->last_block_size) { - if (off >= tdb->transaction->last_block_size) { - return 0; - } - len = tdb->transaction->last_block_size - off; - } - - /* overwrite part of an existing block */ - memcpy(tdb->transaction->blocks[blk] + off, buf, len); - - return 0; -} - - -/* - accelerated hash chain head search, using the cached hash heads -*/ -static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain) -{ - uint32_t h = *chain; - for (;h < tdb->header.hash_size;h++) { - /* the +1 takes account of the freelist */ - if (0 != tdb->transaction->hash_heads[h+1]) { - break; - } - } - (*chain) = h; -} - -/* - out of bounds check during a transaction -*/ -static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe) -{ - if (len <= tdb->map_size) { - return 0; - } - return TDB_ERRCODE(TDB_ERR_IO, -1); -} - -/* - transaction version of tdb_expand(). -*/ -static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size, - tdb_off_t addition) -{ - /* add a write to the transaction elements, so subsequent - reads see the zero data */ - if (transaction_write(tdb, size, NULL, addition) != 0) { - return -1; - } - - return 0; -} - -/* - brlock during a transaction - ignore them -*/ -static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset, - int rw_type, int lck_type, int probe, size_t len) -{ - return 0; -} - -static const struct tdb_methods transaction_methods = { - transaction_read, - transaction_write, - transaction_next_hash_chain, - transaction_oob, - transaction_expand_file, - transaction_brlock -}; - - -/* - start a tdb transaction. No token is returned, as only a single - transaction is allowed to be pending per tdb_context -*/ -int tdb_transaction_start(struct tdb_context *tdb) -{ - /* some sanity checks */ - if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) { - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n")); - tdb->ecode = TDB_ERR_EINVAL; - return -1; - } - - /* cope with nested tdb_transaction_start() calls */ - if (tdb->transaction != NULL) { - tdb->transaction->nesting++; - TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", - tdb->transaction->nesting)); - return 0; - } - - if (tdb->num_locks != 0 || tdb->global_lock.count) { - /* the caller must not have any locks when starting a - transaction as otherwise we'll be screwed by lack - of nested locks in posix */ - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n")); - tdb->ecode = TDB_ERR_LOCK; - return -1; - } - - if (tdb->travlocks.next != NULL) { - /* you cannot use transactions inside a traverse (although you can use - traverse inside a transaction) as otherwise you can end up with - deadlock */ - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n")); - tdb->ecode = TDB_ERR_LOCK; - return -1; - } - - tdb->transaction = (struct tdb_transaction *) - calloc(sizeof(struct tdb_transaction), 1); - if (tdb->transaction == NULL) { - tdb->ecode = TDB_ERR_OOM; - return -1; - } - - /* a page at a time seems like a reasonable compromise between compactness and efficiency */ - tdb->transaction->block_size = tdb->page_size; - - /* get the transaction write lock. This is a blocking lock. As - discussed with Volker, there are a number of ways we could - make this async, which we will probably do in the future */ - if (tdb_transaction_lock(tdb, F_WRLCK) == -1) { - SAFE_FREE(tdb->transaction->blocks); - SAFE_FREE(tdb->transaction); - return -1; - } - - /* get a read lock from the freelist to the end of file. This - is upgraded to a write lock during the commit */ - if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) { - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n")); - tdb->ecode = TDB_ERR_LOCK; - goto fail; - } - - /* setup a copy of the hash table heads so the hash scan in - traverse can be fast */ - tdb->transaction->hash_heads = (uint32_t *) - calloc(tdb->header.hash_size+1, sizeof(uint32_t)); - if (tdb->transaction->hash_heads == NULL) { - tdb->ecode = TDB_ERR_OOM; - goto fail; - } - if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads, - TDB_HASHTABLE_SIZE(tdb), 0) != 0) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n")); - tdb->ecode = TDB_ERR_IO; - goto fail; - } - - /* make sure we know about any file expansions already done by - anyone else */ - tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1); - tdb->transaction->old_map_size = tdb->map_size; - - /* finally hook the io methods, replacing them with - transaction specific methods */ - tdb->transaction->io_methods = tdb->methods; - tdb->methods = &transaction_methods; - - return 0; - -fail: - tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0); - tdb_transaction_unlock(tdb); - SAFE_FREE(tdb->transaction->blocks); - SAFE_FREE(tdb->transaction->hash_heads); - SAFE_FREE(tdb->transaction); - return -1; -} - - -/* - cancel the current transaction -*/ -int tdb_transaction_cancel(struct tdb_context *tdb) -{ - int i; - - if (tdb->transaction == NULL) { - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n")); - return -1; - } - - if (tdb->transaction->nesting != 0) { - tdb->transaction->transaction_error = 1; - tdb->transaction->nesting--; - return 0; - } - - tdb->map_size = tdb->transaction->old_map_size; - - /* free all the transaction blocks */ - for (i=0;i<tdb->transaction->num_blocks;i++) { - if (tdb->transaction->blocks[i] != NULL) { - free(tdb->transaction->blocks[i]); - } - } - SAFE_FREE(tdb->transaction->blocks); - - /* remove any global lock created during the transaction */ - if (tdb->global_lock.count != 0) { - tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size); - tdb->global_lock.count = 0; - } - - /* remove any locks created during the transaction */ - if (tdb->num_locks != 0) { - for (i=0;i<tdb->num_lockrecs;i++) { - tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list, - F_UNLCK,F_SETLKW, 0, 1); - } - tdb->num_locks = 0; - tdb->num_lockrecs = 0; - SAFE_FREE(tdb->lockrecs); - } - - /* restore the normal io methods */ - tdb->methods = tdb->transaction->io_methods; - - tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0); - tdb_transaction_unlock(tdb); - SAFE_FREE(tdb->transaction->hash_heads); - SAFE_FREE(tdb->transaction); - - return 0; -} - -/* - sync to disk -*/ -static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length) -{ - if (fsync(tdb->fd) != 0) { - tdb->ecode = TDB_ERR_IO; - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n")); - return -1; - } -#ifdef HAVE_MMAP - if (tdb->map_ptr) { - tdb_off_t moffset = offset & ~(tdb->page_size-1); - if (msync(moffset + (char *)tdb->map_ptr, - length + (offset - moffset), MS_SYNC) != 0) { - tdb->ecode = TDB_ERR_IO; - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n", - strerror(errno))); - return -1; - } - } -#endif - return 0; -} - - -/* - work out how much space the linearised recovery data will consume -*/ -static tdb_len_t tdb_recovery_size(struct tdb_context *tdb) -{ - tdb_len_t recovery_size = 0; - int i; - - recovery_size = sizeof(uint32_t); - for (i=0;i<tdb->transaction->num_blocks;i++) { - if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) { - break; - } - if (tdb->transaction->blocks[i] == NULL) { - continue; - } - recovery_size += 2*sizeof(tdb_off_t); - if (i == tdb->transaction->num_blocks-1) { - recovery_size += tdb->transaction->last_block_size; - } else { - recovery_size += tdb->transaction->block_size; - } - } - - return recovery_size; -} - -/* - allocate the recovery area, or use an existing recovery area if it is - large enough -*/ -static int tdb_recovery_allocate(struct tdb_context *tdb, - tdb_len_t *recovery_size, - tdb_off_t *recovery_offset, - tdb_len_t *recovery_max_size) -{ - struct list_struct rec; - const struct tdb_methods *methods = tdb->transaction->io_methods; - tdb_off_t recovery_head; - - if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n")); - return -1; - } - - rec.rec_len = 0; - - if (recovery_head != 0 && - methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n")); - return -1; - } - - *recovery_size = tdb_recovery_size(tdb); - - if (recovery_head != 0 && *recovery_size <= rec.rec_len) { - /* it fits in the existing area */ - *recovery_max_size = rec.rec_len; - *recovery_offset = recovery_head; - return 0; - } - - /* we need to free up the old recovery area, then allocate a - new one at the end of the file. Note that we cannot use - tdb_allocate() to allocate the new one as that might return - us an area that is being currently used (as of the start of - the transaction) */ - if (recovery_head != 0) { - if (tdb_free(tdb, recovery_head, &rec) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n")); - return -1; - } - } - - /* the tdb_free() call might have increased the recovery size */ - *recovery_size = tdb_recovery_size(tdb); - - /* round up to a multiple of page size */ - *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec); - *recovery_offset = tdb->map_size; - recovery_head = *recovery_offset; - - if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size, - (tdb->map_size - tdb->transaction->old_map_size) + - sizeof(rec) + *recovery_max_size) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n")); - return -1; - } - - /* remap the file (if using mmap) */ - methods->tdb_oob(tdb, tdb->map_size + 1, 1); - - /* we have to reset the old map size so that we don't try to expand the file - again in the transaction commit, which would destroy the recovery area */ - tdb->transaction->old_map_size = tdb->map_size; - - /* write the recovery header offset and sync - we can sync without a race here - as the magic ptr in the recovery record has not been set */ - CONVERT(recovery_head); - if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD, - &recovery_head, sizeof(tdb_off_t)) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n")); - return -1; - } - if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n")); - return -1; - } - - return 0; -} - - -/* - setup the recovery data that will be used on a crash during commit -*/ -static int transaction_setup_recovery(struct tdb_context *tdb, - tdb_off_t *magic_offset) -{ - tdb_len_t recovery_size; - unsigned char *data, *p; - const struct tdb_methods *methods = tdb->transaction->io_methods; - struct list_struct *rec; - tdb_off_t recovery_offset, recovery_max_size; - tdb_off_t old_map_size = tdb->transaction->old_map_size; - uint32_t magic, tailer; - int i; - - /* - check that the recovery area has enough space - */ - if (tdb_recovery_allocate(tdb, &recovery_size, - &recovery_offset, &recovery_max_size) == -1) { - return -1; - } - - data = (unsigned char *)malloc(recovery_size + sizeof(*rec)); - if (data == NULL) { - tdb->ecode = TDB_ERR_OOM; - return -1; - } - - rec = (struct list_struct *)data; - memset(rec, 0, sizeof(*rec)); - - rec->magic = 0; - rec->data_len = recovery_size; - rec->rec_len = recovery_max_size; - rec->key_len = old_map_size; - CONVERT(rec); - - /* build the recovery data into a single blob to allow us to do a single - large write, which should be more efficient */ - p = data + sizeof(*rec); - for (i=0;i<tdb->transaction->num_blocks;i++) { - tdb_off_t offset; - tdb_len_t length; - - if (tdb->transaction->blocks[i] == NULL) { - continue; - } - - offset = i * tdb->transaction->block_size; - length = tdb->transaction->block_size; - if (i == tdb->transaction->num_blocks-1) { - length = tdb->transaction->last_block_size; - } - - if (offset >= old_map_size) { - continue; - } - if (offset + length > tdb->transaction->old_map_size) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n")); - free(data); - tdb->ecode = TDB_ERR_CORRUPT; - return -1; - } - memcpy(p, &offset, 4); - memcpy(p+4, &length, 4); - if (DOCONV()) { - tdb_convert(p, 8); - } - /* the recovery area contains the old data, not the - new data, so we have to call the original tdb_read - method to get it */ - if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) { - free(data); - tdb->ecode = TDB_ERR_IO; - return -1; - } - p += 8 + length; - } - - /* and the tailer */ - tailer = sizeof(*rec) + recovery_max_size; - memcpy(p, &tailer, 4); - CONVERT(p); - - /* write the recovery data to the recovery area */ - if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n")); - free(data); - tdb->ecode = TDB_ERR_IO; - return -1; - } - if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n")); - free(data); - tdb->ecode = TDB_ERR_IO; - return -1; - } - - /* as we don't have ordered writes, we have to sync the recovery - data before we update the magic to indicate that the recovery - data is present */ - if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) { - free(data); - return -1; - } - - free(data); - - magic = TDB_RECOVERY_MAGIC; - CONVERT(magic); - - *magic_offset = recovery_offset + offsetof(struct list_struct, magic); - - if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - - /* ensure the recovery magic marker is on disk */ - if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) { - return -1; - } - - return 0; -} - -/* - commit the current transaction -*/ -int tdb_transaction_commit(struct tdb_context *tdb) -{ - const struct tdb_methods *methods; - tdb_off_t magic_offset = 0; - uint32_t zero = 0; - int i; - - if (tdb->transaction == NULL) { - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n")); - return -1; - } - - if (tdb->transaction->transaction_error) { - tdb->ecode = TDB_ERR_IO; - tdb_transaction_cancel(tdb); - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n")); - return -1; - } - - - if (tdb->transaction->nesting != 0) { - tdb->transaction->nesting--; - return 0; - } - - /* check for a null transaction */ - if (tdb->transaction->blocks == NULL) { - tdb_transaction_cancel(tdb); - return 0; - } - - methods = tdb->transaction->io_methods; - - /* if there are any locks pending then the caller has not - nested their locks properly, so fail the transaction */ - if (tdb->num_locks || tdb->global_lock.count) { - tdb->ecode = TDB_ERR_LOCK; - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: locks pending on commit\n")); - tdb_transaction_cancel(tdb); - return -1; - } - - /* upgrade the main transaction lock region to a write lock */ - if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) { - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to upgrade hash locks\n")); - tdb->ecode = TDB_ERR_LOCK; - tdb_transaction_cancel(tdb); - return -1; - } - - /* get the global lock - this prevents new users attaching to the database - during the commit */ - if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) { - TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: failed to get global lock\n")); - tdb->ecode = TDB_ERR_LOCK; - tdb_transaction_cancel(tdb); - return -1; - } - - if (!(tdb->flags & TDB_NOSYNC)) { - /* write the recovery data to the end of the file */ - if (transaction_setup_recovery(tdb, &magic_offset) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to setup recovery data\n")); - tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); - tdb_transaction_cancel(tdb); - return -1; - } - } - - /* expand the file to the new size if needed */ - if (tdb->map_size != tdb->transaction->old_map_size) { - if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size, - tdb->map_size - - tdb->transaction->old_map_size) == -1) { - tdb->ecode = TDB_ERR_IO; - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: expansion failed\n")); - tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); - tdb_transaction_cancel(tdb); - return -1; - } - tdb->map_size = tdb->transaction->old_map_size; - methods->tdb_oob(tdb, tdb->map_size + 1, 1); - } - - /* perform all the writes */ - for (i=0;i<tdb->transaction->num_blocks;i++) { - tdb_off_t offset; - tdb_len_t length; - - if (tdb->transaction->blocks[i] == NULL) { - continue; - } - - offset = i * tdb->transaction->block_size; - length = tdb->transaction->block_size; - if (i == tdb->transaction->num_blocks-1) { - length = tdb->transaction->last_block_size; - } - - if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n")); - - /* we've overwritten part of the data and - possibly expanded the file, so we need to - run the crash recovery code */ - tdb->methods = methods; - tdb_transaction_recover(tdb); - - tdb_transaction_cancel(tdb); - tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); - - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n")); - return -1; - } - SAFE_FREE(tdb->transaction->blocks[i]); - } - - SAFE_FREE(tdb->transaction->blocks); - tdb->transaction->num_blocks = 0; - - if (!(tdb->flags & TDB_NOSYNC)) { - /* ensure the new data is on disk */ - if (transaction_sync(tdb, 0, tdb->map_size) == -1) { - return -1; - } - - /* remove the recovery marker */ - if (methods->tdb_write(tdb, magic_offset, &zero, 4) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: failed to remove recovery magic\n")); - return -1; - } - - /* ensure the recovery marker has been removed on disk */ - if (transaction_sync(tdb, magic_offset, 4) == -1) { - return -1; - } - } - - tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1); - - /* - TODO: maybe write to some dummy hdr field, or write to magic - offset without mmap, before the last sync, instead of the - utime() call - */ - - /* on some systems (like Linux 2.6.x) changes via mmap/msync - don't change the mtime of the file, this means the file may - not be backed up (as tdb rounding to block sizes means that - file size changes are quite rare too). The following forces - mtime changes when a transaction completes */ -#ifdef HAVE_UTIME - utime(tdb->name, NULL); -#endif - - /* use a transaction cancel to free memory and remove the - transaction locks */ - tdb_transaction_cancel(tdb); - - return 0; -} - - -/* - recover from an aborted transaction. Must be called with exclusive - database write access already established (including the global - lock to prevent new processes attaching) -*/ -int tdb_transaction_recover(struct tdb_context *tdb) -{ - tdb_off_t recovery_head, recovery_eof; - unsigned char *data, *p; - uint32_t zero = 0; - struct list_struct rec; - - /* find the recovery area */ - if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - - if (recovery_head == 0) { - /* we have never allocated a recovery record */ - return 0; - } - - /* read the recovery record */ - if (tdb->methods->tdb_read(tdb, recovery_head, &rec, - sizeof(rec), DOCONV()) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - - if (rec.magic != TDB_RECOVERY_MAGIC) { - /* there is no valid recovery data */ - return 0; - } - - if (tdb->read_only) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n")); - tdb->ecode = TDB_ERR_CORRUPT; - return -1; - } - - recovery_eof = rec.key_len; - - data = (unsigned char *)malloc(rec.data_len); - if (data == NULL) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n")); - tdb->ecode = TDB_ERR_OOM; - return -1; - } - - /* read the full recovery data */ - if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data, - rec.data_len, 0) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - - /* recover the file data */ - p = data; - while (p+8 < data + rec.data_len) { - uint32_t ofs, len; - if (DOCONV()) { - tdb_convert(p, 8); - } - memcpy(&ofs, p, 4); - memcpy(&len, p+4, 4); - - if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) { - free(data); - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs)); - tdb->ecode = TDB_ERR_IO; - return -1; - } - p += 8 + len; - } - - free(data); - - if (transaction_sync(tdb, 0, tdb->map_size) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - - /* if the recovery area is after the recovered eof then remove it */ - if (recovery_eof <= recovery_head) { - if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - } - - /* remove the recovery magic */ - if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic), - &zero) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - - /* reduce the file size to the old size */ - tdb_munmap(tdb); - if (ftruncate(tdb->fd, recovery_eof) != 0) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - tdb->map_size = recovery_eof; - tdb_mmap(tdb); - - if (transaction_sync(tdb, 0, recovery_eof) == -1) { - TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n")); - tdb->ecode = TDB_ERR_IO; - return -1; - } - - TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n", - recovery_eof)); - - /* all done */ - return 0; -} |