X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb2%2Ftransaction.c;h=2afc1789b0e1fa370d8f28453b33e734d6c035b3;hp=68ae234d2f90ccbe4fb993dd27476df7c89afba2;hb=fbad02b680b6cbc33ae305ae1cbcdead4eedc7b1;hpb=8cca0397ef6f6017b13ce9ab4999bf3d92a2dee5

diff --git a/ccan/tdb2/transaction.c b/ccan/tdb2/transaction.c
index 68ae234d..2afc1789 100644
--- a/ccan/tdb2/transaction.c
+++ b/ccan/tdb2/transaction.c
@@ -88,7 +88,6 @@
     fsync/msync calls are made.
 */
 
-
 /*
   hold the context of any current transaction
 */
@@ -110,7 +109,7 @@ struct tdb_transaction {
 	/* 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;
+	unsigned int nesting;
 
 	/* set when a prepare has already occurred */
 	bool prepared;
@@ -121,7 +120,7 @@ struct tdb_transaction {
 };
 
 /* This doesn't really need to be pagesize, but we use it for similar reasons. */
-#define PAGESIZE 4096
+#define PAGESIZE 65536
 
 /*
   read while in a transaction. We need to check first if the data is in our list
@@ -349,15 +348,14 @@ static void transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
 static enum TDB_ERROR transaction_oob(struct tdb_context *tdb, tdb_off_t len,
 				      bool probe)
 {
-	if (len <= tdb->file->map_size) {
+	if (len <= tdb->file->map_size || probe) {
 		return TDB_SUCCESS;
 	}
-	if (!probe) {
-		tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
-			   "tdb_oob len %lld beyond transaction size %lld",
-			   (long long)len,
-			   (long long)tdb->file->map_size);
-	}
+
+	tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+		   "tdb_oob len %lld beyond transaction size %lld",
+		   (long long)len,
+		   (long long)tdb->file->map_size);
 	return TDB_ERR_IO;
 }
 
@@ -388,15 +386,17 @@ static void *transaction_direct(struct tdb_context *tdb, tdb_off_t off,
 
 	/* Can only do direct if in single block and we've already copied. */
 	if (write_mode) {
-		if (blk != end_blk)
-			return NULL;
-		if (blk >= tdb->transaction->num_blocks)
-			return NULL;
-		if (tdb->transaction->blocks[blk] == NULL)
+		tdb->stats.transaction_write_direct++;
+		if (blk != end_blk
+		    || blk >= tdb->transaction->num_blocks
+		    || tdb->transaction->blocks[blk] == NULL) {
+			tdb->stats.transaction_write_direct_fail++;
 			return NULL;
+		}
 		return tdb->transaction->blocks[blk] + off % PAGESIZE;
 	}
 
+	tdb->stats.transaction_read_direct++;
 	/* Single which we have copied? */
 	if (blk == end_blk
 	    && blk < tdb->transaction->num_blocks
@@ -407,8 +407,10 @@ static void *transaction_direct(struct tdb_context *tdb, tdb_off_t off,
 	while (blk <= end_blk) {
 		if (blk >= tdb->transaction->num_blocks)
 			break;
-		if (tdb->transaction->blocks[blk])
+		if (tdb->transaction->blocks[blk]) {
+			tdb->stats.transaction_read_direct_fail++;
 			return NULL;
+		}
 		blk++;
 	}
 	return tdb->transaction->io_methods->direct(tdb, off, len, false);
@@ -439,7 +441,7 @@ static enum TDB_ERROR transaction_sync(struct tdb_context *tdb,
 	}
 #ifdef MS_SYNC
 	if (tdb->file->map_ptr) {
-		tdb_off_t moffset = offset & ~(PAGESIZE-1);
+		tdb_off_t moffset = offset & ~(getpagesize()-1);
 		if (msync(moffset + (char *)tdb->file->map_ptr,
 			  length + (offset - moffset), MS_SYNC) != 0) {
 			return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
@@ -506,7 +508,7 @@ static void _tdb_transaction_cancel(struct tdb_context *tdb)
 	tdb_transaction_unlock(tdb, F_WRLCK);
 
 	if (tdb_has_open_lock(tdb))
-		tdb_unlock_open(tdb);
+		tdb_unlock_open(tdb, F_WRLCK);
 
 	SAFE_FREE(tdb->transaction);
 }
@@ -519,23 +521,38 @@ enum TDB_ERROR tdb_transaction_start(struct tdb_context *tdb)
 {
 	enum TDB_ERROR ecode;
 
+	tdb->stats.transactions++;
 	/* some sanity checks */
-	if (tdb->read_only || (tdb->flags & TDB_INTERNAL)) {
+	if (tdb->flags & TDB_INTERNAL) {
 		return tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
+						    TDB_LOG_USE_ERROR,
+						    "tdb_transaction_start:"
+						    " cannot start a"
+						    " transaction on an"
+						    " internal tdb");
+	}
+
+	if (tdb->flags & TDB_RDONLY) {
+		return tdb->last_error = tdb_logerr(tdb, TDB_ERR_RDONLY,
 						    TDB_LOG_USE_ERROR,
 						    "tdb_transaction_start:"
 						    " cannot start a"
 						    " transaction on a "
-						    "read-only or internal db");
+						    " read-only tdb");
 	}
 
 	/* cope with nested tdb_transaction_start() calls */
 	if (tdb->transaction != NULL) {
-		return tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO,
-						    TDB_LOG_USE_ERROR,
-						    "tdb_transaction_start:"
-						    " already inside"
-						    " transaction");
+		if (!(tdb->flags & TDB_ALLOW_NESTING)) {
+			return tdb->last_error
+				= tdb_logerr(tdb, TDB_ERR_IO,
+					     TDB_LOG_USE_ERROR,
+					     "tdb_transaction_start:"
+					     " already inside transaction");
+		}
+		tdb->transaction->nesting++;
+		tdb->stats.transaction_nest++;
+		return 0;
 	}
 
 	if (tdb_has_hash_locks(tdb)) {
@@ -600,18 +617,19 @@ fail_allrecord_lock:
 */
 void tdb_transaction_cancel(struct tdb_context *tdb)
 {
+	tdb->stats.transaction_cancel++;
 	_tdb_transaction_cancel(tdb);
 }
 
 /*
-  work out how much space the linearised recovery data will consume
+  work out how much space the linearised recovery data will consume (worst case)
 */
 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
 {
 	tdb_len_t recovery_size = 0;
 	int i;
 
-	recovery_size = sizeof(tdb_len_t);
+	recovery_size = 0;
 	for (i=0;i<tdb->transaction->num_blocks;i++) {
 		if (i * PAGESIZE >= tdb->transaction->old_map_size) {
 			break;
@@ -630,87 +648,198 @@ static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
 	return recovery_size;
 }
 
-/*
-  allocate the recovery area, or use an existing recovery area if it is
-  large enough
-*/
-static enum TDB_ERROR tdb_recovery_allocate(struct tdb_context *tdb,
-					    tdb_len_t *recovery_size,
-					    tdb_off_t *recovery_offset,
-					    tdb_len_t *recovery_max_size)
+static enum TDB_ERROR tdb_recovery_area(struct tdb_context *tdb,
+					const struct tdb_methods *methods,
+					tdb_off_t *recovery_offset,
+					struct tdb_recovery_record *rec)
 {
-	struct tdb_recovery_record rec;
-	const struct tdb_methods *methods = tdb->transaction->io_methods;
-	tdb_off_t recovery_head;
-	size_t addition;
 	enum TDB_ERROR ecode;
 
-	recovery_head = tdb_read_off(tdb, offsetof(struct tdb_header,recovery));
-	if (TDB_OFF_IS_ERR(recovery_head)) {
-		return tdb_logerr(tdb, recovery_head, TDB_LOG_ERROR,
-				  "tdb_recovery_allocate:"
-				  " failed to read recovery head");
+	*recovery_offset = tdb_read_off(tdb,
+					offsetof(struct tdb_header, recovery));
+	if (TDB_OFF_IS_ERR(*recovery_offset)) {
+		return *recovery_offset;
 	}
 
-	if (recovery_head != 0) {
-		ecode = methods->tread(tdb, recovery_head, &rec, sizeof(rec));
-		if (ecode != TDB_SUCCESS) {
-			return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
-					  "tdb_recovery_allocate:"
-					  " failed to read recovery record");
-		}
-		tdb_convert(tdb, &rec, sizeof(rec));
-		/* ignore invalid recovery regions: can happen in crash */
-		if (rec.magic != TDB_RECOVERY_MAGIC &&
-		    rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
-			recovery_head = 0;
+	if (*recovery_offset == 0) {
+		rec->max_len = 0;
+		return TDB_SUCCESS;
+	}
+
+	ecode = methods->tread(tdb, *recovery_offset, rec, sizeof(*rec));
+	if (ecode != TDB_SUCCESS)
+		return ecode;
+
+	tdb_convert(tdb, rec, sizeof(*rec));
+	/* ignore invalid recovery regions: can happen in crash */
+	if (rec->magic != TDB_RECOVERY_MAGIC &&
+	    rec->magic != TDB_RECOVERY_INVALID_MAGIC) {
+		*recovery_offset = 0;
+		rec->max_len = 0;
+	}
+	return TDB_SUCCESS;
+}
+
+static unsigned int same(const unsigned char *new,
+			 const unsigned char *old,
+			 unsigned int length)
+{
+	unsigned int i;
+
+	for (i = 0; i < length; i++) {
+		if (new[i] != old[i])
+			break;
+	}
+	return i;
+}
+
+static unsigned int different(const unsigned char *new,
+			      const unsigned char *old,
+			      unsigned int length,
+			      unsigned int min_same,
+			      unsigned int *samelen)
+{
+	unsigned int i;
+
+	*samelen = 0;
+	for (i = 0; i < length; i++) {
+		if (new[i] == old[i]) {
+			(*samelen)++;
+		} else {
+			if (*samelen >= min_same) {
+				return i - *samelen;
+			}
+			*samelen = 0;
 		}
 	}
 
-	*recovery_size = tdb_recovery_size(tdb);
+	if (*samelen < min_same)
+		*samelen = 0;
+	return length - *samelen;
+}
 
-	if (recovery_head != 0 && *recovery_size <= rec.max_len) {
-		/* it fits in the existing area */
-		*recovery_max_size = rec.max_len;
-		*recovery_offset = recovery_head;
-		return TDB_SUCCESS;
+/* Allocates recovery blob, without tdb_recovery_record at head set up. */
+static struct tdb_recovery_record *alloc_recovery(struct tdb_context *tdb,
+						  tdb_len_t *len)
+{
+	struct tdb_recovery_record *rec;
+	size_t i;
+	enum TDB_ERROR ecode;
+	unsigned char *p;
+	const struct tdb_methods *old_methods = tdb->methods;
+
+	rec = malloc(sizeof(*rec) + tdb_recovery_size(tdb));
+	if (!rec) {
+		tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
+			   "transaction_setup_recovery:"
+			   " cannot allocate");
+		return TDB_ERR_PTR(TDB_ERR_OOM);
 	}
 
-	/* 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
-	   normal allocation 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) {
-		tdb->stats.frees++;
-		ecode = add_free_record(tdb, recovery_head,
-					sizeof(rec) + rec.max_len);
-		if (ecode != TDB_SUCCESS) {
-			return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
-					  "tdb_recovery_allocate:"
-					  " failed to free previous"
-					  " recovery area");
+	/* We temporarily revert to the old I/O methods, so we can use
+	 * tdb_access_read */
+	tdb->methods = tdb->transaction->io_methods;
+
+	/* build the recovery data into a single blob to allow us to do a single
+	   large write, which should be more efficient */
+	p = (unsigned char *)(rec + 1);
+	for (i=0;i<tdb->transaction->num_blocks;i++) {
+		tdb_off_t offset;
+		tdb_len_t length;
+		unsigned int off;
+		const unsigned char *buffer;
+
+		if (tdb->transaction->blocks[i] == NULL) {
+			continue;
 		}
+
+		offset = i * PAGESIZE;
+		length = PAGESIZE;
+		if (i == tdb->transaction->num_blocks-1) {
+			length = tdb->transaction->last_block_size;
+		}
+
+		if (offset >= tdb->transaction->old_map_size) {
+			continue;
+		}
+
+		if (offset + length > tdb->file->map_size) {
+			ecode = tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
+					   "tdb_transaction_setup_recovery:"
+					   " transaction data over new region"
+					   " boundary");
+			goto fail;
+		}
+		if (offset + length > tdb->transaction->old_map_size) {
+			/* Short read at EOF. */
+			length = tdb->transaction->old_map_size - offset;
+		}
+		buffer = tdb_access_read(tdb, offset, length, false);
+		if (TDB_PTR_IS_ERR(buffer)) {
+			ecode = TDB_PTR_ERR(buffer);
+			goto fail;
+		}
+
+		/* Skip over anything the same at the start. */
+		off = same(tdb->transaction->blocks[i], buffer, length);
+		offset += off;
+
+		while (off < length) {
+			tdb_len_t len;
+			unsigned int samelen;
+
+			len = different(tdb->transaction->blocks[i] + off,
+					buffer + off, length - off,
+					sizeof(offset) + sizeof(len) + 1,
+					&samelen);
+
+			memcpy(p, &offset, sizeof(offset));
+			memcpy(p + sizeof(offset), &len, sizeof(len));
+			tdb_convert(tdb, p, sizeof(offset) + sizeof(len));
+			p += sizeof(offset) + sizeof(len);
+			memcpy(p, buffer + off, len);
+			p += len;
+			off += len + samelen;
+			offset += len + samelen;
+		}
+		tdb_access_release(tdb, buffer);
 	}
 
-	/* the tdb_free() call might have increased the recovery size */
-	*recovery_size = tdb_recovery_size(tdb);
+	*len = p - (unsigned char *)(rec + 1);
+	tdb->methods = old_methods;
+	return rec;
 
-	/* round up to a multiple of page size */
-	*recovery_max_size
-		= (((sizeof(rec) + *recovery_size) + PAGESIZE-1)
-		   & ~(PAGESIZE-1))
-		- sizeof(rec);
-	*recovery_offset = tdb->file->map_size;
-	recovery_head = *recovery_offset;
+fail:
+	free(rec);
+	tdb->methods = old_methods;
+	return TDB_ERR_PTR(ecode);
+}
+
+static tdb_off_t create_recovery_area(struct tdb_context *tdb,
+				      tdb_len_t rec_length,
+				      struct tdb_recovery_record *rec)
+{
+	tdb_off_t off, recovery_off;
+	tdb_len_t addition;
+	enum TDB_ERROR ecode;
+	const struct tdb_methods *methods = tdb->transaction->io_methods;
+
+	/* round up to a multiple of page size. Overallocate, since each
+	 * such allocation forces us to expand the file. */
+	rec->max_len
+		= (((sizeof(*rec) + rec_length + rec_length / 2)
+		    + PAGESIZE-1) & ~(PAGESIZE-1))
+		- sizeof(*rec);
+	off = tdb->file->map_size;
 
 	/* Restore ->map_size before calling underlying expand_file.
 	   Also so that we don't try to expand the file again in the
 	   transaction commit, which would destroy the recovery
 	   area */
 	addition = (tdb->file->map_size - tdb->transaction->old_map_size) +
-		sizeof(rec) + *recovery_max_size;
+		sizeof(*rec) + rec->max_len;
 	tdb->file->map_size = tdb->transaction->old_map_size;
+	tdb->stats.transaction_expand_file++;
 	ecode = methods->expand_file(tdb, addition);
 	if (ecode != TDB_SUCCESS) {
 		return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
@@ -725,159 +854,118 @@ static enum TDB_ERROR tdb_recovery_allocate(struct tdb_context *tdb,
 
 	/* 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 */
-	tdb_convert(tdb, &recovery_head, sizeof(recovery_head));
+	recovery_off = off;
+	tdb_convert(tdb, &recovery_off, sizeof(recovery_off));
 	ecode = methods->twrite(tdb, offsetof(struct tdb_header, recovery),
-				&recovery_head, sizeof(tdb_off_t));
+				&recovery_off, sizeof(tdb_off_t));
 	if (ecode != TDB_SUCCESS) {
 		return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
 				  "tdb_recovery_allocate:"
 				  " failed to write recovery head");
 	}
 	transaction_write_existing(tdb, offsetof(struct tdb_header, recovery),
-				   &recovery_head,
+				   &recovery_off,
 				   sizeof(tdb_off_t));
-	return TDB_SUCCESS;
-}
-
-/* Set up header for the recovery record. */
-static void set_recovery_header(struct tdb_recovery_record *rec,
-				uint64_t magic,
-				uint64_t datalen, uint64_t actuallen,
-				uint64_t oldsize)
-{
-	rec->magic = magic;
-	rec->max_len = actuallen;
-	rec->len = datalen;
-	rec->eof = oldsize;
+	return off;
 }
 
 /*
   setup the recovery data that will be used on a crash during commit
 */
-static enum TDB_ERROR transaction_setup_recovery(struct tdb_context *tdb,
-						 tdb_off_t *magic_offset)
+static enum TDB_ERROR transaction_setup_recovery(struct tdb_context *tdb)
 {
-	/* Initialized for GCC's 4.4.5 overzealous uninitialized warnings. */
 	tdb_len_t recovery_size = 0;
-	tdb_off_t recovery_offset = 0, recovery_max_size = 0;
-	unsigned char *data, *p;
-	const struct tdb_methods *methods = tdb->transaction->io_methods;
-	struct tdb_recovery_record *rec;
+	tdb_off_t recovery_off = 0;
 	tdb_off_t old_map_size = tdb->transaction->old_map_size;
-	uint64_t magic, tailer;
-	int i;
+	struct tdb_recovery_record *recovery;
+	const struct tdb_methods *methods = tdb->transaction->io_methods;
+	uint64_t magic;
 	enum TDB_ERROR ecode;
 
-	/*
-	  check that the recovery area has enough space
-	*/
-	ecode = tdb_recovery_allocate(tdb, &recovery_size,
-				      &recovery_offset, &recovery_max_size);
-	if (ecode != TDB_SUCCESS) {
-		return ecode;
-	}
+	recovery = alloc_recovery(tdb, &recovery_size);
+	if (TDB_PTR_IS_ERR(recovery))
+		return TDB_PTR_ERR(recovery);
 
-	data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
-	if (data == NULL) {
-		return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
-				  "transaction_setup_recovery:"
-				  " cannot allocate");
+	ecode = tdb_recovery_area(tdb, methods, &recovery_off, recovery);
+	if (ecode) {
+		free(recovery);
+		return ecode;
 	}
 
-	rec = (struct tdb_recovery_record *)data;
-	set_recovery_header(rec, TDB_RECOVERY_INVALID_MAGIC,
-			    recovery_size, recovery_max_size, old_map_size);
-	tdb_convert(tdb, rec, sizeof(*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 (recovery->max_len < recovery_size) {
+		/* Not large enough. Free up old recovery area. */
+		if (recovery_off) {
+			tdb->stats.frees++;
+			ecode = add_free_record(tdb, recovery_off,
+						sizeof(*recovery)
+						+ recovery->max_len,
+						TDB_LOCK_WAIT, true);
+			free(recovery);
+			if (ecode != TDB_SUCCESS) {
+				return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
+						  "tdb_recovery_allocate:"
+						  " failed to free previous"
+						  " recovery area");
+			}
 
-		if (tdb->transaction->blocks[i] == NULL) {
-			continue;
+			/* Refresh recovery after add_free_record above. */
+			recovery = alloc_recovery(tdb, &recovery_size);
+			if (TDB_PTR_IS_ERR(recovery))
+				return TDB_PTR_ERR(recovery);
 		}
 
-		offset = i * PAGESIZE;
-		length = PAGESIZE;
-		if (i == tdb->transaction->num_blocks-1) {
-			length = tdb->transaction->last_block_size;
+		recovery_off = create_recovery_area(tdb, recovery_size,
+						    recovery);
+		if (TDB_OFF_IS_ERR(recovery_off)) {
+			free(recovery);
+			return recovery_off;
 		}
-
-		if (offset >= old_map_size) {
-			continue;
-		}
-		if (offset + length > tdb->file->map_size) {
-			free(data);
-			return tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
-					  "tdb_transaction_setup_recovery:"
-					  " transaction data over new region"
-					  " boundary");
-		}
-		memcpy(p, &offset, sizeof(offset));
-		memcpy(p + sizeof(offset), &length, sizeof(length));
-		tdb_convert(tdb, p, sizeof(offset) + sizeof(length));
-
-		/* the recovery area contains the old data, not the
-		   new data, so we have to call the original tdb_read
-		   method to get it */
-		ecode = methods->tread(tdb, offset,
-				       p + sizeof(offset) + sizeof(length),
-				       length);
-		if (ecode != TDB_SUCCESS) {
-			free(data);
-			return ecode;
-		}
-		p += sizeof(offset) + sizeof(length) + length;
 	}
 
-	/* and the tailer */
-	tailer = sizeof(*rec) + recovery_max_size;
-	memcpy(p, &tailer, sizeof(tailer));
-	tdb_convert(tdb, p, sizeof(tailer));
+	/* Now we know size, convert rec header. */
+	recovery->magic = TDB_RECOVERY_INVALID_MAGIC;
+	recovery->len = recovery_size;
+	recovery->eof = old_map_size;
+	tdb_convert(tdb, recovery, sizeof(*recovery));
 
 	/* write the recovery data to the recovery area */
-	ecode = methods->twrite(tdb, recovery_offset, data,
-				sizeof(*rec) + recovery_size);
+	ecode = methods->twrite(tdb, recovery_off, recovery, recovery_size);
 	if (ecode != TDB_SUCCESS) {
-		free(data);
+		free(recovery);
 		return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
 				  "tdb_transaction_setup_recovery:"
 				  " failed to write recovery data");
 	}
-	transaction_write_existing(tdb, recovery_offset, data,
-				   sizeof(*rec) + recovery_size);
+	transaction_write_existing(tdb, recovery_off, recovery, recovery_size);
+
+	free(recovery);
 
 	/* 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 */
-	ecode = transaction_sync(tdb, recovery_offset,
-				 sizeof(*rec) + recovery_size);
-	if (ecode != TDB_SUCCESS) {
-		free(data);
+	ecode = transaction_sync(tdb, recovery_off, recovery_size);
+	if (ecode != TDB_SUCCESS)
 		return ecode;
-	}
-
-	free(data);
 
 	magic = TDB_RECOVERY_MAGIC;
 	tdb_convert(tdb, &magic, sizeof(magic));
 
-	*magic_offset = recovery_offset + offsetof(struct tdb_recovery_record,
-						   magic);
+	tdb->transaction->magic_offset
+		= recovery_off + offsetof(struct tdb_recovery_record, magic);
 
-	ecode = methods->twrite(tdb, *magic_offset, &magic, sizeof(magic));
+	ecode = methods->twrite(tdb, tdb->transaction->magic_offset,
+				&magic, sizeof(magic));
 	if (ecode != TDB_SUCCESS) {
 		return tdb_logerr(tdb, ecode, TDB_LOG_ERROR,
 				  "tdb_transaction_setup_recovery:"
 				  " failed to write recovery magic");
 	}
-	transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic));
+	transaction_write_existing(tdb, tdb->transaction->magic_offset,
+				   &magic, sizeof(magic));
 
 	/* ensure the recovery magic marker is on disk */
-	return transaction_sync(tdb, *magic_offset, sizeof(magic));
+	return transaction_sync(tdb, tdb->transaction->magic_offset,
+				sizeof(magic));
 }
 
 static enum TDB_ERROR _tdb_transaction_prepare_commit(struct tdb_context *tdb)
@@ -907,7 +995,6 @@ static enum TDB_ERROR _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 
 
 	if (tdb->transaction->nesting != 0) {
-		tdb->transaction->nesting--;
 		return TDB_SUCCESS;
 	}
 
@@ -919,24 +1006,23 @@ static enum TDB_ERROR _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 	methods = tdb->transaction->io_methods;
 
 	/* upgrade the main transaction lock region to a write lock */
-	ecode = tdb_allrecord_upgrade(tdb);
+	ecode = tdb_allrecord_upgrade(tdb, TDB_HASH_LOCK_START);
 	if (ecode != TDB_SUCCESS) {
 		return ecode;
 	}
 
 	/* get the open lock - this prevents new users attaching to the database
 	   during the commit */
-	ecode = tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK);
+	ecode = tdb_lock_open(tdb, F_WRLCK, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK);
 	if (ecode != TDB_SUCCESS) {
 		return ecode;
 	}
 
 	/* Since we have whole db locked, we don't need the expansion lock. */
 	if (!(tdb->flags & TDB_NOSYNC)) {
-		/* write the recovery data to the end of the file */
-		ecode = transaction_setup_recovery(tdb,
-						   &tdb->transaction
-						   ->magic_offset);
+		/* Sets up tdb->transaction->recovery and
+		 * tdb->transaction->magic_offset. */
+		ecode = transaction_setup_recovery(tdb);
 		if (ecode != TDB_SUCCESS) {
 			return ecode;
 		}
@@ -1110,7 +1196,7 @@ enum TDB_ERROR tdb_transaction_recover(struct tdb_context *tdb)
 		return TDB_SUCCESS;
 	}
 
-	if (tdb->read_only) {
+	if (tdb->flags & TDB_RDONLY) {
 		return tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
 				  "tdb_transaction_recover:"
 				  " attempt to recover read only database");