X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Ftdb%2Ftransaction.c;h=e55285f94cc6609a2afa720d39fe66d2261a36fe;hp=0944bb36e98a6a3af4e32ac2052e512483bc4311;hb=1bc7c4367132a36c05ac1b3afcbec70a6e26540d;hpb=059678ec4216112f96d8ad992ec7c0b8a6e3b80b

diff --git a/ccan/tdb/transaction.c b/ccan/tdb/transaction.c
index 0944bb36..e55285f9 100644
--- a/ccan/tdb/transaction.c
+++ b/ccan/tdb/transaction.c
@@ -85,11 +85,13 @@
     still available, but no transaction recovery area is used and no
     fsync/msync calls are made.
 
-  - if TDB_NO_NESTING is passed to flags in tdb open then transaction
-    nesting is disabled. tdb_transaction_start() will then implicitely
-    cancel any pending transactions and always start a new transaction
-    context instead of nesting.
+  - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
+    tdb_add_flags() transaction is enabled.
+    The default is that transaction nesting is not allowed and an attempt
+    to create a nested transaction will fail with TDB_ERR_NESTING.
 
+    Beware. when transactions are nested a transaction successfully
+    completed with tdb_transaction_commit() can be silently unrolled later.
 */
 
 
@@ -385,7 +387,8 @@ 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);
+	tdb->ecode = TDB_ERR_IO;
+	return -1;
 }
 
 /*
@@ -532,16 +535,15 @@ int tdb_transaction_start(struct tdb_context *tdb)
 
 	/* cope with nested tdb_transaction_start() calls */
 	if (tdb->transaction != NULL) {
-		tdb_trace(tdb, "tdb_transaction_start");
-		if (!tdb->flags & TDB_NO_NESTING) {
-			tdb->transaction->nesting++;
-			TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n", 
-				 tdb->transaction->nesting));
-			return 0;
-		} else {
-			tdb_transaction_cancel_internal(tdb);
-			TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: cancelling previous transaction\n"));
+		if (!(tdb->flags & TDB_ALLOW_NESTING)) {
+			tdb->ecode = TDB_ERR_NESTING;
+			return -1;
 		}
+		tdb_trace(tdb, "tdb_transaction_start");
+		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) {