tdb: use tdb_nest_lock() for open lock.

This never nests, so it's overkill, but it centralizes the locking into
lock.c and removes the ugly flag in the transaction code to track whether
we have the lock or not.

Note that we have a temporary hack so this places a real lock, despite
the fact that we are in a transaction.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 5 insertions, 12 deletions

diff --git a/lib/tdb/common/transaction.c b/lib/tdb/common/transaction.c
index 02ef72a357..69a622dae0 100644
--- a/lib/tdb/common/transaction.c
+++ b/lib/tdb/common/transaction.c
@@ -135,9 +135,6 @@ struct tdb_transaction {
 	bool prepared;
 	tdb_off_t magic_offset;
 
-	/* set when the OPEN_LOCK has been taken */
-	bool open_lock_taken;
-
 	/* old file size before transaction */
 	tdb_len_t old_map_size;
 
@@ -418,6 +415,9 @@ static int transaction_brlock(struct tdb_context *tdb,
 			      int rw_type, tdb_off_t offset, size_t len,
 			      enum tdb_lock_flags flags)
 {
+	/* FIXME: We actually grab the open lock during a transaction. */
+	if (offset == OPEN_LOCK)
+		return tdb_brlock(tdb, rw_type, offset, len, flags);
 	return 0;
 }
 
@@ -615,11 +615,7 @@ static int _tdb_transaction_cancel(struct tdb_context *tdb, int ltype)
 		}
 	}
 
-	if (tdb->transaction->open_lock_taken) {
-		tdb_brunlock(tdb, F_WRLCK, OPEN_LOCK, 1);
-		tdb->transaction->open_lock_taken = false;
-	}
-
+	/* This also removes the OPEN_LOCK, if we have it. */
 	tdb_release_extra_locks(tdb);
 
 	/* restore the normal io methods */
@@ -951,15 +947,12 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 
 	/* get the open lock - this prevents new users attaching to the database
 	   during the commit */
-	if (tdb_brlock(tdb, F_WRLCK, OPEN_LOCK, 1, TDB_LOCK_WAIT) == -1) {
+	if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
 		TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
-		tdb->ecode = TDB_ERR_LOCK;
 		_tdb_transaction_cancel(tdb, F_WRLCK);
 		return -1;
 	}
 
-	tdb->transaction->open_lock_taken = true;
-
 	if (!(tdb->flags & TDB_NOSYNC)) {
 		/* write the recovery data to the end of the file */
 		if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {