diff --git a/source3/include/g_lock.h b/source3/include/g_lock.h
index c96431346a6..d6c1521a52c 100644
--- a/source3/include/g_lock.h
+++ b/source3/include/g_lock.h
@@ -79,7 +79,9 @@ struct tevent_req *g_lock_lock_send(TALLOC_CTX *mem_ctx,
 				    void *cb_private);
 NTSTATUS g_lock_lock_recv(struct tevent_req *req);
 NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, TDB_DATA key,
-		     enum g_lock_type lock_type, struct timeval timeout);
+		     enum g_lock_type lock_type, struct timeval timeout,
+		     g_lock_lock_cb_fn_t cb_fn,
+		     void *cb_private);
 NTSTATUS g_lock_unlock(struct g_lock_ctx *ctx, TDB_DATA key);
 
 NTSTATUS g_lock_writev_data(
diff --git a/source3/lib/dbwrap/dbwrap_ctdb.c b/source3/lib/dbwrap/dbwrap_ctdb.c
index 1f0907c91a8..46165e8fbfb 100644
--- a/source3/lib/dbwrap/dbwrap_ctdb.c
+++ b/source3/lib/dbwrap/dbwrap_ctdb.c
@@ -382,7 +382,7 @@ static int db_ctdb_transaction_start(struct db_context *db)
 	 * Wait a day, i.e. forever...
 	 */
 	status = g_lock_lock(ctx->lock_ctx, string_term_tdb_data(h->lock_name),
-			     G_LOCK_WRITE, timeval_set(86400, 0));
+			     G_LOCK_WRITE, timeval_set(86400, 0), NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		DEBUG(0, ("g_lock_lock failed: %s\n", nt_errstr(status)));
 		TALLOC_FREE(h);
diff --git a/source3/lib/g_lock.c b/source3/lib/g_lock.c
index a22f9dcad06..40687f47526 100644
--- a/source3/lib/g_lock.c
+++ b/source3/lib/g_lock.c
@@ -1225,10 +1225,10 @@ not_granted:
 }
 
 NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, TDB_DATA key,
-		     enum g_lock_type type, struct timeval timeout)
+		     enum g_lock_type type, struct timeval timeout,
+		     g_lock_lock_cb_fn_t cb_fn,
+		     void *cb_private)
 {
-	g_lock_lock_cb_fn_t cb_fn = NULL;
-	void *cb_private = NULL;
 	TALLOC_CTX *frame;
 	struct tevent_context *ev;
 	struct tevent_req *req;
@@ -1237,6 +1237,16 @@ NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, TDB_DATA key,
 
 	SMB_ASSERT(!ctx->busy);
 
+	/*
+	 * We allow a cn_fn only for G_LOCK_WRITE for now.
+	 *
+	 * It's all we currently need and it makes a few things
+	 * easier to implement.
+	 */
+	if (unlikely(cb_fn != NULL && type != G_LOCK_WRITE)) {
+		return NT_STATUS_INVALID_PARAMETER_5;
+	}
+
 	if ((type == G_LOCK_READ) || (type == G_LOCK_WRITE)) {
 		/*
 		 * This is an abstraction violation: Normally we do
diff --git a/source3/libsmb/trusts_util.c b/source3/libsmb/trusts_util.c
index 356366b6a9d..c86bceac7d6 100644
--- a/source3/libsmb/trusts_util.c
+++ b/source3/libsmb/trusts_util.c
@@ -201,7 +201,7 @@ NTSTATUS trust_pw_change(struct netlogon_creds_cli_context *context,
 	g_timeout = timeval_current_ofs(10, 0);
 	status = g_lock_lock(state->g_ctx,
 			     string_term_tdb_data(state->g_lock_key),
-			     G_LOCK_WRITE, g_timeout);
+			     G_LOCK_WRITE, g_timeout, NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		DEBUG(1, ("could not get g_lock on [%s]!\n",
 			  state->g_lock_key));
diff --git a/source3/locking/share_mode_lock.c b/source3/locking/share_mode_lock.c
index 347223c5853..4575792942c 100644
--- a/source3/locking/share_mode_lock.c
+++ b/source3/locking/share_mode_lock.c
@@ -887,7 +887,8 @@ static NTSTATUS get_share_mode_lock_internal(
 			lock_ctx,
 			key,
 			G_LOCK_WRITE,
-			(struct timeval) { .tv_sec = 3600 });
+			(struct timeval) { .tv_sec = 3600 },
+			NULL, NULL);
 		if (!NT_STATUS_IS_OK(status)) {
 			DBG_DEBUG("g_lock_lock failed: %s\n",
 				  nt_errstr(status));
diff --git a/source3/smbd/server.c b/source3/smbd/server.c
index 25cb84ab9d0..9b211238c11 100644
--- a/source3/smbd/server.c
+++ b/source3/smbd/server.c
@@ -1471,8 +1471,12 @@ static NTSTATUS smbd_claim_version(struct messaging_context *msg,
 		return NT_STATUS_UNSUCCESSFUL;
 	}
 
-	status = g_lock_lock(
-		ctx, key, G_LOCK_READ, (struct timeval) { .tv_sec = 60 });
+	status = g_lock_lock(ctx,
+			     key,
+			     G_LOCK_READ,
+			     (struct timeval) { .tv_sec = 60 },
+			     NULL,
+			     NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		DBG_WARNING("g_lock_lock(G_LOCK_READ) failed: %s\n",
 			    nt_errstr(status));
@@ -1500,8 +1504,12 @@ static NTSTATUS smbd_claim_version(struct messaging_context *msg,
 		return NT_STATUS_OK;
 	}
 
-	status = g_lock_lock(
-		ctx, key, G_LOCK_UPGRADE, (struct timeval) { .tv_sec = 60 });
+	status = g_lock_lock(ctx,
+			     key,
+			     G_LOCK_UPGRADE,
+			     (struct timeval) { .tv_sec = 60 },
+			     NULL,
+			     NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		DBG_WARNING("g_lock_lock(G_LOCK_WRITE) failed: %s\n",
 			    nt_errstr(status));
@@ -1520,8 +1528,12 @@ static NTSTATUS smbd_claim_version(struct messaging_context *msg,
 		return status;
 	}
 
-	status = g_lock_lock(
-		ctx, key, G_LOCK_DOWNGRADE, (struct timeval) { .tv_sec = 60 });
+	status = g_lock_lock(ctx,
+			     key,
+			     G_LOCK_DOWNGRADE,
+			     (struct timeval) { .tv_sec = 60 },
+			     NULL,
+			     NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		DBG_WARNING("g_lock_lock(G_LOCK_READ) failed: %s\n",
 			    nt_errstr(status));
diff --git a/source3/torture/test_g_lock.c b/source3/torture/test_g_lock.c
index 57899e9e337..ad3793633f3 100644
--- a/source3/torture/test_g_lock.c
+++ b/source3/torture/test_g_lock.c
@@ -71,7 +71,8 @@ bool run_g_lock1(int dummy)
 	}
 
 	status = g_lock_lock(ctx, string_term_tdb_data(lockname), G_LOCK_WRITE,
-			     (struct timeval) { .tv_sec = 1 });
+			     (struct timeval) { .tv_sec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr, "g_lock_lock failed: %s\n",
 			nt_errstr(status));
@@ -79,7 +80,8 @@ bool run_g_lock1(int dummy)
 	}
 
 	status = g_lock_lock(ctx, string_term_tdb_data(lockname), G_LOCK_WRITE,
-			     (struct timeval) { .tv_sec = 1 });
+			     (struct timeval) { .tv_sec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_EQUAL(status, NT_STATUS_WAS_LOCKED)) {
 		fprintf(stderr, "Double lock got %s\n",
 			nt_errstr(status));
@@ -160,7 +162,8 @@ bool run_g_lock2(int dummy)
 	}
 
 	status = g_lock_lock(ctx, string_term_tdb_data(lockname), G_LOCK_WRITE,
-			     (struct timeval) { .tv_sec = 1 });
+			     (struct timeval) { .tv_sec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr, "g_lock_lock returned %s\n",
 			nt_errstr(status));
@@ -282,7 +285,8 @@ bool run_g_lock3(int dummy)
 	state.self = messaging_server_id(msg);
 
 	status = g_lock_lock(ctx, string_term_tdb_data(lockname), G_LOCK_READ,
-			     (struct timeval) { .tv_sec = 1 });
+			     (struct timeval) { .tv_sec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr, "g_lock_lock returned %s\n",
 			nt_errstr(status));
@@ -304,7 +308,8 @@ bool run_g_lock3(int dummy)
 	}
 
 	status = g_lock_lock(ctx, string_term_tdb_data(lockname), G_LOCK_UPGRADE,
-			     (struct timeval) { .tv_sec = 1 });
+			     (struct timeval) { .tv_sec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr, "g_lock_lock returned %s\n",
 			nt_errstr(status));
@@ -355,7 +360,9 @@ static bool lock4_child(const char *lockname,
 		ctx,
 		string_term_tdb_data(lockname),
 		lock_type,
-		(struct timeval) { .tv_sec = 1 });
+		(struct timeval) { .tv_sec = 1 },
+		NULL,
+		NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr, "child: g_lock_lock returned %s\n",
 			nt_errstr(status));
@@ -510,16 +517,18 @@ bool run_g_lock4(int dummy)
 		return false;
 	}
 
-	status = g_lock_lock(
-		ctx, key, G_LOCK_WRITE, (struct timeval) { .tv_usec = 1 });
+	status = g_lock_lock(ctx, key, G_LOCK_WRITE,
+			     (struct timeval) { .tv_usec = 1 },
+			      NULL, NULL);
 	if (!NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT)) {
 		fprintf(stderr, "g_lock_lock returned %s\n",
 			nt_errstr(status));
 		goto fail;
 	}
 
-	status = g_lock_lock(
-		ctx, key, G_LOCK_READ, (struct timeval) { .tv_usec = 1 });
+	status = g_lock_lock(ctx, key, G_LOCK_READ,
+			     (struct timeval) { .tv_usec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT)) {
 		fprintf(stderr, "g_lock_lock returned %s\n",
 			nt_errstr(status));
@@ -633,16 +642,18 @@ bool run_g_lock4a(int dummy)
 		return false;
 	}
 
-	status = g_lock_lock(
-		ctx, key, G_LOCK_WRITE, (struct timeval) { .tv_usec = 1 });
+	status = g_lock_lock(ctx, key, G_LOCK_WRITE,
+			     (struct timeval) { .tv_usec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT)) {
 		fprintf(stderr, "g_lock_lock returned %s\n",
 			nt_errstr(status));
 		goto fail;
 	}
 
-	status = g_lock_lock(
-		ctx, key, G_LOCK_READ, (struct timeval) { .tv_usec = 1 });
+	status = g_lock_lock(ctx, key, G_LOCK_READ,
+			     (struct timeval) { .tv_usec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr, "g_lock_lock returned %s\n",
 			nt_errstr(status));
@@ -778,7 +789,8 @@ bool run_g_lock5(int dummy)
 			status = g_lock_lock(ctx,
 					     string_term_tdb_data(lockname),
 					     G_LOCK_READ,
-					     (struct timeval) { .tv_sec = 1 });
+					     (struct timeval) { .tv_sec = 1 },
+					     NULL, NULL);
 			if (!NT_STATUS_IS_OK(status)) {
 				fprintf(stderr,
 					"child g_lock_lock failed %s\n",
@@ -835,7 +847,8 @@ bool run_g_lock5(int dummy)
 
 		status = g_lock_lock(ctx, string_term_tdb_data(lockname),
 				     G_LOCK_READ,
-				     (struct timeval) { .tv_sec = 1 });
+				     (struct timeval) { .tv_sec = 1 },
+				     NULL, NULL);
 		if (!NT_STATUS_IS_OK(status)) {
 			fprintf(stderr, "g_lock_lock failed %s\n",
 				nt_errstr(status));
@@ -903,7 +916,8 @@ bool run_g_lock6(int dummy)
 	 * CLEAR_IF_FIRST
 	 */
 	status = g_lock_lock(ctx, lockname, G_LOCK_WRITE,
-			     (struct timeval) { .tv_sec = 1 });
+			     (struct timeval) { .tv_sec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr, "g_lock_lock failed: %s\n",
 			nt_errstr(status));
@@ -947,7 +961,8 @@ bool run_g_lock6(int dummy)
 			status = g_lock_lock(ctx,
 					     lockname,
 					     G_LOCK_READ,
-					     (struct timeval) { .tv_sec = 1 });
+					     (struct timeval) { .tv_sec = 1 },
+					     NULL, NULL);
 			if (!NT_STATUS_IS_OK(status)) {
 				fprintf(stderr,
 					"child g_lock_lock failed %s\n",
@@ -1005,7 +1020,8 @@ bool run_g_lock6(int dummy)
 		status = g_lock_lock(ctx,
 				     lockname,
 				     G_LOCK_WRITE,
-				     (struct timeval) { .tv_sec = 1 });
+				     (struct timeval) { .tv_sec = 1 },
+				     NULL, NULL);
 		if (!NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT)) {
 			fprintf(stderr, "g_lock_lock should have failed with %s - %s\n",
 				nt_errstr(NT_STATUS_IO_TIMEOUT),
@@ -1014,7 +1030,8 @@ bool run_g_lock6(int dummy)
 		}
 
 		status = g_lock_lock(ctx, lockname, G_LOCK_READ,
-				     (struct timeval) { .tv_sec = 1 });
+				     (struct timeval) { .tv_sec = 1 },
+				     NULL, NULL);
 		if (!NT_STATUS_IS_OK(status)) {
 			fprintf(stderr, "g_lock_lock failed: %s\n",
 				nt_errstr(status));
@@ -1034,7 +1051,8 @@ bool run_g_lock6(int dummy)
 	}
 
 	status = g_lock_lock(ctx, lockname, G_LOCK_UPGRADE,
-			     (struct timeval) { .tv_sec = 1 });
+			     (struct timeval) { .tv_sec = 1 },
+			     NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr, "g_lock_lock failed: %s\n",
 			nt_errstr(status));
@@ -1102,7 +1120,8 @@ bool run_g_lock7(int dummy)
 			ctx,
 			key,
 			G_LOCK_READ,
-			(struct timeval) { .tv_usec = 1 });
+			(struct timeval) { .tv_usec = 1 },
+			NULL, NULL);
 		if (!NT_STATUS_IS_OK(status)) {
 			fprintf(stderr,
 				"g_lock_lock(READ) failed: %s\n",
@@ -1169,7 +1188,8 @@ bool run_g_lock7(int dummy)
 		ctx,
 		key,
 		G_LOCK_READ,
-		(struct timeval) { .tv_usec = 1 });
+		(struct timeval) { .tv_usec = 1 },
+		NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr,
 			"g_lock_lock(READ) failed: %s\n",
@@ -1194,7 +1214,8 @@ bool run_g_lock7(int dummy)
 		ctx,
 		key,
 		G_LOCK_UPGRADE,
-		(struct timeval) { .tv_sec = 10 });
+		(struct timeval) { .tv_sec = 10 },
+		NULL, NULL);
 	if (!NT_STATUS_EQUAL(status, NT_STATUS_POSSIBLE_DEADLOCK)) {
 		fprintf(stderr,
 			"g_lock_lock returned %s\n",
@@ -1237,7 +1258,8 @@ bool run_g_lock8(int dummy)
 		ctx,
 		lockname,
 		G_LOCK_WRITE,
-		(struct timeval) { .tv_sec = 999 });
+		(struct timeval) { .tv_sec = 999 },
+		NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr,
 			"g_lock_lock failed: %s\n",
@@ -1330,7 +1352,8 @@ bool run_g_lock_ping_pong(int dummy)
 	snprintf(name, sizeof(name), "ping_pong_%d", i);
 
 	status = g_lock_lock(ctx, string_term_tdb_data(name), G_LOCK_WRITE,
-			     (struct timeval) { .tv_sec = 60 });
+			     (struct timeval) { .tv_sec = 60 },
+			     NULL, NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		fprintf(stderr, "g_lock_lock failed: %s\n",
 			nt_errstr(status));
@@ -1343,7 +1366,8 @@ bool run_g_lock_ping_pong(int dummy)
 
 		status = g_lock_lock(ctx, string_term_tdb_data(name),
 				     G_LOCK_WRITE,
-				     (struct timeval) { .tv_sec = 60 });
+				     (struct timeval) { .tv_sec = 60 },
+				     NULL, NULL);
 		if (!NT_STATUS_IS_OK(status)) {
 			fprintf(stderr, "g_lock_lock failed: %s\n",
 				nt_errstr(status));
diff --git a/source3/utils/net_g_lock.c b/source3/utils/net_g_lock.c
index 2a3b105b276..a1000284102 100644
--- a/source3/utils/net_g_lock.c
+++ b/source3/utils/net_g_lock.c
@@ -87,7 +87,9 @@ static int net_g_lock_do(struct net_context *c, int argc, const char **argv)
 		ctx,
 		key,
 		G_LOCK_WRITE,
-		timeval_set(timeout / 1000, timeout % 1000));
+		timeval_set(timeout / 1000, timeout % 1000),
+		NULL,
+		NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		d_fprintf(stderr,
 			  _("g_lock_lock failed: %s\n"),
diff --git a/source3/utils/net_registry.c b/source3/utils/net_registry.c
index 23e1dc0adbd..5d1314ec37a 100644
--- a/source3/utils/net_registry.c
+++ b/source3/utils/net_registry.c
@@ -613,7 +613,12 @@ static int net_registry_increment(struct net_context *c, int argc,
 		goto done;
 	}
 
-	status = g_lock_lock(ctx, lock_key, G_LOCK_WRITE, timeval_set(600, 0));
+	status = g_lock_lock(ctx,
+			     lock_key,
+			     G_LOCK_WRITE,
+			     timeval_set(600, 0),
+			     NULL,
+			     NULL);
 	if (!NT_STATUS_IS_OK(status)) {
 		d_fprintf(stderr, _("g_lock_lock failed: %s\n"),
 			  nt_errstr(status));