locking: Add database priority handling for older versions of samba

In samba versions 3.6.x and older, database priorities are not set.
later_db() function implements higher database priority (locking order)
for these databases -
   brlock, g_lock, notify_onelevel, serverid, xattr_tdb

Signed-off-by: Amitay Isaacs <amitay@gmail.com>

(This used to be ctdb commit edbc8a6669b594d3c413d603e1c9fada9244c2ee)

1 files changed, 61 insertions, 0 deletions

diff --git a/ctdb/server/ctdb_lock.c b/ctdb/server/ctdb_lock.c
index 667c11791c3..fd91c63e890 100644
--- a/ctdb/server/ctdb_lock.c
+++ b/ctdb/server/ctdb_lock.c
@@ -84,6 +84,25 @@ struct lock_request {
 
 
 /*
+ * Support samba 3.6.x (and older) versions which do not set db priority.
+ *
+ * By default, all databases are set to priority 1. So only when priority
+ * is set to 1, check for databases that need higher priority.
+ */
+static bool later_db(const char *name)
+{
+	if (strstr(name, "brlock") ||
+	    strstr(name, "g_lock") ||
+	    strstr(name, "notify_onelevel") ||
+	    strstr(name, "serverid") ||
+	    strstr(name, "xattr_tdb")) {
+		return true;
+	}
+
+	return false;
+}
+
+/*
  * lock all databases
  */
 int ctdb_lockall_prio(struct ctdb_context *ctdb, uint32_t priority)
@@ -94,6 +113,27 @@ int ctdb_lockall_prio(struct ctdb_context *ctdb, uint32_t priority)
 		if (ctdb_db->priority != priority) {
 			continue;
 		}
+		if (later_db(ctdb_db->db_name)) {
+			continue;
+		}
+		DEBUG(DEBUG_INFO, ("locking database %s, priority:%u\n",
+				   ctdb_db->db_name, priority));
+		if (tdb_lockall(ctdb_db->ltdb->tdb) != 0) {
+			DEBUG(DEBUG_ERR, ("Failed to lock database %s\n",
+					  ctdb_db->db_name));
+			return -1;
+		}
+	}
+
+	/* If priority != 1, later_db check is not required and can return */
+	if (priority != 1) {
+		return 0;
+	}
+
+	for (ctdb_db = ctdb->db_list; ctdb_db; ctdb_db = ctdb_db->next) {
+		if (!later_db(ctdb_db->db_name)) {
+			continue;
+		}
 		DEBUG(DEBUG_INFO, ("locking database %s, priority:%u\n",
 				   ctdb_db->db_name, priority));
 		if (tdb_lockall(ctdb_db->ltdb->tdb) != 0) {
@@ -181,6 +221,27 @@ int ctdb_lockall_mark_prio(struct ctdb_context *ctdb, uint32_t priority)
 		if (ctdb_db->priority != priority) {
 			continue;
 		}
+		if (later_db(ctdb_db->db_name)) {
+			continue;
+		}
+		if (tdb_transaction_write_lock_mark(ctdb_db->ltdb->tdb) != 0) {
+			return -1;
+		}
+		if (tdb_lockall_mark(ctdb_db->ltdb->tdb) != 0) {
+			/* FIXME: Shouldn't we unmark here? */
+			return -1;
+		}
+	}
+
+	/* If priority != 1, later_db check is not required and can return */
+	if (priority != 1) {
+		return 0;
+	}
+
+	for (ctdb_db = ctdb->db_list; ctdb_db; ctdb_db = ctdb_db->next) {
+		if (!later_db(ctdb_db->db_name)) {
+			continue;
+		}
 		if (tdb_transaction_write_lock_mark(ctdb_db->ltdb->tdb) != 0) {
 			return -1;
 		}