mds: fix daemon selection when starting ranks

Previously, if "standby for rank" was set, but
"standby for fscid" wasn't, the daemon wouldn't
be recognised as the right one for the rank,
and we would end up promoting some arbitrary
standby.

Signed-off-by: John Spray <john.spray@redhat.com>

diff --git a/src/mds/FSMap.cc b/src/mds/FSMap.cc
index bfa97a3d6fd7efe87ea544e297e80b9b7ad3aa2d..53899cadc3e4c4c3d0504e399bdb96f736178476 100644 (file)
--- a/src/mds/FSMap.cc
+++ b/src/mds/FSMap.cc
@@ -541,7 +541,14 @@ mds_gid_t FSMap::find_standby_for(mds_role_t role, const std::string& name) cons
       continue;
     }
 
-    if ((info.standby_for_rank == role.rank && info.standby_for_fscid == role.fscid)
+    // The mds_info_t may or may not tell us exactly which filesystem
+    // the standby_for_rank refers to: lookup via legacy_client_fscid
+    mds_role_t target_role = {
+      info.standby_for_fscid == FS_CLUSTER_ID_NONE ?
+        legacy_client_fscid : info.standby_for_fscid,
+      info.standby_for_rank};
+
+    if ((target_role.rank == role.rank && target_role.fscid == role.fscid)
         || (name.length() && info.standby_for_name == name)) {
       // It's a named standby for *me*, use it.
       return gid;