mon/MDSMonitor: check fscid exists for legacy case

If a client does not have permission to see the legacy fs, the monitor
will throw an exception when looking up the mdsmap later in the code.
We need to check existence for both code paths.

Fixes: https://tracker.ceph.com/issues/51077
Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

diff --git a/src/mon/MDSMonitor.cc b/src/mon/MDSMonitor.cc
index 4af783ba93f85fc9e64aee49ca685badcccca510..07a790fc17907b5a7d4613531a16ff4f94030858 100644 (file)
--- a/src/mon/MDSMonitor.cc
+++ b/src/mon/MDSMonitor.cc
@@ -1755,15 +1755,6 @@ void MDSMonitor::check_sub(Subscription *sub)
                   << "'" << dendl;
           return;
         }
-        if (fsmap.filesystems.count(fscid) == 0) {
-          // Client asked for a non-existent namespace, send them nothing
-          // TODO: something more graceful for when a client has a filesystem
-          // mounted, and the fileysstem is deleted.  Add a "shut down you fool"
-          // flag to MMDSMap?
-          dout(1) << "Client subscribed to non-existent namespace '" <<
-                  fscid << "'" << dendl;
-          return;
-        }
       } else {
         // Unqualified request for "mdsmap": give it the one marked
         // for use by legacy clients.
@@ -1775,6 +1766,15 @@ void MDSMonitor::check_sub(Subscription *sub)
           return;
         }
       }
+      if (!fsmap.filesystem_exists(fscid)) {
+        // Client asked for a non-existent namespace, send them nothing
+        // TODO: something more graceful for when a client has a filesystem
+        // mounted, and the fileysstem is deleted.  Add a "shut down you fool"
+        // flag to MMDSMap?
+        dout(1) << "Client subscribed to non-existent namespace '" <<
+                fscid << "'" << dendl;
+        return;
+      }
     }
     dout(10) << __func__ << ": is_mds=" << is_mds << ", fscid= " << fscid << dendl;