SERVER-30242 SERVER-31513 SERVER-31235 Make method to determine if fCV has been initialized in memory. Make fCV state one atomic variable. Initialize fCV on arbiters once a primary is elected.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
index a43c9cb9f49..5df5779ee11 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
@@ -495,8 +495,10 @@ void WiredTigerKVEngine::cleanShutdown() {
             closeConfig = "leak_memory=true";
         }
 
-        const bool needsDowngrade =
-            !_readOnly && !serverGlobalParams.featureCompatibility.isFullyUpgradedTo36();
+        // Only downgrade when the fCV document has been explicitly initialized and is 3.4.
+        const bool needsDowngrade = !_readOnly &&
+            serverGlobalParams.featureCompatibility.isVersionInitialized() &&
+            serverGlobalParams.featureCompatibility.isFullyDowngradedTo34();
 
         invariantWTOK(_conn->close(_conn, closeConfig));
         _conn = nullptr;