SERVER-69931 Adapt existing checks to allow distributed transactions into the config DB through the Internal Transactions API

2 files changed, 4 insertions, 2 deletions

diff --git a/src/mongo/db/write_concern.cpp b/src/mongo/db/write_concern.cpp
index d552e4e4ad1..f6caaad89d0 100644
--- a/src/mongo/db/write_concern.cpp
+++ b/src/mongo/db/write_concern.cpp
@@ -146,7 +146,8 @@ StatusWith<WriteConcernOptions> extractWriteConcern(OperationContext* opCtx,
         serverGlobalParams.clusterRole == ClusterRole::ConfigServer &&
         !opCtx->getClient()->isInDirectClient() &&
         (opCtx->getClient()->session() &&
-         (opCtx->getClient()->session()->getTags() & transport::Session::kInternalClient))) {
+         (opCtx->getClient()->session()->getTags() & transport::Session::kInternalClient)) &&
+        !opCtx->inMultiDocumentTransaction()) {
         // Upconvert the writeConcern of any incoming requests from internal connections (i.e.,
         // from other nodes in the cluster) to "majority." This protects against internal code that
         // does not specify writeConcern when writing to the config server.
diff --git a/src/mongo/s/commands/strategy.cpp b/src/mongo/s/commands/strategy.cpp
index e4d3993e61c..89949b35360 100644
--- a/src/mongo/s/commands/strategy.cpp
+++ b/src/mongo/s/commands/strategy.cpp
@@ -80,6 +80,7 @@
 #include "mongo/s/cluster_commands_helpers.h"
 #include "mongo/s/commands/cluster_explain.h"
 #include "mongo/s/grid.h"
+#include "mongo/s/is_mongos.h"
 #include "mongo/s/load_balancer_support.h"
 #include "mongo/s/mongos_topology_coordinator.h"
 #include "mongo/s/query/cluster_cursor_manager.h"
@@ -595,7 +596,7 @@ void ParseAndRunCommand::_parseCommand() {
 
     // TODO SERVER-28756: Change allowTransactionsOnConfigDatabase to true once we fix the bug
     // where the mongos custom write path incorrectly drops the client's txnNumber.
-    auto allowTransactionsOnConfigDatabase = false;
+    auto allowTransactionsOnConfigDatabase = !isMongos();
     validateSessionOptions(*_osi, command->getName(), nss, allowTransactionsOnConfigDatabase);
 
     _wc.emplace(uassertStatusOK(WriteConcernOptions::extractWCFromCommand(request.body)));