1 files changed, 20 insertions, 0 deletions
diff --git a/src/mongo/db/repl/repl_set_request_votes_args.cpp b/src/mongo/db/repl/repl_set_request_votes_args.cpp
index 57256d71554..3c8538606ed 100644
--- a/src/mongo/db/repl/repl_set_request_votes_args.cpp
+++ b/src/mongo/db/repl/repl_set_request_votes_args.cpp
@@ -33,6 +33,7 @@
 #include "mongo/bson/util/bson_extract.h"
 #include "mongo/db/jsobj.h"
 #include "mongo/db/repl/bson_extract_optime.h"
+#include "mongo/db/server_options.h"
 
 namespace mongo {
 namespace repl {
@@ -41,6 +42,7 @@ namespace {
 const std::string kCandidateIndexFieldName = "candidateIndex";
 const std::string kCommandName = "replSetRequestVotes";
 const std::string kConfigVersionFieldName = "configVersion";
+const std::string kConfigTermFieldName = "configTerm";
 const std::string kDryRunFieldName = "dryRun";
 // The underlying field name is inaccurate, but changing it requires a fair amount of cross
 // compatibility work for no real benefit.
@@ -56,6 +58,7 @@ const std::string kLegalArgsFieldNames[] = {
     kCandidateIndexFieldName,
     kCommandName,
     kConfigVersionFieldName,
+    kConfigTermFieldName,
     kDryRunFieldName,
     kLastDurableOpTimeFieldName,
     kSetNameFieldName,
@@ -84,6 +87,13 @@ Status ReplSetRequestVotesArgs::initialize(const BSONObj& argsObj) {
     if (!status.isOK())
         return status;
 
+    // In order to be compatible with FCV 4.2, default the config term to -1 if we are unable
+    // parse a configTerm field from the args.
+    status = bsonExtractIntegerFieldWithDefault(
+        argsObj, kConfigTermFieldName, OpTime::kUninitializedTerm, &_cfgterm);
+    if (!status.isOK())
+        return status;
+
     status = bsonExtractStringField(argsObj, kSetNameFieldName, &_setName);
     if (!status.isOK())
         return status;
@@ -115,6 +125,10 @@ long long ReplSetRequestVotesArgs::getConfigVersion() const {
     return _cfgver;
 }
 
+long long ReplSetRequestVotesArgs::getConfigTerm() const {
+    return _cfgterm;
+}
+
 OpTime ReplSetRequestVotesArgs::getLastDurableOpTime() const {
     return _lastDurableOpTime;
 }
@@ -130,6 +144,12 @@ void ReplSetRequestVotesArgs::addToBSON(BSONObjBuilder* builder) const {
     builder->append(kTermFieldName, _term);
     builder->appendIntOrLL(kCandidateIndexFieldName, _candidateIndex);
     builder->appendIntOrLL(kConfigVersionFieldName, _cfgver);
+    // Only append the config term field if we are in FCV 4.4
+    if (serverGlobalParams.featureCompatibility.isVersionInitialized() &&
+        serverGlobalParams.featureCompatibility.getVersion() ==
+            ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo44) {
+        builder->appendIntOrLL(kConfigTermFieldName, _cfgterm);
+    }
     _lastDurableOpTime.append(builder, kLastDurableOpTimeFieldName);
 }