SERVER-46582 Remove FCV checks for safe replica set reconfig

4 files changed, 9 insertions, 45 deletions

diff --git a/src/mongo/db/repl/repl_set_commands.cpp b/src/mongo/db/repl/repl_set_commands.cpp
index 11ff4550d27..e3cfe46a459 100644
--- a/src/mongo/db/repl/repl_set_commands.cpp
+++ b/src/mongo/db/repl/repl_set_commands.cpp
@@ -439,13 +439,8 @@ public:
         uassertStatusOK(status);
 
         // Now that the new config has been persisted and installed in memory, wait for the new
-        // config to become committed. For force reconfigs we don't need to do this waiting, and in
-        // any FCV < 4.4 we also bypass this to preserve client facing behavior in mixed version
-        // sets.
-        if (!parsedArgs.force &&
-            serverGlobalParams.featureCompatibility.isVersion(
-                ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo44) &&
-            enableSafeReplicaSetReconfig) {
+        // config to become committed. For force reconfigs we don't need to do this waiting.
+        if (!parsedArgs.force && enableSafeReplicaSetReconfig) {
             uassertStatusOK(replCoord->awaitConfigCommitment(opCtx));
         }
 
diff --git a/src/mongo/db/repl/repl_set_config_checks.cpp b/src/mongo/db/repl/repl_set_config_checks.cpp
index e55ab04f905..3286b69e46b 100644
--- a/src/mongo/db/repl/repl_set_config_checks.cpp
+++ b/src/mongo/db/repl/repl_set_config_checks.cpp
@@ -363,10 +363,7 @@ StatusWith<int> validateConfigForReconfig(ReplicationCoordinatorExternalState* e
 
     // For non-force reconfigs, verify that the reconfig only adds or removes a single node. This
     // ensures that all quorums of the new config overlap with all quorums of the old config.
-    if (!force &&
-        serverGlobalParams.featureCompatibility.getVersion() ==
-            ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo44 &&
-        enableSafeReplicaSetReconfig) {
+    if (!force && enableSafeReplicaSetReconfig) {
         status = validateSingleNodeChange(oldConfig, newConfig);
         if (!status.isOK()) {
             return StatusWith<int>(status);
diff --git a/src/mongo/db/repl/repl_set_config_checks_test.cpp b/src/mongo/db/repl/repl_set_config_checks_test.cpp
index 9654e9217e0..d68cab85d05 100644
--- a/src/mongo/db/repl/repl_set_config_checks_test.cpp
+++ b/src/mongo/db/repl/repl_set_config_checks_test.cpp
@@ -1103,20 +1103,6 @@ TEST_F(ServiceContextTest, ValidateForReconfig_MultiNodeRemovalDisallowed) {
                   validateMemberReconfig(oldMembers, newMembers, m1));
 }
 
-TEST_F(ServiceContextTest, ValidateForReconfig_MultiNodeAdditionAllowedFCV42) {
-    EnsureFCV fcv{ServerGlobalParams::FeatureCompatibility::Version::kFullyDowngradedTo42};
-    BSONArray oldMembers = BSON_ARRAY(m1 << m2);
-    BSONArray newMembers = BSON_ARRAY(m1 << m2 << m3 << m4);  // add 2 voting nodes.
-    ASSERT_OK(validateMemberReconfig(oldMembers, newMembers, m1));
-}
-
-TEST_F(ServiceContextTest, ValidateForReconfig_MultiNodeRemovalAllowedFCV42) {
-    EnsureFCV fcv{ServerGlobalParams::FeatureCompatibility::Version::kFullyDowngradedTo42};
-    BSONArray oldMembers = BSON_ARRAY(m1 << m2 << m3 << m4);
-    BSONArray newMembers = BSON_ARRAY(m1 << m2);  // remove 2 voting nodes.
-    ASSERT_OK(validateMemberReconfig(oldMembers, newMembers, m1));
-}
-
 TEST_F(ServiceContextTest, ValidateForReconfig_MultiNodeAdditionOfNonVotingNodesAllowed) {
     BSONArray oldMembers = BSON_ARRAY(m1 << m2);
     BSONArray newMembers =
diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index 80d548b7716..16ba689edab 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -3011,10 +3011,7 @@ void ReplicationCoordinatorImpl::cancelAndRescheduleElectionTimeout() {
 
 EventHandle ReplicationCoordinatorImpl::_processReplSetMetadata_inlock(
     const rpc::ReplSetMetadata& replMetadata) {
-    // If we're in FCV 4.4, allow metadata updates between config versions.
-    if (!serverGlobalParams.featureCompatibility.isVersion(
-            ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo44) ||
-        !enableSafeReplicaSetReconfig) {
+    if (!enableSafeReplicaSetReconfig) {
         if (replMetadata.getConfigVersion() != _rsConfig.getConfigVersion()) {
             return EventHandle();
         }
@@ -3125,12 +3122,10 @@ Status ReplicationCoordinatorImpl::processReplSetReconfig(OperationContext* opCt
                             long long currentTerm) -> StatusWith<ReplSetConfig> {
         ReplSetConfig newConfig;
 
-        // Only explicitly set configTerm for reconfig to this node's term if we're in FCV 4.4.
-        // Otherwise, use -1.
-        auto useSafeReconfig = serverGlobalParams.featureCompatibility.isVersion(
-            ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo44);
-        useSafeReconfig = useSafeReconfig && enableSafeReplicaSetReconfig;
-        auto term = (!args.force && useSafeReconfig) ? currentTerm : OpTime::kUninitializedTerm;
+        // Only explicitly set configTerm for reconfig to this node's term if safe reconfig is
+        // enabled. Otherwise, use -1.
+        auto term = (!args.force && enableSafeReplicaSetReconfig) ? currentTerm
+                                                                  : OpTime::kUninitializedTerm;
 
         // When initializing a new config through the replSetReconfig command, ignore the term
         // field passed in through its args. Instead, use this node's term.
@@ -3265,9 +3260,7 @@ Status ReplicationCoordinatorImpl::doReplSetReconfig(OperationContext* opCtx,
     // Construct a fake OpTime that can be accepted but isn't used.
     OpTime fakeOpTime(Timestamp(1, 1), topCoordTerm);
 
-    if (serverGlobalParams.featureCompatibility.isVersion(
-            ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo44) &&
-        !force && enableSafeReplicaSetReconfig) {
+    if (!force && enableSafeReplicaSetReconfig) {
         if (!_doneWaitingForReplication_inlock(fakeOpTime, configWriteConcern)) {
             return Status(ErrorCodes::ConfigurationInProgress,
                           str::stream()
@@ -3814,13 +3807,6 @@ ReplicationCoordinatorImpl::_updateMemberStateFromTopologyCoordinator(WithLock l
                   "Replica set state transition",
                   "newState"_attr = newState,
                   "oldState"_attr = _memberState);
-    // Initializes the featureCompatibilityVersion to the latest value, because arbiters do not
-    // receive the replicated version. This is to avoid bugs like SERVER-32639.
-    if (newState.arbiter()) {
-        serverGlobalParams.featureCompatibility.setVersion(
-            ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo44);
-    }
-
     _memberState = newState;
 
     _cancelAndRescheduleElectionTimeout_inlock();