Revert "SERVER-56846 Fail reconfig for shard server if it would change DWCF and CWWC is not set"r5.0.3-rc2r5.0.3

This reverts commit 081648d6c77cfaab1688ed762aff14c665a72415.

3 files changed, 18 insertions, 206 deletions

diff --git a/buildscripts/resmokeconfig/suites/sharding_continuous_config_stepdown.yml b/buildscripts/resmokeconfig/suites/sharding_continuous_config_stepdown.yml
index 30e5ad0e760..0c5f5d33c9f 100644
--- a/buildscripts/resmokeconfig/suites/sharding_continuous_config_stepdown.yml
+++ b/buildscripts/resmokeconfig/suites/sharding_continuous_config_stepdown.yml
@@ -136,7 +136,6 @@ selector:
   - jstests/sharding/mongos_no_replica_set_refresh.js
   - jstests/sharding/movechunk_interrupt_at_primary_stepdown.js
   - jstests/sharding/primary_config_server_blackholed_from_mongos.js
-  - jstests/sharding/reconfig_fails_no_cwwc_set_sharding.js
   # Nothing is affected by config server step down
   - jstests/sharding/basic_sharding_params.js
   # ShardingTest is never used, so continuous step down thread never starts
diff --git a/jstests/sharding/reconfig_fails_no_cwwc_set_sharding.js b/jstests/sharding/reconfig_fails_no_cwwc_set_sharding.js
deleted file mode 100644
index eb59cd03598..00000000000
--- a/jstests/sharding/reconfig_fails_no_cwwc_set_sharding.js
+++ /dev/null
@@ -1,156 +0,0 @@
-/*
- * Test that a reconfig for a shard that would change the implicit default write concern to w:1
- * fails if CWWC is not set.
- *
- * @tags: [requires_fcv_50, requires_majority_read_concern, requires_persistence]
- */
-
-(function() {
-'use strict';
-
-load("jstests/replsets/rslib.js");  // For reconfig, isConfigCommitted and
-                                    // safeReconfigShouldFail.
-
-const configurationIncompatibleMsg =
-    "config that would change the implicit default write concern on the shard to {w: 1}.";
-
-const configServerUnreachableMsg = "the request to the config server is failing with error:";
-
-let addNodeConfig = function(rst, nodeId, conn, arbiter) {
-    const config = rst.getReplSetConfigFromNode();
-    if (arbiter) {
-        config.members.push({_id: nodeId, host: conn.host, arbiterOnly: true});
-    } else {
-        config.members.push({_id: nodeId, host: conn.host});
-    }
-
-    return config;
-};
-
-let removeNodeConfig = function(rst, conn) {
-    const config = rst.getReplSetConfigFromNode();
-    for (var i = 0; i < config.members.length; i++) {
-        if (config.members[i].host == conn.host) {
-            config.members.splice(i, 1);
-            break;
-        }
-    }
-
-    return config;
-};
-
-function testReconfig(rst, config, shouldSucceed, errCode, errMsg) {
-    if (shouldSucceed) {
-        reconfig(rst, config);
-        assert.soon(() => isConfigCommitted(rst.getPrimary()));
-        rst.waitForConfigReplication(rst.getPrimary());
-        rst.awaitReplication();
-    } else {
-        safeReconfigShouldFail(rst, config, false /* force */, errCode, errMsg);
-
-        // A force reconfig should also fail.
-        safeReconfigShouldFail(rst, config, true /* force */, errCode, errMsg);
-    }
-}
-
-jsTestLog("Testing to reconfig a shard that is not yet added to a sharded cluster.");
-let logPrefix = "While the shard is not part of a sharded cluster: ";
-let shardServer = new ReplSetTest(
-    {name: "shardServer", nodes: 1, nodeOptions: {shardsvr: ""}, useHostName: true});
-shardServer.startSet();
-shardServer.initiate();
-
-jsTestLog(logPrefix + "Adding an arbiter node that will change IDWC to (w:1) should succeed.");
-let arbiter = shardServer.add();
-testReconfig(shardServer,
-             addNodeConfig(shardServer, 1 /* nodeId */, arbiter /* conn */, true /* arbiter */),
-             true /* shouldSucceed */);
-
-jsTestLog(logPrefix +
-          "Removing an arbiter node that will change IDWC to (w: 'Majority') should succeed.");
-shardServer.remove(arbiter);
-testReconfig(shardServer, removeNodeConfig(shardServer, arbiter), true /* shouldSucceed */);
-
-shardServer.stopSet();
-
-jsTestLog("Testing to reconfig a shard that is part of a sharded cluster.");
-logPrefix = "While the shard is part of a sharded cluster: ";
-shardServer = new ReplSetTest(
-    {name: "shardServer", nodes: 1, nodeOptions: {shardsvr: ""}, useHostName: true});
-shardServer.startSet();
-shardServer.initiate();
-
-const st = new ShardingTest({shards: 0, mongos: 1});
-var admin = st.getDB('admin');
-
-jsTestLog("Adding the shard to the cluster should succeed.");
-assert.commandWorked(admin.runCommand({addshard: shardServer.getURL()}));
-
-jsTestLog(logPrefix +
-          "Adding an non-arbiter node that will keep IDWC set to (w: 'Majority') should succeed.");
-testReconfig(
-    shardServer,
-    addNodeConfig(shardServer, 1 /* nodeId */, shardServer.add() /* conn */, false /* arbiter */),
-    true /* shouldSucceed */);
-
-jsTestLog(logPrefix + "Adding an arbiter node that will change IDWC to (w:1) should fail.");
-arbiter = shardServer.add();
-testReconfig(shardServer,
-             addNodeConfig(shardServer, 2 /* nodeId */, arbiter /* conn */, true /* arbiter */),
-             false /* shouldSucceed */,
-             ErrorCodes.NewReplicaSetConfigurationIncompatible,
-             configurationIncompatibleMsg);
-
-jsTestLog("Setting the CWWC on the cluster.");
-logPrefix = "While CWWC is set on the sharded cluster: ";
-assert.commandWorked(
-    st.s.adminCommand({setDefaultRWConcern: 1, defaultWriteConcern: {w: "majority", wtimeout: 0}}));
-
-jsTestLog(logPrefix + "Adding an arbiter node that will change IDWC to (w:1) should succeed.");
-testReconfig(shardServer,
-             addNodeConfig(shardServer, 2 /* nodeId */, arbiter /* conn */, true /* arbiter */),
-             true /* shouldSucceed */);
-
-jsTestLog("Testing when the config server is unreachable.");
-logPrefix = "While config server is unreachable: ";
-jsTestLog("Shutting down all config servers");
-for (var i = 0; i < st.configRS.nodes.length; i++) {
-    st.stopConfigServer(i);
-}
-st.configRS.awaitNoPrimary();
-
-// The reason why this is okay is because CWWC had to have been set for the cluster to get to this
-// point, even if we can't check the config servers for it.
-jsTestLog(logPrefix +
-          "Removing an arbiter node that will change IDWC to (w: 'Majority') should succeed.");
-shardServer.remove(arbiter);
-testReconfig(shardServer, removeNodeConfig(shardServer, arbiter), true /* shouldSucceed */);
-
-jsTestLog(logPrefix + "Adding an arbiter node that will change IDWC to (w: 1) should fail.");
-testReconfig(shardServer,
-             addNodeConfig(shardServer, 2 /* nodeId */, arbiter /* conn */, true /* arbiter */),
-             false /* shouldSucceed */,
-             ErrorCodes.ConfigServerUnreachable,
-             configServerUnreachableMsg);
-
-jsTestLog("Restarting the config servers.");
-logPrefix = "While the config server is reachable: ";
-for (var i = 0; i < st.configRS.nodes.length; i++) {
-    st.restartConfigServer(i, undefined, undefined, true /* wait */);
-}
-st.configRS.awaitNodesAgreeOnPrimary();
-print("Sleeping for 60 seconds to let the other shards restart their ReplicaSetMonitors");
-sleep(60000);
-
-jsTestLog(logPrefix + "Adding an arbiter node will change IDWC to (w:1) should succeed.");
-arbiter = shardServer.add();
-testReconfig(shardServer,
-             addNodeConfig(shardServer, 2 /* nodeId */, arbiter /* conn */, true /* arbiter */),
-             true /* shouldSucceed */);
-
-jsTestLog("Stopping the cluster.");
-st.stop();
-
-jsTestLog("Stopping the shard.");
-shardServer.stopSet();
-})();
\ No newline at end of file
diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index f63f9b90ece..69b769e0cc6 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -3467,57 +3467,26 @@ Status ReplicationCoordinatorImpl::_doReplSetReconfig(OperationContext* opCtx,
         return status;
     ReplSetConfig newConfig = newConfigStatus.getValue();
 
-    // Excluding reconfigs that bump the config term during step-up from checking against changing
-    // the implicit default write concern, as it is not needed.
-    if (!skipSafetyChecks /* skipping step-up reconfig */) {
+    // If the new config changes the replica set's implicit default write concern, we fail the
+    // reconfig command. This includes force reconfigs, but excludes reconfigs that bump the config
+    // term during step-up. The user should set a cluster-wide write concern and attempt the
+    // reconfig command again. We also need to exclude shard servers from this validation, as shard
+    // servers don't store the cluster-wide write concern.
+    if (!skipSafetyChecks /* skipping step-up reconfig */ &&
+        repl::feature_flags::gDefaultWCMajority.isEnabled(
+            serverGlobalParams.featureCompatibility) &&
+        serverGlobalParams.clusterRole != ClusterRole::ShardServer &&
+        !repl::enableDefaultWriteConcernUpdatesForInitiate.load()) {
         bool currIDWC = oldConfig.isImplicitDefaultWriteConcernMajority();
         bool newIDWC = newConfig.isImplicitDefaultWriteConcernMajority();
-
-        // If the new config changes the replica set's implicit default write concern, we fail the
-        // reconfig command. This includes force reconfigs.
-        // The user should set a cluster-wide write concern and attempt the reconfig command again.
-        if (serverGlobalParams.clusterRole != ClusterRole::ShardServer) {
-            if (repl::feature_flags::gDefaultWCMajority.isEnabled(
-                    serverGlobalParams.featureCompatibility) &&
-                !repl::enableDefaultWriteConcernUpdatesForInitiate.load() && currIDWC != newIDWC &&
-                !ReadWriteConcernDefaults::get(opCtx).isCWWCSet(opCtx)) {
-                return Status(
-                    ErrorCodes::NewReplicaSetConfigurationIncompatible,
-                    str::stream()
-                        << "Reconfig attempted to install a config that would change the implicit "
-                           "default write concern. Use the setDefaultRWConcern command to set a "
-                           "cluster-wide write concern and try the reconfig again.");
-            }
-        } else {
-            // Allow all reconfigs if the shard is not part of a sharded cluster yet, however
-            // prevent changing the implicit default write concern to (w: 1) after it becomes part
-            // of a sharded cluster and CWWC is not set on the cluster.
-            // Remote call to the configServer should be done to check if CWWC is set on the
-            // cluster.
-            if (_externalState->isShardPartOfShardedCluster(opCtx) && currIDWC != newIDWC &&
-                !newIDWC) {
-                try {
-                    // Initiates a remote call to the config server.
-                    if (!_externalState->isCWWCSetOnConfigShard(opCtx)) {
-                        return Status(
-                            ErrorCodes::NewReplicaSetConfigurationIncompatible,
-                            str::stream()
-                                << "Reconfig attempted to install a config that would change the "
-                                   "implicit default write concern on the shard to {w: 1}. Use the "
-                                   "setDefaultRWConcern command to set a cluster-wide write "
-                                   "concern on the cluster and try the reconfig again.");
-                    }
-                } catch (const DBException& ex) {
-                    return Status(
-                        ErrorCodes::ConfigServerUnreachable,
-                        str::stream()
-                            << "Reconfig attempted to install a config that would change the "
-                               "implicit default write concern on the shard to {w: 1}, but the "
-                               "shard can not check if CWWC is set on the cluster, as the request "
-                               "to the config server is failing with error: " +
-                                ex.toString());
-                }
-            }
+        bool isCWWCSet = ReadWriteConcernDefaults::get(opCtx).isCWWCSet(opCtx);
+        if (!isCWWCSet && currIDWC != newIDWC) {
+            return Status(
+                ErrorCodes::NewReplicaSetConfigurationIncompatible,
+                str::stream()
+                    << "Reconfig attempted to install a config that would change the "
+                       "implicit default write concern. Use the setDefaultRWConcern command to "
+                       "set a cluster-wide write concern and try the reconfig again.");
         }
     }