SERVER-75385 Clean up code from earlier catalog shard design

4 files changed, 14 insertions, 30 deletions

diff --git a/jstests/core/index/hidden_index.js b/jstests/core/index/hidden_index.js
index 572d9016ae0..248b3c7b875 100644
--- a/jstests/core/index/hidden_index.js
+++ b/jstests/core/index/hidden_index.js
@@ -133,11 +133,9 @@ assert.eq(idxSpec.hidden, true);
 const systemColl = db.getSiblingDB("admin").system.version;
 assert.commandWorked(systemColl.createIndex({a: 1}));
 // The collMod command throws NoShardingEnabled on DDL coordinator implementation and BadValue on
-// old implementation. When the config server supports catalog shard mode, it fails with
-// ShardingStateNotInitialized.
-assert.commandFailedWithCode(
-    systemColl.hideIndex("a_1"),
-    [ErrorCodes.NoShardingEnabled, ErrorCodes.BadValue, ErrorCodes.ShardingStateNotInitialized]);
+// old implementation.
+assert.commandFailedWithCode(systemColl.hideIndex("a_1"),
+                             [ErrorCodes.NoShardingEnabled, ErrorCodes.BadValue]);
 assert.commandFailedWithCode(systemColl.createIndex({a: 1}, {hidden: true}), 2);
 
 // Can't hide the '_id' index.
diff --git a/src/mongo/db/ops/insert.cpp b/src/mongo/db/ops/insert.cpp
index a1832c530e7..c7f18b2ab5f 100644
--- a/src/mongo/db/ops/insert.cpp
+++ b/src/mongo/db/ops/insert.cpp
@@ -206,8 +206,7 @@ Status userAllowedCreateNS(OperationContext* opCtx, const NamespaceString& ns) {
                       str::stream() << "Invalid collection name: " << ns.coll());
     }
 
-    if (serverGlobalParams.clusterRole == ClusterRole::ConfigServer && !ns.isOnInternalDb() &&
-        !ShardingState::get(opCtx)->enabled()) {
+    if (serverGlobalParams.clusterRole.isExclusivelyConfigSvrRole() && !ns.isOnInternalDb()) {
         return Status(ErrorCodes::InvalidNamespace,
                       str::stream()
                           << "Can't create user databases on a dedicated --configsvr instance "
diff --git a/src/mongo/db/pipeline/sharded_agg_helpers.cpp b/src/mongo/db/pipeline/sharded_agg_helpers.cpp
index 9381748a04e..2f72457e2b8 100644
--- a/src/mongo/db/pipeline/sharded_agg_helpers.cpp
+++ b/src/mongo/db/pipeline/sharded_agg_helpers.cpp
@@ -1557,13 +1557,8 @@ StatusWith<CollectionRoutingInfo> getExecutionNsRoutingInfo(OperationContext* op
     // a collection before its enclosing database is created. However, if there are no shards
     // present, then $changeStream should immediately return an empty cursor just as other
     // aggregations do when the database does not exist.
-    //
-    // Note despite config.collections always being unsharded, to support $shardedDataDistribution
-    // we always take the shard targeting path. The collection must only exist on the config server,
-    // so even if there are no shards, the query can still succeed and we shouldn't return
-    // ShardNotFound.
     const auto shardIds = Grid::get(opCtx)->shardRegistry()->getAllShardIds(opCtx);
-    if (shardIds.empty() && execNss != NamespaceString::kConfigsvrCollectionsNamespace) {
+    if (shardIds.empty()) {
         return {ErrorCodes::ShardNotFound, "No shards are present in the cluster"};
     }
 
@@ -1644,7 +1639,8 @@ std::unique_ptr<Pipeline, PipelineDeleter> attachCursorToPipeline(
             auto pipelineToTarget = pipeline->clone();
 
             if (!cm.isSharded() &&
-                (gFeatureFlagCatalogShard.isEnabled(serverGlobalParams.featureCompatibility) ||
+                // TODO SERVER-75391: Remove this condition.
+                (serverGlobalParams.clusterRole == ClusterRole::ConfigServer ||
                  expCtx->ns != NamespaceString::kConfigsvrCollectionsNamespace)) {
                 // If the collection is unsharded and we are on the primary, we should be able to
                 // do a local read. The primary may be moved right after the primary shard check,
@@ -1654,9 +1650,9 @@ std::unique_ptr<Pipeline, PipelineDeleter> attachCursorToPipeline(
                 // There is the case where we are in config.collections (collection unsharded) and
                 // we want to broadcast to all shards for the $shardedDataDistribution pipeline. In
                 // this case we don't want to do a local read and we must target the config servers.
-                // If the catalog shard feature flag is enabled in the current FCV, read locally
-                // because all nodes in the cluster should be running a recent enough binary so only
-                // the config server will be targeted for the pipeline.
+                // In 7.0, only the config server will be targeted for this collection, but in a
+                // mixed version cluster, an older binary mongos may still target a shard, so if the
+                // current node is not the config server, we force remote targeting.
                 try {
                     auto expectUnshardedCollection(
                         expCtx->mongoProcessInterface->expectUnshardedCollectionInScope(
diff --git a/src/mongo/db/s/config/sharding_catalog_manager_shard_operations.cpp b/src/mongo/db/s/config/sharding_catalog_manager_shard_operations.cpp
index 560d8e237f7..f27ac525b62 100644
--- a/src/mongo/db/s/config/sharding_catalog_manager_shard_operations.cpp
+++ b/src/mongo/db/s/config/sharding_catalog_manager_shard_operations.cpp
@@ -432,19 +432,10 @@ StatusWith<ShardType> ShardingCatalogManager::_validateHostAsShard(
     }
 
     // Is it a config server?
-    if (resIsMaster.hasField("configsvr")) {
-        if (!isCatalogShard) {
-            return {ErrorCodes::OperationFailed,
-                    str::stream() << "Cannot add " << connectionString.toString()
-                                  << " as a shard since it is a config server"};
-        }
-
-        auto ourSetName = repl::ReplicationCoordinator::get(opCtx)->getSettings().ourSetName();
-        if (providedSetName != ourSetName) {
-            return {ErrorCodes::OperationFailed,
-                    str::stream() << "Cannot add " << connectionString.toString()
-                                  << " as a catalog shard since it is a different config server"};
-        }
+    if (resIsMaster.hasField("configsvr") && !isCatalogShard) {
+        return {ErrorCodes::OperationFailed,
+                str::stream() << "Cannot add " << connectionString.toString()
+                              << " as a shard since it is a config server"};
     }
 
     if (resIsMaster.hasField(HelloCommandReply::kIsImplicitDefaultMajorityWCFieldName) &&