SERVER-19875 Add OperationContext to CatalogManager::getAllShards

69 files changed, 469 insertions, 397 deletions

diff --git a/src/mongo/client/parallel.cpp b/src/mongo/client/parallel.cpp
index f35e4fe2662..169a233ab5e 100644
--- a/src/mongo/client/parallel.cpp
+++ b/src/mongo/client/parallel.cpp
@@ -457,43 +457,6 @@ BSONObj ParallelConnectionMetadata::toBSON() const {
                         << "init" << initialized << "finish" << finished << "errored" << errored);
 }
 
-BSONObj ParallelSortClusteredCursor::toBSON() const {
-    BSONObjBuilder b;
-
-    b.append("tries", _totalTries);
-
-    {
-        BSONObjBuilder bb;
-        for (map<ShardId, PCMData>::const_iterator i = _cursorMap.begin(), end = _cursorMap.end();
-             i != end;
-             ++i) {
-            const auto shard = grid.shardRegistry()->getShard(i->first);
-            if (!shard) {
-                continue;
-            }
-
-            bb.append(shard->toString(), i->second.toBSON());
-        }
-        b.append("cursors", bb.obj().getOwned());
-    }
-
-    {
-        BSONObjBuilder bb;
-        for (map<string, int>::const_iterator i = _staleNSMap.begin(), end = _staleNSMap.end();
-             i != end;
-             ++i) {
-            bb.append(i->first, i->second);
-        }
-        b.append("staleTries", bb.obj().getOwned());
-    }
-
-    return b.obj().getOwned();
-}
-
-string ParallelSortClusteredCursor::toString() const {
-    return str::stream() << "PCursor : " << toBSON();
-}
-
 void ParallelSortClusteredCursor::fullInit(OperationContext* txn) {
     startInit(txn);
     finishInit(txn);
@@ -546,7 +509,8 @@ void ParallelSortClusteredCursor::_handleStaleNS(OperationContext* txn,
     }
 }
 
-void ParallelSortClusteredCursor::setupVersionAndHandleSlaveOk(PCStatePtr state,
+void ParallelSortClusteredCursor::setupVersionAndHandleSlaveOk(OperationContext* txn,
+                                                               PCStatePtr state,
                                                                const ShardId& shardId,
                                                                std::shared_ptr<Shard> primary,
                                                                const NamespaceString& ns,
@@ -562,7 +526,7 @@ void ParallelSortClusteredCursor::setupVersionAndHandleSlaveOk(PCStatePtr state,
 
     // Setup conn
     if (!state->conn) {
-        const auto shard = grid.shardRegistry()->getShard(shardId);
+        const auto shard = grid.shardRegistry()->getShard(txn, shardId);
         state->conn.reset(new ShardConnection(shard->getConnString(), ns.ns(), manager));
     }
 
@@ -653,7 +617,7 @@ void ParallelSortClusteredCursor::startInit(OperationContext* txn) {
         auto status = grid.catalogCache()->getDatabase(txn, nss.db().toString());
         if (status.getStatus().code() != ErrorCodes::DatabaseNotFound) {
             config = uassertStatusOK(status);
-            config->getChunkManagerOrPrimary(nss.ns(), manager, primary);
+            config->getChunkManagerOrPrimary(txn, nss.ns(), manager, primary);
         }
     }
 
@@ -735,7 +699,7 @@ void ParallelSortClusteredCursor::startInit(OperationContext* txn) {
             mdata.pcState.reset(new PCState());
             PCStatePtr state = mdata.pcState;
 
-            setupVersionAndHandleSlaveOk(state, shardId, primary, nss, vinfo, manager);
+            setupVersionAndHandleSlaveOk(txn, state, shardId, primary, nss, vinfo, manager);
 
             const string& ns = _qSpec.ns();
 
@@ -1127,7 +1091,7 @@ void ParallelSortClusteredCursor::finishInit(OperationContext* txn) {
         _cursors[index].reset(mdata.pcState->cursor.get(), &mdata);
 
         {
-            const auto shard = grid.shardRegistry()->getShard(i->first);
+            const auto shard = grid.shardRegistry()->getShard(txn, i->first);
             _servers.insert(shard->getConnString().toString());
         }
 
@@ -1153,8 +1117,8 @@ int ParallelSortClusteredCursor::getNumQueryShards() {
     return _cursorMap.size();
 }
 
-std::shared_ptr<Shard> ParallelSortClusteredCursor::getQueryShard() {
-    return grid.shardRegistry()->getShard(_cursorMap.begin()->first);
+ShardId ParallelSortClusteredCursor::getQueryShardId() {
+    return _cursorMap.begin()->first;
 }
 
 void ParallelSortClusteredCursor::getQueryShardIds(set<ShardId>& shardIds) {
diff --git a/src/mongo/client/parallel.h b/src/mongo/client/parallel.h
index bfb6c115123..ac507d91eca 100644
--- a/src/mongo/client/parallel.h
+++ b/src/mongo/client/parallel.h
@@ -194,7 +194,7 @@ public:
      * Returns the single shard with an open cursor.
      * It is an error to call this if getNumQueryShards() > 1
      */
-    std::shared_ptr<Shard> getQueryShard();
+    ShardId getQueryShardId();
 
     /**
      * Returns primary shard with an open cursor.
@@ -204,9 +204,6 @@ public:
 
     DBClientCursorPtr getShardCursor(const ShardId& shardId);
 
-    BSONObj toBSON() const;
-    std::string toString() const;
-
     void explain(BSONObjBuilder& b);
 
 private:
@@ -251,7 +248,8 @@ private:
      * set connection and the primary cannot be reached, the version
      * will not be set if the slaveOk flag is set.
      */
-    void setupVersionAndHandleSlaveOk(PCStatePtr state /* in & out */,
+    void setupVersionAndHandleSlaveOk(OperationContext* txn,
+                                      PCStatePtr state /* in & out */,
                                       const ShardId& shardId,
                                       std::shared_ptr<Shard> primary /* in */,
                                       const NamespaceString& ns,
diff --git a/src/mongo/db/s/metadata_loader.cpp b/src/mongo/db/s/metadata_loader.cpp
index b6a5aee155e..9a0823fb0b3 100644
--- a/src/mongo/db/s/metadata_loader.cpp
+++ b/src/mongo/db/s/metadata_loader.cpp
@@ -66,11 +66,11 @@ public:
         return chunk.getShard() == _currShard;
     }
 
-    virtual pair<BSONObj, BSONObj> rangeFor(const ChunkType& chunk) const {
+    virtual pair<BSONObj, BSONObj> rangeFor(OperationContext* txn, const ChunkType& chunk) const {
         return make_pair(chunk.getMin(), chunk.getMax());
     }
 
-    virtual string shardFor(const string& name) const {
+    virtual string shardFor(OperationContext* txn, const string& name) const {
         return name;
     }
 
@@ -193,7 +193,7 @@ Status MetadataLoader::initChunks(OperationContext* txn,
         // last time).  If not, something has changed on the config server (potentially between
         // when we read the collection data and when we read the chunks data).
         //
-        int diffsApplied = differ.calculateConfigDiff(chunks);
+        int diffsApplied = differ.calculateConfigDiff(txn, chunks);
         if (diffsApplied > 0) {
             // Chunks found, return ok
             LOG(2) << "loaded " << diffsApplied << " chunks into new metadata for " << ns
diff --git a/src/mongo/s/SConscript b/src/mongo/s/SConscript
index 8de255b7b2d..7a1662cc32b 100644
--- a/src/mongo/s/SConscript
+++ b/src/mongo/s/SConscript
@@ -59,6 +59,7 @@ env.CppUnitTest(
     ],
     LIBDEPS=[
         'common',
+        '$BUILD_DIR/mongo/db/service_context',
     ]
 )
 
diff --git a/src/mongo/s/balance.cpp b/src/mongo/s/balance.cpp
index d9234b7f116..5971e9b04cf 100644
--- a/src/mongo/s/balance.cpp
+++ b/src/mongo/s/balance.cpp
@@ -213,7 +213,7 @@ void Balancer::_ping(OperationContext* txn, bool waiting) {
                                      NULL);
 }
 
-bool Balancer::_checkOIDs() {
+bool Balancer::_checkOIDs(OperationContext* txn) {
     vector<ShardId> all;
     grid.shardRegistry()->getAllShardIds(&all);
 
@@ -221,7 +221,7 @@ bool Balancer::_checkOIDs() {
     map<int, string> oids;
 
     for (const ShardId& shardId : all) {
-        const auto s = grid.shardRegistry()->getShard(shardId);
+        const auto s = grid.shardRegistry()->getShard(txn, shardId);
         if (!s) {
             continue;
         }
@@ -242,7 +242,7 @@ bool Balancer::_checkOIDs() {
                 uassertStatusOK(grid.shardRegistry()->runCommand(
                     shardHost, "admin", BSON("features" << 1 << "oidReset" << 1)));
 
-                const auto otherShard = grid.shardRegistry()->getShard(oids[x]);
+                const auto otherShard = grid.shardRegistry()->getShard(txn, oids[x]);
                 if (otherShard) {
                     const auto otherShardHost = uassertStatusOK(otherShard->getTargeter()->findHost(
                         {ReadPreference::PrimaryOnly, TagSet::primaryOnly()}));
@@ -439,7 +439,7 @@ void Balancer::_doBalanceRound(OperationContext* txn,
     }
 }
 
-bool Balancer::_init() {
+bool Balancer::_init(OperationContext* txn) {
     try {
         log() << "about to contact config servers and shards";
 
@@ -447,8 +447,8 @@ bool Balancer::_init() {
         // checks that each shard is indeed a different process (no hostname mixup)
         // these checks are redundant in that they're redone at every new round but we want to do
         // them initially here so to catch any problem soon
-        grid.shardRegistry()->reload();
-        _checkOIDs();
+        grid.shardRegistry()->reload(txn);
+        _checkOIDs(txn);
 
         log() << "config servers and shards contacted successfully";
 
@@ -474,7 +474,8 @@ void Balancer::run() {
     // This is the body of a BackgroundJob so if we throw here we're basically ending the balancer
     // thread prematurely.
     while (!inShutdown()) {
-        if (!_init()) {
+        auto txn = cc().makeOperationContext();
+        if (!_init(txn.get())) {
             log() << "will retry to initialize balancer in one minute";
             sleepsecs(60);
             continue;
@@ -501,7 +502,7 @@ void Balancer::run() {
             BSONObj balancerResult;
 
             // use fresh shard state
-            grid.shardRegistry()->reload();
+            grid.shardRegistry()->reload(txn.get());
 
             // refresh chunk size (even though another balancer might be active)
             Chunk::refreshChunkSize(txn.get());
@@ -529,7 +530,7 @@ void Balancer::run() {
                 continue;
             }
 
-            uassert(13258, "oids broken after resetting!", _checkOIDs());
+            uassert(13258, "oids broken after resetting!", _checkOIDs(txn.get()));
 
             {
                 auto scopedDistLock = grid.catalogManager(txn.get())
diff --git a/src/mongo/s/balance.h b/src/mongo/s/balance.h
index 27b9d217640..861508c96e3 100644
--- a/src/mongo/s/balance.h
+++ b/src/mongo/s/balance.h
@@ -83,7 +83,7 @@ private:
      *
      * This method throws on a network exception
      */
-    bool _init();
+    bool _init(OperationContext* txn);
 
     /**
      * Gathers all the necessary information about shards and chunks, and decides whether there are
@@ -118,7 +118,7 @@ private:
      * @return true if all the servers listed in configdb as being shards are reachable and are
      *         distinct processes
      */
-    bool _checkOIDs();
+    bool _checkOIDs(OperationContext* txn);
 };
 
 extern Balancer balancer;
diff --git a/src/mongo/s/balancer_policy.cpp b/src/mongo/s/balancer_policy.cpp
index 55aa205dfd7..1b81d8b3ec5 100644
--- a/src/mongo/s/balancer_policy.cpp
+++ b/src/mongo/s/balancer_policy.cpp
@@ -66,8 +66,10 @@ namespace {
  *  ShardNotFound if shard by that id is not available on the registry
  *  NoSuchKey if the version could not be retrieved
  */
-std::string retrieveShardMongoDVersion(ShardId shardId, ShardRegistry* shardRegistry) {
-    auto shard = shardRegistry->getShard(shardId);
+std::string retrieveShardMongoDVersion(OperationContext* txn,
+                                       ShardId shardId,
+                                       ShardRegistry* shardRegistry) {
+    auto shard = shardRegistry->getShard(txn, shardId);
     if (!shard) {
         uassertStatusOK({ErrorCodes::ShardNotFound, "Shard not found"});
     }
@@ -276,7 +278,7 @@ void DistributionStatus::dump() const {
 Status DistributionStatus::populateShardInfoMap(OperationContext* txn, ShardInfoMap* shardInfo) {
     try {
         vector<ShardType> shards;
-        Status status = grid.catalogManager(txn)->getAllShards(&shards);
+        Status status = grid.catalogManager(txn)->getAllShards(txn, &shards);
         if (!status.isOK()) {
             return status;
         }
@@ -285,10 +287,10 @@ Status DistributionStatus::populateShardInfoMap(OperationContext* txn, ShardInfo
             std::set<std::string> dummy;
 
             const long long shardSizeBytes = uassertStatusOK(
-                shardutil::retrieveTotalShardSize(shardData.getName(), grid.shardRegistry()));
+                shardutil::retrieveTotalShardSize(txn, shardData.getName(), grid.shardRegistry()));
 
             const std::string shardMongodVersion =
-                retrieveShardMongoDVersion(shardData.getName(), grid.shardRegistry());
+                retrieveShardMongoDVersion(txn, shardData.getName(), grid.shardRegistry());
 
             ShardInfo newShardEntry(shardData.getMaxSizeMB(),
                                     shardSizeBytes / 1024 / 1024,
diff --git a/src/mongo/s/catalog/catalog_manager.h b/src/mongo/s/catalog/catalog_manager.h
index 8548368ed49..2241de16392 100644
--- a/src/mongo/s/catalog/catalog_manager.h
+++ b/src/mongo/s/catalog/catalog_manager.h
@@ -286,7 +286,7 @@ public:
      * Retrieves all shards in this sharded cluster.
      * Returns a !OK status if an error occurs.
      */
-    virtual Status getAllShards(std::vector<ShardType>* shards) = 0;
+    virtual Status getAllShards(OperationContext* txn, std::vector<ShardType>* shards) = 0;
 
     /**
      * Runs a user management command on the config servers, potentially synchronizing through
diff --git a/src/mongo/s/catalog/catalog_manager_common.cpp b/src/mongo/s/catalog/catalog_manager_common.cpp
index 2d82b767c12..ebdff4f5d1d 100644
--- a/src/mongo/s/catalog/catalog_manager_common.cpp
+++ b/src/mongo/s/catalog/catalog_manager_common.cpp
@@ -330,7 +330,7 @@ StatusWith<string> CatalogManagerCommon::addShard(OperationContext* txn,
 
     // If a name for a shard wasn't provided, generate one
     if (shardType.getName().empty()) {
-        StatusWith<string> result = _generateNewShardName();
+        StatusWith<string> result = _generateNewShardName(txn);
         if (!result.isOK()) {
             return Status(ErrorCodes::OperationFailed, "error generating new shard name");
         }
@@ -351,7 +351,7 @@ StatusWith<string> CatalogManagerCommon::addShard(OperationContext* txn,
     }
 
     // Make sure the new shard is visible
-    grid.shardRegistry()->reload();
+    grid.shardRegistry()->reload(txn);
 
     // Add all databases which were discovered on the new shard
     for (const string& dbName : dbNamesStatus.getValue()) {
@@ -437,13 +437,13 @@ Status CatalogManagerCommon::createDatabase(OperationContext* txn, const std::st
     }
 
     // check for case sensitivity violations
-    Status status = _checkDbDoesNotExist(dbName, nullptr);
+    Status status = _checkDbDoesNotExist(txn, dbName, nullptr);
     if (!status.isOK()) {
         return status;
     }
 
     // Database does not exist, pick a shard and create a new entry
-    auto newShardIdStatus = selectShardForNewDatabase(grid.shardRegistry());
+    auto newShardIdStatus = selectShardForNewDatabase(txn, grid.shardRegistry());
     if (!newShardIdStatus.isOK()) {
         return newShardIdStatus.getStatus();
     }
@@ -468,12 +468,13 @@ Status CatalogManagerCommon::createDatabase(OperationContext* txn, const std::st
 }
 
 // static
-StatusWith<ShardId> CatalogManagerCommon::selectShardForNewDatabase(ShardRegistry* shardRegistry) {
+StatusWith<ShardId> CatalogManagerCommon::selectShardForNewDatabase(OperationContext* txn,
+                                                                    ShardRegistry* shardRegistry) {
     vector<ShardId> allShardIds;
 
     shardRegistry->getAllShardIds(&allShardIds);
     if (allShardIds.empty()) {
-        shardRegistry->reload();
+        shardRegistry->reload(txn);
         shardRegistry->getAllShardIds(&allShardIds);
 
         if (allShardIds.empty()) {
@@ -483,7 +484,8 @@ StatusWith<ShardId> CatalogManagerCommon::selectShardForNewDatabase(ShardRegistr
 
     ShardId candidateShardId = allShardIds[0];
 
-    auto candidateSizeStatus = shardutil::retrieveTotalShardSize(candidateShardId, shardRegistry);
+    auto candidateSizeStatus =
+        shardutil::retrieveTotalShardSize(txn, candidateShardId, shardRegistry);
     if (!candidateSizeStatus.isOK()) {
         return candidateSizeStatus.getStatus();
     }
@@ -491,7 +493,7 @@ StatusWith<ShardId> CatalogManagerCommon::selectShardForNewDatabase(ShardRegistr
     for (size_t i = 1; i < allShardIds.size(); i++) {
         const ShardId shardId = allShardIds[i];
 
-        const auto sizeStatus = shardutil::retrieveTotalShardSize(shardId, shardRegistry);
+        const auto sizeStatus = shardutil::retrieveTotalShardSize(txn, shardId, shardRegistry);
         if (!sizeStatus.isOK()) {
             return sizeStatus.getStatus();
         }
@@ -519,10 +521,10 @@ Status CatalogManagerCommon::enableSharding(OperationContext* txn, const std::st
     }
 
     // Check for case sensitivity violations
-    Status status = _checkDbDoesNotExist(dbName, &db);
+    Status status = _checkDbDoesNotExist(txn, dbName, &db);
     if (status.isOK()) {
         // Database does not exist, create a new entry
-        auto newShardIdStatus = selectShardForNewDatabase(grid.shardRegistry());
+        auto newShardIdStatus = selectShardForNewDatabase(txn, grid.shardRegistry());
         if (!newShardIdStatus.isOK()) {
             return newShardIdStatus.getStatus();
         }
diff --git a/src/mongo/s/catalog/catalog_manager_common.h b/src/mongo/s/catalog/catalog_manager_common.h
index 42bd0a00f33..3c82e2684fd 100644
--- a/src/mongo/s/catalog/catalog_manager_common.h
+++ b/src/mongo/s/catalog/catalog_manager_common.h
@@ -70,7 +70,8 @@ protected:
      * Selects an optimal shard on which to place a newly created database from the set of
      * available shards. Will return ShardNotFound if shard could not be found.
      */
-    static StatusWith<ShardId> selectShardForNewDatabase(ShardRegistry* shardRegistry);
+    static StatusWith<ShardId> selectShardForNewDatabase(OperationContext* txn,
+                                                         ShardRegistry* shardRegistry);
 
     CatalogManagerCommon() = default;
 
@@ -85,12 +86,14 @@ private:
      *  NamespaceExists if it exists with the same casing
      *  DatabaseDifferCase if it exists under different casing.
      */
-    virtual Status _checkDbDoesNotExist(const std::string& dbName, DatabaseType* db) = 0;
+    virtual Status _checkDbDoesNotExist(OperationContext* txn,
+                                        const std::string& dbName,
+                                        DatabaseType* db) = 0;
 
     /**
      * Generates a unique name to be given to a newly added shard.
      */
-    virtual StatusWith<std::string> _generateNewShardName() = 0;
+    virtual StatusWith<std::string> _generateNewShardName(OperationContext* txn) = 0;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/s/catalog/catalog_manager_mock.cpp b/src/mongo/s/catalog/catalog_manager_mock.cpp
index ee4bba4f8ff..160cdb35e62 100644
--- a/src/mongo/s/catalog/catalog_manager_mock.cpp
+++ b/src/mongo/s/catalog/catalog_manager_mock.cpp
@@ -132,7 +132,7 @@ StatusWith<string> CatalogManagerMock::getTagForChunk(OperationContext* txn,
     return string();
 }
 
-Status CatalogManagerMock::getAllShards(vector<ShardType>* shards) {
+Status CatalogManagerMock::getAllShards(OperationContext* txn, vector<ShardType>* shards) {
     return Status::OK();
 }
 
@@ -185,11 +185,13 @@ DistLockManager* CatalogManagerMock::getDistLockManager() {
     return _mockDistLockMgr.get();
 }
 
-Status CatalogManagerMock::_checkDbDoesNotExist(const std::string& dbName, DatabaseType* db) {
+Status CatalogManagerMock::_checkDbDoesNotExist(OperationContext* txn,
+                                                const std::string& dbName,
+                                                DatabaseType* db) {
     return Status::OK();
 }
 
-StatusWith<std::string> CatalogManagerMock::_generateNewShardName() {
+StatusWith<std::string> CatalogManagerMock::_generateNewShardName(OperationContext* txn) {
     return {ErrorCodes::InternalError, "Method not implemented"};
 }
 
diff --git a/src/mongo/s/catalog/catalog_manager_mock.h b/src/mongo/s/catalog/catalog_manager_mock.h
index 9e183842af2..de697f195a2 100644
--- a/src/mongo/s/catalog/catalog_manager_mock.h
+++ b/src/mongo/s/catalog/catalog_manager_mock.h
@@ -104,7 +104,7 @@ public:
                                            const std::string& collectionNs,
                                            const ChunkType& chunk) override;
 
-    Status getAllShards(std::vector<ShardType>* shards) override;
+    Status getAllShards(OperationContext* txn, std::vector<ShardType>* shards) override;
 
     bool runUserManagementWriteCommand(OperationContext* txn,
                                        const std::string& commandName,
@@ -146,9 +146,11 @@ public:
     Status initConfigVersion(OperationContext* txn) override;
 
 private:
-    Status _checkDbDoesNotExist(const std::string& dbName, DatabaseType* db) override;
+    Status _checkDbDoesNotExist(OperationContext* txn,
+                                const std::string& dbName,
+                                DatabaseType* db) override;
 
-    StatusWith<std::string> _generateNewShardName() override;
+    StatusWith<std::string> _generateNewShardName(OperationContext* txn) override;
 
     std::unique_ptr<DistLockManagerMock> _mockDistLockMgr;
 };
diff --git a/src/mongo/s/catalog/dist_lock_catalog_impl.cpp b/src/mongo/s/catalog/dist_lock_catalog_impl.cpp
index 432b96494a5..b67a0472e43 100644
--- a/src/mongo/s/catalog/dist_lock_catalog_impl.cpp
+++ b/src/mongo/s/catalog/dist_lock_catalog_impl.cpp
@@ -157,7 +157,7 @@ DistLockCatalogImpl::DistLockCatalogImpl(ShardRegistry* shardRegistry,
 DistLockCatalogImpl::~DistLockCatalogImpl() = default;
 
 RemoteCommandTargeter* DistLockCatalogImpl::_targeter() {
-    return _client->getShard("config")->getTargeter();
+    return _client->getConfigShard()->getTargeter();
 }
 
 StatusWith<LockpingsType> DistLockCatalogImpl::getPing(StringData processID) {
@@ -203,8 +203,8 @@ Status DistLockCatalogImpl::ping(StringData processID, Date_t ping) {
     request.setUpsert(true);
     request.setWriteConcern(_writeConcern);
 
-    auto resultStatus = _client->runCommandWithNotMasterRetries(
-        "config", _locksNS.db().toString(), request.toBSON());
+    auto resultStatus =
+        _client->runCommandOnConfigWithNotMasterRetries(_locksNS.db().toString(), request.toBSON());
 
     if (!resultStatus.isOK()) {
         return resultStatus.getStatus();
@@ -234,8 +234,8 @@ StatusWith<LocksType> DistLockCatalogImpl::grabLock(StringData lockID,
     request.setShouldReturnNew(true);
     request.setWriteConcern(_writeConcern);
 
-    auto resultStatus = _client->runCommandWithNotMasterRetries(
-        "config", _locksNS.db().toString(), request.toBSON());
+    auto resultStatus =
+        _client->runCommandOnConfigWithNotMasterRetries(_locksNS.db().toString(), request.toBSON());
 
     if (!resultStatus.isOK()) {
         return resultStatus.getStatus();
@@ -287,8 +287,8 @@ StatusWith<LocksType> DistLockCatalogImpl::overtakeLock(StringData lockID,
     request.setShouldReturnNew(true);
     request.setWriteConcern(_writeConcern);
 
-    auto resultStatus = _client->runCommandWithNotMasterRetries(
-        "config", _locksNS.db().toString(), request.toBSON());
+    auto resultStatus =
+        _client->runCommandOnConfigWithNotMasterRetries(_locksNS.db().toString(), request.toBSON());
 
     if (!resultStatus.isOK()) {
         return resultStatus.getStatus();
@@ -319,8 +319,8 @@ Status DistLockCatalogImpl::unlock(const OID& lockSessionID) {
         BSON("$set" << BSON(LocksType::state(LocksType::UNLOCKED))));
     request.setWriteConcern(_writeConcern);
 
-    auto resultStatus = _client->runCommandWithNotMasterRetries(
-        "config", _locksNS.db().toString(), request.toBSON());
+    auto resultStatus =
+        _client->runCommandOnConfigWithNotMasterRetries(_locksNS.db().toString(), request.toBSON());
 
     if (!resultStatus.isOK()) {
         return resultStatus.getStatus();
@@ -448,8 +448,8 @@ Status DistLockCatalogImpl::stopPing(StringData processId) {
         FindAndModifyRequest::makeRemove(_lockPingNS, BSON(LockpingsType::process() << processId));
     request.setWriteConcern(_writeConcern);
 
-    auto resultStatus = _client->runCommandWithNotMasterRetries(
-        "config", _locksNS.db().toString(), request.toBSON());
+    auto resultStatus =
+        _client->runCommandOnConfigWithNotMasterRetries(_locksNS.db().toString(), request.toBSON());
 
     if (!resultStatus.isOK()) {
         return resultStatus.getStatus();
diff --git a/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp b/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp
index b9fe304530e..e635a8f2554 100644
--- a/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp
+++ b/src/mongo/s/catalog/dist_lock_catalog_impl_test.cpp
@@ -88,7 +88,7 @@ public:
     }
 
     RemoteCommandTargeterMock* targeter() {
-        return RemoteCommandTargeterMock::get(_shardRegistry->getShard("config")->getTargeter());
+        return RemoteCommandTargeterMock::get(_shardRegistry->getConfigShard()->getTargeter());
     }
 
     DistLockCatalogImpl* catalog() {
diff --git a/src/mongo/s/catalog/forwarding_catalog_manager.cpp b/src/mongo/s/catalog/forwarding_catalog_manager.cpp
index a3fae98e0ed..83701165426 100644
--- a/src/mongo/s/catalog/forwarding_catalog_manager.cpp
+++ b/src/mongo/s/catalog/forwarding_catalog_manager.cpp
@@ -286,11 +286,12 @@ StatusWith<std::string> ForwardingCatalogManager::getTagForChunk(OperationContex
     return retry([&] { return _actual->getTagForChunk(txn, collectionNs, chunk); });
 }
 
-Status ForwardingCatalogManager::getAllShards(std::vector<ShardType>* shards) {
+Status ForwardingCatalogManager::getAllShards(OperationContext* txn,
+                                              std::vector<ShardType>* shards) {
     invariant(shards->empty());
     return retry([&] {
         shards->clear();
-        return _actual->getAllShards(shards);
+        return _actual->getAllShards(txn, shards);
     });
 }
 
diff --git a/src/mongo/s/catalog/forwarding_catalog_manager.h b/src/mongo/s/catalog/forwarding_catalog_manager.h
index 69d67658dcb..7ee3740df66 100644
--- a/src/mongo/s/catalog/forwarding_catalog_manager.h
+++ b/src/mongo/s/catalog/forwarding_catalog_manager.h
@@ -139,7 +139,7 @@ public:
                                            const std::string& collectionNs,
                                            const ChunkType& chunk) override;
 
-    Status getAllShards(std::vector<ShardType>* shards) override;
+    Status getAllShards(OperationContext* txn, std::vector<ShardType>* shards) override;
 
     bool runUserManagementWriteCommand(OperationContext* txn,
                                        const std::string& commandName,
diff --git a/src/mongo/s/catalog/legacy/catalog_manager_legacy.cpp b/src/mongo/s/catalog/legacy/catalog_manager_legacy.cpp
index ccf6b7a2bb7..dce58700e54 100644
--- a/src/mongo/s/catalog/legacy/catalog_manager_legacy.cpp
+++ b/src/mongo/s/catalog/legacy/catalog_manager_legacy.cpp
@@ -300,7 +300,7 @@ Status CatalogManagerLegacy::shardCollection(OperationContext* txn,
     collectionDetail.append("collection", ns);
     string dbPrimaryShardStr;
     {
-        const auto shard = grid.shardRegistry()->getShard(dbPrimaryShardId);
+        const auto shard = grid.shardRegistry()->getShard(txn, dbPrimaryShardId);
         dbPrimaryShardStr = shard->toString();
     }
     collectionDetail.append("primary", dbPrimaryShardStr);
@@ -341,7 +341,7 @@ Status CatalogManagerLegacy::shardCollection(OperationContext* txn,
         }
 
         try {
-            const auto shard = grid.shardRegistry()->getShard(dbPrimaryShardId);
+            const auto shard = grid.shardRegistry()->getShard(txn, dbPrimaryShardId);
             ShardConnection conn(shard->getConnString(), ns);
             bool isVersionSet = conn.setVersion();
             conn.done();
@@ -401,7 +401,7 @@ StatusWith<ShardDrainingStatus> CatalogManagerLegacy::removeShard(OperationConte
             return status;
         }
 
-        grid.shardRegistry()->reload();
+        grid.shardRegistry()->reload(txn);
         conn.done();
 
         // Record start in changelog
@@ -431,7 +431,7 @@ StatusWith<ShardDrainingStatus> CatalogManagerLegacy::removeShard(OperationConte
         }
 
         grid.shardRegistry()->remove(name);
-        grid.shardRegistry()->reload();
+        grid.shardRegistry()->reload(txn);
         conn.done();
 
         // Record finish in changelog
@@ -540,7 +540,7 @@ Status CatalogManagerLegacy::dropCollection(OperationContext* txn, const Namespa
         txn, txn->getClient()->clientAddress(true), "dropCollection.start", ns.ns(), BSONObj());
 
     vector<ShardType> allShards;
-    Status status = getAllShards(&allShards);
+    Status status = getAllShards(txn, &allShards);
     if (!status.isOK()) {
         return status;
     }
@@ -560,7 +560,7 @@ Status CatalogManagerLegacy::dropCollection(OperationContext* txn, const Namespa
 
     for (const auto& shardEntry : allShards) {
         auto dropResult = shardRegistry->runCommandWithNotMasterRetries(
-            shardEntry.getName(), ns.db().toString(), BSON("drop" << ns.coll()));
+            txn, shardEntry.getName(), ns.db().toString(), BSON("drop" << ns.coll()));
 
         if (!dropResult.isOK()) {
             return dropResult.getStatus();
@@ -625,7 +625,7 @@ Status CatalogManagerLegacy::dropCollection(OperationContext* txn, const Namespa
             true);
 
         auto ssvResult = shardRegistry->runCommandWithNotMasterRetries(
-            shardEntry.getName(), "admin", ssv.toBSON());
+            txn, shardEntry.getName(), "admin", ssv.toBSON());
 
         if (!ssvResult.isOK()) {
             return ssvResult.getStatus();
@@ -637,7 +637,7 @@ Status CatalogManagerLegacy::dropCollection(OperationContext* txn, const Namespa
         }
 
         auto unsetShardingStatus = shardRegistry->runCommandWithNotMasterRetries(
-            shardEntry.getName(), "admin", BSON("unsetSharding" << 1));
+            txn, shardEntry.getName(), "admin", BSON("unsetSharding" << 1));
 
         if (!unsetShardingStatus.isOK()) {
             return unsetShardingStatus.getStatus();
@@ -918,7 +918,7 @@ StatusWith<string> CatalogManagerLegacy::getTagForChunk(OperationContext* txn,
     return status.getStatus();
 }
 
-Status CatalogManagerLegacy::getAllShards(vector<ShardType>* shards) {
+Status CatalogManagerLegacy::getAllShards(OperationContext* txn, vector<ShardType>* shards) {
     ScopedDbConnection conn(_configServerConnectionString, 30.0);
     std::unique_ptr<DBClientCursor> cursor(
         _safeCursor(conn->query(ShardType::ConfigNS, BSONObj())));
@@ -1118,7 +1118,9 @@ void CatalogManagerLegacy::writeConfigServerDirect(OperationContext* txn,
     exec.executeBatch(request, response);
 }
 
-Status CatalogManagerLegacy::_checkDbDoesNotExist(const std::string& dbName, DatabaseType* db) {
+Status CatalogManagerLegacy::_checkDbDoesNotExist(OperationContext* txn,
+                                                  const std::string& dbName,
+                                                  DatabaseType* db) {
     ScopedDbConnection conn(_configServerConnectionString, 30);
 
     BSONObjBuilder b;
@@ -1153,7 +1155,7 @@ Status CatalogManagerLegacy::_checkDbDoesNotExist(const std::string& dbName, Dat
     return Status::OK();
 }
 
-StatusWith<string> CatalogManagerLegacy::_generateNewShardName() {
+StatusWith<string> CatalogManagerLegacy::_generateNewShardName(OperationContext* txn) {
     BSONObj o;
     {
         ScopedDbConnection conn(_configServerConnectionString, 30);
diff --git a/src/mongo/s/catalog/legacy/catalog_manager_legacy.h b/src/mongo/s/catalog/legacy/catalog_manager_legacy.h
index 70e0a9d69aa..214929f132f 100644
--- a/src/mongo/s/catalog/legacy/catalog_manager_legacy.h
+++ b/src/mongo/s/catalog/legacy/catalog_manager_legacy.h
@@ -101,7 +101,7 @@ public:
                                            const std::string& collectionNs,
                                            const ChunkType& chunk) override;
 
-    Status getAllShards(std::vector<ShardType>* shards) override;
+    Status getAllShards(OperationContext* txn, std::vector<ShardType>* shards) override;
 
     /**
      * Grabs a distributed lock and runs the command on all config servers.
@@ -146,9 +146,11 @@ public:
     Status initConfigVersion(OperationContext* txn) override;
 
 private:
-    Status _checkDbDoesNotExist(const std::string& dbName, DatabaseType* db) override;
+    Status _checkDbDoesNotExist(OperationContext* txn,
+                                const std::string& dbName,
+                                DatabaseType* db) override;
 
-    StatusWith<std::string> _generateNewShardName() override;
+    StatusWith<std::string> _generateNewShardName(OperationContext* txn) override;
 
     /**
      * Starts the thread that periodically checks data consistency amongst the config servers.
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set.cpp b/src/mongo/s/catalog/replset/catalog_manager_replica_set.cpp
index a093c63b8ab..8878f4fd68e 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set.cpp
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set.cpp
@@ -148,7 +148,7 @@ Status CatalogManagerReplicaSet::shardCollection(OperationContext* txn,
     }
 
     ShardId dbPrimaryShardId = status.getValue().value.getPrimary();
-    const auto primaryShard = grid.shardRegistry()->getShard(dbPrimaryShardId);
+    const auto primaryShard = grid.shardRegistry()->getShard(txn, dbPrimaryShardId);
 
     {
         // In 3.0 and prior we include this extra safety check that the collection is not getting
@@ -157,7 +157,7 @@ Status CatalogManagerReplicaSet::shardCollection(OperationContext* txn,
         // toes.  Now we take the distributed lock so going forward this check won't be necessary
         // but we leave it around for compatibility with other mongoses from 3.0.
         // TODO(spencer): Remove this after 3.2 ships.
-        const auto configShard = grid.shardRegistry()->getShard("config");
+        const auto configShard = grid.shardRegistry()->getShard(txn, "config");
         const auto readHost = configShard->getTargeter()->findHost(kConfigReadSelector);
         if (!readHost.isOK()) {
             return readHost.getStatus();
@@ -219,7 +219,7 @@ Status CatalogManagerReplicaSet::shardCollection(OperationContext* txn,
         true);
 
     auto ssvStatus = grid.shardRegistry()->runCommandWithNotMasterRetries(
-        dbPrimaryShardId, "admin", ssv.toBSON());
+        txn, dbPrimaryShardId, "admin", ssv.toBSON());
     if (!ssvStatus.isOK()) {
         warning() << "could not update initial version of " << ns << " on shard primary "
                   << dbPrimaryShardId << ssvStatus.getStatus();
@@ -236,7 +236,7 @@ Status CatalogManagerReplicaSet::shardCollection(OperationContext* txn,
 
 StatusWith<ShardDrainingStatus> CatalogManagerReplicaSet::removeShard(OperationContext* txn,
                                                                       const std::string& name) {
-    const auto configShard = grid.shardRegistry()->getShard("config");
+    const auto configShard = grid.shardRegistry()->getShard(txn, "config");
     const auto readHost = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHost.isOK()) {
         return readHost.getStatus();
@@ -288,7 +288,7 @@ StatusWith<ShardDrainingStatus> CatalogManagerReplicaSet::removeShard(OperationC
             return status;
         }
 
-        grid.shardRegistry()->reload();
+        grid.shardRegistry()->reload(txn);
 
         // Record start in changelog
         logChange(txn,
@@ -333,7 +333,7 @@ StatusWith<ShardDrainingStatus> CatalogManagerReplicaSet::removeShard(OperationC
     }
 
     grid.shardRegistry()->remove(name);
-    grid.shardRegistry()->reload();
+    grid.shardRegistry()->reload(txn);
 
     // Record finish in changelog
     logChange(txn, txn->getClient()->clientAddress(true), "removeShard", "", BSON("shard" << name));
@@ -355,7 +355,7 @@ StatusWith<OpTimePair<DatabaseType>> CatalogManagerReplicaSet::getDatabase(
         return OpTimePair<DatabaseType>(dbt);
     }
 
-    const auto configShard = grid.shardRegistry()->getShard("config");
+    const auto configShard = grid.shardRegistry()->getShard(txn, "config");
     const auto readHost = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHost.isOK()) {
         return readHost.getStatus();
@@ -387,7 +387,7 @@ StatusWith<OpTimePair<DatabaseType>> CatalogManagerReplicaSet::getDatabase(
 
 StatusWith<OpTimePair<CollectionType>> CatalogManagerReplicaSet::getCollection(
     OperationContext* txn, const std::string& collNs) {
-    auto configShard = grid.shardRegistry()->getShard("config");
+    auto configShard = grid.shardRegistry()->getShard(txn, "config");
 
     auto readHostStatus = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHostStatus.isOK()) {
@@ -431,7 +431,7 @@ Status CatalogManagerReplicaSet::getCollections(OperationContext* txn,
                       string(str::stream() << "^" << pcrecpp::RE::QuoteMeta(*dbName) << "\\."));
     }
 
-    auto configShard = grid.shardRegistry()->getShard("config");
+    auto configShard = grid.shardRegistry()->getShard(txn, "config");
     auto readHost = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHost.isOK()) {
         return readHost.getStatus();
@@ -473,7 +473,7 @@ Status CatalogManagerReplicaSet::dropCollection(OperationContext* txn, const Nam
         txn, txn->getClient()->clientAddress(true), "dropCollection.start", ns.ns(), BSONObj());
 
     vector<ShardType> allShards;
-    Status status = getAllShards(&allShards);
+    Status status = getAllShards(txn, &allShards);
     if (!status.isOK()) {
         return status;
     }
@@ -493,7 +493,7 @@ Status CatalogManagerReplicaSet::dropCollection(OperationContext* txn, const Nam
 
     for (const auto& shardEntry : allShards) {
         auto dropResult = shardRegistry->runCommandWithNotMasterRetries(
-            shardEntry.getName(), ns.db().toString(), BSON("drop" << ns.coll()));
+            txn, shardEntry.getName(), ns.db().toString(), BSON("drop" << ns.coll()));
 
         if (!dropResult.isOK()) {
             return dropResult.getStatus();
@@ -563,7 +563,7 @@ Status CatalogManagerReplicaSet::dropCollection(OperationContext* txn, const Nam
             true);
 
         auto ssvResult = shardRegistry->runCommandWithNotMasterRetries(
-            shardEntry.getName(), "admin", ssv.toBSON());
+            txn, shardEntry.getName(), "admin", ssv.toBSON());
 
         if (!ssvResult.isOK()) {
             return ssvResult.getStatus();
@@ -575,7 +575,7 @@ Status CatalogManagerReplicaSet::dropCollection(OperationContext* txn, const Nam
         }
 
         auto unsetShardingStatus = shardRegistry->runCommandWithNotMasterRetries(
-            shardEntry.getName(), "admin", BSON("unsetSharding" << 1));
+            txn, shardEntry.getName(), "admin", BSON("unsetSharding" << 1));
 
         if (!unsetShardingStatus.isOK()) {
             return unsetShardingStatus.getStatus();
@@ -667,7 +667,7 @@ void CatalogManagerReplicaSet::logChange(OperationContext* txn,
 
 StatusWith<SettingsType> CatalogManagerReplicaSet::getGlobalSettings(OperationContext* txn,
                                                                      const string& key) {
-    const auto configShard = grid.shardRegistry()->getShard("config");
+    const auto configShard = grid.shardRegistry()->getShard(txn, "config");
     const auto readHost = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHost.isOK()) {
         return readHost.getStatus();
@@ -709,7 +709,7 @@ StatusWith<SettingsType> CatalogManagerReplicaSet::getGlobalSettings(OperationCo
 Status CatalogManagerReplicaSet::getDatabasesForShard(OperationContext* txn,
                                                       const string& shardName,
                                                       vector<string>* dbs) {
-    auto configShard = grid.shardRegistry()->getShard("config");
+    auto configShard = grid.shardRegistry()->getShard(txn, "config");
     auto readHost = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHost.isOK()) {
         return readHost.getStatus();
@@ -746,7 +746,7 @@ Status CatalogManagerReplicaSet::getChunks(OperationContext* txn,
                                            OpTime* opTime) {
     chunks->clear();
 
-    auto configShard = grid.shardRegistry()->getShard("config");
+    auto configShard = grid.shardRegistry()->getShard(txn, "config");
     auto readHostStatus = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHostStatus.isOK()) {
         return readHostStatus.getStatus();
@@ -786,7 +786,7 @@ Status CatalogManagerReplicaSet::getTagsForCollection(OperationContext* txn,
                                                       std::vector<TagsType>* tags) {
     tags->clear();
 
-    auto configShard = grid.shardRegistry()->getShard("config");
+    auto configShard = grid.shardRegistry()->getShard(txn, "config");
     auto readHostStatus = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHostStatus.isOK()) {
         return readHostStatus.getStatus();
@@ -818,7 +818,7 @@ Status CatalogManagerReplicaSet::getTagsForCollection(OperationContext* txn,
 StatusWith<string> CatalogManagerReplicaSet::getTagForChunk(OperationContext* txn,
                                                             const std::string& collectionNs,
                                                             const ChunkType& chunk) {
-    auto configShard = grid.shardRegistry()->getShard("config");
+    auto configShard = grid.shardRegistry()->getShard(txn, "config");
     auto readHostStatus = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHostStatus.isOK()) {
         return readHostStatus.getStatus();
@@ -850,8 +850,8 @@ StatusWith<string> CatalogManagerReplicaSet::getTagForChunk(OperationContext* tx
     return tagsResult.getValue().getTag();
 }
 
-Status CatalogManagerReplicaSet::getAllShards(vector<ShardType>* shards) {
-    const auto configShard = grid.shardRegistry()->getShard("config");
+Status CatalogManagerReplicaSet::getAllShards(OperationContext* txn, vector<ShardType>* shards) {
+    const auto configShard = grid.shardRegistry()->getShard(txn, "config");
     const auto readHost = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHost.isOK()) {
         return readHost.getStatus();
@@ -908,14 +908,14 @@ bool CatalogManagerReplicaSet::runReadCommand(OperationContext* txn,
     cmdBuilder.appendElements(cmdObj);
     _appendReadConcern(&cmdBuilder);
 
-    return _runReadCommand(dbname, cmdBuilder.done(), kConfigReadSelector, result);
+    return _runReadCommand(txn, dbname, cmdBuilder.done(), kConfigReadSelector, result);
 }
 
 bool CatalogManagerReplicaSet::runUserManagementReadCommand(OperationContext* txn,
                                                             const std::string& dbname,
                                                             const BSONObj& cmdObj,
                                                             BSONObjBuilder* result) {
-    return _runReadCommand(dbname, cmdObj, kConfigPrimaryPreferredSelector, result);
+    return _runReadCommand(txn, dbname, cmdObj, kConfigPrimaryPreferredSelector, result);
 }
 
 Status CatalogManagerReplicaSet::applyChunkOpsDeprecated(OperationContext* txn,
@@ -964,12 +964,14 @@ void CatalogManagerReplicaSet::writeConfigServerDirect(OperationContext* txn,
     }
 }
 
-Status CatalogManagerReplicaSet::_checkDbDoesNotExist(const string& dbName, DatabaseType* db) {
+Status CatalogManagerReplicaSet::_checkDbDoesNotExist(OperationContext* txn,
+                                                      const string& dbName,
+                                                      DatabaseType* db) {
     BSONObjBuilder queryBuilder;
     queryBuilder.appendRegex(
         DatabaseType::name(), (string) "^" + pcrecpp::RE::QuoteMeta(dbName) + "$", "i");
 
-    const auto configShard = grid.shardRegistry()->getShard("config");
+    const auto configShard = grid.shardRegistry()->getShard(txn, "config");
     const auto readHost = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHost.isOK()) {
         return readHost.getStatus();
@@ -1010,8 +1012,8 @@ Status CatalogManagerReplicaSet::_checkDbDoesNotExist(const string& dbName, Data
                                 << " have: " << actualDbName << " want to add: " << dbName);
 }
 
-StatusWith<std::string> CatalogManagerReplicaSet::_generateNewShardName() {
-    const auto configShard = grid.shardRegistry()->getShard("config");
+StatusWith<std::string> CatalogManagerReplicaSet::_generateNewShardName(OperationContext* txn) {
+    const auto configShard = grid.shardRegistry()->getShard(txn, "config");
     const auto readHost = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHost.isOK()) {
         return readHost.getStatus();
@@ -1083,7 +1085,7 @@ StatusWith<long long> CatalogManagerReplicaSet::_runCountCommandOnConfig(const H
 }
 
 Status CatalogManagerReplicaSet::initConfigVersion(OperationContext* txn) {
-    auto versionStatus = _getConfigVersion();
+    auto versionStatus = _getConfigVersion(txn);
     if (!versionStatus.isOK()) {
         return versionStatus.getStatus();
     }
@@ -1130,8 +1132,8 @@ Status CatalogManagerReplicaSet::initConfigVersion(OperationContext* txn) {
     return Status::OK();
 }
 
-StatusWith<VersionType> CatalogManagerReplicaSet::_getConfigVersion() {
-    const auto configShard = grid.shardRegistry()->getShard("config");
+StatusWith<VersionType> CatalogManagerReplicaSet::_getConfigVersion(OperationContext* txn) {
+    const auto configShard = grid.shardRegistry()->getShard(txn, "config");
     const auto readHostStatus = configShard->getTargeter()->findHost(kConfigReadSelector);
     if (!readHostStatus.isOK()) {
         return readHostStatus.getStatus();
@@ -1214,8 +1216,8 @@ StatusWith<BSONObj> CatalogManagerReplicaSet::_runCommandOnConfig(const HostAndP
 
 StatusWith<BSONObj> CatalogManagerReplicaSet::_runCommandOnConfigWithNotMasterRetries(
     const std::string& dbName, BSONObj cmdObj) {
-    auto result = grid.shardRegistry()->runCommandWithNotMasterRetries(
-        "config", dbName, cmdObj, kReplMetadata);
+    auto result =
+        grid.shardRegistry()->runCommandOnConfigWithNotMasterRetries(dbName, cmdObj, kReplMetadata);
 
     if (!result.isOK()) {
         return result.getStatus();
@@ -1270,11 +1272,12 @@ void CatalogManagerReplicaSet::_appendReadConcern(BSONObjBuilder* builder) {
     readConcern.appendInfo(builder);
 }
 
-bool CatalogManagerReplicaSet::_runReadCommand(const std::string& dbname,
+bool CatalogManagerReplicaSet::_runReadCommand(OperationContext* txn,
+                                               const std::string& dbname,
                                                const BSONObj& cmdObj,
                                                const ReadPreferenceSetting& settings,
                                                BSONObjBuilder* result) {
-    auto targeter = grid.shardRegistry()->getShard("config")->getTargeter();
+    auto targeter = grid.shardRegistry()->getShard(txn, "config")->getTargeter();
     auto target = targeter->findHost(settings);
     if (!target.isOK()) {
         return Command::appendCommandStatus(*result, target.getStatus());
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set.h b/src/mongo/s/catalog/replset/catalog_manager_replica_set.h
index 3a9b6c51171..faa603090eb 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set.h
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set.h
@@ -98,7 +98,7 @@ public:
                                            const std::string& collectionNs,
                                            const ChunkType& chunk) override;
 
-    Status getAllShards(std::vector<ShardType>* shards) override;
+    Status getAllShards(OperationContext* txn, std::vector<ShardType>* shards) override;
 
     bool runUserManagementWriteCommand(OperationContext* txn,
                                        const std::string& commandName,
@@ -140,11 +140,14 @@ public:
     Status initConfigVersion(OperationContext* txn) override;
 
 private:
-    Status _checkDbDoesNotExist(const std::string& dbName, DatabaseType* db) override;
+    Status _checkDbDoesNotExist(OperationContext* txn,
+                                const std::string& dbName,
+                                DatabaseType* db) override;
 
-    StatusWith<std::string> _generateNewShardName() override;
+    StatusWith<std::string> _generateNewShardName(OperationContext* txn) override;
 
-    bool _runReadCommand(const std::string& dbname,
+    bool _runReadCommand(OperationContext* txn,
+                         const std::string& dbname,
                          const BSONObj& cmdObj,
                          const ReadPreferenceSetting& settings,
                          BSONObjBuilder* result);
@@ -179,7 +182,7 @@ private:
     /**
      * Returns the current cluster schema/protocol version.
      */
-    StatusWith<VersionType> _getConfigVersion();
+    StatusWith<VersionType> _getConfigVersion(OperationContext* txn);
 
     /**
      * Returns the highest last known config server opTime.
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set_drop_coll_test.cpp b/src/mongo/s/catalog/replset/catalog_manager_replica_set_drop_coll_test.cpp
index e2af5b8393f..1bc870462b1 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set_drop_coll_test.cpp
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set_drop_coll_test.cpp
@@ -79,11 +79,11 @@ public:
         setupShards({_shard1, _shard2});
 
         RemoteCommandTargeterMock* shard1Targeter = RemoteCommandTargeterMock::get(
-            shardRegistry()->getShard(_shard1.getName())->getTargeter());
+            shardRegistry()->getShard(operationContext(), _shard1.getName())->getTargeter());
         shard1Targeter->setFindHostReturnValue(HostAndPort(_shard1.getHost()));
 
         RemoteCommandTargeterMock* shard2Targeter = RemoteCommandTargeterMock::get(
-            shardRegistry()->getShard(_shard2.getName())->getTargeter());
+            shardRegistry()->getShard(operationContext(), _shard2.getName())->getTargeter());
         shard2Targeter->setFindHostReturnValue(HostAndPort(_shard2.getHost()));
     }
 
@@ -293,7 +293,7 @@ TEST_F(DropColl2ShardTest, DistLockBusy) {
 
 TEST_F(DropColl2ShardTest, FirstShardTargeterError) {
     RemoteCommandTargeterMock* shard1Targeter = RemoteCommandTargeterMock::get(
-        shardRegistry()->getShard(shard1().getName())->getTargeter());
+        shardRegistry()->getShard(operationContext(), shard1().getName())->getTargeter());
     shard1Targeter->setFindHostReturnValue({ErrorCodes::HostUnreachable, "bad test network"});
 
     auto future = launchAsync([this] {
@@ -369,7 +369,7 @@ TEST_F(DropColl2ShardTest, FirstShardDropCmdError) {
 
 TEST_F(DropColl2ShardTest, SecondShardTargeterError) {
     RemoteCommandTargeterMock* shard2Targeter = RemoteCommandTargeterMock::get(
-        shardRegistry()->getShard(shard2().getHost())->getTargeter());
+        shardRegistry()->getShard(operationContext(), shard2().getHost())->getTargeter());
     shard2Targeter->setFindHostReturnValue({ErrorCodes::HostUnreachable, "bad test network"});
 
     auto future = launchAsync([this] {
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set_shard_collection_test.cpp b/src/mongo/s/catalog/replset/catalog_manager_replica_set_shard_collection_test.cpp
index 64788d58b38..b31279c7411 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set_shard_collection_test.cpp
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set_shard_collection_test.cpp
@@ -332,7 +332,8 @@ TEST_F(ShardCollectionTest, noInitialChunksOrData) {
 
     setupShards(vector<ShardType>{shard});
 
-    RemoteCommandTargeterMock::get(grid.shardRegistry()->getShard(shard.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        grid.shardRegistry()->getShard(operationContext(), shard.getName())->getTargeter())
         ->setFindHostReturnValue(shardHost);
 
     string ns = "db1.foo";
@@ -459,11 +460,14 @@ TEST_F(ShardCollectionTest, withInitialChunks) {
 
     setupShards(vector<ShardType>{shard0, shard1, shard2});
 
-    RemoteCommandTargeterMock::get(grid.shardRegistry()->getShard(shard0.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        grid.shardRegistry()->getShard(operationContext(), shard0.getName())->getTargeter())
         ->setFindHostReturnValue(shard0Host);
-    RemoteCommandTargeterMock::get(grid.shardRegistry()->getShard(shard1.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        grid.shardRegistry()->getShard(operationContext(), shard1.getName())->getTargeter())
         ->setFindHostReturnValue(shard1Host);
-    RemoteCommandTargeterMock::get(grid.shardRegistry()->getShard(shard2.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        grid.shardRegistry()->getShard(operationContext(), shard2.getName())->getTargeter())
         ->setFindHostReturnValue(shard2Host);
 
     string ns = "db1.foo";
@@ -628,7 +632,8 @@ TEST_F(ShardCollectionTest, withInitialData) {
 
     setupShards(vector<ShardType>{shard});
 
-    RemoteCommandTargeterMock::get(grid.shardRegistry()->getShard(shard.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        grid.shardRegistry()->getShard(operationContext(), shard.getName())->getTargeter())
         ->setFindHostReturnValue(shardHost);
 
     string ns = "db1.foo";
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test.cpp b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test.cpp
index 3cbf3cc1cd9..805bc5fa737 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test.cpp
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test.cpp
@@ -323,7 +323,7 @@ TEST_F(CatalogManagerReplSetTest, GetAllShardsValid) {
 
     auto future = launchAsync([this] {
         vector<ShardType> shards;
-        ASSERT_OK(catalogManager()->getAllShards(&shards));
+        ASSERT_OK(catalogManager()->getAllShards(operationContext(), &shards));
         return shards;
     });
 
@@ -358,7 +358,7 @@ TEST_F(CatalogManagerReplSetTest, GetAllShardsWithInvalidShard) {
 
     auto future = launchAsync([this] {
         vector<ShardType> shards;
-        Status status = catalogManager()->getAllShards(&shards);
+        Status status = catalogManager()->getAllShards(operationContext(), &shards);
 
         ASSERT_EQ(ErrorCodes::FailedToParse, status);
         ASSERT_EQ(0U, shards.size());
@@ -1496,7 +1496,7 @@ TEST_F(CatalogManagerReplSetTest, createDatabaseSuccess) {
     s2.setHost("ShardHost2:27017");
 
     // Prime the shard registry with information about the existing shards
-    auto future = launchAsync([this] { shardRegistry()->reload(); });
+    auto future = launchAsync([this] { shardRegistry()->reload(operationContext()); });
 
     onFindCommand([&](const RemoteCommandRequest& request) {
         ASSERT_EQUALS(configHost, request.target);
@@ -1518,11 +1518,14 @@ TEST_F(CatalogManagerReplSetTest, createDatabaseSuccess) {
     future.timed_get(kFutureTimeout);
 
     // Set up all the target mocks return values.
-    RemoteCommandTargeterMock::get(shardRegistry()->getShard(s0.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        shardRegistry()->getShard(operationContext(), s0.getName())->getTargeter())
         ->setFindHostReturnValue(HostAndPort(s0.getHost()));
-    RemoteCommandTargeterMock::get(shardRegistry()->getShard(s1.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        shardRegistry()->getShard(operationContext(), s1.getName())->getTargeter())
         ->setFindHostReturnValue(HostAndPort(s1.getHost()));
-    RemoteCommandTargeterMock::get(shardRegistry()->getShard(s2.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        shardRegistry()->getShard(operationContext(), s2.getName())->getTargeter())
         ->setFindHostReturnValue(HostAndPort(s2.getHost()));
 
 
@@ -1781,7 +1784,7 @@ TEST_F(CatalogManagerReplSetTest, createDatabaseDuplicateKeyOnInsert) {
     s2.setHost("ShardHost2:27017");
 
     // Prime the shard registry with information about the existing shards
-    auto future = launchAsync([this] { shardRegistry()->reload(); });
+    auto future = launchAsync([this] { shardRegistry()->reload(operationContext()); });
 
     onFindCommand([&](const RemoteCommandRequest& request) {
         ASSERT_EQUALS(configHost, request.target);
@@ -1802,11 +1805,14 @@ TEST_F(CatalogManagerReplSetTest, createDatabaseDuplicateKeyOnInsert) {
     future.timed_get(kFutureTimeout);
 
     // Set up all the target mocks return values.
-    RemoteCommandTargeterMock::get(shardRegistry()->getShard(s0.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        shardRegistry()->getShard(operationContext(), s0.getName())->getTargeter())
         ->setFindHostReturnValue(HostAndPort(s0.getHost()));
-    RemoteCommandTargeterMock::get(shardRegistry()->getShard(s1.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        shardRegistry()->getShard(operationContext(), s1.getName())->getTargeter())
         ->setFindHostReturnValue(HostAndPort(s1.getHost()));
-    RemoteCommandTargeterMock::get(shardRegistry()->getShard(s2.getName())->getTargeter())
+    RemoteCommandTargeterMock::get(
+        shardRegistry()->getShard(operationContext(), s2.getName())->getTargeter())
         ->setFindHostReturnValue(HostAndPort(s2.getHost()));
 
 
@@ -1917,8 +1923,8 @@ TEST_F(CatalogManagerReplSetTest, EnableShardingNoDBExists) {
 
     setupShards(vector<ShardType>{shard});
 
-    RemoteCommandTargeterMock* shardTargeter =
-        RemoteCommandTargeterMock::get(shardRegistry()->getShard("shard0")->getTargeter());
+    RemoteCommandTargeterMock* shardTargeter = RemoteCommandTargeterMock::get(
+        shardRegistry()->getShard(operationContext(), "shard0")->getTargeter());
     shardTargeter->setFindHostReturnValue(HostAndPort("shard0:12"));
 
     distLock()->expectLock(
diff --git a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.cpp b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.cpp
index 4abfa250466..961ae5db7c2 100644
--- a/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.cpp
+++ b/src/mongo/s/catalog/replset/catalog_manager_replica_set_test_fixture.cpp
@@ -197,7 +197,7 @@ void CatalogManagerReplSetTestFixture::onFindWithMetadataCommand(
 }
 
 void CatalogManagerReplSetTestFixture::setupShards(const std::vector<ShardType>& shards) {
-    auto future = launchAsync([this] { shardRegistry()->reload(); });
+    auto future = launchAsync([this] { shardRegistry()->reload(operationContext()); });
 
     expectGetShards(shards);
 
diff --git a/src/mongo/s/chunk.cpp b/src/mongo/s/chunk.cpp
index ffe7f865650..8fba2d03de9 100644
--- a/src/mongo/s/chunk.cpp
+++ b/src/mongo/s/chunk.cpp
@@ -127,7 +127,7 @@ bool tryMoveToOtherShard(OperationContext* txn,
 
     log() << "moving chunk (auto): " << toMove->toString() << " to: " << newLocation;
 
-    shared_ptr<Shard> newShard = grid.shardRegistry()->getShard(newLocation);
+    shared_ptr<Shard> newShard = grid.shardRegistry()->getShard(txn, newLocation);
     if (!newShard) {
         warning() << "Newly selected shard " << newLocation << " could not be found.";
         return false;
@@ -159,29 +159,24 @@ int Chunk::MaxObjectPerChunk = 250000;
 // Can be overridden from command line
 bool Chunk::ShouldAutoSplit = true;
 
-Chunk::Chunk(const ChunkManager* manager, BSONObj from)
+Chunk::Chunk(OperationContext* txn, const ChunkManager* manager, ChunkType from)
     : _manager(manager), _lastmod(0, 0, OID()), _dataWritten(mkDataWritten()) {
-    string ns = from.getStringField(ChunkType::ns().c_str());
-    _shardId = from.getStringField(ChunkType::shard().c_str());
+    string ns = from.getNS();
+    _shardId = from.getShard();
 
-    _lastmod = ChunkVersion::fromBSON(from[ChunkType::DEPRECATED_lastmod()]);
+    _lastmod = from.getVersion();
     verify(_lastmod.isSet());
 
-    _min = from.getObjectField(ChunkType::min().c_str()).getOwned();
-    _max = from.getObjectField(ChunkType::max().c_str()).getOwned();
+    _min = from.getMin().getOwned();
+    _max = from.getMax().getOwned();
 
-    _jumbo = from[ChunkType::jumbo()].trueValue();
+    _jumbo = from.getJumbo();
 
     uassert(10170, "Chunk needs a ns", !ns.empty());
     uassert(13327, "Chunk ns must match server ns", ns == _manager->getns());
-
-    {
-        const auto shard = grid.shardRegistry()->getShard(_shardId);
-        uassert(10171, "Chunk needs a server", shard);
-    }
-
     uassert(10172, "Chunk needs a min", !_min.isEmpty());
     uassert(10173, "Chunk needs a max", !_max.isEmpty());
+    uassert(10171, "Chunk needs a server", grid.shardRegistry()->getShard(txn, _shardId));
 }
 
 Chunk::Chunk(const ChunkManager* info,
@@ -219,7 +214,7 @@ bool Chunk::_maxIsInf() const {
     return 0 == _manager->getShardKeyPattern().getKeyPattern().globalMax().woCompare(getMax());
 }
 
-BSONObj Chunk::_getExtremeKey(bool doSplitAtLower) const {
+BSONObj Chunk::_getExtremeKey(OperationContext* txn, bool doSplitAtLower) const {
     Query q;
     if (doSplitAtLower) {
         q.sort(_manager->getShardKeyPattern().toBSON());
@@ -241,7 +236,7 @@ BSONObj Chunk::_getExtremeKey(bool doSplitAtLower) const {
     }
 
     // find the extreme key
-    ScopedDbConnection conn(_getShardConnectionString());
+    ScopedDbConnection conn(_getShardConnectionString(txn));
     BSONObj end;
 
     if (doSplitAtLower) {
@@ -271,9 +266,9 @@ BSONObj Chunk::_getExtremeKey(bool doSplitAtLower) const {
     return _manager->getShardKeyPattern().extractShardKeyFromDoc(end);
 }
 
-void Chunk::pickMedianKey(BSONObj& medianKey) const {
+void Chunk::pickMedianKey(OperationContext* txn, BSONObj& medianKey) const {
     // Ask the mongod holding this chunk to figure out the split points.
-    ScopedDbConnection conn(_getShardConnectionString());
+    ScopedDbConnection conn(_getShardConnectionString(txn));
     BSONObj result;
     BSONObjBuilder cmd;
     cmd.append("splitVector", _manager->getns());
@@ -298,7 +293,8 @@ void Chunk::pickMedianKey(BSONObj& medianKey) const {
     conn.done();
 }
 
-void Chunk::pickSplitVector(vector<BSONObj>& splitPoints,
+void Chunk::pickSplitVector(OperationContext* txn,
+                            vector<BSONObj>& splitPoints,
                             long long chunkSize /* bytes */,
                             int maxPoints,
                             int maxObjs) const {
@@ -312,7 +308,7 @@ void Chunk::pickSplitVector(vector<BSONObj>& splitPoints,
     cmd.append("maxChunkObjects", maxObjs);
     BSONObj cmdObj = cmd.obj();
 
-    const auto primaryShard = grid.shardRegistry()->getShard(getShardId());
+    const auto primaryShard = grid.shardRegistry()->getShard(txn, getShardId());
     auto targetStatus =
         primaryShard->getTargeter()->findHost({ReadPreference::PrimaryPreferred, TagSet{}});
     uassertStatusOK(targetStatus);
@@ -328,13 +324,15 @@ void Chunk::pickSplitVector(vector<BSONObj>& splitPoints,
     }
 }
 
-void Chunk::determineSplitPoints(bool atMedian, vector<BSONObj>* splitPoints) const {
+void Chunk::determineSplitPoints(OperationContext* txn,
+                                 bool atMedian,
+                                 vector<BSONObj>* splitPoints) const {
     // if splitting is not obligatory we may return early if there are not enough data
     // we cap the number of objects that would fall in the first half (before the split point)
     // the rationale is we'll find a split point without traversing all the data
     if (atMedian) {
         BSONObj medianKey;
-        pickMedianKey(medianKey);
+        pickMedianKey(txn, medianKey);
         if (!medianKey.isEmpty())
             splitPoints->push_back(medianKey);
     } else {
@@ -350,7 +348,7 @@ void Chunk::determineSplitPoints(bool atMedian, vector<BSONObj>* splitPoints) co
             chunkSize = std::min(_dataWritten, Chunk::MaxChunkSize);
         }
 
-        pickSplitVector(*splitPoints, chunkSize, 0, MaxObjectPerChunk);
+        pickSplitVector(txn, *splitPoints, chunkSize, 0, MaxObjectPerChunk);
 
         if (splitPoints->size() <= 1) {
             // no split points means there isn't enough data to split on
@@ -373,7 +371,7 @@ Status Chunk::split(OperationContext* txn,
     bool atMedian = mode == Chunk::atMedian;
     vector<BSONObj> splitPoints;
 
-    determineSplitPoints(atMedian, &splitPoints);
+    determineSplitPoints(txn, atMedian, &splitPoints);
     if (splitPoints.empty()) {
         string msg;
         if (atMedian) {
@@ -394,12 +392,12 @@ Status Chunk::split(OperationContext* txn,
     if (mode == Chunk::autoSplitInternal &&
         KeyPattern::isOrderedKeyPattern(_manager->getShardKeyPattern().toBSON())) {
         if (_minIsInf()) {
-            BSONObj key = _getExtremeKey(true);
+            BSONObj key = _getExtremeKey(txn, true);
             if (!key.isEmpty()) {
                 splitPoints[0] = key.getOwned();
             }
         } else if (_maxIsInf()) {
-            BSONObj key = _getExtremeKey(false);
+            BSONObj key = _getExtremeKey(txn, false);
             if (!key.isEmpty()) {
                 splitPoints.pop_back();
                 splitPoints.push_back(key);
@@ -436,7 +434,7 @@ Status Chunk::multiSplit(OperationContext* txn, const vector<BSONObj>& m, BSONOb
     uassert(13333, "can't split a chunk in that many parts", m.size() < maxSplitPoints);
     uassert(13003, "can't split a chunk with only one distinct value", _min.woCompare(_max));
 
-    ScopedDbConnection conn(_getShardConnectionString());
+    ScopedDbConnection conn(_getShardConnectionString(txn));
 
     BSONObjBuilder cmd;
     cmd.append("splitChunk", _manager->getns());
@@ -482,13 +480,13 @@ bool Chunk::moveAndCommit(OperationContext* txn,
     log() << "moving chunk ns: " << _manager->getns() << " moving ( " << toString() << ") "
           << getShardId() << " -> " << toShardId;
 
-    const auto from = grid.shardRegistry()->getShard(getShardId());
+    const auto from = grid.shardRegistry()->getShard(txn, getShardId());
 
     BSONObjBuilder builder;
     builder.append("moveChunk", _manager->getns());
     builder.append("from", from->getConnString().toString());
     {
-        const auto toShard = grid.shardRegistry()->getShard(toShardId);
+        const auto toShard = grid.shardRegistry()->getShard(txn, toShardId);
         builder.append("to", toShard->getConnString().toString());
     }
     // NEEDED FOR 2.0 COMPATIBILITY
@@ -605,7 +603,7 @@ bool Chunk::splitIfShould(OperationContext* txn, long dataWritten) const {
 
             ChunkType chunkToMove;
             {
-                const auto shard = grid.shardRegistry()->getShard(getShardId());
+                const auto shard = grid.shardRegistry()->getShard(txn, getShardId());
                 chunkToMove.setShard(shard->toString());
             }
             chunkToMove.setMin(range["min"].embeddedObject());
@@ -627,28 +625,11 @@ bool Chunk::splitIfShould(OperationContext* txn, long dataWritten) const {
     }
 }
 
-std::string Chunk::_getShardConnectionString() const {
-    const auto shard = grid.shardRegistry()->getShard(getShardId());
+std::string Chunk::_getShardConnectionString(OperationContext* txn) const {
+    const auto shard = grid.shardRegistry()->getShard(txn, getShardId());
     return shard->getConnString().toString();
 }
 
-long Chunk::getPhysicalSize() const {
-    ScopedDbConnection conn(_getShardConnectionString());
-
-    BSONObj result;
-    uassert(10169,
-            "datasize failed!",
-            conn->runCommand("admin",
-                             BSON("datasize" << _manager->getns() << "keyPattern"
-                                             << _manager->getShardKeyPattern().toBSON() << "min"
-                                             << getMin() << "max" << getMax() << "maxSize"
-                                             << (MaxChunkSize + 1) << "estimate" << true),
-                             result));
-
-    conn.done();
-    return (long)result["size"].number();
-}
-
 void Chunk::appendShortVersion(const char* name, BSONObjBuilder& b) const {
     BSONObjBuilder bb(b.subobjStart(name));
     bb.append(ChunkType::min(), _min);
diff --git a/src/mongo/s/chunk.h b/src/mongo/s/chunk.h
index 1ec9a9447cb..ef4b619b342 100644
--- a/src/mongo/s/chunk.h
+++ b/src/mongo/s/chunk.h
@@ -28,6 +28,7 @@
 
 #pragma once
 
+#include "mongo/s/catalog/type_chunk.h"
 #include "mongo/s/chunk_version.h"
 #include "mongo/s/client/shard.h"
 
@@ -62,7 +63,7 @@ public:
         autoSplitInternal
     };
 
-    Chunk(const ChunkManager* info, BSONObj from);
+    Chunk(OperationContext* txn, const ChunkManager* info, ChunkType from);
     Chunk(const ChunkManager* info,
           const BSONObj& min,
           const BSONObj& max,
@@ -161,7 +162,7 @@ public:
      *
      * @param medianKey the key that divides this chunk, if there is one, or empty
      */
-    void pickMedianKey(BSONObj& medianKey) const;
+    void pickMedianKey(OperationContext* txn, BSONObj& medianKey) const;
 
     /**
      * Ask the mongod holding this chunk to figure out the split points.
@@ -170,7 +171,8 @@ public:
      * @param maxPoints limits the number of split points that are needed, zero is max (optional)
      * @param maxObjs limits the number of objects in each chunk, zero is as max (optional)
      */
-    void pickSplitVector(std::vector<BSONObj>& splitPoints,
+    void pickSplitVector(OperationContext* txn,
+                         std::vector<BSONObj>& splitPoints,
                          long long chunkSize,
                          int maxPoints = 0,
                          int maxObjs = 0) const;
@@ -199,12 +201,6 @@ public:
                        BSONObj& res) const;
 
     /**
-     * @return size of shard in bytes
-     *  talks to mongod to do this
-     */
-    long getPhysicalSize() const;
-
-    /**
      * marks this chunk as a jumbo chunk
      * that means the chunk will be inelligble for migrates
      */
@@ -261,7 +257,7 @@ private:
     /**
      * Returns the connection string for the shard on which this chunk resides.
      */
-    std::string _getShardConnectionString() const;
+    std::string _getShardConnectionString(OperationContext* txn) const;
 
     // if min/max key is pos/neg infinity
     bool _minIsInf() const;
@@ -293,7 +289,7 @@ private:
      *          is simply an ordered list of ascending/descending field names. Examples:
      *          {a : 1, b : -1} is not special. {a : "hashed"} is.
      */
-    BSONObj _getExtremeKey(bool doSplitAtLower) const;
+    BSONObj _getExtremeKey(OperationContext* txn, bool doSplitAtLower) const;
 
     /**
      * Determines the appropriate split points for this chunk.
@@ -301,7 +297,9 @@ private:
      * @param atMedian perform a single split at the middle of this chunk.
      * @param splitPoints out parameter containing the chosen split points. Can be empty.
      */
-    void determineSplitPoints(bool atMedian, std::vector<BSONObj>* splitPoints) const;
+    void determineSplitPoints(OperationContext* txn,
+                              bool atMedian,
+                              std::vector<BSONObj>* splitPoints) const;
 
     /**
      * initializes _dataWritten with a random value so that a mongos restart
diff --git a/src/mongo/s/chunk_diff.cpp b/src/mongo/s/chunk_diff.cpp
index e3b0f9fa2f0..8cdfaf52475 100644
--- a/src/mongo/s/chunk_diff.cpp
+++ b/src/mongo/s/chunk_diff.cpp
@@ -109,7 +109,8 @@ typename ConfigDiffTracker<ValType>::RangeOverlap ConfigDiffTracker<ValType>::ov
 }
 
 template <class ValType>
-int ConfigDiffTracker<ValType>::calculateConfigDiff(const std::vector<ChunkType>& chunks) {
+int ConfigDiffTracker<ValType>::calculateConfigDiff(OperationContext* txn,
+                                                    const std::vector<ChunkType>& chunks) {
     _assertAttached();
 
     // Apply the chunk changes to the ranges and versions
@@ -149,7 +150,7 @@ int ConfigDiffTracker<ValType>::calculateConfigDiff(const std::vector<ChunkType>
         }
 
         // Chunk version changes
-        ShardId shard = shardFor(chunk.getShard());
+        ShardId shard = shardFor(txn, chunk.getShard());
 
         typename MaxChunkVersionMap::const_iterator shardVersionIt = _maxShardVersions->find(shard);
         if (shardVersionIt == _maxShardVersions->end() || shardVersionIt->second < chunkVersion) {
@@ -181,7 +182,7 @@ int ConfigDiffTracker<ValType>::calculateConfigDiff(const std::vector<ChunkType>
             return -1;
         }
 
-        _currMap->insert(rangeFor(chunk));
+        _currMap->insert(rangeFor(txn, chunk));
     }
 
     return _validDiffs;
diff --git a/src/mongo/s/chunk_diff.h b/src/mongo/s/chunk_diff.h
index ce53a95a043..cf47c34eb41 100644
--- a/src/mongo/s/chunk_diff.h
+++ b/src/mongo/s/chunk_diff.h
@@ -38,6 +38,7 @@ namespace mongo {
 
 class ChunkType;
 struct ChunkVersion;
+class OperationContext;
 
 class ConfigDiffTrackerBase {
 public:
@@ -113,7 +114,7 @@ public:
     // Applies changes to the config data from a vector of chunks passed in. Also includes minor
     // version changes for particular major-version chunks if explicitly specified.
     // Returns the number of diffs processed, or -1 if the diffs were inconsistent.
-    int calculateConfigDiff(const std::vector<ChunkType>& chunks);
+    int calculateConfigDiff(OperationContext* txn, const std::vector<ChunkType>& chunks);
 
     // Returns the query needed to find new changes to a collection from the config server
     // Needed only if a custom connection is required to the config server
@@ -133,9 +134,10 @@ protected:
         return true;
     }
 
-    virtual std::pair<BSONObj, ValType> rangeFor(const ChunkType& chunk) const = 0;
+    virtual std::pair<BSONObj, ValType> rangeFor(OperationContext* txn,
+                                                 const ChunkType& chunk) const = 0;
 
-    virtual ShardId shardFor(const std::string& name) const = 0;
+    virtual ShardId shardFor(OperationContext* txn, const std::string& name) const = 0;
 
 private:
     void _assertAttached() const;
diff --git a/src/mongo/s/chunk_diff_test.cpp b/src/mongo/s/chunk_diff_test.cpp
index 76df3e999a6..28dd7e63f1e 100644
--- a/src/mongo/s/chunk_diff_test.cpp
+++ b/src/mongo/s/chunk_diff_test.cpp
@@ -33,6 +33,7 @@
 #include <utility>
 
 #include "mongo/db/jsobj.h"
+#include "mongo/db/operation_context_noop.h"
 #include "mongo/platform/random.h"
 #include "mongo/s/catalog/type_chunk.h"
 #include "mongo/s/chunk_diff.h"
@@ -61,11 +62,11 @@ public:
         return true;
     }
 
-    virtual pair<BSONObj, BSONObj> rangeFor(const ChunkType& chunk) const {
+    virtual pair<BSONObj, BSONObj> rangeFor(OperationContext* txn, const ChunkType& chunk) const {
         return make_pair(chunk.getMin(), chunk.getMax());
     }
 
-    virtual ShardId shardFor(const string& name) const {
+    virtual ShardId shardFor(OperationContext* txn, const string& name) const {
         return name;
     }
 };
@@ -82,7 +83,7 @@ public:
         return false;
     }
 
-    virtual pair<BSONObj, BSONObj> rangeFor(const ChunkType& chunk) const {
+    virtual pair<BSONObj, BSONObj> rangeFor(OperationContext* txn, const ChunkType& chunk) const {
         return make_pair(chunk.getMax(), chunk.getMin());
     }
 };
@@ -108,6 +109,7 @@ protected:
     ~ChunkDiffUnitTest() = default;
 
     void runTest(bool isInverse) {
+        OperationContextNoop txn;
         int numShards = 10;
         int numInitialChunks = 5;
 
@@ -173,7 +175,7 @@ protected:
         convertBSONArrayToChunkTypes(chunks, &chunksVector);
 
         // Validate initial load
-        differ->calculateConfigDiff(chunksVector);
+        differ->calculateConfigDiff(&txn, chunksVector);
         validate(isInverse, chunksVector, ranges, maxVersion, maxShardVersions);
 
         // Generate a lot of diffs, and keep validating that updating from the diffs always gives us
@@ -328,7 +330,7 @@ protected:
             std::vector<ChunkType> chunksVector;
             convertBSONArrayToChunkTypes(chunks, &chunksVector);
 
-            differ->calculateConfigDiff(chunksVector);
+            differ->calculateConfigDiff(&txn, chunksVector);
 
             validate(isInverse, chunksVector, ranges, maxVersion, maxShardVersions);
         }
diff --git a/src/mongo/s/chunk_manager.cpp b/src/mongo/s/chunk_manager.cpp
index e9465705e3a..8d01285dadc 100644
--- a/src/mongo/s/chunk_manager.cpp
+++ b/src/mongo/s/chunk_manager.cpp
@@ -89,13 +89,14 @@ public:
         return false;
     }
 
-    pair<BSONObj, shared_ptr<Chunk>> rangeFor(const ChunkType& chunk) const final {
-        shared_ptr<Chunk> c(new Chunk(_manager, chunk.toBSON()));
+    pair<BSONObj, shared_ptr<Chunk>> rangeFor(OperationContext* txn,
+                                              const ChunkType& chunk) const final {
+        shared_ptr<Chunk> c(new Chunk(txn, _manager, chunk));
         return make_pair(chunk.getMax(), c);
     }
 
-    string shardFor(const string& hostName) const final {
-        const auto shard = grid.shardRegistry()->getShard(hostName);
+    string shardFor(OperationContext* txn, const string& hostName) const final {
+        const auto shard = grid.shardRegistry()->getShard(txn, hostName);
         return shard->getId();
     }
 
@@ -269,14 +270,14 @@ bool ChunkManager::_load(OperationContext* txn,
     invariant(opTime >= _configOpTime);
     _configOpTime = opTime;
 
-    int diffsApplied = differ.calculateConfigDiff(chunks);
+    int diffsApplied = differ.calculateConfigDiff(txn, chunks);
     if (diffsApplied > 0) {
         LOG(2) << "loaded " << diffsApplied << " chunks into new chunk manager for " << _ns
                << " with version " << _version;
 
         // Add all existing shards we find to the shards set
         for (ShardVersionMap::iterator it = shardVersions->begin(); it != shardVersions->end();) {
-            shared_ptr<Shard> shard = grid.shardRegistry()->getShard(it->first);
+            shared_ptr<Shard> shard = grid.shardRegistry()->getShard(txn, it->first);
             if (shard) {
                 shardIds.insert(it->first);
                 ++it;
@@ -339,7 +340,8 @@ void ChunkManager::_printChunks() const {
     }
 }
 
-void ChunkManager::calcInitSplitsAndShards(const ShardId& primaryShardId,
+void ChunkManager::calcInitSplitsAndShards(OperationContext* txn,
+                                           const ShardId& primaryShardId,
                                            const vector<BSONObj>* initPoints,
                                            const set<ShardId>* initShardIds,
                                            vector<BSONObj>* splitPoints,
@@ -353,7 +355,7 @@ void ChunkManager::calcInitSplitsAndShards(const ShardId& primaryShardId,
 
     if (!initPoints || !initPoints->size()) {
         // discover split points
-        const auto primaryShard = grid.shardRegistry()->getShard(primaryShardId);
+        const auto primaryShard = grid.shardRegistry()->getShard(txn, primaryShardId);
         auto targetStatus =
             primaryShard->getTargeter()->findHost({ReadPreference::PrimaryPreferred, TagSet{}});
         uassertStatusOK(targetStatus);
@@ -368,7 +370,7 @@ void ChunkManager::calcInitSplitsAndShards(const ShardId& primaryShardId,
         uassertStatusOK(bsonExtractIntegerField(result.getValue(), "n", &numObjects));
 
         if (numObjects > 0)
-            c.pickSplitVector(*splitPoints, Chunk::MaxChunkSize);
+            c.pickSplitVector(txn, *splitPoints, Chunk::MaxChunkSize);
 
         // since docs already exists, must use primary shard
         shardIds->push_back(primaryShardId);
@@ -403,7 +405,7 @@ void ChunkManager::createFirstChunks(OperationContext* txn,
 
     vector<BSONObj> splitPoints;
     vector<ShardId> shardIds;
-    calcInitSplitsAndShards(primaryShardId, initPoints, initShardIds, &splitPoints, &shardIds);
+    calcInitSplitsAndShards(txn, primaryShardId, initPoints, initShardIds, &splitPoints, &shardIds);
 
 
     // this is the first chunk; start the versioning from scratch
diff --git a/src/mongo/s/chunk_manager.h b/src/mongo/s/chunk_manager.h
index c640bf26ed9..a87d70f2fed 100644
--- a/src/mongo/s/chunk_manager.h
+++ b/src/mongo/s/chunk_manager.h
@@ -171,7 +171,8 @@ public:
 
 
     // Helpers for load
-    void calcInitSplitsAndShards(const ShardId& primaryShardId,
+    void calcInitSplitsAndShards(OperationContext* txn,
+                                 const ShardId& primaryShardId,
                                  const std::vector<BSONObj>* initPoints,
                                  const std::set<ShardId>* initShardIds,
                                  std::vector<BSONObj>* splitPoints,
diff --git a/src/mongo/s/chunk_manager_targeter.cpp b/src/mongo/s/chunk_manager_targeter.cpp
index a3de1e2235e..320ba5a4fb8 100644
--- a/src/mongo/s/chunk_manager_targeter.cpp
+++ b/src/mongo/s/chunk_manager_targeter.cpp
@@ -273,7 +273,7 @@ Status ChunkManagerTargeter::init(OperationContext* txn) {
     }
 
     shared_ptr<DBConfig> config = status.getValue();
-    config->getChunkManagerOrPrimary(_nss.ns(), _manager, _primary);
+    config->getChunkManagerOrPrimary(txn, _nss.ns(), _manager, _primary);
 
     return Status::OK();
 }
@@ -642,7 +642,7 @@ Status ChunkManagerTargeter::refreshIfNeeded(OperationContext* txn, bool* wasCha
     }
 
     shared_ptr<DBConfig> config = status.getValue();
-    config->getChunkManagerOrPrimary(_nss.ns(), _manager, _primary);
+    config->getChunkManagerOrPrimary(txn, _nss.ns(), _manager, _primary);
 
     // We now have the latest metadata from the cache.
 
@@ -716,7 +716,7 @@ Status ChunkManagerTargeter::refreshNow(OperationContext* txn, RefreshType refre
         } catch (const DBException& ex) {
             return Status(ErrorCodes::UnknownError, ex.toString());
         }
-        config->getChunkManagerOrPrimary(_nss.ns(), _manager, _primary);
+        config->getChunkManagerOrPrimary(txn, _nss.ns(), _manager, _primary);
     } else if (refreshType == RefreshType_ReloadDatabase) {
         try {
             // Dumps the db info, reloads it all, synchronization between threads happens
@@ -727,7 +727,7 @@ Status ChunkManagerTargeter::refreshNow(OperationContext* txn, RefreshType refre
             return Status(ErrorCodes::UnknownError, ex.toString());
         }
 
-        config->getChunkManagerOrPrimary(_nss.ns(), _manager, _primary);
+        config->getChunkManagerOrPrimary(txn, _nss.ns(), _manager, _primary);
     }
 
     return Status::OK();
diff --git a/src/mongo/s/client/shard_connection.cpp b/src/mongo/s/client/shard_connection.cpp
index 3850e6d747f..9be2f45a028 100644
--- a/src/mongo/s/client/shard_connection.cpp
+++ b/src/mongo/s/client/shard_connection.cpp
@@ -288,7 +288,7 @@ public:
         // Now only check top-level shard connections
         for (const ShardId& shardId : all) {
             try {
-                const auto shard = grid.shardRegistry()->getShard(shardId);
+                const auto shard = grid.shardRegistry()->getShard(txn, shardId);
                 if (!shard) {
                     continue;
                 }
diff --git a/src/mongo/s/client/shard_registry.cpp b/src/mongo/s/client/shard_registry.cpp
index 0397d44d8c9..69c2c6448e6 100644
--- a/src/mongo/s/client/shard_registry.cpp
+++ b/src/mongo/s/client/shard_registry.cpp
@@ -94,9 +94,9 @@ void ShardRegistry::shutdown() {
     _executor->join();
 }
 
-void ShardRegistry::reload() {
+void ShardRegistry::reload(OperationContext* txn) {
     vector<ShardType> shards;
-    Status status = grid.catalogManager()->getAllShards(&shards);
+    Status status = grid.catalogManager()->getAllShards(txn, &shards);
     uassert(13632,
             str::stream() << "could not get updated shard list from config server due to "
                           << status.toString(),
@@ -126,18 +126,24 @@ void ShardRegistry::reload() {
     }
 }
 
-shared_ptr<Shard> ShardRegistry::getShard(const ShardId& shardId) {
+shared_ptr<Shard> ShardRegistry::getShard(OperationContext* txn, const ShardId& shardId) {
     shared_ptr<Shard> shard = _findUsingLookUp(shardId);
     if (shard) {
         return shard;
     }
 
     // If we can't find the shard, we might just need to reload the cache
-    reload();
+    reload(txn);
 
     return _findUsingLookUp(shardId);
 }
 
+shared_ptr<Shard> ShardRegistry::getConfigShard() {
+    shared_ptr<Shard> shard = _findUsingLookUp("config");
+    invariant(shard);
+    return shard;
+}
+
 unique_ptr<Shard> ShardRegistry::createConnection(const ConnectionString& connStr) const {
     return stdx::make_unique<Shard>("<unnamed>", connStr, _targeterFactory->create(connStr));
 }
@@ -404,10 +410,29 @@ StatusWith<ShardRegistry::CommandResponse> ShardRegistry::runCommandWithMetadata
     return cmdResponse;
 }
 
-StatusWith<BSONObj> ShardRegistry::runCommandWithNotMasterRetries(const ShardId& shardId,
+StatusWith<BSONObj> ShardRegistry::runCommandOnConfigWithNotMasterRetries(const std::string& dbname,
+                                                                          const BSONObj& cmdObj) {
+    auto status = runCommandOnConfigWithNotMasterRetries(dbname, cmdObj, rpc::makeEmptyMetadata());
+
+    if (!status.isOK()) {
+        return status.getStatus();
+    }
+
+    return status.getValue().response;
+}
+
+StatusWith<ShardRegistry::CommandResponse> ShardRegistry::runCommandOnConfigWithNotMasterRetries(
+    const std::string& dbname, const BSONObj& cmdObj, const BSONObj& metadata) {
+    auto configShard = getConfigShard();
+    return _runCommandWithNotMasterRetries(configShard->getTargeter(), dbname, cmdObj, metadata);
+}
+
+StatusWith<BSONObj> ShardRegistry::runCommandWithNotMasterRetries(OperationContext* txn,
+                                                                  const ShardId& shardId,
                                                                   const std::string& dbname,
                                                                   const BSONObj& cmdObj) {
-    auto status = runCommandWithNotMasterRetries(shardId, dbname, cmdObj, rpc::makeEmptyMetadata());
+    auto status =
+        runCommandWithNotMasterRetries(txn, shardId, dbname, cmdObj, rpc::makeEmptyMetadata());
 
     if (!status.isOK()) {
         return status.getStatus();
@@ -417,11 +442,20 @@ StatusWith<BSONObj> ShardRegistry::runCommandWithNotMasterRetries(const ShardId&
 }
 
 StatusWith<ShardRegistry::CommandResponse> ShardRegistry::runCommandWithNotMasterRetries(
+    OperationContext* txn,
     const ShardId& shardId,
     const std::string& dbname,
     const BSONObj& cmdObj,
     const BSONObj& metadata) {
-    auto targeter = getShard(shardId)->getTargeter();
+    auto shard = getShard(txn, shardId);
+    return _runCommandWithNotMasterRetries(shard->getTargeter(), dbname, cmdObj, metadata);
+}
+
+StatusWith<ShardRegistry::CommandResponse> ShardRegistry::_runCommandWithNotMasterRetries(
+    RemoteCommandTargeter* targeter,
+    const std::string& dbname,
+    const BSONObj& cmdObj,
+    const BSONObj& metadata) {
     const ReadPreferenceSetting readPref(ReadPreference::PrimaryOnly, TagSet{});
 
     for (int i = 0; i < kNotMasterNumRetries; ++i) {
diff --git a/src/mongo/s/client/shard_registry.h b/src/mongo/s/client/shard_registry.h
index 5f1349de7f8..38cdae15cbc 100644
--- a/src/mongo/s/client/shard_registry.h
+++ b/src/mongo/s/client/shard_registry.h
@@ -46,6 +46,7 @@ class BSONObjBuilder;
 class CatalogManager;
 struct HostAndPort;
 class NamespaceString;
+class OperationContext;
 class RemoteCommandTargeterFactory;
 class Shard;
 class ShardType;
@@ -123,12 +124,17 @@ public:
         return _configServerCS;
     }
 
-    void reload();
+    void reload(OperationContext* txn);
 
     /**
      * Returns shared pointer to shard object with given shard id.
      */
-    std::shared_ptr<Shard> getShard(const ShardId& shardId);
+    std::shared_ptr<Shard> getShard(OperationContext* txn, const ShardId& shardId);
+
+    /**
+     * Returns shared pointer to the shard object representing the config servers.
+     */
+    std::shared_ptr<Shard> getConfigShard();
 
     /**
      * Instantiates a new detached shard connection, which does not appear in the list of shards
@@ -196,15 +202,24 @@ public:
      * response object for any kind of command-specific failure.  The only exception is
      * NotMaster errors, which we intercept and follow the rules described above for handling.
      */
-    StatusWith<BSONObj> runCommandWithNotMasterRetries(const ShardId& shard,
+    StatusWith<BSONObj> runCommandWithNotMasterRetries(OperationContext* txn,
+                                                       const ShardId& shard,
                                                        const std::string& dbname,
                                                        const BSONObj& cmdObj);
 
-    StatusWith<CommandResponse> runCommandWithNotMasterRetries(const ShardId& shardId,
+    StatusWith<CommandResponse> runCommandWithNotMasterRetries(OperationContext* txn,
+                                                               const ShardId& shardId,
                                                                const std::string& dbname,
                                                                const BSONObj& cmdObj,
                                                                const BSONObj& metadata);
 
+    StatusWith<BSONObj> runCommandOnConfigWithNotMasterRetries(const std::string& dbname,
+                                                               const BSONObj& cmdObj);
+
+    StatusWith<CommandResponse> runCommandOnConfigWithNotMasterRetries(const std::string& dbname,
+                                                                       const BSONObj& cmdObj,
+                                                                       const BSONObj& metadata);
+
 private:
     typedef std::map<ShardId, std::shared_ptr<Shard>> ShardMap;
 
@@ -220,6 +235,11 @@ private:
 
     std::shared_ptr<Shard> _findUsingLookUp(const ShardId& shardId);
 
+    StatusWith<CommandResponse> _runCommandWithNotMasterRetries(RemoteCommandTargeter* targeter,
+                                                                const std::string& dbname,
+                                                                const BSONObj& cmdObj,
+                                                                const BSONObj& metadata);
+
     // Factory to obtain remote command targeters for shards
     const std::unique_ptr<RemoteCommandTargeterFactory> _targeterFactory;
 
diff --git a/src/mongo/s/cluster_explain.cpp b/src/mongo/s/cluster_explain.cpp
index 6f6ae2cb95e..cb6143e6231 100644
--- a/src/mongo/s/cluster_explain.cpp
+++ b/src/mongo/s/cluster_explain.cpp
@@ -191,7 +191,8 @@ const char* ClusterExplain::getStageNameForReadOp(
 }
 
 // static
-void ClusterExplain::buildPlannerInfo(const vector<Strategy::CommandResult>& shardResults,
+void ClusterExplain::buildPlannerInfo(OperationContext* txn,
+                                      const vector<Strategy::CommandResult>& shardResults,
                                       const char* mongosStageName,
                                       BSONObjBuilder* out) {
     BSONObjBuilder queryPlannerBob(out->subobjStart("queryPlanner"));
@@ -209,7 +210,7 @@ void ClusterExplain::buildPlannerInfo(const vector<Strategy::CommandResult>& sha
 
         singleShardBob.append("shardName", shardResults[i].shardTargetId);
         {
-            const auto shard = grid.shardRegistry()->getShard(shardResults[i].shardTargetId);
+            const auto shard = grid.shardRegistry()->getShard(txn, shardResults[i].shardTargetId);
             singleShardBob.append("connectionString", shard->getConnString().toString());
         }
         appendIfRoom(&singleShardBob, serverInfo, "serverInfo");
@@ -331,7 +332,8 @@ void ClusterExplain::buildExecStats(const vector<Strategy::CommandResult>& shard
 }
 
 // static
-Status ClusterExplain::buildExplainResult(const vector<Strategy::CommandResult>& shardResults,
+Status ClusterExplain::buildExplainResult(OperationContext* txn,
+                                          const vector<Strategy::CommandResult>& shardResults,
                                           const char* mongosStageName,
                                           long long millisElapsed,
                                           BSONObjBuilder* out) {
@@ -341,7 +343,7 @@ Status ClusterExplain::buildExplainResult(const vector<Strategy::CommandResult>&
         return validateStatus;
     }
 
-    buildPlannerInfo(shardResults, mongosStageName, out);
+    buildPlannerInfo(txn, shardResults, mongosStageName, out);
     buildExecStats(shardResults, mongosStageName, millisElapsed, out);
 
     return Status::OK();
diff --git a/src/mongo/s/cluster_explain.h b/src/mongo/s/cluster_explain.h
index dad3b25c5e7..6023a1db4f7 100644
--- a/src/mongo/s/cluster_explain.h
+++ b/src/mongo/s/cluster_explain.h
@@ -36,6 +36,8 @@
 
 namespace mongo {
 
+class OperationContext;
+
 /**
  * Namespace for the collection of static methods used by commands in the implementation of
  * explain on mongos.
@@ -67,7 +69,8 @@ public:
      *
      * On success, the output is added to the BSONObj builder 'out'.
      */
-    static Status buildExplainResult(const std::vector<Strategy::CommandResult>& shardResults,
+    static Status buildExplainResult(OperationContext* txn,
+                                     const std::vector<Strategy::CommandResult>& shardResults,
                                      const char* mongosStageName,
                                      long long millisElapsed,
                                      BSONObjBuilder* out);
@@ -95,7 +98,8 @@ private:
      * The planner info will display 'mongosStageName' as the name of the execution stage
      * performed by mongos after gathering results from the shards.
      */
-    static void buildPlannerInfo(const std::vector<Strategy::CommandResult>& shardResults,
+    static void buildPlannerInfo(OperationContext* txn,
+                                 const std::vector<Strategy::CommandResult>& shardResults,
                                  const char* mongosStageName,
                                  BSONObjBuilder* out);
 
diff --git a/src/mongo/s/cluster_write.cpp b/src/mongo/s/cluster_write.cpp
index 4660e8dbabd..5bc28be8fb3 100644
--- a/src/mongo/s/cluster_write.cpp
+++ b/src/mongo/s/cluster_write.cpp
@@ -127,7 +127,7 @@ void splitIfNeeded(OperationContext* txn, const NamespaceString& nss, const Targ
 
     ChunkManagerPtr chunkManager;
     shared_ptr<Shard> dummyShard;
-    config->getChunkManagerOrPrimary(nss.ns(), chunkManager, dummyShard);
+    config->getChunkManagerOrPrimary(txn, nss.ns(), chunkManager, dummyShard);
 
     if (!chunkManager) {
         return;
diff --git a/src/mongo/s/commands/cluster_count_cmd.cpp b/src/mongo/s/commands/cluster_count_cmd.cpp
index 3253afc6ba2..4c3146d9659 100644
--- a/src/mongo/s/commands/cluster_count_cmd.cpp
+++ b/src/mongo/s/commands/cluster_count_cmd.cpp
@@ -221,7 +221,7 @@ public:
         const char* mongosStageName = ClusterExplain::getStageNameForReadOp(shardResults, cmdObj);
 
         return ClusterExplain::buildExplainResult(
-            shardResults, mongosStageName, millisElapsed, out);
+            txn, shardResults, mongosStageName, millisElapsed, out);
     }
 
 } clusterCountCmd;
diff --git a/src/mongo/s/commands/cluster_find_and_modify_cmd.cpp b/src/mongo/s/commands/cluster_find_and_modify_cmd.cpp
index fe9ab7787d5..120af9b345b 100644
--- a/src/mongo/s/commands/cluster_find_and_modify_cmd.cpp
+++ b/src/mongo/s/commands/cluster_find_and_modify_cmd.cpp
@@ -90,7 +90,7 @@ public:
         shared_ptr<Shard> shard;
 
         if (!conf->isShardingEnabled() || !conf->isSharded(ns)) {
-            shard = grid.shardRegistry()->getShard(conf->getPrimaryId());
+            shard = grid.shardRegistry()->getShard(txn, conf->getPrimaryId());
         } else {
             shared_ptr<ChunkManager> chunkMgr = _getChunkManager(txn, conf, ns);
 
@@ -104,7 +104,7 @@ public:
             BSONObj shardKey = status.getValue();
             ChunkPtr chunk = chunkMgr->findIntersectingChunk(txn, shardKey);
 
-            shard = grid.shardRegistry()->getShard(chunk->getShardId());
+            shard = grid.shardRegistry()->getShard(txn, chunk->getShardId());
         }
 
         BSONObjBuilder explainCmd;
@@ -114,7 +114,7 @@ public:
         Timer timer;
 
         BSONObjBuilder result;
-        bool ok = _runCommand(conf, shard->getId(), ns, explainCmd.obj(), result);
+        bool ok = _runCommand(txn, conf, shard->getId(), ns, explainCmd.obj(), result);
         long long millisElapsed = timer.millis();
 
         if (!ok) {
@@ -132,7 +132,7 @@ public:
         shardResults.push_back(cmdResult);
 
         return ClusterExplain::buildExplainResult(
-            shardResults, ClusterExplain::kSingleShard, millisElapsed, out);
+            txn, shardResults, ClusterExplain::kSingleShard, millisElapsed, out);
     }
 
     virtual bool run(OperationContext* txn,
@@ -147,7 +147,7 @@ public:
         // require that the parsing be pulled into this function.
         auto conf = uassertStatusOK(grid.implicitCreateDb(txn, dbName));
         if (!conf->isShardingEnabled() || !conf->isSharded(ns)) {
-            return _runCommand(conf, conf->getPrimaryId(), ns, cmdObj, result);
+            return _runCommand(txn, conf, conf->getPrimaryId(), ns, cmdObj, result);
         }
 
         shared_ptr<ChunkManager> chunkMgr = _getChunkManager(txn, conf, ns);
@@ -163,7 +163,7 @@ public:
         BSONObj shardKey = status.getValue();
         ChunkPtr chunk = chunkMgr->findIntersectingChunk(txn, shardKey);
 
-        bool ok = _runCommand(conf, chunk->getShardId(), ns, cmdObj, result);
+        bool ok = _runCommand(txn, conf, chunk->getShardId(), ns, cmdObj, result);
         if (ok) {
             // check whether split is necessary (using update object for size heuristic)
             if (Chunk::ShouldAutoSplit) {
@@ -203,14 +203,15 @@ private:
         return shardKey;
     }
 
-    bool _runCommand(shared_ptr<DBConfig> conf,
+    bool _runCommand(OperationContext* txn,
+                     shared_ptr<DBConfig> conf,
                      const ShardId& shardId,
                      const string& ns,
                      const BSONObj& cmdObj,
                      BSONObjBuilder& result) const {
         BSONObj res;
 
-        const auto shard = grid.shardRegistry()->getShard(shardId);
+        const auto shard = grid.shardRegistry()->getShard(txn, shardId);
         ShardConnection conn(shard->getConnString(), ns);
         bool ok = conn->runCommand(conf->name(), cmdObj, res);
         conn.done();
diff --git a/src/mongo/s/commands/cluster_find_cmd.cpp b/src/mongo/s/commands/cluster_find_cmd.cpp
index 6a884e372e3..e38bca1334b 100644
--- a/src/mongo/s/commands/cluster_find_cmd.cpp
+++ b/src/mongo/s/commands/cluster_find_cmd.cpp
@@ -143,7 +143,7 @@ public:
         const char* mongosStageName = ClusterExplain::getStageNameForReadOp(shardResults, cmdObj);
 
         return ClusterExplain::buildExplainResult(
-            shardResults, mongosStageName, millisElapsed, out);
+            txn, shardResults, mongosStageName, millisElapsed, out);
     }
 
     bool run(OperationContext* txn,
diff --git a/src/mongo/s/commands/cluster_fsync_cmd.cpp b/src/mongo/s/commands/cluster_fsync_cmd.cpp
index 90735a25784..34098d450d6 100644
--- a/src/mongo/s/commands/cluster_fsync_cmd.cpp
+++ b/src/mongo/s/commands/cluster_fsync_cmd.cpp
@@ -86,7 +86,7 @@ public:
         grid.shardRegistry()->getAllShardIds(&shardIds);
 
         for (const ShardId& shardId : shardIds) {
-            const auto s = grid.shardRegistry()->getShard(shardId);
+            const auto s = grid.shardRegistry()->getShard(txn, shardId);
             if (!s) {
                 continue;
             }
diff --git a/src/mongo/s/commands/cluster_kill_op.cpp b/src/mongo/s/commands/cluster_kill_op.cpp
index 056f4b7ff60..d99abb461f0 100644
--- a/src/mongo/s/commands/cluster_kill_op.cpp
+++ b/src/mongo/s/commands/cluster_kill_op.cpp
@@ -99,7 +99,7 @@ public:
         log() << "want to kill op: " << opToKill;
 
         // Will throw if shard id is not found
-        auto shard = grid.shardRegistry()->getShard(shardIdent);
+        auto shard = grid.shardRegistry()->getShard(txn, shardIdent);
         if (!shard) {
             return appendCommandStatus(
                 result,
diff --git a/src/mongo/s/commands/cluster_list_databases_cmd.cpp b/src/mongo/s/commands/cluster_list_databases_cmd.cpp
index 0878123bc39..fc2ea7b22f0 100644
--- a/src/mongo/s/commands/cluster_list_databases_cmd.cpp
+++ b/src/mongo/s/commands/cluster_list_databases_cmd.cpp
@@ -94,7 +94,7 @@ public:
         grid.shardRegistry()->getAllShardIds(&shardIds);
 
         for (const ShardId& shardId : shardIds) {
-            const auto s = grid.shardRegistry()->getShard(shardId);
+            const auto s = grid.shardRegistry()->getShard(txn, shardId);
             if (!s) {
                 continue;
             }
diff --git a/src/mongo/s/commands/cluster_list_shards_cmd.cpp b/src/mongo/s/commands/cluster_list_shards_cmd.cpp
index da852b42ee7..dedbc136726 100644
--- a/src/mongo/s/commands/cluster_list_shards_cmd.cpp
+++ b/src/mongo/s/commands/cluster_list_shards_cmd.cpp
@@ -74,7 +74,7 @@ public:
                      std::string& errmsg,
                      BSONObjBuilder& result) {
         std::vector<ShardType> shards;
-        Status status = grid.catalogManager(txn)->getAllShards(&shards);
+        Status status = grid.catalogManager(txn)->getAllShards(txn, &shards);
         if (!status.isOK()) {
             return appendCommandStatus(result, status);
         }
diff --git a/src/mongo/s/commands/cluster_map_reduce_cmd.cpp b/src/mongo/s/commands/cluster_map_reduce_cmd.cpp
index 728ebc76bd7..3c942c5e89e 100644
--- a/src/mongo/s/commands/cluster_map_reduce_cmd.cpp
+++ b/src/mongo/s/commands/cluster_map_reduce_cmd.cpp
@@ -266,7 +266,7 @@ public:
         if (!shardedInput && !shardedOutput && !customOutDB) {
             LOG(1) << "simple MR, just passthrough";
 
-            const auto shard = grid.shardRegistry()->getShard(confIn->getPrimaryId());
+            const auto shard = grid.shardRegistry()->getShard(txn, confIn->getPrimaryId());
             ShardConnection conn(shard->getConnString(), "");
 
             BSONObj res;
@@ -312,7 +312,7 @@ public:
                 // Need to gather list of all servers even if an error happened
                 string server;
                 {
-                    const auto shard = grid.shardRegistry()->getShard(mrResult.shardTargetId);
+                    const auto shard = grid.shardRegistry()->getShard(txn, mrResult.shardTargetId);
                     server = shard->getConnString().toString();
                 }
                 servers.insert(server);
@@ -403,7 +403,7 @@ public:
         BSONObj singleResult;
 
         if (!shardedOutput) {
-            const auto shard = grid.shardRegistry()->getShard(confOut->getPrimaryId());
+            const auto shard = grid.shardRegistry()->getShard(txn, confOut->getPrimaryId());
             LOG(1) << "MR with single shard output, NS=" << finalColLong
                    << " primary=" << shard->toString();
 
@@ -481,7 +481,8 @@ public:
                 for (const auto& mrResult : mrCommandResults) {
                     string server;
                     {
-                        const auto shard = grid.shardRegistry()->getShard(mrResult.shardTargetId);
+                        const auto shard =
+                            grid.shardRegistry()->getShard(txn, mrResult.shardTargetId);
                         server = shard->getConnString().toString();
                     }
                     singleResult = mrResult.result;
diff --git a/src/mongo/s/commands/cluster_merge_chunks_cmd.cpp b/src/mongo/s/commands/cluster_merge_chunks_cmd.cpp
index 2c3802a8f3b..f040fafa4c6 100644
--- a/src/mongo/s/commands/cluster_merge_chunks_cmd.cpp
+++ b/src/mongo/s/commands/cluster_merge_chunks_cmd.cpp
@@ -183,7 +183,7 @@ public:
 
         // Throws, but handled at level above.  Don't want to rewrap to preserve exception
         // formatting.
-        const auto shard = grid.shardRegistry()->getShard(firstChunk->getShardId());
+        const auto shard = grid.shardRegistry()->getShard(txn, firstChunk->getShardId());
         if (!shard) {
             return appendCommandStatus(
                 result,
diff --git a/src/mongo/s/commands/cluster_move_chunk_cmd.cpp b/src/mongo/s/commands/cluster_move_chunk_cmd.cpp
index 9dc54bb633c..8f033427b6e 100644
--- a/src/mongo/s/commands/cluster_move_chunk_cmd.cpp
+++ b/src/mongo/s/commands/cluster_move_chunk_cmd.cpp
@@ -140,7 +140,7 @@ public:
             return false;
         }
 
-        const auto to = grid.shardRegistry()->getShard(toString);
+        const auto to = grid.shardRegistry()->getShard(txn, toString);
         if (!to) {
             string msg(str::stream() << "Could not move chunk in '" << nss.ns() << "' to shard '"
                                      << toString << "' because that shard does not exist");
@@ -208,7 +208,7 @@ public:
         }
 
         {
-            const auto from = grid.shardRegistry()->getShard(chunk->getShardId());
+            const auto from = grid.shardRegistry()->getShard(txn, chunk->getShardId());
             if (from->getId() == to->getId()) {
                 errmsg = "that chunk is already on that shard";
                 return false;
diff --git a/src/mongo/s/commands/cluster_move_primary_cmd.cpp b/src/mongo/s/commands/cluster_move_primary_cmd.cpp
index dff18f954c2..2736a962a9c 100644
--- a/src/mongo/s/commands/cluster_move_primary_cmd.cpp
+++ b/src/mongo/s/commands/cluster_move_primary_cmd.cpp
@@ -126,7 +126,7 @@ public:
             return false;
         }
 
-        shared_ptr<Shard> toShard = grid.shardRegistry()->getShard(to);
+        shared_ptr<Shard> toShard = grid.shardRegistry()->getShard(txn, to);
         if (!toShard) {
             string msg(str::stream() << "Could not move database '" << dbname << "' to shard '"
                                      << to << "' because the shard does not exist");
@@ -134,7 +134,7 @@ public:
             return appendCommandStatus(result, Status(ErrorCodes::ShardNotFound, msg));
         }
 
-        shared_ptr<Shard> fromShard = grid.shardRegistry()->getShard(config->getPrimaryId());
+        shared_ptr<Shard> fromShard = grid.shardRegistry()->getShard(txn, config->getPrimaryId());
         invariant(fromShard);
 
         if (fromShard->getConnString().sameLogicalEndpoint(toShard->getConnString())) {
diff --git a/src/mongo/s/commands/cluster_pipeline_cmd.cpp b/src/mongo/s/commands/cluster_pipeline_cmd.cpp
index ce272013709..820fa945ad9 100644
--- a/src/mongo/s/commands/cluster_pipeline_cmd.cpp
+++ b/src/mongo/s/commands/cluster_pipeline_cmd.cpp
@@ -110,7 +110,7 @@ public:
         shared_ptr<DBConfig> conf = status.getValue();
 
         if (!conf->isShardingEnabled()) {
-            return aggPassthrough(conf, cmdObj, result, options);
+            return aggPassthrough(txn, conf, cmdObj, result, options);
         }
 
         intrusive_ptr<ExpressionContext> mergeCtx =
@@ -131,7 +131,7 @@ public:
         }
 
         if (!conf->isSharded(fullns)) {
-            return aggPassthrough(conf, cmdObj, result, options);
+            return aggPassthrough(txn, conf, cmdObj, result, options);
         }
 
         // If the first $match stage is an exact match on the shard key, we only have to send it
@@ -234,7 +234,7 @@ public:
         const auto& mergingShardId = needPrimaryShardMerger
             ? conf->getPrimaryId()
             : shardResults[prng.nextInt32(shardResults.size())].shardTargetId;
-        const auto mergingShard = grid.shardRegistry()->getShard(mergingShardId);
+        const auto mergingShard = grid.shardRegistry()->getShard(txn, mergingShardId);
         ShardConnection conn(mergingShard->getConnString(), outputNsOrEmpty);
         BSONObj mergedResults =
             aggRunCommand(conn.get(), dbname, mergeCmd.freeze().toBson(), options);
@@ -261,7 +261,8 @@ private:
     // returned cursors with mongos's cursorCache.
     BSONObj aggRunCommand(DBClientBase* conn, const string& db, BSONObj cmd, int queryOptions);
 
-    bool aggPassthrough(shared_ptr<DBConfig> conf,
+    bool aggPassthrough(OperationContext* txn,
+                        shared_ptr<DBConfig> conf,
                         BSONObj cmd,
                         BSONObjBuilder& result,
                         int queryOptions);
@@ -398,12 +399,13 @@ BSONObj PipelineCommand::aggRunCommand(DBClientBase* conn,
     return result;
 }
 
-bool PipelineCommand::aggPassthrough(shared_ptr<DBConfig> conf,
+bool PipelineCommand::aggPassthrough(OperationContext* txn,
+                                     shared_ptr<DBConfig> conf,
                                      BSONObj cmd,
                                      BSONObjBuilder& out,
                                      int queryOptions) {
     // Temporary hack. See comment on declaration for details.
-    const auto shard = grid.shardRegistry()->getShard(conf->getPrimaryId());
+    const auto shard = grid.shardRegistry()->getShard(txn, conf->getPrimaryId());
     ShardConnection conn(shard->getConnString(), "");
     BSONObj result = aggRunCommand(conn.get(), conf->name(), cmd, queryOptions);
     conn.done();
diff --git a/src/mongo/s/commands/cluster_remove_shard_cmd.cpp b/src/mongo/s/commands/cluster_remove_shard_cmd.cpp
index a9ad5bd122d..c225bfa2f55 100644
--- a/src/mongo/s/commands/cluster_remove_shard_cmd.cpp
+++ b/src/mongo/s/commands/cluster_remove_shard_cmd.cpp
@@ -86,7 +86,7 @@ public:
                      BSONObjBuilder& result) {
         const string target = cmdObj.firstElement().valuestrsafe();
 
-        const auto s = grid.shardRegistry()->getShard(target);
+        const auto s = grid.shardRegistry()->getShard(txn, target);
         if (!s) {
             string msg(str::stream() << "Could not drop shard '" << target
                                      << "' because it does not exist");
diff --git a/src/mongo/s/commands/cluster_shard_collection_cmd.cpp b/src/mongo/s/commands/cluster_shard_collection_cmd.cpp
index c84946580f4..9a7cfa376c0 100644
--- a/src/mongo/s/commands/cluster_shard_collection_cmd.cpp
+++ b/src/mongo/s/commands/cluster_shard_collection_cmd.cpp
@@ -171,7 +171,7 @@ public:
         // The rest of the checks require a connection to the primary db
         ConnectionString shardConnString;
         {
-            const auto shard = grid.shardRegistry()->getShard(config->getPrimaryId());
+            const auto shard = grid.shardRegistry()->getShard(txn, config->getPrimaryId());
             shardConnString = shard->getConnString();
         }
 
@@ -416,7 +416,7 @@ public:
             int i = 0;
             for (ChunkMap::const_iterator c = chunkMap.begin(); c != chunkMap.end(); ++c, ++i) {
                 const ShardId& shardId = shardIds[i % numShards];
-                const auto to = grid.shardRegistry()->getShard(shardId);
+                const auto to = grid.shardRegistry()->getShard(txn, shardId);
                 if (!to) {
                     continue;
                 }
diff --git a/src/mongo/s/commands/cluster_write_cmd.cpp b/src/mongo/s/commands/cluster_write_cmd.cpp
index cea3c22307b..2a7176339fe 100644
--- a/src/mongo/s/commands/cluster_write_cmd.cpp
+++ b/src/mongo/s/commands/cluster_write_cmd.cpp
@@ -126,7 +126,7 @@ public:
         }
 
         return ClusterExplain::buildExplainResult(
-            shardResults, ClusterExplain::kWriteOnShards, timer.millis(), out);
+            txn, shardResults, ClusterExplain::kWriteOnShards, timer.millis(), out);
     }
 
     virtual bool run(OperationContext* txn,
@@ -265,7 +265,7 @@ private:
             const ShardEndpoint* endpoint = *it;
 
             ConnectionString host;
-            Status status = resolver.chooseWriteHost(endpoint->shardName, &host);
+            Status status = resolver.chooseWriteHost(txn, endpoint->shardName, &host);
             if (!status.isOK())
                 return status;
 
@@ -291,7 +291,7 @@ private:
             Strategy::CommandResult result;
             result.target = host;
             {
-                const auto shard = grid.shardRegistry()->getShard(host.toString());
+                const auto shard = grid.shardRegistry()->getShard(txn, host.toString());
                 result.shardTargetId = shard->getId();
             }
             result.result = response.toBSON();
diff --git a/src/mongo/s/commands/commands_public.cpp b/src/mongo/s/commands/commands_public.cpp
index 65ebfe77ad5..6a404bad604 100644
--- a/src/mongo/s/commands/commands_public.cpp
+++ b/src/mongo/s/commands/commands_public.cpp
@@ -100,30 +100,36 @@ public:
     }
 
 protected:
-    bool passthrough(shared_ptr<DBConfig> conf, const BSONObj& cmdObj, BSONObjBuilder& result) {
-        return _passthrough(conf->name(), conf, cmdObj, 0, result);
+    bool passthrough(OperationContext* txn,
+                     shared_ptr<DBConfig> conf,
+                     const BSONObj& cmdObj,
+                     BSONObjBuilder& result) {
+        return _passthrough(txn, conf->name(), conf, cmdObj, 0, result);
     }
 
-    bool adminPassthrough(shared_ptr<DBConfig> conf,
+    bool adminPassthrough(OperationContext* txn,
+                          shared_ptr<DBConfig> conf,
                           const BSONObj& cmdObj,
                           BSONObjBuilder& result) {
-        return _passthrough("admin", conf, cmdObj, 0, result);
+        return _passthrough(txn, "admin", conf, cmdObj, 0, result);
     }
 
-    bool passthrough(shared_ptr<DBConfig> conf,
+    bool passthrough(OperationContext* txn,
+                     shared_ptr<DBConfig> conf,
                      const BSONObj& cmdObj,
                      int options,
                      BSONObjBuilder& result) {
-        return _passthrough(conf->name(), conf, cmdObj, options, result);
+        return _passthrough(txn, conf->name(), conf, cmdObj, options, result);
     }
 
 private:
-    bool _passthrough(const string& db,
+    bool _passthrough(OperationContext* txn,
+                      const string& db,
                       shared_ptr<DBConfig> conf,
                       const BSONObj& cmdObj,
                       int options,
                       BSONObjBuilder& result) {
-        const auto shard = grid.shardRegistry()->getShard(conf->getPrimaryId());
+        const auto shard = grid.shardRegistry()->getShard(txn, conf->getPrimaryId());
         ShardConnection conn(shard->getConnString(), "");
 
         BSONObj res;
@@ -155,7 +161,7 @@ public:
         shared_ptr<DBConfig> conf = status.getValue();
 
         if (!conf->isShardingEnabled() || !conf->isSharded(fullns)) {
-            shardIds.push_back(conf->getShardId(fullns));
+            shardIds.push_back(conf->getShardId(txn, fullns));
         } else {
             grid.shardRegistry()->getAllShardIds(&shardIds);
         }
@@ -177,7 +183,7 @@ public:
 
         auto conf = uassertStatusOK(grid.catalogCache()->getDatabase(txn, dbName));
         if (!conf->isSharded(fullns)) {
-            return passthrough(conf, cmdObj, options, result);
+            return passthrough(txn, conf, cmdObj, options, result);
         }
 
         return appendCommandStatus(
@@ -407,7 +413,7 @@ public:
 
         shared_ptr<DBConfig> conf = status.getValue();
 
-        return passthrough(conf, cmdObj, result);
+        return passthrough(txn, conf, cmdObj, result);
     }
 
 } createCmd;
@@ -445,7 +451,7 @@ public:
         const auto& db = status.getValue();
         if (!db->isShardingEnabled() || !db->isSharded(fullns)) {
             log() << "\tdrop going to do passthrough";
-            return passthrough(db, cmdObj, result);
+            return passthrough(txn, db, cmdObj, result);
         }
 
         uassertStatusOK(grid.catalogManager(txn)->dropCollection(txn, NamespaceString(fullns)));
@@ -486,14 +492,14 @@ public:
         uassert(13138, "You can't rename a sharded collection", !confFrom->isSharded(fullnsFrom));
         uassert(13139, "You can't rename to a sharded collection", !confTo->isSharded(fullnsTo));
 
-        const ShardId& shardTo = confTo->getShardId(fullnsTo);
-        const ShardId& shardFrom = confFrom->getShardId(fullnsFrom);
+        const ShardId& shardTo = confTo->getShardId(txn, fullnsTo);
+        const ShardId& shardFrom = confFrom->getShardId(txn, fullnsFrom);
 
         uassert(13137,
                 "Source and destination collections must be on same shard",
                 shardFrom == shardTo);
 
-        return adminPassthrough(confFrom, cmdObj, result);
+        return adminPassthrough(txn, confFrom, cmdObj, result);
     }
 } renameCollectionCmd;
 
@@ -526,7 +532,7 @@ public:
 
         const string fromhost = cmdObj.getStringField("fromhost");
         if (!fromhost.empty()) {
-            return adminPassthrough(confTo, cmdObj, result);
+            return adminPassthrough(txn, confTo, cmdObj, result);
         } else {
             const string fromdb = cmdObj.getStringField("fromdb");
             uassert(13399, "need a fromdb argument", !fromdb.empty());
@@ -545,12 +551,12 @@ public:
             }
 
             {
-                const auto& shard = grid.shardRegistry()->getShard(confFrom->getPrimaryId());
+                const auto& shard = grid.shardRegistry()->getShard(txn, confFrom->getPrimaryId());
                 b.append("fromhost", shard->getConnString().toString());
             }
             BSONObj fixed = b.obj();
 
-            return adminPassthrough(confTo, fixed, result);
+            return adminPassthrough(txn, confTo, fixed, result);
         }
     }
 
@@ -580,7 +586,7 @@ public:
             result.appendBool("sharded", false);
             result.append("primary", conf->getPrimaryId());
 
-            return passthrough(conf, cmdObj, result);
+            return passthrough(txn, conf, cmdObj, result);
         }
 
         result.appendBool("sharded", true);
@@ -603,7 +609,7 @@ public:
         cm->getAllShardIds(&shardIds);
 
         for (const ShardId& shardId : shardIds) {
-            const auto shard = grid.shardRegistry()->getShard(shardId);
+            const auto shard = grid.shardRegistry()->getShard(txn, shardId);
             if (!shard) {
                 continue;
             }
@@ -741,7 +747,7 @@ public:
 
         auto conf = uassertStatusOK(grid.catalogCache()->getDatabase(txn, dbName));
         if (!conf->isShardingEnabled() || !conf->isSharded(fullns)) {
-            return passthrough(conf, cmdObj, result);
+            return passthrough(txn, conf, cmdObj, result);
         }
 
         ChunkManagerPtr cm = conf->getChunkManager(txn, fullns);
@@ -772,7 +778,7 @@ public:
         set<ShardId> shardIds;
         cm->getShardIdsForRange(shardIds, min, max);
         for (const ShardId& shardId : shardIds) {
-            const auto shard = grid.shardRegistry()->getShard(shardId);
+            const auto shard = grid.shardRegistry()->getShard(txn, shardId);
             if (!shard) {
                 continue;
             }
@@ -859,7 +865,7 @@ public:
         shardResults.push_back(singleResult);
 
         return ClusterExplain::buildExplainResult(
-            shardResults, ClusterExplain::kSingleShard, millisElapsed, out);
+            txn, shardResults, ClusterExplain::kSingleShard, millisElapsed, out);
     }
 
 } groupCmd;
@@ -931,7 +937,7 @@ public:
 
         shared_ptr<DBConfig> conf = status.getValue();
         if (!conf->isShardingEnabled() || !conf->isSharded(fullns)) {
-            return passthrough(conf, cmdObj, options, result);
+            return passthrough(txn, conf, cmdObj, options, result);
         }
 
         ChunkManagerPtr cm = conf->getChunkManager(txn, fullns);
@@ -945,7 +951,7 @@ public:
         int size = 32;
 
         for (const ShardId& shardId : shardIds) {
-            const auto shard = grid.shardRegistry()->getShard(shardId);
+            const auto shard = grid.shardRegistry()->getShard(txn, shardId);
             if (!shard) {
                 continue;
             }
@@ -1011,7 +1017,7 @@ public:
         const char* mongosStageName = ClusterExplain::getStageNameForReadOp(shardResults, cmdObj);
 
         return ClusterExplain::buildExplainResult(
-            shardResults, mongosStageName, millisElapsed, out);
+            txn, shardResults, mongosStageName, millisElapsed, out);
     }
 } disinctCmd;
 
@@ -1046,7 +1052,7 @@ public:
 
         auto conf = uassertStatusOK(grid.catalogCache()->getDatabase(txn, dbName));
         if (!conf->isShardingEnabled() || !conf->isSharded(fullns)) {
-            return passthrough(conf, cmdObj, result);
+            return passthrough(txn, conf, cmdObj, result);
         }
 
         ChunkManagerPtr cm = conf->getChunkManager(txn, fullns);
@@ -1174,7 +1180,7 @@ public:
 
         auto conf = uassertStatusOK(grid.catalogCache()->getDatabase(txn, dbName));
         if (!conf->isShardingEnabled() || !conf->isSharded(fullns)) {
-            return passthrough(conf, cmdObj, options, result);
+            return passthrough(txn, conf, cmdObj, options, result);
         }
 
         ChunkManagerPtr cm = conf->getChunkManager(txn, fullns);
@@ -1193,7 +1199,7 @@ public:
         list<shared_ptr<Future::CommandResult>> futures;
         BSONArrayBuilder shardArray;
         for (const ShardId& shardId : shardIds) {
-            const auto shard = grid.shardRegistry()->getShard(shardId);
+            const auto shard = grid.shardRegistry()->getShard(txn, shardId);
             if (!shard) {
                 continue;
             }
@@ -1344,7 +1350,7 @@ public:
         }
 
         shared_ptr<DBConfig> conf = status.getValue();
-        return passthrough(conf, cmdObj, result);
+        return passthrough(txn, conf, cmdObj, result);
     }
 } evalCmd;
 
@@ -1384,9 +1390,9 @@ public:
         }
 
         shared_ptr<DBConfig> conf = status.getValue();
-        bool retval = passthrough(conf, cmdObj, result);
+        bool retval = passthrough(txn, conf, cmdObj, result);
 
-        const auto shard = grid.shardRegistry()->getShard(conf->getPrimaryId());
+        const auto shard = grid.shardRegistry()->getShard(txn, conf->getPrimaryId());
         Status storeCursorStatus =
             storePossibleCursor(shard->getConnString().toString(), result.asTempObj());
         if (!storeCursorStatus.isOK()) {
@@ -1416,9 +1422,9 @@ public:
              string& errmsg,
              BSONObjBuilder& result) {
         auto conf = uassertStatusOK(grid.catalogCache()->getDatabase(txn, dbName));
-        bool retval = passthrough(conf, cmdObj, result);
+        bool retval = passthrough(txn, conf, cmdObj, result);
 
-        const auto shard = grid.shardRegistry()->getShard(conf->getPrimaryId());
+        const auto shard = grid.shardRegistry()->getShard(txn, conf->getPrimaryId());
         Status storeCursorStatus =
             storePossibleCursor(shard->getConnString().toString(), result.asTempObj());
         if (!storeCursorStatus.isOK()) {
diff --git a/src/mongo/s/commands/run_on_all_shards_cmd.cpp b/src/mongo/s/commands/run_on_all_shards_cmd.cpp
index 91b10dd1db0..157c556d65a 100644
--- a/src/mongo/s/commands/run_on_all_shards_cmd.cpp
+++ b/src/mongo/s/commands/run_on_all_shards_cmd.cpp
@@ -86,7 +86,7 @@ bool RunOnAllShardsCommand::run(OperationContext* txn,
 
     std::list<std::shared_ptr<Future::CommandResult>> futures;
     for (const ShardId& shardId : shardIds) {
-        const auto shard = grid.shardRegistry()->getShard(shardId);
+        const auto shard = grid.shardRegistry()->getShard(txn, shardId);
         if (!shard) {
             continue;
         }
diff --git a/src/mongo/s/config.cpp b/src/mongo/s/config.cpp
index 6d4977089d0..0f6a0918fa9 100644
--- a/src/mongo/s/config.cpp
+++ b/src/mongo/s/config.cpp
@@ -164,10 +164,10 @@ bool DBConfig::isSharded(const string& ns) {
     return i->second.isSharded();
 }
 
-const ShardId& DBConfig::getShardId(const string& ns) {
+const ShardId& DBConfig::getShardId(OperationContext* txn, const string& ns) {
     uassert(28679, "ns can't be sharded", !isSharded(ns));
 
-    uassert(10178, "no primary!", grid.shardRegistry()->getShard(_primaryId));
+    uassert(10178, "no primary!", grid.shardRegistry()->getShard(txn, _primaryId));
     return _primaryId;
 }
 
@@ -220,7 +220,8 @@ bool DBConfig::removeSharding(OperationContext* txn, const string& ns) {
 
 // Handles weird logic related to getting *either* a chunk manager *or* the collection primary
 // shard
-void DBConfig::getChunkManagerOrPrimary(const string& ns,
+void DBConfig::getChunkManagerOrPrimary(OperationContext* txn,
+                                        const string& ns,
                                         std::shared_ptr<ChunkManager>& manager,
                                         std::shared_ptr<Shard>& primary) {
     // The logic here is basically that at any time, our collection can become sharded or
@@ -239,7 +240,7 @@ void DBConfig::getChunkManagerOrPrimary(const string& ns,
         // No namespace
         if (i == _collections.end()) {
             // If we don't know about this namespace, it's unsharded by default
-            primary = grid.shardRegistry()->getShard(_primaryId);
+            primary = grid.shardRegistry()->getShard(txn, _primaryId);
         } else {
             CollectionInfo& cInfo = i->second;
 
@@ -250,7 +251,7 @@ void DBConfig::getChunkManagerOrPrimary(const string& ns,
             if (_shardingEnabled && cInfo.isSharded()) {
                 manager = cInfo.getCM();
             } else {
-                primary = grid.shardRegistry()->getShard(_primaryId);
+                primary = grid.shardRegistry()->getShard(txn, _primaryId);
             }
         }
     }
@@ -428,7 +429,7 @@ std::shared_ptr<ChunkManager> DBConfig::getChunkManager(OperationContext* txn,
 }
 
 void DBConfig::setPrimary(OperationContext* txn, const std::string& s) {
-    const auto shard = grid.shardRegistry()->getShard(s);
+    const auto shard = grid.shardRegistry()->getShard(txn, s);
 
     stdx::lock_guard<stdx::mutex> lk(_lock);
     _primaryId = shard->getId();
@@ -572,7 +573,7 @@ bool DBConfig::dropDatabase(OperationContext* txn, string& errmsg) {
 
     // 3
     {
-        const auto shard = grid.shardRegistry()->getShard(_primaryId);
+        const auto shard = grid.shardRegistry()->getShard(txn, _primaryId);
         ScopedDbConnection conn(shard->getConnString(), 30.0);
         BSONObj res;
         if (!conn->dropDatabase(_name, &res)) {
@@ -584,7 +585,7 @@ bool DBConfig::dropDatabase(OperationContext* txn, string& errmsg) {
 
     // 4
     for (const ShardId& shardId : shardIds) {
-        const auto shard = grid.shardRegistry()->getShard(shardId);
+        const auto shard = grid.shardRegistry()->getShard(txn, shardId);
         if (!shard) {
             continue;
         }
diff --git a/src/mongo/s/config.h b/src/mongo/s/config.h
index 6c5d362f2b3..d01a2951664 100644
--- a/src/mongo/s/config.h
+++ b/src/mongo/s/config.h
@@ -145,7 +145,8 @@ public:
 
     // Atomically returns *either* the chunk manager *or* the primary shard for the collection,
     // neither if the collection doesn't exist.
-    void getChunkManagerOrPrimary(const std::string& ns,
+    void getChunkManagerOrPrimary(OperationContext* txn,
+                                  const std::string& ns,
                                   std::shared_ptr<ChunkManager>& manager,
                                   std::shared_ptr<Shard>& primary);
 
@@ -161,7 +162,7 @@ public:
     /**
      * Returns shard id for primary shard for the database for which this DBConfig represents.
      */
-    const ShardId& getShardId(const std::string& ns);
+    const ShardId& getShardId(OperationContext* txn, const std::string& ns);
 
     void setPrimary(OperationContext* txn, const std::string& s);
 
diff --git a/src/mongo/s/d_migrate.cpp b/src/mongo/s/d_migrate.cpp
index f74d1b45265..cf687a61a66 100644
--- a/src/mongo/s/d_migrate.cpp
+++ b/src/mongo/s/d_migrate.cpp
@@ -417,7 +417,7 @@ public:
         // Make sure we're as up-to-date as possible with shard information
         // This catches the case where we had to previously changed a shard's host by
         // removing/adding a shard with the same name
-        grid.shardRegistry()->reload();
+        grid.shardRegistry()->reload(txn);
 
         MoveTimingHelper timing(
             txn, "from", ns, min, max, 6 /* steps */, &errmsg, toShardName, fromShardName);
@@ -547,7 +547,7 @@ public:
 
         // Resolve the shard connection strings.
         {
-            std::shared_ptr<Shard> fromShard = grid.shardRegistry()->getShard(fromShardName);
+            std::shared_ptr<Shard> fromShard = grid.shardRegistry()->getShard(txn, fromShardName);
             uassert(28674,
                     str::stream() << "Source shard " << fromShardName
                                   << " is missing. This indicates metadata corruption.",
@@ -555,7 +555,7 @@ public:
 
             fromShardCS = fromShard->getConnString();
 
-            std::shared_ptr<Shard> toShard = grid.shardRegistry()->getShard(toShardName);
+            std::shared_ptr<Shard> toShard = grid.shardRegistry()->getShard(txn, toShardName);
             uassert(28675,
                     str::stream() << "Destination shard " << toShardName
                                   << " is missing. This indicates metadata corruption.",
diff --git a/src/mongo/s/dbclient_shard_resolver.cpp b/src/mongo/s/dbclient_shard_resolver.cpp
index 92694a51243..bc7dc38fb27 100644
--- a/src/mongo/s/dbclient_shard_resolver.cpp
+++ b/src/mongo/s/dbclient_shard_resolver.cpp
@@ -39,10 +39,11 @@ namespace mongo {
 
 using std::string;
 
-Status DBClientShardResolver::chooseWriteHost(const string& shardName,
+Status DBClientShardResolver::chooseWriteHost(OperationContext* txn,
+                                              const string& shardName,
                                               ConnectionString* shardHost) const {
     // Internally uses our shard cache, does no reload
-    std::shared_ptr<Shard> shard = grid.shardRegistry()->getShard(shardName);
+    std::shared_ptr<Shard> shard = grid.shardRegistry()->getShard(txn, shardName);
     if (!shard) {
         return Status(ErrorCodes::ShardNotFound,
                       str::stream() << "unknown shard name " << shardName);
diff --git a/src/mongo/s/dbclient_shard_resolver.h b/src/mongo/s/dbclient_shard_resolver.h
index 076dd078562..ba70bdf1dc3 100644
--- a/src/mongo/s/dbclient_shard_resolver.h
+++ b/src/mongo/s/dbclient_shard_resolver.h
@@ -54,7 +54,9 @@ public:
      * Returns ReplicaSetNotFound if the replica set is not being tracked
      * Returns !OK with message if the shard host could not be found for other reasons.
      */
-    Status chooseWriteHost(const std::string& shardName, ConnectionString* shardHost) const;
+    Status chooseWriteHost(OperationContext* txn,
+                           const std::string& shardName,
+                           ConnectionString* shardHost) const override;
 
     /**
      * Resolves a replica set connection string to a master or returns an error.
diff --git a/src/mongo/s/mock_shard_resolver.h b/src/mongo/s/mock_shard_resolver.h
index 7816556abe9..d2263274436 100644
--- a/src/mongo/s/mock_shard_resolver.h
+++ b/src/mongo/s/mock_shard_resolver.h
@@ -41,7 +41,9 @@ class MockShardResolver : public ShardResolver {
 public:
     virtual ~MockShardResolver() {}
 
-    Status chooseWriteHost(const std::string& shardName, ConnectionString* shardHost) const {
+    Status chooseWriteHost(OperationContext* txn,
+                           const std::string& shardName,
+                           ConnectionString* shardHost) const {
         *shardHost =
             unittest::assertGet(ConnectionString::parse(std::string("$") + shardName + ":12345"));
         return Status::OK();
diff --git a/src/mongo/s/query/cluster_find.cpp b/src/mongo/s/query/cluster_find.cpp
index 7441a613124..29dd5ab74dd 100644
--- a/src/mongo/s/query/cluster_find.cpp
+++ b/src/mongo/s/query/cluster_find.cpp
@@ -113,7 +113,7 @@ StatusWith<CursorId> runQueryWithoutRetrying(OperationContext* txn,
         chunkManager->getShardIdsForQuery(shardIds, query.getParsed().getFilter());
 
         for (auto id : shardIds) {
-            shards.emplace_back(shardRegistry->getShard(id));
+            shards.emplace_back(shardRegistry->getShard(txn, id));
         }
     }
 
@@ -233,7 +233,7 @@ StatusWith<CursorId> ClusterFind::runQuery(OperationContext* txn,
 
     std::shared_ptr<ChunkManager> chunkManager;
     std::shared_ptr<Shard> primary;
-    dbConfig.getValue()->getChunkManagerOrPrimary(query.nss().ns(), chunkManager, primary);
+    dbConfig.getValue()->getChunkManagerOrPrimary(txn, query.nss().ns(), chunkManager, primary);
 
     // Re-target and re-send the initial find command to the shards until we have established the
     // shard version.
diff --git a/src/mongo/s/shard_resolver.h b/src/mongo/s/shard_resolver.h
index 6c229290805..4a0fa53f48c 100644
--- a/src/mongo/s/shard_resolver.h
+++ b/src/mongo/s/shard_resolver.h
@@ -36,6 +36,8 @@
 
 namespace mongo {
 
+class OperationContext;
+
 /**
  * Given a shard name, the ShardResolver resolves a particular host on that shard to contact.
  *
@@ -51,7 +53,8 @@ public:
      *
      * Returns !OK with message if the shard host could not be found for other reasons.
      */
-    virtual Status chooseWriteHost(const std::string& shardName,
+    virtual Status chooseWriteHost(OperationContext* txn,
+                                   const std::string& shardName,
                                    ConnectionString* shardHost) const = 0;
 };
 
diff --git a/src/mongo/s/shard_util.cpp b/src/mongo/s/shard_util.cpp
index 53e4b0c0eb2..21d25e539ab 100644
--- a/src/mongo/s/shard_util.cpp
+++ b/src/mongo/s/shard_util.cpp
@@ -39,8 +39,10 @@
 namespace mongo {
 namespace shardutil {
 
-StatusWith<long long> retrieveTotalShardSize(ShardId shardId, ShardRegistry* shardRegistry) {
-    auto shard = shardRegistry->getShard(shardId);
+StatusWith<long long> retrieveTotalShardSize(OperationContext* txn,
+                                             ShardId shardId,
+                                             ShardRegistry* shardRegistry) {
+    auto shard = shardRegistry->getShard(txn, shardId);
     if (!shard) {
         return {ErrorCodes::ShardNotFound, str::stream() << "shard " << shardId << " not found"};
     }
diff --git a/src/mongo/s/shard_util.h b/src/mongo/s/shard_util.h
index b9d546b75a2..640dd09d5c1 100644
--- a/src/mongo/s/shard_util.h
+++ b/src/mongo/s/shard_util.h
@@ -34,6 +34,7 @@
 
 namespace mongo {
 
+class OperationContext;
 class ShardRegistry;
 template <typename T>
 class StatusWith;
@@ -50,7 +51,9 @@ namespace shardutil {
  *  ShardNotFound if shard by that id is not available on the registry
  *  NoSuchKey if the total shard size could not be retrieved
  */
-StatusWith<long long> retrieveTotalShardSize(ShardId shardId, ShardRegistry* shardRegistry);
+StatusWith<long long> retrieveTotalShardSize(OperationContext* txn,
+                                             ShardId shardId,
+                                             ShardRegistry* shardRegistry);
 };
 
 }  // namespace mongo
diff --git a/src/mongo/s/strategy.cpp b/src/mongo/s/strategy.cpp
index 2a21d11208c..f0ff5d58c29 100644
--- a/src/mongo/s/strategy.cpp
+++ b/src/mongo/s/strategy.cpp
@@ -113,12 +113,12 @@ static bool doShardedIndexQuery(OperationContext* txn, Request& r, const QuerySp
 
     ShardPtr shard;
     ChunkManagerPtr cm;
-    config->getChunkManagerOrPrimary(indexNSSQuery.ns(), cm, shard);
+    config->getChunkManagerOrPrimary(txn, indexNSSQuery.ns(), cm, shard);
     if (cm) {
         set<ShardId> shardIds;
         cm->getAllShardIds(&shardIds);
         verify(shardIds.size() > 0);
-        shard = grid.shardRegistry()->getShard(*shardIds.begin());
+        shard = grid.shardRegistry()->getShard(txn, *shardIds.begin());
     }
 
     ShardConnection dbcon(shard->getConnString(), r.getns());
@@ -304,7 +304,7 @@ void Strategy::queryOp(OperationContext* txn, Request& r) {
         // Remote cursors are stored remotely, we shouldn't need this around.
         unique_ptr<ParallelSortClusteredCursor> cursorDeleter(cursor);
 
-        ShardPtr shard = cursor->getQueryShard();
+        ShardPtr shard = grid.shardRegistry()->getShard(txn, cursor->getQueryShardId());
         verify(shard.get());
         DBClientCursorPtr shardCursor = cursor->getShardCursor(shard->getId());
 
@@ -491,7 +491,7 @@ Status Strategy::commandOpUnsharded(OperationContext* txn,
         return Status(ErrorCodes::IllegalOperation, ss);
     }
 
-    const auto primaryShard = grid.shardRegistry()->getShard(conf->getPrimaryId());
+    const auto primaryShard = grid.shardRegistry()->getShard(txn, conf->getPrimaryId());
 
     BSONObj shardResult;
     try {
@@ -577,7 +577,7 @@ void Strategy::getMore(OperationContext* txn, Request& r) {
 
     ShardPtr primary;
     ChunkManagerPtr info;
-    config->getChunkManagerOrPrimary(ns, info, primary);
+    config->getChunkManagerOrPrimary(txn, ns, info, primary);
 
     //
     // TODO: Cleanup cursor cache, consolidate into single codepath
diff --git a/src/mongo/s/version_manager.cpp b/src/mongo/s/version_manager.cpp
index 54c9299195e..8aa785b6d20 100644
--- a/src/mongo/s/version_manager.cpp
+++ b/src/mongo/s/version_manager.cpp
@@ -108,7 +108,8 @@ private:
 /**
  * Sends the setShardVersion command on the specified connection.
  */
-bool setShardVersion(DBClientBase& conn,
+bool setShardVersion(OperationContext* txn,
+                     DBClientBase& conn,
                      const string& ns,
                      const ConnectionString& configServer,
                      ChunkVersion version,
@@ -118,7 +119,7 @@ bool setShardVersion(DBClientBase& conn,
     ShardId shardId;
     ConnectionString shardCS;
     {
-        const auto shard = grid.shardRegistry()->getShard(conn.getServerAddress());
+        const auto shard = grid.shardRegistry()->getShard(txn, conn.getServerAddress());
         shardId = shard->getId();
         shardCS = shard->getConnString();
     }
@@ -205,14 +206,15 @@ bool initShardVersionEmptyNS(OperationContext* txn, DBClientBase* conn_in) {
         // Check to see if this is actually a shard and not a single config server
         // NOTE: Config servers are registered only by the name "config" in the shard cache, not
         // by host, so lookup by host will fail unless the host is also a shard.
-        const auto shard = grid.shardRegistry()->getShard(conn->getServerAddress());
+        const auto shard = grid.shardRegistry()->getShard(txn, conn->getServerAddress());
         if (!shard) {
             return false;
         }
 
         LOG(1) << "initializing shard connection to " << shard->toString();
 
-        ok = setShardVersion(*conn,
+        ok = setShardVersion(txn,
+                             *conn,
                              "",
                              grid.shardRegistry()->getConfigServerConnectionString(),
                              ChunkVersion(),
@@ -301,7 +303,7 @@ bool checkShardVersion(OperationContext* txn,
     shared_ptr<Shard> primary;
     shared_ptr<ChunkManager> manager;
 
-    conf->getChunkManagerOrPrimary(ns, manager, primary);
+    conf->getChunkManagerOrPrimary(txn, ns, manager, primary);
 
     unsigned long long officialSequenceNumber = 0;
 
@@ -313,7 +315,7 @@ bool checkShardVersion(OperationContext* txn,
         return false;
     }
 
-    const auto shard = grid.shardRegistry()->getShard(conn->getServerAddress());
+    const auto shard = grid.shardRegistry()->getShard(txn, conn->getServerAddress());
     uassert(ErrorCodes::ShardNotFound,
             str::stream() << conn->getServerAddress() << " is not recognized as a shard",
             shard);
@@ -368,7 +370,8 @@ bool checkShardVersion(OperationContext* txn,
            << ", current chunk manager iteration is " << officialSequenceNumber;
 
     BSONObj result;
-    if (setShardVersion(*conn,
+    if (setShardVersion(txn,
+                        *conn,
                         ns,
                         grid.shardRegistry()->getConfigServerConnectionString(),
                         version,
diff --git a/src/mongo/s/write_ops/batch_write_exec.cpp b/src/mongo/s/write_ops/batch_write_exec.cpp
index 9891b182e29..87d5dfe779e 100644
--- a/src/mongo/s/write_ops/batch_write_exec.cpp
+++ b/src/mongo/s/write_ops/batch_write_exec.cpp
@@ -180,7 +180,7 @@ void BatchWriteExec::executeBatch(OperationContext* txn,
                 // Figure out what host we need to dispatch our targeted batch
                 ConnectionString shardHost;
                 Status resolveStatus =
-                    _resolver->chooseWriteHost(nextBatch->getEndpoint().shardName, &shardHost);
+                    _resolver->chooseWriteHost(txn, nextBatch->getEndpoint().shardName, &shardHost);
                 if (!resolveStatus.isOK()) {
                     ++_stats->numResolveErrors;
 
diff --git a/src/mongo/s/write_ops/batch_write_exec_test.cpp b/src/mongo/s/write_ops/batch_write_exec_test.cpp
index 65658935818..19c851d1ee0 100644
--- a/src/mongo/s/write_ops/batch_write_exec_test.cpp
+++ b/src/mongo/s/write_ops/batch_write_exec_test.cpp
@@ -52,7 +52,7 @@ namespace {
  */
 class MockSingleShardBackend {
 public:
-    MockSingleShardBackend(const NamespaceString& nss) {
+    MockSingleShardBackend(OperationContext* txn, const NamespaceString& nss) {
         // Initialize targeting to a mock shard
         ShardEndpoint endpoint("shard", ChunkVersion::IGNORED());
         vector<MockRange*> mockRanges;
@@ -61,7 +61,7 @@ public:
         targeter.init(mockRanges);
 
         // Get the connection string for the mock shard
-        resolver.chooseWriteHost(mockRanges.front()->endpoint.shardName, &shardHost);
+        resolver.chooseWriteHost(txn, mockRanges.front()->endpoint.shardName, &shardHost);
 
         // Executor using the mock backend
         exec.reset(new BatchWriteExec(&targeter, &resolver, &dispatcher));
@@ -92,7 +92,7 @@ TEST(BatchWriteExecTests, SingleOp) {
     OperationContextNoop txn;
     NamespaceString nss("foo.bar");
 
-    MockSingleShardBackend backend(nss);
+    MockSingleShardBackend backend(&txn, nss);
 
     BatchedCommandRequest request(BatchedCommandRequest::BatchType_Insert);
     request.setNS(nss);
@@ -117,7 +117,7 @@ TEST(BatchWriteExecTests, SingleOpError) {
     OperationContextNoop txn;
     NamespaceString nss("foo.bar");
 
-    MockSingleShardBackend backend(nss);
+    MockSingleShardBackend backend(&txn, nss);
 
     vector<MockWriteResult*> mockResults;
     BatchedCommandResponse errResponse;
@@ -168,7 +168,7 @@ TEST(BatchWriteExecTests, StaleOp) {
     // Do single-target, single doc batch write op
     request.getInsertRequest()->addToDocuments(BSON("x" << 1));
 
-    MockSingleShardBackend backend(nss);
+    MockSingleShardBackend backend(&txn, nss);
 
     vector<MockWriteResult*> mockResults;
     WriteErrorDetail error;
@@ -203,7 +203,7 @@ TEST(BatchWriteExecTests, MultiStaleOp) {
     // Do single-target, single doc batch write op
     request.getInsertRequest()->addToDocuments(BSON("x" << 1));
 
-    MockSingleShardBackend backend(nss);
+    MockSingleShardBackend backend(&txn, nss);
 
     vector<MockWriteResult*> mockResults;
     WriteErrorDetail error;
@@ -243,7 +243,7 @@ TEST(BatchWriteExecTests, TooManyStaleOp) {
     request.getInsertRequest()->addToDocuments(BSON("x" << 1));
     request.getInsertRequest()->addToDocuments(BSON("x" << 2));
 
-    MockSingleShardBackend backend(nss);
+    MockSingleShardBackend backend(&txn, nss);
 
     vector<MockWriteResult*> mockResults;
     WriteErrorDetail error;
@@ -282,7 +282,7 @@ TEST(BatchWriteExecTests, ManyStaleOpWithMigration) {
     // Do single-target, single doc batch write op
     request.getInsertRequest()->addToDocuments(BSON("x" << 1));
 
-    MockSingleShardBackend backend(nss);
+    MockSingleShardBackend backend(&txn, nss);
 
     vector<MockWriteResult*> mockResults;
     WriteErrorDetail error;