SERVER-22671 adding migration status to serverStatus' sharding section

17 files changed, 337 insertions, 46 deletions

diff --git a/src/mongo/db/s/SConscript b/src/mongo/db/s/SConscript
index d6369675030..d892b0ca8dd 100644
--- a/src/mongo/db/s/SConscript
+++ b/src/mongo/db/s/SConscript
@@ -55,6 +55,7 @@ env.Library(
         'migration_chunk_cloner_source_legacy.cpp',
         'migration_destination_manager.cpp',
         'migration_source_manager.cpp',
+        'migration_util.cpp',
         'move_timing_helper.cpp',
         'operation_sharding_state.cpp',
         'shard_identity_rollback_notifier.cpp',
diff --git a/src/mongo/db/s/active_migrations_registry.cpp b/src/mongo/db/s/active_migrations_registry.cpp
index 70e69a05f66..93f06c813db 100644
--- a/src/mongo/db/s/active_migrations_registry.cpp
+++ b/src/mongo/db/s/active_migrations_registry.cpp
@@ -31,6 +31,9 @@
 #include "mongo/db/s/active_migrations_registry.h"
 
 #include "mongo/base/status_with.h"
+#include "mongo/db/db_raii.h"
+#include "mongo/db/s/collection_sharding_state.h"
+#include "mongo/db/s/migration_source_manager.h"
 #include "mongo/util/assert_util.h"
 
 namespace mongo {
@@ -68,6 +71,33 @@ boost::optional<NamespaceString> ActiveMigrationsRegistry::getActiveMigrationNss
     return boost::none;
 }
 
+BSONObj ActiveMigrationsRegistry::getActiveMigrationStatusReport(OperationContext* txn) {
+    boost::optional<NamespaceString> nss;
+    {
+        stdx::lock_guard<stdx::mutex> lk(_mutex);
+
+        if (_activeMoveChunkState) {
+            nss = _activeMoveChunkState->args.getNss();
+        }
+    }
+
+    // The state of the MigrationSourceManager could change between taking and releasing the mutex
+    // above and then taking the collection lock here, but that's fine because it isn't important
+    // to return information on a migration that just ended or started. This is just best effort and
+    // desireable for reporting, and then diagnosing, migrations that are stuck.
+    if (nss) {
+        // Lock the collection so nothing changes while we're getting the migration report.
+        AutoGetCollection autoColl(txn, nss.get(), MODE_IS);
+
+        auto css = CollectionShardingState::get(txn, nss.get());
+        if (css && css->getMigrationSourceManager()) {
+            return css->getMigrationSourceManager()->getMigrationStatusReport();
+        }
+    }
+
+    return BSONObj();
+}
+
 void ActiveMigrationsRegistry::_clearMigration() {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
     invariant(_activeMoveChunkState);
diff --git a/src/mongo/db/s/active_migrations_registry.h b/src/mongo/db/s/active_migrations_registry.h
index 37ccbb1b9b9..1415a4c469f 100644
--- a/src/mongo/db/s/active_migrations_registry.h
+++ b/src/mongo/db/s/active_migrations_registry.h
@@ -63,7 +63,7 @@ public:
      * arguments, returns a ScopedRegisterMigration, which can be used to join the already running
      * migration.
      *
-     * Othwerwise returns a ConflictingOperationInProgress error.
+     * Otherwise returns a ConflictingOperationInProgress error.
      */
     StatusWith<ScopedRegisterMigration> registerMigration(const MoveChunkRequest& args);
 
@@ -73,6 +73,14 @@ public:
      */
     boost::optional<NamespaceString> getActiveMigrationNss();
 
+    /**
+     * Returns a report on the active migration if there currently is one. Otherwise, returns an
+     * empty BSONObj.
+     *
+     * Takes an IS lock on the namespace of the active migration, if one is active.
+     */
+    BSONObj getActiveMigrationStatusReport(OperationContext* txn);
+
 private:
     friend class ScopedRegisterMigration;
 
diff --git a/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp b/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
index 08721b06419..2a2d2e77d3e 100644
--- a/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
+++ b/src/mongo/db/s/migration_chunk_cloner_source_legacy.cpp
@@ -212,6 +212,7 @@ Status MigrationChunkClonerSourceLegacy::startClone(OperationContext* txn) {
                                             _sessionId,
                                             _args.getConfigServerCS(),
                                             _donorCS,
+                                            _args.getFromShardId(),
                                             _args.getToShardId(),
                                             _args.getMinKey(),
                                             _args.getMaxKey(),
diff --git a/src/mongo/db/s/migration_destination_manager.cpp b/src/mongo/db/s/migration_destination_manager.cpp
index 3e4ad61b94a..87b45e9df03 100644
--- a/src/mongo/db/s/migration_destination_manager.cpp
+++ b/src/mongo/db/s/migration_destination_manager.cpp
@@ -53,6 +53,7 @@
 #include "mongo/db/repl/replication_coordinator_global.h"
 #include "mongo/db/s/collection_metadata.h"
 #include "mongo/db/s/collection_sharding_state.h"
+#include "mongo/db/s/migration_util.h"
 #include "mongo/db/s/move_timing_helper.h"
 #include "mongo/db/s/sharded_connection_info.h"
 #include "mongo/db/s/sharding_state.h"
@@ -216,6 +217,10 @@ void MigrationDestinationManager::setState(State newState) {
 
 bool MigrationDestinationManager::isActive() const {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
+    return _isActive_inlock();
+}
+
+bool MigrationDestinationManager::_isActive_inlock() const {
     return _sessionId.is_initialized();
 }
 
@@ -228,8 +233,8 @@ void MigrationDestinationManager::report(BSONObjBuilder& b) {
         b.append("sessionId", _sessionId->toString());
     }
 
-    b.append("ns", _ns);
-    b.append("from", _from);
+    b.append("ns", _nss.ns());
+    b.append("from", _fromShardConnString.toString());
     b.append("min", _min);
     b.append("max", _max);
     b.append("shardKeyPattern", _shardKeyPattern);
@@ -248,9 +253,21 @@ void MigrationDestinationManager::report(BSONObjBuilder& b) {
     bb.done();
 }
 
+BSONObj MigrationDestinationManager::getMigrationStatusReport() {
+    stdx::lock_guard<stdx::mutex> lk(_mutex);
+    if (_isActive_inlock()) {
+        return migrationutil::makeMigrationStatusDocument(
+            _nss, _fromShard, _toShard, false, _min, _max);
+    } else {
+        return BSONObj();
+    }
+}
+
 Status MigrationDestinationManager::start(const string& ns,
                                           const MigrationSessionId& sessionId,
-                                          const string& fromShard,
+                                          const ConnectionString& fromShardConnString,
+                                          const ShardId& fromShard,
+                                          const ShardId& toShard,
                                           const BSONObj& min,
                                           const BSONObj& max,
                                           const BSONObj& shardKeyPattern,
@@ -262,9 +279,9 @@ Status MigrationDestinationManager::start(const string& ns,
         return Status(ErrorCodes::ConflictingOperationInProgress,
                       str::stream() << "Active migration already in progress "
                                     << "ns: "
-                                    << _ns
+                                    << _nss.ns()
                                     << ", from: "
-                                    << _from
+                                    << _fromShardConnString.toString()
                                     << ", min: "
                                     << _min
                                     << ", max: "
@@ -274,8 +291,10 @@ Status MigrationDestinationManager::start(const string& ns,
     _state = READY;
     _errmsg = "";
 
-    _ns = ns;
-    _from = fromShard;
+    _nss = NamespaceString(ns);
+    _fromShardConnString = fromShardConnString;
+    _fromShard = fromShard;
+    _toShard = toShard;
     _min = min;
     _max = max;
     _shardKeyPattern = shardKeyPattern;
@@ -296,11 +315,18 @@ Status MigrationDestinationManager::start(const string& ns,
         _migrateThreadHandle.join();
     }
 
-    _migrateThreadHandle = stdx::thread(
-        [this, ns, sessionId, min, max, shardKeyPattern, fromShard, epoch, writeConcern]() {
-            _migrateThread(
-                ns, sessionId, min, max, shardKeyPattern, fromShard, epoch, writeConcern);
-        });
+    _migrateThreadHandle = stdx::thread([this,
+                                         ns,
+                                         sessionId,
+                                         min,
+                                         max,
+                                         shardKeyPattern,
+                                         fromShardConnString,
+                                         epoch,
+                                         writeConcern]() {
+        _migrateThread(
+            ns, sessionId, min, max, shardKeyPattern, fromShardConnString, epoch, writeConcern);
+    });
 
     return Status::OK();
 }
@@ -357,7 +383,7 @@ void MigrationDestinationManager::_migrateThread(std::string ns,
                                                  BSONObj min,
                                                  BSONObj max,
                                                  BSONObj shardKeyPattern,
-                                                 std::string fromShard,
+                                                 ConnectionString fromShardConnString,
                                                  OID epoch,
                                                  WriteConcernOptions writeConcern) {
     Client::initThread("migrateThread");
@@ -369,8 +395,15 @@ void MigrationDestinationManager::_migrateThread(std::string ns,
     }
 
     try {
-        _migrateDriver(
-            opCtx.get(), ns, sessionId, min, max, shardKeyPattern, fromShard, epoch, writeConcern);
+        _migrateDriver(opCtx.get(),
+                       ns,
+                       sessionId,
+                       min,
+                       max,
+                       shardKeyPattern,
+                       fromShardConnString,
+                       epoch,
+                       writeConcern);
     } catch (std::exception& e) {
         {
             stdx::lock_guard<stdx::mutex> sl(_mutex);
@@ -408,7 +441,7 @@ void MigrationDestinationManager::_migrateDriver(OperationContext* txn,
                                                  const BSONObj& min,
                                                  const BSONObj& max,
                                                  const BSONObj& shardKeyPattern,
-                                                 const std::string& fromShard,
+                                                 const ConnectionString& fromShardConnString,
                                                  const OID& epoch,
                                                  const WriteConcernOptions& writeConcern) {
     invariant(isActive());
@@ -416,7 +449,8 @@ void MigrationDestinationManager::_migrateDriver(OperationContext* txn,
     invariant(!max.isEmpty());
 
     log() << "starting receiving-end of migration of chunk " << min << " -> " << max
-          << " for collection " << ns << " from " << fromShard << " at epoch " << epoch.toString();
+          << " for collection " << ns << " from " << fromShardConnString << " at epoch "
+          << epoch.toString();
 
     string errmsg;
     MoveTimingHelper timing(txn, "to", ns, min, max, 6 /* steps */, &errmsg, ShardId(), ShardId());
@@ -431,7 +465,7 @@ void MigrationDestinationManager::_migrateDriver(OperationContext* txn,
 
     invariant(initialState == READY);
 
-    ScopedDbConnection conn(fromShard);
+    ScopedDbConnection conn(fromShardConnString);
 
     // Just tests the connection
     conn->getLastError();
diff --git a/src/mongo/db/s/migration_destination_manager.h b/src/mongo/db/s/migration_destination_manager.h
index 4f928ab99fd..12e437f6ed4 100644
--- a/src/mongo/db/s/migration_destination_manager.h
+++ b/src/mongo/db/s/migration_destination_manager.h
@@ -34,7 +34,10 @@
 #include "mongo/bson/bsonobj.h"
 #include "mongo/bson/bsonobjbuilder.h"
 #include "mongo/bson/oid.h"
+#include "mongo/client/connection_string.h"
+#include "mongo/db/namespace_string.h"
 #include "mongo/db/s/migration_session_id.h"
+#include "mongo/s/shard_id.h"
 #include "mongo/stdx/condition_variable.h"
 #include "mongo/stdx/mutex.h"
 #include "mongo/stdx/thread.h"
@@ -42,7 +45,6 @@
 
 namespace mongo {
 
-class NamespaceString;
 class OperationContext;
 class Status;
 struct WriteConcernOptions;
@@ -66,6 +68,9 @@ public:
     State getState() const;
     void setState(State newState);
 
+    /**
+     * Checks whether the MigrationDestinationManager is currently handling a migration.
+     */
     bool isActive() const;
 
     /**
@@ -74,11 +79,19 @@ public:
     void report(BSONObjBuilder& b);
 
     /**
+     * Returns a report on the active migration, if the migration is active. Otherwise return an
+     * empty BSONObj.
+     */
+    BSONObj getMigrationStatusReport();
+
+    /**
      * Returns OK if migration started successfully.
      */
     Status start(const std::string& ns,
                  const MigrationSessionId& sessionId,
-                 const std::string& fromShard,
+                 const ConnectionString& fromShardConnString,
+                 const ShardId& fromShard,
+                 const ShardId& toShard,
                  const BSONObj& min,
                  const BSONObj& max,
                  const BSONObj& shardKeyPattern,
@@ -98,7 +111,7 @@ private:
                         BSONObj min,
                         BSONObj max,
                         BSONObj shardKeyPattern,
-                        std::string fromShard,
+                        ConnectionString fromShardConnString,
                         OID epoch,
                         WriteConcernOptions writeConcern);
 
@@ -108,7 +121,7 @@ private:
                         const BSONObj& min,
                         const BSONObj& max,
                         const BSONObj& shardKeyPattern,
-                        const std::string& fromShard,
+                        const ConnectionString& fromShardConnString,
                         const OID& epoch,
                         const WriteConcernOptions& writeConcern);
 
@@ -159,6 +172,14 @@ private:
                           const BSONObj& max,
                           const OID& epoch);
 
+    /**
+     * Checks whether the MigrationDestinationManager is currently handling a migration by checking
+     * that the migration "_sessionId" is initialized.
+     *
+     * Expects the caller to have the class _mutex locked!
+     */
+    bool _isActive_inlock() const;
+
     // Mutex to guard all fields
     mutable stdx::mutex _mutex;
 
@@ -170,8 +191,10 @@ private:
 
     stdx::thread _migrateThreadHandle;
 
-    std::string _ns;
-    std::string _from;
+    NamespaceString _nss;
+    ConnectionString _fromShardConnString;
+    ShardId _fromShard;
+    ShardId _toShard;
 
     BSONObj _min;
     BSONObj _max;
diff --git a/src/mongo/db/s/migration_destination_manager_legacy_commands.cpp b/src/mongo/db/s/migration_destination_manager_legacy_commands.cpp
index 6c528147df9..dca0a9c43bd 100644
--- a/src/mongo/db/s/migration_destination_manager_legacy_commands.cpp
+++ b/src/mongo/db/s/migration_destination_manager_legacy_commands.cpp
@@ -126,10 +126,9 @@ public:
             }
         }
 
-        if (!cmdObj["toShardName"].eoo()) {
-            dassert(cmdObj["toShardName"].type() == String);
-            shardingState->setShardName(cmdObj["toShardName"].String());
-        }
+        const ShardId toShard(cmdObj["toShardName"].String());
+        shardingState->setShardName(toShard.toString());
+        const ShardId fromShard(cmdObj["fromShardName"].String());
 
         const string ns = cmdObj.firstElement().String();
 
@@ -158,20 +157,30 @@ public:
 
         BSONObj shardKeyPattern = cmdObj["shardKeyPattern"].Obj().getOwned();
 
-        const string fromShard(cmdObj["from"].String());
+        auto statusWithFromShardConnectionString = ConnectionString::parse(cmdObj["from"].String());
+        if (!statusWithFromShardConnectionString.isOK()) {
+            errmsg = str::stream() << "cannot start recv'ing chunk "
+                                   << "[" << min << "," << max << ")"
+                                   << causedBy(statusWithFromShardConnectionString.getStatus());
+
+            warning() << errmsg;
+            return false;
+        }
 
         const MigrationSessionId migrationSessionId(
             uassertStatusOK(MigrationSessionId::extractFromBSON(cmdObj)));
 
-        Status startStatus =
-            shardingState->migrationDestinationManager()->start(ns,
-                                                                migrationSessionId,
-                                                                fromShard,
-                                                                min,
-                                                                max,
-                                                                shardKeyPattern,
-                                                                currentVersion.epoch(),
-                                                                writeConcern);
+        Status startStatus = shardingState->migrationDestinationManager()->start(
+            ns,
+            migrationSessionId,
+            statusWithFromShardConnectionString.getValue(),
+            fromShard,
+            toShard,
+            min,
+            max,
+            shardKeyPattern,
+            currentVersion.epoch(),
+            writeConcern);
         if (!startStatus.isOK()) {
             return appendCommandStatus(result, startStatus);
         }
diff --git a/src/mongo/db/s/migration_source_manager.cpp b/src/mongo/db/s/migration_source_manager.cpp
index 3ee4660a932..f1bb4701e34 100644
--- a/src/mongo/db/s/migration_source_manager.cpp
+++ b/src/mongo/db/s/migration_source_manager.cpp
@@ -38,6 +38,7 @@
 #include "mongo/db/s/collection_metadata.h"
 #include "mongo/db/s/collection_sharding_state.h"
 #include "mongo/db/s/migration_chunk_cloner_source_legacy.h"
+#include "mongo/db/s/migration_util.h"
 #include "mongo/db/s/operation_sharding_state.h"
 #include "mongo/db/s/sharding_state.h"
 #include "mongo/db/s/sharding_state_recovery.h"
@@ -533,4 +534,13 @@ void MigrationSourceManager::_cleanup(OperationContext* txn) {
     _state = kDone;
 }
 
+BSONObj MigrationSourceManager::getMigrationStatusReport() const {
+    return migrationutil::makeMigrationStatusDocument(_args.getNss(),
+                                                      _args.getFromShardId(),
+                                                      _args.getToShardId(),
+                                                      true,
+                                                      _args.getMinKey(),
+                                                      _args.getMaxKey());
+}
+
 }  // namespace mongo
diff --git a/src/mongo/db/s/migration_source_manager.h b/src/mongo/db/s/migration_source_manager.h
index a5f1260c098..99ce842cdbd 100644
--- a/src/mongo/db/s/migration_source_manager.h
+++ b/src/mongo/db/s/migration_source_manager.h
@@ -172,6 +172,13 @@ public:
         return _critSecSignal;
     }
 
+    /**
+     * Returns a report on the active migration.
+     *
+     * Must be called with some form of lock on the collection namespace.
+     */
+    BSONObj getMigrationStatusReport() const;
+
 private:
     // Used to track the current state of the source manager. See the methods above, which have
     // comments explaining the various state transitions.
diff --git a/src/mongo/db/s/migration_util.cpp b/src/mongo/db/s/migration_util.cpp
new file mode 100644
index 00000000000..0eccd40f3db
--- /dev/null
+++ b/src/mongo/db/s/migration_util.cpp
@@ -0,0 +1,65 @@
+/**
+ *    Copyright (C) 2016 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/s/migration_util.h"
+
+#include "mongo/bson/bsonobj.h"
+#include "mongo/bson/bsonobjbuilder.h"
+#include "mongo/db/namespace_string.h"
+#include "mongo/s/catalog/type_chunk.h"
+
+namespace mongo {
+namespace migrationutil {
+namespace {
+
+const char kSourceShard[] = "source";
+const char kDestinationShard[] = "destination";
+const char kIsDonorShard[] = "isDonorShard";
+const char kChunk[] = "chunk";
+const char kCollection[] = "collection";
+}
+
+BSONObj makeMigrationStatusDocument(const NamespaceString& nss,
+                                    const ShardId& fromShard,
+                                    const ShardId& toShard,
+                                    const bool& isDonorShard,
+                                    const BSONObj& min,
+                                    const BSONObj& max) {
+    BSONObjBuilder builder;
+    builder.append(kSourceShard, fromShard.toString());
+    builder.append(kDestinationShard, toShard.toString());
+    builder.append(kIsDonorShard, isDonorShard);
+    builder.append(kChunk, BSON(ChunkType::min(min) << ChunkType::max(max)));
+    builder.append(kCollection, nss.ns());
+    return builder.obj();
+}
+
+}  // namespace migrationutil
+}  // namespace mongo
diff --git a/src/mongo/db/s/migration_util.h b/src/mongo/db/s/migration_util.h
new file mode 100644
index 00000000000..20369bab790
--- /dev/null
+++ b/src/mongo/db/s/migration_util.h
@@ -0,0 +1,60 @@
+/**
+ *    Copyright (C) 2016 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+namespace mongo {
+
+class BSONObj;
+class NamespaceString;
+class ShardId;
+
+namespace migrationutil {
+
+/**
+ * Creates a report document with the provided parameters:
+ *
+ * {
+ *     source:          "shard0000"
+ *     destination:     "shard0001"
+ *     isDonorShard:    true or false
+ *     chunk:           {"min": <MinKey>, "max": <MaxKey>}
+ *     collection:      "dbName.collName"
+ * }
+ *
+ */
+BSONObj makeMigrationStatusDocument(const NamespaceString& nss,
+                                    const ShardId& fromShard,
+                                    const ShardId& toShard,
+                                    const bool& isDonorShard,
+                                    const BSONObj& min,
+                                    const BSONObj& max);
+
+}  // namespace shardutil
+
+}  // namespace mongo
diff --git a/src/mongo/db/s/sharding_server_status.cpp b/src/mongo/db/s/sharding_server_status.cpp
index 4cb8c4f047e..8f58e24600b 100644
--- a/src/mongo/db/s/sharding_server_status.cpp
+++ b/src/mongo/db/s/sharding_server_status.cpp
@@ -55,6 +55,14 @@ public:
                           shardingState->getConfigServer(txn).toString());
 
             Grid::get(txn)->configOpTime().append(&result, "lastSeenConfigServerOpTime");
+
+            // Get a migration status report if a migration is active for which this is the source
+            // shard. ShardingState::getActiveMigrationStatusReport will take an IS lock on the
+            // namespace of the active migration if there is one that is active.
+            BSONObj migrationStatus = ShardingState::get(txn)->getActiveMigrationStatusReport(txn);
+            if (!migrationStatus.isEmpty()) {
+                result.append("migrations", migrationStatus);
+            }
         }
 
         return result.obj();
diff --git a/src/mongo/db/s/sharding_state.cpp b/src/mongo/db/s/sharding_state.cpp
index d5e57b8357d..16898c65b21 100644
--- a/src/mongo/db/s/sharding_state.cpp
+++ b/src/mongo/db/s/sharding_state.cpp
@@ -751,6 +751,10 @@ boost::optional<NamespaceString> ShardingState::getActiveMigrationNss() {
     return _activeMigrationsRegistry.getActiveMigrationNss();
 }
 
+BSONObj ShardingState::getActiveMigrationStatusReport(OperationContext* txn) {
+    return _activeMigrationsRegistry.getActiveMigrationStatusReport(txn);
+}
+
 void ShardingState::appendInfo(OperationContext* txn, BSONObjBuilder& builder) {
     const bool isEnabled = enabled();
     builder.appendBool("enabled", isEnabled);
diff --git a/src/mongo/db/s/sharding_state.h b/src/mongo/db/s/sharding_state.h
index 28eb837c215..66711e4d29f 100644
--- a/src/mongo/db/s/sharding_state.h
+++ b/src/mongo/db/s/sharding_state.h
@@ -228,6 +228,14 @@ public:
     boost::optional<NamespaceString> getActiveMigrationNss();
 
     /**
+     * Get a migration status report from the migration registry. If no migration is active, this
+     * returns an empty BSONObj.
+     *
+     * Takes an IS lock on the namespace of the active migration, if one is active.
+     */
+    BSONObj getActiveMigrationStatusReport(OperationContext* txn);
+
+    /**
      * For testing only. Mock the initialization method used by initializeFromConfigConnString and
      * initializeFromShardIdentity after all checks are performed.
      */
diff --git a/src/mongo/db/s/start_chunk_clone_request.cpp b/src/mongo/db/s/start_chunk_clone_request.cpp
index 9aa27ba5fc9..757a818f66f 100644
--- a/src/mongo/db/s/start_chunk_clone_request.cpp
+++ b/src/mongo/db/s/start_chunk_clone_request.cpp
@@ -33,7 +33,6 @@
 #include "mongo/base/status_with.h"
 #include "mongo/bson/bsonobjbuilder.h"
 #include "mongo/bson/util/bson_extract.h"
-#include "mongo/s/shard_id.h"
 
 namespace mongo {
 namespace {
@@ -41,6 +40,7 @@ namespace {
 const char kRecvChunkStart[] = "_recvChunkStart";
 const char kConfigServerConnectionString[] = "configdb";
 const char kFromShardConnectionString[] = "from";
+const char kFromShardId[] = "fromShardName";
 const char kToShardId[] = "toShardName";
 const char kChunkMinKey[] = "min";
 const char kChunkMaxKey[] = "max";
@@ -104,7 +104,18 @@ StatusWith<StartChunkCloneRequest> StartChunkCloneRequest::createFromCommand(Nam
     }
 
     {
-        Status status = bsonExtractStringField(obj, kToShardId, &request._toShardId);
+        std::string fromShard;
+        Status status = bsonExtractStringField(obj, kFromShardId, &fromShard);
+        request._fromShardId = fromShard;
+        if (!status.isOK()) {
+            return status;
+        }
+    }
+
+    {
+        std::string toShard;
+        Status status = bsonExtractStringField(obj, kToShardId, &toShard);
+        request._toShardId = toShard;
         if (!status.isOK()) {
             return status;
         }
@@ -161,6 +172,7 @@ void StartChunkCloneRequest::appendAsCommand(
     const MigrationSessionId& sessionId,
     const ConnectionString& configServerConnectionString,
     const ConnectionString& fromShardConnectionString,
+    const ShardId& fromShardId,
     const ShardId& toShardId,
     const BSONObj& chunkMinKey,
     const BSONObj& chunkMaxKey,
@@ -174,6 +186,7 @@ void StartChunkCloneRequest::appendAsCommand(
     sessionId.append(builder);
     builder->append(kConfigServerConnectionString, configServerConnectionString.toString());
     builder->append(kFromShardConnectionString, fromShardConnectionString.toString());
+    builder->append(kFromShardId, fromShardId.toString());
     builder->append(kToShardId, toShardId.toString());
     builder->append(kChunkMinKey, chunkMinKey);
     builder->append(kChunkMaxKey, chunkMaxKey);
diff --git a/src/mongo/db/s/start_chunk_clone_request.h b/src/mongo/db/s/start_chunk_clone_request.h
index 8a7b43d5f27..12533f287f6 100644
--- a/src/mongo/db/s/start_chunk_clone_request.h
+++ b/src/mongo/db/s/start_chunk_clone_request.h
@@ -34,13 +34,14 @@
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/s/migration_session_id.h"
 #include "mongo/s/migration_secondary_throttle_options.h"
+#include "mongo/s/shard_id.h"
 
 namespace mongo {
 
 class BSONObjBuilder;
 template <typename T>
 class StatusWith;
-class ShardId;
+
 /**
  * Parses the arguments for a start chunk clone operation.
  */
@@ -62,6 +63,7 @@ public:
                                 const MigrationSessionId& sessionId,
                                 const ConnectionString& configServerConnectionString,
                                 const ConnectionString& fromShardConnectionString,
+                                const ShardId& fromShardId,
                                 const ShardId& toShardId,
                                 const BSONObj& chunkMinKey,
                                 const BSONObj& chunkMaxKey,
@@ -84,7 +86,11 @@ public:
         return _fromShardCS;
     }
 
-    const std::string& getToShardId() const {
+    const ShardId& getFromShardId() const {
+        return _fromShardId;
+    }
+
+    const ShardId& getToShardId() const {
         return _toShardId;
     }
 
@@ -123,8 +129,9 @@ private:
     // The source host and port
     ConnectionString _fromShardCS;
 
-    // The recipient shard id
-    std::string _toShardId;
+    // The recipient and destination shard IDs.
+    ShardId _fromShardId;
+    ShardId _toShardId;
 
     // Exact min and max key of the chunk being moved
     BSONObj _minKey;
diff --git a/src/mongo/db/s/start_chunk_clone_request_test.cpp b/src/mongo/db/s/start_chunk_clone_request_test.cpp
index 342d49d9130..92b797ec9cd 100644
--- a/src/mongo/db/s/start_chunk_clone_request_test.cpp
+++ b/src/mongo/db/s/start_chunk_clone_request_test.cpp
@@ -52,6 +52,7 @@ TEST(StartChunkCloneRequest, CreateAsCommandComplete) {
         sessionId,
         assertGet(ConnectionString::parse("TestConfigRS/CS1:12345,CS2:12345,CS3:12345")),
         assertGet(ConnectionString::parse("TestDonorRS/Donor1:12345,Donor2:12345,Donor3:12345")),
+        ShardId("shard0001"),
         ShardId("shard0002"),
         BSON("Key" << -100),
         BSON("Key" << 100),
@@ -62,6 +63,7 @@ TEST(StartChunkCloneRequest, CreateAsCommandComplete) {
 
     auto request = assertGet(StartChunkCloneRequest::createFromCommand(
         NamespaceString(cmdObj["_recvChunkStart"].String()), cmdObj));
+
     ASSERT_EQ("TestDB.TestColl", request.getNss().ns());
     ASSERT_EQ(sessionId.toString(), request.getSessionId().toString());
     ASSERT(sessionId.matches(request.getSessionId()));
@@ -70,7 +72,8 @@ TEST(StartChunkCloneRequest, CreateAsCommandComplete) {
         assertGet(ConnectionString::parse("TestDonorRS/Donor1:12345,Donor2:12345,Donor3:12345"))
             .toString(),
         request.getFromShardConnectionString().toString());
-    ASSERT_EQ("shard0002", request.getToShardId());
+    ASSERT_EQ("shard0001", request.getFromShardId().toString());
+    ASSERT_EQ("shard0002", request.getToShardId().toString());
     ASSERT_BSONOBJ_EQ(BSON("Key" << -100), request.getMinKey());
     ASSERT_BSONOBJ_EQ(BSON("Key" << 100), request.getMaxKey());
     ASSERT_BSONOBJ_EQ(BSON("Key" << 1), request.getShardKeyPattern());