From 979ecf1842bb431badd5ad6b6025ac257742c684 Mon Sep 17 00:00:00 2001
From: Pierlauro Sciarelli <pierlauro.sciarelli@mongodb.com>
Date: Fri, 27 Aug 2021 12:48:56 +0000
Subject: SERVER-59500 DDL coordinators must not release dist locks on stepdown

---
 src/mongo/db/s/dist_lock_manager.h          |  4 ++++
 src/mongo/db/s/sharding_ddl_coordinator.cpp | 32 ++++++++++++++++++++++-------
 src/mongo/db/s/sharding_ddl_coordinator.h   |  2 +-
 3 files changed, 30 insertions(+), 8 deletions(-)

(limited to 'src/mongo/db')

diff --git a/src/mongo/db/s/dist_lock_manager.h b/src/mongo/db/s/dist_lock_manager.h
index dfd0270732e..556cdbd8788 100644
--- a/src/mongo/db/s/dist_lock_manager.h
+++ b/src/mongo/db/s/dist_lock_manager.h
@@ -76,6 +76,10 @@ public:
 
         ScopedLock(ScopedLock&& other);
 
+        const StringData getNs() {
+            return _ns;
+        }
+
     private:
         std::string _ns;
         DistLockManager* _lockManager;
diff --git a/src/mongo/db/s/sharding_ddl_coordinator.cpp b/src/mongo/db/s/sharding_ddl_coordinator.cpp
index 7285f42d37b..87c4fd2cb34 100644
--- a/src/mongo/db/s/sharding_ddl_coordinator.cpp
+++ b/src/mongo/db/s/sharding_ddl_coordinator.cpp
@@ -117,9 +117,13 @@ ExecutorFuture<void> ShardingDDLCoordinator::_acquireLockAsync(
                auto distLockManager = DistLockManager::get(opCtx);
 
                const auto coorName = DDLCoordinatorType_serializer(_coordId.getOperationType());
-               auto distLock = uassertStatusOK(distLockManager->lock(
+
+               auto distLock = distLockManager->lockDirectLocally(
+                   opCtx, resource, DistLockManager::kDefaultLockTimeout);
+               _scopedLocks.emplace(std::move(distLock));
+
+               uassertStatusOK(distLockManager->lockDirect(
                    opCtx, resource, coorName, DistLockManager::kDefaultLockTimeout));
-               _scopedLocks.emplace(distLock.moveToAnotherThread());
            })
         .until([this](Status status) { return (!_recoveredFromDisk) || status.isOK(); })
         .withBackoffBetweenIterations(kExponentialBackoff)
@@ -237,10 +241,12 @@ SemiFuture<void> ShardingDDLCoordinator::run(std::shared_ptr<executor::ScopedTas
 
             auto completionStatus = status;
 
-            // Release the coordinator only if we are not stepping down
-            if ((!status.isA<ErrorCategory::NotPrimaryError>() &&
-                 !status.isA<ErrorCategory::ShutdownError>()) ||
-                (!status.isOK() && _completeOnError)) {
+            bool isSteppingDown = status.isA<ErrorCategory::NotPrimaryError>() ||
+                status.isA<ErrorCategory::ShutdownError>();
+
+            // Release the coordinator only in case the node is not stepping down or in case of
+            // acceptable error
+            if (!isSteppingDown || (!status.isOK() && _completeOnError)) {
                 try {
                     LOGV2(5565601,
                           "Releasing sharding DDL coordinator",
@@ -271,8 +277,20 @@ SemiFuture<void> ShardingDDLCoordinator::run(std::shared_ptr<executor::ScopedTas
                 }
             }
 
+            if (isSteppingDown) {
+                LOGV2(5950000,
+                      "Not releasing distributed locks because the node is stepping down or "
+                      "shutting down",
+                      "coordinatorId"_attr = _coordId,
+                      "status"_attr = status);
+            }
+
             while (!_scopedLocks.empty()) {
-                _scopedLocks.top().assignNewOpCtx(opCtx);
+                if (!isSteppingDown) {
+                    // (SERVER-59500) Only release the remote locks in case of no stepdown/shutdown
+                    const auto& resource = _scopedLocks.top().getNs();
+                    DistLockManager::get(opCtx)->unlock(opCtx, resource);
+                }
                 _scopedLocks.pop();
             }
 
diff --git a/src/mongo/db/s/sharding_ddl_coordinator.h b/src/mongo/db/s/sharding_ddl_coordinator.h
index 5077161911e..a3d9fc342a8 100644
--- a/src/mongo/db/s/sharding_ddl_coordinator.h
+++ b/src/mongo/db/s/sharding_ddl_coordinator.h
@@ -200,7 +200,7 @@ private:
     SharedPromise<void> _constructionCompletionPromise;
     SharedPromise<void> _completionPromise;
 
-    std::stack<DistLockManager::ScopedDistLock> _scopedLocks;
+    std::stack<DistLockManager::ScopedLock> _scopedLocks;
 };
 
 class ShardingDDLCoordinator_NORESILIENT {
-- 
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