SERVER-37313 Secondary foreground index build should take Database X rather than Global X lock

(cherry picked from commit e7bed9bdcb376d5a06dce6228047309e8481f9cf)

2 files changed, 13 insertions, 5 deletions

diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index 2ad84d776e9..94477d111d8 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -231,6 +231,11 @@ void createIndexForApplyOps(OperationContext* opCtx,
                             const NamespaceString& indexNss,
                             IncrementOpsAppliedStatsFn incrementOpsAppliedStats,
                             OplogApplication::Mode mode) {
+    // Lock the database if it's not locked.
+    boost::optional<Lock::DBLock> dbLock;
+    if (!opCtx->lockState()->isDbLockedForMode(indexNss.db(), MODE_X)) {
+        dbLock.emplace(opCtx, indexNss.db(), MODE_X);
+    }
     // Check if collection exists.
     Database* db = DatabaseHolder::getDatabaseHolder().get(opCtx, indexNss.ns());
     auto indexCollection = db ? db->getCollection(opCtx, indexNss) : nullptr;
@@ -1525,6 +1530,7 @@ Status applyCommand_inlock(OperationContext* opCtx,
         return {ErrorCodes::InvalidNamespace, "invalid ns: " + std::string(nss.ns())};
     }
     {
+        Lock::DBLock lock(opCtx, nss.db(), MODE_IS);
         Database* db = DatabaseHolder::getDatabaseHolder().get(opCtx, nss.ns());
         if (db && !db->getCollection(opCtx, nss) && db->getViewCatalog()->lookup(opCtx, nss.ns())) {
             return {ErrorCodes::CommandNotSupportedOnView,
@@ -1549,10 +1555,6 @@ Status applyCommand_inlock(OperationContext* opCtx,
                                     << redact(op));
     }
 
-    // Applying commands in repl is done under Global W-lock, so it is safe to not
-    // perform the current DB checks after reacquiring the lock.
-    invariant(opCtx->lockState()->isW());
-
     // Parse optime from oplog entry unless we are applying this command in standalone or on a
     // primary (replicated writes enabled).
     OpTime opTime;
diff --git a/src/mongo/db/repl/sync_tail.cpp b/src/mongo/db/repl/sync_tail.cpp
index 0356a80e1d9..b611f8b8305 100644
--- a/src/mongo/db/repl/sync_tail.cpp
+++ b/src/mongo/db/repl/sync_tail.cpp
@@ -387,7 +387,13 @@ Status SyncTail::syncApply(OperationContext* opCtx,
         return writeConflictRetry(opCtx, "syncApply_command", nss.ns(), [&] {
             // a command may need a global write lock. so we will conservatively go
             // ahead and grab one here. suboptimal. :-(
-            Lock::GlobalWrite globalWriteLock(opCtx);
+            boost::optional<Lock::GlobalWrite> globalWriteLock;
+
+            const StringData commandName(op["o"].embeddedObject().firstElementFieldName());
+            // SERVER-37313: createIndex does not need to take the Global X lock.
+            if (commandName != "createIndexes") {
+                globalWriteLock.emplace(opCtx);
+            }
 
             // special case apply for commands to avoid implicit database creation
             Status status = applyCommand_inlock(opCtx, op, oplogApplicationMode);