SERVER-35253 Fix dbHash cmd to acquire IX locks inside multi-stmt txn.

(cherry picked from commit 52976ef70f1fa991c9b30ba5e0e45fb8e2a1a1d8)
(cherry picked from commit 1b3963a81c6cf68519b9ef5e798cf997483cc7b3)

1 files changed, 14 insertions, 9 deletions

diff --git a/src/mongo/db/commands/dbhash.cpp b/src/mongo/db/commands/dbhash.cpp
index 42375adb09f..1a9b1ca3678 100644
--- a/src/mongo/db/commands/dbhash.cpp
+++ b/src/mongo/db/commands/dbhash.cpp
@@ -45,6 +45,7 @@
 #include "mongo/db/exec/working_set_common.h"
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/query/internal_plans.h"
+#include "mongo/db/session_catalog.h"
 #include "mongo/stdx/mutex.h"
 #include "mongo/util/log.h"
 #include "mongo/util/md5.hpp"
@@ -114,10 +115,11 @@ public:
         // We lock the entire database in S-mode in order to ensure that the contents will not
         // change for the snapshot.
         auto lockMode = LockMode::MODE_S;
-        if (repl::ReadConcernArgs::get(opCtx).getArgsAtClusterTime()) {
-            // However, if we are using "atClusterTime" to read from a consistent snapshot, then we
-            // only need to lock the database in intent mode to ensure that none of the collections
-            // get dropped.
+        auto* session = OperationContextSession::get(opCtx);
+        if (session && session->inSnapshotReadOrMultiDocumentTransaction()) {
+            // However, if we are inside a multi-statement transaction or using snapshot reads to
+            // read from a consistent snapshot, then we only need to lock the database in intent
+            // mode to ensure that none of the collections get dropped.
             lockMode = getLockModeForQuery(opCtx);
         }
         AutoGetDb autoDb(opCtx, ns, lockMode);
@@ -217,11 +219,14 @@ private:
             return "";
 
         boost::optional<Lock::CollectionLock> collLock;
-        if (repl::ReadConcernArgs::get(opCtx).getArgsAtClusterTime()) {
-            // When using "atClusterTime", we are only holding the database lock in intent mode. We
-            // need to also acquire the collection lock in intent mode to ensure reading from the
-            // consistent snapshot doesn't overlap with any catalog operations on the collection.
-            invariant(opCtx->lockState()->isDbLockedForMode(db->name(), MODE_IS));
+        auto* session = OperationContextSession::get(opCtx);
+        if (session && session->inSnapshotReadOrMultiDocumentTransaction()) {
+            // When inside a multi-statement transaction or using snapshot reads, we are only
+            // holding the database lock in intent mode. We need to also acquire the collection lock
+            // in intent mode to ensure reading from the consistent snapshot doesn't overlap with
+            // any catalog operations on the collection.
+            invariant(
+                opCtx->lockState()->isDbLockedForMode(db->name(), getLockModeForQuery(opCtx)));
             collLock.emplace(opCtx->lockState(), fullCollectionName, getLockModeForQuery(opCtx));
 
             auto minSnapshot = collection->getMinimumVisibleSnapshot();