SERVER-37384 lock db prior to examining UUID catalog, to avoid phantom NamespaceNotFound errors

2 files changed, 7 insertions, 15 deletions

diff --git a/src/mongo/db/catalog_raii.cpp b/src/mongo/db/catalog_raii.cpp
index 339a72655ce..79e4e8e10d4 100644
--- a/src/mongo/db/catalog_raii.cpp
+++ b/src/mongo/db/catalog_raii.cpp
@@ -68,19 +68,11 @@ AutoGetCollection::AutoGetCollection(OperationContext* opCtx,
                                      LockMode modeColl,
                                      ViewMode viewMode,
                                      Date_t deadline)
-    :  // The UUID to NamespaceString resolution is performed outside of any locks
-      _resolvedNss(resolveNamespaceStringOrUUID(opCtx, nsOrUUID)),
-      // The database locking is performed based on the resolved NamespaceString
-      _autoDb(opCtx, _resolvedNss.db(), modeDB, deadline) {
-    // In order to account for possible collection rename happening because the resolution from UUID
-    // to NamespaceString was done outside of database lock, if UUID was specified we need to
-    // re-resolve the _resolvedNss after acquiring the database lock so it has the correct value.
-    //
-    // Holding a database lock prevents collection renames, so this guarantees a stable UUID to
-    // NamespaceString mapping.
-    if (nsOrUUID.uuid())
-        _resolvedNss = resolveNamespaceStringOrUUID(opCtx, nsOrUUID);
-
+    : _autoDb(opCtx,
+              !nsOrUUID.dbname().empty() ? nsOrUUID.dbname() : nsOrUUID.nss()->db(),
+              modeDB,
+              deadline),
+      _resolvedNss(resolveNamespaceStringOrUUID(opCtx, nsOrUUID)) {
     _collLock.emplace(opCtx->lockState(), _resolvedNss.ns(), modeColl, deadline);
     uassertLockTimeout(
         str::stream() << "collection " << nsOrUUID.toString(), modeColl, _collLock->isLocked());
diff --git a/src/mongo/db/catalog_raii.h b/src/mongo/db/catalog_raii.h
index 2f2ff984f4f..4bb0a610c44 100644
--- a/src/mongo/db/catalog_raii.h
+++ b/src/mongo/db/catalog_raii.h
@@ -138,12 +138,12 @@ public:
     }
 
 private:
+    AutoGetDb _autoDb;
+
     // If the object was instantiated with a UUID, contains the resolved namespace, otherwise it is
     // the same as the input namespace string
     NamespaceString _resolvedNss;
 
-    AutoGetDb _autoDb;
-
     // This field is boost::optional, because in the case of lookup by UUID, the collection lock
     // might need to be relocked for the correct namespace
     boost::optional<Lock::CollectionLock> _collLock;