SERVER-25916: disable doc validation for all writes during bulk collection cloning in initial sync.

jstests/replsets/initial_sync_document_validation.js

@@ -0,0 +1,30 @@
+/**
+ * Tests that initial sync via resync command does not fail if it inserts documents
+ * which don't validate.
+ */
+
+(function() {
+    var name = 'initial_sync_document_validation';
+    var replSet = new ReplSetTest({
+        name: name,
+        nodes: 2,
+    });
+
+    replSet.startSet();
+    replSet.initiate();
+    var primary = replSet.getPrimary();
+    var secondary = replSet.getSecondary();
+
+    var coll = primary.getDB('test').getCollection(name);
+    assert.writeOK(coll.insert({_id: 0, x: 1}));
+    assert.commandWorked(coll.runCommand("collMod", {"validator": {a: {$exists: true}}}));
+
+    assert.commandWorked(secondary.getDB("admin").runCommand({resync: 1}));
+    replSet.awaitReplication();
+    replSet.awaitSecondaryNodes();
+
+    assert.eq(1, secondary.getDB("test")[name].count());
+    assert.docEq({_id: 0, x: 1}, secondary.getDB("test")[name].findOne());
+
+    replSet.stopSet();
+})();

src/mongo/db/repl/storage_interface_impl.cpp

@@ -253,9 +253,10 @@ StorageInterfaceImpl::createCollectionForBulkLoading(
     std::unique_ptr<CollectionBulkLoader> loaderToReturn;
 
     auto status = runner->runSynchronousTask([&](OperationContext* txn) -> Status {
-        // We are not replicating nor validating these writes.
+        // We are not replicating nor validating writes under this OperationContext*.
+        // The OperationContext* is used for all writes to the (newly) cloned collection.
         txn->setReplicatedWrites(false);
-        DisableDocumentValidation validationDisabler(txn);
+        documentValidationDisabled(txn) = true;
 
         // Retry if WCE.
         MONGO_WRITE_CONFLICT_RETRY_LOOP_BEGIN {