SERVER-35881 Gate prepareTransaction on featureCompatibilityVersion 4.2

7 files changed, 66 insertions, 0 deletions

diff --git a/buildscripts/resmokeconfig/suites/replica_sets_initsync_jscore_passthrough.yml b/buildscripts/resmokeconfig/suites/replica_sets_initsync_jscore_passthrough.yml
index dba7fd9b567..5a4d1186c5a 100644
--- a/buildscripts/resmokeconfig/suites/replica_sets_initsync_jscore_passthrough.yml
+++ b/buildscripts/resmokeconfig/suites/replica_sets_initsync_jscore_passthrough.yml
@@ -78,6 +78,7 @@ selector:
   # entries.
   - jstests/core/txns/commit_prepared_transaction.js
   - jstests/core/txns/timestamped_reads_wait_for_prepare_oplog_visibility.js
+  - jstests/core/txns/prepare_requires_fcv42.js
 
 run_hook_interval: &run_hook_interval 20
 executor:
diff --git a/buildscripts/resmokeconfig/suites/replica_sets_initsync_static_jscore_passthrough.yml b/buildscripts/resmokeconfig/suites/replica_sets_initsync_static_jscore_passthrough.yml
index 4ececd471fd..556578ef569 100644
--- a/buildscripts/resmokeconfig/suites/replica_sets_initsync_static_jscore_passthrough.yml
+++ b/buildscripts/resmokeconfig/suites/replica_sets_initsync_static_jscore_passthrough.yml
@@ -15,6 +15,7 @@ selector:
   # entries.
   - jstests/core/txns/commit_prepared_transaction.js
   - jstests/core/txns/timestamped_reads_wait_for_prepare_oplog_visibility.js
+  - jstests/core/txns/prepare_requires_fcv42.js
 
 run_hook_interval: &run_hook_interval 20
 executor:
diff --git a/buildscripts/resmokeconfig/suites/replica_sets_jscore_passthrough.yml b/buildscripts/resmokeconfig/suites/replica_sets_jscore_passthrough.yml
index 40a40434b62..70d68273f79 100644
--- a/buildscripts/resmokeconfig/suites/replica_sets_jscore_passthrough.yml
+++ b/buildscripts/resmokeconfig/suites/replica_sets_jscore_passthrough.yml
@@ -27,6 +27,7 @@ selector:
   # entries.
   - jstests/core/txns/commit_prepared_transaction.js
   - jstests/core/txns/timestamped_reads_wait_for_prepare_oplog_visibility.js
+  - jstests/core/txns/prepare_requires_fcv42.js
 
 executor:
   archive:
diff --git a/buildscripts/resmokeconfig/suites/replica_sets_kill_secondaries_jscore_passthrough.yml b/buildscripts/resmokeconfig/suites/replica_sets_kill_secondaries_jscore_passthrough.yml
index 3e26a655d41..a7a72179829 100644
--- a/buildscripts/resmokeconfig/suites/replica_sets_kill_secondaries_jscore_passthrough.yml
+++ b/buildscripts/resmokeconfig/suites/replica_sets_kill_secondaries_jscore_passthrough.yml
@@ -18,6 +18,7 @@ selector:
   # entries.
   - jstests/core/txns/commit_prepared_transaction.js
   - jstests/core/txns/timestamped_reads_wait_for_prepare_oplog_visibility.js
+  - jstests/core/txns/prepare_requires_fcv42.js
 
 executor:
   archive:
diff --git a/buildscripts/resmokeconfig/suites/sharded_core_txns.yml b/buildscripts/resmokeconfig/suites/sharded_core_txns.yml
index 7f37c9c1c28..c2188ce6cff 100644
--- a/buildscripts/resmokeconfig/suites/sharded_core_txns.yml
+++ b/buildscripts/resmokeconfig/suites/sharded_core_txns.yml
@@ -23,6 +23,7 @@ selector:
   - jstests/core/txns/prepare_committed_transaction.js
   - jstests/core/txns/prepare_conflict.js
   - jstests/core/txns/timestamped_reads_wait_for_prepare_oplog_visibility.js
+  - jstests/core/txns/prepare_requires_fcv42.js
 
   # Mongos doesn't upconvert from local or majority level readConcern to snapshot.
   - jstests/core/txns/upconvert_read_concern.js
diff --git a/jstests/core/txns/prepare_requires_fcv42.js b/jstests/core/txns/prepare_requires_fcv42.js
new file mode 100644
index 00000000000..35905e5116e
--- /dev/null
+++ b/jstests/core/txns/prepare_requires_fcv42.js
@@ -0,0 +1,56 @@
+/**
+ * Tests that 'prepareTransaction' only succeeds in FCV 4.2.
+ *
+ * @tags: [uses_transactions]
+ */
+(function() {
+    "use strict";
+    load("jstests/libs/feature_compatibility_version.js");
+    load("jstests/core/txns/libs/prepare_helpers.js");
+
+    const dbName = "test";
+    const collName = "prepare_requires_fcv42";
+    const testDB = db.getSiblingDB(dbName);
+    const adminDB = db.getSiblingDB('admin');
+
+    testDB[collName].drop({writeConcern: {w: "majority"}});
+    assert.commandWorked(testDB.runCommand({create: collName, writeConcern: {w: "majority"}}));
+
+    const sessionOptions = {causalConsistency: false};
+    const session = testDB.getMongo().startSession(sessionOptions);
+    const sessionDB = session.getDatabase(dbName);
+
+    try {
+        jsTestLog("Transaction succeeds in latest FCV.");
+        checkFCV(adminDB, latestFCV);
+        session.startTransaction();
+        assert.commandWorked(sessionDB[collName].insert({_id: "a"}));
+        let prepareTimestamp = PrepareHelpers.prepareTransaction(session);
+        assert.commandWorked(PrepareHelpers.commitTransaction(session, prepareTimestamp));
+
+        jsTestLog("Downgrade the featureCompatibilityVersion.");
+        assert.commandWorked(testDB.adminCommand({setFeatureCompatibilityVersion: lastStableFCV}));
+        checkFCV(adminDB, lastStableFCV);
+
+        jsTestLog("Transaction fails to prepare in last stable FCV.");
+        session.startTransaction();
+        assert.commandWorked(sessionDB[collName].insert({_id: "b"}));
+        assert.commandFailedWithCode(sessionDB.adminCommand({prepareTransaction: 1}),
+                                     ErrorCodes.CommandNotSupported);
+        // Abort the transaction in the shell.
+        session.abortTransaction();
+
+    } finally {
+        jsTestLog("Restore the original featureCompatibilityVersion.");
+        assert.commandWorked(testDB.adminCommand({setFeatureCompatibilityVersion: latestFCV}));
+        checkFCV(adminDB, latestFCV);
+    }
+
+    jsTestLog("Transaction succeeds in latest FCV after upgrade.");
+    session.startTransaction();
+    assert.commandWorked(sessionDB[collName].insert({_id: "c"}));
+    let prepareTimestamp = PrepareHelpers.prepareTransaction(session);
+    assert.commandWorked(PrepareHelpers.commitTransaction(session, prepareTimestamp));
+
+    session.endSession();
+}());
diff --git a/src/mongo/db/s/txn_two_phase_commit_cmds.cpp b/src/mongo/db/s/txn_two_phase_commit_cmds.cpp
index cd5c0a1c099..99ed8e1ae5a 100644
--- a/src/mongo/db/s/txn_two_phase_commit_cmds.cpp
+++ b/src/mongo/db/s/txn_two_phase_commit_cmds.cpp
@@ -73,6 +73,11 @@ public:
                 "prepareTransaction must be run within a transaction",
                 txnParticipant);
 
+        uassert(ErrorCodes::CommandNotSupported,
+                "'prepareTransaction' is only supported in feature compatibility version 4.2",
+                (serverGlobalParams.featureCompatibility.getVersion() ==
+                 ServerGlobalParams::FeatureCompatibility::Version::kFullyUpgradedTo42));
+
         uassert(ErrorCodes::NoSuchTransaction,
                 "Transaction isn't in progress",
                 txnParticipant->inMultiDocumentTransaction());