SERVER-68511 MovePrimary update of config.databases entry must use dotted fields notation (backport v5.0)

2 files changed, 115 insertions, 28 deletions

diff --git a/jstests/multiVersion/genericSetFCVUsage/move_primary_setFCV.js b/jstests/multiVersion/genericSetFCVUsage/move_primary_setFCV.js
new file mode 100644
index 00000000000..c167603a0b3
--- /dev/null
+++ b/jstests/multiVersion/genericSetFCVUsage/move_primary_setFCV.js
@@ -0,0 +1,64 @@
+
+/**
+ * Test that `movePrimary` works for databases created under a different FCV
+ */
+(function() {
+
+"use strict";
+
+let st = new ShardingTest({shards: 2, mongos: 1, rs: {nodes: 1}});
+
+const mongos = st.s;
+const kBeforeDowngradingDbName = 'createdBeforeDowngrading';
+const kBeforeUpgradingDbName = 'createdBeforeUpgrading';
+const shard0 = st.shard0.shardName;
+const shard1 = st.shard1.shardName;
+
+const createdBeforeDowngradingDB = mongos.getDB(kBeforeDowngradingDbName);
+const createdBeforeUpgradingDB = mongos.getDB(kBeforeUpgradingDbName);
+
+function testMovePrimary(db) {
+    const dbName = db.getName();
+    const currentPrimary = mongos.getDB('config').databases.findOne({_id: dbName}).primary;
+    const newPrimary = currentPrimary == shard0 ? shard1 : shard0;
+    assert.eq(db.coll.countDocuments({}), 1);
+    assert.commandWorked(mongos.adminCommand({movePrimary: dbName, to: newPrimary}));
+    assert.eq(newPrimary, mongos.getDB('config').databases.findOne({_id: dbName}).primary);
+    assert.eq(db.coll.countDocuments({}), 1);
+}
+
+// Latest FCV
+assert.commandWorked(mongos.adminCommand({setFeatureCompatibilityVersion: latestFCV}));
+
+// Create database `createdBeforeDowngrading` under latest FCV
+assert.commandWorked(
+    mongos.adminCommand({enableSharding: kBeforeDowngradingDbName, primaryShard: shard0}));
+assert.commandWorked(createdBeforeDowngradingDB.coll.insert({_id: 'foo'}));
+
+// Downgrade FCV
+assert.commandWorked(mongos.adminCommand({setFeatureCompatibilityVersion: lastLTSFCV}));
+
+// Make sure movePrimary works for `createdBeforeDowngrading`
+testMovePrimary(createdBeforeDowngradingDB);
+
+// Create database `createdBeforeUpgrading` under downgraded FCV
+assert.commandWorked(mongos.adminCommand({setFeatureCompatibilityVersion: latestFCV}));
+assert.commandWorked(
+    mongos.adminCommand({enableSharding: kBeforeUpgradingDbName, primaryShard: shard0}));
+assert.commandWorked(createdBeforeUpgradingDB.coll.insert({_id: 'foo'}));
+
+// Upgrade FCV
+assert.commandWorked(mongos.adminCommand({setFeatureCompatibilityVersion: latestFCV}));
+
+// Make sure movePrimary works (again) for `createdBeforeDowngrading`
+testMovePrimary(createdBeforeDowngradingDB);
+
+// Make sure movePrimary works for `createdBeforeUpgrading`
+testMovePrimary(createdBeforeUpgradingDB);
+
+// Drop databases for next round
+assert.commandWorked(createdBeforeDowngradingDB.dropDatabase());
+assert.commandWorked(createdBeforeUpgradingDB.dropDatabase());
+
+st.stop();
+})();
diff --git a/src/mongo/db/s/move_primary_source_manager.cpp b/src/mongo/db/s/move_primary_source_manager.cpp
index 99bf70f5ba7..108871e0f4d 100644
--- a/src/mongo/db/s/move_primary_source_manager.cpp
+++ b/src/mongo/db/s/move_primary_source_manager.cpp
@@ -332,42 +332,56 @@ Status MovePrimarySourceManager::commitOnConfig(OperationContext* opCtx) {
 Status MovePrimarySourceManager::_commitOnConfig(OperationContext* opCtx) {
     auto const configShard = Grid::get(opCtx)->shardRegistry()->getConfigShard();
 
-    auto findResponse = uassertStatusOK(
-        configShard->exhaustiveFindOnConfig(opCtx,
-                                            ReadPreferenceSetting{ReadPreference::PrimaryOnly},
-                                            repl::ReadConcernLevel::kMajorityReadConcern,
-                                            DatabaseType::ConfigNS,
-                                            BSON(DatabaseType::name << _dbname),
-                                            BSON(DatabaseType::name << -1),
-                                            1));
-
-    const auto databasesVector = std::move(findResponse.docs);
-    uassert(ErrorCodes::IncompatibleShardingMetadata,
-            str::stream() << "Tried to find max database version for database '" << _dbname
-                          << "', but found no databases",
-            !databasesVector.empty());
-
-    const auto dbType = uassertStatusOK(DatabaseType::fromBSON(databasesVector.front()));
-
-    if (dbType.getPrimary() == _toShard) {
+    auto getDatabaseEntry = [&]() {
+        auto findResponse = uassertStatusOK(
+            configShard->exhaustiveFindOnConfig(opCtx,
+                                                ReadPreferenceSetting{ReadPreference::PrimaryOnly},
+                                                repl::ReadConcernLevel::kMajorityReadConcern,
+                                                DatabaseType::ConfigNS,
+                                                BSON(DatabaseType::name << _dbname),
+                                                BSON(DatabaseType::name << -1),
+                                                1));
+
+        const auto databasesVector = std::move(findResponse.docs);
+        uassert(ErrorCodes::IncompatibleShardingMetadata,
+                str::stream() << "Tried to find max database version for database '" << _dbname
+                              << "', but found no databases",
+                !databasesVector.empty());
+
+        return uassertStatusOK(DatabaseType::fromBSON(databasesVector.front()));
+    };
+
+    const auto originalDbType = getDatabaseEntry();
+
+    if (originalDbType.getPrimary() == _toShard) {
         return Status::OK();
     }
 
-    auto newDbType = dbType;
-    newDbType.setPrimary(_toShard);
-
-    auto const currentDatabaseVersion = dbType.getVersion();
-
-    newDbType.setVersion(currentDatabaseVersion.makeUpdated());
+    auto const newDbVersion = [&]() {
+        auto version = originalDbType.getVersion();
+        return version.makeUpdated();
+    }();
 
-    auto updateQueryBuilder = BSONObjBuilder(BSON(DatabaseType::name << _dbname));
-    updateQueryBuilder.append(DatabaseType::version.name(), currentDatabaseVersion.toBSON());
+    auto getDottedVersionField = [](const StringData& fieldName) {
+        return DatabaseType::version.name() + "." + fieldName;
+    };
+
+    // Include the version in the update filter to be resilient to potential network retries
+    auto const updateQuery =
+        BSON(DatabaseType::name << _dbname << getDottedVersionField(DatabaseVersion::kUuidFieldName)
+                                << newDbVersion.getUuid()
+                                << getDottedVersionField(DatabaseVersion::kLastModFieldName)
+                                << originalDbType.getVersion().getLastMod());
+    auto const update =
+        BSON("$set" << BSON(DatabaseType::primary
+                            << _toShard << getDottedVersionField(DatabaseVersion::kLastModFieldName)
+                            << newDbVersion.getLastMod()));
 
     auto updateStatus = Grid::get(opCtx)->catalogClient()->updateConfigDocument(
         opCtx,
         DatabaseType::ConfigNS,
-        updateQueryBuilder.obj(),
-        newDbType.toBSON(),
+        updateQuery,
+        update,
         false,
         ShardingCatalogClient::kMajorityWriteConcern);
 
@@ -380,6 +394,15 @@ Status MovePrimarySourceManager::_commitOnConfig(OperationContext* opCtx) {
         return updateStatus.getStatus();
     }
 
+    const auto updatedDbType = getDatabaseEntry();
+    tassert(6851100,
+            "Error committing movePrimary: database version went backwards",
+            updatedDbType.getVersion().getUuid() != originalDbType.getVersion().getUuid() ||
+                updatedDbType.getVersion().getLastMod() > originalDbType.getVersion().getLastMod());
+    uassert(6851101,
+            "Error committing movePrimary: update of `config.databases` failed",
+            updatedDbType.getPrimary() != _fromShard);
+
     return Status::OK();
 }