SERVER-35629 Use WiredTiger salvage API to repair corrupt metadata

(cherry picked from commit 3acf1742d7bcec78997614edb1e8ef26ccf2331f)

2 files changed, 82 insertions, 1 deletions

diff --git a/jstests/disk/wt_corrupt_file_errors.js b/jstests/disk/wt_corrupt_file_errors.js
index f6e7204ccbf..5f829e5de8f 100644
--- a/jstests/disk/wt_corrupt_file_errors.js
+++ b/jstests/disk/wt_corrupt_file_errors.js
@@ -47,7 +47,7 @@
             const WiredTigerWTFile = dbpath + "WiredTiger.wt";
             jsTestLog("corrupting WiredTiger.wt");
             corruptFile(WiredTigerWTFile);
-        }, "Fatal Assertion 28595");
+        }, "Fatal Assertion 50944");
 
     /**
      * Test 4. Corrupt an index file.
diff --git a/jstests/disk/wt_repair_corrupt_metadata.js b/jstests/disk/wt_repair_corrupt_metadata.js
new file mode 100644
index 00000000000..16c12ac9bd7
--- /dev/null
+++ b/jstests/disk/wt_repair_corrupt_metadata.js
@@ -0,0 +1,81 @@
+/**
+ * Tests that --repair on WiredTiger correctly and gracefully handles corrupt metadata files.
+ *
+ * @tags: [requires_wiredtiger,requires_journaling]
+ */
+
+(function() {
+
+    load('jstests/disk/libs/wt_file_helper.js');
+
+    const baseName = "wt_repair_corrupt_metadata";
+    const collName = "test";
+    const dbpath = MongoRunner.dataPath + baseName + "/";
+
+    /**
+     * This test runs repair using a version of the WiredTiger.turtle file that has checkpoint
+     * information before the collection was created. The turtle file contains checkpoint
+     * information about the WiredTiger.wt file, so if these two files become out of sync,
+     * WiredTiger will have to attempt a salvage operation on the .wt file and rebuild the .turtle
+     * file.
+     *
+     * The expectation is that the metadata salvage will be successful, and that the collection will
+     * be recreated with all of its data.
+     */
+    let runTest = function(mongodOptions) {
+        // Unfortunately using --nojournal triggers a WT_PANIC and aborts in debug builds, which the
+        // following test case can exercise.
+        // TODO: This return can be removed once WT-4310 is completed.
+        if (db.adminCommand('buildInfo').debug && mongodOptions.hasOwnProperty('nojournal')) {
+            jsTestLog(
+                "Skipping test case because this is a debug build and --nojournal was provided.");
+            return;
+        }
+
+        resetDbpath(dbpath);
+        jsTestLog("Running test with args: " + tojson(mongodOptions));
+
+        const turtleFile = dbpath + "WiredTiger.turtle";
+        const turtleFileWithoutCollection = dbpath + "WiredTiger.turtle.1";
+
+        let mongod = startMongodOnExistingPath(dbpath, mongodOptions);
+
+        // Force a checkpoint and make a copy of the turtle file.
+        assert.commandWorked(mongod.getDB(baseName).adminCommand({fsync: 1}));
+        jsTestLog("Making copy of metadata file before creating the collection: " +
+                  turtleFileWithoutCollection);
+        copyFile(turtleFile, turtleFileWithoutCollection);
+
+        let testColl = mongod.getDB(baseName)[collName];
+        assert.commandWorked(testColl.insert({a: 1}));
+
+        // Force another checkpoint before a clean shutdown.
+        assert.commandWorked(mongod.getDB(baseName).adminCommand({fsync: 1}));
+        MongoRunner.stopMongod(mongod);
+
+        // Guarantee the turtle files changed between checkpoints.
+        assert.neq(md5sumFile(turtleFileWithoutCollection), md5sumFile(turtleFile));
+
+        jsTestLog("Replacing metadata file with a version before the collection existed.");
+        removeFile(turtleFile);
+        copyFile(turtleFileWithoutCollection, turtleFile);
+
+        assertRepairSucceeds(dbpath, mongod.port, mongodOptions);
+
+        mongod = startMongodOnExistingPath(dbpath, mongodOptions);
+        testColl = mongod.getDB(baseName)[collName];
+
+        // The collection exists depite using an older turtle file because salvage is able to find
+        // the table in the WiredTiger.wt file.
+        assert(testColl.exists());
+        // We can assert that the data exists because the salvage only took place on the metadata,
+        // not the data.
+        assert.eq(testColl.find({}).itcount(), 1);
+        MongoRunner.stopMongod(mongod);
+    };
+
+    // Repair may behave differently with journaling enabled or disabled, but the end result should
+    // be the same.
+    runTest({journal: ""});
+    runTest({nojournal: ""});
+})();