Try to mount new filesystem w/ ext2 first, then ext3.

postinstall_runner_action_unittest.cc

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
+
 #include <string>
 #include <vector>
+
+#include <base/string_util.h>
 #include <gtest/gtest.h>
+
 #include "update_engine/postinstall_runner_action.h"
 #include "update_engine/test_utils.h"
 #include "update_engine/utils.h"
 
 using std::string;
 using std::vector;
 
 namespace chromeos_update_engine {
 
 namespace {
@@ skipping 62 matching lines @@
     cwd = string(&buf[0], strlen(&buf[0]));
   }
 
   // create the au destination, if it doesn't exist
   ASSERT_EQ(0, System(string("mkdir -p ") + mountpoint));
 
   // create 10MiB sparse file
   ASSERT_EQ(0, system("dd if=/dev/zero of=image.dat seek=10485759 bs=1 "
                       "count=1"));
 
-  // format it as ext3
-  ASSERT_EQ(0, system("mkfs.ext3 -F image.dat"));
+  // format it as ext2
+  ASSERT_EQ(0, system("mkfs.ext2 -F image.dat"));
 
   // mount it
   ASSERT_EQ(0, System(string("mount -o loop image.dat ") + mountpoint));
 
   // put a postinst script in
-  string script = string("#!/bin/bash\ntouch ") + cwd + "/postinst_called\n";
+  string script = StringPrintf("#!/bin/bash\n"
+                               "mount | grep au_postint_mount | grep ext2\n"
+                               "if [ $? -eq 0 ]; then\n"
+                               "  touch %s/postinst_called\n"
+                               "fi\n",
+                               cwd.c_str());
   if (do_err_script) {
     script = "#!/bin/bash\nexit 1";
   }
   ASSERT_TRUE(WriteFileString(mountpoint + "/postinst", script));
   ASSERT_EQ(0, System(string("chmod a+x ") + mountpoint + "/postinst"));
 
   ASSERT_EQ(0, System(string("umount -d ") + mountpoint));
 
   ASSERT_EQ(0, System(string("rm -f ") + cwd + "/postinst_called"));
 
@@ skipping 60 matching lines @@
 
 // Death tests don't seem to be working on Hardy
 TEST_F(PostinstallRunnerActionTest, DISABLED_RunAsRootDeathTest) {
   ASSERT_EQ(0, getuid());
   PostinstallRunnerAction runner_action;
   ASSERT_DEATH({ runner_action.TerminateProcessing(); },
                "postinstall_runner_action.h:.*] Check failed");
 }
 
 }  // namespace chromeos_update_engine