diff --git a/fs/Ext4.cpp b/fs/Ext4.cpp
new file mode 100644
index 0000000..3ae4159
--- /dev/null
+++ b/fs/Ext4.cpp
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <vector>
+#include <string>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/mount.h>
+#include <sys/wait.h>
+
+#include <linux/kdev_t.h>
+
+#define LOG_TAG "Vold"
+
+#include <base/logging.h>
+#include <base/stringprintf.h>
+#include <cutils/log.h>
+#include <cutils/properties.h>
+#include <logwrap/logwrap.h>
+#include <selinux/selinux.h>
+
+#include "Ext4.h"
+#include "Utils.h"
+#include "VoldUtil.h"
+
+using android::base::StringPrintf;
+
+namespace android {
+namespace vold {
+namespace ext4 {
+
+static const char* kResizefsPath = "/system/bin/resize2fs";
+static const char* kMkfsPath = "/system/bin/make_ext4fs";
+static const char* kFsckPath = "/system/bin/e2fsck";
+
+bool IsSupported() {
+    return access(kMkfsPath, X_OK) == 0
+            && access(kFsckPath, X_OK) == 0
+            && IsFilesystemSupported("ext4");
+}
+
+status_t Check(const std::string& source, const std::string& target) {
+    // The following is shamelessly borrowed from fs_mgr.c, so it should be
+    // kept in sync with any changes over there.
+
+    const char* c_source = source.c_str();
+    const char* c_target = target.c_str();
+
+    int status;
+    int ret;
+    long tmpmnt_flags = MS_NOATIME | MS_NOEXEC | MS_NOSUID;
+    char *tmpmnt_opts = (char*) "nomblk_io_submit,errors=remount-ro";
+
+    /*
+     * First try to mount and unmount the filesystem.  We do this because
+     * the kernel is more efficient than e2fsck in running the journal and
+     * processing orphaned inodes, and on at least one device with a
+     * performance issue in the emmc firmware, it can take e2fsck 2.5 minutes
+     * to do what the kernel does in about a second.
+     *
+     * After mounting and unmounting the filesystem, run e2fsck, and if an
+     * error is recorded in the filesystem superblock, e2fsck will do a full
+     * check.  Otherwise, it does nothing.  If the kernel cannot mount the
+     * filesytsem due to an error, e2fsck is still run to do a full check
+     * fix the filesystem.
+     */
+    ret = mount(c_source, c_target, "ext4", tmpmnt_flags, tmpmnt_opts);
+    if (!ret) {
+        int i;
+        for (i = 0; i < 5; i++) {
+            // Try to umount 5 times before continuing on.
+            // Should we try rebooting if all attempts fail?
+            int result = umount(c_target);
+            if (result == 0) {
+                break;
+            }
+            ALOGW("%s(): umount(%s)=%d: %s\n", __func__, c_target, result, strerror(errno));
+            sleep(1);
+        }
+    }
+
+    /*
+     * Some system images do not have e2fsck for licensing reasons
+     * (e.g. recent SDK system images). Detect these and skip the check.
+     */
+    if (access(kFsckPath, X_OK)) {
+        ALOGD("Not running %s on %s (executable not in system image)\n",
+                kFsckPath, c_source);
+    } else {
+        ALOGD("Running %s on %s\n", kFsckPath, c_source);
+
+        std::vector<std::string> cmd;
+        cmd.push_back(kFsckPath);
+        cmd.push_back("-y");
+        cmd.push_back(c_source);
+
+        // ext4 devices are currently always trusted
+        return ForkExecvp(cmd, sFsckContext);
+    }
+
+    return 0;
+}
+
+status_t Mount(const std::string& source, const std::string& target, bool ro,
+        bool remount, bool executable) {
+    int rc;
+    unsigned long flags;
+
+    const char* c_source = source.c_str();
+    const char* c_target = target.c_str();
+
+    flags = MS_NOATIME | MS_NODEV | MS_NOSUID | MS_DIRSYNC;
+
+    flags |= (executable ? 0 : MS_NOEXEC);
+    flags |= (ro ? MS_RDONLY : 0);
+    flags |= (remount ? MS_REMOUNT : 0);
+
+    rc = mount(c_source, c_target, "ext4", flags, NULL);
+
+    if (rc && errno == EROFS) {
+        SLOGE("%s appears to be a read only filesystem - retrying mount RO", c_source);
+        flags |= MS_RDONLY;
+        rc = mount(c_source, c_target, "ext4", flags, NULL);
+    }
+
+    return rc;
+}
+
+status_t Resize(const std::string& source, unsigned int numSectors) {
+    std::vector<std::string> cmd;
+    cmd.push_back(kResizefsPath);
+    cmd.push_back("-f");
+    cmd.push_back(source);
+    cmd.push_back(StringPrintf("%u", numSectors));
+
+    return ForkExecvp(cmd);
+}
+
+status_t Format(const std::string& source, unsigned int numSectors,
+        const std::string& target) {
+    std::vector<std::string> cmd;
+    cmd.push_back(kMkfsPath);
+    cmd.push_back("-J");
+
+    cmd.push_back("-a");
+    cmd.push_back(target);
+
+    if (numSectors) {
+        cmd.push_back("-l");
+        cmd.push_back(StringPrintf("%u", numSectors * 512));
+    }
+
+    // Always generate a real UUID
+    cmd.push_back("-u");
+    cmd.push_back(source);
+
+    return ForkExecvp(cmd);
+}
+
+}  // namespace ext4
+}  // namespace vold
+}  // namespace android