diff --git a/adb/Android.bp b/adb/Android.bp
index dabc5ce..a18dc1a 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -455,17 +455,14 @@
     srcs: [
         "test_adb.py",
     ],
-    libs: [
-        "adb_py",
-    ],
     test_config: "adb_integration_test_adb.xml",
     test_suites: ["general-tests"],
     version: {
         py2: {
-            enabled: true,
+            enabled: false,
         },
         py3: {
-            enabled: false,
+            enabled: true,
         },
     },
 }
diff --git a/adb/client/auth.cpp b/adb/client/auth.cpp
index 5fbef09..71c19b8 100644
--- a/adb/client/auth.cpp
+++ b/adb/client/auth.cpp
@@ -465,6 +465,7 @@
     if (key == nullptr) {
         // No more private keys to try, send the public key.
         t->SetConnectionState(kCsUnauthorized);
+        t->SetConnectionEstablished(true);
         send_auth_publickey(t);
         return;
     }
diff --git a/adb/daemon/remount_service.cpp b/adb/daemon/remount_service.cpp
index 0e79d82..f7017dd 100644
--- a/adb/daemon/remount_service.cpp
+++ b/adb/daemon/remount_service.cpp
@@ -30,6 +30,7 @@
 #include <sys/vfs.h>
 #include <unistd.h>
 
+#include <memory>
 #include <set>
 #include <string>
 #include <vector>
@@ -38,28 +39,30 @@
 #include <bootloader_message/bootloader_message.h>
 #include <cutils/android_reboot.h>
 #include <ext4_utils/ext4_utils.h>
+#include <fs_mgr.h>
+#include <fs_mgr_overlayfs.h>
 
 #include "adb.h"
 #include "adb_io.h"
 #include "adb_unique_fd.h"
 #include "adb_utils.h"
-#include "fs_mgr.h"
 #include "set_verity_enable_state_service.h"
 
-// Returns the device used to mount a directory in /proc/mounts.
+// Returns the last device used to mount a directory in /proc/mounts.
+// This will find overlayfs entry where upperdir=lowerdir, to make sure
+// remount is associated with the correct directory.
 static std::string find_proc_mount(const char* dir) {
     std::unique_ptr<FILE, int(*)(FILE*)> fp(setmntent("/proc/mounts", "r"), endmntent);
-    if (!fp) {
-        return "";
-    }
+    std::string mnt_fsname;
+    if (!fp) return mnt_fsname;
 
     mntent* e;
     while ((e = getmntent(fp.get())) != nullptr) {
         if (strcmp(dir, e->mnt_dir) == 0) {
-            return e->mnt_fsname;
+            mnt_fsname = e->mnt_fsname;
         }
     }
-    return "";
+    return mnt_fsname;
 }
 
 // Returns the device used to mount a directory in the fstab.
@@ -81,6 +84,7 @@
 }
 
 bool make_block_device_writable(const std::string& dev) {
+    if ((dev == "overlay") || (dev == "overlayfs")) return true;
     int fd = unix_open(dev.c_str(), O_RDONLY | O_CLOEXEC);
     if (fd == -1) {
         return false;
@@ -234,6 +238,14 @@
         partitions.push_back("/system");
     }
 
+    bool verity_enabled = (system_verified || vendor_verified);
+
+    // If we can use overlayfs, lets get it in place first
+    // before we struggle with determining deduplication operations.
+    if (!verity_enabled && fs_mgr_overlayfs_setup() && fs_mgr_overlayfs_mount_all()) {
+        WriteFdExactly(fd.get(), "overlayfs mounted\n");
+    }
+
     // Find partitions that are deduplicated, and can be un-deduplicated.
     std::set<std::string> dedup;
     for (const auto& partition : partitions) {
@@ -246,8 +258,6 @@
         }
     }
 
-    bool verity_enabled = (system_verified || vendor_verified);
-
     // Reboot now if the user requested it (and an operation needs a reboot).
     if (user_requested_reboot) {
         if (!dedup.empty() || verity_enabled) {
diff --git a/adb/daemon/set_verity_enable_state_service.cpp b/adb/daemon/set_verity_enable_state_service.cpp
index 2b6ec21..3676de5 100644
--- a/adb/daemon/set_verity_enable_state_service.cpp
+++ b/adb/daemon/set_verity_enable_state_service.cpp
@@ -19,6 +19,7 @@
 #include "set_verity_enable_state_service.h"
 #include "sysdeps.h"
 
+#include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
 #include <libavb_user/libavb_user.h>
@@ -28,12 +29,14 @@
 
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
+#include <fs_mgr.h>
+#include <fs_mgr_overlayfs.h>
+#include <fstab/fstab.h>
 #include <log/log_properties.h>
 
 #include "adb.h"
 #include "adb_io.h"
 #include "adb_unique_fd.h"
-#include "fs_mgr.h"
 #include "remount_service.h"
 
 #include "fec/io.h"
@@ -46,6 +49,10 @@
 static const bool kAllowDisableVerity = false;
 #endif
 
+void suggest_run_adb_root(int fd) {
+    if (getuid() != 0) WriteFdExactly(fd, "Maybe run adb root?\n");
+}
+
 /* Turn verity on/off */
 static bool set_verity_enabled_state(int fd, const char* block_device, const char* mount_point,
                                      bool enable) {
@@ -59,7 +66,7 @@
 
     if (!fh) {
         WriteFdFmt(fd, "Could not open block device %s (%s).\n", block_device, strerror(errno));
-        WriteFdFmt(fd, "Maybe run adb root?\n");
+        suggest_run_adb_root(fd);
         return false;
     }
 
@@ -87,6 +94,17 @@
         return false;
     }
 
+    auto change = false;
+    errno = 0;
+    if (enable ? fs_mgr_overlayfs_teardown(mount_point, &change)
+               : fs_mgr_overlayfs_setup(nullptr, mount_point, &change)) {
+        if (change) {
+            WriteFdFmt(fd, "%s overlayfs for %s\n", enable ? "disabling" : "using", mount_point);
+        }
+    } else if (errno) {
+        WriteFdFmt(fd, "Overlayfs %s for %s failed with error %s\n", enable ? "teardown" : "setup",
+                   mount_point, strerror(errno));
+    }
     WriteFdFmt(fd, "Verity %s on %s\n", enable ? "enabled" : "disabled", mount_point);
     return true;
 }
@@ -103,6 +121,22 @@
     return android::base::GetProperty("ro.boot.vbmeta.device_state", "") == "locked";
 }
 
+static bool overlayfs_setup(int fd, bool enable) {
+    auto change = false;
+    errno = 0;
+    if (enable ? fs_mgr_overlayfs_teardown(nullptr, &change)
+               : fs_mgr_overlayfs_setup(nullptr, nullptr, &change)) {
+        if (change) {
+            WriteFdFmt(fd, "%s overlayfs\n", enable ? "disabling" : "using");
+        }
+    } else if (errno) {
+        WriteFdFmt(fd, "Overlayfs %s failed with error %s\n", enable ? "teardown" : "setup",
+                   strerror(errno));
+        suggest_run_adb_root(fd);
+    }
+    return change;
+}
+
 /* Use AVB to turn verity on/off */
 static bool set_avb_verity_enabled_state(int fd, AvbOps* ops, bool enable_verity) {
     std::string ab_suffix = get_ab_suffix();
@@ -128,6 +162,7 @@
         return false;
     }
 
+    overlayfs_setup(fd, enable_verity);
     WriteFdFmt(fd, "Successfully %s verity\n", enable_verity ? "enabled" : "disabled");
     return true;
 }
@@ -150,6 +185,7 @@
         }
 
         if (!android::base::GetBoolProperty("ro.secure", false)) {
+            overlayfs_setup(fd, enable);
             WriteFdExactly(fd.get(), "verity not enabled - ENG build\n");
             return;
         }
@@ -177,13 +213,14 @@
         // Not using AVB - assume VB1.0.
 
         // read all fstab entries at once from all sources
-        fstab = fs_mgr_read_fstab_default();
+        if (!fstab) fstab = fs_mgr_read_fstab_default();
         if (!fstab) {
-            WriteFdExactly(fd.get(), "Failed to read fstab\nMaybe run adb root?\n");
+            WriteFdExactly(fd.get(), "Failed to read fstab\n");
+            suggest_run_adb_root(fd.get());
             return;
         }
 
-        // Loop through entries looking for ones that vold manages.
+        // Loop through entries looking for ones that verity manages.
         for (int i = 0; i < fstab->num_entries; i++) {
             if (fs_mgr_is_verified(&fstab->recs[i])) {
                 if (set_verity_enabled_state(fd.get(), fstab->recs[i].blk_device,
@@ -193,6 +230,7 @@
             }
         }
     }
+    if (!any_changed) any_changed = overlayfs_setup(fd, enable);
 
     if (any_changed) {
         WriteFdExactly(fd.get(), "Now reboot your device for settings to take effect\n");
diff --git a/adb/test_adb.py b/adb/test_adb.py
old mode 100644
new mode 100755
index ddd3ff0..d4c98e4
--- a/adb/test_adb.py
+++ b/adb/test_adb.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 # Copyright (C) 2015 The Android Open Source Project
 #
@@ -19,9 +19,7 @@
 This differs from things in test_device.py in that there is no API for these
 things. Most of these tests involve specific error messages or the help text.
 """
-from __future__ import print_function
 
-import binascii
 import contextlib
 import os
 import random
@@ -32,8 +30,6 @@
 import threading
 import unittest
 
-import adb
-
 
 @contextlib.contextmanager
 def fake_adbd(protocol=socket.AF_INET, port=0):
@@ -42,61 +38,61 @@
     serversock = socket.socket(protocol, socket.SOCK_STREAM)
     serversock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
     if protocol == socket.AF_INET:
-        serversock.bind(('127.0.0.1', port))
+        serversock.bind(("127.0.0.1", port))
     else:
-        serversock.bind(('::1', port))
+        serversock.bind(("::1", port))
     serversock.listen(1)
 
     # A pipe that is used to signal the thread that it should terminate.
-    readpipe, writepipe = os.pipe()
+    readsock, writesock = socket.socketpair()
 
-    def _adb_packet(command, arg0, arg1, data):
-        bin_command = struct.unpack('I', command)[0]
-        buf = struct.pack('IIIIII', bin_command, arg0, arg1, len(data), 0,
+    def _adb_packet(command: bytes, arg0: int, arg1: int, data: bytes) -> bytes:
+        bin_command = struct.unpack("I", command)[0]
+        buf = struct.pack("IIIIII", bin_command, arg0, arg1, len(data), 0,
                           bin_command ^ 0xffffffff)
         buf += data
         return buf
 
-    def _handle():
-        rlist = [readpipe, serversock]
-        cnxn_sent = {}
-        while True:
-            read_ready, _, _ = select.select(rlist, [], [])
-            for ready in read_ready:
-                if ready == readpipe:
-                    # Closure pipe
-                    os.close(ready)
-                    serversock.shutdown(socket.SHUT_RDWR)
-                    serversock.close()
-                    return
-                elif ready == serversock:
-                    # Server socket
-                    conn, _ = ready.accept()
-                    rlist.append(conn)
-                else:
-                    # Client socket
-                    data = ready.recv(1024)
-                    if not data or data.startswith('OPEN'):
+    def _handle(sock):
+        with contextlib.closing(sock) as serversock:
+            rlist = [readsock, serversock]
+            cnxn_sent = {}
+            while True:
+                read_ready, _, _ = select.select(rlist, [], [])
+                for ready in read_ready:
+                    if ready == readsock:
+                        # Closure pipe
+                        for f in rlist:
+                            f.close()
+                        return
+                    elif ready == serversock:
+                        # Server socket
+                        conn, _ = ready.accept()
+                        rlist.append(conn)
+                    else:
+                        # Client socket
+                        data = ready.recv(1024)
+                        if not data or data.startswith(b"OPEN"):
+                            if ready in cnxn_sent:
+                                del cnxn_sent[ready]
+                            ready.shutdown(socket.SHUT_RDWR)
+                            ready.close()
+                            rlist.remove(ready)
+                            continue
                         if ready in cnxn_sent:
-                            del cnxn_sent[ready]
-                        ready.shutdown(socket.SHUT_RDWR)
-                        ready.close()
-                        rlist.remove(ready)
-                        continue
-                    if ready in cnxn_sent:
-                        continue
-                    cnxn_sent[ready] = True
-                    ready.sendall(_adb_packet('CNXN', 0x01000001, 1024 * 1024,
-                                              'device::ro.product.name=fakeadb'))
+                            continue
+                        cnxn_sent[ready] = True
+                        ready.sendall(_adb_packet(b"CNXN", 0x01000001, 1024 * 1024,
+                                                  b"device::ro.product.name=fakeadb"))
 
     port = serversock.getsockname()[1]
-    server_thread = threading.Thread(target=_handle)
+    server_thread = threading.Thread(target=_handle, args=(serversock,))
     server_thread.start()
 
     try:
         yield port
     finally:
-        os.close(writepipe)
+        writesock.close()
         server_thread.join()
 
 
@@ -107,14 +103,15 @@
     This automatically disconnects when done with the connection.
     """
 
-    output = subprocess.check_output(['adb', 'connect', serial])
-    unittest.assertEqual(output.strip(), 'connected to {}'.format(serial))
+    output = subprocess.check_output(["adb", "connect", serial])
+    unittest.assertEqual(output.strip(),
+                        "connected to {}".format(serial).encode("utf8"))
 
     try:
         yield
     finally:
         # Perform best-effort disconnection. Discard the output.
-        subprocess.Popen(['adb', 'disconnect', serial],
+        subprocess.Popen(["adb", "disconnect", serial],
                          stdout=subprocess.PIPE,
                          stderr=subprocess.PIPE).communicate()
 
@@ -123,21 +120,22 @@
 def adb_server():
     """Context manager for an ADB server.
 
-    This creates an ADB server and returns the port it's listening on.
+    This creates an ADB server and returns the port it"s listening on.
     """
 
     port = 5038
     # Kill any existing server on this non-default port.
-    subprocess.check_output(['adb', '-P', str(port), 'kill-server'],
+    subprocess.check_output(["adb", "-P", str(port), "kill-server"],
                             stderr=subprocess.STDOUT)
     read_pipe, write_pipe = os.pipe()
-    proc = subprocess.Popen(['adb', '-L', 'tcp:localhost:{}'.format(port),
-                             'fork-server', 'server',
-                             '--reply-fd', str(write_pipe)])
+    os.set_inheritable(write_pipe, True)
+    proc = subprocess.Popen(["adb", "-L", "tcp:localhost:{}".format(port),
+                             "fork-server", "server",
+                             "--reply-fd", str(write_pipe)], close_fds=False)
     try:
         os.close(write_pipe)
         greeting = os.read(read_pipe, 1024)
-        assert greeting == 'OK\n', repr(greeting)
+        assert greeting == b"OK\n", repr(greeting)
         yield port
     finally:
         proc.terminate()
@@ -150,35 +148,37 @@
     def test_help(self):
         """Make sure we get _something_ out of help."""
         out = subprocess.check_output(
-            ['adb', 'help'], stderr=subprocess.STDOUT)
+            ["adb", "help"], stderr=subprocess.STDOUT)
         self.assertGreater(len(out), 0)
 
     def test_version(self):
         """Get a version number out of the output of adb."""
-        lines = subprocess.check_output(['adb', 'version']).splitlines()
+        lines = subprocess.check_output(["adb", "version"]).splitlines()
         version_line = lines[0]
-        self.assertRegexpMatches(
-            version_line, r'^Android Debug Bridge version \d+\.\d+\.\d+$')
+        self.assertRegex(
+            version_line, rb"^Android Debug Bridge version \d+\.\d+\.\d+$")
         if len(lines) == 2:
             # Newer versions of ADB have a second line of output for the
             # version that includes a specific revision (git SHA).
             revision_line = lines[1]
-            self.assertRegexpMatches(
-                revision_line, r'^Revision [0-9a-f]{12}-android$')
+            self.assertRegex(
+                revision_line, rb"^Revision [0-9a-f]{12}-android$")
 
     def test_tcpip_error_messages(self):
         """Make sure 'adb tcpip' parsing is sane."""
-        proc = subprocess.Popen(['adb', 'tcpip'], stdout=subprocess.PIPE,
+        proc = subprocess.Popen(["adb", "tcpip"],
+                                stdout=subprocess.PIPE,
                                 stderr=subprocess.STDOUT)
         out, _ = proc.communicate()
         self.assertEqual(1, proc.returncode)
-        self.assertIn('requires an argument', out)
+        self.assertIn(b"requires an argument", out)
 
-        proc = subprocess.Popen(['adb', 'tcpip', 'foo'], stdout=subprocess.PIPE,
+        proc = subprocess.Popen(["adb", "tcpip", "foo"],
+                                stdout=subprocess.PIPE,
                                 stderr=subprocess.STDOUT)
         out, _ = proc.communicate()
         self.assertEqual(1, proc.returncode)
-        self.assertIn('invalid port', out)
+        self.assertIn(b"invalid port", out)
 
 
 class ServerTest(unittest.TestCase):
@@ -214,12 +214,12 @@
 
         port = 5038
         # Kill any existing server on this non-default port.
-        subprocess.check_output(['adb', '-P', str(port), 'kill-server'],
+        subprocess.check_output(["adb", "-P", str(port), "kill-server"],
                                 stderr=subprocess.STDOUT)
 
         try:
             # Run the adb client and have it start the adb server.
-            proc = subprocess.Popen(['adb', '-P', str(port), 'start-server'],
+            proc = subprocess.Popen(["adb", "-P", str(port), "start-server"],
                                     stdin=subprocess.PIPE,
                                     stdout=subprocess.PIPE,
                                     stderr=subprocess.PIPE)
@@ -229,14 +229,12 @@
             stdout_thread = threading.Thread(
                 target=ServerTest._read_pipe_and_set_event,
                 args=(proc.stdout, stdout_event))
-            stdout_thread.daemon = True
             stdout_thread.start()
 
             stderr_event = threading.Event()
             stderr_thread = threading.Thread(
                 target=ServerTest._read_pipe_and_set_event,
                 args=(proc.stderr, stderr_event))
-            stderr_thread.daemon = True
             stderr_thread.start()
 
             # Wait for the adb client to finish. Once that has occurred, if
@@ -250,7 +248,8 @@
             # probably letting the adb server inherit stdin which would be
             # wrong.
             with self.assertRaises(IOError):
-                proc.stdin.write('x')
+                proc.stdin.write(b"x")
+                proc.stdin.flush()
 
             # Wait a few seconds for stdout/stderr to be closed (in the success
             # case, this won't wait at all). If there is a timeout, that means
@@ -259,9 +258,11 @@
             # inherit stdout/stderr which would be wrong.
             self.assertTrue(stdout_event.wait(5), "adb stdout not closed")
             self.assertTrue(stderr_event.wait(5), "adb stderr not closed")
+            stdout_thread.join()
+            stderr_thread.join()
         finally:
             # If we started a server, kill it.
-            subprocess.check_output(['adb', '-P', str(port), 'kill-server'],
+            subprocess.check_output(["adb", "-P", str(port), "kill-server"],
                                     stderr=subprocess.STDOUT)
 
 
@@ -271,7 +272,7 @@
     def _reset_socket_on_close(self, sock):
         """Use SO_LINGER to cause TCP RST segment to be sent on socket close."""
         # The linger structure is two shorts on Windows, but two ints on Unix.
-        linger_format = 'hh' if os.name == 'nt' else 'ii'
+        linger_format = "hh" if os.name == "nt" else "ii"
         l_onoff = 1
         l_linger = 0
 
@@ -292,33 +293,33 @@
             # Use SO_REUSEADDR so subsequent runs of the test can grab the port
             # even if it is in TIME_WAIT.
             listener.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-            listener.bind(('127.0.0.1', 0))
+            listener.bind(("127.0.0.1", 0))
             listener.listen(4)
             port = listener.getsockname()[1]
 
             # Now that listening has started, start adb emu kill, telling it to
             # connect to our mock emulator.
             proc = subprocess.Popen(
-                ['adb', '-s', 'emulator-' + str(port), 'emu', 'kill'],
+                ["adb", "-s", "emulator-" + str(port), "emu", "kill"],
                 stderr=subprocess.STDOUT)
 
             accepted_connection, addr = listener.accept()
             with contextlib.closing(accepted_connection) as conn:
                 # If WSAECONNABORTED (10053) is raised by any socket calls,
                 # then adb probably isn't reading the data that we sent it.
-                conn.sendall('Android Console: type \'help\' for a list ' +
-                             'of commands\r\n')
-                conn.sendall('OK\r\n')
+                conn.sendall(("Android Console: type 'help' for a list "
+                             "of commands\r\n").encode("utf8"))
+                conn.sendall(b"OK\r\n")
 
                 with contextlib.closing(conn.makefile()) as connf:
                     line = connf.readline()
-                    if line.startswith('auth'):
+                    if line.startswith("auth"):
                         # Ignore the first auth line.
                         line = connf.readline()
-                    self.assertEqual('kill\n', line)
-                    self.assertEqual('quit\n', connf.readline())
+                    self.assertEqual("kill\n", line)
+                    self.assertEqual("quit\n", connf.readline())
 
-                conn.sendall('OK: killing emulator, bye bye\r\n')
+                conn.sendall(b"OK: killing emulator, bye bye\r\n")
 
                 # Use SO_LINGER to send TCP RST segment to test whether adb
                 # ignores WSAECONNRESET on Windows. This happens with the
@@ -342,31 +343,31 @@
         """
         with adb_server() as server_port:
             with fake_adbd() as port:
-                serial = 'emulator-{}'.format(port - 1)
+                serial = "emulator-{}".format(port - 1)
                 # Ensure that the emulator is not there.
                 try:
-                    subprocess.check_output(['adb', '-P', str(server_port),
-                                             '-s', serial, 'get-state'],
+                    subprocess.check_output(["adb", "-P", str(server_port),
+                                             "-s", serial, "get-state"],
                                             stderr=subprocess.STDOUT)
-                    self.fail('Device should not be available')
+                    self.fail("Device should not be available")
                 except subprocess.CalledProcessError as err:
                     self.assertEqual(
                         err.output.strip(),
-                        'error: device \'{}\' not found'.format(serial))
+                        "error: device '{}' not found".format(serial).encode("utf8"))
 
                 # Let the ADB server know that the emulator has started.
                 with contextlib.closing(
-                    socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
-                    sock.connect(('localhost', server_port))
-                    command = 'host:emulator:{}'.format(port)
-                    sock.sendall('%04x%s' % (len(command), command))
+                        socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
+                    sock.connect(("localhost", server_port))
+                    command = "host:emulator:{}".format(port).encode("utf8")
+                    sock.sendall(b"%04x%s" % (len(command), command))
 
                 # Ensure the emulator is there.
-                subprocess.check_call(['adb', '-P', str(server_port),
-                                       '-s', serial, 'wait-for-device'])
-                output = subprocess.check_output(['adb', '-P', str(server_port),
-                                                  '-s', serial, 'get-state'])
-                self.assertEqual(output.strip(), 'device')
+                subprocess.check_call(["adb", "-P", str(server_port),
+                                       "-s", serial, "wait-for-device"])
+                output = subprocess.check_output(["adb", "-P", str(server_port),
+                                                  "-s", serial, "get-state"])
+                self.assertEqual(output.strip(), b"device")
 
 
 class ConnectionTest(unittest.TestCase):
@@ -380,7 +381,7 @@
         for protocol in (socket.AF_INET, socket.AF_INET6):
             try:
                 with fake_adbd(protocol=protocol) as port:
-                    serial = 'localhost:{}'.format(port)
+                    serial = "localhost:{}".format(port)
                     with adb_connect(self, serial):
                         pass
             except socket.error:
@@ -391,49 +392,51 @@
         """Ensure that an already-connected device stays connected."""
 
         with fake_adbd() as port:
-            serial = 'localhost:{}'.format(port)
+            serial = "localhost:{}".format(port)
             with adb_connect(self, serial):
                 # b/31250450: this always returns 0 but probably shouldn't.
-                output = subprocess.check_output(['adb', 'connect', serial])
+                output = subprocess.check_output(["adb", "connect", serial])
                 self.assertEqual(
-                    output.strip(), 'already connected to {}'.format(serial))
+                    output.strip(),
+                    "already connected to {}".format(serial).encode("utf8"))
 
     def test_reconnect(self):
         """Ensure that a disconnected device reconnects."""
 
         with fake_adbd() as port:
-            serial = 'localhost:{}'.format(port)
+            serial = "localhost:{}".format(port)
             with adb_connect(self, serial):
-                output = subprocess.check_output(['adb', '-s', serial,
-                                                  'get-state'])
-                self.assertEqual(output.strip(), 'device')
+                output = subprocess.check_output(["adb", "-s", serial,
+                                                  "get-state"])
+                self.assertEqual(output.strip(), b"device")
 
                 # This will fail.
-                proc = subprocess.Popen(['adb', '-s', serial, 'shell', 'true'],
+                proc = subprocess.Popen(["adb", "-s", serial, "shell", "true"],
                                         stdout=subprocess.PIPE,
                                         stderr=subprocess.STDOUT)
                 output, _ = proc.communicate()
-                self.assertEqual(output.strip(), 'error: closed')
+                self.assertEqual(output.strip(), b"error: closed")
 
-                subprocess.check_call(['adb', '-s', serial, 'wait-for-device'])
+                subprocess.check_call(["adb", "-s", serial, "wait-for-device"])
 
-                output = subprocess.check_output(['adb', '-s', serial,
-                                                  'get-state'])
-                self.assertEqual(output.strip(), 'device')
+                output = subprocess.check_output(["adb", "-s", serial,
+                                                  "get-state"])
+                self.assertEqual(output.strip(), b"device")
 
                 # Once we explicitly kick a device, it won't attempt to
                 # reconnect.
-                output = subprocess.check_output(['adb', 'disconnect', serial])
+                output = subprocess.check_output(["adb", "disconnect", serial])
                 self.assertEqual(
-                    output.strip(), 'disconnected {}'.format(serial))
+                    output.strip(),
+                    "disconnected {}".format(serial).encode("utf8"))
                 try:
-                    subprocess.check_output(['adb', '-s', serial, 'get-state'],
+                    subprocess.check_output(["adb", "-s", serial, "get-state"],
                                             stderr=subprocess.STDOUT)
-                    self.fail('Device should not be available')
+                    self.fail("Device should not be available")
                 except subprocess.CalledProcessError as err:
                     self.assertEqual(
                         err.output.strip(),
-                        'error: device \'{}\' not found'.format(serial))
+                        "error: device '{}' not found".format(serial).encode("utf8"))
 
 
 def main():
@@ -442,5 +445,5 @@
     unittest.main(verbosity=3)
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     main()
diff --git a/adb/test_device.py b/adb/test_device.py
index 4abe7a7..42aadc4 100644
--- a/adb/test_device.py
+++ b/adb/test_device.py
@@ -762,9 +762,10 @@
             os.chmod(host_dir, 0o700)
 
             # Create an empty directory.
-            os.mkdir(os.path.join(host_dir, 'empty'))
+            empty_dir_path = os.path.join(host_dir, 'empty')
+            os.mkdir(empty_dir_path);
 
-            self.device.push(host_dir, self.DEVICE_TEMP_DIR)
+            self.device.push(empty_dir_path, self.DEVICE_TEMP_DIR)
 
             test_empty_cmd = ['[', '-d',
                               os.path.join(self.DEVICE_TEMP_DIR, 'empty')]
@@ -1032,7 +1033,8 @@
             if host_dir is not None:
                 shutil.rmtree(host_dir)
 
-    def test_pull_symlink_dir(self):
+    # selinux prevents adbd from accessing symlinks on /data/local/tmp.
+    def disabled_test_pull_symlink_dir(self):
         """Pull a symlink to a directory of symlinks to files."""
         try:
             host_dir = tempfile.mkdtemp()
diff --git a/adb/transport.cpp b/adb/transport.cpp
index 3c74c75..0e8db04 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -1190,14 +1190,15 @@
 }
 #endif  // ADB_HOST
 
-int register_socket_transport(unique_fd s, std::string serial, int port, int local,
-                              atransport::ReconnectCallback reconnect) {
+bool register_socket_transport(unique_fd s, std::string serial, int port, int local,
+                               atransport::ReconnectCallback reconnect, int* error) {
     atransport* t = new atransport(std::move(reconnect), kCsOffline);
 
     D("transport: %s init'ing for socket %d, on port %d", serial.c_str(), s.get(), port);
     if (init_socket_transport(t, std::move(s), port, local) < 0) {
         delete t;
-        return -1;
+        if (error) *error = errno;
+        return false;
     }
 
     std::unique_lock<std::recursive_mutex> lock(transport_lock);
@@ -1206,7 +1207,8 @@
             VLOG(TRANSPORT) << "socket transport " << transport->serial
                             << " is already in pending_list and fails to register";
             delete t;
-            return -EALREADY;
+            if (error) *error = EALREADY;
+            return false;
         }
     }
 
@@ -1215,7 +1217,8 @@
             VLOG(TRANSPORT) << "socket transport " << transport->serial
                             << " is already in transport_list and fails to register";
             delete t;
-            return -EALREADY;
+            if (error) *error = EALREADY;
+            return false;
         }
     }
 
@@ -1229,10 +1232,20 @@
 
     if (local == 1) {
         // Do not wait for emulator transports.
-        return 0;
+        return true;
     }
 
-    return waitable->WaitForConnection(std::chrono::seconds(10)) ? 0 : -1;
+    if (!waitable->WaitForConnection(std::chrono::seconds(10))) {
+        if (error) *error = ETIMEDOUT;
+        return false;
+    }
+
+    if (t->GetConnectionState() == kCsUnauthorized) {
+        if (error) *error = EPERM;
+        return false;
+    }
+
+    return true;
 }
 
 #if ADB_HOST
diff --git a/adb/transport.h b/adb/transport.h
index 4bfc2ce..f362f24 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -364,8 +364,8 @@
 void connect_device(const std::string& address, std::string* response);
 
 /* cause new transports to be init'd and added to the list */
-int register_socket_transport(unique_fd s, std::string serial, int port, int local,
-                              atransport::ReconnectCallback reconnect);
+bool register_socket_transport(unique_fd s, std::string serial, int port, int local,
+                               atransport::ReconnectCallback reconnect, int* error = nullptr);
 
 // This should only be used for transports with connection_state == kCsNoPerm.
 void unregister_usb_transport(usb_handle* usb);
diff --git a/adb/transport_local.cpp b/adb/transport_local.cpp
index b20dee9..1431252 100644
--- a/adb/transport_local.cpp
+++ b/adb/transport_local.cpp
@@ -125,10 +125,12 @@
         return init_socket_transport(t, std::move(fd), port, 0) >= 0;
     };
 
-    int ret = register_socket_transport(std::move(fd), serial, port, 0, std::move(reconnect));
-    if (ret < 0) {
-        if (ret == -EALREADY) {
+    int error;
+    if (!register_socket_transport(std::move(fd), serial, port, 0, std::move(reconnect), &error)) {
+        if (error == EALREADY) {
             *response = android::base::StringPrintf("already connected to %s", serial.c_str());
+        } else if (error == EPERM) {
+            *response = android::base::StringPrintf("failed to authenticate to %s", serial.c_str());
         } else {
             *response = android::base::StringPrintf("failed to connect to %s", serial.c_str());
         }
@@ -162,7 +164,7 @@
         disable_tcp_nagle(fd.get());
         std::string serial = getEmulatorSerialString(console_port);
         if (register_socket_transport(std::move(fd), std::move(serial), adb_port, 1,
-                                      [](atransport*) { return false; }) == 0) {
+                                      [](atransport*) { return false; })) {
             return 0;
         }
     }
diff --git a/base/include/android-base/parsedouble.h b/base/include/android-base/parsedouble.h
index 7b1c648..ccffba2 100644
--- a/base/include/android-base/parsedouble.h
+++ b/base/include/android-base/parsedouble.h
@@ -20,6 +20,7 @@
 #include <stdlib.h>
 
 #include <limits>
+#include <string>
 
 namespace android {
 namespace base {
@@ -52,6 +53,11 @@
                                double max = std::numeric_limits<double>::max()) {
   return ParseFloatingPoint<double, strtod>(s, out, min, max);
 }
+static inline bool ParseDouble(const std::string& s, double* out,
+                               double min = std::numeric_limits<double>::lowest(),
+                               double max = std::numeric_limits<double>::max()) {
+  return ParseFloatingPoint<double, strtod>(s.c_str(), out, min, max);
+}
 
 // Parse float value in the string 's' and sets 'out' to that value if it exists.
 // Optionally allows the caller to define a 'min' and 'max' beyond which
@@ -61,6 +67,11 @@
                               float max = std::numeric_limits<float>::max()) {
   return ParseFloatingPoint<float, strtof>(s, out, min, max);
 }
+static inline bool ParseFloat(const std::string& s, float* out,
+                              float min = std::numeric_limits<float>::lowest(),
+                              float max = std::numeric_limits<float>::max()) {
+  return ParseFloatingPoint<float, strtof>(s.c_str(), out, min, max);
+}
 
 }  // namespace base
 }  // namespace android
diff --git a/fs_mgr/Android.bp b/fs_mgr/Android.bp
index 196321c..6329d54 100644
--- a/fs_mgr/Android.bp
+++ b/fs_mgr/Android.bp
@@ -43,6 +43,7 @@
         "fs_mgr_avb.cpp",
         "fs_mgr_avb_ops.cpp",
         "fs_mgr_dm_linear.cpp",
+        "fs_mgr_overlayfs.cpp",
     ],
     shared_libs: [
         "libfec",
diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index 5f57182..99f2df8 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "fs_mgr.h"
+
 #include <ctype.h>
 #include <dirent.h>
 #include <errno.h>
@@ -51,6 +53,7 @@
 #include <ext4_utils/ext4_sb.h>
 #include <ext4_utils/ext4_utils.h>
 #include <ext4_utils/wipe.h>
+#include <fs_mgr_overlayfs.h>
 #include <libdm/dm.h>
 #include <linux/fs.h>
 #include <linux/loop.h>
@@ -58,7 +61,6 @@
 #include <log/log_properties.h>
 #include <logwrap/logwrap.h>
 
-#include "fs_mgr.h"
 #include "fs_mgr_avb.h"
 #include "fs_mgr_priv.h"
 
@@ -1035,6 +1037,10 @@
         }
     }
 
+#if ALLOW_ADBD_DISABLE_VERITY == 1  // "userdebug" build
+    fs_mgr_overlayfs_mount_all();
+#endif
+
     if (error_count) {
         return FS_MGR_MNTALL_FAIL;
     } else {
diff --git a/fs_mgr/fs_mgr_overlayfs.cpp b/fs_mgr/fs_mgr_overlayfs.cpp
new file mode 100644
index 0000000..bafa2b3
--- /dev/null
+++ b/fs_mgr/fs_mgr_overlayfs.cpp
@@ -0,0 +1,478 @@
+/*
+ * Copyright (C) 2018 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 <dirent.h>
+#include <errno.h>
+#include <linux/fs.h>
+#include <selinux/selinux.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <android-base/file.h>
+#include <android-base/macros.h>
+#include <android-base/properties.h>
+#include <android-base/strings.h>
+#include <fs_mgr_overlayfs.h>
+#include <fstab/fstab.h>
+
+#include "fs_mgr_priv.h"
+
+using namespace std::literals;
+
+#if ALLOW_ADBD_DISABLE_VERITY == 0  // If we are a user build, provide stubs
+
+bool fs_mgr_overlayfs_mount_all() {
+    return false;
+}
+
+bool fs_mgr_overlayfs_setup(const char*, const char*, bool* change) {
+    if (change) change = false;
+    return false;
+}
+
+bool fs_mgr_overlayfs_teardown(const char*, bool* change) {
+    if (change) change = false;
+    return false;
+}
+
+#else  // ALLOW_ADBD_DISABLE_VERITY == 0
+
+namespace {
+
+// acceptable overlayfs backing storage
+const auto kOverlayMountPoint = "/cache"s;
+
+// return true if everything is mounted, but before adb is started.  At
+// 'trigger firmware_mounts_complete' after 'trigger load_persist_props_action'.
+bool fs_mgr_boot_completed() {
+    return !android::base::GetProperty("ro.boottime.init", "").empty() &&
+           !!access("/dev/.booting", F_OK);
+}
+
+bool fs_mgr_is_dir(const std::string& path) {
+    struct stat st;
+    return !stat(path.c_str(), &st) && S_ISDIR(st.st_mode);
+}
+
+// Similar test as overlayfs workdir= validation in the kernel for read-write
+// validation, except we use fs_mgr_work.  Covers space and storage issues.
+bool fs_mgr_dir_is_writable(const std::string& path) {
+    auto test_directory = path + "/fs_mgr_work";
+    rmdir(test_directory.c_str());
+    auto ret = !mkdir(test_directory.c_str(), 0700);
+    return ret | !rmdir(test_directory.c_str());
+}
+
+std::string fs_mgr_get_context(const std::string& mount_point) {
+    char* ctx = nullptr;
+    auto len = getfilecon(mount_point.c_str(), &ctx);
+    if ((len > 0) && ctx) {
+        std::string context(ctx, len);
+        free(ctx);
+        return context;
+    }
+    return "";
+}
+
+bool fs_mgr_overlayfs_enabled(const struct fstab_rec* fsrec) {
+    // readonly filesystem, can not be mount -o remount,rw
+    return "squashfs"s == fsrec->fs_type;
+}
+
+constexpr char upper_name[] = "upper";
+constexpr char work_name[] = "work";
+
+std::string fs_mgr_get_overlayfs_candidate(const std::string& mount_point) {
+    if (!fs_mgr_is_dir(mount_point)) return "";
+    auto dir = kOverlayMountPoint + "/overlay/" + android::base::Basename(mount_point) + "/";
+    auto upper = dir + upper_name;
+    if (!fs_mgr_is_dir(upper)) return "";
+    auto work = dir + work_name;
+    if (!fs_mgr_is_dir(work)) return "";
+    if (!fs_mgr_dir_is_writable(work)) return "";
+    return dir;
+}
+
+constexpr char lowerdir_option[] = "lowerdir=";
+constexpr char upperdir_option[] = "upperdir=";
+
+// default options for mount_point, returns empty string for none available.
+std::string fs_mgr_get_overlayfs_options(const char* mount_point) {
+    auto fsrec_mount_point = std::string(mount_point);
+    auto candidate = fs_mgr_get_overlayfs_candidate(fsrec_mount_point);
+    if (candidate.empty()) return "";
+
+    auto context = fs_mgr_get_context(fsrec_mount_point);
+    if (!context.empty()) context = ",rootcontext="s + context;
+    return "override_creds=off,"s + lowerdir_option + fsrec_mount_point + "," + upperdir_option +
+           candidate + upper_name + ",workdir=" + candidate + work_name + context;
+}
+
+bool fs_mgr_system_root_image(const fstab* fstab) {
+    if (!fstab) {  // can not happen?
+        // This will return empty on init first_stage_mount,
+        // hence why we prefer checking the fstab instead.
+        return android::base::GetBoolProperty("ro.build.system_root_image", false);
+    }
+    for (auto i = 0; i < fstab->num_entries; i++) {
+        const auto fsrec = &fstab->recs[i];
+        auto fsrec_mount_point = fsrec->mount_point;
+        if (!fsrec_mount_point) continue;
+        if ("/system"s == fsrec_mount_point) return false;
+    }
+    return true;
+}
+
+std::string fs_mgr_get_overlayfs_options(const fstab* fstab, const char* mount_point) {
+    if (fs_mgr_system_root_image(fstab) && ("/"s == mount_point)) mount_point = "/system";
+
+    return fs_mgr_get_overlayfs_options(mount_point);
+}
+
+// return true if system supports overlayfs
+bool fs_mgr_wants_overlayfs() {
+    // This will return empty on init first_stage_mount, so speculative
+    // determination, empty (unset) _or_ "1" is true which differs from the
+    // official ro.debuggable policy.  ALLOW_ADBD_DISABLE_VERITY == 0 should
+    // protect us from false in any case, so this is insurance.
+    auto debuggable = android::base::GetProperty("ro.debuggable", "1");
+    if (debuggable != "1") return false;
+
+    // Overlayfs available in the kernel, and patched for override_creds?
+    static signed char overlayfs_in_kernel = -1;  // cache for constant condition
+    if (overlayfs_in_kernel == -1) {
+        overlayfs_in_kernel = !access("/sys/module/overlay/parameters/override_creds", F_OK);
+    }
+    return overlayfs_in_kernel;
+}
+
+bool fs_mgr_wants_overlayfs(const fstab_rec* fsrec) {
+    if (!fsrec) return false;
+
+    auto fsrec_mount_point = fsrec->mount_point;
+    if (!fsrec_mount_point) return false;
+
+    if (!fsrec->fs_type) return false;
+
+    // Don't check entries that are managed by vold.
+    if (fsrec->fs_mgr_flags & (MF_VOLDMANAGED | MF_RECOVERYONLY)) return false;
+
+    // Only concerned with readonly partitions.
+    if (!(fsrec->flags & MS_RDONLY)) return false;
+
+    // If unbindable, do not allow overlayfs as this could expose us to
+    // security issues.  On Android, this could also be used to turn off
+    // the ability to overlay an otherwise acceptable filesystem since
+    // /system and /vendor are never bound(sic) to.
+    if (fsrec->flags & MS_UNBINDABLE) return false;
+
+    if (!fs_mgr_overlayfs_enabled(fsrec)) return false;
+
+    // Verity enabled?
+    const auto basename_mount_point(android::base::Basename(fsrec_mount_point));
+    auto found = false;
+    fs_mgr_update_verity_state(
+            [&basename_mount_point, &found](fstab_rec*, const char* mount_point, int, int) {
+                if (mount_point && (basename_mount_point == mount_point)) found = true;
+            });
+    return !found;
+}
+
+bool fs_mgr_rm_all(const std::string& path, bool* change = nullptr) {
+    auto save_errno = errno;
+    std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(path.c_str()), closedir);
+    if (!dir) {
+        if (errno == ENOENT) {
+            errno = save_errno;
+            return true;
+        }
+        PERROR << "overlayfs open " << path;
+        return false;
+    }
+    dirent* entry;
+    auto ret = true;
+    while ((entry = readdir(dir.get()))) {
+        if (("."s == entry->d_name) || (".."s == entry->d_name)) continue;
+        auto file = path + "/" + entry->d_name;
+        if (entry->d_type == DT_UNKNOWN) {
+            struct stat st;
+            if (!lstat(file.c_str(), &st) && (st.st_mode & S_IFDIR)) entry->d_type = DT_DIR;
+        }
+        if (entry->d_type == DT_DIR) {
+            ret &= fs_mgr_rm_all(file, change);
+            if (!rmdir(file.c_str())) {
+                if (change) *change = true;
+            } else {
+                ret = false;
+                PERROR << "overlayfs rmdir " << file;
+            }
+            continue;
+        }
+        if (!unlink(file.c_str())) {
+            if (change) *change = true;
+        } else {
+            ret = false;
+            PERROR << "overlayfs rm " << file;
+        }
+    }
+    return ret;
+}
+
+bool fs_mgr_overlayfs_setup_one(const std::string& overlay, const std::string& mount_point,
+                                bool* change) {
+    auto ret = true;
+    auto fsrec_mount_point = overlay + android::base::Basename(mount_point) + "/";
+    auto save_errno = errno;
+    if (!mkdir(fsrec_mount_point.c_str(), 0755)) {
+        if (change) *change = true;
+    } else if (errno != EEXIST) {
+        ret = false;
+        PERROR << "overlayfs mkdir " << fsrec_mount_point;
+    } else {
+        errno = save_errno;
+    }
+
+    save_errno = errno;
+    if (!mkdir((fsrec_mount_point + work_name).c_str(), 0755)) {
+        if (change) *change = true;
+    } else if (errno != EEXIST) {
+        ret = false;
+        PERROR << "overlayfs mkdir " << fsrec_mount_point << work_name;
+    } else {
+        errno = save_errno;
+    }
+
+    auto new_context = fs_mgr_get_context(mount_point);
+    if (!new_context.empty() && setfscreatecon(new_context.c_str())) {
+        ret = false;
+        PERROR << "overlayfs setfscreatecon " << new_context;
+    }
+    auto upper = fsrec_mount_point + upper_name;
+    save_errno = errno;
+    if (!mkdir(upper.c_str(), 0755)) {
+        if (change) *change = true;
+    } else if (errno != EEXIST) {
+        ret = false;
+        PERROR << "overlayfs mkdir " << upper;
+    } else {
+        errno = save_errno;
+    }
+    if (!new_context.empty()) setfscreatecon(nullptr);
+
+    return ret;
+}
+
+bool fs_mgr_overlayfs_mount(const fstab* fstab, const fstab_rec* fsrec) {
+    if (!fs_mgr_wants_overlayfs(fsrec)) return false;
+    auto fsrec_mount_point = fsrec->mount_point;
+    if (!fsrec_mount_point || !fsrec_mount_point[0]) return false;
+    auto options = fs_mgr_get_overlayfs_options(fstab, fsrec_mount_point);
+    if (options.empty()) return false;
+
+    // hijack __mount() report format to help triage
+    auto report = "__mount(source=overlay,target="s + fsrec_mount_point + ",type=overlay";
+    const auto opt_list = android::base::Split(options, ",");
+    for (const auto opt : opt_list) {
+        if (android::base::StartsWith(opt, upperdir_option)) {
+            report = report + "," + opt;
+            break;
+        }
+    }
+    report = report + ")=";
+
+    auto ret = mount("overlay", fsrec_mount_point, "overlay", MS_RDONLY | MS_RELATIME,
+                     options.c_str());
+    if (ret) {
+        PERROR << report << ret;
+        return false;
+    } else {
+        LINFO << report << ret;
+        return true;
+    }
+}
+
+bool fs_mgr_overlayfs_already_mounted(const char* mount_point) {
+    if (!mount_point) return false;
+    std::unique_ptr<struct fstab, decltype(&fs_mgr_free_fstab)> fstab(
+            fs_mgr_read_fstab("/proc/mounts"), fs_mgr_free_fstab);
+    if (!fstab) return false;
+    const auto lowerdir = std::string(lowerdir_option) + mount_point;
+    for (auto i = 0; i < fstab->num_entries; ++i) {
+        const auto fsrec = &fstab->recs[i];
+        const auto fs_type = fsrec->fs_type;
+        if (!fs_type) continue;
+        if (("overlay"s != fs_type) && ("overlayfs"s != fs_type)) continue;
+        auto fsrec_mount_point = fsrec->mount_point;
+        if (!fsrec_mount_point) continue;
+        if (strcmp(fsrec_mount_point, mount_point)) continue;
+        const auto fs_options = fsrec->fs_options;
+        if (!fs_options) continue;
+        const auto options = android::base::Split(fs_options, ",");
+        for (const auto opt : options) {
+            if (opt == lowerdir) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+}  // namespace
+
+bool fs_mgr_overlayfs_mount_all() {
+    auto ret = false;
+
+    if (!fs_mgr_wants_overlayfs()) return ret;
+
+    std::unique_ptr<struct fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
+                                                                      fs_mgr_free_fstab);
+    if (!fstab) return ret;
+
+    for (auto i = 0; i < fstab->num_entries; i++) {
+        const auto fsrec = &fstab->recs[i];
+        auto fsrec_mount_point = fsrec->mount_point;
+        if (!fsrec_mount_point) continue;
+        if (fs_mgr_overlayfs_already_mounted(fsrec_mount_point)) continue;
+
+        if (fs_mgr_overlayfs_mount(fstab.get(), fsrec)) ret = true;
+    }
+    return ret;
+}
+
+// Returns false if setup not permitted, errno set to last error.
+// If something is altered, set *change.
+bool fs_mgr_overlayfs_setup(const char* backing, const char* mount_point, bool* change) {
+    if (change) *change = false;
+    auto ret = false;
+    if (backing && (kOverlayMountPoint != backing)) {
+        errno = EINVAL;
+        return ret;
+    }
+    if (!fs_mgr_wants_overlayfs()) return ret;
+    if (!fs_mgr_boot_completed()) {
+        errno = EBUSY;
+        PERROR << "overlayfs setup";
+        return ret;
+    }
+
+    std::unique_ptr<struct fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
+                                                                      fs_mgr_free_fstab);
+    std::vector<std::string> mounts;
+    if (fstab) {
+        if (!fs_mgr_get_entry_for_mount_point(fstab.get(), kOverlayMountPoint)) return ret;
+        for (auto i = 0; i < fstab->num_entries; i++) {
+            const auto fsrec = &fstab->recs[i];
+            auto fsrec_mount_point = fsrec->mount_point;
+            if (!fsrec_mount_point) continue;
+            if (mount_point && strcmp(fsrec_mount_point, mount_point)) continue;
+            if (!fs_mgr_wants_overlayfs(fsrec)) continue;
+            mounts.emplace_back(fsrec_mount_point);
+        }
+        if (mounts.empty()) return ret;
+    }
+
+    if (mount_point && ("/"s == mount_point) && fs_mgr_system_root_image(fstab.get())) {
+        mount_point = "/system";
+    }
+    auto overlay = kOverlayMountPoint + "/overlay/";
+    auto save_errno = errno;
+    if (!mkdir(overlay.c_str(), 0755)) {
+        if (change) *change = true;
+    } else if (errno != EEXIST) {
+        PERROR << "overlayfs mkdir " << overlay;
+    } else {
+        errno = save_errno;
+    }
+    if (!fstab && mount_point && fs_mgr_overlayfs_setup_one(overlay, mount_point, change)) {
+        ret = true;
+    }
+    for (const auto& fsrec_mount_point : mounts) {
+        ret |= fs_mgr_overlayfs_setup_one(overlay, fsrec_mount_point, change);
+    }
+    return ret;
+}
+
+// Returns false if teardown not permitted, errno set to last error.
+// If something is altered, set *change.
+bool fs_mgr_overlayfs_teardown(const char* mount_point, bool* change) {
+    if (change) *change = false;
+    if (mount_point && ("/"s == mount_point)) {
+        std::unique_ptr<struct fstab, decltype(&fs_mgr_free_fstab)> fstab(
+                fs_mgr_read_fstab_default(), fs_mgr_free_fstab);
+        if (fs_mgr_system_root_image(fstab.get())) mount_point = "/system";
+    }
+    auto ret = true;
+    const auto overlay = kOverlayMountPoint + "/overlay";
+    const auto oldpath = overlay + (mount_point ?: "");
+    const auto newpath = oldpath + ".teardown";
+    ret &= fs_mgr_rm_all(newpath);
+    auto save_errno = errno;
+    if (rename(oldpath.c_str(), newpath.c_str())) {
+        if (change) *change = true;
+    } else if (errno != ENOENT) {
+        ret = false;
+        PERROR << "overlayfs mv " << oldpath << " " << newpath;
+    } else {
+        errno = save_errno;
+    }
+    ret &= fs_mgr_rm_all(newpath, change);
+    save_errno = errno;
+    if (!rmdir(newpath.c_str())) {
+        if (change) *change = true;
+    } else if (errno != ENOENT) {
+        ret = false;
+        PERROR << "overlayfs rmdir " << newpath;
+    } else {
+        errno = save_errno;
+    }
+    if (mount_point) {
+        save_errno = errno;
+        if (!rmdir(overlay.c_str())) {
+            if (change) *change = true;
+        } else if ((errno != ENOENT) && (errno != ENOTEMPTY)) {
+            ret = false;
+            PERROR << "overlayfs rmdir " << overlay;
+        } else {
+            errno = save_errno;
+        }
+    }
+    if (!fs_mgr_wants_overlayfs()) {
+        // After obligatory teardown to make sure everything is clean, but if
+        // we didn't want overlayfs in the the first place, we do not want to
+        // waste time on a reboot (or reboot request message).
+        if (change) *change = false;
+    }
+    // And now that we did what we could, lets inform
+    // caller that there may still be more to do.
+    if (!fs_mgr_boot_completed()) {
+        errno = EBUSY;
+        PERROR << "overlayfs teardown";
+        ret = false;
+    }
+    return ret;
+}
+
+#endif  // ALLOW_ADBD_DISABLE_VERITY != 0
diff --git a/fs_mgr/include/fs_mgr_overlayfs.h b/fs_mgr/include/fs_mgr_overlayfs.h
new file mode 100644
index 0000000..1d2ff03
--- /dev/null
+++ b/fs_mgr/include/fs_mgr_overlayfs.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+#pragma once
+
+#include <fstab/fstab.h>
+
+bool fs_mgr_overlayfs_mount_all();
+bool fs_mgr_overlayfs_setup(const char* backing = nullptr, const char* mount_point = nullptr,
+                            bool* change = nullptr);
+bool fs_mgr_overlayfs_teardown(const char* mount_point = nullptr, bool* change = nullptr);
diff --git a/init/first_stage_mount.cpp b/init/first_stage_mount.cpp
index 41e8fff..0c5cf76 100644
--- a/init/first_stage_mount.cpp
+++ b/init/first_stage_mount.cpp
@@ -35,6 +35,7 @@
 #include "fs_mgr.h"
 #include "fs_mgr_avb.h"
 #include "fs_mgr_dm_linear.h"
+#include "fs_mgr_overlayfs.h"
 #include "uevent.h"
 #include "uevent_listener.h"
 #include "util.h"
@@ -351,6 +352,7 @@
             return false;
         }
     }
+    fs_mgr_overlayfs_mount_all();
     return true;
 }