diff --git a/fs_mgr/tests/Android.bp b/fs_mgr/tests/Android.bp
index ea12e96..565597a 100644
--- a/fs_mgr/tests/Android.bp
+++ b/fs_mgr/tests/Android.bp
@@ -36,3 +36,20 @@
         "-Werror",
     ],
 }
+
+cc_prebuilt_binary {
+    name: "adb-remount-test.sh",
+    srcs: ["adb-remount-test.sh"],
+    target: {
+        darwin: {
+            enabled: false,
+        },
+        windows: {
+            enabled: false,
+        },
+        android: {
+            enabled: false,
+        },
+    },
+    host_supported: true,
+}
diff --git a/fs_mgr/tests/adb-remount-test.sh b/fs_mgr/tests/adb-remount-test.sh
index 7fc9518..e4ff765 100755
--- a/fs_mgr/tests/adb-remount-test.sh
+++ b/fs_mgr/tests/adb-remount-test.sh
@@ -11,23 +11,23 @@
 ##  USAGE
 ##
 
-USAGE="USAGE: `basename ${0}` [-s <SerialNumber>]
+USAGE="USAGE: `basename ${0}` [--help] [--serial <SerialNumber>] [--color]
 
-adb remount tests (overlayfs focus)
+adb remount tests
+
+--help      This help
+--serial    Specify device (must if multiple are present)
+--color     Dress output with highlighting colors
 
 Conditions:
  - Must be a userdebug build.
  - Must be in adb mode.
- - Kernel must have overlayfs enabled and patched to support override_creds.
- - Must have either squashfs, ext4-dedupe or right-sized partitions.
- - Minimum expectation system and vender are overlayfs covered partitions.
+ - Also tests overlayfs
+  - Kernel must have overlayfs enabled and patched to support override_creds.
+  - Must have either erofs, squashfs, ext4-dedupe or full partitions.
+  - Minimum expectation system and vender are overlayfs covered partitions.
 "
 
-if [ X"${1}" = X"--help" -o X"${1}" = X"-h" -o X"${1}" = X"-?" ]; then
-  echo "${USAGE}" >&2
-  exit 0
-fi
-
 ##
 ##  Helper Variables
 ##
@@ -44,6 +44,7 @@
 ORANGE="${ESCAPE}[38;5;255:165:0m"
 BLUE="${ESCAPE}[35m"
 NORMAL="${ESCAPE}[0m"
+TMPDIR=${TMPDIR:-/tmp}
 
 ##
 ##  Helper Functions
@@ -293,13 +294,22 @@
   echo ${O} >&2
 }
 
+[ "USAGE: restore
+
+Do nothing: should be redefined when necessary.  Called after cleanup.
+
+Returns: reverses configurations" ]
+restore() {
+  true
+}
+
 [ "USAGE: cleanup
 
 Do nothing: should be redefined when necessary
 
-Returns: cleans up any latent resources, reverses configurations" ]
-cleanup () {
-  :
+Returns: cleans up any latent resources" ]
+cleanup() {
+  true
 }
 
 [ "USAGE: die [-d|-t <epoch>] [message] >/dev/stderr
@@ -321,6 +331,7 @@
   fi
   echo "${RED}[  FAILED  ]${NORMAL} ${@}" >&2
   cleanup
+  restore
   exit 1
 }
 
@@ -413,9 +424,48 @@
 ##  MAINLINE
 ##
 
-if [ X"-s" = X"${1}" -a -n "${2}" ]; then
-  export ANDROID_SERIAL="${2}"
-  shift 2
+OPTIONS=`getopt --alternative --unquoted --longoptions help,serial:,colour,color,no-colour,no-color -- "?hs:" ${*}` ||
+  ( echo "${USAGE}" >&2 ; false ) ||
+  die "getopt failure"
+set -- ${OPTIONS}
+
+color=false
+while [ ${#} -gt 0 ]; do
+  case ${1} in
+    -h | --help | -\?)
+      echo "${USAGE}" >&2
+      exit 0
+      ;;
+    -s | --serial)
+      export ANDROID_SERIAL=${2}
+      shift
+      ;;
+    --color | --colour)
+      color=true
+      ;;
+    --no-color | --no-colour)
+      color=false
+      ;;
+    --)
+      shift
+      break
+      ;;
+    -*)
+      echo "${USAGE}" >&2
+      die "${0}: error unknown option ${1}"
+      ;;
+    *)
+      break
+      ;;
+  esac
+  shift
+done
+if ! ${color}; then
+  GREEN=""
+  RED=""
+  ORANGE=""
+  BLUE=""
+  NORMAL=""
 fi
 
 inFastboot && die "device in fastboot mode"
@@ -451,15 +501,43 @@
 [ -z "${BUILD_DESCRIPTION}" ] ||
   echo "${BLUE}[     INFO ]${NORMAL} ${BUILD_DESCRIPTION}" >&2
 
-VERITY_WAS_ENABLED=false
+# Report existing partition sizes
+adb_sh ls -l /dev/block/by-name/ </dev/null 2>/dev/null |
+  sed -n 's@.* \([^ ]*\) -> /dev/block/\([^ ]*\)$@\1 \2@p' |
+  while read name device; do
+    case ${name} in
+      system_[ab] | system | vendor_[ab] | vendor | super | cache)
+        case ${device} in
+          sd*)
+            device=${device%%[0-9]*}/${device}
+            ;;
+        esac
+        size=`adb_su cat /sys/block/${device}/size 2>/dev/null </dev/null` &&
+          size=`expr ${size} / 2` &&
+          echo "${BLUE}[     INFO ]${NORMAL} partition ${name} device ${device} size ${size}K" >&2
+        ;;
+    esac
+  done
+
+# Can we test remount -R command?
+overlayfs_supported=true
 if [ "orange" = "`get_property ro.boot.verifiedbootstate`" -a \
      "2" = "`get_property partition.system.verified`" ]; then
-  VERITY_WAS_ENABLED=true
+  restore() {
+    ${overlayfs_supported} || return 0
+    echo "${GREEN}[     INFO ]${NORMAL} restoring verity" >&2
+    inFastboot &&
+      fastboot reboot &&
+      adb_wait 2m
+    adb_root &&
+      adb enable-verity &&
+      adb_reboot &&
+      adb_wait 2m
+  }
 fi
 
 echo "${GREEN}[ RUN      ]${NORMAL} Testing kernel support for overlayfs" >&2
 
-overlayfs_supported=true;
 adb_wait || die "wait for device failed"
 adb_sh ls -d /sys/module/overlay </dev/null >/dev/null 2>/dev/null ||
   adb_sh grep "nodev${TAB}overlay" /proc/filesystems </dev/null >/dev/null 2>/dev/null &&
@@ -478,7 +556,7 @@
           echo "${ORANGE}[  WARNING ]${NORMAL} overlay module does not support override_creds" >&2 &&
           false
         ) ||
-        overlayfs_supported=false;
+        overlayfs_supported=false
       ;;
     *)
       echo "${GREEN}[       OK ]${NORMAL} overlay module uses callers creds" >&2
@@ -550,8 +628,8 @@
 H=`adb disable-verity 2>&1`
 err=${?}
 L=
-D="${H%?Now reboot your device for settings to take effect}"
-if [ X"${D}" != X"${D##*using overlayfs}" ]; then
+D="${H%?Now reboot your device for settings to take effect*}"
+if [ X"${D}" != X"${D##*[Uu]sing overlayfs}" ]; then
   echo "${GREEN}[       OK ]${NORMAL} using overlayfs" >&2
 fi
 if [ ${err} != 0 ]; then
@@ -583,8 +661,8 @@
   T=`adb_date`
   H=`adb disable-verity 2>&1`
   err=${?}
-  D="${H%?Now reboot your device for settings to take effect}"
-  if [ X"${D}" != X"${D##*using overlayfs}" ]; then
+  D="${H%?Now reboot your device for settings to take effect*}"
+  if [ X"${D}" != X"${D##*[Uu]sing overlayfs}" ]; then
     echo "${GREEN}[       OK ]${NORMAL} using overlayfs" >&2
   fi
   if [ ${err} != 0 ]; then
@@ -615,7 +693,11 @@
 
 echo "${GREEN}[ RUN      ]${NORMAL} remount" >&2
 
-adb remount ||
+D=`adb remount 2>&1`
+ret=${?}
+echo "${D}"
+[ ${ret} != 0 ] ||
+  [ X"${D}" = X"${D##*remount failed}" ] ||
   ( [ -n "${L}" ] && echo "${L}" && false ) ||
   die -t "${T}" "adb remount failed"
 D=`adb_sh df -k </dev/null` &&
@@ -665,10 +747,33 @@
     die  "overlay takeover after remount"
   !(adb_sh grep "^overlay " /proc/mounts </dev/null |
     skip_unrelated_mounts |
-    grep " overlay ro,") &&
-    !(adb_sh grep " rw," /proc/mounts </dev/null |
-      skip_administrative_mounts data) ||
+    grep " overlay ro,") ||
     die "remount overlayfs missed a spot (ro)"
+  D=`adb_sh grep " rw," /proc/mounts </dev/null |
+     skip_administrative_mounts data`
+  if echo "${D}" | grep /dev/root >/dev/null; then
+    D=`echo / /
+       echo "${D}" | grep -v /dev/root`
+  fi
+  D=`echo "${D}" | cut -s -d' ' -f1 | sort -u`
+  bad_rw=false
+  for d in ${D}; do
+    if adb_sh tune2fs -l $d 2>&1 |
+       grep "Filesystem features:.*shared_blocks" >/dev/null; then
+      bad_rw=true
+    else
+      d=`adb_sh df -k ${D} </dev/null |
+       sed 's@\([%] /\)\(apex\|bionic\|system\|vendor\)/[^ ][^ ]*$@\1@'`
+      [ X"${d}" = X"${d##* 100[%] }" ] ||
+        bad_rw=true
+    fi
+  done
+  [ -z "${D}" ] ||
+    D=`adb_sh df -k ${D} </dev/null |
+       sed -e 's@\([%] /\)\(apex\|bionic\|system\|vendor\)/[^ ][^ ]*$@\1@' \
+           -e 's/^Filesystem      /Filesystem (rw) /'`
+  [ -z "${D}" ] || echo "${D}"
+  ${bad_rw} && die "remount overlayfs missed a spot (rw)"
 else
   if [ ${ret} = 0 ]; then
     die -t ${T} "unexpected overlay takeover"
@@ -721,7 +826,7 @@
 
   adb_su sed -n '1,/overlay \/system/p' /proc/mounts </dev/null |
     skip_administrative_mounts |
-    grep -v ' \(squashfs\|ext4\|f2fs\|vfat\) ' &&
+    grep -v ' \(erofs\|squashfs\|ext4\|f2fs\|vfat\) ' &&
     echo "${ORANGE}[  WARNING ]${NORMAL} overlay takeover after first stage init" >&2 ||
     echo "${GREEN}[       OK ]${NORMAL} overlay takeover in first stage init" >&2
 fi
@@ -749,7 +854,10 @@
   adb pull /system/lib/bootstrap/libc.so ${tempdir}/libc.so.fromdevice >/dev/null ||
   die "pull libc.so from device"
 diff ${tempdir}/libc.so ${tempdir}/libc.so.fromdevice > /dev/null || die "libc.so differ"
-rm -r ${tempdir}
+rm -rf ${tempdir}
+cleanup() {
+  true
+}
 echo "${GREEN}[       OK ]${NORMAL} /system/lib/bootstrap/libc.so content remains after reboot" >&2
 
 echo "${GREEN}[ RUN      ]${NORMAL} flash vendor, confirm its content disappears" >&2
@@ -762,10 +870,14 @@
   echo "${ORANGE}[  WARNING ]${NORMAL} vendor image missing, skipping"
 elif [ "${ANDROID_PRODUCT_OUT}" = "${ANDROID_PRODUCT_OUT%*/${H}}" ]; then
   echo "${ORANGE}[  WARNING ]${NORMAL} wrong vendor image, skipping"
+elif [ -z "${ANDROID_HOST_OUT}" ]; then
+  echo "${ORANGE}[  WARNING ]${NORMAL} please run lunch, skipping"
 else
-  adb reboot-fastboot &&
-    fastboot_wait 2m &&
-    fastboot flash vendor ||
+  adb reboot-fastboot ||
+    die "fastbootd not supported (wrong adb in path?)"
+  fastboot_wait 2m ||
+    die "reboot into fastboot to flash vendor `usb_status`"
+  fastboot flash vendor ||
     ( fastboot reboot && false) ||
     die "fastboot flash vendor"
   fastboot_getvar is-userspace yes &&
@@ -804,7 +916,7 @@
     die "can not reboot out of fastboot"
   echo "${ORANGE}[  WARNING ]${NORMAL} adb after fastboot"
   adb_wait 2m ||
-    die "did not reboot after flash"
+    die "did not reboot after flash `usb_status`"
   if ${overlayfs_needed}; then
     adb_root &&
       D=`adb_sh df -k </dev/null` &&
@@ -847,7 +959,7 @@
 H=`adb remount 2>&1`
 err=${?}
 L=
-D="${H%?Now reboot your device for settings to take effect}"
+D="${H%?Now reboot your device for settings to take effect*}"
 if [ X"${H}" != X"${D}" ]; then
   echo "${ORANGE}[  WARNING ]${NORMAL} adb remount requires a reboot after partial flash (legacy avb)"
   L=`adb_logcat -b all -v nsec -t ${T} 2>&1`
@@ -878,17 +990,18 @@
 
   adb reboot-fastboot ||
     die "Reboot into fastbootd"
+  img=${TMPDIR}/adb-remount-test-${$}.img
   cleanup() {
-    rm /tmp/adb-remount-test.img
+    rm ${img}
   }
-  dd if=/dev/zero of=/tmp/adb-remount-test.img bs=4096 count=16 2>/dev/null &&
+  dd if=/dev/zero of=${img} bs=4096 count=16 2>/dev/null &&
     fastboot_wait 2m ||
-    die "reboot into fastboot"
-  fastboot flash --force ${scratch_partition} /tmp/adb-remount-test.img
+    die "reboot into fastboot `usb_status`"
+  fastboot flash --force ${scratch_partition} ${img}
   err=${?}
   cleanup
   cleanup() {
-    :
+    true
   }
   fastboot reboot ||
     die "can not reboot out of fastboot"
@@ -900,14 +1013,32 @@
   T=`adb_date`
   D=`adb disable-verity 2>&1`
   err=${?}
-  adb remount ||
-    die "remount failed"
+  if [ X"${D}" != "${D%?Now reboot your device for settings to take effect*}" ]
+  then
+    echo "${ORANGE}[  WARNING ]${NORMAL} adb disable-verity requires a reboot after partial flash"
+    adb_reboot &&
+      adb_wait 2m &&
+      adb_root ||
+      die "failed to reboot"
+    T=`adb_date`
+    D="${D}
+`adb disable-verity 2>&1`"
+    err=${?}
+  fi
+
   echo "${D}"
   [ ${err} = 0 ] &&
     [ X"${D}" = X"${D##*setup failed}" ] &&
-    [ X"${D}" != X"${D##*using overlayfs}" ] &&
+    [ X"${D}" != X"${D##*[Uu]sing overlayfs}" ] &&
     echo "${GREEN}[       OK ]${NORMAL} ${scratch_partition} recreated" >&2 ||
     die -t ${T} "setup for overlayfs"
+  D=`adb remount 2>&1`
+  err=${?}
+  echo "${D}"
+  [ ${err} != 0 ] ||
+    [ X"${D}" = X"${D##*remount failed}" ] ||
+    ( echo "${D}" && false ) ||
+    die -t ${T} "remount failed"
 fi
 
 echo "${GREEN}[ RUN      ]${NORMAL} test raw remount commands" >&2
@@ -924,12 +1055,12 @@
   die "/vendor is not read-write"
 echo "${GREEN}[       OK ]${NORMAL} mount -o rw,remount command works" >&2
 
-if $VERITY_WAS_ENABLED && $overlayfs_supported; then
-  adb_root &&
-    adb enable-verity &&
-    adb_reboot &&
-    adb_wait 2m ||
-    die "failed to restore verity" >&2
-fi
+restore
+err=${?}
+restore() {
+  true
+}
+[ ${err} = 0 ] ||
+  die "failed to restore verity" >&2
 
 echo "${GREEN}[  PASSED  ]${NORMAL} adb remount" >&2