Add a postinstall script for GC on F2FS

This script is intended to run on F2FS checkpointing devices.
It triggers garbage collection for a period of time to make
mounting with checkpoint=disable smoother.

Test: Set this script as a postinstall script on vendor
Bug: 123367711
Change-Id: I87e143a2004da5852654688c3c8773510b7073ae

2 files changed, 64 insertions, 0 deletions

diff --git a/checkpoint_gc/Android.bp b/checkpoint_gc/Android.bp
new file mode 100644
index 00000000..fac9c6a8
--- /dev/null
+++ b/checkpoint_gc/Android.bp
@@ -0,0 +1,6 @@
+// Checkpointing GC script
+sh_binary {
+    name: "checkpoint_gc",
+    src: "checkpoint_gc.sh",
+    vendor: true,
+}
diff --git a/checkpoint_gc/checkpoint_gc.sh b/checkpoint_gc/checkpoint_gc.sh
new file mode 100644
index 00000000..bf86e214
--- /dev/null
+++ b/checkpoint_gc/checkpoint_gc.sh
@@ -0,0 +1,58 @@
+#!/system/bin/sh
+
+#
+# Copyright (C) 2019 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.
+#
+
+# This script will run as an pre-checkpointing cleanup for mounting f2fs
+# with checkpoint=disable, so that the first mount after the reboot will
+# be faster. It is unnecessary to run if the device does not use userdata
+# checkpointing on F2FS.
+
+# TARGET_SLOT="${1}"
+STATUS_FD="${2}"
+GC_TIME=120
+DIRTY_SEGMENTS_THRESHOLD=100
+
+NAME=`while read dev dir type opt; do
+  if [ /data = ${dir} -a f2fs = ${type} ]; then
+    echo ${dev##*/}
+    break
+  fi
+done < /proc/mounts`
+if [ -z "${NAME}" ]; then
+  exit 0
+fi
+log -pi -t checkpoint_gc Turning on GC for ${NAME}
+echo 1 > /sys/fs/f2fs/${NAME}/gc_urgent || exit 1
+
+COUNT=0
+STEP=5
+while [ ${COUNT} -lt ${GC_TIME} ]; do
+  print -u${STATUS_FD} "global_progress `echo $COUNT/$GC_TIME|bc -l`"
+  read DIRTY_SEGMENTS < /sys/fs/f2fs/${NAME}/dirty_segments
+  if [ ${DIRTY_SEGMENTS} -le ${DIRTY_SEGMENTS_THRESHOLD} ]; then
+    break
+  fi
+  sleep ${STEP}
+  COUNT=$((${COUNT}+${STEP}))
+done
+
+log -pi -t checkpoint_gc Turning off GC for ${NAME}
+echo 0 > /sys/fs/f2fs/${NAME}/gc_urgent
+sync
+
+print -u${STATUS_FD} "global_progress 1.0"
+exit 0