Merge changes from topic "sys_rootdisk" am: 4c7dc7bd1d am: 09dc4e679d am: 397e014a13

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2008276

Change-Id: I73724e4b42bb56e3e9359a5dc7da6e474eb777a4