tree 3bae85341246871d28f9f843491439c6973de3dd
parent 961c25aba9898ac2e1629c745914e4c2f2a68301
author Alex Deymo <deymo@google.com> 1458956902 -0700
committer Alex Deymo <deymo@google.com> 1460514901 -0700

Mark block device as read-only before mounting.

Mounting a block device as read-only still allows the filesystem to
write to the block device, while keeping the user-facing filesystem
interface "read-only". This behavior will make dm-verity to fail after
reboot if any block is modified during postinstall.

This patch marks the block device as read-only before mounting it, and
marks them read-only or read-write before using them during the update.

Bug: 27859604
TEST=Added logging and deployed an update to brillo, devices are marked RO/RW as needed during a delta update.

(cherry picked from commit 5fb356cac8a87c62fa83005d99370aa2f8416064)

Change-Id: I8797c35514e1f38c2a0395cedc8e1dce53e28350