Logistics for adb remount on developer builds for readonly system
partitions using overlayfs to deal with not being able to remount
with read-write.
Conditions are that filesystem is squashfs, read-only, debug build,
kernel supports overlayfs. The default is a valid /cache/overlay/
directory, with .../<mount_point>/upper and .../<mount_point>/work,
associated with each system partition <mount_point>.
Will take the sepolicy of context of lowerdir as rootcontext= option.
Add fs_mgr_overlayfs_mount_all() to recurse through
fs_mgr_read_fstab_default(), and checking against /proc/mounts to
add any acceptable overlayfs mounts. The checking with /proc/mounts
makes sure we do not overlayfs overtop an overlayfs.
Add fs_mgr_overlayfs_setup(const char*, const char* bool*) and
fs_mgr_overlayfs_teardown(const char*, bool*) to respectively setup
or teardown the overlayfs support directories. Return value
includes success and optional supplied change booleans.
Test: compile
Bug: 109821005
Bug: 110985612
Change-Id: Ie9b4e9ca0f2bdd9275ac2e2e905431636948e131
b28389f5ee