init: early_mount: add support to mount non-verity partitions early

This is done by parsing 'androidboot.fstab=<fstab>' kernel cmdline
option to get the fstab file that *only* specifies partitions to be
mounted early (i.e. in init's first stage).

Note that, the same fstab file may not be used as an argument to
mount_all later in the boot as that will cause fs_mgr to fail with
EBUSY.

TODO:
- Possibly add a new mount_mode so the same fstab can be used for
early_mount, 'mount_all --early/--late' etc.
- Add support for dm-verity enabled partitions to mount early.
- Add support for getting fstab arguments through DT instead of kernel
cmdline.

Bug: 27805372

Test:
Boot angler by passing a seperate fstab file using the kernel
cmdline option to mount vendor partition early, remove the vendor
partition entry from the main fstab file for the test.

Boot sailfish by passing a seperate fstab entry via device tree
to mount vendor partition early. Remove vendor partition entry from
the main fstab file for the test

Change-Id: I18785b893c54c8cee960ab44d5e8f83e5d624aa8
Signed-off-by: Sandeep Patil <sspatil@google.com>

0 files changed, 0 insertions, 0 deletions