Our thin block wrappers exposed buffer heads to all the callers. We're
about to revert back to the block interface that uses its own
scoutfs_block struct instead of buffer heads. Let's reduce the churn of
that patch by first having the block API give callers an opaque struct
scoutfs_block. Internally it's still buffer heads but the callers don't
know that.
scoutfs_write_dirty_super() is the exception who has magical knowledge
of buffer heads. That's fixed once the new block API offers a function
for writing a single block.
Signed-off-by: Zach Brown <zab@versity.com>
Reviewed-by: Mark Fasheh <mfasheh@versity.com>