Proved first subspec (read_first_block_ok) and other bunch of side lemmas.
Proved first subspec (read_first_block_ok) and other bunch of side lemmas.

mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl,mit-pdos/fscq-impl