- drop the notion of frags (LFS fragments) vs fsb (FFS fragments)
The code uses a complicated unity function that just makes the
code difficult to understand.
- support larger sector sizes. Fix disk address computations
to use DEV_BSIZE in the kernel as required by device drivers
and to use sector sizes in userland.
- Fix several locking bugs in lfs_bio.c and lfs_subr.c.