- move log into metadata part of disk, so that marking
that the log's blocks are in use falls out for free
- superblock describes the whole disk (sizes and offets)
- sizes and offsets are computed in one place (mkfs) and
the rest of the code refers to the superblock for these values,
instead of recomputing them.

instead of 1.   ideintr() should wait for nsector_per_block interrupts before
waking up the reader; now it wakes up the reader after 1 interrupt, which
apparently means that the first sector is available of the command instead of all.
For now keep BSIZE to 512.

that they can be different.  Clean up mkfs, simplifying specifying fs parameters,
remove some redundancy between fs and mkfs, and fix disk layout bugs. Call blocks
in the file system blocks instead of sectors.  Passes usertests for different
block sizes.

Passes usertests and stressfs
Seems to recover correctly in a number of simple cases

fix race in mknod / creat
use last component in dirent in mknod, not path

nit in sbrk
indirect block
fix dup to share fd struct

fix acquire() to cli() *before* incrementing nlock
make T_SYSCALL a trap gate, not an interrupt gate
sadly, various crashes if you hold down a keyboard key...

O_RDWR, etc.
create file

balloc

iget
mkfs makes a file system image
put this in your .bochsrc:
ata0-slave: type=disk, mode=flat, path="fs.img", cylinders=1024, heads=1, spt=1