Direct I/O support (patches included)

[Linda Walsh]

Sorry for the multiple posts, am thinking about this problem
in between working on other stuff... and stuff comes up.

But bottom line -- I would look at the source of coreutils "dd" program
and find out how they do direct I/O.  I know they had to deal with
alignment issues when the Linux kernel became alignment sensitive.
So I'd see how they did things and make sure I had the same
checks and bounds on my buffers.