> > lfs uses special block number, UNWRITTEN (== -2).
> > although they shouldn't go to disk, you can find them in
> > in-core inodes/indirect blocks.
> 
> I still don't see why it would matter, then.  At the point these routines are 
> called, having such a block number present would at best cause us to try to 
> read a non-existant portion of the disk.  It would indicate a bug elsewhere.

i don't think so.
reading the block number doesn't always imply reading the block
pointed by it.

> That said, we really need to clean this stuff up and make it unsigned clean.

i have no objection if you're going to make lfs unsigned clean.

YAMAMOTO Takashi