> > > For the flag changes, I'd add O_ALT_IO and O_OTHER (other is droppable if
> > > objectionalbe). These flags can be set at open or via F_SETFL. They would
> > > correspond to FALTIO and FOTHER for kernel-internal flags. Add
> > > IO_ALTSEMANTICS and IO_OTHER flags to i/o flags passed to
> > > VOP_READ & VOP_WRITE. vn_read() and vn_write() would set these flags
> > > (respectivly) if the F flags were set for the file.
> > 
> > I see no well-defined meaning for what these flags do.  As such, it
> > seems highly inappropriate to add them.
>
> The ALT_IO case, at least, specifies that "file-system-specific alternate
> semantics" are to be used.  Since these are file-system specific, defining
> them specifically in a generic header file doesn't even make sense.

`Give this man a ceeegar!'

That's precisely the point.  It looks to me like you're trying to
create some `generic' interface where it simply isn't appropriate.
FS-specific ioctl(2)s could easily handle this operation, without
needing to `infect' the VFS interface at all.