hi,

> Ok, for the sake of arguement, how do you propose we arrange to skip the 
> lookup for "c" in general? Right now, the only code that knows about 
> tearing path names into components is in namei(9), so how do we get the 
> VOP_LOOKUP(c) to be skipped? Also, the right thing needs to happen for "rm 
> foo" too.

"NOLEAF" flag for NDINIT?  (or, alternatively, "WANTLEAF")

> Also, think about the case where / and /usr are separate file systems. 
> Right now sys_unlink() handles that case. If we push the vnode lookup into 
> the file system, they each have to try and get the vnode, to see if 
> there's a file system mounted above it.

i think (dvp, name) pair is enough to check if it's a mount point or not
in that case.  it isn't very pretty, though.

YAMAMOTO Takashi