Re: [PATCH 3/7] nfsd: remove redundant i_lookup check

[J. Bruce Fields]

On Sun, Jul 24, 2016 at 01:22:06AM +0100, Al Viro wrote:
> On Fri, Jul 22, 2016 at 01:48:52PM -0400, J. Bruce Fields wrote:
> > From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
> > 
> > I'm not sure why this was added.  It doesn't seem necessary, and no
> > other caller does this.
> 
> lookup_one_len() will explode if you call it for non-directory (==
> !d_can_lookup(), i.e. something without ->lookup()).  So unless the callers
> do guarantee that check being true, it *is* needed.

Both callers call fh_verify(.,.,S_IFDIR,.), so at this point we know
that i_mode & S_IFMT == S_IFDIR.  Is there some odd case where that's
insufficient?  If so, I think there may be bugs elsewhere in nfsd.  If
not, I'll add a note to the changelog.

Thanks for reminding me to check this, I hadn't thought of that as an
"is this a directory" check, it makes more sense now.

--b.