From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751909AbcGXOXR (ORCPT ); Sun, 24 Jul 2016 10:23:17 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:48870 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751427AbcGXOXQ (ORCPT ); Sun, 24 Jul 2016 10:23:16 -0400 Date: Sun, 24 Jul 2016 15:23:07 +0100 From: Al Viro To: "J. Bruce Fields" Cc: "J. Bruce Fields" , Oleg Drokin , Jeff Layton , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/7] nfsd: remove redundant i_lookup check Message-ID: <20160724142306.GO2356@ZenIV.linux.org.uk> References: <1469209736-6490-1-git-send-email-bfields@redhat.com> <1469209736-6490-4-git-send-email-bfields@redhat.com> <20160724002152.GN2356@ZenIV.linux.org.uk> <20160724121014.GA20985@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160724121014.GA20985@fieldses.org> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 24, 2016 at 08:10:14AM -0400, J. Bruce Fields wrote: > 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" > > > > > > 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. First of all, such objects do exist; they probably won't be encountered by nfsd and all instances I can think of are not writable, but... > 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. I'd have turned that into d_can_lookup(fhp->fh_dentry), actually.