From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932261AbWFGPjY (ORCPT ); Wed, 7 Jun 2006 11:39:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932266AbWFGPjY (ORCPT ); Wed, 7 Jun 2006 11:39:24 -0400 Received: from pat.uio.no ([129.240.10.4]:63656 "EHLO pat.uio.no") by vger.kernel.org with ESMTP id S932261AbWFGPjY (ORCPT ); Wed, 7 Jun 2006 11:39:24 -0400 Subject: Re: [NFS] [PATCH] NFS server does not update mtime on setattr request From: Trond Myklebust To: Peter Staubach Cc: "J. Bruce Fields" , Neil Brown , NFS List , Linux Kernel Mailing List In-Reply-To: <4486F020.3030707@redhat.com> References: <4485C3FE.5070504@redhat.com> <1149658707.27298.10.camel@localhost> <4486E662.5080900@redhat.com> <20060607151754.GB23954@fieldses.org> <4486F020.3030707@redhat.com> Content-Type: text/plain Date: Wed, 07 Jun 2006 11:39:02 -0400 Message-Id: <1149694742.26188.6.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit X-UiO-Spam-info: not spam, SpamAssassin (score=-3.806, required 12, autolearn=disabled, AWL 1.19, UIO_MAIL_IS_INTERNAL -5.00) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2006-06-07 at 11:26 -0400, Peter Staubach wrote: > J. Bruce Fields wrote: > > >On Wed, Jun 07, 2006 at 10:44:50AM -0400, Peter Staubach wrote: > > > > > >>I saw that wording too and assumed what I think that you assumed. I > >>assumed that that meant that if the new size is equal to the old size, > >>then nothing should be changed. However, that does not seem to be how > >>those words are to be interpreted. They are to be interpreted as "if > >>the new length of the file can be successfully set, then the > >>mtime/ctime should be changed". > >> > >> > > > >What's the basis for that interpretation? The language seems extremely > >clear: > > > > "On successful completion, if the file size is changed, these > > functions will mark for update the st_ctime and st_mtime fields > > of the file, and if the file is a regular file, the S_ISUID and > > S_ISGID bits of the file mode may be cleared." > > > >Why are you concerned about this? Do you have an actual application > >that breaks? > > > > Yes, there is a customer who is quite unhappy that the semantics over Linux > client NFS are different than those of BSD, Solaris, and local file system > access on Linux itself. The basis for my work is based on a bugzilla from > this customer. > > My interpretation is based on looking at the local behavior on Linux, which > changes mtime/ctime even if the file size does not change, and SunOS, which > changes mtime/ctime even if the file size does not change and is very > heavily SUSv3 compliant. > > In this case, "changed" does not mean "made different". It simply means > that the file size is set to the new value. > > I would have chosen different words or a different interpretation too, > but all of the evidence suggests that the semantics are as I stated. We've already fixed this to be SuSv3 compliant for both create and truncate. Your "safe" suggestion would break truncate again. That is why it is being vetoed. Cheers, Trond