Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752737AbaFBPbr (ORCPT ); Mon, 2 Jun 2014 11:31:47 -0400 Received: from imap.thunk.org ([74.207.234.97]:45729 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752132AbaFBPbn (ORCPT ); Mon, 2 Jun 2014 11:31:43 -0400 Date: Mon, 2 Jun 2014 11:31:24 -0400 From: "Theodore Ts'o" To: Chuck Lever Cc: Arnd Bergmann , Nicolas Pitre , "H. Peter Anvin" , Dave Chinner , LKML Kernel , linux-arch@vger.kernel.org, joseph@codesourcery.com, john.stultz@linaro.org, Christoph Hellwig , tglx@linutronix.de, geert@linux-m68k.org, lftan@altera.com, linux-fsdevel , xfs@oss.sgi.com, Linux NFS Mailing List Subject: Re: [RFC 11/32] xfs: convert to struct inode_time Message-ID: <20140602153124.GH30598@thunk.org> Mail-Followup-To: Theodore Ts'o , Chuck Lever , Arnd Bergmann , Nicolas Pitre , "H. Peter Anvin" , Dave Chinner , LKML Kernel , linux-arch@vger.kernel.org, joseph@codesourcery.com, john.stultz@linaro.org, Christoph Hellwig , tglx@linutronix.de, geert@linux-m68k.org, lftan@altera.com, linux-fsdevel , xfs@oss.sgi.com, Linux NFS Mailing List References: <1401480116-1973111-1-git-send-email-arnd@arndb.de> <8618458.1EVJCoVbkH@wuerfel> <4178301.j9kWdGCRLC@wuerfel> <6868F108-F0B2-423F-AE31-90DF86A5B7DD@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6868F108-F0B2-423F-AE31-90DF86A5B7DD@oracle.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 02, 2014 at 11:04:23AM -0400, Chuck Lever wrote: > I’m wondering what should be done about NFS. A solution for NFS should > match any scheme that is considered for local file systems, IMO. > > An alternative would be to “cap” the timestamps transmitted via NFSv3 by > Linux, so that a pre-epoch timestamp is transmitted as zero, and a large > timestamp is transmitted as UINT_MAX. I wonder if it would make sense to try to promulgate via the Austin group, and possibly the C standards committee the concept of a bit pattern (that might commonly be INT_MAX or UINT_MAX) that means "time unknown", or "time indefinite" or "we couldn't encode the time". We would then teach gmtime(3) and asctime(3) to print some appropriate message, and we could teach programs like find (with the -mtime) option, make, tmpwatch, et. al., that they can't make any presumption about the comparibility of any timestamp which has a value of TIME_UNDEFINIED. It would be problematic for time(2) or gettimeofday(2) to return TIME_UNDEFINED, since there are programs that care about time ticking forward, but I could imagine a new interface which would be permitted to return a flag indicating that we don't know the current time (because the CMOS battery had run down, etc.) so instead we're going to be counting the number of seconds since the system was booted. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/