Return-Path: Received: from mail-yw0-f194.google.com ([209.85.161.194]:34734 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751531AbcEMO2a convert rfc822-to-8bit (ORCPT ); Fri, 13 May 2016 10:28:30 -0400 MIME-Version: 1.0 In-Reply-To: <4211584.odaTcq8sN6@wuerfel> References: <20160429125736.23636.47874.stgit@warthog.procyon.org.uk> <4211584.odaTcq8sN6@wuerfel> Date: Fri, 13 May 2016 07:28:29 -0700 Message-ID: Subject: Re: [RFC][PATCH 0/6] Enhanced file stat system call From: Richard Sharpe To: Arnd Bergmann Cc: Steve French , David Howells , linux-fsdevel , linux-afs@vger.kernel.org, "linux-nfs@vger.kernel.org" , samba-technical , LKML , "linux-ext4@vger.kernel.org" , Deepa Dinamani Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, May 9, 2016 at 6:09 AM, Arnd Bergmann wrote: > On Thursday 05 May 2016 21:00:18 Steve French wrote: >> On Thu, May 5, 2016 at 5:54 PM, Steve French wrote: >> > On Wed, May 4, 2016 at 8:46 AM, Arnd Bergmann wrote: >> >> On Friday 29 April 2016 13:57:36 David Howells wrote: >> >>> struct statx *buffer); >> >>> >> >>> This is an enhanced file stat function that provides a number of useful >> >>> features, in summary: >> >>> >> >>> (1) More information: creation time, data version number, inode >> >>> generation >> >>> number and flags. A subset of these is available through a number of >> >>> filesystems (such as CIFS, NFS, AFS, Ext4 and BTRFS). >> >>> >> >> >> >> I have a question about birthtime/creationtime: As we are gaining a way >> >> to read this, should we also provide a way to update it using a new >> >> variant >> >> of the utimensat syscall in order to have 'cp -a' create an identical >> >> copy, >> >> or is the idea that this is defined as the time that is particular copy >> >> of the inode was created? >> >> >> >> I've discussed this with Deepa in the past, as she is driving the >> >> convertion of the inode timestamps to timespec64 now, and we will >> >> need a new version of utimensat for her work as well. I can see good >> >> reasons either way (allowing updates of btime or disallowing them). >> > >> It would help interop with Windows (and presumably Mac) if birth time can be >> updated > > Ok, thanks. That is certainly a good reason in favor. > > If nothing else comes up, I guess we can prepare a patch for a new > utimensat variant to do this and wait for more comments on that. > > Arnd Isn't there also a strong case for a setattr call that allows us to atomically set a collection of attributes from userspace? It would seem that network file systems (the clients) could use such features. -- Regards, Richard Sharpe (何以解憂？唯有杜康。--曹操)