From: Trond Myklebust Subject: Re: [PATCH 02/18] xstat: Add a pair of system calls to make extended file stats available [ver #6] Date: Thu, 22 Jul 2010 13:16:07 -0400 Message-ID: <1279818967.3621.23.camel@heimdal.trondhjem.org> References: <20100715021709.5544.64506.stgit@warthog.procyon.org.uk> <20100715021712.5544.44845.stgit@warthog.procyon.org.uk> <30448.1279800887@redhat.com> <20100722162712.GB10352@jeremy-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Linus Torvalds , Jeremy Allison , Volker.Lendecke@sernet.de, David Howells , linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, samba-technical@lists.samba.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org To: Jan Engelhardt Return-path: Received: from mail-out1.uio.no ([129.240.10.57]:52171 "EHLO mail-out1.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751260Ab0GVRQc (ORCPT ); Thu, 22 Jul 2010 13:16:32 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, 2010-07-22 at 19:03 +0200, Jan Engelhardt wrote: > On Thursday 2010-07-22 18:40, Linus Torvalds wrote: > > >On Thu, Jul 22, 2010 at 9:27 AM, Jeremy Allison wrote: > >> On Thu, Jul 22, 2010 at 08:47:46AM -0700, Linus Torvalds wrote: > >>> Tell me why we shouldn't just do this right? > >> > >> No, ctime isn't the same as Windows "create time". > > > >Umm. What kind of reading problems do you guys have? > > > >I know effin well that ctime isn't the same as Windows create time. > >THAT WAS MY POINT. > > > >But the fact is, th Unix ctime semantics are insane and largely > >useless. There's a damn good reason almost nobody uses ctime under > >unix. > > I beg to differ. ctime is not completely useless. It reflects changes on > the inode for when you don't you change the content. It's like an mtime > for the metadata. It comes useful when you go around in your filesystem > trying to figure out who of your co-admins screwed up the permissions on > /etc/passwd... and if the mtime is the same as that of the last backup, > I can at least have a reasonable assurance that it was /only/ the > metadata that was tampered with. (SHA1 check, yeah yeah, costly on large > files.) Errr... Only if you eliminate utimes() from your syscall table. Otherwise it is trivial to reset the mtime after changing the file contents. Cheers Trond