From users-return-4085-daniel=haxx.se@subversion.apache.org Tue Aug 3 15:13:07 2010 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on giant.haxx.se X-Spam-Level: X-Spam-Status: No, score=-4.5 required=3.0 tests=BAYES_00,DS_FRIEND autolearn=ham version=3.3.1 Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by giant.haxx.se (8.14.3/8.14.3/Debian-9.1) with SMTP id o73DD6ZO004407 for ; Tue, 3 Aug 2010 15:13:06 +0200 Received: (qmail 55558 invoked by uid 500); 3 Aug 2010 13:12:55 -0000 Mailing-List: contact users-help@subversion.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Delivered-To: mailing list users@subversion.apache.org Received: (qmail 55547 invoked by uid 99); 3 Aug 2010 13:12:54 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 03 Aug 2010 13:12:54 +0000 X-ASF-Spam-Status: No, hits=-0.7 required=10.0 tests=RCVD_IN_DNSWL_LOW,SPF_PASS Received-SPF: pass (nike.apache.org: local policy) Received: from [192.109.42.8] (HELO einhorn.in-berlin.de) (192.109.42.8) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 03 Aug 2010 13:12:44 +0000 X-Envelope-From: stsp@stsp.name Received: from jack.stsp.name (jack.stsp.name [217.197.84.35]) (authenticated bits=128) by einhorn.in-berlin.de (8.13.6/8.13.6/Debian-1) with ESMTP id o73DCLK0005767 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Tue, 3 Aug 2010 15:12:22 +0200 Received: from jack.stsp.name (stsp@localhost [127.0.0.1]) by jack.stsp.name (8.14.3/8.14.3) with ESMTP id o73DCKRX012201; Tue, 3 Aug 2010 15:12:20 +0200 (CEST) Received: (from stsp@localhost) by jack.stsp.name (8.14.3/8.14.3/Submit) id o73DCJVs024503; Tue, 3 Aug 2010 15:12:19 +0200 (CEST) Date: Tue, 3 Aug 2010 15:12:19 +0200 From: Stefan Sperling To: users@subversion.apache.org, Florian Weimer , Les Mikesell Subject: Re: Support for filesystem snapshots (?) Message-ID: <20100803131219.GB29679@jack.stsp.name> Mail-Followup-To: users@subversion.apache.org, Florian Weimer , Les Mikesell References: <4C56F278.9030904@gmail.com> <6EC02A00CC9F684DAF4AF4084CA84D5F01C40CBC@DRMBX3.winmail.deshaw.com> <20100802175621.GL3967@ted.stsp.name> <6EC02A00CC9F684DAF4AF4084CA84D5F01C40CD7@DRMBX3.winmail.deshaw.com> <20100802202736.GO3967@ted.stsp.name> <6EC02A00CC9F684DAF4AF4084CA84D5F01C40CE1@DRMBX3.winmail.deshaw.com> <4C5730D3.8060507@gmail.com> <82eieg56kn.fsf@mid.bfk.de> <20100803105628.GA29679@jack.stsp.name> <20100803123641.GI7288@prunille.vinc17.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100803123641.GI7288@prunille.vinc17.org> User-Agent: Mutt/1.5.20 (2009-06-14) X-Scanned-By: MIMEDefang_at_IN-Berlin_e.V. on 192.109.42.8 X-Virus-Checked: Checked by ClamAV on apache.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.3.5 (giant.haxx.se [80.67.6.50]); Tue, 03 Aug 2010 15:13:07 +0200 (CEST) X-Friend: Friend On Tue, Aug 03, 2010 at 02:36:41PM +0200, Vincent Lefevre wrote: > On 2010-08-03 12:56:28 +0200, Stefan Sperling wrote: > > On Tue, Aug 03, 2010 at 10:33:28AM +0000, Florian Weimer wrote: > > > Kernel-level buffers are taken into account. Application buffers > > > aren't, the application has to take care of that. But if the > > > Subversion fails to do that, it cannot recover from file system > > > crashes, either, which is arguably a bug in Subversion. > > > > Subversion carefully flushes file buffers after writing revision files. > > What do you mean by "flushes file buffers"? A call to fflush()? > Or a call to sync() or fsync() too? > > Assuming the filesystem is on a remote machine (say, NFS), the > necessary needs to be done on the client side: the NFS server > cannot take into account the kernel-level buffers of the client. Subversion calls apr_file_flush(). What that does on which platform depends on APR (and could theoretically change over time). I'm not sure what else you suggest we should do to avoid the (from my point of view non-existent) bug you were talking about. Stefan