From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Fedyk Subject: Re: precise characterization of ext3 atomicity Date: Thu, 4 Sep 2003 12:12:55 -0700 Message-ID: <20030904191255.GE13676@matchmail.com> References: <3F574A49.7040900@namesys.com> <20030904085537.78c251b3.akpm@osdl.org> <3F576176.3010202@namesys.com> <20030904091256.1dca14a5.akpm@osdl.org> <3F57676E.7010804@namesys.com> <20030904181540.GC13676@matchmail.com> <3F578656.60005@namesys.com> Mime-Version: 1.0 Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com Content-Disposition: inline In-Reply-To: <3F578656.60005@namesys.com> List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Hans Reiser Cc: Andrew Morton , reiserfs-list@namesys.com, linux-kernel@vger.kernel.org On Thu, Sep 04, 2003 at 10:37:10PM +0400, Hans Reiser wrote: > Mike Fedyk wrote: > > >On Thu, Sep 04, 2003 at 08:25:18PM +0400, Hans Reiser wrote: > > > > > >>In data=journal and data=ordered modes ext3 also guarantees that the > >>metadata will be committed atomically with the data they point to. > >>However ext3 does not provide user data atomicity guarantees beyond the > >>scope of a single filesystem disk block (usually 4 kilobytes). If a > >>single write() spans two disk blocks it is possible that a crash partway > >>through the write will result in only one of those blocks appearing in > >>the file after recovery. > >> > >> > > > >And how does reiser4 do this without changing the userspace apps? > > > We don't. We just make the hovercraft, we don't force you to go over > the water..... So by default with no user space modifications, reiser4 will be atomic for each write() call, and ext3 will if it aligns withing a single page. Is that correct? Then you can go on to specify that you can have larger transactions if you make some changes to the userspace apps.