From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:43863 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750920AbdIKGhb (ORCPT ); Mon, 11 Sep 2017 02:37:31 -0400 Date: Sun, 10 Sep 2017 23:37:29 -0700 From: Christoph Hellwig Subject: Re: Support for data CRC Message-ID: <20170911063729.GA10489@infradead.org> References: <20170821190414.long2535xppcxvvd@breakpoint.cc> <20170821230232.GS10621@dastard> <20170822055136.GA2697@infradead.org> <20170822111322.jt66qlzvalsiju6n@breakpoint.cc> <20170823061931.GA30488@infradead.org> <20170910195026.7ftxcgmwyri5a5fz@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170910195026.7ftxcgmwyri5a5fz@breakpoint.cc> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Sebastian Andrzej Siewior Cc: Christoph Hellwig , Dave Chinner , linux-xfs@vger.kernel.org On Sun, Sep 10, 2017 at 09:50:27PM +0200, Sebastian Andrzej Siewior wrote: > On 2017-08-22 23:19:31 [-0700], Christoph Hellwig wrote: > > as part of the reflink feature. These out of place writes are > > a requirement to implement data checksums, as otherwise your data > > and checksum can not be updated atomically. Everything else is > > beyond that at this point is vapourware. We'd have to decided > So using the journal for atomic updates doesn't work then. Which means > fragmentation unavoidable. Well, in theory you could also do data journalling - but in the end out of place writes are probably going to be more efficient, and at least for XFS also area already implemented.