From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:50409 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753057AbdHWGTd (ORCPT ); Wed, 23 Aug 2017 02:19:33 -0400 Date: Tue, 22 Aug 2017 23:19:31 -0700 From: Christoph Hellwig Subject: Re: Support for data CRC Message-ID: <20170823061931.GA30488@infradead.org> References: <20170821190414.long2535xppcxvvd@breakpoint.cc> <20170821230232.GS10621@dastard> <20170822055136.GA2697@infradead.org> <20170822111322.jt66qlzvalsiju6n@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170822111322.jt66qlzvalsiju6n@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 Tue, Aug 22, 2017 at 01:13:22PM +0200, Sebastian Andrzej Siewior wrote: > copy on write. So the data crc is dead / not possible / not wanted or > part of copy on write? We support copy on write (or redirect on write to be correct) now 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 first if we really want the feature, and then where to place the checksum (extent structure, rmap, ?).