From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Andreas Dilger Message-Id: <200012260752.eBQ7qea25647@webber.adilger.net> In-Reply-To: <20001226001600.A24447@caldera.de> "from Christoph Hellwig at Dec 26, 2000 00:16:00 am" Date: Tue, 26 Dec 2000 00:52:40 -0700 (MST) MIME-Version: 1.0 Subject: [linux-lvm] Re: [lvm-devel] [PATCH] IOPv6 support for Linux 2.4.0-test13-pre4 (LVM 0.9) Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lvm-devel@sistina.com Cc: linux-lvm@sistina.com Christoph Hellwig writes: > this patch (against Linux 2.4.0-test13-pre4 + my both previous patches), > implements a IOPv6 compatiblity layer for LVM 0.9. This is done by doing > structure conversion in copy_{pv,vg,lv}_{from,to}_user routines that replace > copy_{from,to}_user calls in lvm.c. First of all, I'm not 100% convinced that it is possible to use the IOPv6 user tools with an IOPv10 kernel. Surely there is _something_ that the kernel is expecting that the older tools don't handle? Otherwise, why would the IOP version have changed? Even so, I think doing the compatibility in the kernel is the wrong place - the compatibility bloat should be in the user-space library. I'd rather the compatibility layer was in liblvm (user space) and that the 0.9 user tools could optionally work with an IOPv6 kernel. This would require that users always have the latest tools (which is always the case), but that they could upgrade the tools _before_ upgrading the kernel. Actually, I have no idea yet how hard it is to handle multiple IOP versions from a single liblvm, but I think the "wrapper" method is pretty flexible for a lot less work - it allows us to handle multiple IOP versions at the same time, and also lets you delete older IOP support when you no longer need it. Cheers, Andreas PS - yes I hate it when I complain about work that someone else has done when I'm not quite ready to do a better job myself. -- Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto, \ would they cancel out, leaving him still hungry?" http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert