From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q9QKTkYJ254610 for ; Fri, 26 Oct 2012 15:29:46 -0500 Date: Fri, 26 Oct 2012 15:31:29 -0500 From: Ben Myers Subject: Re: [PATCH] xfsdump: Revert dump version bump for 32bit projid fix Message-ID: <20121026203129.GA405@sgi.com> References: <5085AB70.2060904@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5085AB70.2060904@redhat.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Eric Sandeen Cc: xfs-oss Hey Eric, On Mon, Oct 22, 2012 at 03:24:16PM -0500, Eric Sandeen wrote: > commit 1e309da7a4f7e2a2f456bf6b7cea4c5f1181cd36 fixed xfsdump to > properly save & restore the top 16 bits of a 32-bit projid, which > otherwise was being dropped (and restored as 0) in older xfsdump. > > The original thought was to bump the dump version, so that we know > whether the dump (may) have the top 16 bits filled in. In practice > this would prevent older restores from restoring newer dumps, and > losing the top 16 bits contained in these newer dumps. > > However, in hindsight this appears to be of limited value. I > propose that the dump version change is unuseful/unwanted for a > couple reasons: > > * There is no actual dump *format* change; the structure size > is the same, and the top 16 bits were properly zeroed before; old > restores will read these fixed dumps without problems and without > restoring garbage. IOW, they will behave exactly as buggily as > they did before. And worst case, if a dump containing the top 16 > bits is mangled by an old restore, this can be easily remedied by > simply re-restoring with updated userspace. > > * We have no reliable method to know whether 32 bit project IDs are > in use; the feature flag was not added to the GEOM call at the time > of implementation. Therefore we cannot reliably bump to V4 only > for projid32bit filesystems, and we cannot restrict V4 restores > only to projid32bit filesystems. So the dump version is not > useful for feature cross-checking purposes. > > I spoke with wkendall via email, and although he may not have given > it the most scrutiny (having moved on from xfsdump-land), he also > felt that a version dump may not be warranted. > > Signed-off-by: Eric Sandeen Pulled this into git://oss.sgi.com/xfs/cmds/xfsdump.git, master branch. Regards, Ben _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs