From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas McClendon Subject: Re: DM_snapshot_cow filesystem (dmsetup create snapshot) Date: Thu, 01 Dec 2011 14:26:14 -0600 Message-ID: <4ED7E2E6.1010100@filteredperception.org> References: <20111029204947.GU23336@agk-dp.fab.redhat.com> <4ED2DF0F.1070108@filteredperception.org> <4ED59040.50406@filteredperception.org> <20111130220259.GA7595@agk-dp.fab.redhat.com> <4ED6BD81.4090609@filteredperception.org> <20111201141236.GB7595@agk-dp.fab.redhat.com> <4ED7E11D.1090904@filteredperception.org> <20111201202029.GC7595@agk-dp.fab.redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20111201202029.GC7595@agk-dp.fab.redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: dm-devel@redhat.com List-Id: dm-devel.ids On 12/01/2011 02:20 PM, Alasdair G Kergon wrote: > On Thu, Dec 01, 2011 at 02:18:37PM -0600, Douglas McClendon wrote: >> The overlay device in this situation is a read-write tmpfile in tmpfs, >> looped to be available as the dm-snapshot 'snapshot/overlay device'. > > Ah - well if your base device is already read-only, then there is no > corruption and you should be able to edit the bit of the disk image > that says 'this image is invalid' and recover it read-only or extend it. Can I get a commandline that summarizes how to do that 'edit'? -dmc