From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <52F8DE52.1080805@redhat.com> Date: Mon, 10 Feb 2014 15:12:34 +0100 From: Peter Rajnoha MIME-Version: 1.0 References: <20140123142700.315e2d3f@leda.localdomain> <20140204095544.65cad0f2@leda.localdomain> <52F1198B.8000706@redhat.com> <20140207141420.54239977@leda.localdomain> <20140208003607.503a44c9@leda.localdomain> <20140208005550.6b7e134d@leda.localdomain> <52F88ED0.8030201@redhat.com> <20140210103056.2f2a950f@leda.localdomain> <52F8C3FC.6000302@redhat.com> <20140210144821.65cf1a19@leda.localdomain> In-Reply-To: <20140210144821.65cf1a19@leda.localdomain> Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] blkid_wiping breaks snapshots Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development Cc: list@eworm.de, zkabelac@redhat.com On 02/10/2014 02:48 PM, Christian Hesse wrote: > Zdenek Kabelac on Mon, 2014/02/10 13:20: >> Dne 10.2.2014 10:30, Christian Hesse napsal(a): >>> Zdenek Kabelac on Mon, 2014/02/10 09:33: >>>> Dne 8.2.2014 00:55, Christian Hesse napsal(a): >>>>> Christian Hesse on Sat, 2014/02/08 00:36: >>>>>> Hello everybody, >>>>>> >>>>>> I think I nailed it down with git bisect. My first bad commit is: >>>>>> >>>>>> 75628f341ad38b68aae33eae0b5700be2a6e5769 >>>>>> configure: enable blkid_wiping by default if the blkid library is >>>>>> present >>>>>> >>>>>> Looks like this wipes data that is still needed... Building a package >>>>>> with '--disable-blkid_wipe' now to verify on another system. >>>>> >>>>> Uh, this only helps part of... >>>>> >>>>> I changed my test setup and used writable snapshots. After that I got: >>>>> >>>>> WARNING: DM_snapshot_cow signature detected on /dev/cvg/snap-home at >>>>> offset 0. Wipe it? [y/n] >>>>> >>>>> (see https://bbs.archlinux.org/viewtopic.php?id=176504 for another >>>>> report) >>>>> >>>>> Looks like disabling blkid_wiping fixes this. My snapshot corruption >>>>> still occurs though. :-/ >>>>> Bad thing about it is that the corruption does not occur reliable when >>>>> doing simple tests in 'git bisect'... Out of ideas for now - Will go to >>>>> bed now. >>>> >>>> Now this was helpful, I guess I think what is going on. >>> >>> Great! Waiting for patches then. :D >>> >>> I could provide some more information when needed: >>> >>> * This happens with read only snapshots only. >>> * I could reproduce with commit eaa23d32732c9bc3dd4f948781b5764cf21d84ba >>> (wiping: add support for blkid wiping), so it was introduced there or >>> before. >>> >>> Should I investigate further or wait for something to test from you? >> >> Is the patch bellow fixing your problem ? >> (It's still not final - but should help) >> >> Zdenek >> >> >> diff --git a/tools/lvcreate.c b/tools/lvcreate.c >> index 638a868..e8b1a7f 100644 >> --- a/tools/lvcreate.c >> +++ b/tools/lvcreate.c >> @@ -772,7 +772,7 @@ static int _read_activation_params(struct >> lvcreate_params *lp, LVM_READ | LVM_WRITE); >> >> /* Must not zero/wipe read only volume */ >> - if (!(lp->permission & LVM_WRITE)) { >> + if (!lp->snapshot && !(lp->permission & LVM_WRITE)) { >> lp->zero = 0; >> lp->wipe_signatures = 0; >> } > > This looks good to me. I've made some backups now without any corruption. > > But with blkid_wiping enabled I do have this warning/question now for read > only snapshots as well: > > WARNING: DM_snapshot_cow signature detected on /dev/cvg/snap-home > at offset 0. Wipe it? [y/n] > > lvm works perfectly only with your patch applied and compiled with > --disable-blkid_wiping. Also, try this patch in addition: https://git.fedorahosted.org/cgit/lvm2.git/commit/?id=ed166a3b1d3290ad887d8f83c24a8d8877713d3c -- Peter