From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 10 Feb 2014 14:48:21 +0100 From: Christian Hesse Message-ID: <20140210144821.65cf1a19@leda.localdomain> In-Reply-To: <52F8C3FC.6000302@redhat.com> 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> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/VJW+l2goKnKTYqxWcdm86iY"; protocol="application/pgp-signature" 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: To: LVM general discussion and development Cc: zkabelac@redhat.com --Sig_/VJW+l2goKnKTYqxWcdm86iY Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable 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=3D176504 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? >=20 > Is the patch bellow fixing your problem ? > (It's still not final - but should help) >=20 > Zdenek >=20 >=20 > 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); >=20 > /* Must not zero/wipe read only volume */ > - if (!(lp->permission & LVM_WRITE)) { > + if (!lp->snapshot && !(lp->permission & LVM_WRITE)) { > lp->zero =3D 0; > lp->wipe_signatures =3D 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. --=20 main(a){char*c=3D/* Schoene Gruesse */"B?IJj;MEH" "CX:;",b;for(a/* Chris get my mail address: */=3D0;b=3Dc[a+= +];) putchar(b-1/(/* gcc -o sig sig.c && ./sig */b/42*2-3)*42);} --Sig_/VJW+l2goKnKTYqxWcdm86iY Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQEcBAEBAgAGBQJS+NiqAAoJEIlFIdfMgPR2jrMH/0h8rMfVkNW4mJy7EwFoYv/0 35G6X83/93VnjlgyBYFhwe+4u/6zn2eoz0n68qeS7taOJt1Ox0OTUtQK1hOvjcId NgsvJF94sjcvo9a1E+f4G5z6ngxL6Z800sCPuW7BIRAt2/S9OEmmH8yVI7fQT05a JBMsJJ5FpltfS5AZyAwvJCUUQYq27/+UCM/GGPu8A+npKcPq3j/N0qhyDtrDlnBQ 4UbPZ4YK3ZmgspsxgYHqI4b0Y/iNykYtvC/2aoIXcEl1sUzk9VrY03S3AMMZdHW2 vCulQqu0P3yPM4mlZz8g9/DuIHychh/OeKQqFu3V6Z16ZMHWPwn86SWbXmC64iw= =i3Fa -----END PGP SIGNATURE----- --Sig_/VJW+l2goKnKTYqxWcdm86iY--