From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Durgin Subject: Re: Modifying RBD image changes it's snapshot Date: Wed, 26 Jun 2013 14:42:27 -0700 Message-ID: <51CB6043.5020109@inktank.com> References: <1805042.yIbHV06QAO@karol-esprimo-p5925> <51CB2FC6.6070803@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pb0-f48.google.com ([209.85.160.48]:54031 "EHLO mail-pb0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752251Ab3FZVnJ (ORCPT ); Wed, 26 Jun 2013 17:43:09 -0400 Received: by mail-pb0-f48.google.com with SMTP id ma3so14716759pbc.35 for ; Wed, 26 Jun 2013 14:43:09 -0700 (PDT) In-Reply-To: <51CB2FC6.6070803@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Karol Jurak Cc: ceph-devel@vger.kernel.org On 06/26/2013 11:15 AM, Josh Durgin wrote: > On 06/26/2013 05:40 AM, Karol Jurak wrote: >> Hi, >> >> I'm using ceph 0.56.6 and kernel 3.9.7 and it looks like modifying RBD >> image >> also changes it's snapshot. I can reproduce this as follows: >> >> # create and map an image >> rbd create --size 128 test-1 >> rbd map test-1 >> >> # write some data to the image >> dd if=/dev/zero of=/dev/rbd/rbd/test-1 bs=1M count=128 >> >> # create and map a snapshot >> rbd snap create test-1@snap-1 >> rbd map test-1@snap-1 >> >> # verify that image and snapshot are identical >> md5sum /dev/rbd/rbd/test-1 /dev/rbd/rbd/test-1@snap-1 >> fde9e0818281836e4fc0edfede2b8762 /dev/rbd/rbd/test-1 >> fde9e0818281836e4fc0edfede2b8762 /dev/rbd/rbd/test-1@snap-1 >> >> # modify the image >> dd if=/dev/urandom of=/dev/rbd/rbd/test-1 bs=512 count=1 >> >> # compare checksums again >> md5sum /dev/rbd/rbd/test-1 /dev/rbd/rbd/test-1@snap-1 >> 1d942c8a5bc7480cecb945ea0d020eed /dev/rbd/rbd/test-1 >> 1d942c8a5bc7480cecb945ea0d020eed /dev/rbd/rbd/test-1@snap-1 >> >> Checksums are identical although the snapshot isn't supposed to be >> modified. >> > > Just reproduced on 3.10-rc7 as well. It seems the snapshot context > loading is broken for format 1 a t least, since unmapping and mapping > after the snapshot exists still has the same problem. I added > http://tracker.ceph.com/issues/5464 to track this. > > Apparently the regression test for this hasn't been running, or we > would've caught this sooner. There's a fix for this on the stable kernel in the wip-snapc-3.9.y branch of ceph-client.git. Josh