From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60761) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eFfno-0003XN-HR for qemu-devel@nongnu.org; Fri, 17 Nov 2017 07:31:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eFfnn-0001U9-No for qemu-devel@nongnu.org; Fri, 17 Nov 2017 07:31:24 -0500 Date: Fri, 17 Nov 2017 13:30:59 +0100 From: Kevin Wolf Message-ID: <20171117123059.GB4795@localhost.localdomain> References: <20171023092945.54532-1-vsementsov@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171023092945.54532-1-vsementsov@virtuozzo.com> Subject: Re: [Qemu-devel] [PATCH] block/snapshot: dirty all dirty bitmaps on snapshot-switch List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com, eblake@redhat.com, jsnow@redhat.com, famz@redhat.com, den@openvz.org, stefanha@redhat.com Am 23.10.2017 um 11:29 hat Vladimir Sementsov-Ogievskiy geschrieben: > Snapshot-switch actually changes active state of disk so it should > reflect on dirty bitmaps. Otherwise next incremental backup using > these bitmaps will be invalid. > > Signed-off-by: Vladimir Sementsov-Ogievskiy We discussed this quite a while ago, and I'm still not convinced that this approach makes sense. Can you give just one example of a use case where dirtying the whole bitmap while loading a snapshot is the desired behaviour? I think the most useful behaviour would be something where the bitmaps themselves are snapshotted, too. But for the time being, the easiest and safest solution might just be to error out in any snapshot operations if any bitmaps are in use. Kevin