From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41942) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WGSIP-0002Ex-K2 for qemu-devel@nongnu.org; Thu, 20 Feb 2014 07:00:11 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WGSIJ-0001pk-FZ for qemu-devel@nongnu.org; Thu, 20 Feb 2014 07:00:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:21707) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WGSIJ-0001pS-7w for qemu-devel@nongnu.org; Thu, 20 Feb 2014 06:59:59 -0500 Date: Thu, 20 Feb 2014 06:59:51 -0500 From: Jeff Cody Message-ID: <20140220115951.GC30664@localhost.localdomain> References: <1392817351-22148-1-git-send-email-famz@redhat.com> <1392817351-22148-7-git-send-email-famz@redhat.com> <20140219211732.GB4059@localhost.localdomain> <20140220050138.GC6744@T430.redhat.com> <20140220050800.GC4059@localhost.localdomain> <20140220082856.GD6744@T430.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140220082856.GD6744@T430.redhat.com> Subject: Re: [Qemu-devel] [PATCH v14 06/14] block: Add backing_blocker in BlockDriverState List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: kwolf@redhat.com, benoit.canet@irqsave.net, rjones@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com, imain@redhat.com, stefanha@redhat.com, pbonzini@redhat.com On Thu, Feb 20, 2014 at 04:28:56PM +0800, Fam Zheng wrote: > On Thu, 02/20 00:08, Jeff Cody wrote: > > On Thu, Feb 20, 2014 at 01:01:38PM +0800, Fam Zheng wrote: > > > On Wed, 02/19 16:17, Jeff Cody wrote: > > > > On Wed, Feb 19, 2014 at 09:42:23PM +0800, Fam Zheng wrote: > > > > > This makes use of op_blocker and blocks all the operations except for > > > > > commit target, on each BlockDriverState->backing_hd. > > > > > > > > > > The asserts for op_blocker in bdrv_swap are removed because with this > > > > > change, the target of block commit has at least the backing blocker of > > > > > its child, so the assertion is not true. Callers should do their check. > > > > > > > > > > Signed-off-by: Fam Zheng > > > > > --- > > > > > block.c | 19 +++++++++++++++---- > > > > > include/block/block_int.h | 3 +++ > > > > > 2 files changed, 18 insertions(+), 4 deletions(-) > > > > > > > > > > diff --git a/block.c b/block.c > > > > > index dec44d4..95d8c1f 100644 > > > > > --- a/block.c > > > > > +++ b/block.c > > > > > @@ -1044,19 +1044,33 @@ fail: > > > > > void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd) > > > > > { > > > > > if (bs->backing_hd) { > > > > > + assert(error_is_set(&bs->backing_blocker)); > > > > > > > > When I run block-commit, on either the active or non-active layer, I > > > > get an assertion here. The qemu-iotests do not catch it, and I > > > > presume it is because happens a couple of seconds or so after the > > > > success message is returned over QMP. > > > > > > > > > > I can't reproduce this, could you give some specific steps? Thanks. > > > > > > > Sure - I am guessing the key is performing some live block snapshots > > first. Here is what I did (this is from memory, but I think the steps > > are right): > > > > Nothing special really about the cmdline: > > qemu-system-x86_64 -drive file=/home/jtc/test.qcow2,if=virtio -qmp stdio ... > > > > The QMP commands: > > > > For the non-active layer case: > > > > { "execute": "qmp_capabilities" } > > { "execute": "blockdev-snapshot-sync", "arguments": { "device": "virtio0","snapshot-file":"/tmp/snap1.qcow2","format": "qcow2" } } > > { "execute": "blockdev-snapshot-sync", "arguments": { "device": "virtio0","snapshot-file":"/tmp/snap2.qcow2","format": "qcow2" } } > > { "execute": "block-commit", "arguments": { "device": "virtio0", "top": "/tmp/snap1.qcow2" } } > > > > > > For the active layer case (I think I still had 2 snapshots here, not > > entirely positive): > > > > { "execute": "qmp_capabilities" } > > { "execute": "blockdev-snapshot-sync", "arguments": { "device": "virtio0","snapshot-file":"/tmp/snap1.qcow2","format": "qcow2" } } > > { "execute": "blockdev-snapshot-sync", "arguments": { "device": "virtio0","snapshot-file":"/tmp/snap2.qcow2","format": "qcow2" } } > > { "execute": "block-commit", "arguments": { "device": "virtio0", "top": "/tmp/snap2.qcow2" } } > > { "execute": "block-job-complete", "arguments": { "device": "virtio0" }} > > > > Yes. I forgot to use bdrv_set_backing_hd in bdrv_append. > > Could you try if the below patch fixes it? Thanks. > Yep, this seems to fix it. > Fam > > --- > > diff --git a/block.c b/block.c > index 1af43b9..66a8e35 100644 > --- a/block.c > +++ b/block.c > @@ -1978,7 +1978,7 @@ void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top) > > /* The contents of 'tmp' will become bs_top, as we are > * swapping bs_new and bs_top contents. */ > - bs_top->backing_hd = bs_new; > + bdrv_set_backing_hd(bs_top, bs_new); > bs_top->open_flags &= ~BDRV_O_NO_BACKING; > pstrcpy(bs_top->backing_file, sizeof(bs_top->backing_file), > bs_new->filename);