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Date: Fri, 22 May 2015 12:54:50 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v6 01/13] block: Add op blocker type
 "device IO"
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To: Wen Congyang <wency@cn.fujitsu.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, qemu-devel@nongnu.org, jcody@redhat.com, armbru@redhat.com, mreitz@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>, amit.shah@redhat.com, pbonzini@redhat.com

On Thu, 05/21 15:32, Fam Zheng wrote:
> On Thu, 05/21 15:06, Wen Congyang wrote:
> > On 05/21/2015 02:42 PM, Fam Zheng wrote:
> > > It blocks device IO.
> > > 
> > > All bdrv_op_block_all/blk_op_block_all callers are taken care of:
> > > 
> > > - virtio_blk_data_plane_create
> > > - virtio_scsi_hotplug
> > > 
> > >   Device creation, unblock it.
> > > 
> > > - bdrv_set_backing_hd
> > > 
> > >   Backing hd is not used by device, so blocking is OK.
> > > 
> > > - backup_start
> > > 
> > >   Blocking target when backup is running, unblock it.
> > 
> > Do you forget it?
> 
> Oh I think the commit log is wrong: the target image is only written to by
> block job, there cannot be a device on it, so it it's similar to
> bdrv_set_backing_hd.

Correction: if it's blockdev-backup, the target could have a device, in that
sense it should be unblocked like block_job_create(). I'll fix it.

Fam