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Date: Thu, 26 Feb 2015 08:59:57 -0500
From: Max Reitz <mreitz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v3 05/11] block: Move BDS close notifiers
 into BB
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To: Fam Zheng <famz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, qemu-devel@nongnu.org, Markus Armbruster <armbru@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>

On 2015-02-25 at 21:19, Fam Zheng wrote:
> On Wed, 02/25 09:12, Max Reitz wrote:
>> Because I need a Notifier pointer to give to
>> blk_add_{insert,remove}_bs_notifier(), and most importantly because the only
>> "opaque" object the callbacks will receive is that Notifier pointer (which
>> in this case is actually a DataPlaneBlkChangeNotifier pointer). I cannot
>> influence the @data parameter, and I cannot (easily) identify the
>> VirtIOBlockDataPlane object from the BlockBackend (which is @data) alone.
> Probably like this:
>
>      struct VirtIOBlockDataPlane {
>          ...
>          Notifier insert_notifier, remove_notifier;
>          ...
>      };
>
>      static void data_plane_blk_insert_notifier(Notifier *n, void *data)
>      {
>          VirtIOBlockDataPlane *s = container_of(n, VirtIOBlockDataPlane, insert_notifier);
>          assert(s->conf->conf.blk == data);
>          data_plane_set_up_op_blockers(s);
>      }
>
>      void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
>                                        VirtIOBlockDataPlane **dataplane,
>      {
>          ...
>          s->insert_notifier.notify = data_plane_blk_insert_notifier;
>          blk_add_insert_bs_notifier(conf->conf.blk, &s->insert_notifier);
>          ...
>      }
>
> ?

Oh, right, thanks!

>> Won't virtio_scsi_hotunplug() (which frees s->{insert,remove}_notifier) be
>> called before a second device is plugged?
>>
> No, multiple SCSIDevice objects (scsi-disk, scsi-generic, etc...) can be
> attached to the same virtio-scsi bus.

You're right, I'll see to it.

Thanks,

Max