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Date: Wed, 5 Jun 2013 16:41:24 +0200
From: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20130605144124.GA352@stefanha-thinkpad.muc.redhat.com>
References: <1370421194-27049-1-git-send-email-stefanha@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v2] blockdev: reset werror/rerror on
	drive_del
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To: qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Markus Armbruster <armbru@redhat.com>, dron@redhat.com

On Wed, Jun 05, 2013 at 10:33:14AM +0200, Stefan Hajnoczi wrote:
> Paolo Bonzini <pbonzini@redhat.com> suggested the following test case:
> 
> 1. Launch a guest and wait at the GRUB boot menu:
> 
>   qemu-system-x86_64 -enable-kvm -m 1024 \
>    -drive if=none,cache=none,file=test.img,id=foo,werror=stop,rerror=stop
>    -device virtio-blk-pci,drive=foo,id=virtio0,addr=4
> 
> 2. Hot unplug the device:
> 
>   (qemu) drive_del foo
> 
> 3. Select the first boot menu entry
> 
> Without this patch the guest pauses due to ENOMEDIUM.  The guest is
> stuck in a continuous pause loop since the I/O request is retried and
> fails immediately again when the guest is resumed.
> 
> With this patch the error is reported to the guest.
> 
> Note that this scenario actually happens sometimes during libvirt disk
> hot unplug, where device_del is followed by drive_del.  I/O may still be
> submitted to the drive after drive_del if the guest does not process the
> PCI hot unplug notification.
> 
> Reported-by: Dafna Ron <dron@redhat.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  blockdev.c      | 4 ++++
>  hmp-commands.hx | 2 ++
>  2 files changed, 6 insertions(+)

Applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan