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Re: [libvirt] [PATCH 0/2] qemu: Rework CD/DVD changing

On 05/17/2013 04:07 PM, Michal Privoznik wrote:
> On 17.05.2013 07:47, Li Wei wrote:
>> Hi Michal, Daniel
>> It seems there is something wrong with the 2/2 part of this patchset.
>> When I do an "change-media" command in virsh, it doesn't do any better
>> than before, but even worse(I must to wait 5 secs to see the error).
>> I'm not family with libvirt, just add some log things in the qemu_hotplug.c
>> and found the tray_status never change to open, but with michal's original
>> patch (which do active poll on tray_status), I can do "change-media" successfully
>> every time.
> Yes & no. Thing is - originally we ignored tray status in the guest. So
> in case guest has locked the tray and thus ignored our eject request, we
> have changed the media anyway, resulting in possible I/O errors within
> guest.
> With my patch, we send eject request to the qemu, and actively poll for
> the tray to open. We check for up to 10 times every 200ms. So guest has
> 2 seconds to open the tray. If the guest doesn't eject media and open
> the tray we don't proceed with forcibly changing the media.
> These patches are actually a bug fix for
> https://bugzilla.redhat.com/show_bug.cgi?id=892289

Hmm... I think you misunderstood my meaning(sorry for my pool english),
simply to say, I can get expected behavior by apply patch V1 but not V2.

In V1, we do active poll on qemuMonitorGetBlockInfo(), and in V2 we just
wait for origdisk->tray_status to become VIR_DOMAIN_DISK_TRAY_OPEN but
this never happened.


>> IMHO, there must be some bug in the processing of qemu tray change.
>> Thanks,
>> Wei
>> On 01/25/2013 08:20 PM, Michal Privoznik wrote:
>>> The first patch is bare bug fix (without any bug reported though).
>>> The second is again a bug fix, but not so easy to spot. Basically, when we
>>> change a media, we should issue 'eject' first, then wait until the tray gets
>>> open, after which we can finally issue 'change' command. Even for bare 'eject'
>>> we ought to check status, shouldn't we?
>>> Michal Privoznik (2):
>>>   qemu_monitor: Fix tray-open attribute in query-block
>>>   qemu_hotplug: Rework media changing process
>>>  src/qemu/qemu_hotplug.c      | 51 +++++++++++++++++++++++++++++++++++++++++---
>>>  src/qemu/qemu_monitor_json.c |  2 +-
>>>  src/qemu/qemu_monitor_text.c |  6 +++---
>>>  3 files changed, 52 insertions(+), 7 deletions(-)

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