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Date: Thu, 1 Sep 2011 13:19:54 -0300
From: Luiz Capitulino <lcapitulino@redhat.com>
Message-ID: <20110901131954.25e81235@doriath>
In-Reply-To: <1314887471-18052-1-git-send-email-kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 0/3] qcow2/coroutine fixes
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To: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-devel@nongnu.org

On Thu,  1 Sep 2011 16:31:08 +0200
Kevin Wolf <kwolf@redhat.com> wrote:

> This fixes a couple of issues with the coroutine-based block layer regarding
> error handling.
> 
> Luiz, can you please try if this fixes your bug?

It fixes the reported bug, but it seems that there's another issue.

I'll copy & paste the test case here for our convenience:

 1. Create a 100MB logical volume and create a 200MB qcow2 image on it
 2. Run qemu with the following command-line:

   # qemu -drive file=disks/test.img,if=virtio,cache=writeback,aio=native \
          -drive file=/dev/vg_doriath/kvmtest,if=virtio -enable-kvm -m 1G \
          -monitor stdio -netdev type=tap,id=guest0,script=qemu-ifup-switch \
          -device virtio-net-pci,netdev=guest0 -cpu host

 3. Log into the guest and run dd to write 150MB on /dev/vdb
 4. The VM will stop
 5. Assign extra space to the logical volume, say 200MB
 6. Type 'cont' in the monitor

If I assign chunks of 50MB each time the VM stop in steps 4 and 5,
I have to do it several times (totalizing a logical volume size of 400MB),
so that dd is able to finish.

Testing with commit b96e92470 works as expected, I extend the lv twice
with 50MB (totalizing 200MB) and dd finishes normally.

Small note: I'm writing 157MB in step 3.