[libvirt] [PATCH] Fix reporting of i/o errors by iohelper process

[Jason J. Herne]

On 02/05/2015 11:26 AM, Jason J. Herne wrote:
> Hello Eric,
>
> it has been quite a while since we have looked at this :). I'm
> revisiting this problem and I find that it still exists. Here is an
> archive link of our previous discussions on this:
>
> https://www.redhat.com/archives/libvir-list/2014-July/thread.html#00809
>
> Basically, when I do a migration and run out of disk space I do not see
> a meaningful error message without this patch. Early on in our previous
> discussions you asked me how I had gotten through the
> qemuDomainSaveMemory function without hitting this code:
>
> if (virFileWrapperFdClose(wrapperFd) < 0)
>          goto cleanup;
>
> If qemuMigrationToFile fails we go directly to cleanup and do not pass
> through the virFileWrapperFdClose call. For reference:
>
>      /* Perform the migration */
>      if (qemuMigrationToFile(driver, vm, fd, offset, path,
>                              qemuCompressProgramName(compressed),
>                              bypassSecurityDriver,
>                              asyncJob) < 0)
>          goto cleanup;
>
> This is why my patch adds the additional call to virFileWrapperFdClose.
> Perhaps, if we cannot tolerate calling it twice, I can adjust the code
> such that we only call it once.
>
> For some odd reason, you seem to see messages that I do not (take look
> at my final message in the thread linked above). I was not able to see
> your "goodbye world \n" message.
>
> I would be interested to know what you see when you run my test case
> without my patch. If you feel like trying it just create a 50MB disk
> image and loop mount it:
>
>    mount -o loop /usr/local/var/lib/libvirt/qemu/save.img
> /usr/local/var/lib/libvirt/qemu/save
>
> Then:
>      virsh managedsave guestname
>
> And report what you saw on the command line and the libvirtd console
> and/or log depending on how you run the daemon. I suspect (since you saw
> "goodbye world") that you would also see the out of disk space message
> ok. If I'm correct, then the question becomes... why don't I see it too? :)
>
> Thanks for your time.
>

Polite Ping? :)

-- 
-- Jason J. Herne (jjherne at linux.vnet.ibm.com)