Re: [Qemu-devel] 2.1 unexpected stop after exporting blockdev via nbd server

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Mon, Jan 05, 2015 at 05:12:10PM +0400, Andrey Korolyov wrote:
> On Fri, Jan 2, 2015 at 4:04 PM, Stefan Hajnoczi <stefanha@gmail.com> wrote:
> > On Thu, Dec 18, 2014 at 07:38:59PM +0400, Andrey Korolyov wrote:
> >> 2.1-stable is currently crashing with the
> >>
> >> Co-routine re-entered recursively
> >> 2014-12-16 15:06:23.578+0000: shutting down
> >>
> >> after execution of (for example) following when using virtio-dp as a
> >> disk backend:
> >>
> >> '{ "execute": "nbd-server-start", "arguments": { "addr": { "type":
> >> "inet", "data": { "host": "10.6.0.1", "port": "3333" } } } }'
> >> '{ "execute": "nbd-server-add", "arguments": {"device":
> >> "drive-virtio-disk0","writable": false } }'
> >
> > Hi,
> > You need patches from Max Reitz that make the run-time NBD server
> > support dataplane:
> > f214928 nbd: Follow the BDS' AIO context
> > 3338442 block: Add AIO context notifiers
> > 958c717 nbd: Drop nbd_can_read()
> >
> > Please try QEMU v2.2.0 or qemu.git.
> >
> > Stefan
> 
> Thanks Stefan, those commits are enough to make dataplane drive work
> well with runtime nbd server. By the way, can such functionality
> improvements (not major improvements like discard support for scsi)
> make their way as backports? To reword this, unexpected behavior like
> sudden shutdown I described is better to be closed by later fixes than
> by stubs or left as it currently behaving IMO.

It is a bug that NBD combined with virtio-blk dataplane aborted, it
should have produced an error message and simply refused to start the
NBD server.

Now that QEMU 2.2 stable has been released I'm not sure if additional
2.1.x releases will be made at all.  I have CCed qemu-stabled@nongnu.org
to see if there is interest.

Stefan

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