Re: [Xen-devel] Rebooting domu fails in nfs share exported from another domu on the same dom0

[annie li <annie.li@xxxxxxxxxx>]

On 2014/7/18 15:43, Konrad Rzeszutek Wilk wrote:
> On Fri, Jul 18, 2014 at 03:31:43PM -0400, annie li wrote:
> > On 2014/7/18 14:53, Konrad Rzeszutek Wilk wrote:
> > > On Thu, Jul 17, 2014 at 12:56:12PM -0400, annie li wrote:
> > > > On 2014/7/17 11:49, Roger Pau Monné wrote:
> > > > > On 16/07/14 22:36, annie li wrote:
> > > > > > Hi
> > > > > >
> > > > > > I hit a problem in such scenario: vm1 is running and export nfs service,
> > > > > > dom0 mount this nfs, and vm2 is booted in this nfs location. vm1 and vm2
> > > > > > are running on the same dom0.
> > > > > >
> > > > > > When this bug happens, the data flow is:  vm2 blkfront-> vm2 blkback->
> > > I am a bit confused here. 'vm2 blkfront -> vm2 blkback'? Did you
> > > mean 'dom0 blkback'?
> > Yes, Dom0 blkback.
> >
> > > > > > loop -> nfs file -> nfs client -> bridge priv1 -> vm1 vif -> vm1 netback
> > > > > > -> vm1 netfront.
> > > So both netback and netfront run in the same guest? I think you
> > > want these two swapped around (netfront -> netback).
> > No, the netfront in above routine means the one in guest vm1, and this is
> > network RX path in vm1.
> OK, so 'dom0 netback' then. As the netback thread is running in the
> initial domain?
Netback thread is running in Dom0 as normal, and the two vms are all 
normal vm, not driver domain. Probably my initial description causes 
some confusion.
> So a revised view is:
>
>    vm2 blkfront -> dom0 blkback -> loop -> nfs file -> nfs client
>         -> bridge priv1 -> vm1 vif -> dom0 netback -> vm1 netfront
>
> So with the grant map (blkfront -> blkback) the source is dom0
> and the destination is vm1.
You mean destination is vm2 here, right?
But I am little confused. Blkfront of vm2 sends out request to blkback, 
and the data page is allocated from vm2. So the grant map source is vm2, 
destination is dom0. Anything I missed here?
>   For the grant copy, the source is
> dom0 and the destinatation is vm2 right? (or did I get my src
> and dst confused?).
You mean vm1 here, right?
If so, yes, source is dom0, and destination is vm1.
In grantcopy code, it checks whether the source is from dom0, if not, 
then an error is thrown out. In this situation, the source is from vm2 
which is grant mapped.
Thanks
Annie
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