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

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Fri, Jul 18, 2014 at 04:17:02PM -0400, annie li wrote:
> 
> 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?

Yes :-)
> 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?

Heh.
> 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.

In both cases dom0 is part of the equation. In one
case it is the destination and in another it is the source - both cases
for the same page right?

> 
> Thanks
> Annie
> >
> >
> >_______________________________________________
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> >Xen-devel@xxxxxxxxxxxxx
> >http://lists.xen.org/xen-devel
> 

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