How to allow guest to write on 9p/virtfs shared folder?

How to allow guest to write on 9p/virtfs shared folder?

[Manuel Reimer]

Hello,

today, I upgraded my kernel and I seem to have gotten a new kvm backend 
with this.

Now my guest systems are no longer able to write to the host filesystem.

I share the filesystem using the following command to qemu:

-virtfs 
local,id=fsdev0,path=$SHARED,security_model=passthrough,mount_tag=vmshared

and on guest side (fstab):

vmshared /mnt/vmshared 9p 
rw,comment=systemd.automount,trans=virtio,access=any 0 0

Versions:

$ uname -a
Linux manuelspc 3.11.1-1-ARCH #1 SMP PREEMPT Sat Sep 14 19:30:21 CEST 
2013 x86_64 GNU/Linux
$ qemu-system-x86_64 --version
QEMU emulator version 1.5.2, Copyright (c) 2003-2008 Fabrice Bellard

Can someone please help me to get back my writing permissions?

Thank you in advance

Yours

Manuel

Re: How to allow guest to write on 9p/virtfs shared folder?

[Manuel Reimer]

Hello,

I have to add another problem:

I changed "security_model=passthrough" to "security_model=mapped". This 
seems to give me back write permissions. I would prefer "passthrough", 
just as I did before, but this works as a workaround.

Now, If I try to execute a script from the mounted virtfs, then I get 
the following:

-bash: ./test.pl: /usr/bin/perl: bad interpreter: Numerical result out 
of range

If I call the same with "perl ./test.pl", then anything works. If I copy 
the script to somewhere outside of the mounted virtfs, then I can also 
call the script with "./test.pl". What's going on here?

Thanks in advance

Yours

Manuel

On 09/18/2013 08:20 PM, Manuel Reimer wrote:
> Hello,
>
> today, I upgraded my kernel and I seem to have gotten a new kvm backend
> with this.
>
> Now my guest systems are no longer able to write to the host filesystem.
>
> I share the filesystem using the following command to qemu:
>
> -virtfs
> local,id=fsdev0,path=$SHARED,security_model=passthrough,mount_tag=vmshared
>
> and on guest side (fstab):
>
> vmshared /mnt/vmshared 9p
> rw,comment=systemd.automount,trans=virtio,access=any 0 0
>
> Versions:
>
> $ uname -a
> Linux manuelspc 3.11.1-1-ARCH #1 SMP PREEMPT Sat Sep 14 19:30:21 CEST
> 2013 x86_64 GNU/Linux
> $ qemu-system-x86_64 --version
> QEMU emulator version 1.5.2, Copyright (c) 2003-2008 Fabrice Bellard
>
> Can someone please help me to get back my writing permissions?
>
> Thank you in advance
>
> Yours
>
> Manuel
>
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
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>

Re: How to allow guest to write on 9p/virtfs shared folder?

[Manuel Reimer]

On 09/18/2013 08:34 PM, Manuel Reimer wrote:
> -bash: ./test.pl: /usr/bin/perl: bad interpreter: Numerical result out
> of range

I downgraded the kernel on my system to 3.10.9. This fixed this issue.

So it seems like the "9p" kernel module is broken on Linux 3.11.1.

Can someone point me to the commit, where this was fixed, please?

Thanks in advance.

Greetings,

Manuel

Re: How to allow guest to write on 9p/virtfs shared folder?

[Manuel Reimer]

Hello,

just to be sure I didn't miss important information:

My host system is still running with 3.11.1. I only downgraded the guest 
system to 3.10.9. So only the "guest part" is affected.

I'm running ArchLinux on both systems (host and guest).

Yours

Manuel

On 09/19/2013 07:40 PM, Eric Van Hensbergen wrote:
> Unsure.  Looking at the 3.10-3.12 patches I don't see anything specific
> that I would think map to the problem you are mentioning.  I will try and
> reproduce on my mainline kernel and see what I get.
>
>      -eric
>
>
>
> On Thu, Sep 19, 2013 at 9:39 AM, Manuel Reimer
> <Manuel.Spam@nurfuerspam.de>wrote:
>
>> On 09/18/2013 08:34 PM, Manuel Reimer wrote:
>>
>>> -bash: ./test.pl: /usr/bin/perl: bad interpreter: Numerical result out
>>> of range
>>>
>>
>> I downgraded the kernel on my system to 3.10.9. This fixed this issue.
>>
>> So it seems like the "9p" kernel module is broken on Linux 3.11.1.
>>
>> Can someone point me to the commit, where this was fixed, please?
>>
>> Thanks in advance.
>>
>> Greetings,
>>
>>
>> Manuel
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe kvm" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/**majordomo-info.html<http://vger.kernel.org/majordomo-info.html>
>>
>