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* Please reconsider bug 26
@ 2016-05-11 14:51 Sébastien Chaumat
  2016-05-12 15:33 ` Wei Liu
  0 siblings, 1 reply; 2+ messages in thread
From: Sébastien Chaumat @ 2016-05-11 14:51 UTC (permalink / raw)
  To: xen-devel


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Hello,

  http://bugs.xenproject.org/xen/bug/26 is nearly 3yrs old.

(bassically one can attach the same vbd rw to 2 domUs with xl without
warning )

 Combined with a distribution behavior  like

https://bugs.launchpad.net/ubuntu/+source/xen/+bug/1572446

 (a trailing domu.cfg~ backup file will be blindly used to launch twice a
domU config with only the name changed)

 leads to real fun  (namely filesystem corruption)

 Recalling early discussion here about xen philosophy, isolation  accross
domUs should be the default. Clearly xl does not provide vbd isolation by
default.

 Would you mind considering implementing vbd usage detection in xl ?

Thanks,
Sebastien

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* Re: Please reconsider bug 26
  2016-05-11 14:51 Please reconsider bug 26 Sébastien Chaumat
@ 2016-05-12 15:33 ` Wei Liu
  0 siblings, 0 replies; 2+ messages in thread
From: Wei Liu @ 2016-05-12 15:33 UTC (permalink / raw)
  To: Sébastien Chaumat; +Cc: Wei Liu, xen-devel

Hello

On Wed, May 11, 2016 at 04:51:41PM +0200, Sébastien Chaumat wrote:
> Hello,
> 
>   http://bugs.xenproject.org/xen/bug/26 is nearly 3yrs old.
> 
> (bassically one can attach the same vbd rw to 2 domUs with xl without
> warning )
> 
>  Combined with a distribution behavior  like
> 
> https://bugs.launchpad.net/ubuntu/+source/xen/+bug/1572446
> 
>  (a trailing domu.cfg~ backup file will be blindly used to launch twice a
> domU config with only the name changed)
> 
>  leads to real fun  (namely filesystem corruption)
> 
>  Recalling early discussion here about xen philosophy, isolation  accross
> domUs should be the default. Clearly xl does not provide vbd isolation by
> default.
> 
>  Would you mind considering implementing vbd usage detection in xl ?
> 

I think xen 4.7 (which to be released soon) should fix one aspect of the
issue. Toolstack won't be able to attach same vbds twice.

And looking at the block script for Linux, it does check for "!".

Are you able to test one of the RCs (latest one RC2) for xen 4.7 to see
if it fixes the bug?

Unfortunately the fixes might be too complicated to backport.

Wei.


> Thanks,
> Sebastien

> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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