Re: [Qemu-devel] [PATCH][RFC] To mount qemu disk image on the host

[Laurent Vivier]

Le vendredi 25 janvier 2008 à 20:52 +0100, Andre Przywara a écrit :
> Laurent Vivier wrote:
> > Le vendredi 25 janvier 2008 à 09:18 -0600, Anthony Liguori a écrit :
> >> Laurent Vivier wrote:
> >>> Hi,
> >>>
> >>> this patch allows to mount qemu disk images on the host.
> >>>   
> > 
> > Sorry, I didn't see you did a similar work 19 months ago.
> >> Note, the general problem with this approach is that mounting a NBD 
> >> device locally with write access can lead to dead locks.  If you look 
> >> through the mailing list archives, you'll find a number of conversations 
> >> on the topic.
> I sometimes ago was also working on a nbd implementation for 
> qcow-images, but I came to the same deadlock conclusion. (At least 
> theoretically, I didn't finish this as I ran first into debugging 
> problems and secondly out of time). But IMHO this only applies to 
> localhost mounts, real network mounting should work (this is actually 

As it seems a problem related to the page cache, perhaps we could open
the QCOW file with O_DIRECT to avoid the problem ?

Laurent
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