[libvirt] [Patch] Libvirt - Fix locking for readonly devices

[Eric Blake]

On 05/08/2012 03:41 AM, David Weber wrote:
> Hi,
> 
> I'm currently working on getting sanlock into Debian/Ubuntu.
> While testing, I noticed that I wasn't able to add a readonly 
> or shared device: "internal error unsupported 
> configuration: Readonly leases are not supported".
> 
> After looking into the source, it seems to be the following
> situation:
> - Libvirt passes every device to the sanlock plugin, even if
> it is readonly
> - The sanlock plugin rejects to add a lease for the readonly
> device, returning an error so the machine starts to fail
> 
> The attached patch rejects passing readonly and shared devices 
> to the lock-plugin so they shouldn't be a problem anymore.
> 
> Would this be an appropriated way to fix this problem? (I'm 
> neither experienced in libvirt nor C)

I'm not sure what the best fix is.  I think that the lock manager
protocol is set up to allow for a shared lease, and that a readonly or
shared disk should use a shared instead of an exclusive lease.
Hopefully Dan Berrange can chime in.

> 
> What seems odd to me is that Fedora either doesn't hit this
> or nobody has ever reported it.
> 
> I'm not member of this list so please CC me.

Thankfully, list policy is to reply-to-all.

-- 
Eric Blake   eblake at redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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