Porting the block-iscsi hotplug script

[Gustau Pérez]

> Linux already has some code to do this checking, but this also involves 
> taking a lock in order to make sure there's only one hotplug script 
> performing this check at the same time.
>
> The Linux function that performs this checking is in:
>
> http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=tools/hotplug/Linux/block;h=2691b56951c9b82094471a141b9e0bed04abb929;hb=HEAD#l40
>
> And the caller is:
>
> http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=tools/hotplug/Linux/block;h=2691b56951c9b82094471a141b9e0bed04abb929;hb=HEAD#l275
>
> If you take a look, the call to check_device_sharing is protected with the 
> "block" lock.
>


  Hi,

  finally $WORK gave me a few time to spend and I managed to have
something that works with 'sh' (ash). It'd need some comments here and
there, but it works. I'll post the scripts somewhere when I got time, or
would you prefer diff?

  Next step would be to deal with HVM domains and qemu, right?

  Gustau