Porting the block-iscsi hotplug script

[Roger Pau Monné]

On Thu, 17 Mar 2016, Gustau Pérez wrote: 
> >   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?
> >
> 
>    HI Roger,
> 
>    here [1], [2] there are the first versions of the block and locking
> scripts. Perhaps those scripts need more comments, I don't know. I did
> not have much time these days, that's why it took me a bit.
> 
>    OTOH I'm not sure if there is any xen programming style I needed to
> follow. If so let me know.

Hello,

I've been on vacations last week and I'm trying to catch up with my email 
backlog, sorry for the delay in the reply.

OTOH, George Dunlap from Citrix has posted the series that should enable 
hotplug scripts to work with HVM domains. I need to rebase my FreeBSD 
hotplug script support on top of it, so you can try it. George's series 
can be found at:

http://lists.xenproject.org/archives/html/xen-devel/2016-03/msg02739.html

I will try to rebase my work on top of this and provide you with a git 
branch so you can easily test it.

Regarding your questions about the locking mechanism, I'm not that 
familiar with it, but I'm not sure why a lock array is need. AFAICT only 
one lock should be needed, that prevents multiple hotplug scripts from 
travessing the xenstore disk information at the same time. Please bring 
this question to xen-devel.

> [1] http://pastebin.com/FhaQeuG1
> [2] http://pastebin.com/ZHWKRg5f

LGTM :). You will have to formally submit this as patches when the hotplug 
work is committed to upstream Xen.

Roger.