Re: [PATCH 2/2] libxl: do not automatically force detach of block devices

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Wei Liu writes ("Re: [PATCH 2/2] libxl: do not automatically force detach of 
block devices"):
> On Mon, Sep 14, 2020 at 12:41:09PM +0200, Roger Pau Monné wrote:
> > Maybe a new function should be introduced instead, that attempts to
> > remove a device gracefully and fail otherwise?
> > 
> > Then none of the current APIs would change, and xl could use this new
> > function to handle VBD removal?
> 
> This sounds fine to me.

I agree.

If there is going to be different default policy for different devices
it ought to be in xl, not libxl, but frankly I think this is an
anomaly.

I suggest we have a new entrypoint that specifies the fallback
behaviour explicitly.  ISTM that there are three possible behaviours:
 - fail if the guest does not cooperate
 - fall back to force remove
 - rip the device out immediately

The last of these would be useful only in rare situations.  IDK if the
length of the timeout (for the first two cases) ought to be a
parameter too.

Ian.