Re: [Qemu-devel] KVM Forum block no[td]es

[Alberto Garcia <berto@igalia.com>]

(I just wanted to reply quickly to this point, I'll read the rest of the
e-mail later)

On Fri 16 Nov 2018 05:34:08 PM CET, Max Reitz <mreitz@redhat.com> wrote:
> > GRAPH_MOD with the meaning that Berto suggested isn't weird or
> > complicated to understand. It's only the wrong tool because it
> > blocks more than we want to block. But if we didn't care about that,
> > it could be just another permission like any other.

That's the way that I understood it. Or, more precisely, I'm basing my
current code on those assumptions because it's a simple starting point
to have something working with the current permission system. But I'm of
course open to trying a different approach.

> The meaning Berto has suggested (AFAIU) is never taking the permission
> at all but just querying whether it is shared by all current parents
> before doing a graph change.

That would be a quick way to test it, and I agree that it's unorthodox,
but it's useful to explain how I understood the meaning of GRAPH_MOD.

But you could for example make BDRVReopenState a parent of the BDS (and
replace BDRVReopenState.bs with a BdrvChild).

Berto