moutnroot failing on zpools in Azure after upgrade from 10 to 11 due to lack of waiting for da0

[Pete French]

> So, the kernel attempted to mount the root even before vmbus was attached and,
> thus, before storvsc appeared and informed the kernel that it might be holding
> the root.
> How ZFS was supposed to know that vmbus is ever going to appear?
> To me this sounds more like a problem with the Hyper-V drivers.

I am currently running with the patch which waits for a number fo 
seconds and retries the mount, and that appears t fix it. However I dont 
really like rnning a patched OS. How would I set about reporting this to 
Microsoft and getting it fixed, or getting the timeoutpatch commited ? 
Preferably both, as the timeout patch is generally a useful thing to 
have working for ZFS I think.

-pete.