[PATCHv3] nvme-mpath: delete disk after last connection

[Sagi Grimberg]

>>> PCI and fabrics have different defaults; for PCI the device goes away if
>>> the last path (ie the controller) goes away, for fabrics it doesn't 
>>> if the
>>> device is mounted.
>>
>> Err, no.  For fabrics we reconnect a while, but otherwise the behavior
>> is the same right now.
>>
> No, that is not the case.
> 
> When a PCI nvme device with CMIC=0 is removed (via pci hotplug, say), 
> the nvme device is completely removed, irrespective on whether it's 
> mounted or not.
> When the _same_ PCI device with CMIC=1 is removed, the nvme device (ie 
> the nsnhead) will _stay_ when mounted (as the refcount is not zero).
> 
> This can be easily demonstrated on qemu; just set the 'subsys' parameter 
> for the nvme device.

Perhaps we need to fix the issue and allow the existing behavior by
having an explicit queue_if_no_path argument.