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

[Hannes Reinecke]

On 5/10/21 8:23 AM, Christoph Hellwig wrote:
> On Fri, May 07, 2021 at 07:02:52PM +0200, Hannes Reinecke wrote:
>> On 5/7/21 8:46 AM, Christoph Hellwig wrote:
>>> On Thu, May 06, 2021 at 05:54:29PM +0200, Hannes Reinecke wrote:
>>>> 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).
> 
> Yes.  But that has nothing to do with fabrics as you claimed above, but
> with the fact if the subsystem supports multiple controller (and thus
> shared namespaces) or not.
> 
So, I seem to have reproduced the issue with latest nvme-5.13.
The failure pattern is slightly different, so I think I've been able to
solve is in a slightly less controversial manner.

Patch to follow.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		        Kernel Storage Architect
hare at suse.de			               +49 911 74053 688
SUSE Software Solutions Germany GmbH, 90409 Nürnberg
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