[PATCH RFC] nvme-multipath: don't retry adding head disk

[John Garry]

On 30/07/2026 12:40, Christoph Hellwig wrote:
> On Wed, Jul 29, 2026 at 06:22:35PM +0000, John Garry wrote:
>> From: John Garry <john.garry at linux.dev>
>> 
>> If an attempt to add the head disk in nvme_mpath_set_live() ->
>> device_add_disk() fails, then flag NVME_NSHEAD_DISK_LIVE is cleared and
>> we bail out.
>> 
>> However, we may later call nvme_mpath_set_live() -> device_add_disk() again
>> for another NS or from ANA updates for the same NS. This is broken, as we
>> should not retry adding the disk - it breaks the driver model.
>> 
>> Add a flag NVME_NSHEAD_DISK_BROKEN to stop this happening.
>> 
>> Signed-off-by: John Garry <john.g.garry at oracle.com>
>> ---
>> I'm not happy with this solution, as we have a DOA disk and it would be
>> better to remove the NSes in this case. OTOH, this device_add_disk()
>> failure is very unlikely to happen, so we should not add a complex
>> solution to handle it.
> 
> Yeah.  Broken is a bit weird of a name for something that would
> either be a logic bug or a really messed up kernel, though.

NVME_NSHEAD_DISK_FAILED or NVME_NSHEAD_DISK_FAILED_ADD

> 
> I guess you arrive there by error injection?

I just bodged an error in device_add_disk(). btw, sashiko notified me 
about this issue elsewhere.