Re: [PATCH 00/13] scsi: Core ALUA driver

[Hannes Reinecke <hare@suse.com>]

On 3/24/26 16:12, John Garry wrote:
> On 24/03/2026 13:58, Benjamin Marzinski wrote:
>>>> If it allowed device handlers to get attached, these two
>>>> developement efforts (native scsi multipath and refactoring the alua
>>>> support) could go on in parallel.
>>>>
>>>> Or am I missing something here?
>>> It just seems to be about this DH stuff is that there is bad history 
>>> there
>>> and no more users are wanted.
>> Just to be clear, if the idea was that the Native Multipath code
>> shouldn't use include/scsi/scsi_dh.h, I completely agree with that. But
>> I don't see why it can't make use of the results of the existing
>> implicit ALUA support, since IIUC it doesn't need the scsi_dh interface
>> to do that.
> 
> We would need something like the following to ensure that DH ALUA is 
> present to update sdev access_state:
> 
> @@ -80,6 +80,7 @@ config SCSI_MULTIPATH
>          bool "SCSI multipath support"
>          depends on SCSI_MOD
>          select LIBMULTIPATH
> +       select SCSI_DH_ALUA
>          help
>            This option enables support for native SCSI multipath support 
> for
>            SCSI host.
> 
> And that is even enough, as Kconfigs should only specify build 
> requirements.
> 
> We really should be also calling something like scsi_dh_attach() for 
> scsi multipath to ensure that DH is attached (and running to update 
> sdev->access_state).
> 
> And I am not sure how the dh alua module is even autoloaded. I think 
> that on my ubuntu machine the multipath-tools.service does it - 
> something like this would not be nice for native SCSI multipath support.
> 
Gnaa. But then we don't need this patchset at all.
Main point was that we _do not_ need to hook into scsi dh for implicit
ALUA.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.com                               +49 911 74053 688
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