Re: [RFC PATCH 02/20] nvdimm/label: Prep patch to accommodate cxl lsa 2.1 support

[Neeraj Kumar <s.neeraj@samsung.com>]

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On 23/06/25 11:53AM, Jonathan Cameron wrote:
>On Tue, 17 Jun 2025 18:09:26 +0530
>Neeraj Kumar <s.neeraj@samsung.com> wrote:
>
>> In order to accommodate cxl lsa 2.1 format region label, renamed
>> nd_namespace_label to nd_lsa_label.
>
>I would add some more information on why.  I've no idea from this
>description whether the issue is a naming clash or a need for a broader
>name or something entirely different.
>
>Most readers aren't going to be particular familiar with the lsa spec
>version changes, so help them out with a little more detail.
>
>The comment you have with the union is probably the right info
>to duplicate here.
>

Thanks Jonathan, I will elaborate commit message with more information.

>>
>> No functional change introduced.
>>
>> Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
>
>This is quite a lot of churn which, just looking at this patch, could
>be avoided by just setting local variables to point at a particular
>member of the union rather than the containing struct.
>You already do this in a few places like nd_label_reserve_dpa().
>
>Perhaps it will be come clearer why that doesn't make sense as
>I ready later patches.
>

Sure, I will try to minimize wherever its possible.

>> diff --git a/drivers/nvdimm/label.h b/drivers/nvdimm/label.h
>> index 0650fb4b9821..4883b3a1320f 100644
>> --- a/drivers/nvdimm/label.h
>> +++ b/drivers/nvdimm/label.h
>> @@ -183,6 +183,16 @@ struct nd_namespace_label {
>>  	};
>>  };
>>
>> +/*
>> + * LSA 2.1 format introduces region label, which can also reside
>> + * into LSA along with only namespace label as per v1.1 and v1.2
>> + */
>> +struct nd_lsa_label {
>> +	union {
>> +		struct nd_namespace_label ns_label;
>> +	};
>> +};
>
>> diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
>> index 55cfbf1e0a95..f180f0068c15 100644
>> --- a/drivers/nvdimm/namespace_devs.c
>> +++ b/drivers/nvdimm/namespace_devs.c
>
>> @@ -1595,7 +1596,8 @@ static bool has_uuid_at_pos(struct nd_region *nd_region, const uuid_t *uuid,
>>  				return false;
>>  			}
>>  			found_uuid = true;
>> -			if (!nsl_validate_nlabel(nd_region, ndd, nd_label))
>> +			if (!nsl_validate_nlabel(nd_region,
>> +						 ndd, &nd_label->ns_label))
>
>Strange wrap.  I'd move ndd up a line.
>
>

Sure, I will fix it in V1

>>  				continue;
>>  			if (position != pos)
>>  				continue;
>> @@ -1615,7 +1617,7 @@ static int select_pmem_id(struct nd_region *nd_region, const uuid_t *pmem_id)
>>  	for (i = 0; i < nd_region->ndr_mappings; i++) {
>>  		struct nd_mapping *nd_mapping = &nd_region->mapping[i];
>>  		struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
>> -		struct nd_namespace_label *nd_label = NULL;
>> +		struct nd_lsa_label *nd_label = NULL;
>>  		u64 hw_start, hw_end, pmem_start, pmem_end;
>>  		struct nd_label_ent *label_ent;
>>
>
>
>> @@ -1739,14 +1741,14 @@ static struct device *create_namespace_pmem(struct nd_region *nd_region,
>>  	 * that position at labels[0], and NULL at labels[1].  In the process,
>>  	 * check that the namespace aligns with interleave-set.
>>  	 */
>> -	nsl_get_uuid(ndd, nd_label, &uuid);
>> +	nsl_get_uuid(ndd, &nd_label->ns_label, &uuid);
>>  	rc = select_pmem_id(nd_region, &uuid);
>>  	if (rc)
>>  		goto err;
>>
>>  	/* Calculate total size and populate namespace properties from label0 */
>>  	for (i = 0; i < nd_region->ndr_mappings; i++) {
>> -		struct nd_namespace_label *label0;
>> +		struct nd_lsa_label *label0;
>
>If you are only ever going to use one part of the union in a given
>bit of code, why not use a struct of that type so you only need to change
>the point where it is assigned rather that lots of places.
>
>So keep this as struct nd_namespace_label *label0;
>
>If that makes sense, check for other places where doing that will reduce the churn
>and complexity of the code.
>

Sure, Let me revisit these. Thanks

>
>
>>  		struct nvdimm_drvdata *ndd;
>>
>>  		nd_mapping = &nd_region->mapping[i];
>> @@ -1760,17 +1762,17 @@ static struct device *create_namespace_pmem(struct nd_region *nd_region,
>>  		}
>>
>>  		ndd = to_ndd(nd_mapping);
>> -		size += nsl_get_rawsize(ndd, label0);
>> -		if (nsl_get_position(ndd, label0) != 0)
>> +		size += nsl_get_rawsize(ndd, &label0->ns_label);
>> +		if (nsl_get_position(ndd, &label0->ns_label) != 0)
>>  			continue;
>>  		WARN_ON(nspm->alt_name || nspm->uuid);
>> -		nspm->alt_name = kmemdup(nsl_ref_name(ndd, label0),
>> +		nspm->alt_name = kmemdup(nsl_ref_name(ndd, &label0->ns_label),
>>  					 NSLABEL_NAME_LEN, GFP_KERNEL);
>> -		nsl_get_uuid(ndd, label0, &uuid);
>> +		nsl_get_uuid(ndd, &label0->ns_label, &uuid);
>>  		nspm->uuid = kmemdup(&uuid, sizeof(uuid_t), GFP_KERNEL);
>> -		nspm->lbasize = nsl_get_lbasize(ndd, label0);
>> +		nspm->lbasize = nsl_get_lbasize(ndd, &label0->ns_label);
>>  		nspm->nsio.common.claim_class =
>> -			nsl_get_claim_class(ndd, label0);
>> +			nsl_get_claim_class(ndd, &label0->ns_label);
>>  	}
>

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