linux-kernel - Re: [PATCH V2 02/20] nvdimm/label: Prep patch to accommodate cxl lsa 2.1 support

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Message-ID: <20250813142349.000032a4@huawei.com>
Date: Wed, 13 Aug 2025 14:23:49 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Neeraj Kumar <s.neeraj@...sung.com>
CC: <linux-cxl@...r.kernel.org>, <nvdimm@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>, <gost.dev@...sung.com>,
	<a.manzanares@...sung.com>, <vishak.g@...sung.com>, <neeraj.kernel@...il.com>
Subject: Re: [PATCH V2 02/20] nvdimm/label: Prep patch to accommodate cxl
 lsa 2.1 support

On Wed, 30 Jul 2025 17:41:51 +0530
Neeraj Kumar <s.neeraj@...sung.com> wrote:

> 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
> 
> As both namespace and region labels are of same size of 256 bytes.
> Thus renamed "struct nd_namespace_label" to "struct nd_lsa_label",
> where both namespace label and region label can stay as union.

Maybe add something on why it makes sense to use a union rather than
new handling.

> 
> No functional change introduced.
> 
> Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>
> ---
A few minor comments inline.


> diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
> index 55cfbf1e0a95..bdf1ed6f23d8 100644
> --- a/drivers/nvdimm/namespace_devs.c
> +++ b/drivers/nvdimm/namespace_devs.c
> @@ -1615,17 +1619,21 @@ 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_lsa_label *lsa_label = NULL;
Why not pull this into the scope below.

>  		struct nd_namespace_label *nd_label = NULL;
>  		u64 hw_start, hw_end, pmem_start, pmem_end;
>  		struct nd_label_ent *label_ent;
>  
>  		lockdep_assert_held(&nd_mapping->lock);
>  		list_for_each_entry(label_ent, &nd_mapping->labels, list) {
e.g.
			struct nd_lsa_label *lsa_label = label_ent->label;

then no need to set it to NULL later.

> -			nd_label = label_ent->label;
> -			if (!nd_label)
> +			lsa_label = label_ent->label;
> +			if (!lsa_label)
>  				continue;
> +
> +			nd_label = &lsa_label->ns_label;
>  			if (nsl_uuid_equal(ndd, nd_label, pmem_id))
>  				break;
> +			lsa_label = NULL;
>  			nd_label = NULL;
>  		}
>  
> @@ -1746,19 +1754,21 @@ static struct device *create_namespace_pmem(struct nd_region *nd_region,
>  
>  	/* Calculate total size and populate namespace properties from label0 */
>  	for (i = 0; i < nd_region->ndr_mappings; i++) {
> +		struct nd_lsa_label *lsa_label;
>  		struct nd_namespace_label *label0;
>  		struct nvdimm_drvdata *ndd;
>  
>  		nd_mapping = &nd_region->mapping[i];
>  		label_ent = list_first_entry_or_null(&nd_mapping->labels,
>  				typeof(*label_ent), list);
> -		label0 = label_ent ? label_ent->label : NULL;
> +		lsa_label = label_ent ? label_ent->label : NULL;
>  
> -		if (!label0) {
> +		if (!lsa_label) {
>  			WARN_ON(1);
>  			continue;
>  		}
>  
> +		label0 = &lsa_label->ns_label;
>  		ndd = to_ndd(nd_mapping);
>  		size += nsl_get_rawsize(ndd, label0);
>  		if (nsl_get_position(ndd, label0) != 0)
>