Re: [RFC PATCH 05/20] nvdimm/region_label: Add region label updation routine

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

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On 18/07/25 12:53AM, Fabio M. De Francesco wrote:
>On Tuesday, June 17, 2025 2:39:29 PM Central European Summer Time Neeraj Kumar wrote:
>> Added __pmem_region_label_update region label update routine to update
>> region label
>>
>> Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
>> ---
>>  drivers/nvdimm/label.c          | 142 ++++++++++++++++++++++++++++++++
>>  drivers/nvdimm/label.h          |   2 +
>>  drivers/nvdimm/namespace_devs.c |  12 +++
>>  drivers/nvdimm/nd.h             |  20 +++++
>>  include/linux/libnvdimm.h       |   8 ++
>>  5 files changed, 184 insertions(+)
>>
>> diff --git a/drivers/nvdimm/label.c b/drivers/nvdimm/label.c
>> index d5cfaa99f976..7f33d14ce0ef 100644
>> --- a/drivers/nvdimm/label.c
>> +++ b/drivers/nvdimm/label.c
>> @@ -381,6 +381,16 @@ static void nsl_calculate_checksum(struct nvdimm_drvdata *ndd,
>>  	nsl_set_checksum(ndd, nd_label, sum);
>>  }
>>
>> +static void rgl_calculate_checksum(struct nvdimm_drvdata *ndd,
>> +				   struct cxl_region_label *rg_label)
>> +{
>> +	u64 sum;
>> +
>> +	rgl_set_checksum(rg_label, 0);
>> +	sum = nd_fletcher64(rg_label, sizeof_namespace_label(ndd), 1);
>> +	rgl_set_checksum(rg_label, sum);
>> +}
>> +
>>  static bool slot_valid(struct nvdimm_drvdata *ndd,
>>  		struct nd_lsa_label *nd_label, u32 slot)
>>  {
>> @@ -1117,6 +1127,138 @@ int nd_pmem_namespace_label_update(struct nd_region *nd_region,
>>  	return 0;
>>  }
>>
>> +static int __pmem_region_label_update(struct nd_region *nd_region,
>> +		struct nd_mapping *nd_mapping, int pos, unsigned long flags)
>
>Hi Neeraj,
>
>I've noticed that __pmem_region_label_update() shares many similarities
>with the existing __pmem_label_update().

Hi Fabio,

Yes these functions looks similar, as one is updating namespace label
and other (__pmem_region_label_update) is updating region label. But
they don't use much duplicated code.

May be I will try refactoring to avoid any duplicate code.

>
>> +{
>> +	struct nd_interleave_set *nd_set = nd_region->nd_set;
>> +	struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
>> +	struct nd_lsa_label *nd_label;
>> +	struct cxl_region_label *rg_label;
>> +	struct nd_namespace_index *nsindex;
>> +	struct nd_label_ent *label_ent;
>> +	unsigned long *free;
>> +	u32 nslot, slot;
>> +	size_t offset;
>> +	int rc;
>> +	uuid_t tmp;
>> +
>> +	if (!preamble_next(ndd, &nsindex, &free, &nslot))
>> +		return -ENXIO;
>> +
>> +	/* allocate and write the label to the staging (next) index */
>> +	slot = nd_label_alloc_slot(ndd);
>> +	if (slot == UINT_MAX)
>> +		return -ENXIO;
>> +	dev_dbg(ndd->dev, "allocated: %d\n", slot);
>> +
>> +	nd_label = to_label(ndd, slot);
>> +
>> +	memset(nd_label, 0, sizeof_namespace_label(ndd));
>> +	rg_label = &nd_label->rg_label;
>> +
>> +	/* Set Region Label Format identification UUID */
>> +	uuid_parse(CXL_REGION_UUID, &tmp);
>> +	export_uuid(nd_label->rg_label.type, &tmp);
>> +
>> +	/* Set Current Region Label UUID */
>> +	export_uuid(nd_label->rg_label.uuid, &nd_set->uuid);
>> +
>> +	rg_label->flags = __cpu_to_le32(flags);
>> +	rg_label->nlabel = __cpu_to_le16(nd_region->ndr_mappings);
>> +	rg_label->position = __cpu_to_le16(pos);
>> +	rg_label->dpa = __cpu_to_le64(nd_mapping->start);
>> +	rg_label->rawsize = __cpu_to_le64(nd_mapping->size);
>> +	rg_label->hpa = __cpu_to_le64(nd_set->res->start);
>> +	rg_label->slot = __cpu_to_le32(slot);
>> +	rg_label->ig = __cpu_to_le32(nd_set->interleave_granularity);
>> +	rg_label->align = __cpu_to_le16(0);
>> +
>> +	/* Update fletcher64 Checksum */
>> +	rgl_calculate_checksum(ndd, rg_label);
>> +
>> +	/* update label */
>> +	offset = nd_label_offset(ndd, nd_label);
>> +	rc = nvdimm_set_config_data(ndd, offset, nd_label,
>> +			sizeof_namespace_label(ndd));
>> +	if (rc < 0) {
>> +		nd_label_free_slot(ndd, slot);
>> +		return rc;
>> +	}
>> +
>> +	/* Garbage collect the previous label */
>> +	mutex_lock(&nd_mapping->lock);
>> +	list_for_each_entry(label_ent, &nd_mapping->labels, list) {
>> +		if (!label_ent->label)
>> +			continue;
>> +		if (rgl_uuid_equal(&label_ent->label->rg_label, &nd_set->uuid))
>> +			reap_victim(nd_mapping, label_ent);
>> +	}
>> +
>> +	/* update index */
>> +	rc = nd_label_write_index(ndd, ndd->ns_next,
>> +			nd_inc_seq(__le32_to_cpu(nsindex->seq)), 0);
>> +
>> +	if (rc == 0) {
>> +		list_for_each_entry(label_ent, &nd_mapping->labels, list)
>> +			if (!label_ent->label) {
>> +				label_ent->label = nd_label;
>> +				nd_label = NULL;
>> +				break;
>> +			}
>> +		dev_WARN_ONCE(&nd_region->dev, nd_label,
>> +				"failed to track label: %d\n",
>> +				to_slot(ndd, nd_label));
>> +		if (nd_label)
>> +			rc = -ENXIO;
>> +	}
>> +	mutex_unlock(&nd_mapping->lock);
>> +
>> +	return rc;
>> +}
>> +
>> +int nd_pmem_region_label_update(struct nd_region *nd_region)
>
>Same here. nd_pmem_region_label_update() is almost identical to the
>existing nd_pmem_namespace_label_update.

Sure, I will try refactoring these in next patch-set.

>
>Although I'm not familiar with drivers/nvdimm, it seems preferable to
>reuse and adapt the existing functions to reduce redundancy and simplify
>future maintenance, unless there are specific reasons for not doing so
>that I'm unaware of.
>
>Thanks,
>
>Fabio

Thanks Fabio for your feedback.

Regards,
Neeraj

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