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

["Fabio M. De Francesco" <fabio.m.de.francesco@linux.intel.com>]

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().

> +{
> +	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. 

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

> +{
> +	int i, rc;
> +
> +	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);
> +
> +		/* No need to update region label for non cxl format */
> +		if (!ndd->cxl)
> +			continue;
> +
> +		/* Init labels to include region label */
> +		rc = init_labels(nd_mapping, 1);
> +
> +		if (rc < 0)
> +			return rc;
> +
> +		rc = __pmem_region_label_update(nd_region, nd_mapping, i,
> +					NSLABEL_FLAG_UPDATING);
> +
> +		if (rc)
> +			return rc;
> +	}
> +
> +	/* Clear the UPDATING flag per UEFI 2.7 expectations */
> +	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);
> +
> +		/* No need to update region label for non cxl format */
> +		if (!ndd->cxl)
> +			continue;
> +
> +		rc = __pmem_region_label_update(nd_region, nd_mapping, i, 0);
> +
> +		if (rc)
> +			return rc;
> +	}
> +
> +	return 0;
> +}
> +
>  int __init nd_label_init(void)
>  {
>  	WARN_ON(guid_parse(NVDIMM_BTT_GUID, &nvdimm_btt_guid));
> diff --git a/drivers/nvdimm/label.h b/drivers/nvdimm/label.h
> index 4883b3a1320f..0f428695017d 100644
> --- a/drivers/nvdimm/label.h
> +++ b/drivers/nvdimm/label.h
> @@ -190,6 +190,7 @@ struct nd_namespace_label {
>  struct nd_lsa_label {
>  	union {
>  		struct nd_namespace_label ns_label;
> +		struct cxl_region_label rg_label;
>  	};
>  };
>  
> @@ -233,4 +234,5 @@ struct nd_region;
>  struct nd_namespace_pmem;
>  int nd_pmem_namespace_label_update(struct nd_region *nd_region,
>  		struct nd_namespace_pmem *nspm, resource_size_t size);
> +int nd_pmem_region_label_update(struct nd_region *nd_region);
>  #endif /* __LABEL_H__ */
> diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
> index 23b9def71012..6cccb4d2fc7b 100644
> --- a/drivers/nvdimm/namespace_devs.c
> +++ b/drivers/nvdimm/namespace_devs.c
> @@ -232,6 +232,18 @@ static ssize_t __alt_name_store(struct device *dev, const char *buf,
>  	return rc;
>  }
>  
> +int nd_region_label_update(struct nd_region *nd_region)
> +{
> +	int rc;
> +
> +	nvdimm_bus_lock(&nd_region->dev);
> +	rc = nd_pmem_region_label_update(nd_region);
> +	nvdimm_bus_unlock(&nd_region->dev);
> +
> +	return rc;
> +}
> +EXPORT_SYMBOL_GPL(nd_region_label_update);
> +
>  static int nd_namespace_label_update(struct nd_region *nd_region,
>  		struct device *dev)
>  {
> diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
> index 07d665f18bf6..2fdc92b29e8a 100644
> --- a/drivers/nvdimm/nd.h
> +++ b/drivers/nvdimm/nd.h
> @@ -322,6 +322,26 @@ static inline void nsl_set_region_uuid(struct nvdimm_drvdata *ndd,
>  		export_uuid(ns_label->cxl.region_uuid, uuid);
>  }
>  
> +static inline bool rgl_uuid_equal(struct cxl_region_label *rg_label,
> +				  const uuid_t *uuid)
> +{
> +	uuid_t tmp;
> +
> +	import_uuid(&tmp, rg_label->uuid);
> +	return uuid_equal(&tmp, uuid);
> +}
> +
> +static inline u64 rgl_get_checksum(struct cxl_region_label *rg_label)
> +{
> +	return __le64_to_cpu(rg_label->checksum);
> +}
> +
> +static inline void rgl_set_checksum(struct cxl_region_label *rg_label,
> +				    u64 checksum)
> +{
> +	rg_label->checksum = __cpu_to_le64(checksum);
> +}
> +
>  bool nsl_validate_type_guid(struct nvdimm_drvdata *ndd,
>  			    struct nd_namespace_label *nd_label, guid_t *guid);
>  enum nvdimm_claim_class nsl_get_claim_class(struct nvdimm_drvdata *ndd,
> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
> index 0a55900842c8..b06bd45373f4 100644
> --- a/include/linux/libnvdimm.h
> +++ b/include/linux/libnvdimm.h
> @@ -115,6 +115,13 @@ struct nd_interleave_set {
>  	u64 altcookie;
>  
>  	guid_t type_guid;
> +
> +	/* v2.1 region label info */
> +	uuid_t uuid;
> +	int interleave_ways;
> +	int interleave_granularity;
> +	struct resource *res;
> +	int nr_targets;
>  };
>  
>  struct nd_mapping_desc {
> @@ -302,6 +309,7 @@ int nvdimm_has_flush(struct nd_region *nd_region);
>  int nvdimm_has_cache(struct nd_region *nd_region);
>  int nvdimm_in_overwrite(struct nvdimm *nvdimm);
>  bool is_nvdimm_sync(struct nd_region *nd_region);
> +int nd_region_label_update(struct nd_region *nd_region);
>  
>  static inline int nvdimm_ctl(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
>  		unsigned int buf_len, int *cmd_rc)
> -- 
> 2.34.1
> 
> 
> 
>