libnvdimm/labels: Introduce the concept of multi-range namespace labels

The CXL specification defines a mechanism for namespaces to be comprised
of multiple dis-contiguous ranges. Introduce that concept to the legacy
NVDIMM namespace implementation with a new nsl_set_nrange() helper, that
sets the number of ranges to 1. Once the NVDIMM subsystem supports CXL
labels and updates its namespace capacity provisioning for
dis-contiguous support nsl_set_nrange() can be updated, but in the
meantime CXL label validation requires nrange be non-zero.
Reported-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/163116430804.2460985.5482188351381597529.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/label.c

@@ -856,6 +856,7 @@ static int __pmem_label_update(struct nd_region *nd_region,
 	nsl_set_name(ndd, nd_label, nspm->alt_name);
 	nsl_set_flags(ndd, nd_label, flags);
 	nsl_set_nlabel(ndd, nd_label, nd_region->ndr_mappings);
+	nsl_set_nrange(ndd, nd_label, 1);
 	nsl_set_position(ndd, nd_label, pos);
 	nsl_set_isetcookie(ndd, nd_label, cookie);
 	nsl_set_rawsize(ndd, nd_label, resource_size(res));

drivers/nvdimm/nd.h

@@ -164,6 +164,19 @@ static inline void nsl_set_nlabel(struct nvdimm_drvdata *ndd,
 	nd_label->nlabel = __cpu_to_le16(nlabel);
 }
 
+static inline u16 nsl_get_nrange(struct nvdimm_drvdata *ndd,
+				 struct nd_namespace_label *nd_label)
+{
+	/* EFI labels do not have an nrange field */
+	return 1;
+}
+
+static inline void nsl_set_nrange(struct nvdimm_drvdata *ndd,
+				  struct nd_namespace_label *nd_label,
+				  u16 nrange)
+{
+}
+
 static inline u64 nsl_get_lbasize(struct nvdimm_drvdata *ndd,
 				  struct nd_namespace_label *nd_label)
 {