libnvdimm, namespace: update label implementation for multi-pmem

Instead of assuming that there will only ever be one allocated range at
the start of the region, account for additional namespaces that might
start at an offset from the region base.

After this change pmem namespaces now have a reason to carry an array of
resources similar to blk.  Unifying the resource tracking infrastructure
in nd_namespace_common is a future cleanup candidate.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/label.c

@@ -494,12 +494,13 @@ static int __pmem_label_update(struct nd_region *nd_region,
 		struct nd_mapping *nd_mapping, struct nd_namespace_pmem *nspm,
 		int pos)
 {
-	u64 cookie = nd_region_interleave_set_cookie(nd_region), rawsize;
+	u64 cookie = nd_region_interleave_set_cookie(nd_region);
 	struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
-	struct nd_namespace_label *victim_label;
+	struct nd_label_ent *label_ent, *victim = NULL;
 	struct nd_namespace_label *nd_label;
 	struct nd_namespace_index *nsindex;
-	struct nd_label_ent *label_ent;
+	struct nd_label_id label_id;
+	struct resource *res;
 	unsigned long *free;
 	u32 nslot, slot;
 	size_t offset;
@@ -508,6 +509,16 @@ static int __pmem_label_update(struct nd_region *nd_region,
 	if (!preamble_next(ndd, &nsindex, &free, &nslot))
 		return -ENXIO;
 
+	nd_label_gen_id(&label_id, nspm->uuid, 0);
+	for_each_dpa_resource(ndd, res)
+		if (strcmp(res->name, label_id.id) == 0)
+			break;
+
+	if (!res) {
+		WARN_ON_ONCE(1);
+		return -ENXIO;
+	}
+
 	/* allocate and write the label to the staging (next) index */
 	slot = nd_label_alloc_slot(ndd);
 	if (slot == UINT_MAX)
@@ -523,11 +534,10 @@ static int __pmem_label_update(struct nd_region *nd_region,
 	nd_label->nlabel = __cpu_to_le16(nd_region->ndr_mappings);
 	nd_label->position = __cpu_to_le16(pos);
 	nd_label->isetcookie = __cpu_to_le64(cookie);
-	rawsize = div_u64(resource_size(&nspm->nsio.res),
-			nd_region->ndr_mappings);
-	nd_label->rawsize = __cpu_to_le64(rawsize);
-	nd_label->dpa = __cpu_to_le64(nd_mapping->start);
+	nd_label->rawsize = __cpu_to_le64(resource_size(res));
+	nd_label->dpa = __cpu_to_le64(res->start);
 	nd_label->slot = __cpu_to_le32(slot);
+	nd_dbg_dpa(nd_region, ndd, res, "%s\n", __func__);
 
 	/* update label */
 	offset = nd_label_offset(ndd, nd_label);
@@ -538,22 +548,39 @@ static int __pmem_label_update(struct nd_region *nd_region,
 
 	/* Garbage collect the previous label */
 	mutex_lock(&nd_mapping->lock);
-	label_ent = list_first_entry_or_null(&nd_mapping->labels,
-			typeof(*label_ent), list);
-	WARN_ON(!label_ent);
-	victim_label = label_ent ? label_ent->label : NULL;
-	if (victim_label) {
-		label_ent->label = NULL;
-		slot = to_slot(ndd, victim_label);
-		nd_label_free_slot(ndd, slot);
+	list_for_each_entry(label_ent, &nd_mapping->labels, list) {
+		if (!label_ent->label)
+			continue;
+		if (memcmp(nspm->uuid, label_ent->label->uuid,
+					NSLABEL_UUID_LEN) != 0)
+			continue;
+		victim = label_ent;
+		list_move_tail(&victim->list, &nd_mapping->labels);
+		break;
+	}
+	if (victim) {
 		dev_dbg(ndd->dev, "%s: free: %d\n", __func__, slot);
+		slot = to_slot(ndd, victim->label);
+		nd_label_free_slot(ndd, slot);
+		victim->label = NULL;
 	}
 
 	/* update index */
 	rc = nd_label_write_index(ndd, ndd->ns_next,
 			nd_inc_seq(__le32_to_cpu(nsindex->seq)), 0);
-	if (rc == 0 && label_ent)
-		label_ent->label = nd_label;
+	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(&nspm->nsio.common.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;
@@ -899,7 +926,9 @@ int nd_pmem_namespace_label_update(struct nd_region *nd_region,
 
 	for (i = 0; i < nd_region->ndr_mappings; i++) {
 		struct nd_mapping *nd_mapping = &nd_region->mapping[i];
-		int rc;
+		struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
+		struct resource *res;
+		int rc, count = 0;
 
 		if (size == 0) {
 			rc = del_labels(nd_mapping, nspm->uuid);
@@ -908,7 +937,12 @@ int nd_pmem_namespace_label_update(struct nd_region *nd_region,
 			continue;
 		}
 
-		rc = init_labels(nd_mapping, 1);
+		for_each_dpa_resource(ndd, res)
+			if (strncmp(res->name, "pmem", 3) == 0)
+				count++;
+		WARN_ON_ONCE(!count);
+
+		rc = init_labels(nd_mapping, count);
 		if (rc < 0)
 			return rc;