[PATCH v6 2/7] libnvdimm/pmem: Advance namespace seed for specific probe errors

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

In order to support marking namespaces with unsupported feature/versions
disabled, nvdimm core should advance the namespace seed on these
probe failures. Otherwise, these failed namespaces will be considered a
seed namespace and will be wrongly used while creating new namespaces.

Add -EOPNOTSUPP as return from pmem probe callback to indicate a namespace
initialization failures due to pfn superblock feature/version mismatch.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 drivers/nvdimm/bus.c  |  3 ++-
 drivers/nvdimm/pmem.c | 29 +++++++++++++++++++++++++----
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 9b64e68a20b8..69f784bf9744 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -95,7 +95,8 @@ static int nvdimm_bus_probe(struct device *dev)
 	rc = nd_drv->probe(dev);
 	debug_nvdimm_unlock(dev);
 
-	if (rc == 0 && dev->parent && is_nd_region(dev->parent))
+	if ((rc == 0 || rc == -EOPNOTSUPP) &&
+	    dev->parent && is_nd_region(dev->parent))
 		nd_region_advance_seeds(to_nd_region(dev->parent), dev);
 	nvdimm_bus_probe_end(nvdimm_bus);
 
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 4c121dd03dd9..f9f76f6ba07b 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -490,6 +490,7 @@ static int pmem_attach_disk(struct device *dev,
 
 static int nd_pmem_probe(struct device *dev)
 {
+	int ret;
 	struct nd_namespace_common *ndns;
 
 	ndns = nvdimm_namespace_common_probe(dev);
@@ -505,12 +506,32 @@ static int nd_pmem_probe(struct device *dev)
 	if (is_nd_pfn(dev))
 		return pmem_attach_disk(dev, ndns);
 
-	/* if we find a valid info-block we'll come back as that personality */
-	if (nd_btt_probe(dev, ndns) == 0 || nd_pfn_probe(dev, ndns) == 0
-			|| nd_dax_probe(dev, ndns) == 0)
+	ret = nd_btt_probe(dev, ndns);
+	if (ret == 0)
 		return -ENXIO;
 
-	/* ...otherwise we're just a raw pmem device */
+	/*
+	 * We have two failure conditions here, there is no
+	 * info reserver block or we found a valid info reserve block
+	 * but failed to initialize the pfn superblock.
+	 *
+	 * For the first case consider namespace as a raw pmem namespace
+	 * and attach a disk.
+	 *
+	 * For the latter, consider this a success and advance the namespace
+	 * seed.
+	 */
+	ret = nd_pfn_probe(dev, ndns);
+	if (ret == 0)
+		return -ENXIO;
+	else if (ret == -EOPNOTSUPP)
+		return ret;
+
+	ret = nd_dax_probe(dev, ndns);
+	if (ret == 0)
+		return -ENXIO;
+	else if (ret == -EOPNOTSUPP)
+		return ret;
 	return pmem_attach_disk(dev, ndns);
 }
 
-- 
2.21.0

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