[PATCH v2] nvdimm/pmem: propagate personality discovery errors

[Avi Weiss <thnkslprpt@gmail.com>]

nd_pmem_probe() ignores errors from BTT discovery and only propagates
-EOPNOTSUPP from PFN and DAX discovery. Allocation failures can therefore
be mistaken for an absent personality, allowing a namespace to fall back
to raw PMEM.

Report -ENOMEM when allocating the BTT, PFN, or DAX info-block buffer
fails, retaining the existing device cleanup paths. Propagate discovery
errors other than -ENODEV and -ENXIO, and keep raw-PMEM fallback for
those two error codes.

Fixes: 8c2f7e8658df ("libnvdimm: infrastructure for btt devices")
Signed-off-by: Avi Weiss <thnkslprpt@gmail.com>
---

v2:
- return -ENOMEM for BTT, PFN, and DAX superblock buffer
  allocation failures, retaining the existing cleanup paths
- correct/clarify the comment describing raw-PMEM fallback and
  namespace-seed advancement
- rebase to v7.4-rc1

 drivers/nvdimm/btt_devs.c |  4 +++-
 drivers/nvdimm/dax_devs.c |  4 +++-
 drivers/nvdimm/pfn_devs.c |  4 +++-
 drivers/nvdimm/pmem.c     | 19 ++++++++-----------
 4 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
index d6b2f157368f6..c3c5cb686743b 100644
--- a/drivers/nvdimm/btt_devs.c
+++ b/drivers/nvdimm/btt_devs.c
@@ -349,7 +349,9 @@ int nd_btt_probe(struct device *dev, struct nd_namespace_common *ndns)
 	if (!btt_dev)
 		return -ENOMEM;
 	btt_sb = devm_kzalloc(dev, sizeof(*btt_sb), GFP_KERNEL);
-	rc = __nd_btt_probe(to_nd_btt(btt_dev), ndns, btt_sb);
+	rc = -ENOMEM;
+	if (btt_sb)
+		rc = __nd_btt_probe(to_nd_btt(btt_dev), ndns, btt_sb);
 	dev_dbg(dev, "btt: %s\n", rc == 0 ? dev_name(btt_dev) : "<none>");
 	if (rc < 0) {
 		struct nd_btt *nd_btt = to_nd_btt(btt_dev);
diff --git a/drivers/nvdimm/dax_devs.c b/drivers/nvdimm/dax_devs.c
index decc70f2fe3ff..4d4048578efac 100644
--- a/drivers/nvdimm/dax_devs.c
+++ b/drivers/nvdimm/dax_devs.c
@@ -113,7 +113,9 @@ int nd_dax_probe(struct device *dev, struct nd_namespace_common *ndns)
 	pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
 	nd_pfn = &nd_dax->nd_pfn;
 	nd_pfn->pfn_sb = pfn_sb;
-	rc = nd_pfn_validate(nd_pfn, DAX_SIG);
+	rc = -ENOMEM;
+	if (pfn_sb)
+		rc = nd_pfn_validate(nd_pfn, DAX_SIG);
 	dev_dbg(dev, "dax: %s\n", rc == 0 ? dev_name(dax_dev) : "<none>");
 	if (rc < 0) {
 		nd_detach_ndns(dax_dev, &nd_pfn->ndns);
diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 8fa9c16aba7ea..39b8d5eed7ef5 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -637,7 +637,9 @@ int nd_pfn_probe(struct device *dev, struct nd_namespace_common *ndns)
 	pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
 	nd_pfn = to_nd_pfn(pfn_dev);
 	nd_pfn->pfn_sb = pfn_sb;
-	rc = nd_pfn_validate(nd_pfn, PFN_SIG);
+	rc = -ENOMEM;
+	if (pfn_sb)
+		rc = nd_pfn_validate(nd_pfn, PFN_SIG);
 	dev_dbg(dev, "pfn: %s\n", rc == 0 ? dev_name(pfn_dev) : "<none>");
 	if (rc < 0) {
 		nd_detach_ndns(pfn_dev, &nd_pfn->ndns);
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 0766a6949b285..efdb804ad5d78 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -632,28 +632,25 @@ static int nd_pmem_probe(struct device *dev)
 	ret = nd_btt_probe(dev, ndns);
 	if (ret == 0)
 		return -ENXIO;
+	else if (ret != -ENODEV && ret != -ENXIO)
+		return ret;
 
 	/*
-	 * 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.
+	 * An absent or unreadable PFN/DAX info block allows probing the
+	 * next personality or falling back to raw PMEM. Other errors
+	 * are propagated, including -EOPNOTSUPP, which causes
+	 * nvdimm_bus_probe() to advance the namespace seed.
 	 */
 	ret = nd_pfn_probe(dev, ndns);
 	if (ret == 0)
 		return -ENXIO;
-	else if (ret == -EOPNOTSUPP)
+	else if (ret != -ENODEV && ret != -ENXIO)
 		return ret;
 
 	ret = nd_dax_probe(dev, ndns);
 	if (ret == 0)
 		return -ENXIO;
-	else if (ret == -EOPNOTSUPP)
+	else if (ret != -ENODEV && ret != -ENXIO)
 		return ret;
 
 	/* probe complete, attach handles namespace enabling */

base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
-- 
2.43.0