[ndctl PATCH 8/8] ndctl, create-namespace: check for ZONE_DEVICE=n kernels

[Dan Williams <dan.j.williams@intel.com>]

When a kernel does not support ZONE_DEVICE it is unable to support
pfn-device configurations.  Use the absence of a pfn-seed as the
indicator of this configuration to fail the operation with an error
rather than crashing.

Reported-by: Linda Knippers <linda.knippers@hpe.com>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 builtin-xaction-namespace.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/builtin-xaction-namespace.c b/builtin-xaction-namespace.c
index 6ae8d7aee849..6ff969cd696e 100644
--- a/builtin-xaction-namespace.c
+++ b/builtin-xaction-namespace.c
@@ -38,6 +38,7 @@ static bool verbose;
 static bool force;
 static struct parameters {
 	bool do_scan;
+	bool mode_default;
 	const char *bus;
 	const char *map;
 	const char *type;
@@ -153,6 +154,7 @@ static int set_defaults(enum namespace_action mode)
 			param.mode = "memory";
 		else
 			param.mode = "safe";
+		param.mode_default = true;
 	}
 
 	if (param.map) {
@@ -428,6 +430,22 @@ static int validate_namespace_options(struct ndctl_namespace *ndns,
 	} else if (p->mode == NDCTL_NS_MODE_MEMORY)
 		p->loc = NDCTL_PFN_LOC_PMEM;
 
+	/* check if we need, and whether the kernel supports, pfn devices */
+	if (do_setup_pfn(ndns, p)) {
+		struct ndctl_region *region;
+		struct ndctl_pfn *pfn;
+
+		region = ndctl_namespace_get_region(ndns);
+		pfn = ndctl_region_get_pfn_seed(region);
+		if (!pfn && param.mode_default) {
+			debug("memory mode not available\n");
+			p->mode = NDCTL_NS_MODE_RAW;
+		} else if (!pfn) {
+			error("operation failed, memory mode not available\n");
+			return -EINVAL;
+		}
+	}
+
 	return 0;
 }
 

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