[ndctl PATCH] ndctl: recover from failed namespace creation

[oceanhehy@gmail.com]

From: Ocean He <hehy1@lenovo.com>

When namespace creation failure occurs, the consumed namespace (seed or 0th
idle) and pfn/dax seed would block next namespace creation. A recovery is
needed to handle this type failure.

A symptom example (section size is 128MB) based on kernel 4.19-rc2 and
ndctl v62:
	# ndctl create-namespace -r region1 -s 100m -t pmem -m fsdax
	{
	  "dev":"namespace1.0",
	  "mode":"fsdax",
	  "map":"dev",
	  "size":"96.00 MiB (100.66 MB)",
	  "uuid":"ef9a0556-a610-40b5-8c71-43991765a2cc",
	  "raw_uuid":"177b22e2-b7e8-482f-a063-2b8de876d979",
	  "sector_size":512,
	  "blockdev":"pmem1",
	  "numa_node":1
	}
	# ndctl create-namespace -r region1 -s 100m -t pmem -m fsdax
	libndctl: ndctl_pfn_enable: pfn1.1: failed to enable
	  Error: namespace1.1: failed to enable
	failed to create namespace: No such device or address
	# ndctl destroy-namespace namespace1.0 -f
	destroyed 1 namespace
	# ndctl create-namespace -r region1 -s 128m -t pmem -m fsdax
	failed to create namespace: Device or resource busy

Signed-off-by: Ocean He <hehy1@lenovo.com>
---
Additional information:
A kernel patch to fix this has been reviewed by Dan Williams, and he prefers
to handle it in ndctl directly.
https://www.spinics.net/lists/kernel/msg2901465.html

 ndctl/namespace.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/ndctl/namespace.c b/ndctl/namespace.c
index 510553c..76ee2ed 100644
--- a/ndctl/namespace.c
+++ b/ndctl/namespace.c
@@ -393,6 +393,8 @@ static int setup_namespace(struct ndctl_region *region,
 			try(ndctl_pfn, set_align, pfn, p->align);
 		try(ndctl_pfn, set_namespace, pfn, ndns);
 		rc = ndctl_pfn_enable(pfn);
+		if (rc)
+			ndctl_pfn_set_namespace(pfn, NULL);
 	} else if (p->mode == NDCTL_NS_MODE_DAX) {
 		struct ndctl_dax *dax = ndctl_region_get_dax_seed(region);
 
@@ -402,6 +404,8 @@ static int setup_namespace(struct ndctl_region *region,
 		try(ndctl_dax, set_align, dax, p->align);
 		try(ndctl_dax, set_namespace, dax, ndns);
 		rc = ndctl_dax_enable(dax);
+		if (rc)
+			ndctl_dax_set_namespace(dax, NULL);
 	} else if (p->mode == NDCTL_NS_MODE_SAFE) {
 		struct ndctl_btt *btt = ndctl_region_get_btt_seed(region);
 
@@ -783,7 +787,13 @@ static int namespace_create(struct ndctl_region *region)
 		return -ENODEV;
 	}
 
-	return setup_namespace(region, ndns, &p);
+	rc = setup_namespace(region, ndns, &p);
+	if (rc) {
+		ndctl_namespace_set_enforce_mode(ndns, NDCTL_NS_MODE_RAW);
+		ndctl_namespace_delete(ndns);
+	}
+
+	return rc;
 }
 
 static int zero_info_block(struct ndctl_namespace *ndns)
-- 
1.8.3.1

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