[PATCH] libnvdimm, namespace: do not delete namespace-id 0

From: Dan Williams
Date: Wed Feb 01 2017 - 13:39:31 EST


Given that the naming of pmem devices changes from the pmemX form to the
pmemX.Y form when namespace id is greater than 0, arrange for namespaces
with id-0 to be exempt from deletion. Otherwise a simple reconfiguration
of an existing namespace to a new mode results in a name change of the
resulting block device:

# ndctl list --namespace=namespace1.0
{
"dev":"namespace1.0",
"mode":"raw",
"size":2147483648,
"uuid":"3dadf3dc-89b9-4b24-b20e-abc8a4707ce3",
"blockdev":"pmem1"
}

# ndctl create-namespace --reconfig=namespace1.0 --mode=memory --force
{
"dev":"namespace1.1",
"mode":"memory",
"size":2111832064,
"uuid":"7b4a6341-7318-4219-a02c-fb57c0bbf613",
"blockdev":"pmem1.1"
}

This change does require tooling changes to explicitly look for
namespaceX.0 if the seed has already advanced to another namespace.

Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: 98a29c39dc68 ("libnvdimm, namespace: allow creation of multiple pmem-namespaces per region")
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/nvdimm/namespace_devs.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index eda027db0918..ce3e8dfa10ad 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -962,8 +962,8 @@ static ssize_t __size_store(struct device *dev, unsigned long long val)
struct nvdimm_drvdata *ndd;
struct nd_label_id label_id;
u32 flags = 0, remainder;
+ int rc, i, id = -1;
u8 *uuid = NULL;
- int rc, i;

if (dev->driver || ndns->claim)
return -EBUSY;
@@ -972,11 +972,13 @@ static ssize_t __size_store(struct device *dev, unsigned long long val)
struct nd_namespace_pmem *nspm = to_nd_namespace_pmem(dev);

uuid = nspm->uuid;
+ id = nspm->id;
} else if (is_namespace_blk(dev)) {
struct nd_namespace_blk *nsblk = to_nd_namespace_blk(dev);

uuid = nsblk->uuid;
flags = NSLABEL_FLAG_LOCAL;
+ id = nsblk->id;
}

/*
@@ -1039,10 +1041,11 @@ static ssize_t __size_store(struct device *dev, unsigned long long val)

/*
* Try to delete the namespace if we deleted all of its
- * allocation, this is not the seed device for the region, and
- * it is not actively claimed by a btt instance.
+ * allocation, this is not the seed or 0th device for the
+ * region, and it is not actively claimed by a btt, pfn, or dax
+ * instance.
*/
- if (val == 0 && nd_region->ns_seed != dev && !ndns->claim)
+ if (val == 0 && id != 0 && nd_region->ns_seed != dev && !ndns->claim)
nd_device_unregister(dev, ND_ASYNC);

return rc;