libnvdimm, namespace: refactor uuid_show() into a namespace_to_uuid() helper

The ability to translate a generic struct device pointer into a
namespace uuid is a useful utility as we go to unify the blk and pmem
label scanning paths.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 9f4188c..0e62f46 100644 (file)
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -1032,22 +1032,27 @@ static ssize_t size_show(struct device *dev,
 }
 static DEVICE_ATTR(size, S_IRUGO, size_show, size_store);
 
-static ssize_t uuid_show(struct device *dev,
-               struct device_attribute *attr, char *buf)
+static u8 *namespace_to_uuid(struct device *dev)
 {
-       u8 *uuid;
-
        if (is_namespace_pmem(dev)) {
                struct nd_namespace_pmem *nspm = to_nd_namespace_pmem(dev);
 
-               uuid = nspm->uuid;
+               return nspm->uuid;
        } else if (is_namespace_blk(dev)) {
                struct nd_namespace_blk *nsblk = to_nd_namespace_blk(dev);
 
-               uuid = nsblk->uuid;
+               return nsblk->uuid;
        } else
-               return -ENXIO;
+               return ERR_PTR(-ENXIO);
+}
+
+static ssize_t uuid_show(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       u8 *uuid = namespace_to_uuid(dev);
 
+       if (IS_ERR(uuid))
+               return PTR_ERR(uuid);
        if (uuid)
                return sprintf(buf, "%pUb\n", uuid);
        return sprintf(buf, "\n");