[PATCH v4 6/8] nvme: provide UUID value to userspace

From: Johannes Thumshirn
Date: Sun Jun 04 2017 - 06:38:09 EST


Now that we have a way for getting the UUID from a target, provide it
to userspace as well.

Unfortunately there is already a sysfs attribute called UUID which is
a misnomer as it holds the NGUID value. So instead of creating yet
another wrong name, create a new 'nguid' sysfs attribute for the
NGUID. For the UUID attribute add a check wheter the namespace has a
UUID assigned to it and return this or return the NGUID to maintain
backwards compatibility. This should give userspace a chance to catch
up.

Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
---
drivers/nvme/host/core.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 37047841da0e..3aa5b12680e5 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1887,11 +1887,28 @@ static ssize_t wwid_show(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR(wwid, S_IRUGO, wwid_show, NULL);

+static ssize_t nguid_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct nvme_ns *ns = nvme_get_ns_from_dev(dev);
+ return sprintf(buf, "%pU\n", ns->nguid);
+}
+static DEVICE_ATTR(nguid, S_IRUGO, nguid_show, NULL);
+
static ssize_t uuid_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct nvme_ns *ns = nvme_get_ns_from_dev(dev);
- return sprintf(buf, "%pU\n", ns->nguid);
+
+ /* For backward compatibility expose the NGUID to userspace if
+ * we have no UUID set
+ */
+ if (!memchr_inv(ns->uuid, 0, sizeof(ns->uuid))) {
+ printk_ratelimited(KERN_WARNING
+ "No UUID available providing old NGUID\n");
+ return sprintf(buf, "%pU\n", ns->nguid);
+ }
+ return sprintf(buf, "%pU\n", ns->uuid);
}
static DEVICE_ATTR(uuid, S_IRUGO, uuid_show, NULL);

@@ -1914,6 +1931,7 @@ static DEVICE_ATTR(nsid, S_IRUGO, nsid_show, NULL);
static struct attribute *nvme_ns_attrs[] = {
&dev_attr_wwid.attr,
&dev_attr_uuid.attr,
+ &dev_attr_nguid.attr,
&dev_attr_eui.attr,
&dev_attr_nsid.attr,
NULL,
@@ -1926,6 +1944,11 @@ static umode_t nvme_ns_attrs_are_visible(struct kobject *kobj,
struct nvme_ns *ns = nvme_get_ns_from_dev(dev);

if (a == &dev_attr_uuid.attr) {
+ if (!memchr_inv(ns->uuid, 0, sizeof(ns->uuid)) ||
+ !memchr_inv(ns->nguid, 0, sizeof(ns->nguid)))
+ return 0;
+ }
+ if (a == &dev_attr_nguid.attr) {
if (!memchr_inv(ns->nguid, 0, sizeof(ns->nguid)))
return 0;
}
--
2.12.0