nvmet: allow overriding the NVMe VS via configfs

Allow overriding the announced NVMe Version of a via configfs.

This is particularly helpful when debugging new features for the host
or target side without bumping the hard coded version (as the target
might not be fully compliant to the announced version yet).

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Guan Junxiong <guanjunxiong@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/configfs.c

@@ -650,8 +650,45 @@ out_unlock:
 
 CONFIGFS_ATTR(nvmet_subsys_, attr_allow_any_host);
 
+static ssize_t nvmet_subsys_version_show(struct config_item *item,
+					      char *page)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+
+	if (NVME_TERTIARY(subsys->ver))
+		return snprintf(page, PAGE_SIZE, "%d.%d.%d\n",
+				(int)NVME_MAJOR(subsys->ver),
+				(int)NVME_MINOR(subsys->ver),
+				(int)NVME_TERTIARY(subsys->ver));
+	else
+		return snprintf(page, PAGE_SIZE, "%d.%d\n",
+				(int)NVME_MAJOR(subsys->ver),
+				(int)NVME_MINOR(subsys->ver));
+}
+
+static ssize_t nvmet_subsys_version_store(struct config_item *item,
+					       const char *page, size_t count)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+	int major, minor, tertiary = 0;
+	int ret;
+
+
+	ret = sscanf(page, "%d.%d.%d\n", &major, &minor, &tertiary);
+	if (ret != 2 && ret != 3)
+		return -EINVAL;
+
+	down_write(&nvmet_config_sem);
+	subsys->ver = NVME_VS(major, minor, tertiary);
+	up_write(&nvmet_config_sem);
+
+	return count;
+}
+CONFIGFS_ATTR(nvmet_subsys_, version);
+
 static struct configfs_attribute *nvmet_subsys_attrs[] = {
 	&nvmet_subsys_attr_attr_allow_any_host,
+	&nvmet_subsys_attr_version,
 	NULL,
 };
 

include/linux/nvme.h

@@ -1085,4 +1085,8 @@ struct nvme_completion {
 #define NVME_VS(major, minor, tertiary) \
 	(((major) << 16) | ((minor) << 8) | (tertiary))
 
+#define NVME_MAJOR(ver)		((ver) >> 16)
+#define NVME_MINOR(ver)		(((ver) >> 8) & 0xff)
+#define NVME_TERTIARY(ver)	((ver) & 0xff)
+
 #endif /* _LINUX_NVME_H */