zram: use class_groups instead of class_attrs

The class_attrs pointer is long depreciated, and is about to be finally
removed, so move to use the class_groups pointer instead.

Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/block/zram/zram_drv.c

@@ -1272,6 +1272,13 @@ static int zram_remove(struct zram *zram)
 }
 
 /* zram-control sysfs attributes */
+
+/*
+ * NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a
+ * sense that reading from this file does alter the state of your system -- it
+ * creates a new un-initialized zram device and returns back this device's
+ * device_id (or an error code if it fails to create a new device).
+ */
 static ssize_t hot_add_show(struct class *class,
 			struct class_attribute *attr,
 			char *buf)
@@ -1286,6 +1293,7 @@ static ssize_t hot_add_show(struct class *class,
 		return ret;
 	return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
 }
+static CLASS_ATTR(hot_add, 0400, hot_add_show, NULL);
 
 static ssize_t hot_remove_store(struct class *class,
 			struct class_attribute *attr,
@@ -1316,23 +1324,19 @@ static ssize_t hot_remove_store(struct class *class,
 	mutex_unlock(&zram_index_mutex);
 	return ret ? ret : count;
 }
+static CLASS_ATTR_WO(hot_remove);
 
-/*
- * NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a
- * sense that reading from this file does alter the state of your system -- it
- * creates a new un-initialized zram device and returns back this device's
- * device_id (or an error code if it fails to create a new device).
- */
-static struct class_attribute zram_control_class_attrs[] = {
-	__ATTR(hot_add, 0400, hot_add_show, NULL),
-	__ATTR_WO(hot_remove),
-	__ATTR_NULL,
+static struct attribute *zram_control_class_attrs[] = {
+	&class_attr_hot_add.attr,
+	&class_attr_hot_remove.attr,
+	NULL,
 };
+ATTRIBUTE_GROUPS(zram_control_class);
 
 static struct class zram_control_class = {
 	.name		= "zram-control",
 	.owner		= THIS_MODULE,
-	.class_attrs	= zram_control_class_attrs,
+	.class_groups	= zram_control_class_groups,
 };
 
 static int zram_remove_cb(int id, void *ptr, void *data)