configfs: Introduce config_item_get_unless_zero()

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
[hch: minor style tweak]
Signed-off-by: Christoph Hellwig <hch@lst.de>

fs/configfs/item.c

@@ -138,6 +138,14 @@ struct config_item *config_item_get(struct config_item *item)
 }
 EXPORT_SYMBOL(config_item_get);
 
+struct config_item *config_item_get_unless_zero(struct config_item *item)
+{
+	if (item && kref_get_unless_zero(&item->ci_kref))
+		return item;
+	return NULL;
+}
+EXPORT_SYMBOL(config_item_get_unless_zero);
+
 static void config_item_cleanup(struct config_item *item)
 {
 	struct config_item_type *t = item->ci_type;