- rbd_dev->parent_overlap = overlap;
- } else {
- rbd_warn(rbd_dev, "ignoring parent of clone with overlap 0\n");
+ }
+
+ /*
+ * We always update the parent overlap. If it's zero we
+ * treat it specially.
+ */
+ rbd_dev->parent_overlap = overlap;
+ smp_mb();
+ if (!overlap) {
+
+ /* A null parent_spec indicates it's the initial probe */
+
+ if (parent_spec) {
+ /*
+ * The overlap has become zero, so the clone
+ * must have been resized down to 0 at some
+ * point. Treat this the same as a flatten.
+ */
+ rbd_dev_parent_put(rbd_dev);
+ pr_info("%s: clone image now standalone\n",
+ rbd_dev->disk->disk_name);
+ } else {
+ /*
+ * For the initial probe, if we find the
+ * overlap is zero we just pretend there was
+ * no parent image.
+ */
+ rbd_warn(rbd_dev, "ignoring parent of "
+ "clone with overlap 0\n");
+ }