If the clone is resized down to 0, it becomes standalone. If such
resize is carried over while an image is mapped we would detect this
and call rbd_dev_parent_put() which means "let go of all parent state,
including the spec(s) of parent images(s)". This leads to a mismatch
between "rbd info" and sysfs parent fields, so a fix is in order.
# rbd create --image-format 2 --size 1 foo
# rbd snap create foo@snap
# rbd snap protect foo@snap
# rbd clone foo@snap bar
# DEV=$(rbd map bar)
# rbd resize --allow-shrink --size 0 bar
# rbd resize --size 1 bar
# rbd info bar | grep parent
parent: rbd/foo@snap
Before:
# cat /sys/bus/rbd/devices/0/parent
(no parent image)
After:
# cat /sys/bus/rbd/devices/0/parent
pool_id 0
pool_name rbd
image_id
10056b8b4567
image_name foo
snap_id 2
snap_name snap
overlap 0
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
Reviewed-by: Josh Durgin <jdurgin@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
- * We always update the parent overlap. If it's zero we
- * treat it specially.
+ * We always update the parent overlap. If it's zero we issue
+ * a warning, as we will proceed as if there was no parent.
- rbd_dev->parent_overlap = overlap;
-
- /* A null parent_spec indicates it's the initial probe */
-
- /*
- * 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);
+ /* refresh, careful to warn just once */
+ if (rbd_dev->parent_overlap)
+ rbd_warn(rbd_dev,
+ "clone now standalone (overlap became 0)");
- /*
- * 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 with overlap 0");
+ /* initial probe */
+ rbd_warn(rbd_dev, "clone is standalone (overlap 0)");
+ rbd_dev->parent_overlap = overlap;
+