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 <[email protected]>
---
drivers/block/rbd.c | 30 ++++++++++--------------------
1 file changed, 10 insertions(+), 20 deletions(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index b85d52005a21..e818c2a6ffb1 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -4273,32 +4273,22 @@ static int rbd_dev_v2_parent_info(struct rbd_device
*rbd_dev)
}
/*
- * 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;
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);
+ /* refresh, careful to warn just once */
+ if (rbd_dev->parent_overlap)
+ rbd_warn(rbd_dev,
+ "clone now standalone (overlap became 0)");
} 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 with overlap 0");
+ /* initial probe */
+ rbd_warn(rbd_dev, "clone is standalone (overlap 0)");
}
}
+ rbd_dev->parent_overlap = overlap;
+
out:
ret = 0;
out_err:
--
1.9.3
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