rbd: do not treat standalone as flatten (cf32bd9c) · Commits · 戴 / test

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>

drivers/block/rbd.c

+10 −20

Original line number	Diff line number	Diff line
		@@ -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:

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