rbd: fix rbd_dev_remove_parent()

In certain error paths, it is possible for an rbd device to have a
parent spec but no parent rbd_dev.  In rbd_dev_remove_parent() use
the parent field rather than parent_spec in determining whether to
try to remove any parent devices.  Use assertions to indicate that
any non-null parent pointer has parent_spec associated with it.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 0bae4e7..bc1e6e8 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -4994,7 +4994,7 @@ static void rbd_dev_release(struct device *dev)
 
 static void rbd_dev_remove_parent(struct rbd_device *rbd_dev)
 {
-       while (rbd_dev->parent_spec) {
+       while (rbd_dev->parent) {
                struct rbd_device *first = rbd_dev;
                struct rbd_device *second = first->parent;
                struct rbd_device *third;
@@ -5007,12 +5007,15 @@ static void rbd_dev_remove_parent(struct rbd_device *rbd_dev)
                        first = second;
                        second = third;
                }
+               rbd_assert(second);
                rbd_remove_all_snaps(second);
                rbd_bus_del_dev(second);
+               first->parent = NULL;
+               first->parent_overlap = 0;
+
+               rbd_assert(first->parent_spec);
                rbd_spec_put(first->parent_spec);
                first->parent_spec = NULL;
-               first->parent_overlap = 0;
-               first->parent = NULL;
        }
 }