rbd: prevent kernel stack blow up on rbd map
Mapping an image with a long parent chain (e.g. image foo, whose parent
is bar, whose parent is baz, etc) currently leads to a kernel stack
overflow, due to the following recursion in the reply path:
rbd_osd_req_callback()
rbd_obj_request_complete()
rbd_img_obj_callback()
rbd_img_parent_read_callback()
rbd_obj_request_complete()
...
Limit the parent chain to 16 images, which is ~5K worth of stack. When
the above recursion is eliminated, this limit can be lifted.
Fixes: http://tracker.ceph.com/issues/12538
Cc: stable@vger.kernel.org # 3.10+, needs backporting for < 4.2
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Josh Durgin <jdurgin@redhat.com>
1 file changed