Make bdrv_child_cb_attach() call bdrv_backing_attach() for children with
a COW role (and drop the reverse call from bdrv_backing_attach()), so it
can be used for any child (with a proper role set).
Because so far no child has a proper role set, we need a temporary new
callback for child_backing.attach that ensures bdrv_backing_attach() is
called for all COW children that do not have their role set yet.
(Also, move bdrv_child_cb_attach() down to group it with
bdrv_inherited_options().)
Signed-off-by: Max Reitz <address@hidden>
---
block.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)