block: Add BdrvChildRole.stay_at_node
When the parents' child links are updated in bdrv_append() or
bdrv_replace_in_backing_chain(), this should affect all child links of
BlockBackends or other nodes, but not on child links held for other
purposes (like for setting permissions). This patch allows to control
the behaviour per BdrvChildRole.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
diff --git a/block.c b/block.c
index f72a67f..9e538a5 100644
--- a/block.c
+++ b/block.c
@@ -2853,6 +2853,9 @@
BdrvChild *c, *next, *to_c;
QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
+ if (c->role->stay_at_node) {
+ continue;
+ }
if (c->role == &child_backing) {
/* @from is generally not allowed to be a backing file, except for
* when @to is the overlay. In that case, @from may not be replaced
