block: Factor out should_update_child()

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
stable-2.9
Kevin Wolf 2017-03-01 17:30:41 +01:00
parent 067acf28d1
commit d0ac038025
1 changed files with 27 additions and 15 deletions

42
block.c
View File

@ -2886,28 +2886,40 @@ void bdrv_close_all(void)
assert(QTAILQ_EMPTY(&all_bdrv_states));
}
static bool should_update_child(BdrvChild *c, BlockDriverState *to)
{
BdrvChild *to_c;
if (c->role->stay_at_node) {
return false;
}
if (c->role == &child_backing) {
/* If @from is a backing file of @to, ignore the child to avoid
* creating a loop. We only want to change the pointer of other
* parents. */
QLIST_FOREACH(to_c, &to->children, next) {
if (to_c == c) {
break;
}
}
if (to_c) {
return false;
}
}
return true;
}
static void change_parent_backing_link(BlockDriverState *from,
BlockDriverState *to)
{
BdrvChild *c, *next, *to_c;
BdrvChild *c, *next;
QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
if (c->role->stay_at_node) {
if (!should_update_child(c, to)) {
continue;
}
if (c->role == &child_backing) {
/* If @from is a backing file of @to, ignore the child to avoid
* creating a loop. We only want to change the pointer of other
* parents. */
QLIST_FOREACH(to_c, &to->children, next) {
if (to_c == c) {
break;
}
}
if (to_c) {
continue;
}
}
bdrv_ref(to);
/* FIXME Are we sure that bdrv_replace_child() can't run into