block: Support inactive nodes in blk_insert_bs()

block: Support inactive nodes in blk_insert_bs()

Device models have a relatively complex way to set up their block
backends, in which blk_attach_dev() sets blk->disable_perm = true.
We want to support inactive images in exports, too, so that
qemu-storage-daemon can be used with migration. Because they don't use
blk_attach_dev(), they need another way to set this flag. The most
convenient is to do this automatically when an inactive node is attached
to a BlockBackend that can be inactivated.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20250204211407.381505-10-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>