[Qemu-block] Is the use of bdrv_getlength() in quorum_co_flush() kosher?

[Markus Armbruster]

Have a look at quorum_co_flush():

            quorum_report_bad(QUORUM_OP_TYPE_FLUSH, 0,
                              bdrv_getlength(s->children[i]->bs),
                              s->children[i]->bs->node_name, result);

bdrv_getlength() can fail.  Does it do the right thing then?