On 09/01/2015 01:40 AM, Eric Blake wrote: > On 08/11/2015 01:51 AM, Wen Congyang wrote: >> In some cases, we want to take a quorum child offline, and take >> another child online. >> >> Signed-off-by: Wen Congyang <we...@cn.fujitsu.com> >> Signed-off-by: zhanghailiang <zhang.zhanghaili...@huawei.com> >> Signed-off-by: Gonglei <arei.gong...@huawei.com> >> Reviewed-by: Alberto Garcia <be...@igalia.com> >> --- >> block.c | 43 +++++++++++++++++++++++++++++++++++++++++++ >> include/block/block.h | 4 ++++ >> include/block/block_int.h | 5 +++++ >> 3 files changed, 52 insertions(+) >> > >> + * Hot add/remove a BDS's child. So the user can take a child offline when >> + * it is broken and take a new child online >> + */ >> +void bdrv_add_child(BlockDriverState *bs, QDict *options, Error **errp) >> +{ >> + >> + if (!bs->drv || !bs->drv->bdrv_add_child) { >> + error_setg(errp, "The BDS %s doesn't support adding a child", >> + bdrv_get_device_or_node_name(bs)); >> + return; >> + } >> + >> + bs->drv->bdrv_add_child(bs, options, errp); > > Should this also check that bs is not already a child of something? Or > a bit looser, we may want to allow a BDS to be a child of multiple trees > (a common shared backing file), but we still definitely don't want to > allow nonsensical loops such as trying to make a BDS be hot-added as its > own child. >
bs is parent, and the child is options, and will be opened by the parent. So there is no need to check it. Thanks Wen Congyang