Re: [Qemu-devel] [PATCH v5 1/4] Add new block driver interface to add/delete a BDS's child

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Wen Congyang (wency@cn.fujitsu.com) wrote:
> On 10/08/2015 03:00 AM, Dr. David Alan Gilbert wrote:
> > * Wen Congyang (wency@cn.fujitsu.com) wrote:
> >> In some cases, we want to take a quorum child offline, and take
> >> another child online.
> > 
> > Hi,
> >   Have you checked the output of 'info block' after adding/deleting a child?
> > I'm using one of your older worlds (from a few months ago) and I found I had
> > to add a 
> > 
> >     bdrv_refresh_filename(bs);
> > 
> > to get the output of 'info block' to show the new child.
> > I don't see it in this version.
> 
> Max sent a patch series to drop BDS.filename, so I don't call bdrv_refresh_filename()
> here. If the BDS is not the top BDS, 'info block' still shows the wrong child.

Ah, so I guess you can just implement the exact_filename() function and that
will get it right?

Dave
> 
> Thanks
> Wen Congyang
> 
> > 
> > Dave
> > 
> > 
> >>
> >> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> >> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> >> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> >> Reviewed-by: Eric Blake <eblake@redhat.com>
> >> ---
> >>  block.c                   | 50 +++++++++++++++++++++++++++++++++++++++++++++++
> >>  include/block/block.h     |  5 +++++
> >>  include/block/block_int.h |  5 +++++
> >>  3 files changed, 60 insertions(+)
> >>
> >> diff --git a/block.c b/block.c
> >> index e815d73..1b25e43 100644
> >> --- a/block.c
> >> +++ b/block.c
> >> @@ -4265,3 +4265,53 @@ BlockAcctStats *bdrv_get_stats(BlockDriverState *bs)
> >>  {
> >>      return &bs->stats;
> >>  }
> >> +
> >> +/*
> >> + * 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 *parent_bs, BlockDriverState *child_bs,
> >> +                    Error **errp)
> >> +{
> >> +
> >> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
> >> +        error_setg(errp, "The BDS %s doesn't support adding a child",
> >> +                   bdrv_get_device_or_node_name(parent_bs));
> >> +        return;
> >> +    }
> >> +
> >> +    if (!QLIST_EMPTY(&child_bs->parents)) {
> >> +        error_setg(errp, "The BDS %s already has parent",
> >> +                   child_bs->node_name);
> >> +        return;
> >> +    }
> >> +
> >> +    parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
> >> +}
> >> +
> >> +void bdrv_del_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
> >> +                    Error **errp)
> >> +{
> >> +    BdrvChild *child;
> >> +
> >> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
> >> +        error_setg(errp, "The BDS %s doesn't support removing a child",
> >> +                   bdrv_get_device_or_node_name(parent_bs));
> >> +        return;
> >> +    }
> >> +
> >> +    QLIST_FOREACH(child, &parent_bs->children, next) {
> >> +        if (child->bs == child_bs) {
> >> +            break;
> >> +        }
> >> +    }
> >> +
> >> +    if (!child) {
> >> +        error_setg(errp, "BDS %s is not a child of %s",
> >> +                   bdrv_get_device_or_node_name(child_bs),
> >> +                   bdrv_get_device_or_node_name(parent_bs));
> >> +        return;
> >> +    }
> >> +
> >> +    parent_bs->drv->bdrv_del_child(parent_bs, child_bs, errp);
> >> +}
> >> diff --git a/include/block/block.h b/include/block/block.h
> >> index ef67353..665c56f 100644
> >> --- a/include/block/block.h
> >> +++ b/include/block/block.h
> >> @@ -616,4 +616,9 @@ void bdrv_flush_io_queue(BlockDriverState *bs);
> >>  
> >>  BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
> >>  
> >> +void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
> >> +                    Error **errp);
> >> +void bdrv_del_child(BlockDriverState *parent, BlockDriverState *child,
> >> +                    Error **errp);
> >> +
> >>  #endif
> >> diff --git a/include/block/block_int.h b/include/block/block_int.h
> >> index 2f2c47b..64cbc55 100644
> >> --- a/include/block/block_int.h
> >> +++ b/include/block/block_int.h
> >> @@ -288,6 +288,11 @@ struct BlockDriver {
> >>       */
> >>      int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
> >>  
> >> +    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
> >> +                           Error **errp);
> >> +    void (*bdrv_del_child)(BlockDriverState *parent, BlockDriverState *child,
> >> +                           Error **errp);
> >> +
> >>      QLIST_ENTRY(BlockDriver) list;
> >>  };
> >>  
> >> -- 
> >> 2.4.3
> >>
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> > .
> > 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK