[sheepdog] [PATCH] sheep: update node in cluster driver

[MORITA Kazutaka]

At Fri, 31 May 2013 18:35:59 +0800,
Liu Yuan wrote:
> 
> diff --git a/sheep/group.c b/sheep/group.c
> index b9399ee..f74ef10 100644
> --- a/sheep/group.c
> +++ b/sheep/group.c
> @@ -1242,6 +1242,7 @@ void update_node_size(struct sd_node *node)
>  	int idx = get_node_idx(cur_vinfo, node);
>  	assert(idx != -1);
>  	cur_vinfo->nodes[idx].space = node->space;
> +	sys->cdrv->update_node(node);
>  }

The current cluster driver model is:

 - Sheep triggers a node event with a cluster driver interface.
 - The cluster driver updates its internal state, and invokes a
   callback to notify the change to sheep.

In that sense, this fix is a bit weird to me.

I think a better fix is:

 1. make SD_OP_REWEIGHT a local request.
 2. call cdrv->update_node() in cluster_reweight().
 3. order the update_node event with other nonblocking events and call
    sd_update_node() as a callback of the update_node event.
 4. call update_node_size() and kick_node_recover() in sd_update_node()

Then, we can remove a SD_OP_UPDATE_SIZE operation and FIXME in the
local driver.

That being said, the current fix also looks correct to me (except the
local driver), so I'm fine with merging this code without changes.

Thanks,

Kazutaka