[libvirt] [PATCH] rbd: Open in Read-Only mode when refreshing a volume

[John Ferlan]

On 01/28/2016 05:20 AM, Wido den Hollander wrote:
> By opening a RBD volume in Read-Only we do not register a
> watcher on the header object inside the Ceph cluster.
> 
> Refreshing a volume only calls rbd_stat() which is a operation
> which does not write to a RBD image.
> 
> This allows us to use a cephx user which has no write
> permissions if we would want to use the libvirt storage pool
> for informational purposes only.
> 
> It also saves us a write into the Ceph cluster which should
> speed up refreshing a RBD pool.
> 
> rbd_open_read_only() is available in all librbd versions which
> also support rbd_open().
> 
> Signed-off-by: Wido den Hollander <wido at widodh.nl>
> ---
>  src/storage/storage_backend_rbd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

ACK - and pushed

John