[PATCH 17/24] blkcg: implement blkcg_policy->on/offline_pd_fn() and blkcg_gq->online
Tejun Heo
tj at kernel.org
Wed Jan 2 20:37:18 UTC 2013
On Wed, Jan 02, 2013 at 02:38:28PM -0500, Vivek Goyal wrote:
> On Fri, Dec 28, 2012 at 12:35:39PM -0800, Tejun Heo wrote:
>
> [..]
> > diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
> > index 40f5b97..678e89e 100644
> > --- a/block/blk-cgroup.h
> > +++ b/block/blk-cgroup.h
> > @@ -106,12 +106,17 @@ struct blkcg_gq {
> > /* reference count */
> > int refcnt;
> >
> > + /* is this blkg online? protected by both blkcg and q locks */
> > + bool online;
> > +
>
> Hi Tejun,
>
> What does above mean? One needs to take one lock or both the locks to
> check/modify blkg->online.
Needs both locks to modify, so either lock is enough for checking.
--
tejun
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