Re: [PATCH 02/15] blkcg: delay blkg destruction until after writeback has finished

From: Dennis Zhou
Date: Fri Aug 31 2018 - 16:19:19 EST

Hi Josef,

On Fri, Aug 31, 2018 at 11:27:07AM -0400, Josef Bacik wrote:
> So the general approach is correct, but it's sort of confusing because you are
> using nr_cgwbs as a reference counter, because it's set at 1 at blkg creation
> time regardless of wether or not there's an assocated wb cg. So instead why not
> just have a refcount_t ref, set it to 1 on creation and make the wb cg take a
> ref when it's attached, and then just do the get/put like normal and cleanup as
> you have below? What you are doing is a reference counter masquerading as a
> count of the wb cg's, just add full ref counting to the blkcg and call it a day,
> it'll be much less confusing. Thanks,

Yeah, that makes more sense. I've switched to using refcount_t and
renamed it to wbcg_refcnt. The corresponding actions have been renamed.

I've also fixed the kbuild error in v2.