Re: [PATCH 05/15] blkcg: update blkg_lookup_create to do locking

From: Tejun Heo
Date: Fri Aug 31 2018 - 19:09:09 EST

On Thu, Aug 30, 2018 at 09:53:46PM -0400, Dennis Zhou wrote:
> From: "Dennis Zhou (Facebook)" <dennisszhou@xxxxxxxxx>
> To know when to create a blkg, the general pattern is to do a
> blkg_lookup and if that fails, lock and then do a lookup again and if
> that fails finally create. It doesn't make much sense for everyone who
> wants to do creation to write this themselves.
> This changes blkg_lookup_create to do locking and implement this
> pattern. The old blkg_lookup_create is renamed to __blkg_lookup_create.
> If a call site wants to do its own error handling or already owns the
> queue lock, they can use __blkg_lookup_create.
> Signed-off-by: Dennis Zhou <dennisszhou@xxxxxxxxx>

It looks a bit weird w/o actual users, might be worthwhile to mention
that future patches will add users.

Acked-by: Tejun Heo <tj@xxxxxxxxxx>