From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yb0-f197.google.com (mail-yb0-f197.google.com [209.85.213.197]) by kanga.kvack.org (Postfix) with ESMTP id 126A46B0003 for ; Wed, 30 May 2018 11:49:38 -0400 (EDT) Received: by mail-yb0-f197.google.com with SMTP id u15-v6so3644030ybi.19 for ; Wed, 30 May 2018 08:49:38 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id k18-v6sor6414311ywa.300.2018.05.30.08.49.37 for (Google Transport Security); Wed, 30 May 2018 08:49:37 -0700 (PDT) Date: Wed, 30 May 2018 08:49:33 -0700 From: Tejun Heo Subject: Re: [PATCH 01/13] block: add bi_blkg to the bio for cgroups Message-ID: <20180530154933.GI1351649@devbig577.frc2.facebook.com> References: <20180529211724.4531-1-josef@toxicpanda.com> <20180529211724.4531-2-josef@toxicpanda.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180529211724.4531-2-josef@toxicpanda.com> Sender: owner-linux-mm@kvack.org List-ID: To: Josef Bacik Cc: axboe@kernel.dk, kernel-team@fb.com, linux-block@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Josef Bacik On Tue, May 29, 2018 at 05:17:12PM -0400, Josef Bacik wrote: > From: Josef Bacik > > Currently io.low uses a bi_cg_private to stash its private data for the > blkg, however other blkcg policies may want to use this as well. Since > we can get the private data out of the blkg, move this to bi_blkg in the > bio and make it generic, then we can use bio_associate_blkg() to attach > the blkg to the bio. > > Theoretically we could simply replace the bi_css with this since we can > get to all the same information from the blkg, however you have to > lookup the blkg, so for example wbc_init_bio() would have to lookup and > possibly allocate the blkg for the css it was trying to attach to the > bio. This could be problematic and result in us either not attaching > the css at all to the bio, or falling back to the root blkcg if we are > unable to allocate the corresponding blkg. > > So for now do this, and in the future if possible we could just replace > the bi_css with bi_blkg and update the helpers to do the correct > translation. > > Signed-off-by: Josef Bacik Acked-by: Tejun Heo Thanks. -- tejun