linux-kernel - Re: [PATCH 2/2] block, bfq: delete "bfq" prefix from cgroup filenames

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Message-ID: <20190918151948.GL3084169@devbig004.ftw2.facebook.com>
Date:   Wed, 18 Sep 2019 08:19:48 -0700
From:   Tejun Heo <tj@...nel.org>
To:     Paolo Valente <paolo.valente@...aro.org>
Cc:     Jens Axboe <axboe@...nel.dk>,
        linux-block <linux-block@...r.kernel.org>,
        linux-kernel@...r.kernel.org, ulf.hansson@...aro.org,
        linus.walleij@...aro.org, bfq-iosched@...glegroups.com,
        oleksandr@...alenko.name, cgroups@...r.kernel.org,
        Angelo Ruocco <angeloruocco90@...il.com>
Subject: Re: [PATCH 2/2] block, bfq: delete "bfq" prefix from cgroup filenames

Hello,

On Wed, Sep 18, 2019 at 07:18:50AM +0200, Paolo Valente wrote:
> A solution that both fulfills userspace request and doesn't break
> anything for hypothetical users of the current interface already made
> it to mainline, and Linus liked it too.  It is:

Linus didn't like it.  The implementation was a bit nasty.  That was
why it became a subject in the first place.

> 19e9da9e86c4 ("block, bfq: add weight symlink to the bfq.weight cgroup parameter")
> 
> But it was then reverted on Tejun's request to do exactly what we
> don't want do any longer now:
> cf8929885de3 ("cgroup/bfq: revert bfq.weight symlink change")

Note that the interface was wrong at the time too.

> So, Jens, Tejun, can we please just revert that revert?

I think presenting both io.weight and io.bfq.weight interfaces are
probably the best course of action at this point but why does it have
to be a symlink?  What's wrong with just creating another file with
the same backing function?

Thanks.

-- 
tejun