From mboxrd@z Thu Jan  1 00:00:00 1970
From: Bart.VanAssche@wdc.com (Bart Van Assche)
Date: Wed, 30 Aug 2017 15:46:33 +0000
Subject: [GIT PULL] nvme update for Linux 4.14, take 2
In-Reply-To: <a798247e-cc89-f189-4ad9-92095a86106e@grimberg.me>
References: <20170829150507.rjixn6uf3id6kltx@infradead.org>
 <9a27048d-1252-985f-c905-b738d709b204@kernel.dk>
 <38ddd70f-3fec-09c0-dafb-eba1e8f9cc18@grimberg.me>
 <1504106914.2526.5.camel@wdc.com>
 <a798247e-cc89-f189-4ad9-92095a86106e@grimberg.me>
Message-ID: <1504107991.2526.16.camel@wdc.com>

On Wed, 2017-08-30@18:33 +0300, Sagi Grimberg wrote:
> > > I just realized that patch:
> > > --
> > > commit d352ae205d8b05f3f7558d10f474d8436581b3e2
> > > Author: Bart Van Assche <bart.vanassche at wdc.com>
> > > Date:   Thu Aug 17 16:23:03 2017 -0700
> > > 
> > >       blk-mq: Make blk_mq_reinit_tagset() calls easier to read
> > > 
> > >       Since blk_mq_ops.reinit_request is only called from inside
> > >       blk_mq_reinit_tagset(), make this function pointer an argument of
> > >       blk_mq_reinit_tagset() instead of a member of struct blk_mq_ops.
> > >       This patch does not change any functionality but makes
> > >       blk_mq_reinit_tagset() calls easier to read and to analyze.
> > > --
> > > 
> > > Makes it impossible for me to move controller reset flow to
> > > nvme-core without adding a trampoline (as the reinit_request
> > > is transport specific)...
> > 
> > Hello Sagi,
> > 
> > Sorry but I doubt that that patch makes it "impossible" to move controller
> > reset flow to the NVMe core. There are already several function pointers in
> > the nvme_ctrl_ops data structure and there is one such data structure per
> > transport. Had you already considered to add a function pointer to that
> > structure?
> 
> I have, that's the trampoline function that I was referring to, it feels
> a bit funny to have aa nvme core function that would look like:
> 
> int nvme_reinit_request()
> {
> 	return ctrl->ops->reinit_request()
> }
> 
> I can easily do that, but doesn't it defeat the purpose of blk_mq_ops?

I don't think so. Request reinitialization is an NVMe concept that is not used
by any other block driver, so why should the pointer to the reinitialization
function exist in blk_mq_ops?

Bart.