From mboxrd@z Thu Jan  1 00:00:00 1970
From: axboe@fb.com (Jens Axboe)
Date: Wed, 14 Sep 2016 08:54:06 -0600
Subject: [PATCH, RFC] nvme: Do not test the read-ahead flag in cmd_flags
In-Reply-To: <20160914144715.GA29336@lst.de>
References: <30c2c70d-ec2d-607b-3f2f-5b3daa1754cd@sandisk.com>
 <20160914142306.GA28616@lst.de> <448dce16-78bf-938c-7968-d92006556ecb@fb.com>
 <20160914144715.GA29336@lst.de>
Message-ID: <4c27bf68-e2b3-2ad2-ddd3-8f5189ebec21@fb.com>

On 09/14/2016 08:47 AM, Christoph Hellwig wrote:
> On Wed, Sep 14, 2016@08:43:48AM -0600, Jens Axboe wrote:
>>> It's indeed a bug, but the questions is if why we shouldn't pass
>>> REQ_RAHEAD down to the request layer.  It's a useful attribute,
>>> and NVMe devices could make use of it.
>>
>> Indeed, seems a shame to lose this hint.
>
> It currently doesn't work.  But it would be useful to actually pass

Right, hence we lose it when mapping from a bio to a request.

> it through.  That being said we currently have a complete mess with
> the common vs request only flags, both about their placement in the
> enum and inclusion in the common mask.  Making it worse it seems
> like REQ_NOMERGE actually is used in both currently and not actually
> expecting propagation.

It would be nice to harden that.

-- 
Jens Axboe