linux-kernel - Re: [PATCH v2 08/11] block: sed-opal: ioctl for writing to shadow mbr

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Message-ID: <20180320220907.zdzf7baag6haaonm@sbauer-Z170X-UD5>
Date:   Tue, 20 Mar 2018 16:09:08 -0600
From:   Scott Bauer <scott.bauer@...el.com>
To:     Jonas Rabenstein <jonas.rabenstein@...dium.uni-erlangen.de>
Cc:     Christoph Hellwig <hch@....de>,
        Jonathan Derrick <jonathan.derrick@...el.com>,
        Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 08/11] block: sed-opal: ioctl for writing to shadow mbr

On Tue, Mar 20, 2018 at 10:36:04AM +0100, Jonas Rabenstein wrote:
> On Mon, Mar 19, 2018 at 08:52:24PM +0100, Christoph Hellwig wrote:
> > On Mon, Mar 19, 2018 at 07:36:50PM +0100, Jonas Rabenstein wrote:
> > > Allow modification of the shadow mbr. If the shadow mbr is not marked as
> > > done, this data will be presented read only as the device content. Only
> > > after marking the shadow mbr as done and unlocking a locking range the
> > > actual content is accessible.
> > 
> > I hate doing this as an ioctls.  Can we make this a sysfs binary file
> > so that people can use dd or cat to write the shadow mbr?
> I already thought about providing a sysfs interface for all that instead
> of using ioctls. But as I am pretty new to kernel programming I do not
> have all the required insight. Especially, as writing the mbr requires
> the sed-opal password I am unsure how a clean sysfs interface to provide
> the password together with a simple dd would look like.
> Moreover I already have a patch that changes the 'void *data' argument
> to setup_opal_dev to a kobject pointer. As far as I know, this is the
> first step to get into the sysfs hierarchy. But as I do not have access
> to an NVMe drive and have no idea about its implementation, this change
> works only for the scsi side.

Post what you have as an RFC (review for comment) and I will test for the NVMe
side, and or start a port for NVMe. It doesn't have to be perfect since you're
sending it out as RFC. It's just a base for us to test/look at to see if we
still like the sysfs way.