Feedback-ID: iac594737:Fastmail
Date:   Mon, 30 Jan 2023 14:22:39 -0500
From:   Demi Marie Obenour <demi@invisiblethingslab.com>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Jens Axboe <axboe@kernel.dk>,
        Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= 
        <marmarek@invisiblethingslab.com>, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/7] block: Support creating a struct file from a
 block device
Message-ID: <Y9gZAJGgdjFtsm9I@itl-email>
References: <20230126033358.1880-1-demi@invisiblethingslab.com>
 <20230126033358.1880-2-demi@invisiblethingslab.com>
 <Y9d692WEX/ZvBhXI@infradead.org>
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Date: Mon, 30 Jan 2023 14:22:39 -0500
From: Demi Marie Obenour <demi@invisiblethingslab.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>,
	Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= <marmarek@invisiblethingslab.com>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/7] block: Support creating a struct file from a
 block device

On Mon, Jan 30, 2023 at 12:08:23AM -0800, Christoph Hellwig wrote:
> On Wed, Jan 25, 2023 at 10:33:53PM -0500, Demi Marie Obenour wrote:
> > The newly added blkdev_get_file() function allows kernel code to create
> > a struct file for any block device.  The main use-case is for the
> > struct file to be exposed to userspace as a file descriptor.  A future
> > patch will modify the DM_DEV_CREATE_CREATE ioctl to allow userspace to
> > get a file descriptor to the newly created block device, avoiding nasty
> > race conditions.
>=20
> NAK.  Do not add wierd side-way interfaces to the block layer.

What do you recommend instead?  This solves a real problem for
device-mapper users and I am not aware of a better solution.
--=20
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

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