Re: [PATCH 12/13] loop: remove lo_refcount and avoid lo_mutex in ->open / ->release
- To: Jan Kara <email@example.com>
- Cc: Christoph Hellwig <firstname.lastname@example.org>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, Dave Chinner <email@example.com>, Jens Axboe <firstname.lastname@example.org>, Josef Bacik <email@example.com>, Minchan Kim <firstname.lastname@example.org>, Nitin Gupta <email@example.com>, "Darrick J . Wong" <firstname.lastname@example.org>, Ming Lei <email@example.com>, firstname.lastname@example.org, email@example.com
- Subject: Re: [PATCH 12/13] loop: remove lo_refcount and avoid lo_mutex in ->open / ->release
- From: Christoph Hellwig <firstname.lastname@example.org>
- Date: Tue, 29 Mar 2022 08:39:21 +0200
- Message-id: <[🔎] 20220329063921.GA19778@lst.de>
- In-reply-to: <[🔎] email@example.com>
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On Mon, Mar 28, 2022 at 10:30:45AM +0200, Jan Kara wrote:
> On Fri 25-03-22 17:23:31, Christoph Hellwig wrote:
> > On Fri, Mar 25, 2022 at 07:54:15PM +0900, Tetsuo Handa wrote:
> > > > But for now I'd really prefer to stop moving the goalpost further and
> > > > further.
> > >
> > > Then, why not kill this code?
> > I think we should eventually do that, and I've indeed tested a patch
> > that is only cosmetically different. I wasn't really convinced we
> > should do it in this series, but if there is consensus that we should
> > do it now I can respin the series with a patch like this included.
> I'd defer it to a separate patchset. Because as much as the change to
> disallow LOOP_CLR_FD ioctl for used loop device makes sense, I'm not sure
> there isn't some framework using loop devices somewhere which relies on
> this just getting magically translated to setting LO_AUTOCLEAR flag. So IMO
> this has a big potential of userspace visible regression and as such I'd
> prefer doing it separately from the bugfixes.
At least my idea would not be to disallow LOOP_CLR_FD on a used block
devices as that would go back to the udev problems before Dave turned
it into a magic LO_AUTOCLEAR. But to remove the lo_refcnt check
entirely, as loop_clr_fd now is safe against concurrent users - it
has to anyway as there can be other users even without an open.
> Jan Kara <firstname.lastname@example.org>
> SUSE Labs, CR
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