From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Subject: Re: [PATCH v2 0/29] block: Make blkdev_get_by_*() return
	handle
Date: Mon, 28 Aug 2023 07:22:21 -0700
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To: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
Cc: Dave Kleikamp <shaggy-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, jfs-discussion-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, "Darrick J. Wong" <djwong-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Joseph Qi <joseph.qi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, target-devel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Jack Wang <jinpu.wang-vEVw2sk9H7kAvxtiuMwx3w@public.gmane.org>, Alasdair Kergon <agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, drbd-dev-cunTk1MwBs8qoQakbn7OcQ@public.gmane.org, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Sergey Senozhatsky <senozhatsky-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, xen-devel-GuqFBffKawtpuQazS67q72D2FQJk+8+b@public.gmane.org, Gao Xiang <xiang-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Christian Borntraeger <borntraeger-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org>, Kent Overstreet <kent.overstreet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Sven Schnelle <svens-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org>, Christian Brauner <brauner-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mike Snitzer <snitzer-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Chao Yu <chao-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Joern Engel <joern@lazyba>

On Fri, Aug 25, 2023 at 03:47:56PM +0200, Jan Kara wrote:
> I can see the appeal of not having to introduce the new bdev_handle type
> and just using struct file which unifies in-kernel and userspace block
> device opens. But I can see downsides too - the last fput() happening from
> task work makes me a bit nervous whether it will not break something
> somewhere with exclusive bdev opens. Getting from struct file to bdev is
> somewhat harder but I guess a helper like F_BDEV() would solve that just
> fine.
> 
> So besides my last fput() worry about I think this could work and would be
> probably a bit nicer than what I have. But before going and redoing the whole
> series let me gather some more feedback so that we don't go back and forth.
> Christoph, Christian, Jens, any opinion?

I did think about the file a bit.  The fact that we'd need something
like an anon_file for the by_dev open was always a huge turn off for
me, but maybe my concern is overblown.  Having a struct file would
actually be really useful for a bunch of users.