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Date:   Tue, 2 Nov 2021 10:03:50 -0700
From:   Luis Chamberlain <mcgrof@kernel.org>
To:     Dan Williams <dan.j.williams@intel.com>
Cc:     Jens Axboe <axboe@kernel.dk>, Geoff Levand <geoff@infradead.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
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        vigneshr@ti.com, Vishal L Verma <vishal.l.verma@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        "Weiny, Ira" <ira.weiny@intel.com>,
        Keith Busch <kbusch@kernel.org>,
        Christoph Hellwig <hch@lst.de>,
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Subject: Re: [PATCH 03/13] nvdimm/btt: do not call del_gendisk() if not needed
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On Sun, Oct 31, 2021 at 10:47:22AM -0700, Dan Williams wrote:
> On Fri, Oct 15, 2021 at 4:53 PM Luis Chamberlain <mcgrof@kernel.org> wrote:
> >
> > We know we don't need del_gendisk() if we haven't added
> > the disk, so just skip it. This should fix a bug on older
> > kernels, as del_gendisk() became able to deal with
> > disks not added only recently, after the patch titled
> > "block: add flag for add_disk() completion notation".
> 
> Perhaps put this in:
> 
>     commit $abbrev_commit ("block: add flag for add_disk() completion notation")
> 
> ...format, but I can't seem to find that commit?

Indeed, that patch got dropped and it would seem Christoph preferred
a simpler approach with the new disk_live()

commit 40b3a52ffc5bc3b5427d5d35b035cfb19d03fdd6
Author: Christoph Hellwig <hch@lst.de>
Date:   Wed Aug 18 16:45:32 2021 +0200

    block: add a sanity check for a live disk in del_gendisk

> If you're touching the changelog how about one that clarifies the
> impact and drops "we"?
> "del_gendisk() is not required if the disk has not been added. On
> kernels prior to commit $abbrev_commit ("block: add flag for
> add_disk() completion notation")
> it is mandatory to not call del_gendisk() if the underlying device has
> not been through device_add()."
> 
> Fixes: 41cd8b70c37a ("libnvdimm, btt: add support for blk integrity")
> 
> With that you can add:
> 
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>

You got it.

  Luis