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Date:   Thu, 30 Apr 2020 15:13:52 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Stefan Haberland <sth@linux.ibm.com>
Cc:     axboe@kernel.dk, hch@lst.de, linux-block@vger.kernel.org,
        hoeppner@linux.ibm.com, linux-s390@vger.kernel.org,
        heiko.carstens@de.ibm.com, gor@linux.ibm.com,
        borntraeger@de.ibm.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] s390/dasd: remove ioctl_by_bdev from DASD driver
Message-ID: <20200430131351.GA24813@lst.de>
References: <20200430111754.98508-1-sth@linux.ibm.com> <20200430111754.98508-2-sth@linux.ibm.com>
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On Thu, Apr 30, 2020 at 01:17:54PM +0200, Stefan Haberland wrote:
> Remove the calls to ioctl_by_bdev from the DASD partition detection code
> to enable the removal of the specific code.
> 
> To do so reuse the gendisk private_data pointer and not only provide a
> pointer to the devmap but provide a new structure containing a pointer
> to the devmap as well as all required information for the partition
> detection. This makes it independent from the dasd_information2_t
> structure.

I think sharing the data structure in private data is pretty dangerous.
In the meantime I thought of another idea - the partition code could
do a symbol_get of a symbol exported by the dasd driver and use that
to query the information.