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From:   Christoph Hellwig <hch@lst.de>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Tim Waugh <tim@cyberelk.net>, Borislav Petkov <bp@alien8.de>,
        Jan Kara <jack@suse.com>, linux-block@vger.kernel.org,
        linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: stop using ioctl_by_bdev for file system access to CDROMs v2
Date:   Sat, 25 Apr 2020 09:56:59 +0200
Message-Id: <20200425075706.721917-1-hch@lst.de>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Jens,

except for the DASD case under discussion the last users of ioctl_by_bdev
are the file system drivers that want to query CDROM information using
ioctls.  This series switches them to use function calls directly into
the CDROM midlayer instead, which implies:

 - adding a cdrom_device_info pointer to the gendisk, so that file systems
   can find it without going to the low-level driver first
 - ensuring that the CDROM midlayer (which isn't a lot of code) is built
   in if the file systems are built in so that they can actually call the
   exported functions

Changes since v1:
 - fix up the no-CDROM error case in isofs_get_last_session to return 0
   instead of -EINVAL.