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Date:   Wed, 9 Aug 2023 18:17:45 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     "Darrick J. Wong" <djwong@kernel.org>
Cc:     Christoph Hellwig <hch@lst.de>, Al Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        Namjae Jeon <linkinjeon@kernel.org>,
        Sungjong Seo <sj1557.seo@samsung.com>,
        Theodore Ts'o <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Konstantin Komarov <almaz.alexandrovich@paragon-software.com>,
        linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
        ntfs3@lists.linux.dev, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 06/13] xfs: close the RT and log block devices in
 xfs_free_buftarg
Message-ID: <20230809161745.GB2346@lst.de>
References: <20230808161600.1099516-1-hch@lst.de> <20230808161600.1099516-7-hch@lst.de> <20230809154532.GT11352@frogsfrogsfrogs>
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On Wed, Aug 09, 2023 at 08:45:32AM -0700, Darrick J. Wong wrote:
> >  	blkdev_issue_flush(btp->bt_bdev);
> >  	fs_put_dax(btp->bt_daxdev, btp->bt_mount);
> > +	/* the main block device is closed by kill_block_super */
> > +	if (bdev != btp->bt_mount->m_super->s_bdev)
> > +		blkdev_put(bdev, btp->bt_mount->m_super);
> 
> Hmm... I feel like this would be cleaner if the data dev buftarg could
> get its own refcount separate from super_block.s_bdev, but I looked
> through the code and couldn't identify a simple way to do that. Soo...

blkdev_put doesn't really drop a refcount, it closes the device.
It just happens to be misnamed, but Jan is looking into a series that
will as a side effect end up with a better name for this functionality.