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Date: Fri, 25 Aug 2017 09:01:04 +0200
From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvdimm@lists.01.org, jack@suse.cz, hch@lst.de,
        "Darrick J. Wong" <darrick.wong@oracle.com>
Subject: Re: [PATCH 1/2] xfs: cache dax_device lookup result
Message-ID: <20170825070104.GA9103@lst.de>
References: <150362134292.39142.1715377949592729029.stgit@dwillia2-desk3.amr.corp.intel.com> <150362134833.39142.12423673180125514125.stgit@dwillia2-desk3.amr.corp.intel.com>
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> +	bdev = bt->bt_bdev;
> +	if (!blk_queue_dax(bdev->bd_queue))
> +		return NULL;
> +
> +	if (!bt->bt_daxdev)
> +		bt->bt_daxdev = fs_dax_get_by_host(bdev->bd_disk->disk_name);
> +
> +	return bt->bt_daxdev;

Please do this at mount time.