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Date:   Thu, 21 Oct 2021 04:20:11 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Jane Chu <jane.chu@oracle.com>
Cc:     david@fromorbit.com, djwong@kernel.org, dan.j.williams@intel.com,
        hch@infradead.org, vishal.l.verma@intel.com, dave.jiang@intel.com,
        agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com,
        ira.weiny@intel.com, willy@infradead.org, vgoyal@redhat.com,
        linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev,
        linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 2/6] dax: prepare dax_direct_access() API with
 DAXDEV_F_RECOVERY flag
Message-ID: <YXFM64mFLN8dagrY@infradead.org>
References: <20211021001059.438843-1-jane.chu@oracle.com>
 <20211021001059.438843-3-jane.chu@oracle.com>
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On Wed, Oct 20, 2021 at 06:10:55PM -0600, Jane Chu wrote:
> @@ -156,8 +156,8 @@ bool generic_fsdax_supported(struct dax_device *dax_dev,
>  	}
>  
>  	id = dax_read_lock();
> -	len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
> -	len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
> +	len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn, 0);
> +	len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn, 0);

FYI, I have a series killing this code.  But either way please avoid
these overly long lines.

>  long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
> -		void **kaddr, pfn_t *pfn)
> +		void **kaddr, pfn_t *pfn, unsigned long flags)

API design: I'd usually expect flags before output paramters.