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Date:   Mon, 12 Aug 2019 13:17:35 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Matthew Bobrowski <mbobrowski@mbobrowski.org>,
        linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        jack@suse.cz, tytso@mit.edu, riteshh@linux.ibm.com
Subject: Re: [PATCH 1/5] ext4: introduce direct IO read code path using iomap
 infrastructure
Message-ID: <20190812201735.GA5307@bombadil.infradead.org>
References: <cover.1565609891.git.mbobrowski@mbobrowski.org>
 <3e83a70c4442c6aeb15b7913c39f853e7386a3c3.1565609891.git.mbobrowski@mbobrowski.org>
 <20190812171835.GB24564@infradead.org>
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On Mon, Aug 12, 2019 at 10:18:35AM -0700, Christoph Hellwig wrote:
> >  		return -EIO;
> >  
> >  	if (!iov_iter_count(to))
> >  		return 0; /* skip atime */
> >  
> >  #ifdef CONFIG_FS_DAX
> > -	if (IS_DAX(file_inode(iocb->ki_filp)))
> > +	if (IS_DAX(inode))
> >  		return ext4_dax_read_iter(iocb, to);
> >  #endif
> 
> Same here.

It doesn't even need IS_ENABLED.

include/linux/fs.h:#define IS_DAX(inode)                ((inode)->i_flags & S_DAX)

#ifdef CONFIG_FS_DAX
#define S_DAX           8192    /* Direct Access, avoiding the page cache */
#else
#define S_DAX           0       /* Make all the DAX code disappear */
#endif