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Date: Mon, 10 Oct 2016 16:06:19 -0600
From: Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: Re: [PATCH v5 15/17] dax: add struct iomap based DAX PMD support
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To: Christoph Hellwig <hch@lst.de>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>, linux-kernel@vger.kernel.org, Theodore Ts'o <tytso@mit.edu>, Alexander Viro <viro@zeniv.linux.org.uk>, Andreas Dilger <adilger.kernel@dilger.ca>, Andrew Morton <akpm@linux-foundation.org>, Dan Williams <dan.j.williams@intel.com>, Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.com>, Matthew Wilcox <mawilcox@microsoft.com>, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org, linux-xfs@vger.kernel.org

On Mon, Oct 10, 2016 at 05:59:17PM +0200, Christoph Hellwig wrote:
> On Fri, Oct 07, 2016 at 03:09:02PM -0600, Ross Zwisler wrote:
> > -	if (RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD)
> > +	if ((unsigned long)entry & RADIX_DAX_PMD)
> 
> Please introduce a proper inline helper that mask all the possible type
> bits out of the radix tree entry, and use them wherever you do the
> open cast.

Sure, will do.

> >  restart:
> >  	spin_lock_irq(&mapping->tree_lock);
> >  	entry = get_unlocked_mapping_entry(mapping, index, &slot);
> > +
> > +	if (entry) {
> > +		if (size_flag & RADIX_DAX_PMD) {
> > +			if (!radix_tree_exceptional_entry(entry) ||
> > +			    !((unsigned long)entry & RADIX_DAX_PMD)) {
> > +				entry = ERR_PTR(-EEXIST);
> > +				goto out_unlock;
> > +			}
> > +		} else { /* trying to grab a PTE entry */
> > +			if (radix_tree_exceptional_entry(entry) &&
> > +			    ((unsigned long)entry & RADIX_DAX_PMD) &&
> > +			    ((unsigned long)entry &
> > +			     (RADIX_DAX_HZP|RADIX_DAX_EMPTY))) {
> 
> And when we do these cases N times next to each other we should
> have a local variable the valid flag bits of entry.

Okay, will fix.