From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Subject: Re: [PATCH v5 15/17] dax: add struct iomap based DAX PMD support
Date: Mon, 10 Oct 2016 17:59:17 +0200
Message-ID: <20161010155917.GA19978@lst.de>
References: <1475874544-24842-1-git-send-email-ross.zwisler@linux.intel.com>
 <1475874544-24842-16-git-send-email-ross.zwisler@linux.intel.com>
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Cc: Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>, Matthew Wilcox <mawilcox-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>,
 Dave Chinner <david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org>, linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org,
 linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
 Andreas Dilger <adilger.kernel-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org>,
 Alexander Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>, Jan Kara <jack-IBi9RG/b67k@public.gmane.org>,
 linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
 linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
To: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
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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.

>  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.