From: "Elliott, Robert (Persistent Memory)" <elliott@hpe.com>
Subject: RE: [PATCH v6 3/7] mm: add find_get_entries_tag()
Date: Thu, 24 Dec 2015 00:28:24 +0000
Message-ID: <94D0CD8314A33A4D9D801C0FE68B40295BEC9A58@G9W0745.americas.hpqcorp.net>
References: <1450899560-26708-1-git-send-email-ross.zwisler@linux.intel.com>
 <1450899560-26708-4-git-send-email-ross.zwisler@linux.intel.com>
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Cc: Dave Hansen <dave.hansen@linux.intel.com>, Dave Chinner
	<david@fromorbit.com>, "J. Bruce Fields" <bfields@fieldses.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>, Andreas Dilger
	<adilger.kernel@dilger.ca>, "H. Peter Anvin" <hpa@zytor.com>, Jeff Layton
	<jlayton@poochiereds.net>, "linux-nvdimm@lists.01.org"
	<linux-nvdimm@lists.01.org>, "x86@kernel.org" <x86@kernel.org>, Ingo Molnar
	<mingo@redhat.com>, "linux-ext4@vger.kernel.org"
	<linux-ext4@vger.kernel.org>, "xfs@oss.sgi.com" <xfs@oss.sgi.com>, Alexander
 Viro <viro@zeniv.linux.org.uk>, Thomas Gleixner <tglx@linutronix.de>,
	Theodore Ts'o <tytso@mit.edu>, Jan Kara <jack@suse.com>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>, Andrew
 Morton <akpm@linux-foundation.org>, Matthew Wilcox
	<matthew.r.wilcox@intel.com>
To: Ross Zwisler <ross.zwisler@linux.intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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> -----Original Message-----
> From: Linux-nvdimm [mailto:linux-nvdimm-bounces@lists.01.org] On Behalf O=
f
> Ross Zwisler
> Sent: Wednesday, December 23, 2015 1:39 PM
> Subject: [PATCH v6 3/7] mm: add find_get_entries_tag()
>=20
...
> diff --git a/mm/filemap.c b/mm/filemap.c
...
> +unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t sta=
rt,
> +			int tag, unsigned int nr_entries,
> +			struct page **entries, pgoff_t *indices)
> +{
> +	void **slot;
> +	unsigned int ret =3D 0;
...
> +	radix_tree_for_each_tagged(slot, &mapping->page_tree,
> +				   &iter, start, tag) {
...
> +		indices[ret] =3D iter.index;
> +		entries[ret] =3D page;
> +		if (++ret =3D=3D nr_entries)
> +			break;
> +	}

Using >=3D would provide more safety from buffer overflow
problems in case ret ever jumped ahead by more than one.
---
Robert Elliott, HPE Persistent Memory

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