From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
Received: from mail-yk0-f181.google.com (mail-yk0-f181.google.com [209.85.160.181])
	by kanga.kvack.org (Postfix) with ESMTP id A04606B0261
	for <linux-mm@kvack.org>; Wed, 30 Dec 2015 15:39:06 -0500 (EST)
Received: by mail-yk0-f181.google.com with SMTP id v14so71694621ykd.3
        for <linux-mm@kvack.org>; Wed, 30 Dec 2015 12:39:06 -0800 (PST)
Received: from mail-yk0-x22f.google.com (mail-yk0-x22f.google.com. [2607:f8b0:4002:c07::22f])
        by mx.google.com with ESMTPS id x64si48898079ywa.317.2015.12.30.12.39.05
        for <linux-mm@kvack.org>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Wed, 30 Dec 2015 12:39:05 -0800 (PST)
Received: by mail-yk0-x22f.google.com with SMTP id k129so142483792yke.0
        for <linux-mm@kvack.org>; Wed, 30 Dec 2015 12:39:05 -0800 (PST)
MIME-Version: 1.0
In-Reply-To: <56838FA3.5030909@oracle.com>
References: <1450899560-26708-1-git-send-email-ross.zwisler@linux.intel.com>
	<1450899560-26708-3-git-send-email-ross.zwisler@linux.intel.com>
	<56838FA3.5030909@oracle.com>
Date: Wed, 30 Dec 2015 12:39:04 -0800
Message-ID: <CAPcyv4jAO-jJ3VCOJRCc7zrQULED362SdZ88dDgN+zfQQEsfsA@mail.gmail.com>
Subject: Re: [PATCH v6 2/7] dax: support dirty DAX entries in radix tree
From: Dan Williams <dan.j.williams@intel.com>
Content-Type: text/plain; charset=UTF-8
Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: Bob Liu <bob.liu@oracle.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, "J. Bruce Fields" <bfields@fieldses.org>, Theodore Ts'o <tytso@mit.edu>, Alexander Viro <viro@zeniv.linux.org.uk>, Andreas Dilger <adilger.kernel@dilger.ca>, Dave Chinner <david@fromorbit.com>, Ingo Molnar <mingo@redhat.com>, Jan Kara <jack@suse.com>, Jeff Layton <jlayton@poochiereds.net>, Matthew Wilcox <willy@linux.intel.com>, Thomas Gleixner <tglx@linutronix.de>, linux-ext4 <linux-ext4@vger.kernel.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Linux MM <linux-mm@kvack.org>, linux-nvdimm <linux-nvdimm@ml01.01.org>, X86 ML <x86@kernel.org>, XFS Developers <xfs@oss.sgi.com>, Andrew Morton <akpm@linux-foundation.org>, Matthew Wilcox <matthew.r.wilcox@intel.com>, Dave Hansen <dave.hansen@linux.intel.com>

On Wed, Dec 30, 2015 at 12:02 AM, Bob Liu <bob.liu@oracle.com> wrote:
> Hi Ross,
>
> On 12/24/2015 03:39 AM, Ross Zwisler wrote:
>> Add support for tracking dirty DAX entries in the struct address_space
>> radix tree.  This tree is already used for dirty page writeback, and it
>> already supports the use of exceptional (non struct page*) entries.
>>
>> In order to properly track dirty DAX pages we will insert new exceptional
>> entries into the radix tree that represent dirty DAX PTE or PMD pages.
>
> I may get it wrong, but there is "struct page" for persistent memory after
> "[PATCH v4 00/18]get_user_pages() for dax pte and pmd mappings".
> So why not just add "struct page" to radix tree directly just like normal page cache?
>
> Then we don't need to deal with any exceptional entries and special writeback.

That "struct page" is optional and fsync/msync needs to operate in its absence.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>