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From: Shiyang Ruan <ruansy.fnst@cn.fujitsu.com>
To: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: linux-xfs@vger.kernel.org, linux-nvdimm@lists.01.org,
	darrick.wong@oracle.com, hch@infradead.org, david@fromorbit.com,
	linux-kernel@vger.kernel.org, gujx@cn.fujitsu.com,
	qi.fuli@fujitsu.com
Subject: Re: [RFC PATCH v2 0/7] xfs: reflink & dedupe for fsdax (read/write path).
Date: Thu, 31 Oct 2019 12:54:54 +0800	[thread overview]
Message-ID: <2737c6f6-5cca-2b92-edff-fb9227ccc6d1@cn.fujitsu.com> (raw)
In-Reply-To: <20191030114818.emvmgfgqadiqintw@fiona>



On 10/30/19 7:48 PM, Goldwyn Rodrigues wrote:
> On 12:13 30/10, Shiyang Ruan wrote:
>> This patchset aims to take care of this issue to make reflink and dedupe
>> work correctly (actually in read/write path, there still has some problems,
>> such as the page->mapping and page->index issue, in mmap path) in XFS under
>> fsdax mode.
> 
> Have you managed to solve the problem of multi-mapped pages? I don't
> think we can include this until we solve that problem. This is the
> problem I faced when I was doing the btrfs dax support.

That problem still exists, didn't be solved in this patchset.  But I am 
also looking into it.  As you know, it's a bit difficult.

Since the iomap for cow is merged in for-next tree, I think it's time to 
update this in order to get some comments.

> 
> Suppose there is an extent shared with multiple files. You map data for
> both files. Which inode should page->mapping->host (precisely
> page->mapping) point to? As Dave pointed out, this needs to be fixed at
> the mm level, and will not only benefit dax with CoW but other
> areas such as overlayfs and possibly containers.

Yes, I will try to figure out a solution.
> 

-- 
Thanks,
Shiyang Ruan.

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  reply	other threads:[~2019-10-31  4:55 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-30  4:13 [RFC PATCH v2 0/7] xfs: reflink & dedupe for fsdax (read/write path) Shiyang Ruan
2019-10-30  4:13 ` [RFC PATCH v2 1/7] dax: Introduce dax_copy_edges() for COW Shiyang Ruan
2019-10-30  4:13 ` [RFC PATCH v2 2/7] dax: copy data before write Shiyang Ruan
2019-10-30  4:13 ` [RFC PATCH v2 3/7] dax: replace mmap entry in case of CoW Shiyang Ruan
2019-10-30  4:13 ` [RFC PATCH v2 4/7] fs: dedup file range to use a compare function Shiyang Ruan
2019-10-30  4:13 ` [RFC PATCH v2 5/7] dax: memcpy before zeroing range Shiyang Ruan
2019-10-30  4:13 ` [RFC PATCH v2 6/7] xfs: handle copy-on-write in fsdax write() path Shiyang Ruan
2019-10-30  4:13 ` [RFC PATCH v2 7/7] xfs: support dedupe for fsdax Shiyang Ruan
2019-10-30 11:48 ` [RFC PATCH v2 0/7] xfs: reflink & dedupe for fsdax (read/write path) Goldwyn Rodrigues
2019-10-31  4:54   ` Shiyang Ruan [this message]
2019-11-08  3:10 ` Shiyang Ruan
2019-11-08  3:30   ` Dan Williams
2019-11-14 20:24     ` Dave Chinner

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