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From: Ruan Shiyang <ruansy.fnst@cn.fujitsu.com>
To: Christoph Hellwig <hch@lst.de>
Cc: jack@suse.cz, darrick.wong@oracle.com, linux-nvdimm@lists.01.org,
	david@fromorbit.com, linux-kernel@vger.kernel.org,
	linux-xfs@vger.kernel.org, ocfs2-devel@oss.oracle.com,
	viro@zeniv.linux.org.uk, Goldwyn Rodrigues <rgoldwyn@suse.com>,
	linux-fsdevel@vger.kernel.org, dan.j.williams@intel.com,
	linux-btrfs@vger.kernel.org
Subject: Re: [Ocfs2-devel] [PATCH 5/7] fsdax: Dedup file range to use a compare function
Date: Tue, 9 Feb 2021 17:15:13 +0800	[thread overview]
Message-ID: <9193e305-22a1-3928-0675-af1cecd28942@cn.fujitsu.com> (raw)
In-Reply-To: <20210208151920.GE12872@lst.de>



On 2021/2/8 下午11:19, Christoph Hellwig wrote:
> On Mon, Feb 08, 2021 at 01:09:22AM +0800, Shiyang Ruan wrote:
>> With dax we cannot deal with readpage() etc. So, we create a
>> funciton callback to perform the file data comparison and pass
> 
> s/funciton/function/g
> 
>> +#define MIN(a, b) (((a) < (b)) ? (a) : (b))
> 
> This should use the existing min or min_t helpers.
> 
> 
>>   int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
>>   				  struct file *file_out, loff_t pos_out,
>> -				  loff_t *len, unsigned int remap_flags)
>> +				  loff_t *len, unsigned int remap_flags,
>> +				  compare_range_t compare_range_fn)
> 
> Can we keep generic_remap_file_range_prep as-is, and add a new
> dax_remap_file_range_prep, both sharing a low-level
> __generic_remap_file_range_prep implementation?  And for that
> implementation I'd also go for classic if/else instead of the function
> pointer.

The dax dedupe comparison need the iomap_ops pointer as argument, so my 
understanding is that we don't modify the argument list of 
generic_remap_file_range_prep(), but move its code into 
__generic_remap_file_range_prep() whose argument list can be modified to 
accepts the iomap_ops pointer.  Then it looks like this:

```
int dax_remap_file_range_prep(struct file *file_in, loff_t pos_in,
				  struct file *file_out, loff_t pos_out,
				  loff_t *len, unsigned int remap_flags,
				  const struct iomap_ops *ops)
{
	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
			pos_out, len, remap_flags, ops);
}
EXPORT_SYMBOL(dax_remap_file_range_prep);

int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
				  struct file *file_out, loff_t pos_out,
				  loff_t *len, unsigned int remap_flags)
{
	return __generic_remap_file_range_prep(file_in, pos_in, file_out,
			pos_out, len, remap_flags, NULL);
}
EXPORT_SYMBOL(generic_remap_file_range_prep);
```

Am i right?


--
Thanks,
Ruan Shiyang.

> 
>> +extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
>> +					 struct inode *dest, loff_t destoff,
>> +					 loff_t len, bool *is_same);
> 
> no need for the extern.
> 
> 



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  reply	other threads:[~2021-02-09  9:17 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-07 17:09 [Ocfs2-devel] [PATCH 0/7] fsdax, xfs: Add reflink&dedupe support for fsdax Shiyang Ruan
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 1/7] fsdax: Output address in dax_iomap_pfn() and rename it Shiyang Ruan
2021-02-08 15:11   ` Christoph Hellwig
2021-02-22  7:44   ` Xiaoguang Wang
2021-02-23  1:32     ` [Ocfs2-devel] 回复: " ruansy.fnst
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 2/7] fsdax: Introduce dax_copy_edges() for CoW Shiyang Ruan
2021-02-08 15:11   ` Christoph Hellwig
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 3/7] fsdax: Copy data before write Shiyang Ruan
2021-02-08 15:14   ` Christoph Hellwig
2021-02-09  1:53     ` Ruan Shiyang
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 4/7] fsdax: Replace mmap entry in case of CoW Shiyang Ruan
2021-02-08 15:16   ` Christoph Hellwig
2021-02-16 13:11   ` David Sterba
2021-02-17  3:06     ` Ruan Shiyang
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 5/7] fsdax: Dedup file range to use a compare function Shiyang Ruan
2021-02-08 15:19   ` Christoph Hellwig
2021-02-09  9:15     ` Ruan Shiyang [this message]
2021-02-09  9:34       ` Christoph Hellwig
2021-02-09  9:46         ` Ruan Shiyang
2021-02-10 13:19           ` Christoph Hellwig
2021-02-17  3:24             ` Ruan Shiyang
2021-02-18 16:20               ` Darrick J. Wong
2021-02-25  7:35                 ` Christoph Hellwig
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 6/7] fs/xfs: Handle CoW for fsdax write() path Shiyang Ruan
2021-02-08 15:24   ` Christoph Hellwig
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 7/7] fs/xfs: Add dedupe support for fsdax Shiyang Ruan
2021-02-08 15:39 ` [Ocfs2-devel] [PATCH 0/7] fsdax, xfs: Add reflink&dedupe " Jan Kara
2021-02-09  1:50   ` Ruan Shiyang

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