linux-kernel - Re: [PATCH] exfat: remove 'rwoffset' in exfat_inode

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Date:   Wed, 16 Sep 2020 14:35:00 +0900
From:   Tetsuhiro Kohada <kohada.t2@...il.com>
To:     Sungjong Seo <sj1557.seo@...sung.com>
Cc:     kohada.tetsuhiro@...mitsubishielectric.co.jp,
        mori.takahiro@...mitsubishielectric.co.jp,
        motai.hirotaka@...mitsubishielectric.co.jp,
        'Namjae Jeon' <namjae.jeon@...sung.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] exfat: remove 'rwoffset' in exfat_inode_info



On 2020/09/12 14:01, Sungjong Seo wrote:
>> Remove 'rwoffset' in exfat_inode_info and replace it with the
>> parameter(cpos) of exfat_readdir.
>> Since rwoffset of  is referenced only by exfat_readdir, it is not
>> necessary a exfat_inode_info's member.
>>
>> Signed-off-by: Tetsuhiro Kohada <kohada.t2@...il.com>
>> ---
>>   fs/exfat/dir.c      | 16 ++++++----------
>>   fs/exfat/exfat_fs.h |  2 --
>>   fs/exfat/file.c     |  2 --
>>   fs/exfat/inode.c    |  3 ---
>>   fs/exfat/super.c    |  1 -
>>   5 files changed, 6 insertions(+), 18 deletions(-)
>>
>> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c index
>> a9b13ae3f325..fa5bb72aa295 100644
>> --- a/fs/exfat/dir.c
>> +++ b/fs/exfat/dir.c
> [snip]
>> sector @@ -262,13 +260,11 @@ static int exfat_iterate(struct file *filp,
>> struct dir_context *ctx)
>>   		goto end_of_dir;
>>   	}
>>
>> -	cpos = EXFAT_DEN_TO_B(ei->rwoffset);
>> -
>>   	if (!nb->lfn[0])
>>   		goto end_of_dir;
>>
>>   	i_pos = ((loff_t)ei->start_clu << 32) |
>> -		((ei->rwoffset - 1) & 0xffffffff);
>> +		(EXFAT_B_TO_DEN(cpos-1) & 0xffffffff);
> 
> Need to fix the above line to be:
> (EXFAT_B_TO_DEN(cpos)-1)) & 0xffffffff);


Here, we simply converted so that the calculation results would be the same.
But after reading it carefully again, I noticed.
  - Why use the previous entry?
  - Why does cpos point to stream dir-entry in entry-set?

For the former, there is no need to "++dentry" in exfat_readdir().
For the latter, I think cpos should point to the next to current entry-set.

I'll make V2 considering these.
How do you think?

BR
---
Tetsuhiro Kohada <kohada.t2@...il.com>