linux-kernel - Re: [PATCH -next] bcache: Convert to DEFINE_SHOW

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Date:   Fri, 17 Jul 2020 10:22:17 +0800
From:   Coly Li <colyli@...e.de>
To:     Qinglang Miao <miaoqinglang@...wei.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kent Overstreet <kent.overstreet@...il.com>,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        liuyongqiang13@...wei.com
Subject: Re: [PATCH -next] bcache: Convert to DEFINE_SHOW_ATTRIBUTE

On 2020/7/16 17:54, Coly Li wrote:
> On 2020/7/16 17:03, Qinglang Miao wrote:
>> From: Yongqiang Liu <liuyongqiang13@...wei.com>
>>
> 
> Hi Qianlang and Yongqiang,
> 
>> Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.
>>
>> Signed-off-by: Yongqiang Liu <liuyongqiang13@...wei.com>
>> ---
>>  drivers/md/bcache/closure.c | 16 +++-------------
>>  1 file changed, 3 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/md/bcache/closure.c b/drivers/md/bcache/closure.c
>> index 99222aa5d..37b9c5d49 100644
>> --- a/drivers/md/bcache/closure.c
>> +++ b/drivers/md/bcache/closure.c
>> @@ -159,7 +159,7 @@ void closure_debug_destroy(struct closure *cl)
>>  
>>  static struct dentry *closure_debug;
>>  
>> -static int debug_seq_show(struct seq_file *f, void *data)
>> +static int debug_show(struct seq_file *f, void *data)
>>  {
>>  	struct closure *cl;
>>  
>> @@ -188,17 +188,7 @@ static int debug_seq_show(struct seq_file *f, void *data)
>>  	return 0;
>>  }
>>  
>> -static int debug_seq_open(struct inode *inode, struct file *file)
>> -{
>> -	return single_open(file, debug_seq_show, NULL);
>> -}
>> -
> 
> Here NULL is sent to single_open(), in DEFINE_SHOW_ATTRIBUTE()
> inode->i_private is sent into single_open(). I don't see the commit log
> mentions or estimates such change.
> 

Still this change modifies original code logic, I need to know the exact
effect before taking this patch.

> 
>> -static const struct file_operations debug_ops = {
>> -	.owner		= THIS_MODULE,
>> -	.open		= debug_seq_open,
>> -	.read_iter		= seq_read_iter,
> 
> I doubt this patch applies to Linux v5.8-rc, this is how debug_ops is
> defined in Linux v5.8-rc5,
>

I realize your patch is against linux-next, which is ahead of both
linux-block and mainline tree. So this patch does not apply to
linux-block tree, which is my upstream for bcache going to upstream.

I suggest to generate the patch against latest mainline kernel, or
linux-block branch for next merge window (for 5.9 it is branch
remotes/origin/for-5.9/drivers).


> 196 static const struct file_operations debug_ops = {
> 197         .owner          = THIS_MODULE,
> 198         .open           = debug_seq_open,
> 199         .read           = seq_read,
> 200         .release        = single_release
> 201 };
> 
>> -	.release	= single_release
>> -};
>> +DEFINE_SHOW_ATTRIBUTE(debug);
>>  
>>  void  __init closure_debug_init(void)
>>  {
>> @@ -209,7 +199,7 @@ void  __init closure_debug_init(void)
>>  		 * about this.
>>  		 */
>>  		closure_debug = debugfs_create_file(
>> -			"closures", 0400, bcache_debug, NULL, &debug_ops);
>> +				"closures", 0400, bcache_debug, NULL, &debug_fops);
>>  }
>>  #endif
> 
> Do you test your change with upstream kernel ? Or at least you should
> try to apply and compile the patch with latest upstream kernel.

I withdraw the above wrong word, the -next tag in patch subject was
overlooked by me. Next time I will try to avoid such mistake.

Coly Li