linux-kernel - Re: [PATCH 10/20] ext4: get rid of ppath in ext4_ext_create_new

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Message-ID: <44337bbe-bb24-444d-a5b8-f579eceaeac5@huaweicloud.com>
Date: Sat, 27 Jul 2024 14:35:18 +0800
From: Baokun Li <libaokun@...weicloud.com>
To: Jan Kara <jack@...e.cz>
Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca,
 ritesh.list@...il.com, linux-kernel@...r.kernel.org, yi.zhang@...wei.com,
 yangerkun@...wei.com, Baokun Li <libaokun1@...wei.com>,
 Baokun Li <libaokun@...weicloud.com>
Subject: Re: [PATCH 10/20] ext4: get rid of ppath in
 ext4_ext_create_new_leaf()

On 2024/7/25 18:46, Jan Kara wrote:
> On Wed 10-07-24 12:06:44, libaokun@...weicloud.com wrote:
>> From: Baokun Li <libaokun1@...wei.com>
>>
>> The use of path and ppath is now very confusing, so to make the code more
>> readable, pass path between functions uniformly, and get rid of ppath.
>>
>> To get rid of the ppath in ext4_ext_create_new_leaf(), the following is
>> done here:
>>
>>   * Free the extents path when an error is encountered.
>>   * Its caller needs to update ppath if it uses ppath.
>>
>> No functional changes.
>>
>> Signed-off-by: Baokun Li <libaokun1@...wei.com>
> Just one nit below. Otherwise feel free to add:
>
> Reviewed-by: Jan Kara <jack@...e.cz>
>
>> @@ -1424,28 +1423,24 @@ static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
>>   		 * entry: create all needed subtree and add new leaf */
>>   		err = ext4_ext_split(handle, inode, mb_flags, path, newext, i);
>>   		if (err)
>> -			goto out;
>> +			goto errout;
>>   
>>   		/* refill path */
>>   		path = ext4_find_extent(inode,
>>   				    (ext4_lblk_t)le32_to_cpu(newext->ee_block),
>>   				    path, gb_flags);
>> -		if (IS_ERR(path))
>> -			err = PTR_ERR(path);
> So I'd rather have here:
> 		return path;
>
> That way it's obvious we will not confuse some code below with error stored
> in 'path' and we can also save one indentation level by removing 'else'
> below (probably do reindenting in a separate patch).
>
> 								Honza
Yes, that looks clearer! I'll add 'return path' in the next version, and
add a cleanup patch after this one to save indentation.

Thanks,
Baokun
>>   	} else {
>>   		/* tree is full, time to grow in depth */
>>   		err = ext4_ext_grow_indepth(handle, inode, mb_flags);
>>   		if (err)
>> -			goto out;
>> +			goto errout;
>>   
>>   		/* refill path */
>>   		path = ext4_find_extent(inode,
>>   				   (ext4_lblk_t)le32_to_cpu(newext->ee_block),
>>   				    path, gb_flags);
>> -		if (IS_ERR(path)) {
>> -			err = PTR_ERR(path);
>> -			goto out;
>> -		}
>> +		if (IS_ERR(path))
>> +			return path;
>>   
>>   		/*
>>   		 * only first (depth 0 -> 1) produces free space;
>> @@ -1457,9 +1452,11 @@ static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
>>   			goto repeat;
>>   		}
>>   	}
>> -out:
>> -	*ppath = IS_ERR(path) ? NULL : path;
>> -	return err;
>> +	return path;
>> +
>> +errout:
>> +	ext4_free_ext_path(path);
>> +	return ERR_PTR(err);
>>   }
>>   
>>   /*
>> @@ -2112,10 +2109,14 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
>>   	 */
>>   	if (gb_flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
>>   		mb_flags |= EXT4_MB_USE_RESERVED;
>> -	err = ext4_ext_create_new_leaf(handle, inode, mb_flags, gb_flags,
>> -				       ppath, newext);
>> -	if (err)
>> +	path = ext4_ext_create_new_leaf(handle, inode, mb_flags, gb_flags,
>> +					path, newext);
>> +	if (IS_ERR(path)) {
>> +		*ppath = NULL;
>> +		err = PTR_ERR(path);
>>   		goto cleanup;
>> +	}
>> +	*ppath = path;
>>   	depth = ext_depth(inode);
>>   	eh = path[depth].p_hdr;
>>   
>> -- 
>> 2.39.2
>>
-- 
With Best Regards,
Baokun Li