linux-kernel - Re: [PATCH] xfs_bmap

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Date:   Mon, 9 Jul 2018 11:42:54 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     "Darrick J. Wong" <darrick.wong@...cle.com>
Cc:     linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xfs_bmap_util: use swap macro

Hi Darrick,

On 07/09/2018 11:39 AM, Darrick J. Wong wrote:
> On Mon, Jul 09, 2018 at 09:05:39AM -0500, Gustavo A. R. Silva wrote:
>> Make use of the swap macro and remove some unnecessary variables.
>> This makes the code easier to read and maintain. Also, reduces the
>> stack usage.
>>
>> This code was detected with the help of Coccinelle.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
>> ---
>>  fs/xfs/xfs_bmap_util.c | 13 ++-----------
>>  1 file changed, 2 insertions(+), 11 deletions(-)
>>
>> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
>> index 83b1e8c..4b0b16f 100644
>> --- a/fs/xfs/xfs_bmap_util.c
>> +++ b/fs/xfs/xfs_bmap_util.c
>> @@ -1691,7 +1691,6 @@ xfs_swap_extent_forks(
>>  	int			*src_log_flags,
>>  	int			*target_log_flags)
>>  {
>> -	struct xfs_ifork	tempifp, *ifp, *tifp;
>>  	xfs_filblks_t		aforkblks = 0;
>>  	xfs_filblks_t		taforkblks = 0;
>>  	xfs_extnum_t		junk;
>> @@ -1733,11 +1732,7 @@ xfs_swap_extent_forks(
>>  	/*
>>  	 * Swap the data forks of the inodes
>>  	 */
>> -	ifp = &ip->i_df;
>> -	tifp = &tip->i_df;
>> -	tempifp = *ifp;		/* struct copy */
>> -	*ifp = *tifp;		/* struct copy */
>> -	*tifp = tempifp;	/* struct copy */
>> +	swap(ip->i_df, tip->i_df);
>>  
>>  	/*
>>  	 * Fix the on-disk inode values
> 
> Why not use swap() on the di_nextents and di_format exchange below here
> too?
> 
>> @@ -1987,14 +1982,10 @@ xfs_swap_extents(
>>  
>>  	/* Swap the cow forks. */
>>  	if (xfs_sb_version_hasreflink(&mp->m_sb)) {
>> -		xfs_extnum_t	extnum;
>> -
>>  		ASSERT(ip->i_cformat == XFS_DINODE_FMT_EXTENTS);
>>  		ASSERT(tip->i_cformat == XFS_DINODE_FMT_EXTENTS);
>>  
>> -		extnum = ip->i_cnextents;
>> -		ip->i_cnextents = tip->i_cnextents;
>> -		tip->i_cnextents = extnum;
>> +		swap(ip->i_cnextents, tip->i_cnextents);
>>  
>>  		cowfp = ip->i_cowfp;
>>  		ip->i_cowfp = tip->i_cowfp;
> 
> Same here -- why not use swap on {ip,tip}->i_cowfp?
> 

Yep. I'll send a new patch shortly.

Thanks for the feedback.
--
Gustavo