Re: [PATCH v8 13/20] xfs: Add helpers xfs_attr_is_shortform and xfs_attr_set_shortform

From: Allison Collins <allison.henderson@oracle.com>
To: Brian Foster <bfoster@redhat.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH v8 13/20] xfs: Add helpers xfs_attr_is_shortform and xfs_attr_set_shortform
Date: Tue, 7 Apr 2020 14:53:26 -0700	[thread overview]
Message-ID: <00b93566-bb7d-544d-698a-c239e7c5f7b3@oracle.com> (raw)
In-Reply-To: <20200407152301.GE28936@bfoster>


On 4/7/20 8:23 AM, Brian Foster wrote:
> On Fri, Apr 03, 2020 at 03:12:22PM -0700, Allison Collins wrote:
>> In this patch, we hoist code from xfs_attr_set_args into two new helpers
>> xfs_attr_is_shortform and xfs_attr_set_shortform.  These two will help
>> to simplify xfs_attr_set_args when we get into delayed attrs later.
>>
>> Signed-off-by: Allison Collins <allison.henderson@oracle.com>
>> ---
>>   fs/xfs/libxfs/xfs_attr.c | 107 +++++++++++++++++++++++++++++++----------------
>>   1 file changed, 72 insertions(+), 35 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>> index 4225a94..ba26ffe 100644
>> --- a/fs/xfs/libxfs/xfs_attr.c
>> +++ b/fs/xfs/libxfs/xfs_attr.c
>> @@ -204,6 +204,66 @@ xfs_attr_try_sf_addname(
>>   }
>>   
>>   /*
>> + * Check to see if the attr should be upgraded from non-existent or shortform to
>> + * single-leaf-block attribute list.
>> + */
>> +static inline bool
>> +xfs_attr_is_shortform(
>> +	struct xfs_inode    *ip)
>> +{
>> +	return ip->i_d.di_aformat == XFS_DINODE_FMT_LOCAL ||
>> +	      (ip->i_d.di_aformat == XFS_DINODE_FMT_EXTENTS &&
>> +	      ip->i_d.di_anextents == 0);
> 
> Logic should be indented similar to the original:
> 
> 	return ip->i_d.di_aformat == XFS_DINODE_FMT_LOCAL ||
> 	       (ip->i_d.di_aformat == XFS_DINODE_FMT_EXTENTS &&
> 		ip->i_d.di_anextents == 0);
> 
> Otherwise looks good:
> 
> Reviewed-by: Brian Foster <bfoster@redhat.com>
Alrighty, will fix.  Thanks!

Allison

> 
>> +}
>> +
>> +/*
>> + * Attempts to set an attr in shortform, or converts the tree to leaf form if
>> + * there is not enough room.  If the attr is set, the transaction is committed
>> + * and set to NULL.
>> + */
>> +STATIC int
>> +xfs_attr_set_shortform(
>> +	struct xfs_da_args	*args,
>> +	struct xfs_buf		**leaf_bp)
>> +{
>> +	struct xfs_inode	*dp = args->dp;
>> +	int			error, error2 = 0;
>> +
>> +	/*
>> +	 * Try to add the attr to the attribute list in the inode.
>> +	 */
>> +	error = xfs_attr_try_sf_addname(dp, args);
>> +	if (error != -ENOSPC) {
>> +		error2 = xfs_trans_commit(args->trans);
>> +		args->trans = NULL;
>> +		return error ? error : error2;
>> +	}
>> +	/*
>> +	 * It won't fit in the shortform, transform to a leaf block.  GROT:
>> +	 * another possible req'mt for a double-split btree op.
>> +	 */
>> +	error = xfs_attr_shortform_to_leaf(args, leaf_bp);
>> +	if (error)
>> +		return error;
>> +
>> +	/*
>> +	 * Prevent the leaf buffer from being unlocked so that a concurrent AIL
>> +	 * push cannot grab the half-baked leaf buffer and run into problems
>> +	 * with the write verifier. Once we're done rolling the transaction we
>> +	 * can release the hold and add the attr to the leaf.
>> +	 */
>> +	xfs_trans_bhold(args->trans, *leaf_bp);
>> +	error = xfs_defer_finish(&args->trans);
>> +	xfs_trans_bhold_release(args->trans, *leaf_bp);
>> +	if (error) {
>> +		xfs_trans_brelse(args->trans, *leaf_bp);
>> +		return error;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>>    * Set the attribute specified in @args.
>>    */
>>   int
>> @@ -212,48 +272,25 @@ xfs_attr_set_args(
>>   {
>>   	struct xfs_inode	*dp = args->dp;
>>   	struct xfs_buf          *leaf_bp = NULL;
>> -	int			error, error2 = 0;
>> +	int			error = 0;
>>   
>>   	/*
>> -	 * If the attribute list is non-existent or a shortform list,
>> -	 * upgrade it to a single-leaf-block attribute list.
>> +	 * If the attribute list is already in leaf format, jump straight to
>> +	 * leaf handling.  Otherwise, try to add the attribute to the shortform
>> +	 * list; if there's no room then convert the list to leaf format and try
>> +	 * again.
>>   	 */
>> -	if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL ||
>> -	    (dp->i_d.di_aformat == XFS_DINODE_FMT_EXTENTS &&
>> -	     dp->i_d.di_anextents == 0)) {
>> -
>> -		/*
>> -		 * Try to add the attr to the attribute list in the inode.
>> -		 */
>> -		error = xfs_attr_try_sf_addname(dp, args);
>> -		if (error != -ENOSPC) {
>> -			error2 = xfs_trans_commit(args->trans);
>> -			args->trans = NULL;
>> -			return error ? error : error2;
>> -		}
>> -
>> -		/*
>> -		 * It won't fit in the shortform, transform to a leaf block.
>> -		 * GROT: another possible req'mt for a double-split btree op.
>> -		 */
>> -		error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
>> -		if (error)
>> -			return error;
>> +	if (xfs_attr_is_shortform(dp)) {
>>   
>>   		/*
>> -		 * Prevent the leaf buffer from being unlocked so that a
>> -		 * concurrent AIL push cannot grab the half-baked leaf
>> -		 * buffer and run into problems with the write verifier.
>> -		 * Once we're done rolling the transaction we can release
>> -		 * the hold and add the attr to the leaf.
>> +		 * If the attr was successfully set in shortform, the
>> +		 * transaction is committed and set to NULL.  Otherwise, is it
>> +		 * converted from shortform to leaf, and the transaction is
>> +		 * retained.
>>   		 */
>> -		xfs_trans_bhold(args->trans, leaf_bp);
>> -		error = xfs_defer_finish(&args->trans);
>> -		xfs_trans_bhold_release(args->trans, leaf_bp);
>> -		if (error) {
>> -			xfs_trans_brelse(args->trans, leaf_bp);
>> +		error = xfs_attr_set_shortform(args, &leaf_bp);
>> +		if (error || !args->trans)
>>   			return error;
>> -		}
>>   	}
>>   
>>   	if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
>> -- 
>> 2.7.4
>>
>