Re: [PATCH] xfs: remove xfs_attr_leaf_hasname

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Jan 09, 2026 at 04:17:40PM +0100, Christoph Hellwig wrote:
> The calling convention of xfs_attr_leaf_hasname() is problematic, because
> it returns a NULL buffer when xfs_attr3_leaf_read fails, a valid buffer
> when xfs_attr3_leaf_lookup_int returns -ENOATTR or -EEXIST, and a
> non-NULL buffer pointer for an already released buffer when
> xfs_attr3_leaf_lookup_int fails with other error values.
> 
> Fix this by simply open coding xfs_attr_leaf_hasname in the callers, so
> that the buffer release code is done by each caller of
> xfs_attr3_leaf_read.
> 
> X-Cc: stable@vger.kernel.org # v5.19+
> Fixes: 07120f1abdff ("xfs: Add xfs_has_attr and subroutines")
> Reported-by: Mark Tinguely <mark.tinguely@oracle.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Blerrgh, xfs_attr3_leaf_lookup_int encoding results with error numbers
makes my brain hurt every time I look at the xattr code... but this
patch is (afaict) a correct way to avoid the **bp state confusion
presented by xfs_attr_leaf_hasname.

Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/xfs/libxfs/xfs_attr.c | 75 +++++++++++++---------------------------
>  1 file changed, 24 insertions(+), 51 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 8c04acd30d48..b88e65c7e45d 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -50,7 +50,6 @@ STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args);
>   */
>  STATIC int xfs_attr_leaf_get(xfs_da_args_t *args);
>  STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
> -STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
>  
>  /*
>   * Internal routines when attribute list is more than one block.
> @@ -979,11 +978,12 @@ xfs_attr_lookup(
>  		return error;
>  
>  	if (xfs_attr_is_leaf(dp)) {
> -		error = xfs_attr_leaf_hasname(args, &bp);
> -
> -		if (bp)
> -			xfs_trans_brelse(args->trans, bp);
> -
> +		error = xfs_attr3_leaf_read(args->trans, args->dp, args->owner,
> +				0, &bp);
> +		if (error)
> +			return error;
> +		error = xfs_attr3_leaf_lookup_int(bp, args);
> +		xfs_trans_brelse(args->trans, bp);
>  		return error;
>  	}
>  
> @@ -1222,27 +1222,6 @@ xfs_attr_shortform_addname(
>   * External routines when attribute list is one block
>   *========================================================================*/
>  
> -/*
> - * Return EEXIST if attr is found, or ENOATTR if not
> - */
> -STATIC int
> -xfs_attr_leaf_hasname(
> -	struct xfs_da_args	*args,
> -	struct xfs_buf		**bp)
> -{
> -	int                     error = 0;
> -
> -	error = xfs_attr3_leaf_read(args->trans, args->dp, args->owner, 0, bp);
> -	if (error)
> -		return error;
> -
> -	error = xfs_attr3_leaf_lookup_int(*bp, args);
> -	if (error != -ENOATTR && error != -EEXIST)
> -		xfs_trans_brelse(args->trans, *bp);
> -
> -	return error;
> -}
> -
>  /*
>   * Remove a name from the leaf attribute list structure
>   *
> @@ -1253,25 +1232,22 @@ STATIC int
>  xfs_attr_leaf_removename(
>  	struct xfs_da_args	*args)
>  {
> -	struct xfs_inode	*dp;
> -	struct xfs_buf		*bp;
> +	struct xfs_inode	*dp = args->dp;
>  	int			error, forkoff;
> +	struct xfs_buf		*bp;
>  
>  	trace_xfs_attr_leaf_removename(args);
>  
> -	/*
> -	 * Remove the attribute.
> -	 */
> -	dp = args->dp;
> -
> -	error = xfs_attr_leaf_hasname(args, &bp);
> -	if (error == -ENOATTR) {
> +	error = xfs_attr3_leaf_read(args->trans, args->dp, args->owner, 0, &bp);
> +	if (error)
> +		return error;
> +	error = xfs_attr3_leaf_lookup_int(bp, args);
> +	if (error != -EEXIST) {
>  		xfs_trans_brelse(args->trans, bp);
> -		if (args->op_flags & XFS_DA_OP_RECOVERY)
> +		if (error == -ENOATTR && (args->op_flags & XFS_DA_OP_RECOVERY))
>  			return 0;
>  		return error;
> -	} else if (error != -EEXIST)
> -		return error;
> +	}
>  
>  	xfs_attr3_leaf_remove(bp, args);
>  
> @@ -1295,23 +1271,20 @@ xfs_attr_leaf_removename(
>   * Returns 0 on successful retrieval, otherwise an error.
>   */
>  STATIC int
> -xfs_attr_leaf_get(xfs_da_args_t *args)
> +xfs_attr_leaf_get(
> +	struct xfs_da_args	*args)
>  {
> -	struct xfs_buf *bp;
> -	int error;
> +	struct xfs_buf		*bp;
> +	int			error;
>  
>  	trace_xfs_attr_leaf_get(args);
>  
> -	error = xfs_attr_leaf_hasname(args, &bp);
> -
> -	if (error == -ENOATTR)  {
> -		xfs_trans_brelse(args->trans, bp);
> -		return error;
> -	} else if (error != -EEXIST)
> +	error = xfs_attr3_leaf_read(args->trans, args->dp, args->owner, 0, &bp);
> +	if (error)
>  		return error;
> -
> -
> -	error = xfs_attr3_leaf_getvalue(bp, args);
> +	error = xfs_attr3_leaf_lookup_int(bp, args);
> +	if (error == -EEXIST)
> +		error = xfs_attr3_leaf_getvalue(bp, args);
>  	xfs_trans_brelse(args->trans, bp);
>  	return error;
>  }
> -- 
> 2.47.3
> 
>