Re: [PATCH v15 05/22] xfs: Add helper xfs_attr_set_fmt

[Brian Foster <bfoster@redhat.com>]

On Thu, Feb 18, 2021 at 09:53:31AM -0700, Allison Henderson wrote:
> This patch adds a helper function xfs_attr_set_fmt.  This will help
> isolate the code that will require state management from the portions
> that do not.  xfs_attr_set_fmt returns 0 when the attr has been set and
> no further action is needed.  It returns -EAGAIN when shortform has been
> transformed to leaf, and the calling function should proceed the set the
> attr in leaf form.
> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/libxfs/xfs_attr.c | 77 +++++++++++++++++++++++++++---------------------
>  1 file changed, 44 insertions(+), 33 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index a064c5b..205ad26 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -216,6 +216,46 @@ xfs_attr_is_shortform(
>  		ip->i_afp->if_nextents == 0);
>  }
>  
> +STATIC int
> +xfs_attr_set_fmt(
> +	struct xfs_da_args	*args)
> +{
> +	struct xfs_buf          *leaf_bp = NULL;
> +	struct xfs_inode	*dp = args->dp;
> +	int			error2, error = 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.
> +	 */
> +	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 -EAGAIN;
> +}
> +
>  /*
>   * Set the attribute specified in @args.
>   */
> @@ -224,8 +264,7 @@ xfs_attr_set_args(
>  	struct xfs_da_args	*args)
>  {
>  	struct xfs_inode	*dp = args->dp;
> -	struct xfs_buf          *leaf_bp = NULL;
> -	int			error2, error = 0;
> +	int			error;
>  
>  	/*
>  	 * If the attribute list is already in leaf format, jump straight to
> @@ -234,36 +273,9 @@ xfs_attr_set_args(
>  	 * again.
>  	 */
>  	if (xfs_attr_is_shortform(dp)) {
> -		/*
> -		 * 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)
> +		error = xfs_attr_set_fmt(args);
> +		if (error != -EAGAIN)
>  			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.
> -		 */
> -		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;
> -		}
>  	}
>  
>  	if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
> @@ -297,8 +309,7 @@ xfs_attr_set_args(
>  			return error;
>  	}
>  
> -	error = xfs_attr_node_addname(args);
> -	return error;
> +	return xfs_attr_node_addname(args);
>  }
>  
>  /*
> -- 
> 2.7.4
>