Re: [PATCH v9 05/24] xfs: Split apart xfs_attr_leaf_addname

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Thu, Apr 30, 2020 at 03:49:57PM -0700, Allison Collins wrote:
> Split out new helper function xfs_attr_leaf_try_add from
> xfs_attr_leaf_addname. Because new delayed attribute routines cannot
> roll transactions, we split off the parts of xfs_attr_leaf_addname that
> we can use, and move the commit into the calling function.
> 
> Signed-off-by: Allison Collins <allison.henderson@oracle.com>
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Chandan Rajendra <chandanrlinux@gmail.com>

<groan> I just replied to the xfsprogs version of this patch by accident. :(

Modulo the comments I made in that reply, the rest of the patch looks
ok.

--D

> ---
>  fs/xfs/libxfs/xfs_attr.c | 94 ++++++++++++++++++++++++++++++------------------
>  1 file changed, 60 insertions(+), 34 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index dcbc475..b3b21a7 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -256,10 +256,30 @@ xfs_attr_set_args(
>  		}
>  	}
>  
> -	if (xfs_bmap_one_block(dp, XFS_ATTR_FORK))
> +	if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
>  		error = xfs_attr_leaf_addname(args);
> -	else
> -		error = xfs_attr_node_addname(args);
> +		if (error != -ENOSPC)
> +			return error;
> +
> +		/*
> +		 * Commit that transaction so that the node_addname()
> +		 * call can manage its own transactions.
> +		 */
> +		error = xfs_defer_finish(&args->trans);
> +		if (error)
> +			return error;
> +
> +		/*
> +		 * Commit the current trans (including the inode) and
> +		 * start a new one.
> +		 */
> +		error = xfs_trans_roll_inode(&args->trans, dp);
> +		if (error)
> +			return error;
> +
> +	}
> +
> +	error = xfs_attr_node_addname(args);
>  	return error;
>  }
>  
> @@ -507,20 +527,21 @@ xfs_attr_shortform_addname(xfs_da_args_t *args)
>   *========================================================================*/
>  
>  /*
> - * Add a name to the leaf attribute list structure
> + * Tries to add an attribute to an inode in leaf form
>   *
> - * This leaf block cannot have a "remote" value, we only call this routine
> - * if bmap_one_block() says there is only one block (ie: no remote blks).
> + * This function is meant to execute as part of a delayed operation and leaves
> + * the transaction handling to the caller.  On success the attribute is added
> + * and the inode and transaction are left dirty.  If there is not enough space,
> + * the attr data is converted to node format and -ENOSPC is returned. Caller is
> + * responsible for handling the dirty inode and transaction or adding the attr
> + * in node format.
>   */
>  STATIC int
> -xfs_attr_leaf_addname(
> -	struct xfs_da_args	*args)
> +xfs_attr_leaf_try_add(
> +	struct xfs_da_args	*args,
> +	struct xfs_buf		*bp)
>  {
> -	struct xfs_buf		*bp;
> -	int			retval, error, forkoff;
> -	struct xfs_inode	*dp = args->dp;
> -
> -	trace_xfs_attr_leaf_addname(args);
> +	int			retval, error;
>  
>  	/*
>  	 * Look up the given attribute in the leaf block.  Figure out if
> @@ -562,31 +583,39 @@ xfs_attr_leaf_addname(
>  	retval = xfs_attr3_leaf_add(bp, args);
>  	if (retval == -ENOSPC) {
>  		/*
> -		 * Promote the attribute list to the Btree format, then
> -		 * Commit that transaction so that the node_addname() call
> -		 * can manage its own transactions.
> +		 * Promote the attribute list to the Btree format. Unless an
> +		 * error occurs, retain the -ENOSPC retval
>  		 */
>  		error = xfs_attr3_leaf_to_node(args);
>  		if (error)
>  			return error;
> -		error = xfs_defer_finish(&args->trans);
> -		if (error)
> -			return error;
> +	}
> +	return retval;
> +out_brelse:
> +	xfs_trans_brelse(args->trans, bp);
> +	return retval;
> +}
>  
> -		/*
> -		 * Commit the current trans (including the inode) and start
> -		 * a new one.
> -		 */
> -		error = xfs_trans_roll_inode(&args->trans, dp);
> -		if (error)
> -			return error;
>  
> -		/*
> -		 * Fob the whole rest of the problem off on the Btree code.
> -		 */
> -		error = xfs_attr_node_addname(args);
> +/*
> + * Add a name to the leaf attribute list structure
> + *
> + * This leaf block cannot have a "remote" value, we only call this routine
> + * if bmap_one_block() says there is only one block (ie: no remote blks).
> + */
> +STATIC int
> +xfs_attr_leaf_addname(
> +	struct xfs_da_args	*args)
> +{
> +	int			error, forkoff;
> +	struct xfs_buf		*bp = NULL;
> +	struct xfs_inode	*dp = args->dp;
> +
> +	trace_xfs_attr_leaf_addname(args);
> +
> +	error = xfs_attr_leaf_try_add(args, bp);
> +	if (error)
>  		return error;
> -	}
>  
>  	/*
>  	 * Commit the transaction that added the attr name so that
> @@ -681,9 +710,6 @@ xfs_attr_leaf_addname(
>  		error = xfs_attr3_leaf_clearflag(args);
>  	}
>  	return error;
> -out_brelse:
> -	xfs_trans_brelse(args->trans, bp);
> -	return retval;
>  }
>  
>  /*
> -- 
> 2.7.4
>