Re: [PATCH 6/8] xfs: refactor xfs_bmapi_allocate

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

On Fri, Oct 25, 2019 at 05:03:34PM +0200, Christoph Hellwig wrote:
> Avoid duplicate userdata and data fork checks by restructuring the code
> so we only have a helper for userdata allocations that combines these
> checks in a straight foward way.  That also helps to obsoletes the
> comments explaining what the code does as it is now clearly obvious.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

LGTM,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/xfs/libxfs/xfs_bmap.c | 93 +++++++++++++++++++---------------------
>  1 file changed, 45 insertions(+), 48 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index ef75e223cb70..c278eff29e82 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -3641,20 +3641,6 @@ xfs_bmap_btalloc(
>  	return 0;
>  }
>  
> -/*
> - * xfs_bmap_alloc is called by xfs_bmapi to allocate an extent for a file.
> - * It figures out where to ask the underlying allocator to put the new extent.
> - */
> -STATIC int
> -xfs_bmap_alloc(
> -	struct xfs_bmalloca	*ap)	/* bmap alloc argument struct */
> -{
> -	if (XFS_IS_REALTIME_INODE(ap->ip) &&
> -	    xfs_alloc_is_userdata(ap->datatype))
> -		return xfs_bmap_rtalloc(ap);
> -	return xfs_bmap_btalloc(ap);
> -}
> -
>  /* Trim extent to fit a logical block range. */
>  void
>  xfs_trim_extent(
> @@ -4010,6 +3996,42 @@ xfs_bmapi_reserve_delalloc(
>  	return error;
>  }
>  
> +static int
> +xfs_bmap_alloc_userdata(
> +	struct xfs_bmalloca	*bma)
> +{
> +	struct xfs_mount	*mp = bma->ip->i_mount;
> +	int			whichfork = xfs_bmapi_whichfork(bma->flags);
> +	int			error;
> +
> +	/*
> +	 * Set the data type being allocated. For the data fork, the first data
> +	 * in the file is treated differently to all other allocations. For the
> +	 * attribute fork, we only need to ensure the allocated range is not on
> +	 * the busy list.
> +	 */
> +	bma->datatype = XFS_ALLOC_NOBUSY;
> +	if (bma->flags & XFS_BMAPI_ZERO)
> +		bma->datatype |= XFS_ALLOC_USERDATA_ZERO;
> +	if (whichfork == XFS_DATA_FORK) {
> +		if (bma->offset == 0)
> +			bma->datatype |= XFS_ALLOC_INITIAL_USER_DATA;
> +		else
> +			bma->datatype |= XFS_ALLOC_USERDATA;
> +
> +		if (mp->m_dalign && bma->length >= mp->m_dalign) {
> +			error = xfs_bmap_isaeof(bma, whichfork);
> +			if (error)
> +				return error;
> +		}
> +
> +		if (XFS_IS_REALTIME_INODE(bma->ip))
> +			return xfs_bmap_rtalloc(bma);
> +	}
> +
> +	return xfs_bmap_btalloc(bma);
> +}
> +
>  static int
>  xfs_bmapi_allocate(
>  	struct xfs_bmalloca	*bma)
> @@ -4037,43 +4059,18 @@ xfs_bmapi_allocate(
>  					bma->got.br_startoff - bma->offset);
>  	}
>  
> -	/*
> -	 * Set the data type being allocated. For the data fork, the first data
> -	 * in the file is treated differently to all other allocations. For the
> -	 * attribute fork, we only need to ensure the allocated range is not on
> -	 * the busy list.
> -	 */
> -	if (!(bma->flags & XFS_BMAPI_METADATA)) {
> -		bma->datatype = XFS_ALLOC_NOBUSY;
> -		if (whichfork == XFS_DATA_FORK) {
> -			if (bma->offset == 0)
> -				bma->datatype |= XFS_ALLOC_INITIAL_USER_DATA;
> -			else
> -				bma->datatype |= XFS_ALLOC_USERDATA;
> -		}
> -		if (bma->flags & XFS_BMAPI_ZERO)
> -			bma->datatype |= XFS_ALLOC_USERDATA_ZERO;
> -	}
> -
> -	bma->minlen = (bma->flags & XFS_BMAPI_CONTIG) ? bma->length : 1;
> -
> -	/*
> -	 * Only want to do the alignment at the eof if it is userdata and
> -	 * allocation length is larger than a stripe unit.
> -	 */
> -	if (mp->m_dalign && bma->length >= mp->m_dalign &&
> -	    !(bma->flags & XFS_BMAPI_METADATA) && whichfork == XFS_DATA_FORK) {
> -		error = xfs_bmap_isaeof(bma, whichfork);
> -		if (error)
> -			return error;
> -	}
> +	if (bma->flags & XFS_BMAPI_CONTIG)
> +		bma->minlen = bma->length;
> +	else
> +		bma->minlen = 1;
>  
> -	error = xfs_bmap_alloc(bma);
> -	if (error)
> +	if (bma->flags & XFS_BMAPI_METADATA)
> +		error = xfs_bmap_btalloc(bma);
> +	else
> +		error = xfs_bmap_alloc_userdata(bma);
> +	if (error || bma->blkno == NULLFSBLOCK)
>  		return error;
>  
> -	if (bma->blkno == NULLFSBLOCK)
> -		return 0;
>  	if ((ifp->if_flags & XFS_IFBROOT) && !bma->cur)
>  		bma->cur = xfs_bmbt_init_cursor(mp, bma->tp, bma->ip, whichfork);
>  	/*
> -- 
> 2.20.1
>