Re: [PATCH 4/7] xfs: always trim mapping to requested range for zero range

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

On Thu, Jun 05, 2025 at 01:33:54PM -0400, Brian Foster wrote:
> Refactor and tweak the IOMAP_ZERO logic in preparation to support
> filling the folio batch for unwritten mappings. Drop the superfluous
> imap offset check since the hole case has already been filtered out.
> Split the the delalloc case handling into a sub-branch, and always
> trim the imap to the requested offset/count so it can be more easily
> used to bound the range to lookup in pagecache.
> 
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Yeah, makes sense to me.
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_iomap.c | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index ff05e6b1b0bb..b5cf5bc6308d 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1756,21 +1756,20 @@ xfs_buffered_write_iomap_begin(
>  	}
>  
>  	/*
> -	 * For zeroing, trim a delalloc extent that extends beyond the EOF
> -	 * block.  If it starts beyond the EOF block, convert it to an
> +	 * For zeroing, trim extents that extend beyond the EOF block. If a
> +	 * delalloc extent starts beyond the EOF block, convert it to an
>  	 * unwritten extent.
>  	 */
> -	if ((flags & IOMAP_ZERO) && imap.br_startoff <= offset_fsb &&
> -	    isnullstartblock(imap.br_startblock)) {
> +	if (flags & IOMAP_ZERO) {
>  		xfs_fileoff_t eof_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
>  
> -		if (offset_fsb >= eof_fsb)
> +		if (isnullstartblock(imap.br_startblock) &&
> +		    offset_fsb >= eof_fsb)
>  			goto convert_delay;
> -		if (end_fsb > eof_fsb) {
> +		if (offset_fsb < eof_fsb && end_fsb > eof_fsb)
>  			end_fsb = eof_fsb;
> -			xfs_trim_extent(&imap, offset_fsb,
> -					end_fsb - offset_fsb);
> -		}
> +
> +		xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
>  	}
>  
>  	/*
> -- 
> 2.49.0
> 
>