Re: [PATCH 10/10] xfs: punch delalloc extents from the COW fork for COW writes

Darrick J. Wong
2024-08-27T16:44:41Z

On Tue, Aug 27, 2024 at 07:09:57AM +0200, Christoph Hellwig wrote:
> When ->iomap_end is called on a short write to the COW fork it needs to
> punch stale delalloc data from the COW fork and not the data fork.
>
> Ensure that IOMAP_F_NEW is set for new COW fork allocations in
> xfs_buffered_write_iomap_begin, and then use the IOMAP_F_SHARED flag
> in xfs_buffered_write_delalloc_punch to decide which fork to punch.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks fine,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
> fs/xfs/xfs_iomap.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 22e9613a995f12..4113e09cb836a8 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1195,7 +1195,7 @@ xfs_buffered_write_iomap_begin(
> xfs_trim_extent(&cmap, offset_fsb, imap.br_startoff - offset_fsb);
> }
>
> - iomap_flags = IOMAP_F_SHARED;
> + iomap_flags |= IOMAP_F_SHARED;
> seq = xfs_iomap_inode_sequence(ip, iomap_flags);
> xfs_iunlock(ip, lockmode);
> return xfs_bmbt_to_iomap(ip, iomap, &cmap, flags, iomap_flags, seq);
> @@ -1212,8 +1212,10 @@ xfs_buffered_write_delalloc_punch(
> loff_t length,
> struct iomap *iomap)
> {
> - xfs_bmap_punch_delalloc_range(XFS_I(inode), XFS_DATA_FORK, offset,
> - offset + length);
> + xfs_bmap_punch_delalloc_range(XFS_I(inode),
> + (iomap->flags & IOMAP_F_SHARED) ?
> + XFS_COW_FORK : XFS_DATA_FORK,
> + offset, offset + length);
> }
>
> static int
> --
> 2.43.0
>
>