Re: [PATCH v3 3/3] xfs: check directory data block header padding in scrub

[Darrick J. Wong]

On Sat, Apr 11, 2026 at 03:24:15PM +0100, Yuto Ohnuki wrote:
> Add the missing scrub check for the pad field in directory data block
> headers. Old kernels may have written non-zero padding without issue,
> and the write path now self-heals stale padding on modification. Flag
> non-zero padding as an optimization opportunity (preen) rather than
> corruption.
> 
> Add xchk_fblock_set_preen helper for reporting file fork block issues
> that could be optimized. The trace event xchk_fblock_preen already
> exists.
> 
> Signed-off-by: Yuto Ohnuki <ytohnuki@xxxxxxxxxx>
> ---
>  fs/xfs/scrub/common.c | 11 +++++++++++
>  fs/xfs/scrub/common.h |  2 ++
>  fs/xfs/scrub/dir.c    |  7 ++++++-
>  3 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
> index 20e63069088b..3d40cb0b2496 100644
> --- a/fs/xfs/scrub/common.c
> +++ b/fs/xfs/scrub/common.c
> @@ -251,6 +251,17 @@ xchk_ino_set_preen(
>  	trace_xchk_ino_preen(sc, ino, __return_address);
>  }
>  
> +/* Record a block indexed by a file fork that could be optimized. */
> +void
> +xchk_fblock_set_preen(
> +	struct xfs_scrub        *sc,
> +	int                     whichfork,
> +	xfs_fileoff_t           offset)
> +{
> +	sc->sm->sm_flags |= XFS_SCRUB_OFLAG_PREEN;
> +	trace_xchk_fblock_preen(sc, whichfork, offset, __return_address);
> +}
> +
>  /* Record something being wrong with the filesystem primary superblock. */
>  void
>  xchk_set_corrupt(
> diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
> index f2ecc68538f0..b494d747c008 100644
> --- a/fs/xfs/scrub/common.h
> +++ b/fs/xfs/scrub/common.h
> @@ -25,6 +25,8 @@ bool xchk_fblock_xref_process_error(struct xfs_scrub *sc,
>  void xchk_block_set_preen(struct xfs_scrub *sc,
>  		struct xfs_buf *bp);
>  void xchk_ino_set_preen(struct xfs_scrub *sc, xfs_ino_t ino);
> +void xchk_fblock_set_preen(struct xfs_scrub *sc,
> +		int whichfork, xfs_fileoff_t offset);
>  
>  void xchk_set_corrupt(struct xfs_scrub *sc);
>  void xchk_block_set_corrupt(struct xfs_scrub *sc,
> diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c
> index e09724cd3725..09715a4aa154 100644
> --- a/fs/xfs/scrub/dir.c
> +++ b/fs/xfs/scrub/dir.c
> @@ -492,7 +492,12 @@ xchk_directory_data_bestfree(
>  		goto out;
>  	xchk_buffer_recheck(sc, bp);
>  
> -	/* XXX: Check xfs_dir3_data_hdr.pad is zero once we start setting it. */
> +	if (xfs_has_crc(sc->mp)) {
> +		struct xfs_dir3_data_hdr    *hdr3 = bp->b_addr;
> +
> +		if (hdr3->pad)
> +			xchk_fblock_set_preen(sc, XFS_DATA_FORK, lblk);

Looks good!  Thanks for patching this hole :)

Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>

--D

> +	}
>  
>  	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
>  		goto out_buf;
> -- 
> 2.50.1
> 
> 
> 
> 
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