The da node block header (xfs_da3_node_hdr) contains a __pad32 field
that should always be zero. Add a check for this during directory and
attribute btree scrubbing.

Since old kernels may have written non-zero padding without issues, flag
this as an optimization opportunity (preen) rather than corruption.

Signed-off-by: Yuto Ohnuki <ytohnuki@amazon.com>
---
Changes in v2:
- Use xchk_da_set_preen instead of xchk_da_set_corrupt since
  old kernels may have written non-zero padding without issues.
- Link to v1: https://lore.kernel.org/all/20260404143043.65268-2-ytohnuki@amazon.com/
---
 fs/xfs/scrub/dabtree.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/scrub/dabtree.c b/fs/xfs/scrub/dabtree.c
index 1a71d36898b1..b55922d3e988 100644
--- a/fs/xfs/scrub/dabtree.c
+++ b/fs/xfs/scrub/dabtree.c
@@ -454,7 +454,12 @@ xchk_da_btree_block(
 			}
 		}
 
-		/* XXX: Check hdr3.pad32 once we know how to fix it. */
+		if (xfs_has_crc(ip->i_mount)) {
+			struct xfs_da3_node_hdr *nodehdr3 = blk->bp->b_addr;
+
+			if (be32_to_cpu(nodehdr3->__pad32) != 0)
+				xchk_da_set_preen(ds, level);
+		}
 		break;
 	default:
 		xchk_da_set_corrupt(ds, level);
-- 
2.50.1




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Amazon Web Services EMEA SARL, Irish Branch, One Burlington Plaza, Burlington Road, Dublin 4, Ireland, branch registration number 908705

On Wed, Apr 08, 2026 at 06:40:34PM +0100, Yuto Ohnuki wrote:
> The da node block header (xfs_da3_node_hdr) contains a __pad32 field
> that should always be zero. Add a check for this during directory and
> attribute btree scrubbing.
> 
> Since old kernels may have written non-zero padding without issues, flag
> this as an optimization opportunity (preen) rather than corruption.
> 
> Signed-off-by: Yuto Ohnuki <ytohnuki@amazon.com>
> ---
> Changes in v2:
> - Use xchk_da_set_preen instead of xchk_da_set_corrupt since
>   old kernels may have written non-zero padding without issues.
> - Link to v1: https://lore.kernel.org/all/20260404143043.65268-2-ytohnuki@amazon.com/
> ---
>  fs/xfs/scrub/dabtree.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/scrub/dabtree.c b/fs/xfs/scrub/dabtree.c
> index 1a71d36898b1..b55922d3e988 100644
> --- a/fs/xfs/scrub/dabtree.c
> +++ b/fs/xfs/scrub/dabtree.c
> @@ -454,7 +454,12 @@ xchk_da_btree_block(
>  			}
>  		}
>  
> -		/* XXX: Check hdr3.pad32 once we know how to fix it. */
> +		if (xfs_has_crc(ip->i_mount)) {
> +			struct xfs_da3_node_hdr *nodehdr3 = blk->bp->b_addr;
> +
> +			if (be32_to_cpu(nodehdr3->__pad32) != 0)
> +				xchk_da_set_preen(ds, level);
> +		}

Endian conversion not necessary on comaprison to zero.

-Dave.
-- 
Dave Chinner
dgc@kernel.org

On Thu, Apr 09, 2026 at 07:40:17AM +1000, Dave Chinner wrote:
> Endian conversion not necessary on comaprison to zero.
> 
> -Dave.
> -- 
> Dave Chinner
> dgc@kernel.org

Understood. I'll send v3 without endian conversion.

Thank you for the review.
Yuto



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