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 so that non-zero padding is flagged as
corruption.

Signed-off-by: Yuto Ohnuki <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..73d5a3bd936a 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_corrupt(ds, level);
+		}
 		break;
 	default:
 		xchk_da_set_corrupt(ds, level);
-- 
2.50.1




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On Sat, Apr 04, 2026 at 03:30:44PM +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 so that non-zero padding is flagged as
> corruption.
> 
> Signed-off-by: Yuto Ohnuki <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..73d5a3bd936a 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. */

Same question as the previous patch -- does xfs_da3_node_create actually
zero out the pad field?

> +		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_corrupt(ds, level);

and same comment about how you can only set xchk_da_set_preen if old
kernels were ok with nonzero __pad32.

--D

> +		}
>  		break;
>  	default:
>  		xchk_da_set_corrupt(ds, level);
> -- 
> 2.50.1
> 
> 
> 
> 
> Amazon Web Services EMEA SARL, 38 avenue John F. Kennedy, L-1855 Luxembourg, R.C.S. Luxembourg B186284
> 
> Amazon Web Services EMEA SARL, Irish Branch, One Burlington Plaza, Burlington Road, Dublin 4, Ireland, branch registration number 908705
> 
> 
> 
>

On Mon, Apr 06, 2026 at 08:23:04AM -0700, Darrick J. Wong wrote:

Thank you for reviewing this patch as well.

> Same question as the previous patch -- does xfs_da3_node_create actually
> zero out the pad field?

Yes, xfs_da3_node_create already does
memset(hdr3, 0, sizeof(struct xfs_da3_node_hdr)) which covers __pad32.

> and same comment about how you can only set xchk_da_set_preen if old
> kernels were ok with nonzero __pad32.
> 
> --D
> 

Understood. I'll switch to xchk_da_set_preen as well.

I'll send a v2 with this change.

Thanks,
Yuto



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