[PATCH v3] xfs: check da node block pad field during scrub

Yuto Ohnuki
2026-04-10T17:06:28Z

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 v3:
- Drop unnecessary be32_to_cpu() on comparison to zero.
- Link to v2: https://lore.kernel.org/all/20260408174033.4165-2-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..c2d6ad59d03e 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 (nodehdr3->__pad32)
+ xchk_da_set_preen(ds, level);
+ }
break;
default:
xchk_da_set_corrupt(ds, level);
--
2.50.1

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