[PATCH 2/2] xfs: check btree keys reflect the child block

Darrick J. Wong
2022-10-02T18:32:14Z

From: Darrick J. Wong <djwong@kernel.org>

When scrub is checking a non-root btree block, it should make sure that
the keys in the parent btree block accurately capture the keyspace that
the child block stores.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/scrub/btree.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/scrub/btree.c b/fs/xfs/scrub/btree.c
index 47fa14311d17..2e2aa0773858 100644
--- a/fs/xfs/scrub/btree.c
+++ b/fs/xfs/scrub/btree.c
@@ -517,6 +517,48 @@ xchk_btree_check_minrecs(
xchk_btree_set_corrupt(bs->sc, cur, level);
}

+/*
+ * If this btree block has a parent, make sure that the parent's keys capture
+ * the keyspace contained in this block.
+ */
+STATIC void
+xchk_btree_block_check_keys(
+ struct xchk_btree *bs,
+ int level,
+ struct xfs_btree_block *block)
+{
+ union xfs_btree_key block_key;
+ union xfs_btree_key *block_high_key;
+ union xfs_btree_key *parent_low_key, *parent_high_key;
+ struct xfs_btree_cur *cur = bs->cur;
+ struct xfs_btree_block *parent_block;
+ struct xfs_buf *bp;
+
+ if (level == cur->bc_nlevels - 1)
+ return;
+
+ xfs_btree_get_keys(cur, block, &block_key);
+
+ /* Make sure the low key of this block matches the parent. */
+ parent_block = xfs_btree_get_block(cur, level + 1, &bp);
+ parent_low_key = xfs_btree_key_addr(cur, cur->bc_levels[level + 1].ptr,
+ parent_block);
+ if (cur->bc_ops->diff_two_keys(cur, &block_key, parent_low_key)) {
+ xchk_btree_set_corrupt(bs->sc, bs->cur, level);
+ return;
+ }
+
+ if (!(cur->bc_flags & XFS_BTREE_OVERLAPPING))
+ return;
+
+ /* Make sure the high key of this block matches the parent. */
+ parent_high_key = xfs_btree_high_key_addr(cur,
+ cur->bc_levels[level + 1].ptr, parent_block);
+ block_high_key = xfs_btree_high_key_from_key(cur, &block_key);
+ if (cur->bc_ops->diff_two_keys(cur, block_high_key, parent_high_key))
+ xchk_btree_set_corrupt(bs->sc, bs->cur, level);
+}
+
/*
* Grab and scrub a btree block given a btree pointer. Returns block
* and buffer pointers (if applicable) if they're ok to use.
@@ -568,7 +610,12 @@ xchk_btree_get_block(
* Check the block's siblings; this function absorbs error codes
* for us.
*/
- return xchk_btree_block_check_siblings(bs, *pblock);
+ error = xchk_btree_block_check_siblings(bs, *pblock);
+ if (error)
+ return error;
+
+ xchk_btree_block_check_keys(bs, level, *pblock);
+ return 0;
}

/*