From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Strengthen the btree block header checks to detect the number of records
being less than the btree type's minimum record count. Certain blocks
are allowed to violate this constraint -- specifically any btree block
at the top of the tree can have fewer than minrecs records.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
---
fs/xfs/scrub/btree.c | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/fs/xfs/scrub/btree.c b/fs/xfs/scrub/btree.c
index ea972dab1485..2d29dceaa00e 100644
--- a/fs/xfs/scrub/btree.c
+++ b/fs/xfs/scrub/btree.c
@@ -454,6 +454,44 @@ xfs_scrub_btree_check_owner(
return xfs_scrub_btree_check_block_owner(bs, level, XFS_BUF_ADDR(bp));
}
+/*
+ * Check that this btree block has at least minrecs records or is one of the
+ * special blocks that don't require that.
+ */
+STATIC void
+xfs_scrub_btree_check_minrecs(
+ struct xfs_scrub_btree *bs,
+ int level,
+ struct xfs_btree_block *block)
+{
+ unsigned int numrecs;
+ int ok_level;
+
+ numrecs = be16_to_cpu(block->bb_numrecs);
+
+ /* More records than minrecs means the block is ok. */
+ if (numrecs >= bs->cur->bc_ops->get_minrecs(bs->cur, level))
+ return;
+
+ /*
+ * Certain btree blocks /can/ have fewer than minrecs records. Any
+ * level greater than or equal to the level of the highest dedicated
+ * btree block are allowed to violate this constraint.
+ *
+ * For a btree rooted in a block, the btree root can have fewer than
+ * minrecs records. If the btree is rooted in an inode and does not
+ * store records in the root, the direct children of the root and the
+ * root itself can have fewer than minrecs records.
+ */
+ ok_level = bs->cur->bc_nlevels - 1;
+ if (bs->cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
+ ok_level--;
+ if (level >= ok_level)
+ return;
+
+ xfs_scrub_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.
@@ -491,6 +529,8 @@ xfs_scrub_btree_get_block(
if (*pbp)
xfs_scrub_buffer_recheck(bs->sc, *pbp);
+ xfs_scrub_btree_check_minrecs(bs, level, *pblock);
+
/*
* Check the block's owner; this function absorbs error codes
* for us.
--
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