From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
In xrep_findroot_block, if we find a candidate root block with sibling
pointers or sibling blocks on the same tree level, we should not return
that block as a tree root because root blocks cannot have siblings.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/xfs/scrub/repair.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 85b048b341a0..6c199e2ebb81 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -727,6 +727,23 @@ xrep_findroot_block(
bp->b_ops->verify_read(bp);
if (bp->b_error)
goto out;
+
+ /* Root blocks can't have siblings. */
+ if (btblock->bb_u.s.bb_leftsib != cpu_to_be32(NULLAGBLOCK) ||
+ btblock->bb_u.s.bb_rightsib != cpu_to_be32(NULLAGBLOCK))
+ goto out;
+
+ /*
+ * If we find a second block at this level, ignore this level because
+ * it can't possibly be a root level. Maybe we'll find a higher level,
+ * or maybe the rmap information is garbage.
+ */
+ if (fab->root != NULLAGBLOCK &&
+ fab->height == xfs_btree_get_level(btblock) + 1) {
+ fab->root = NULLAGBLOCK;
+ goto out;
+ }
+
fab->root = agbno;
fab->height = xfs_btree_get_level(btblock) + 1;
*found_it = true;
--
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