xfs: btree lookup shouldn't ASSERT on empty btree nodes

If a btree lookup encounters an empty btree node or an empty btree leaf
on a multi-level btree, that's evidence of a corrupt on-disk btree.
Therefore, we should return -EFSCORRUPTED to the upper levels, not an
ASSERT failure.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index c825c81..3d59eb6 100644 (file)
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -1896,7 +1896,12 @@ xfs_btree_lookup(
                        high = xfs_btree_get_numrecs(block);
                        if (!high) {
                                /* Block is empty, must be an empty leaf. */
-                               ASSERT(level == 0 && cur->bc_nlevels == 1);
+                               if (level != 0 || cur->bc_nlevels != 1) {
+                                       XFS_CORRUPTION_ERROR(__func__,
+                                                       XFS_ERRLEVEL_LOW,
+                                                       cur->bc_mp, block);
+                                       return -EFSCORRUPTED;
+                               }
 
                                cur->bc_ptrs[0] = dir != XFS_LOOKUP_LE;
                                *stat = 0;