Btrfs: kill BUG_ON in run_delayed_tree_ref

In a corrupted btrfs image, we can come across this BUG_ON and
get an unreponsive system, but if we return errors instead,
its caller can handle everything gracefully by aborting the current
transaction.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 73fb91f9d797c2b2ea4f4b744d7ee7169e1e70ed..3d3b193a396c1233a95cd9fcae602167e89137f6 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2352,7 +2352,13 @@ static int run_delayed_tree_ref(struct btrfs_trans_handle *trans,
                ins.type = BTRFS_EXTENT_ITEM_KEY;
        }
 
-       BUG_ON(node->ref_mod != 1);
+       if (node->ref_mod != 1) {
+               btrfs_err(root->fs_info,
+       "btree block(%llu) has %d references rather than 1: action %d ref_root %llu parent %llu",
+                         node->bytenr, node->ref_mod, node->action, ref_root,
+                         parent);
+               return -EIO;
+       }
        if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
                BUG_ON(!extent_op || !extent_op->update_flags);
                ret = alloc_reserved_tree_block(trans, root,