Re: [syzbot] [bcachefs?] kernel BUG in vfs_get_tree

[Edward Adam Davis]

kthread_run return -EINTR in read_btree_nodes(), it needs to be returnned
to bch2_fs_recovery(), not back to "ret = IS_ERR_OR_NULL(t)".

#syz test

diff --git a/fs/bcachefs/btree_node_scan.c b/fs/bcachefs/btree_node_scan.c
index b28c649c6838..aa0f84d35895 100644
--- a/fs/bcachefs/btree_node_scan.c
+++ b/fs/bcachefs/btree_node_scan.c
@@ -280,12 +280,15 @@ static int read_btree_nodes(struct find_btree_nodes *f)
 			percpu_ref_put(&ca->io_ref);
 			closure_put(&cl);
 			f->ret = ret;
-			bch_err(c, "error starting kthread: %i", ret);
+			bch_err(c, "error starting kthread: %i %d", ret, PTR_ERR(t));
 			break;
 		}
 	}
 err:
 	closure_sync(&cl);
+	if (IS_ERR(t))
+		return PTR_ERR(t);
+
 	return f->ret ?: ret;
 }