bcachefs: Filter out harmless EROFS error messages

These just indicate that we're shutting down.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Author: Kent Overstreet

fs/bcachefs/move.c

@@ -784,7 +784,8 @@ static int __bch2_move_data_phys(struct moving_context *ctxt,
 		goto err;
 
 	ret = bch2_btree_write_buffer_tryflush(trans);
-	bch_err_msg(c, ret, "flushing btree write buffer");
+	if (!bch2_err_matches(ret, EROFS))
+		bch_err_msg(c, ret, "flushing btree write buffer");
 	if (ret)
 		goto err;