buffer_heads_over_limit
int buffer_heads_over_limit;
buffer_heads_over_limit = (tot > max_buffer_heads);
if (buffer_heads_over_limit && folio_test_uptodate(folio))
extern int buffer_heads_over_limit;
if (unlikely(buffer_heads_over_limit)) {
if (buffer_heads_over_limit) {
if (buffer_heads_over_limit) {