extent_buffer_under_io
if (unlikely(refcount_read(&eb->refs) > 2 || extent_buffer_under_io(eb))) {
ASSERT(!extent_buffer_under_io(eb));
!extent_buffer_under_io(eb) &&
if (refcount_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) &&
if (refcount_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {
if (refcount_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {