EXTENT_BUFFER_READING
if (test_bit(EXTENT_BUFFER_READING, &eb->bflags))
wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_READING,
clear_and_wake_up_bit(EXTENT_BUFFER_READING, &eb->bflags);
if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags))
wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_READING, TASK_UNINTERRUPTIBLE);