preempt_disable(); __get_cpu_var(bh_accounting).nr--;
get_cpu_var(bh_accounting).nr--;
void free_buffer_head(struct buffer_head *bh){	BUG_ON(!list_empty(&bh->b_assoc_buffers));	kmem_cache_free(bh_cachep, bh);	preempt_disable();	__get_cpu_var(bh_accounting).nr--;	recalc_bh_state();	preempt_enable();}