#include <u.h>#include <libc.h>#include <thread.h>#include <venti.h>#include <diskfs.h>#include "queue.h" Queue*qalloc(void){	Queue *q; 	q = vtmallocz(sizeof(Queue));	q->r.l = &q->lk;	return q;} Block*qread(Queue *q, u32int *pbno){	Block *db;	u32int bno; 	qlock(&q->lk);	while(q->nel == 0 && !q->closed)		rsleep(&q->r);	if(q->nel == 0 && q->closed){		qunlock(&q->lk);		return nil;	}	db = q->el[q->ri].db;	bno = q->el[q->ri].bno;	if(++q->ri == MAXQ)		q->ri = 0;	if(q->nel-- == MAXQ/2)		rwakeup(&q->r);	qunlock(&q->lk);	*pbno = bno;	return db;} voidqwrite(Queue *q, Block *db, u32int bno){	qlock(&q->lk);	while(q->nel == MAXQ)		rsleep(&q->r);	q->el[q->wi].db = db;	q->el[q->wi].bno = bno;	if(++q->wi == MAXQ)		q->wi = 0;	if(q->nel++ == MAXQ/2)		rwakeup(&q->r);	qunlock(&q->lk);} voidqclose(Queue *q){	qlock(&q->lk);	q->closed = 1;	rwakeup(&q->r);	qunlock(&q->lk);} voidqfree(Queue *q){	vtfree(q);}