4 files changed, 21 insertions, 10 deletions

diff --git a/sys/src/cmd/9660srv/9660srv.c b/sys/src/cmd/9660srv/9660srv.c
index 37dbd444b..8fe773d1b 100644
--- a/sys/src/cmd/9660srv/9660srv.c
+++ b/sys/src/cmd/9660srv/9660srv.c
@@ -69,7 +69,7 @@ iattach(Xfile *root)
 	dp = nil;
 	haveplan9 = 0;
 	for(i=VOLDESC;i<VOLDESC+100; i++){	/* +100 for sanity */
-		p = getbuf(cd->d, i);
+		p = getbuf(cd->d, i, 1);
 		v = (Voldesc*)(p->iobuf);
 		if(memcmp(v->byte, "\01CD001\01", 7) == 0){		/* iso */
 			if(dirp)
@@ -372,7 +372,7 @@ iread(Xfile *f, char *buf, vlong offset, long count)
 	while(count > 0){
 		if(n > count)
 			n = count;
-		p = getbuf(f->xf->d, addr);
+		p = getbuf(f->xf->d, addr, 0);
 		memmove(&buf[rcnt], &p->iobuf[o], n);
 		putbuf(p);
 		count -= n;
@@ -499,7 +499,7 @@ getdrec(Xfile *f, void *buf)
 			ip->offset += Sectorsize-boff;
 			continue;
 		}
-		p = getbuf(f->xf->d, addr/Sectorsize);
+		p = getbuf(f->xf->d, addr/Sectorsize, 1);
 		len = p->iobuf[boff];
 		if(len >= 34)
 			break;
@@ -754,7 +754,7 @@ getcontin(Xdata *dev, uchar *p, uchar **s)
 	off = l32(p+12);
 	len = l32(p+20);
 	chat("getcontin %d...", bn);
-	b = getbuf(dev, bn);
+	b = getbuf(dev, bn, 1);
 	if(b == 0){
 		*s = 0;
 		return 0;
diff --git a/sys/src/cmd/9660srv/dat.h b/sys/src/cmd/9660srv/dat.h
index bee14db61..3949251a1 100644
--- a/sys/src/cmd/9660srv/dat.h
+++ b/sys/src/cmd/9660srv/dat.h
@@ -31,6 +31,7 @@ struct Ioclust
 	int	nbuf;
 	Iobuf*	buf;
 	uchar*	iobuf;
+	ulong	tag;			/* cache tag for eviction: 0 = data, 1 = metadata */
 };
 
 struct Xdata
diff --git a/sys/src/cmd/9660srv/fns.h b/sys/src/cmd/9660srv/fns.h
index 1bae3b507..2862d5a63 100644
--- a/sys/src/cmd/9660srv/fns.h
+++ b/sys/src/cmd/9660srv/fns.h
@@ -1,7 +1,7 @@
 void	chat(char*, ...);
 void*	ealloc(long);
 void	error(char*);
-Iobuf*	getbuf(Xdata*, ulong);
+Iobuf*	getbuf(Xdata*, ulong, ulong);
 Xdata*	getxdata(char*);
 void	iobuf_init(void);
 void	nexterror(void);
diff --git a/sys/src/cmd/9660srv/iobuf.c b/sys/src/cmd/9660srv/iobuf.c
index 6bba533e8..a617483e6 100644
--- a/sys/src/cmd/9660srv/iobuf.c
+++ b/sys/src/cmd/9660srv/iobuf.c
@@ -31,7 +31,7 @@ int nclust = NCLUST;
 static Ioclust*	iohead;
 static Ioclust*	iotail;
 
-static Ioclust*	getclust(Xdata*, long);
+static Ioclust*	getclust(Xdata*, long, ulong);
 static void	putclust(Ioclust*);
 static void	xread(Ioclust*);
 
@@ -53,6 +53,16 @@ iobuf_init(void)
 	for(i=0; i<nclust; i++){
 		c = (Ioclust*)mem;
 		mem += sizeof(Ioclust);
+
+		/*
+		 * on a iso filesystem, data is usually layed out sequentially
+		 * but directory information is at the end of the disk. to avoid
+		 * evicting directory information when reading large sequential
+		 * files, we keep them tagged in the cache. for now, we use
+		 * an 8th of the clusters for meta data.
+		 */
+		c->tag = i <= (nclust/8);
+
 		c->addr = -1;
 		c->prev = iotail;
 		if(iotail)
@@ -87,13 +97,13 @@ purgebuf(Xdata *dev)
 }
 
 static Ioclust*
-getclust(Xdata *dev, long addr)
+getclust(Xdata *dev, long addr, ulong tag)
 {
 	Ioclust *c, *f;
 
 	f = nil;
 	for(c=iohead; c; c=c->next){
-		if(!c->busy)
+		if(!c->busy && c->tag == tag)
 			f = c;
 		if(c->addr == addr && c->dev == dev){
 			c->busy++;
@@ -141,13 +151,13 @@ putclust(Ioclust *c)
 }
 
 Iobuf*
-getbuf(Xdata *dev, ulong addr)
+getbuf(Xdata *dev, ulong addr, ulong tag)
 {
 	int off;
 	Ioclust *c;
 
 	off = addr%BUFPERCLUST;
-	c = getclust(dev, addr - off);
+	c = getclust(dev, addr - off, tag);
 	if(c->nbuf < off){
 		c->busy--;
 		error("I/O read error");