kernel: minor changes to mount cache

change page cache ids (bid) to uintptr so we use the full
address space of Page.daddr.

make maxcache offset check consistent in cread().

use consistent types in cupdate() and simplify with goto.

make internal functions static.

use nil instead of 0 for pointers.

1 files changed, 72 insertions, 78 deletions

diff --git a/sys/src/9/port/cache.c b/sys/src/9/port/cache.c
index 22ba52fbc..4391a026d 100644
--- a/sys/src/9/port/cache.c
+++ b/sys/src/9/port/cache.c
@@ -16,7 +16,7 @@ enum
 typedef struct Extent Extent;
 struct Extent
 {
-	int	bid;
+	uintptr	bid;
 	ulong	start;
 	int	len;
 	Page	*cache;
@@ -40,7 +40,7 @@ typedef struct Cache Cache;
 struct Cache
 {
 	Lock;
-	int		pgno;
+	uintptr		pgno;
 	Mntcache	*head;
 	Mntcache	*tail;
 	Mntcache	*hash[NHASH];
@@ -59,7 +59,7 @@ Image fscache;
 
 static Cache cache;
 static Ecache ecache;
-static int maxcache = MAXCACHE;
+static ulong maxcache = MAXCACHE;
 
 static void
 extentfree(Extent* e)
@@ -89,16 +89,17 @@ extentalloc(void)
 			ecache.head = e;
 			e++;
 		}
-		ecache.free += NEXTENT;
 		ecache.total += NEXTENT;
+		ecache.free += NEXTENT;
 	}
 
 	e = ecache.head;
 	ecache.head = e->next;
-	memset(e, 0, sizeof(Extent));
 	ecache.free--;
 	unlock(&ecache);
 
+	memset(e, 0, sizeof(Extent));
+
 	return e;
 }
 
@@ -124,61 +125,61 @@ cinit(void)
 	}
 
 	cache.tail = m;
-	cache.tail->next = 0;
-	cache.head->prev = 0;
+	cache.tail->next = nil;
+	cache.head->prev = nil;
 
 	fscache.notext = 1;
 }
 
-Page*
+static Page*
 cpage(Extent *e)
 {
 	/* Easy consistency check */
 	if(e->cache->daddr != e->bid)
-		return 0;
+		return nil;
 
 	return lookpage(&fscache, e->bid);
 }
 
-void
+static void
 cnodata(Mntcache *m)
 {
 	Extent *e;
 
 	/*
 	 * Invalidate all extent data
-	 * Image lru will waste the pages
+	 * pagereclaim() will waste the pages
 	 */
-	while(e = m->list){
+	while((e = m->list) != nil){
 		m->list = e->next;
 		extentfree(e);
 	}
 }
 
-void
+static void
 ctail(Mntcache *m)
 {
 	/* Unlink and send to the tail */
-	if(m->prev)
+	if(m->prev != nil)
 		m->prev->next = m->next;
 	else
 		cache.head = m->next;
-	if(m->next)
+	if(m->next != nil)
 		m->next->prev = m->prev;
 	else
 		cache.tail = m->prev;
 
-	if(cache.tail) {
+	if(cache.tail != nil) {
 		m->prev = cache.tail;
 		cache.tail->next = m;
-		m->next = 0;
+		m->next = nil;
 		cache.tail = m;
 	}
 	else {
 		cache.head = m;
 		cache.tail = m;
-		m->prev = 0;
-		m->next = 0;
+		m->prev = nil;
+		m->next = nil;
 	}
 }
 
@@ -188,11 +189,11 @@ clookup(Chan *c, int skipvers)
 {
 	Mntcache *m;
 
-	for(m = cache.hash[c->qid.path%NHASH]; m; m = m->hash)
+	for(m = cache.hash[c->qid.path%NHASH]; m != nil; m = m->hash)
 		if(eqchantdqid(c, m->type, m->dev, m->qid, skipvers) && c->qid.type == m->qid.type)
 			return m;
 
-	return 0;
+	return nil;
 }
 
 void
@@ -202,13 +203,13 @@ copen(Chan *c)
 
 	/* directories aren't cacheable and append-only files confuse us */
 	if(c->qid.type&(QTDIR|QTAPPEND)){
-		c->mcp = 0;
+		c->mcp = nil;
 		return;
 	}
 
 	lock(&cache);
 	m = clookup(c, 1);
-	if(m == 0)
+	if(m == nil)
 		m = cache.head;
 	else if(m->qid.vers == c->qid.vers) {
 		ctail(m);
@@ -219,7 +220,7 @@ copen(Chan *c)
 	ctail(m);
 
 	l = &cache.hash[m->qid.path%NHASH];
-	for(f = *l; f; f = f->hash) {
+	for(f = *l; f != nil; f = f->hash) {
 		if(f == m) {
 			*l = m->hash;
 			break;
@@ -232,7 +233,7 @@ copen(Chan *c)
 		qlock(m);
 		lock(&cache);
 		f = clookup(c, 0);
-		if(f != 0) {
+		if(f != nil) {
 			/*
 			 * someone got there first while cache lock
 			 * was released and added a updated Mntcache
@@ -266,14 +267,14 @@ ccache(Chan *c)
 	Mntcache *m;
 
 	m = c->mcp;
-	if(m) {
+	if(m != nil) {
 		qlock(m);
 		if(eqchantdqid(c, m->type, m->dev, m->qid, 0) && c->qid.type == m->qid.type)
 			return m;
-		c->mcp = 0;
+		c->mcp = nil;
 		qunlock(m);
 	}
-	return 0;
+	return nil;
 }
 
 int
@@ -286,34 +287,33 @@ cread(Chan *c, uchar *buf, int len, vlong off)
 	int o, l, total;
 	ulong offset;
 
-	if(off+len > maxcache)
+	if(off >= maxcache || len <= 0)
 		return 0;
 
 	m = ccache(c);
-	if(m == 0)
+	if(m == nil)
 		return 0;
 
 	offset = off;
 	t = &m->list;
-	for(e = *t; e; e = e->next) {
+	for(e = *t; e != nil; e = e->next) {
 		if(offset >= e->start && offset < e->start+e->len)
 			break;
 		t = &e->next;
 	}
 
-	if(e == 0) {
+	if(e == nil) {
 		qunlock(m);
 		return 0;
 	}
 
 	total = 0;
-	while(len) {
+	while(len > 0) {
 		p = cpage(e);
-		if(p == 0) {
+		if(p == nil) {
 			*t = e->next;
 			extentfree(e);
-			qunlock(m);
-			return total;
+			break;
 		}
 
 		o = offset - e->start;
@@ -342,7 +342,7 @@ cread(Chan *c, uchar *buf, int len, vlong off)
 		total += l;
 		t = &e->next;
 		e = e->next;
-		if(e == 0 || e->start != offset)
+		if(e == nil || e->start != offset)
 			break;
 	}
 
@@ -350,7 +350,7 @@ cread(Chan *c, uchar *buf, int len, vlong off)
 	return total;
 }
 
-Extent*
+static Extent*
 cchain(uchar *buf, ulong offset, int len, Extent **tail)
 {
 	int l;
@@ -358,16 +358,16 @@ cchain(uchar *buf, ulong offset, int len, Extent **tail)
 	KMap *k;
 	Extent *e, *start, **t;
 
-	start = 0;
-	*tail = 0;
+	start = nil;
+	*tail = nil;
 	t = &start;
-	while(len) {
+	while(len > 0) {
 		e = extentalloc();
-		if(e == 0)
+		if(e == nil)
 			break;
 
 		p = auxpage();
-		if(p == 0) {
+		if(p == nil) {
 			extentfree(e);
 			break;
 		}
@@ -417,14 +417,14 @@ cchain(uchar *buf, ulong offset, int len, Extent **tail)
 	return start;
 }
 
-int
+static int
 cpgmove(Extent *e, uchar *buf, int boff, int len)
 {
 	Page *p;
 	KMap *k;
 
 	p = cpage(e);
-	if(p == 0)
+	if(p == nil)
 		return 0;
 
 	k = kmap(p);
@@ -445,25 +445,25 @@ cpgmove(Extent *e, uchar *buf, int boff, int len)
 void
 cupdate(Chan *c, uchar *buf, int len, vlong off)
 {
+	int o;
 	Mntcache *m;
 	Extent *tail;
 	Extent *e, *f, *p;
-	int o, ee, eblock;
-	ulong offset;
+	ulong offset, eblock, ee;
 
-	if(off > maxcache || len == 0)
+	if(off >= maxcache || len <= 0)
 		return;
 
 	m = ccache(c);
-	if(m == 0)
+	if(m == nil)
 		return;
 
 	/*
 	 * Find the insertion point
 	 */
 	offset = off;
-	p = 0;
-	for(f = m->list; f; f = f->next) {
+	p = nil;
+	for(f = m->list; f != nil; f = f->next) {
 		if(f->start > offset)
 			break;
 		p = f;
@@ -471,22 +471,19 @@ cupdate(Chan *c, uchar *buf, int len, vlong off)
 
 	/* trim if there is a successor */
 	eblock = offset+len;
-	if(f != 0 && eblock > f->start) {
+	if(f != nil && eblock > f->start) {
 		len -= (eblock - f->start);
-		if(len <= 0) {
-			qunlock(m);
-			return;
-		}
+		if(len <= 0)
+			goto out;
 	}
 
-	if(p == 0) {		/* at the head */
+	if(p == nil) {		/* at the head */
 		e = cchain(buf, offset, len, &tail);
-		if(e != 0) {
+		if(e != nil) {
 			m->list = e;
 			tail->next = f;
 		}
-		qunlock(m);
-		return;
+		goto out;
 	}
 
 	/* trim to the predecessor */
@@ -494,10 +491,8 @@ cupdate(Chan *c, uchar *buf, int len, vlong off)
 	if(offset < ee) {
 		o = ee - offset;
 		len -= o;
-		if(len <= 0) {
-			qunlock(m);
-			return;
-		}
+		if(len <= 0)
+			goto out;
 		buf += o;
 		offset += o;
 	}
@@ -513,20 +508,20 @@ cupdate(Chan *c, uchar *buf, int len, vlong off)
 			len -= o;
 			offset += o;
 			if(len <= 0) {
-				if(f && p->start + p->len > f->start)
+				if(f != nil && p->start + p->len > f->start)
 					print("CACHE: p->start=%uld p->len=%d f->start=%uld\n",
 						p->start, p->len, f->start);
-				qunlock(m);
-				return;
+				goto out;
 			}
 		}
 	}
 
 	e = cchain(buf, offset, len, &tail);
-	if(e != 0) {
+	if(e != nil) {
 		p->next = e;
 		tail->next = f;
 	}
+out:
 	qunlock(m);
 }
 
@@ -535,29 +530,28 @@ cwrite(Chan* c, uchar *buf, int len, vlong off)
 {
 	int o, eo;
 	Mntcache *m;
-	ulong eblock, ee;
 	Extent *p, *f, *e, *tail;
-	ulong offset;
+	ulong offset, eblock, ee;
 
-	if(off > maxcache || len == 0)
+	if(off >= maxcache || len <= 0)
 		return;
 
 	m = ccache(c);
-	if(m == 0)
+	if(m == nil)
 		return;
 
 	offset = off;
 	m->qid.vers++;
 	c->qid.vers++;
 
-	p = 0;
-	for(f = m->list; f; f = f->next) {
+	p = nil;
+	for(f = m->list; f != nil; f = f->next) {
 		if(f->start >= offset)
 			break;
 		p = f;
 	}
 
-	if(p != 0) {
+	if(p != nil) {
 		ee = p->start+p->len;
 		eo = offset - p->start;
 		/* pack in predecessor if there is space */
@@ -577,7 +571,7 @@ cwrite(Chan* c, uchar *buf, int len, vlong off)
 
 	/* free the overlap -- it's a rare case */
 	eblock = offset+len;
-	while(f && f->start < eblock) {
+	while(f != nil && f->start < eblock) {
 		e = f->next;
 		extentfree(f);
 		f = e;
@@ -585,12 +579,12 @@ cwrite(Chan* c, uchar *buf, int len, vlong off)
 
 	/* link the block (if any) into the middle */
 	e = cchain(buf, offset, len, &tail);
-	if(e != 0) {
+	if(e != nil) {
 		tail->next = f;
 		f = e;
 	}
 
-	if(p == 0)
+	if(p == nil)
 		m->list = f;
 	else
 		p->next = f;