git: 9front

Download patch

ref: b545b52288e15df17f52540ba3bea8b63a59b72e
parent: badccaac1f28808607395612e96d5eade50b764d
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Mon Dec 15 01:28:27 EST 2014 

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.


--- a/sys/src/9/port/cache.c
+++ b/sys/src/9/port/cache.c
@@ -16,7 +16,7 @@
 typedef struct Extent Extent;
 struct Extent
 {
-	int	bid;
+	uintptr	bid;
 	ulong	start;
 	int	len;
 	Page	*cache;
@@ -40,7 +40,7 @@
 struct Cache
 {
 	Lock;
-	int		pgno;
+	uintptr		pgno;
 	Mntcache	*head;
 	Mntcache	*tail;
 	Mntcache	*hash[NHASH];
@@ -59,7 +59,7 @@
 
 static Cache cache;
 static Ecache ecache;
-static int maxcache = MAXCACHE;
+static ulong maxcache = MAXCACHE;
 
 static void
 extentfree(Extent* e)
@@ -89,16 +89,17 @@
 			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;
 }
 
@@ -124,23 +125,23 @@
 	}
 
 	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;
@@ -147,38 +148,38 @@
 
 	/*
 	 * 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 @@
 {
 	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 @@
 
 	/* 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 @@
 	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 @@
 		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 @@
 	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 @@
 	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 @@
 		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 @@
 	return total;
 }
 
-Extent*
+static Extent*
 cchain(uchar *buf, ulong offset, int len, Extent **tail)
 {
 	int l;
@@ -358,16 +358,16 @@
 	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;
 		}
@@ -417,7 +417,7 @@
 	return start;
 }
 
-int
+static int
 cpgmove(Extent *e, uchar *buf, int boff, int len)
 {
 	Page *p;
@@ -424,7 +424,7 @@
 	KMap *k;
 
 	p = cpage(e);
-	if(p == 0)
+	if(p == nil)
 		return 0;
 
 	k = kmap(p);
@@ -445,17 +445,17 @@
 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;
 
 	/*
@@ -462,8 +462,8 @@
 	 * 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 @@
 
 	/* 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 @@
 	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 @@
 			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);
 }
 
@@ -535,15 +530,14 @@
 {
 	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;
@@ -550,14 +544,14 @@
 	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 @@
 
 	/* 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 @@
 
 	/* 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;
-- 
⑨