kernel: remove waserror() arround newpage() in mntcache

[plan9front.git] / sys / src / 9 / port / cache.c

diff --git a/sys/src/9/port/cache.c b/sys/src/9/port/cache.c
index a64088abf10a007838be93a672da51cc9989c31a..e1f449df4ab0dcb597df03754f54d2acd6d663b7 100644 (file)
--- a/sys/src/9/port/cache.c
+++ b/sys/src/9/port/cache.c
@@ -205,6 +205,11 @@ ccache(Chan *c)
        return nil;
 }
 
+enum {
+       VABITS  = 8*sizeof(uintptr) - 2*PGSHIFT,
+       VAMASK  = (((uintptr)1 << VABITS)-1) << PGSHIFT,
+};
+
 static Page*
 cpage(Mntcache *m, ulong pn, ulong *po, ulong *pe)
 {
@@ -219,12 +224,19 @@ cpage(Mntcache *m, ulong pn, ulong *po, ulong *pe)
                m->bitmap[pn/MAPBITS] &= ~b;
                return nil;
        }
-       /* see cachedata() below */
-       *po = (ulong)p->va & (BY2PG-1);
-       *pe = (ulong)p->va >> PGSHIFT;
+       *po = p->va & (BY2PG-1);
+       *pe = 1 + (p->va >> (PGSHIFT+VABITS));
+       assert(*po < *pe);
        return p;
 }
 
+static void
+cpageset(Page *p, ulong po, ulong pe)
+{
+       assert(po < pe);
+       p->va = po | (p->va & VAMASK) | ((uintptr)pe - 1) << (PGSHIFT+VABITS);
+}
+
 int
 cread(Chan *c, uchar *buf, int len, vlong off)
 {
@@ -253,7 +265,7 @@ cread(Chan *c, uchar *buf, int len, vlong off)
                p = cpage(m, pn, &po, &pe);
                if(p == nil)
                        break;
-               if(po >= pe || offset < po || offset >= pe){
+               if(offset < po || offset >= pe){
                        putpage(p);
                        break;
                }
@@ -326,8 +338,8 @@ cachedata(Mntcache *m, uchar *buf, int len, vlong off)
                        l = len;
                p = cpage(m, pn, &po, &pe);
                if(p != nil){
-                       if(po >= pe || offset > pe || (offset+l) < po){
-                               /* cached range empty or not extendable, set new cached range */
+                       if(offset > pe || (offset+l) < po){
+                               /* cached range not extendable, set new cached range */
                                po = offset;
                                pe = offset+l;
                        } else {
@@ -338,13 +350,11 @@ cachedata(Mntcache *m, uchar *buf, int len, vlong off)
                                        pe = offset+l;
                        }
                } else {
-                       p = auxpage();
-                       if(p == nil){
+                       if(needpages(nil)){
                                invalidate(m, offset + pn*BY2PG, len);
                                break;
                        }
-
-                       p->va = 0;
+                       p = newpage(0, nil, pn*BY2PG);
                        p->daddr = cacheaddr(m, pn);
                        cachedel(&fscache, p->daddr);
                        cachepage(p, &fscache);
@@ -353,6 +363,7 @@ cachedata(Mntcache *m, uchar *buf, int len, vlong off)
                        po = offset;
                        pe = offset+l;
                }
+               cpageset(p, po, pe);
 
                k = kmap(p);
                if(waserror()) {
@@ -365,9 +376,6 @@ cachedata(Mntcache *m, uchar *buf, int len, vlong off)
                memmove((uchar*)VA(k) + offset, buf, l);
                poperror();
                kunmap(k);
-
-               /* update cached range */
-               p->va = po | (pe << PGSHIFT);
                putpage(p);
 
                offset = 0;