void
copen(Chan *c)
{
int h;
Mntcache *m, *f, **l;
/* directories aren't cacheable and append-only files confuse us */
if(c->qid.type&(QTDIR|QTAPPEND))
return;
h = c->qid.path%NHASH;
lock(&cache);
for(m = cache.hash[h]; m; m = m->hash) {
if(m->qid.path == c->qid.path)
if(m->qid.type == c->qid.type)
if(m->dev == c->dev && m->type == c->type) {
/* File was updated, invalidate cache */
if(m->qid.vers != c->qid.vers){
if(!canqlock(m))
goto Busy;
m->qid.vers = c->qid.vers;
goto Update;
}
ctail(m);
c->mcp = m;
unlock(&cache);
return;
}
}
/* LRU the cache headers */
m = cache.head;
if(!canqlock(m))
goto Busy;
l = &cache.hash[m->qid.path%NHASH];
for(f = *l; f; f = f->hash) {
if(f == m) {
*l = m->hash;
break;
}
l = &f->hash;
}
m->qid = c->qid;
m->dev = c->dev;
m->type = c->type;
l = &cache.hash[h];
m->hash = *l;
*l = m;
Update:
ctail(m);
c->mcp = m;
unlock(&cache);
cnodata(m);
qunlock(m);
return;
Busy:
unlock(&cache);
c->mcp = 0;
}
void
copen(Chan *c)
{
int h;
Extent *e, *next;
Mntcache *m, *f, **l;
/* directories aren't cacheable and append-only files confuse us */
if(c->qid.type&(QTDIR|QTAPPEND))
return;
h = c->qid.path%NHASH;
qlock(&cache);
for(m = cache.hash[h]; m; m = m->hash) {
if(m->qid.path == c->qid.path)
if(m->qid.type == c->qid.type)
if(m->dev == c->dev && m->type == c->type) {
c->mcp = m;
ctail(m);
qunlock(&cache);
/* File was updated, invalidate cache */
if(m->qid.vers != c->qid.vers) {
m->qid.vers = c->qid.vers;
qlock(m);
cnodata(m);
qunlock(m);
}
return;
}
}
/* LRU the cache headers */
m = cache.head;
l = &cache.hash[m->qid.path%NHASH];
for(f = *l; f; f = f->hash) {
if(f == m) {
*l = m->hash;
break;
}
l = &f->hash;
}
m->qid = c->qid;
m->dev = c->dev;
m->type = c->type;
l = &cache.hash[h];
m->hash = *l;
*l = m;
ctail(m);
qlock(m);
c->mcp = m;
e = m->list;
m->list = 0;
qunlock(&cache);
while(e) {
next = e->next;
extentfree(e);
e = next;
}
qunlock(m);
}