diff options
| -rw-r--r-- | sys/lib/acid/kernel | 36 | ||||
| -rw-r--r-- | sys/src/9/port/cache.c | 131 |
2 files changed, 100 insertions, 67 deletions
diff --git a/sys/lib/acid/kernel b/sys/lib/acid/kernel index 68c484b5d..7d082ec12 100644 --- a/sys/lib/acid/kernel +++ b/sys/lib/acid/kernel @@ -74,6 +74,20 @@ defn chans() { } } +defn findchan(dev,type,path) { + local c; + + c = (Chan)chanalloc.list; + while c != 0 do { + if c.ref != 0 then { + if c.dev == dev && c.type == type && c.qid.path == path then + return c; + } + c=(Chan)c.link; + } + return 0; +} + defn nchans() { local c, n; @@ -159,6 +173,27 @@ defn badchans() { } } +NHASH=128; +defn mntcache() { + local i, m, c; + + i=0; loop 1,NHASH do { + m = cache.hash[i]; + while m != 0 do { + complex Mntcache m; + print(m\X, " dev ", m.dev\D, " type ", m.type, " qid (", + m.qid.path, " ", m.qid.vers\D, ")\n"); + c = findchan(m.dev, m.type, m.qid.path); + if c != 0 then { + print(" "); + chan(c); + } + m = m.hash; + } + i = i+1; + } +} + // manipulate processes defn proctab(x) { return procalloc.arena+sizeofProc*x; @@ -379,5 +414,6 @@ if (map()[2]) != {} then { // map has more than two elements -> active proc needacid("proc"); needacid("chan"); needacid("segment"); + needacid("cache"); } } diff --git a/sys/src/9/port/cache.c b/sys/src/9/port/cache.c index 3bef6d4e9..e748c7301 100644 --- a/sys/src/9/port/cache.c +++ b/sys/src/9/port/cache.c @@ -208,39 +208,42 @@ ctail(Mntcache *m) } } +/* called with cache locked */ +static Mntcache* +clookup(Chan *c, int skipvers) +{ + Mntcache *m; + + for(m = cache.hash[c->qid.path%NHASH]; m; m = m->hash) + if(eqchantdqid(c, m->type, m->dev, m->qid, skipvers) && c->qid.type == m->qid.type) + return m; + + return 0; +} + 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)) + if(c->qid.type&(QTDIR|QTAPPEND)){ + c->mcp = 0; 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; - } + m = clookup(c, 1); + if(m == 0) + m = cache.head; + else if(m->qid.vers == c->qid.vers) { + ctail(m); + unlock(&cache); + c->mcp = m; + return; } + ctail(m); - /* 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) { @@ -250,39 +253,53 @@ copen(Chan *c) l = &f->hash; } + if(!canqlock(m)){ + unlock(&cache); + qlock(m); + lock(&cache); + f = clookup(c, 0); + if(f != 0) { + /* + * someone got there first while cache lock + * was released and added a updated Mntcache + * for us. update LRU and use it. + */ + ctail(f); + unlock(&cache); + qunlock(m); + c->mcp = f; + return; + } + } + m->qid = c->qid; m->dev = c->dev; m->type = c->type; - l = &cache.hash[h]; + l = &cache.hash[c->qid.path%NHASH]; m->hash = *l; *l = m; -Update: - ctail(m); - c->mcp = m; unlock(&cache); cnodata(m); qunlock(m); - return; -Busy: - unlock(&cache); - c->mcp = 0; + c->mcp = m; } -static int -cdev(Mntcache *m, Chan *c) +/* return locked Mntcache if still valid else reset mcp */ +static Mntcache* +ccache(Chan *c) { - if(m->qid.path != c->qid.path) - return 0; - if(m->qid.type != c->qid.type) - return 0; - if(m->dev != c->dev) - return 0; - if(m->type != c->type) - return 0; - if(m->qid.vers != c->qid.vers) - return 0; - return 1; + Mntcache *m; + + m = c->mcp; + if(m) { + qlock(m); + if(eqchantdqid(c, m->type, m->dev, m->qid, 0) && c->qid.type == m->qid.type) + return m; + c->mcp = 0; + qunlock(m); + } + return 0; } int @@ -298,17 +315,10 @@ cread(Chan *c, uchar *buf, int len, vlong off) if(off+len > maxcache) return 0; - m = c->mcp; + m = ccache(c); if(m == 0) return 0; - qlock(m); - if(cdev(m, c) == 0) { - qunlock(m); - c->mcp = 0; - return 0; - } - offset = off; t = &m->list; for(e = *t; e; e = e->next) { @@ -470,15 +480,9 @@ cupdate(Chan *c, uchar *buf, int len, vlong off) if(off > maxcache || len == 0) return; - m = c->mcp; + m = ccache(c); if(m == 0) return; - qlock(m); - if(cdev(m, c) == 0) { - qunlock(m); - c->mcp = 0; - return; - } /* * Find the insertion point @@ -564,17 +568,10 @@ cwrite(Chan* c, uchar *buf, int len, vlong off) if(off > maxcache || len == 0) return; - m = c->mcp; + m = ccache(c); if(m == 0) return; - qlock(m); - if(cdev(m, c) == 0) { - qunlock(m); - c->mcp = 0; - return; - } - offset = off; m->qid.vers++; c->qid.vers++; |