1993/1013/port/cache.c (diff list | history)

1993/1011/sys/src/9/port/cache.c:6,31 – 1993/1013/sys/src/9/port/cache.c:6,274 (short | long | prev | next)
1993/1011		#include "../port/error.h" #include "devtab.h" typedef struct Fcache Fcache; typedef struct Fcalloc Fcalloc; struct Fcache
1993/1013		Image fscache; typedef Extent Extent; struct Extent
1993/1011		{ QLock;
1993/1013		int bid; ulong start; int len; Extent *next; }; typedef struct Mntcache Mntcache; struct Mntcache {
1993/1011		Qid; Page* alloc; Fcache* hash; Fcache* next;
1993/1013		int dev; int type; Qlock; Extent *list; Mntcache *hash; Mntcache *prev; Mntcache *next;
1993/1011		}; struct Fcalloc
1993/1013		typedef struct Cache Cache; struct Cache
1993/1011		{ ulong start; short len; Page* data;
1993/1013		Ref; Mntcache *head; Mntcache *tail; Mntcache *hash[NHASH];
1993/1011		};
1993/1013		Cache cache;
1993/1011		Fcache* clook(Qid *qid)
1993/1013		Mntcache* clook(Chan *c)
1993/1011		{
1993/1013		int h;
1993/1011
1993/1013		h = c->qid.path%NHASH; lock(&cache); for(m = cache.hash[h]; m; m = m->hash) { if(m->path == c->path) { qlock(m); if(m->path == c->qid.path) if(m->dev == c->dev) if(m->type == c->type) { unlock(&cache); return m; } qunlock(m); } } unlock(&cache); return 0; } void cnodata(Mntcache *m) { Extent *e, *n; /* * Invalidate all extent data * Image lru will waste the pages */ for(e = m->list; e; e = n) { n = e->list; free(e); } } void ctail(Mntcache *m) { lock(&cache); /* Unlink and send to the tail */ if(m->prev) m->prev->next = m->next; else cache.head = m->next; if(m->next) m->next->prev = m->prev; else cache.tail = m->prev; if(cache.tail) { m->prev = cache.tail; cache.tail->next = m; m->next = 0; cache.tail = m; } else { cache.head = cache.tail = m; m->prev = m->next = 0; } unlock(&cache); } void copen(Chan *c) { Mntcache *m, *f, **l; m = clook(c); if(m != 0) { /* File was updated */ if(m->vers != c->vers) cnodata(m); ctail(m); qunlock(m); return; } /* LRU the cache headers */ m = cache.head; qlock(m); lock(cache); l = &cache.hash[m->qid.path%NHASH]; for(f = *l; f; f = f->next) { if(f == m) { *l = f->next; break; } l = &f->next; } l = &cache.hash[c->qid.path%NHASH]; m->hash = *l; *l = m; unlock(cache); m->qid = c->qid; m->dev = c->dev; m->type = c->type; cnodata(m); ctail(m); c->mcp = m; qunlock(m); } static int cdev(Mntcache *m, Chan *c) { if(m->path != c->path) return 0; if(m->vers != c->vers) return 0; if(m->dev != c->dev) return 0; if(m->type != c->type) return 0; return 1; } int cread(Chan *c, uchar *buf, int len, long offset) { KMap *k; Page *p; Mntcache *m; Extent *e, **l; int o, l, total; m = c->mcp; if(m == 0) return 0; qlock(m); if(cdev(m, c) == 0) { qunlock(m); return 0; } end = offset+len; l = &m->list; for(e = *l; e; e = e->next) { if(e->start >= offset && e->start+e->len < end) break; l = &e->next; } if(e == 0) { qunlock(m); return 0; } total = 0; while(len) { p = lookpage(&fscache, e->bid); if(p == 0) { *l = e->next; free(e); qunlock(m); return total; } k = kmap(p); if(waserror()) { kunmap(k); putpage(p); qunlock(m); nexterror(); } o = offset - e->start; l = len; if(l > e->len-o) l = e->len-o; p = (uchar*)VA(k) + o; memset(buf, p, l); kunmap(k); putpage(p); buf += l; len -= l; offset += l; total += l; l = &e->next; e = e->next; if(e == 0 || e->start != offset) break; } qunlock(m) return total; } void cwrite(Chan *c, uchar *buf, int len, long offset) { Extent *e; Mntcache *m; if(offset > MAXCACHE) return; m = c->mcp; if(m == 0) return; qlock(m); if(cdev(m, c) == 0) { qunlock(m); return; } if(m->list == 0) { e = malloc(sizeof(Extent)); if(e == 0) return; e->start = offset; l = len; if(l > BY2PG) l = BY2PG; p = auxpage(); if(p == 0) return; e->bid = incref(&cache); p->daddr = e->bid; cachepage(p, fscache); k = kmap(p); kunmap(p); }
1993/1011		}