1993/1015/port/cache.c (diff list | history)

port/cache.c on 1993/1011
1993/1011		#include "u.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "../port/error.h" #include "devtab.h"
1993/1013		Image fscache;
1993/1014		enum { NHASH = 128, MAXCACHE = 1024*1024, NFILE = 4096, }; typedef struct Extent Extent;
1993/1013		struct Extent
1993/1011		{
1993/1013		int bid; ulong start; int len;
1993/1014		Page *cache;
1993/1013		Extent *next; }; typedef struct Mntcache Mntcache; struct Mntcache {
1993/1011		Qid;
1993/1013		int dev; int type;
1993/1014		QLock;
1993/1013		Extent *list; Mntcache *hash; Mntcache *prev; Mntcache *next;
1993/1011		};
1993/1013		typedef struct Cache Cache; struct Cache
1993/1011		{
1993/1013		Ref; Mntcache *head; Mntcache *tail; Mntcache *hash[NHASH];
1993/1011		};
1993/1013		Cache cache;
1993/1011
1993/1014		void cinit(void) { int i; Mntcache *m; cache.ref = 1; cache.head = xalloc(sizeof(Mntcache)*NFILE); m = cache.head;
1993/1015		for(i = 0; i < NFILE; i++) {
1993/1014		m->next = m+1; m->prev = m-1; m++; } cache.tail = m; cache.tail->next = 0; cache.head->prev = 0; }
1993/1013		Mntcache* clook(Chan *c)
1993/1011		{
1993/1013		int h;
1993/1014		Mntcache *m;
1993/1011
1993/1013		h = c->qid.path%NHASH; lock(&cache); for(m = cache.hash[h]; m; m = m->hash) {
1993/1014		if(m->path == c->qid.path) {
1993/1013		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
1993/1015		cprint(Mntcache *m, char *s)
1993/1014		{ Extent *e;
1993/1015		return; print("%s: 0x%lux.0x%lux %d %d\n", s, m->path, m->vers, m->type, m->dev);
1993/1014
1993/1015		for(e = m->list; e; e = e->next)
1993/1014		print("\t%4d %5d %4d %lux\n", e->bid, e->start, e->len, e->cache); } Page* cpage(Extent *e) { /* Easy consistency check */ if(e->cache->daddr != e->bid) return 0; return lookpage(&fscache, e->bid); } void
1993/1013		cnodata(Mntcache *m) { Extent *e, *n; /* * Invalidate all extent data * Image lru will waste the pages */ for(e = m->list; e; e = n) {
1993/1014		n = e->next;
1993/1013		free(e); }
1993/1015		m->list = 0;
1993/1013		} void
1993/1015		ctail(Mntcache *m, int dolock)
1993/1013		{
1993/1015		if(dolock) lock(&cache);
1993/1013		/* 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; }
1993/1015		if(dolock) unlock(&cache);
1993/1013		} void copen(Chan *c) { Mntcache *m, *f, **l;
1993/1015		if(c->qid.path & CHDIR) return;
1993/1013		m = clook(c); if(m != 0) {
1993/1015		c->mcp = m; ctail(m, 1);
1993/1013		/* File was updated */
1993/1015		if(m->vers != c->qid.vers) { cprint(m, "copen mod");
1993/1013		cnodata(m);
1993/1015		m->vers = c->qid.vers; }
1993/1013		qunlock(m);
1993/1015		cprint(m, "copen lru");
1993/1013		return; } /* LRU the cache headers */ m = cache.head; qlock(m);
1993/1014		lock(&cache); l = &cache.hash[m->path%NHASH];
1993/1013		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;
1993/1015		ctail(m, 0);
1993/1014		unlock(&cache);
1993/1015
1993/1014		m->Qid = c->qid;
1993/1013		m->dev = c->dev; m->type = c->type; cnodata(m); c->mcp = m; qunlock(m);
1993/1015		cprint(m, "copen new");
1993/1013		} static int cdev(Mntcache *m, Chan *c) {
1993/1014		if(m->path != c->qid.path)
1993/1013		return 0;
1993/1014		if(m->vers != c->qid.vers)
1993/1013		return 0; if(m->dev != c->dev) return 0; if(m->type != c->type) return 0; return 1; } int
1993/1014		cread(Chan *c, uchar *buf, int len, ulong offset)
1993/1013		{ KMap *k; Page *p; Mntcache *m;
1993/1014		Extent *e, **t; int o, l, total, end;
1993/1013
1993/1015		if(c->qid.path & CHDIR) return 0;
1993/1013		m = c->mcp; if(m == 0) return 0;
1993/1015
1993/1013		qlock(m); if(cdev(m, c) == 0) { qunlock(m); return 0; } end = offset+len;
1993/1014		t = &m->list; for(e = *t; e; e = e->next) {
1993/1013		if(e->start >= offset && e->start+e->len < end) break;
1993/1014		t = &e->next;
1993/1013		} if(e == 0) { qunlock(m); return 0; } total = 0; while(len) {
1993/1014		p = cpage(e);
1993/1013		if(p == 0) {
1993/1014		*t = e->next;
1993/1013		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;
1993/1014		memmove(buf, (uchar*)VA(k) + o, l);
1993/1013		kunmap(k); putpage(p); buf += l; len -= l; offset += l; total += l;
1993/1014		t = &e->next;
1993/1013		e = e->next; if(e == 0 || e->start != offset) break; }
1993/1014		qunlock(m);
1993/1013		return total; }
1993/1014		Extent* cchain(uchar *buf, ulong offset, int len, Extent **tail) { int l; Page *p; KMap *k; Extent *e, *start, **t; start = 0; t = &start; while(len) { e = malloc(sizeof(Extent)); if(e == 0) break; p = auxpage(); if(p == 0) { free(e); break; } l = len; if(l > BY2PG) l = BY2PG;
1993/1015		e->cache = p; e->start = offset; e->len = l;
1993/1014		e->bid = incref(&cache); p->daddr = e->bid; k = kmap(p); memmove((void*)VA(k), buf, l); kunmap(k); cachepage(p, &fscache); putpage(p); buf += l; offset += l; len -= l; *t = e; *tail = e; t = &e->next; } return start; } int cpgmove(Extent *e, uchar *buf, int boff, int len) { Page *p; KMap *k; p = cpage(e); if(p == 0) return 0;
1993/1015
1993/1014		k = kmap(p); memmove((uchar*)VA(k)+boff, buf, len); kunmap(k); putpage(p); return 1; }
1993/1013		void
1993/1014		cupdate(Chan *c, uchar *buf, int len, ulong offset)
1993/1013		{ Mntcache *m;
1993/1014		Extent *tail; Extent *e, *f, *p;
1993/1015		int o, ee, eblock;
1993/1013
1993/1015		if(c->qid.path & CHDIR)
1993/1013		return;
1993/1015		if(offset > MAXCACHE || len == 0) return;
1993/1013		m = c->mcp; if(m == 0) return; qlock(m); if(cdev(m, c) == 0) { qunlock(m); return; }
1993/1014		/* * Find the insertion point */ p = 0; for(f = m->list; f; f = f->next) { if(f->start >= offset) break; p = f; }
1993/1015
1993/1014		if(p == 0) { /* at the head */ eblock = offset+len; /* trim if there is a successor */ if(f != 0 && eblock >= f->start) { len -= (eblock - f->start); if(len <= 0) { qunlock(m); return; } } e = cchain(buf, offset, len, &tail); m->list = e; if(tail != 0) tail->next = f; qunlock(m); return; } /* trim to the predecessor */ ee = p->start+p->len; if(offset < ee) { o = ee - offset; len -= o; if(len <= 0) { qunlock(m);
1993/1013		return;
1993/1014		} buf += o; offset += o; } /* try and pack data into the predecessor */ if(offset == ee && p->len < BY2PG) { o = len; if(o > BY2PG - p->len) o = BY2PG - p->len; if(len <= 0) { qunlock(m);
1993/1013		return;
1993/1014		}
1993/1015		if(cpgmove(p, buf, p->len, o)) { p->len += o;
1993/1014		buf += o; len -= o; offset += o; if(len <= 0) { qunlock(m); return; } }
1993/1013		}
1993/1014		/* append to extent list */ if(f == 0) { p->next = cchain(buf, offset, len, &tail); qunlock(m); return; } /* trim data against successor */ eblock = offset+len; if(eblock > f->start) { o = eblock - f->start; if(o < 0) { qunlock(m); return; } len -= o; }
1993/1015		/* insert a middle block */
1993/1014		p->next = cchain(buf, offset, len, &tail); if(p->next == 0) p->next = f; else tail->next = f; qunlock(m);
1993/1015		} void cwrite(Chan* c, uchar *buf, int len, ulong offset) { int o; Mntcache *m; ulong eblock, ee; Extent *p, *f, *e, *tail; if(offset > MAXCACHE || len == 0) return; m = c->mcp; if(m == 0) return; qlock(m); if(cdev(m, c) == 0) { qunlock(m); return; } m->vers++; p = 0; for(f = m->list; f; f = f->next) { if(offset >= f->start) break; p = f; } if(p != 0) { ee = p->start+p->len; if(ee > offset) { o = ee - offset; p->len -= o; if(p->len) panic("del empty extent"); } } eblock = offset+len; /* free the overlap - its a rare case */ while(f && f->start < eblock) { e = f->next; free(f); f = e; } e = cchain(buf, offset, len, &tail); if(p == 0) m->list = e; else p->next = e; if(tail != 0) tail->next = f; qunlock(m); cprint(m, "cwrite");
1993/1011		}