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gefs: protect fids with rwlock

--- a/sys/src/cmd/gefs/dat.h

+++ b/sys/src/cmd/gefs/dat.h

@@ -676,7 +676,7 @@

 };

 struct Fid {

-	Lock;

+	RWLock;

 	Fid	*next;

 	/*

 	 * if opened with OEXEC, we want to use a snapshot,

--- a/sys/src/cmd/gefs/fs.c

+++ b/sys/src/cmd/gefs/fs.c

@@ -741,6 +741,7 @@

 		return nil;

 	*n = *f;

+	memset(&n->RWLock, 0, sizeof(RWLock));

 	n->fid = new;

 	n->ref = 2; /* one for dup, one for clunk */

 	n->mode = -1;

@@ -780,7 +781,7 @@

 	Fid *f, **pf;

 	u32int h;

-	assert(!canlock(fid));

+	assert(!canwlock(fid));

 	h = ihash(fid->fid) % Nfidtab;

 	lock(&c->fidtablk[h]);

@@ -823,6 +824,21 @@

 	}

 }

+static void

+freeamsg(Amsg *a)

+{

+	if(a == nil)

+		return;

+	switch(a->op){

+	case AOrclose:

+	case AOclear:

+		clunkdent(a->mnt, a->dent);

+		clunkmount(a->mnt);

+		break;

+	}

+	free(a);

+}

+

 static int

 readmsg(Conn *c, Fmsg **pm)

 {

@@ -1253,7 +1269,7 @@

 fswalk(Fmsg *m)

 {

 	char *name, kbuf[Maxent], kvbuf[Kvmax];

-	int duid, dgid, dmode;

+	int duid, dgid, dmode, duped;

 	vlong up, upup, prev;

 	Dent *dent, *dir;

 	Fid *o, *f;

@@ -1270,8 +1286,10 @@

 		rerror(m, Enofid);

 		return;

 	}

+	rlock(o);

 	if(waserror()){

 		rerror(m, errmsg());

+		runlock(o);

 		putfid(o);

 		return;

 	}

@@ -1325,25 +1343,22 @@

 	if(i == 0 && m->nwname != 0)

 		error(Esrch);

 	f = o;

+	duped = 0;

 	if(m->fid != m->newfid && i == m->nwname){

 		if((f = dupfid(m->conn, m->newfid, o)) == nil)

 			error(Efid);

-		putfid(o);

-		poperror();

-		if(waserror()){

-			rerror(m, errmsg());

-			putfid(f);

-			return;

-		}

+		duped = 1;

 	}

+	runlock(o);

+

 	if(i > 0 && i == m->nwname){

-		lock(f);

+		wlock(f);

 		ao = nil;

 		if(waserror()){

-			if(f != o)

+			if(duped)

 				clunkfid(m->conn, f, &ao);

 			assert(ao == nil);

-			unlock(f);

+			wunlock(f);

 			nexterror();

 		}

 		if(up == -1ULL){

@@ -1374,10 +1389,12 @@

 		f->dgid = dgid;

 		f->dmode = dmode;

 		poperror();

-		unlock(f);

+		wunlock(f);

 	}

-	respond(m, &r);

+	if(duped)

+		putfid(o);

 	putfid(f);

+	respond(m, &r);

 	poperror();

 }

@@ -1439,7 +1456,7 @@

 	wlock(de);

 	if(waserror()){

 		rerror(m, errmsg());

-		free(*ao);

+		freeamsg(*ao);

 		*ao = nil;

 		goto Err;

 	}

@@ -1638,9 +1655,9 @@

 		rerror(m, Enofid);

 		return;

 	}

-	lock(f);

+	wlock(f);

 	clunkfid(m->conn, f, ao);

-	unlock(f);

+	wunlock(f);

 	r.type = Rclunk;

 	respond(m, &r);

 	putfid(f);

@@ -1671,7 +1688,7 @@

 		rerror(m, Enofid);

 		return;

 	}

-	lock(f);

+	wlock(f);

 	if(waserror()){

 		rerror(m, errmsg());

@@ -1761,7 +1778,7 @@

 	r.iounit = f->iounit;

 	respond(m, &r);

 Out:	poperror();

-Err:	unlock(f);

+Err:	wunlock(f);

 	putfid(f);

 	return;

 }

@@ -1805,15 +1822,13 @@

 	}

 	t = f->mnt->root;

 	nm = 0;

-	lock(f);

+	wlock(f);

 	clunkfid(m->conn, f, ao);

-	unlock(f);

-

 	truncwait(f->dent, id);

 	wlock(f->dent);

 	if(waserror()){

 		rerror(m, errmsg());

-		free(*ao);

+		freeamsg(*ao);

 		*ao = nil;

 		goto Err;

 	}

@@ -1834,7 +1849,10 @@

 		error(e);

 	if(fsaccess(f, f->dmode, f->duid, f->dgid, DMWRITE) == -1)

 		error(Eperm);

-	lock(f);

+

+	freeamsg(*ao);

+	*ao = nil;

+

 	mb[nm].op = Odelete;

 	mb[nm].k = f->dent->k;

 	mb[nm].nk = f->dent->nk;

@@ -1841,8 +1859,6 @@

 	mb[nm].v = "\0";

 	mb[nm].nv = 1;

 	nm++;

-	unlock(f);

-

 	if(f->dent->qid.type & QTDIR){

 		packsuper(buf, sizeof(buf), f->qpath);

 		mb[nm].op = Oclobber;

@@ -1851,8 +1867,7 @@

 		mb[nm].nv = 0;

 		nm++;

 	}else{

-		if(*ao == nil)

-			*ao = emalloc(sizeof(Amsg), 1);

+		*ao = emalloc(sizeof(Amsg), 1);

 		ainc(&f->mnt->ref);

 		(*ao)->op = AOclear;

 		(*ao)->mnt = f->mnt;

@@ -1870,6 +1885,7 @@

 	poperror();

 Err:

 	wunlock(f->dent);

+	wunlock(f);

 	putfid(f);

 	return;

 }

@@ -1928,9 +1944,9 @@

 	r.qid = d.qid;

 	r.iounit = f->iounit;

-	lock(f);

+	wlock(f);

 	if(f->mode != -1){

-		unlock(f);

+		wunlock(f);

 		error(Einuse);

 	}

 	if((m->mode & OTRUNC) && !(f->dent->mode & DMAPPEND)){

@@ -1938,7 +1954,7 @@

 		if(waserror()){

 			wunlock(f->dent);

-			free(*ao);

+			freeamsg(*ao);

 			*ao = nil;

 			nexterror();

 		}

@@ -1976,7 +1992,7 @@

 	f->mode = mode2bits(m->mode);

 	if(m->mode & ORCLOSE)

 		f->rclose = emalloc(sizeof(Amsg), 1);

-	unlock(f);

+	wunlock(f);

 	poperror();

 	respond(m, &r);

 	putfid(f);

@@ -1990,6 +2006,12 @@

 	Scan *s;

 	Xdir d;

+	/* mutates scan */

+	wlock(f);

+	if(waserror()){

+		wunlock(f);

+		nexterror();

+	}

 	s = f->scan;

 	if(s != nil && s->offset != 0 && s->offset != m->offset)

 		error(Edscan);

@@ -1997,12 +2019,10 @@

 		s = emalloc(sizeof(Scan), 1);

 		pfx[0] = Klabel;

 		btnewscan(s, pfx, 1);

-		lock(f);

 		if(f->scan != nil){

 			free(f->scan);

 		}

 		f->scan = s;

-		unlock(f);

 	}

 	if(s->donescan){

 		r->count = 0;

@@ -2038,6 +2058,8 @@

 		n -= ns;

 	}

 	btexit(s);

+	poperror();

+	wunlock(f);

 	r->count = p - r->data;

 	return;

 }

@@ -2050,6 +2072,12 @@

 	Tree *t;

 	Scan *s;

+	/* mutates scan */

+	wlock(f);

+	if(waserror()){

+		wunlock(f);

+		nexterror();

+	}

 	s = f->scan;

 	t = agetp(&f->mnt->root);

 	if(s != nil && s->offset != 0 && s->offset != m->offset)

@@ -2058,22 +2086,21 @@

 		s = emalloc(sizeof(Scan), 1);

 		packdkey(pfx, sizeof(pfx), f->qpath, nil);

 		btnewscan(s, pfx, sizeof(pfx));

-		lock(f);

 		if(f->scan != nil)

 			free(f->scan);

 		f->scan = s;

-		unlock(f);

 	}

 	if(s->donescan){

 		r->count = 0;

-		return;

+		goto Out;

 	}

 	p = r->data;

 	n = m->count;

 	if(s->overflow){

+		/* someone picked an iounit too small for a dir */

 		if((ns = kv2statbuf(&s->kv, p, n)) == -1){

 			r->count = 0;

-			return;

+			error(Ebotch);

 		}

 		s->overflow = 0;

 		p += ns;

@@ -2090,8 +2117,11 @@

 		p += ns;

 		n -= ns;

 	}

-	btexit(s);

 	r->count = p - r->data;

+	btexit(s);

+Out:

+	poperror();

+	wunlock(f);

 }

 static void

@@ -2102,10 +2132,12 @@

 	Dent *e;

 	Tree *t;

+	rlock(f);

 	e = f->dent;

 	rlock(e);

 	if(m->offset > e->length){

 		runlock(e);

+		runlock(f);

 		return;

 	}

 	p = r->data;

@@ -2124,6 +2156,7 @@

 		c -= n;

 	}

 	runlock(e);

+	runlock(f);

 }

 static void

@@ -2177,19 +2210,18 @@

 		rerror(m, Enofid);

 		return;

 	}

-	if(!(f->mode & DMWRITE)){

-		rerror(m, Einuse);

-		putfid(f);

-		return;

-	}

+	wlock(f);

 	truncwait(f->dent, id);

 	wlock(f->dent);

 	if(waserror()){

 		rerror(m, errmsg());

 		wunlock(f->dent);

+		wunlock(f);

 		putfid(f);

 		return;

 	}

+	if(!(f->mode & DMWRITE))

+		error(Einuse);

 	if(f->dent->gone)

 		error(Ephase);

 	if(f->dent->qid.type & QTAUTH){

@@ -2255,6 +2287,7 @@

 	poperror();

  	respond(m, &r);

 	wunlock(f->dent);

+	wunlock(f);

 	putfid(f);	

 }

@@ -2328,9 +2361,9 @@

 			ainc(&f->ref);

 			unlock(&c->fidtablk[i]);

-			lock(f);

+			wlock(f);

 			clunkfid(c, f, &a);

-			unlock(f);

+			wunlock(f);

 			putfid(f);

 			if(a != nil)

@@ -2441,15 +2474,11 @@

 					rerror(m, Enofid);

 					continue;

 				}

-				lock(f);

+				wlock(f);

 				clunkfid(m->conn, f, &a);

-				unlock(f);

+				wunlock(f);

 				putfid(f);

-				if(a != nil){

-					clunkdent(a->mnt, a->dent);

-					clunkmount(a->mnt);

-					free(a);

-				}

+				freeamsg(a);

 			}

 			rerror(m, Erdonly);

 			continue;

@@ -2736,15 +2765,13 @@

 				am->dent->trunc = 0;

 				rwakeup(&am->dent->truncrz);

 				qunlock(&am->dent->trunclk);

-				clunkdent(am->mnt, am->dent);

 			}

-			clunkmount(am->mnt);

 			poperror();

 			break;

 		}

 Next:

 		assert(estacksz() == 0);

-		free(am);

+		freeamsg(am);

 	}

 }

-- 

⑨