shithub: gefs

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fs, blk: hold mutlk when cleaning epoch, pull tree out of mnt to prevent version skew

--- a/fs.c

+++ b/fs.c

@@ -118,13 +118,12 @@

 	finalize(fs->sb1);

 	fs->snap.dirty = 0;

 	qunlock(&fs->mutlk);

-	wrbarrier();

 	/*

 	 * pass 1: sync block headers; if we crash here,

 	 *  the block footers are consistent, and we can

 	 *  use them.

-	 */	wrbarrier();

+	 */

 	for(i = 0; i < fs->narena; i++)

 		enqueue(fs->arenas[i].h0);

 	wrbarrier();

@@ -136,6 +135,7 @@

 	 * get synced after so that we can use them next

 	 * time around.

          */

+	qlock(&fs->mutlk);

 	syncblk(fs->sb0);

 	syncblk(fs->sb1);

@@ -146,12 +146,10 @@

          */

 	for(i = 0; i < fs->narena; i++)

 		enqueue(fs->arenas[i].h1);

-	wrbarrier();

 	/*

 	 * Pass 4: clean up the old snap tree's deadlist

 	 */

-	qlock(&fs->mutlk);

 	freedl(&fs->snapdl, 1);

 	fs->snapdl.hd.addr = -1;

 	fs->snapdl.hd.hash = -1;

@@ -160,8 +158,8 @@

 	fs->snapdl.tl.hash = -1;

 	fs->snapdl.tl.gen = -1;

 	fs->snapdl.ins = nil;

-	qunlock(&fs->mutlk);

 	wrbarrier();

+	qunlock(&fs->mutlk);

 	qunlock(&fs->synclk);

 	poperror();

 }

@@ -368,17 +366,6 @@

 }

-static int

-lookup(Mount *mnt, Key *k, Kvp *kv, char *buf, int nbuf)

-{

-	Tree *r;

-

-	if(mnt == nil)

-		error(Eattach);

-	r = agetp(&mnt->root);

-	return btlookup(r, k, kv, buf, nbuf);

-}

-

 static void

 upsert(Mount *mnt, Msg *m, int nm)

 {

@@ -410,7 +397,7 @@

 }

 static int

-readb(Fid *f, char *d, vlong o, vlong n, vlong sz)

+readb(Tree *t, Fid *f, char *d, vlong o, vlong n, vlong sz)

 {

 	char buf[17], kvbuf[17+32];

 	vlong fb, fo;

@@ -433,7 +420,7 @@

 	PACK64(k.k+1, f->qpath);

 	PACK64(k.k+9, fb);

-	if(!lookup(f->mnt, &k, &kv, kvbuf, sizeof(kvbuf))){

+	if(!btlookup(t, &k, &kv, kvbuf, sizeof(kvbuf))){

 		memset(d, 0, n);

 		return n;

 	}

@@ -451,6 +438,7 @@

 	char buf[Kvmax];

 	vlong fb, fo;

 	Blk *b, *t;

+	Tree *r;

 	Bptr bp;

 	Kvp kv;

@@ -463,7 +451,8 @@

 	b = newblk(f->mnt->root, Tdat, f->qpath);

 	t = nil;

-	if(lookup(f->mnt, m, &kv, buf, sizeof(buf))){

+	r = f->mnt->root;

+	if(btlookup(r, m, &kv, buf, sizeof(buf))){

 		bp = unpackbp(kv.v, kv.nv);

 		if(fb < sz && (fo != 0 || n != Blksz)){

 			t = getblk(bp, GBraw);

@@ -470,7 +459,7 @@

 			memcpy(b->buf, t->buf, Blksz);

 			dropblk(t);

 		}

-		freeblk(f->mnt->root, nil, bp);

+		freeblk(r, nil, bp);

 	}

 	if(fo+n > Blksz)

 		n = Blksz-fo;

@@ -1134,7 +1123,7 @@

 }

 static int

-findparent(Fid *f, vlong *qpath, char **name, char *buf, int nbuf)

+findparent(Tree *t, Fid *f, vlong *qpath, char **name, char *buf, int nbuf)

 {

 	char *p, kbuf[Keymax];

 	Kvp kv;

@@ -1143,7 +1132,7 @@

 	p = packsuper(kbuf, sizeof(kbuf), f->pqpath);

 	k.k = kbuf;

 	k.nk = p - kbuf;

-	if(!lookup(f->mnt, &k, &kv, buf, nbuf))

+	if(!btlookup(t, &k, &kv, buf, nbuf))

 		return 0;

 	*name = unpackdkey(kv.v, kv.nv, qpath);

 	return 1;

@@ -1158,6 +1147,7 @@

 	Fid *o, *f;

 	Dent *dent;

 	Mount *mnt;

+	Tree *t;

 	Fcall r;

 	Xdir d;

 	Kvp kv;

@@ -1175,6 +1165,7 @@

 	}

 	if(o->mode != -1)

 		error(Einuse);

+	t = o->mnt->root;

 	mnt = o->mnt;

 	up = o->qpath;

 	prev = o->qpath;

@@ -1208,7 +1199,7 @@

 					dmode = d.mode;

 					goto Found;

 				}

-				if(!findparent(o, &prev, &name, kbuf, sizeof(kbuf)))

+				if(!findparent(t, o, &prev, &name, kbuf, sizeof(kbuf)))

 					error(Esrch);

 			}

 			p = packdkey(kbuf, sizeof(kbuf), prev, name);

@@ -1218,7 +1209,7 @@

 		dmode = d.mode;

 		k.k = kbuf;

 		k.nk = p - kbuf;

-		if(!lookup(mnt, &k, &kv, kvbuf, sizeof(kvbuf)))

+		if(!btlookup(t, &k, &kv, kvbuf, sizeof(kvbuf)))

 			break;

 		kv2dir(&kv, &d);

 Found:

@@ -1730,6 +1721,7 @@

 {

 	char *p, buf[Kvmax];

 	int mbits;

+	Tree *t;

 	Fcall r;

 	Xdir d;

 	Fid *f;

@@ -1746,10 +1738,11 @@

 		putfid(f);

 		return;

 	}

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

 	if((f->qpath & Qdump) != 0){

 		filldumpdir(&d);

 	}else{

-		if(!lookup(f->mnt, f->dent, &kv, buf, sizeof(buf)))

+		if(!btlookup(t, f->dent, &kv, buf, sizeof(buf)))

 			error(Esrch);

 		kv2dir(&kv, &d);

 	}

@@ -1936,6 +1929,7 @@

 	vlong n, c, o;

 	char *p;

 	Dent *e;

+	Tree *t;

 	e = f->dent;

 	rlock(e);

@@ -1946,10 +1940,11 @@

 	p = r->data;

 	c = m->count;

 	o = m->offset;

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

 	if(m->offset + m->count > e->length)

 		c = e->length - m->offset;

 	while(c != 0){

-		n = readb(f, p, o, c, e->length);

+		n = readb(t, f, p, o, c, e->length);

 		r->count += n;

 		if(n == 0)

 			break;

@@ -2233,8 +2228,8 @@

 		}

 		assert(estacksz() == 0);

 		epochend(id);

- 		qunlock(&fs->mutlk);

 		epochclean();

+ 		qunlock(&fs->mutlk);

 		if(a != nil)

 			chsend(fs->admchan, a);

@@ -2275,7 +2270,9 @@

 			getval(b, i, &kv);

 			bp = unpackbp(kv.v, kv.nv);

 			freetree(bp, pred);

+			qlock(&fs->mutlk);

 			epochclean();

+			qunlock(&fs->mutlk);

 		}

 	}

 	if(rb.gen > pred)

@@ -2289,6 +2286,10 @@

  * has already waited for an epoch to tick over, there's

  * nobody that can be accessing the tree other than us,

  * and we just need to keep the limbo list short.

+ *

+ * Because this is the last reference to the tree, we don't

+ * need to hold the mutlk, other than when we free or kill

+ * blocks via epochclean.

  */

 void

 sweeptree(Tree *t)

@@ -2296,7 +2297,6 @@

 	char pfx[1];

 	Scan s;

 	Bptr bp;

-

 	pfx[0] = Kdat;

 	btnewscan(&s, pfx, 1);

 	btenter(t, &s);

@@ -2306,7 +2306,9 @@

 		bp = unpackbp(s.kv.v, s.kv.nv);

 		if(bp.gen > t->pred)

 			freeblk(nil, nil, bp);

+		qlock(&fs->mutlk);

 		epochclean();

+		qunlock(&fs->mutlk);

 	}

 	btexit(&s);

 	freetree(t->bp, t->pred);

@@ -2438,8 +2440,8 @@

 				m.nv = 0;

 				upsert(am->mnt, &m, 1);

 				epochend(id);

-				qunlock(&fs->mutlk);

 				epochclean();

+				qunlock(&fs->mutlk);

 				poperror();

 			}

 			if(am->dent != nil){

--- a/load.c

+++ b/load.c

@@ -85,7 +85,6 @@

 		sysfatal("open %s: %r", dev);

 	if((d = dirfstat(fs->fd)) == nil)

 		sysfatal("stat %s: %r", dev);

-

 	eb = d->length;

 	eb = eb - (eb%Blksz) - Blksz;

 	bhd = (Bptr){0, -1, -1};