shithub: gefs

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snap: fix snapshotting bugs

--- a/blk.c

+++ b/blk.c

@@ -794,7 +794,7 @@

 		return nil;

 	if((b = cachepluck()) == nil)

 		return nil;

-	initblk(b, bp, t->gen, ty);

+	initblk(b, bp, t->memgen, ty);

 	b->alloced = getcallerpc(&t);

 	return b;

 }

@@ -944,7 +944,7 @@

 	Bfree *f;

 	ulong ge;

-	if(t != nil && t != &fs->snap && bp.gen <= t->prev){

+	if(t != nil && t != &fs->snap && bp.gen <= t->gen){

 		killblk(t, bp);

 		return;

 	}

--- a/dat.h

+++ b/dat.h

@@ -404,6 +404,7 @@

 	int	nlbl;	/* number of labels referring to us */

 	int	ht;	/* height of the tree */

 	Bptr	bp;	/* block pointer of root */

+	vlong	memgen;	/* wip next generation */

 	vlong	gen;	/* generation */

 	vlong	prev;	/* previous snapshot */

--- a/snap.c

+++ b/snap.c

@@ -62,7 +62,7 @@

 	uint h;

 	h = ihash(gen) ^ ihash(bgen);

-	for(dl = fs->dlcache[h %fs->dlcmax]; dl != nil; dl = dl->chain)

+	for(dl = fs->dlcache[h % fs->dlcmax]; dl != nil; dl = dl->chain)

 		if(dl->gen == gen && dl->bgen == bgen)

 			break;

 	if(dl != nil)

@@ -127,11 +127,8 @@

 	Dlist *dt;

 	dlcachedel(dl, 0);

-	dl->cprev = nil;

-	dl->cnext = fs->dlhead;

-	fs->dlhead = dl;

-	while(fs->ctail != nil && fs->dlcount >= fs->dlcmax){

+	while(fs->dltail != nil && fs->dlcount >= fs->dlcmax){

 		dt = fs->dltail;

 		dlsync(dt);

 		dlcachedel(dt, 1);

@@ -138,12 +135,20 @@

 		dropblk(dt->ins);

 		free(dt);

 	}

+

+	dl->cprev = nil;

+	dl->cnext = fs->dlhead;

+	if(fs->dltail == nil)

+		fs->dltail = dl;

+	if(fs->dlhead != nil)

+		fs->dlhead->cprev = dl;

+	fs->dlhead = dl;

 }

 static char*

 freedl(Dlist *dl, int docontents)

 {

-	Bptr bp;

+	Bptr bp, fb;

 	Blk *b;

 	char *p;

@@ -154,10 +159,10 @@

 			return Efs;

 		if(docontents){

 			for(p = b->data; p != b->data+b->deadsz; p += 8){

-				if(blkdealloc(UNPACK64(p)) == -1){

-					dropblk(b);

-					return Efs;

-				}

+				fb.addr = UNPACK64(p);

+				fb.hash = -1;

+				fb.gen = -1;

+				freeblk(nil, nil, fb);

 			}

 		}

 		bp = b->deadp;

@@ -407,11 +412,9 @@

 	t->nsucc = 0;

 	t->ht = o->ht;

 	t->bp = o->bp;

-	if(o->nlbl == 0 && o->nsucc == 1)

-		t->prev = o->prev;

-	else

-		t->prev = o->gen;

-	t->gen = aincv(&fs->nextgen, 1);

+	t->prev = o->gen;

+	t->gen = o->memgen;

+	t->memgen = aincv(&fs->nextgen, 1);

 	m[1].op = Oinsert;

 	tree2kv(t, &m[1], buf[1], sizeof(buf[1]));

@@ -428,8 +431,10 @@

 	o->dirty = 0;

 	/* this was the last ref to the snap */

-	if(o->nlbl == 0 && o->nsucc == 1)

+	if(o->nlbl == 0 && o->nsucc == 1){

+		t->prev = o->prev;

 		delsnap(o, t->gen, nil);

+	}

 	closesnap(o);

 	*r = t;

 	return nil;

@@ -469,6 +474,7 @@

 	if(unpacktree(t, kv.v, kv.nv) == nil)

 		abort();

 	t->memref = 1;

+	t->memgen = aincv(&fs->nextgen, 1);

 	return t;

 Error:

 	free(t);

@@ -491,6 +497,7 @@

 		abort();

 	f->op = DFtree;

 	f->t = t;

+print("limbo %#p\n", t);

 	ge = agetl(&fs->epoch);

 	f->next = fs->limbo[ge];

 	fs->limbo[ge] = f;

@@ -537,7 +544,7 @@

 	if((dl = getdl(t->gen, bp.gen)) == nil)

 		return -1;

-	if(dl->ins == nil || dl->ins->deadsz == Dlspc){

+	if(dl->ins == nil || Dlspc - dl->ins->deadsz < 8){

 		if((b = newblk(&fs->snap, Tdlist)) == nil){

 			putdl(dl);

 			return -1;

@@ -552,6 +559,7 @@

 			dl->tl = b->bp;

 			b->deadp = (Bptr){-1, -1, -1};

 		}

+		cacheins(b);

 		dl->hd = b->bp;

 		dl->ins = b;

 	}