shithub: gefs

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fs: adjust ordering of sync to survive crashes in all cases

--- a/blk.c

+++ b/blk.c

@@ -751,8 +751,14 @@

 			xh = bp.hash;

 			ck = b->bp.hash;

 		}

-		if(ck != xh)

-			broke("%s: %ullx %llux != %llux", Ecorrupt, bp.addr, xh, ck);

+		if(ck != xh){

+			if(flg & GBsoftchk){

+				fprint(2, "%s: %ullx %llux != %llux", Ecorrupt, bp.addr, xh, ck);

+				error(Ecorrupt);

+			}else{

+				broke("%s: %ullx %llux != %llux", Ecorrupt, bp.addr, xh, ck);

+			}

+		}

 	}

 	b->bp.gen = bp.gen;

 	b->lasthold = getcallerpc(&bp);

--- a/dat.h

+++ b/dat.h

@@ -267,6 +267,7 @@

 	GBraw	= 1<<0,

 	GBwrite	= 1<<1,

 	GBnochk	= 1<<2,

+	GBsoftchk = 1<<3,

 };

 enum {

--- a/fs.c

+++ b/fs.c

@@ -87,9 +87,19 @@

          */

 	qlock(&fs->mutlk);

 	tracem("packb");

-	dlsync();

 	for(mnt = agetp(&fs->mounts); mnt != nil; mnt = mnt->next)

 		updatesnap(&mnt->root, mnt->root, mnt->name);

+	/*

+	 * Now that we've updated the snaps, we can sync the

+	 * dlist; the snap tree will not change from here.

+	 */

+	dlsync();

+	dl = fs->snapdl;

+	fs->snapdl.hd = Zb;

+	fs->snapdl.tl = Zb;

+	fs->snapdl.ins = nil;

+	traceb("syncdl.dl", dl.hd);

+	traceb("syncdl.rb", fs->snap.bp);

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

 		a = &fs->arenas[i];

 		qlock(a);

@@ -112,16 +122,13 @@

 		fs->arenabp[i] = a->h0->bp;

 		qunlock(a);

 	}

-

+	assert(fs->snapdl.hd.addr == -1);

+	traceb("packsb.rb", fs->snap.bp);

 	packsb(fs->sb0->buf, Blksz, fs);

 	packsb(fs->sb1->buf, Blksz, fs);

 	finalize(fs->sb0);

 	finalize(fs->sb1);

 	fs->snap.dirty = 0;

-	dl = fs->snapdl;

-	fs->snapdl.hd = Zb;

-	fs->snapdl.tl = Zb;

-	fs->snapdl.ins = nil;

 	qunlock(&fs->mutlk);

 	/*

@@ -159,18 +166,11 @@

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

 	 */

 	tracem("snapdl");

-	freedl(&dl, 1);

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

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

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

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

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

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

-	fs->snapdl.ins = nil;

 	wrbarrier();

 	qunlock(&fs->mutlk);

 	qunlock(&fs->synclk);

 	tracem("synced");

+	freedl(&dl, 1);

 	poperror();

 }

--- a/load.c

+++ b/load.c

@@ -27,13 +27,13 @@

 	h0 = nil;

 	h1 = nil;

 	if(!waserror()){

-		h0 = getblk(bp, 0);

+		h0 = getblk(bp, GBsoftchk);

 		poperror();

 	}else

 		print("loading arena primary header: %s\n", errmsg());

 	bp.addr += Blksz;

 	if(!waserror()){

-		h1 = getblk(bp, 0);

+		h1 = getblk(bp, GBsoftchk);

 		poperror();

 	}else

 		print("loading arena backup header: %s\n", errmsg());