shithub: gefs

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blk: make flags atomic

this simplifies the code and removes a lock
that we don't care about.

--- a/blk.c

+++ b/blk.c

@@ -19,6 +19,32 @@

 QLock blklock;

+void

+setflag(Blk *b, int flg)

+{

+	long ov, nv;

+

+	while(1){

+		ov = b->flag;

+		nv = ov | flg;

+		if(cas(&b->flag, ov, nv))

+			break;

+	}

+}

+

+void

+clrflag(Blk *b, int flg)

+{

+	long ov, nv;

+

+	while(1){

+		ov = b->flag;

+		nv = ov & ~flg;

+		if(cas(&b->flag, ov, nv))

+			break;

+	}

+}

+

 Blk*

 readblk(vlong bp, int flg)

 {

@@ -39,7 +65,6 @@

 		off += n;

 		rem -= n;

 	}

-	memset(&b->Lock, 0, sizeof(Lock));

 	b->type = (flg&GBraw) ? Traw : GBIT16(b->buf+0);

 	b->bp.addr = bp;

 	b->bp.hash = -1;

@@ -278,7 +303,7 @@

 	Oplog *l;

 	int i;

-fprint(2, "deadlisted %B [%p::%B]\n", bp, t, t->bp);

+dprint("deadlisted %B [%p::%B]\n", bp, t, t->bp);

 //fprint(2, "predeadlist\n");

 //showtreeroot(2, t);

 //fprint(2, "----\n");

@@ -453,8 +478,8 @@

 		return -1;

 	if((b = mallocz(sizeof(Blk), 1)) == nil)

 		return -1;

+	setflag(b, Bdirty);

 	b->type = Tlog;

-	b->flag = Bdirty;

 	b->bp.addr = bp;

 	b->ref = 1;

 	b->data = b->buf + Hdrsz;

@@ -681,7 +706,7 @@

 	b->data = b->buf + Hdrsz;

 	b->fnext = nil;

-	b->flag = Bdirty;

+	setflag(b, Bdirty);

 	b->nval = 0;

 	b->valsz = 0;

 	b->nbuf = 0;

@@ -713,9 +738,7 @@

 	assert(b->type == Tsuper);

 	p = b->data;

-	lock(b);

-	b->flag |= Bdirty;

-	unlock(b);

+	setflag(b, Bdirty);

 	memcpy(p, "gefs0001", 8); p += 8;

 	PBIT32(p, 0); p += 4; /* dirty */

 	PBIT32(p, Blksz); p += 4;

@@ -736,8 +759,7 @@

 {

 	vlong h;

-	lock(b);

-	b->flag |= Bfinal;

+	setflag(b, Bfinal);

 	if(b->type != Traw)

 		PBIT16(b->buf, b->type);

 	switch(b->type){

@@ -769,7 +791,6 @@

 	case Tarena:

 		break;

 	}

-	unlock(b);

 }

 Blk*

@@ -867,10 +888,8 @@

 void

 freeblk(Tree *t, Blk *b)

 {

-	lock(b);

-	assert((b->flag & Bqueued) == 0);

+	assert(!(b->flag & Bqueued));

 	b->freed = getcallerpc(&b);

-	unlock(b);

 	freebp(t, b->bp);

 }

--- a/cache.c

+++ b/cache.c

@@ -40,7 +40,7 @@

 		fs->chead = b->cnext;

 	b->cnext = nil;

 	b->cprev = nil;

-	b->flag &= ~Bcached;

+	clrflag(b, Bcached);

 	fs->ccount--;

 }

@@ -82,10 +82,8 @@

 	b->cnext = fs->chead;

 	b->cprev = nil;

 	fs->chead = b;

-	if((b->flag&Bcached) == 0){

-		lock(b);

-		b->flag |= Bcached;

-		unlock(b);

+	if((b->flag & Bcached) == 0){

+		setflag(b, Bcached);

 		fs->ccount++;

 		refblk(b);

 	}

--- a/dat.h

+++ b/dat.h

@@ -535,8 +535,6 @@

 };

 struct Blk {

-	Lock;

-

 	/* cache entry */

 	Blk	*cnext;

 	Blk	*cprev;

@@ -545,7 +543,7 @@

 	/* Freelist entry */

 	Blk	*fnext;

-	short	flag;

+	long	flag;

 	/* serialized to disk in header */

 	short	type;	/* @0, for all */

--- a/fns.h

+++ b/fns.h

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

 void	btdone(Scan*);

 void	setflag(Blk *b, int);

-int	chkflag(Blk *b, int);

+void	clrflag(Blk *b, int);

 char*	estrdup(char*);

@@ -137,4 +137,4 @@

 /* it's in libc... */

 extern int cas(long*, long, long);

 extern int cas64(u64int*, u64int, u64int);

-uvlong	inc64(uvlong*, uvlong);

\ No newline at end of file

+uvlong	inc64(uvlong*, uvlong);

--- a/pack.c

+++ b/pack.c

@@ -362,9 +362,7 @@

 		tlhash = -1;

 		if(t->dead[i].tail != nil){

 			tl = t->dead[i].tail;

-			lock(tl);

 			assert(tl->flag & Bfinal);

-			unlock(tl);

 			tladdr = tl->bp.addr;

 			tlhash = tl->bp.hash;

 		}

--- a/ream.c

+++ b/ream.c

@@ -101,7 +101,7 @@

 	b->bp.addr = addr;

 	b->logsz = 32;

 	b->data = b->buf + Hdrsz;

-	b->flag |= Bdirty;

+	setflag(b, Bdirty);

 	p = b->data+Loghdsz;

 	PBIT64(p+ 0, addr|LogFree);		/* addr */

--- a/snap.c

+++ b/snap.c

@@ -23,9 +23,7 @@

 syncblk(Blk *b)

 {

 	assert(b->flag & Bfinal);

-	lock(b);

-	b->flag &= ~(Bqueued|Bdirty);

-	unlock(b);

+	clrflag(b, Bqueued|Bdirty);

 	return pwrite(fs->fd, b->buf, Blksz, b->bp.addr);

 }

@@ -32,7 +30,7 @@

 void

 enqueue(Blk *b)

 {

-	assert(b->flag&Bdirty);

+	assert(b->flag & Bdirty);

 	finalize(b);

 	if(syncblk(b) == -1){

 		ainc(&fs->broken);

@@ -199,7 +197,7 @@

 void

 freedead(Bptr bp, void *)

 {

-	fprint(2, "reclaimed deadlist: %B\n", bp);

+	dprint("reclaimed deadlist: %B\n", bp);

 	reclaimblk(bp);

 }