dossrv: Implement support for != 512 sector and track sizes

The iotrack buffer layer always assumed 512 byte sector
size and 9 sectors per track.

To support 4K sector size fats, make the iotrack code
deal with it.

Instead of the fixed size Track structure, we just allocate
the pointers and buffers dynamically, and move the sector
size and tack size in the Xfs structure.

Tracks can still be reused between differnet file-systems
after a purgetrack().

The initial fat header has to be read with devread()
instead of getsect() to determine the sector/track size
of the file-system.

1 files changed, 95 insertions, 79 deletions

diff --git a/sys/src/cmd/dossrv/iotrack.c b/sys/src/cmd/dossrv/iotrack.c
index 6081a5509..f1833ae56 100644
--- a/sys/src/cmd/dossrv/iotrack.c
+++ b/sys/src/cmd/dossrv/iotrack.c
@@ -4,6 +4,9 @@
 #include "dat.h"
 #include "fns.h"
 
+static MLock	freelock;
+static Iosect *	freelist;
+
 #define	HIOB		31	/* a prime */
 #define	NIOBUF		80
 
@@ -19,6 +22,10 @@ static Iotrack	iobuf[NIOBUF];		/* the real ones */
 
 #define	TOFRONT(h, p)	((h)->next  != (p) && (UNLINK(p, next, prev), LINK(h,p, next, prev)))
 
+static Iotrack *getiotrack(Xfs*, vlong);
+static Iosect *getiosect(Xfs*, vlong, int);
+static void purgetrack(Iotrack*);
+
 Iosect *
 getsect(Xfs *xf, vlong addr)
 {
@@ -31,19 +38,21 @@ getosect(Xfs *xf, vlong addr)
 	return getiosect(xf, addr, 0);
 }
 
-Iosect *
+static Iosect *
 getiosect(Xfs *xf, vlong addr, int rflag)
 {
-	Iotrack *t;
 	vlong taddr;
 	int toff;
+	Iotrack *t;
 	Iosect *p;
 
 	if(addr < 0)
 		return nil;
-	toff = addr % Sect2trk;
+	toff = addr % xf->sect2trk;
 	taddr = addr - toff;
 	t = getiotrack(xf, taddr);
+	if(t == nil)
+		return nil;
 	if(rflag && (t->flags&BSTALE)){
 		if(tread(t) < 0){
 			unmlock(&t->lock);
@@ -51,16 +60,31 @@ getiosect(Xfs *xf, vlong addr, int rflag)
 		}
 		t->flags &= ~BSTALE;
 	}
-	t->ref++;
-	p = t->tp->p[toff];
-	if(p == 0){
-		p = newsect();
-		t->tp->p[toff] = p;
+	p = t->tp[toff];
+	if(p == nil){
+		mlock(&freelock);
+		p = freelist;
+		if(p != nil)
+			freelist = p->next;
+		else {
+			p = malloc(sizeof(Iosect));
+			if(p == nil) {
+				unmlock(&freelock);
+				unmlock(&t->lock);
+				return nil;
+			}
+		}
+		p->next = nil;
+		unmlock(&freelock);
+
 		p->flags = t->flags&BSTALE;
 		p->lock.key = 0;
+		p->iobuf = ((uchar*)&t->tp[xf->sect2trk]) + toff*xf->sectsize;
 		p->t = t;
-		p->iobuf = t->tp->buf[toff];
+
+		t->tp[toff] = p;
 	}
+	t->ref++;
 	unmlock(&t->lock);
 	mlock(&p->lock);
 	return p;
@@ -87,7 +111,7 @@ putsect(Iosect *p)
 	unmlock(&p->lock);
 }
 
-Iotrack *
+static Iotrack *
 getiotrack(Xfs *xf, vlong addr)
 {
 	Iotrack *hp, *p;
@@ -142,8 +166,14 @@ loop:
 		goto loop;
 	}
 	purgetrack(p);
-	p->addr = addr;
+	p->tp = malloc(xf->sect2trk*sizeof(Iosect*) + xf->sect2trk*xf->sectsize);
+	if(p->tp == nil){
+		unmlock(&p->lock);
+		return nil;
+	}
+	memset(p->tp, 0, xf->sect2trk*sizeof(Iosect*));
 	p->xf = xf;
+	p->addr = addr;
 	p->flags = BSTALE;
 out:
 	mlock(&hp->lock);
@@ -155,39 +185,55 @@ out:
 	return p;
 }
 
-void
+static void
 purgetrack(Iotrack *t)
 {
-	int i, ref = Sect2trk;
-	Iosect *p;
-
-	for(i=0; i<Sect2trk; i++){
-		p = t->tp->p[i];
-		if(p == 0){
-			--ref;
-			continue;
-		}
-		if(canmlock(&p->lock)){
-			freesect(p);
-			--ref;
-			t->tp->p[i] = 0;
+	if(t->tp != nil){
+		Xfs *xf = t->xf;
+		int i, ref = xf->sect2trk;
+
+		for(i=0; i<xf->sect2trk; i++){
+			Iosect *p = t->tp[i];
+			if(p == nil){
+				--ref;
+				continue;
+			}
+			if(canmlock(&p->lock)){
+				t->tp[i] = nil;
+
+				mlock(&freelock);
+				p->next = freelist;
+				freelist = p;
+				unmlock(&freelock);
+				--ref;
+			}
 		}
+		if(t->ref != ref)
+			panic("purgetrack");
+		if(ref != 0)
+			return;
+
+		free(t->tp);
 	}
-	if(t->ref != ref)
-		panic("purgetrack");
+	assert(t->ref == 0);
+	t->tp = nil;
+	t->xf = nil;
+	t->addr = -1;
+	t->flags = 0;
 }
 
 int
 twrite(Iotrack *t)
 {
-	int i, ref;
+	Xfs *xf = t->xf;
 
-	chat("[twrite %lld...", t->addr);
+	chat("[twrite %lld+%lld...", t->addr, xf->offset);
 	if(t->flags & BSTALE){
-		for(ref=0,i=0; i<Sect2trk; i++)
-			if(t->tp->p[i])
+		int i, ref = 0;
+		for(i=0; i<xf->sect2trk; i++)
+			if(t->tp[i] != nil)
 				++ref;
-		if(ref < Sect2trk){
+		if(ref < xf->sect2trk){
 			if(tread(t) < 0){
 				chat("error]");
 				return -1;
@@ -195,7 +241,7 @@ twrite(Iotrack *t)
 		}else
 			t->flags &= ~BSTALE;
 	}
-	if(devwrite(t->xf, t->addr, t->tp->buf, Trksize) < 0){
+	if(devwrite(xf, t->addr, (uchar*)&t->tp[xf->sect2trk], xf->sect2trk*xf->sectsize) < 0){
 		chat("error]");
 		return -1;
 	}
@@ -206,33 +252,31 @@ twrite(Iotrack *t)
 int
 tread(Iotrack *t)
 {
+	Xfs *xf = t->xf;
 	int i, ref = 0;
-	uchar buf[Sect2trk][Sectorsize];
 
-	for(i=0; i<Sect2trk; i++)
-		if(t->tp->p[i])
+	chat("[tread %lld+%lld...", t->addr, xf->offset);
+	for(i=0; i<xf->sect2trk; i++)
+		if(t->tp[i] != nil)
 			++ref;
-	chat("[tread %lld+%lld...", t->addr, t->xf->offset);
 	if(ref == 0){
-		if(devread(t->xf, t->addr, t->tp->buf, Trksize) < 0){
+		if(devread(xf, t->addr, (uchar*)&t->tp[xf->sect2trk], xf->sect2trk*xf->sectsize) < 0){
 			chat("error]");
 			return -1;
 		}
-		chat("done]");
-		t->flags &= ~BSTALE;
-		return 0;
-	}
-	if(devread(t->xf, t->addr, buf, Trksize) < 0){
-		chat("error]");
-		return -1;
-	}
-	for(i=0; i<Sect2trk; i++)
-		if(t->tp->p[i] == 0){
-			memmove(t->tp->buf[i], buf[i], Sectorsize);
+	} else {
+		for(i=0; i<xf->sect2trk; i++){
+			if(t->tp[i] != nil)
+				continue;
+			if(devread(xf, t->addr + i, ((uchar*)&t->tp[xf->sect2trk]) + i*xf->sectsize, xf->sectsize) < 0){
+				chat("error]");
+				return -1;
+			}
 			chat("%d ", i);
 		}
-	chat("done]");
+	}
 	t->flags &= ~BSTALE;
+	chat("done]");
 	return 0;
 }
 
@@ -285,34 +329,6 @@ iotrack_init(void)
 		p->hprev = p->hnext = p;
 		p->prev = p->next = p;
 		TOFRONT(mp, p);
-		p->tp = sbrk(sizeof(Track));
-		memset(p->tp->p, 0, sizeof p->tp->p);
+		purgetrack(p);
 	}
 }
-
-static MLock	freelock;
-static Iosect *	freelist;
-
-Iosect *
-newsect(void)
-{
-	Iosect *p;
-
-	mlock(&freelock);
-	if(p = freelist)	/* assign = */
-		freelist = p->next;
-	else
-		p = malloc(sizeof(Iosect));
-	unmlock(&freelock);
-	p->next = 0;
-	return p;
-}
-
-void
-freesect(Iosect *p)
-{
-	mlock(&freelock);
-	p->next = freelist;
-	freelist = p;
-	unmlock(&freelock);
-}