Fix dumpfs kernel.

case 1:
	IDE0=primary=disk
	IDE1=primary=disk
	IDE1=secondary=disk

	filsys main ch0f{h2h3}
	-> panic: ataxfer: sdunits[3].subno is 0, not 1

case 2:
	install SATA-RAID cards. this card has 4port 2controllers.
	card1=ctlr0=port0=disk
	card1=ctlr1=port0=disk
	card2=ctlr0=port0=disk

	auto detect:
		ata h4 ...
		ata h4 ...
		ata h4 ...

	all h4?

	filsys main ch4f{h6h8}
	-> panic: ataxfer: sdunits[4].dev=$p1 is wrong controller (want $p2)

Notes:
Sat May 5 17:47:18 EDT 2007 geoff
    The first case should be fixed; the second is a problem
    because we've defined ide device names to be either
    h<ctlr>.<drive> or h<number> where <number> is <ctlr>*2+<drive>,
    so more than two drives per controller won't work.
    It's also not obvious to me how one would address more
    than two drives when talking to the controller.

Reference: /n/sources/patch/sorry/fs-ata
Date: Sat May  5 16:25:47 CES 2007
Signed-off-by: lufia1@gmail.com
Reviewed-by: geoff

--- /sys/src/fs/pc/sdata.c	Sat May  5 16:09:56 2007
+++ /sys/src/fs/pc/sdata.c	Sat May  5 16:09:47 2007
@@ -778,15 +778,13 @@
 }
 
 static Drive*
-atagetdrive(int cmdport, int ctlport, int dev)
+atagetdrive(int cmdport, int ctlport, int dev, int driveno)
 {
 	Drive *drive;
-	int as, i, pkt, driveno;
+	int as, i, pkt;
 	uchar buf[512], *p;
 	ushort iconfig, *sp;
 
-	driveno = (cmdport == Ctlr0cmd? 0:
-		cmdport == Ctlr1cmd? NCtlrdrv: 2*NCtlrdrv);
 	if (dev == Dev1)
 		driveno++;
 
@@ -1026,7 +1024,7 @@
 	 * If the one drive found is Dev0 and the EDD command
 	 * didn't indicate Dev1 doesn't exist, check for it.
 	 */
-	if((drive = atagetdrive(cmdport, ctlport, dev)) == nil)
+	if((drive = atagetdrive(cmdport, ctlport, dev, drivenum)) == nil)
 		goto release;
 	if((ctlr = malloc(sizeof(Ctlr))) == nil){
 		free(drive);
@@ -1039,6 +1037,7 @@
 		goto release;
 	}
 	memset(sdev, 0, sizeof(SDev));
+	sdev->index = drivenum;
 	drive->ctlr = ctlr;
 
 	atactlr[drivenum/NCtlrdrv] = ctlr;
@@ -1055,7 +1054,7 @@
 			 * Ataprobe is the only place possibly invalid
 			 * drives should be selected.
 			 */
-			drive = atagetdrive(cmdport, ctlport, Dev1);
+			drive = atagetdrive(cmdport, ctlport, Dev1, drivenum-1);
 			if(drive != nil){
 				drive->ctlr = ctlr;
 				ctlr->drive[1] = drive;
@@ -2533,7 +2532,7 @@
 		i = sdpp - sdevs;
 		sdp->ifc = &sdataifc;
 		sdp->nunit = NCtlrdrv;
-		sdp->index = i;
+		//sdp->index = i;
 		sdp->idno = 'C' + i;
 		sdp->ctlr = atactlr[i];
 		if (sdp->ctlr != nil)