[PATCH] gendisk fixes

 - fixes an idiocy with floppy_find() et.al. - they forgot to set
   *part to 0.  As the result, open() on anything other than fd0 had
   lead to interesting effects...

 - fixes off-by-1 in set_disk_ro().

drivers/acorn/block/fd1772.c

@@ -1528,6 +1528,7 @@ static struct gendisk *floppy_find(dev_t dev, int *part, void *data)
 	int drive = *part & 3;
 	if ((*part >> 2) > NUM_DISK_TYPES || drive >= FD_MAX_UNITS)
 		return NULL;
+	*part = 0;
 	return get_disk(disks[drive]);
 }
 

drivers/block/amiflop.c

@@ -1765,6 +1765,7 @@ static struct gendisk *floppy_find(dev_t dev, int *part, void *data)
 	int drive = *part & 3;
 	if (unit[drive].type->code == FD_NODRIVE)
 		return NULL;
+	*part = 0;
 	return get_disk(unit[drive].gendisk);
 }
 

drivers/block/ataflop.c

@@ -1919,6 +1919,7 @@ static struct gendisk *floppy_find(dev_t dev, int *part, void *data)
 	int type  = *part >> 2;
 	if (drive >= FD_MAX_UNITS || type > NUM_DISK_MINORS)
 		return NULL;
+	*part = 0;
 	return get_disk(unit[drive].disk);
 }
 

drivers/block/floppy.c

@@ -4210,6 +4210,7 @@ static struct gendisk *floppy_find(dev_t dev, int *part, void *data)
 	    !(allowed_drive_mask & (1 << drive)) ||
 	    fdc_state[FDC(drive)].version == FDC_NONE)
 		return NULL;
+	*part = 0;
 	return get_disk(disks[drive]);
 }
 

drivers/block/genhd.c

@@ -92,9 +92,7 @@ EXPORT_SYMBOL(blk_unregister_region);
 
 static struct gendisk *exact_match(dev_t dev, int *part, void *data)
 {
-	struct gendisk *p = data;
-	*part = MINOR(dev) - p->first_minor;
-	return p;
+	return data;
 }
 
 static int exact_lock(dev_t dev, void *data)
@@ -363,7 +361,7 @@ void set_disk_ro(struct gendisk *disk, int flag)
 {
 	int i;
 	disk->policy = flag;
-	for (i = 0; i < disk->minors; i++)
+	for (i = 0; i < disk->minors - 1; i++)
 		disk->part[i].policy = flag;
 }
 

drivers/ide/ide-probe.c

@@ -982,7 +982,7 @@ static int ata_lock(dev_t dev, void *data)
 struct gendisk *ata_probe(dev_t dev, int *part, void *data)
 {
 	ide_hwif_t *hwif = data;
-	int unit = MINOR(dev) >> PARTN_BITS;
+	int unit = *part >> PARTN_BITS;
 	ide_drive_t *drive = &hwif->drives[unit];
 	if (!drive->present)
 		return NULL;
@@ -1000,6 +1000,7 @@ struct gendisk *ata_probe(dev_t dev, int *part, void *data)
 	}
 	if (!drive->driver)
 		return NULL;
+	*part &= (1 << PARTN_BITS) - 1;
 	return get_disk(drive->disk);
 }