diff --git a/stand/common/dev_net.c b/stand/common/dev_net.c
--- a/stand/common/dev_net.c
+++ b/stand/common/dev_net.c
@@ -77,7 +77,7 @@
 static int netdev_opens;
 
 static int	net_init(void);
-static int	net_open(struct open_file *, ...);
+static int	net_open(struct open_file *);
 static int	net_close(struct open_file *);
 static void	net_cleanup(void);
 static int	net_strategy(void *, int, daddr_t, size_t, char *, size_t *);
@@ -115,21 +115,16 @@
 /*
  * Called by devopen after it sets f->f_dev to our devsw entry.
  * This opens the low-level device and sets dev->d_opendata.
- * This is declared with variable arguments...
  */
 static int
-net_open(struct open_file *f, ...)
+net_open(struct open_file *f)
 {
-	struct iodesc *d;
-	va_list args;
 	struct devdesc *dev;
+	struct iodesc *d;
 	const char *devname;	/* Device part of file name (or NULL). */
 	int error = 0;
 
-	va_start(args, f);
-	dev = va_arg(args, struct devdesc *);
-	va_end(args);
-
+	dev = f->f_devdata;
 	devname = dev->d_dev->dv_name;
 	/* Before opening another interface, close the previous one first. */
 	if (netdev_sock >= 0 && strcmp(devname, netdev_name) != 0)
diff --git a/stand/common/devopen.c b/stand/common/devopen.c
--- a/stand/common/devopen.c
+++ b/stand/common/devopen.c
@@ -49,7 +49,7 @@
 	/* point to device-specific data so that device open can use it */
 	f->f_dev = dev->d_dev;
 	f->f_devdata = dev;
-	result = dev->d_dev->dv_open(f, dev);
+	result = dev->d_dev->dv_open(f);
 	if (result != 0) {
 		f->f_devdata = NULL;
 		f->f_dev = NULL;
diff --git a/stand/common/disk.c b/stand/common/disk.c
--- a/stand/common/disk.c
+++ b/stand/common/disk.c
@@ -236,6 +236,10 @@
 	struct ptable_entry part;
 	int rc, slice, partition;
 
+	/*
+	 * XXX Audit callers, see if we have anything shifty going on or if we
+	 * can properly assert here that dev->dd.d_dev->dv_type == DEVT_DISK.
+	 */
 	if (sectorsize == 0) {
 		DPRINTF("unknown sector size");
 		return (ENXIO);
diff --git a/stand/common/md.c b/stand/common/md.c
--- a/stand/common/md.c
+++ b/stand/common/md.c
@@ -61,7 +61,7 @@
 /* devsw I/F */
 static int md_init(void);
 static int md_strategy(void *, int, daddr_t, size_t, char *, size_t *);
-static int md_open(struct open_file *, ...);
+static int md_open(struct open_file *);
 static int md_close(struct open_file *);
 static int md_print(int);
 
@@ -121,15 +121,11 @@
 }
 
 static int
-md_open(struct open_file *f, ...)
+md_open(struct open_file *f)
 {
-	va_list ap;
 	struct devdesc *dev;
 
-	va_start(ap, f);
-	dev = va_arg(ap, struct devdesc *);
-	va_end(ap);
-
+	dev = f->f_devdata;
 	if (dev->d_unit != 0)
 		return (ENXIO);
 
diff --git a/stand/common/vdisk.c b/stand/common/vdisk.c
--- a/stand/common/vdisk.c
+++ b/stand/common/vdisk.c
@@ -38,7 +38,7 @@
 
 static int vdisk_init(void);
 static int vdisk_strategy(void *, int, daddr_t, size_t, char *, size_t *);
-static int vdisk_open(struct open_file *, ...);
+static int vdisk_open(struct open_file *);
 static int vdisk_close(struct open_file *);
 static int vdisk_ioctl(struct open_file *, u_long, void *);
 static int vdisk_print(int);
@@ -292,24 +292,20 @@
 }
 
 static int
-vdisk_open(struct open_file *f, ...)
+vdisk_open(struct open_file *f)
 {
-	va_list args;
-	struct disk_devdesc *dev;
+	struct devdesc *dev;
 	vdisk_info_t *vd;
 	int rc = 0;
 
-	va_start(args, f);
-	dev = va_arg(args, struct disk_devdesc *);
-	va_end(args);
-	if (dev == NULL)
-		return (EINVAL);
-	vd = vdisk_get_info((struct devdesc *)dev);
+	dev = f->f_devdata;
+	vd = vdisk_get_info(dev);
 	if (vd == NULL)
 		return (EINVAL);
 
-	if (dev->dd.d_dev->dv_type == DEVT_DISK) {
-		rc = disk_open(dev, vd->vdisk_size, vd->vdisk_sectorsz);
+	if (dev->d_dev->dv_type == DEVT_DISK) {
+		rc = disk_open((struct disk_devdesc *)dev, vd->vdisk_size,
+		    vd->vdisk_sectorsz);
 	}
 	if (rc == 0)
 		vd->vdisk_open++;
diff --git a/stand/efi/libefi/efihttp.c b/stand/efi/libefi/efihttp.c
--- a/stand/efi/libefi/efihttp.c
+++ b/stand/efi/libefi/efihttp.c
@@ -58,7 +58,7 @@
 static int efihttp_dev_init(void);
 static int efihttp_dev_strategy(void *devdata, int rw, daddr_t blk, size_t size,
     char *buf, size_t *rsize);
-static int efihttp_dev_open(struct open_file *f, ...);
+static int efihttp_dev_open(struct open_file *f);
 static int efihttp_dev_close(struct open_file *f);
 
 static int efihttp_fs_open(const char *path, struct open_file *f);
@@ -228,8 +228,9 @@
 }
 
 static int
-efihttp_dev_open(struct open_file *f, ...)
+efihttp_dev_open(struct open_file *f)
 {
+	struct devdesc *dev;
 	EFI_HTTP_CONFIG_DATA config;
 	EFI_HTTPv4_ACCESS_POINT config_access;
 	DNS_DEVICE_PATH *dns;
@@ -238,13 +239,13 @@
 	IPv4_DEVICE_PATH *ipv4;
 	MAC_ADDR_DEVICE_PATH *mac;
 	URI_DEVICE_PATH *uri;
-	struct devdesc *dev;
 	struct open_efihttp *oh;
 	char *c;
 	EFI_HANDLE handle;
 	EFI_STATUS status;
 	int err, len;
 
+	dev = f->f_devdata;
 	if (!efihttp_init_done)
 		return (ENXIO);
 
@@ -292,7 +293,6 @@
 	if (!oh)
 		return (ENOMEM);
 	oh->dev_handle = handle;
-	dev = (struct devdesc *)f->f_devdata;
 	dev->d_opendata = oh;
 
 	status = BS->OpenProtocol(handle, &httpsb_guid, (void **)&sb, IH, NULL,
diff --git a/stand/efi/libefi/efipart.c b/stand/efi/libefi/efipart.c
--- a/stand/efi/libefi/efipart.c
+++ b/stand/efi/libefi/efipart.c
@@ -53,7 +53,7 @@
 static int efipart_strategy(void *, int, daddr_t, size_t, char *, size_t *);
 static int efipart_realstrategy(void *, int, daddr_t, size_t, char *, size_t *);
 
-static int efipart_open(struct open_file *, ...);
+static int efipart_open(struct open_file *);
 static int efipart_close(struct open_file *);
 static int efipart_ioctl(struct open_file *, u_long, void *);
 
@@ -881,21 +881,15 @@
 }
 
 static int
-efipart_open(struct open_file *f, ...)
+efipart_open(struct open_file *f)
 {
-	va_list args;
-	struct disk_devdesc *dev;
+	struct devdesc *dev;
 	pdinfo_t *pd;
 	EFI_BLOCK_IO *blkio;
 	EFI_STATUS status;
 
-	va_start(args, f);
-	dev = va_arg(args, struct disk_devdesc *);
-	va_end(args);
-	if (dev == NULL)
-		return (EINVAL);
-
-	pd = efiblk_get_pdinfo((struct devdesc *)dev);
+	dev = f->f_devdata;
+	pd = efiblk_get_pdinfo(dev);
 	if (pd == NULL)
 		return (EIO);
 
@@ -914,10 +908,10 @@
 	if (pd->pd_bcache == NULL)
 		pd->pd_bcache = bcache_allocate();
 
-	if (dev->dd.d_dev->dv_type == DEVT_DISK) {
+	if (dev->d_dev->dv_type == DEVT_DISK) {
 		int rc;
 
-		rc = disk_open(dev,
+		rc = disk_open((struct disk_devdesc *)dev,
 		    blkio->Media->BlockSize * (blkio->Media->LastBlock + 1),
 		    blkio->Media->BlockSize);
 		if (rc != 0) {
diff --git a/stand/i386/libfirewire/firewire.c b/stand/i386/libfirewire/firewire.c
--- a/stand/i386/libfirewire/firewire.c
+++ b/stand/i386/libfirewire/firewire.c
@@ -68,7 +68,7 @@
 static int	fw_init(void);
 static int	fw_strategy(void *devdata, int flag, daddr_t dblk,
 		    size_t size, char *buf, size_t *rsize);
-static int	fw_open(struct open_file *f, ...);
+static int	fw_open(struct open_file *f);
 static int	fw_close(struct open_file *f);
 static int	fw_print(int verbose);
 static void	fw_cleanup(void);
@@ -176,18 +176,8 @@
 }
 
 static int 
-fw_open(struct open_file *f, ...)
+fw_open(struct open_file *f __unused)
 {
-#if 0
-    va_list			ap;
-    struct i386_devdesc		*dev;
-    struct open_disk		*od;
-    int				error;
-
-    va_start(ap, f);
-    dev = va_arg(ap, struct i386_devdesc *);
-    va_end(ap);
-#endif
 
     return (ENXIO);
 }
diff --git a/stand/i386/libi386/biosdisk.c b/stand/i386/libi386/biosdisk.c
--- a/stand/i386/libi386/biosdisk.c
+++ b/stand/i386/libi386/biosdisk.c
@@ -147,7 +147,7 @@
     char *buf, size_t *rsize);
 static int bd_realstrategy(void *devdata, int flag, daddr_t dblk, size_t size,
     char *buf, size_t *rsize);
-static int bd_open(struct open_file *f, ...);
+static int bd_open(struct open_file *f);
 static int bd_close(struct open_file *f);
 static int bd_ioctl(struct open_file *f, u_long cmd, void *data);
 static int bd_print(int verbose);
@@ -837,20 +837,16 @@
  *  slice before it?)
  */
 static int
-bd_open(struct open_file *f, ...)
+bd_open(struct open_file *f)
 {
+	struct devdesc *dev;
 	bdinfo_t *bd;
-	struct disk_devdesc *dev;
-	va_list ap;
 	int rc;
 
 	TSENTER();
 
-	va_start(ap, f);
-	dev = va_arg(ap, struct disk_devdesc *);
-	va_end(ap);
-
-	bd = bd_get_bdinfo(&dev->dd);
+	dev = f->f_devdata;
+	bd = bd_get_bdinfo(dev);
 	if (bd == NULL)
 		return (EIO);
 
@@ -864,13 +860,13 @@
 	    bd->bd_bcache = bcache_allocate();
 
 	if (bd->bd_open == 0)
-		bd->bd_sectors = bd_disk_get_sectors(dev);
+		bd->bd_sectors = bd_disk_get_sectors((struct disk_devdesc *)dev);
 	bd->bd_open++;
 
 	rc = 0;
-	if (dev->dd.d_dev->dv_type == DEVT_DISK) {
-		rc = disk_open(dev, bd->bd_sectors * bd->bd_sectorsize,
-		    bd->bd_sectorsize);
+	if (dev->d_dev->dv_type == DEVT_DISK) {
+		rc = disk_open((struct disk_devdesc *)dev,
+		    bd->bd_sectors * bd->bd_sectorsize, bd->bd_sectorsize);
 		if (rc != 0) {
 			bd->bd_open--;
 			if (bd->bd_open == 0) {
diff --git a/stand/kboot/hostdisk.c b/stand/kboot/hostdisk.c
--- a/stand/kboot/hostdisk.c
+++ b/stand/kboot/hostdisk.c
@@ -34,7 +34,7 @@
 static int hostdisk_init(void);
 static int hostdisk_strategy(void *devdata, int flag, daddr_t dblk,
     size_t size, char *buf, size_t *rsize);
-static int hostdisk_open(struct open_file *f, ...);
+static int hostdisk_open(struct open_file *f);
 static int hostdisk_close(struct open_file *f);
 static int hostdisk_ioctl(struct open_file *f, u_long cmd, void *data);
 static int hostdisk_print(int verbose);
@@ -88,15 +88,11 @@
 }
 
 static int
-hostdisk_open(struct open_file *f, ...)
+hostdisk_open(struct open_file *f)
 {
 	struct devdesc *desc;
-	va_list vl;
-
-	va_start(vl, f);
-	desc = va_arg(vl, struct devdesc *);
-	va_end(vl);
 
+	desc = f->f_devdata;
 	desc->d_unit = host_open(desc->d_opendata, O_RDONLY, 0);
 
 	if (desc->d_unit <= 0) {
diff --git a/stand/kboot/hostfs.c b/stand/kboot/hostfs.c
--- a/stand/kboot/hostfs.c
+++ b/stand/kboot/hostfs.c
@@ -249,7 +249,7 @@
  * 'Open' the host device.
  */
 static int
-host_dev_open(struct open_file *f, ...)
+host_dev_open(struct open_file *f)
 {
 	return (0);
 }
diff --git a/stand/libofw/ofw_disk.c b/stand/libofw/ofw_disk.c
--- a/stand/libofw/ofw_disk.c
+++ b/stand/libofw/ofw_disk.c
@@ -45,7 +45,7 @@
 static int	ofwd_init(void);
 static int	ofwd_strategy(void *devdata, int flag, daddr_t dblk,
 		    size_t size, char *buf, size_t *rsize);
-static int	ofwd_open(struct open_file *f, ...);
+static int	ofwd_open(struct open_file *f);
 static int	ofwd_close(struct open_file *f);
 static int	ofwd_ioctl(struct open_file *f, u_long cmd, void *data);
 static int	ofwd_print(int verbose);
@@ -118,15 +118,11 @@
 }
 
 static int
-ofwd_open(struct open_file *f, ...)
+ofwd_open(struct open_file *f)
 {
 	struct ofw_devdesc *dp;
-	va_list vl;
-
-	va_start(vl, f);
-	dp = va_arg(vl, struct ofw_devdesc *);
-	va_end(vl);
 
+	dp = (struct ofw_devdesc *)f->f_devdata;
 	if (dp != kdp) {
 		if (kdp != NULL) {
 			OF_close(kdp->d_handle);
diff --git a/stand/libsa/geli/gelidev.c b/stand/libsa/geli/gelidev.c
--- a/stand/libsa/geli/gelidev.c
+++ b/stand/libsa/geli/gelidev.c
@@ -37,7 +37,7 @@
 
 static int  geli_dev_init(void);
 static int  geli_dev_strategy(void *, int, daddr_t, size_t, char *, size_t *);
-static int  geli_dev_open(struct open_file *f, ...);
+static int  geli_dev_open(struct open_file *f);
 static int  geli_dev_close(struct open_file *f);
 static int  geli_dev_ioctl(struct open_file *, u_long, void *);
 static int  geli_dev_print(int);
@@ -201,7 +201,7 @@
 }
 
 static int
-geli_dev_open(struct open_file *f, ...)
+geli_dev_open(struct open_file *f __unused)
 {
 
 	/*
diff --git a/stand/libsa/libsa.3 b/stand/libsa/libsa.3
--- a/stand/libsa/libsa.3
+++ b/stand/libsa/libsa.3
@@ -705,7 +705,7 @@
     int		(*dv_init)(void);
     int		(*dv_strategy)(void *devdata, int rw, daddr_t blk,
 			size_t size, char *buf, size_t *rsize);
-    int		(*dv_open)(struct open_file *f, ...);
+    int		(*dv_open)(struct open_file *f);
     int		(*dv_close)(struct open_file *f);
     int		(*dv_ioctl)(struct open_file *f, u_long cmd, void *data);
     int		(*dv_print)(int verbose);
diff --git a/stand/libsa/stand.h b/stand/libsa/stand.h
--- a/stand/libsa/stand.h
+++ b/stand/libsa/stand.h
@@ -154,7 +154,7 @@
     int		(*dv_init)(void);	/* early probe call */
     int		(*dv_strategy)(void *devdata, int rw, daddr_t blk,
 			size_t size, char *buf, size_t *rsize);
-    int		(*dv_open)(struct open_file *f, ...);
+    int		(*dv_open)(struct open_file *f);
     int		(*dv_close)(struct open_file *f);
     int		(*dv_ioctl)(struct open_file *f, u_long cmd, void *data);
     int		(*dv_print)(int verbose);	/* print device information */
@@ -174,8 +174,13 @@
  * versions may be larger, but should be allowed to
  * overlap.
  */
+/*
+ * XXX We do enough casts to disk_devdesc that a dev2disk would likely be a good
+ * idea.
+ */
 struct devdesc {
     struct devsw	*d_dev;
+    size_t		d_size;
     int			d_unit;
     void		*d_opendata;
 };
diff --git a/stand/libsa/zfs/zfs.c b/stand/libsa/zfs/zfs.c
--- a/stand/libsa/zfs/zfs.c
+++ b/stand/libsa/zfs/zfs.c
@@ -1564,18 +1564,14 @@
  * Attempt to open the pool described by (dev) for use by (f).
  */
 static int
-zfs_dev_open(struct open_file *f, ...)
+zfs_dev_open(struct open_file *f)
 {
-	va_list		args;
 	struct zfs_devdesc	*dev;
 	struct zfsmount	*mount;
 	spa_t		*spa;
 	int		rv;
 
-	va_start(args, f);
-	dev = va_arg(args, struct zfs_devdesc *);
-	va_end(args);
-
+	dev = (struct zfs_devdesc *)f->f_devdata;
 	if ((spa = spa_find_by_dev(dev)) == NULL)
 		return (ENXIO);
 
diff --git a/stand/uboot/main.c b/stand/uboot/main.c
--- a/stand/uboot/main.c
+++ b/stand/uboot/main.c
@@ -378,7 +378,7 @@
 		for (currdev.dd.d_unit = 0; currdev.dd.d_unit < UB_MAX_DEV;
 		     currdev.dd.d_unit++) {
 			print_disk_probe_info();
-			open_result = devsw[devidx]->dv_open(&f, &currdev);
+			open_result = devsw[devidx]->dv_open(&f);
 			if (open_result == 0) {
 				printf(" good.\n");
 				return (0);
@@ -396,7 +396,7 @@
 			if (currdev.dd.d_unit == -1)
 				break;
 			print_disk_probe_info();
-			open_result = devsw[devidx]->dv_open(&f, &currdev);
+			open_result = devsw[devidx]->dv_open(&f);
 			if (open_result == 0) {
 				printf(" good.\n");
 				return (0);
@@ -408,7 +408,7 @@
 
 	if ((currdev.dd.d_unit = uboot_diskgetunit(load_type, load_unit)) != -1) {
 		print_disk_probe_info();
-		open_result = devsw[devidx]->dv_open(&f,&currdev);
+		open_result = devsw[devidx]->dv_open(&f);
 		if (open_result == 0) {
 			printf(" good.\n");
 			return (0);
diff --git a/stand/uboot/uboot_disk.c b/stand/uboot/uboot_disk.c
--- a/stand/uboot/uboot_disk.c
+++ b/stand/uboot/uboot_disk.c
@@ -74,7 +74,7 @@
 /* devsw I/F */
 static int stor_init(void);
 static int stor_strategy(void *, int, daddr_t, size_t, char *, size_t *);
-static int stor_open(struct open_file *, ...);
+static int stor_open(struct open_file *);
 static int stor_close(struct open_file *);
 static int stor_ioctl(struct open_file *f, u_long cmd, void *data);
 static int stor_print(int);
@@ -174,16 +174,10 @@
 }
 
 static int
-stor_open(struct open_file *f, ...)
+stor_open(struct open_file *f)
 {
-	va_list ap;
-	struct disk_devdesc *dev;
-
-	va_start(ap, f);
-	dev = va_arg(ap, struct disk_devdesc *);
-	va_end(ap);
 
-	return (stor_opendev(dev));
+	return (stor_opendev((struct disk_devdesc *)f->f_devdata));
 }
 
 static int
diff --git a/stand/usb/storage/umass_loader.c b/stand/usb/storage/umass_loader.c
--- a/stand/usb/storage/umass_loader.c
+++ b/stand/usb/storage/umass_loader.c
@@ -44,7 +44,7 @@
 #include "umass_common.h"
 
 static int umass_disk_init(void);
-static int umass_disk_open(struct open_file *,...);
+static int umass_disk_open(struct open_file *);
 static int umass_disk_close(struct open_file *);
 static void umass_disk_cleanup(void);
 static int umass_disk_ioctl(struct open_file *, u_long, void *);
@@ -122,20 +122,16 @@
 }
 
 static int
-umass_disk_open(struct open_file *f,...)
+umass_disk_open(struct open_file *f)
 {
-	va_list ap;
-	struct disk_devdesc *dev;
-
-	va_start(ap, f);
-	dev = va_arg(ap, struct disk_devdesc *);
-	va_end(ap);
+	struct devdesc *dev;
 
+	dev = f->f_devdata;
 	if (umass_uaa.device == NULL)
 		return (ENXIO);
 	if (dev->d_unit != 0)
 		return (EIO);
-	return (umass_disk_open_sub(dev));
+	return (umass_disk_open_sub((struct disk_devdesc *)dev));
 }
 
 static int
diff --git a/stand/userboot/userboot/host.c b/stand/userboot/userboot/host.c
--- a/stand/userboot/userboot/host.c
+++ b/stand/userboot/userboot/host.c
@@ -133,7 +133,7 @@
  * 'Open' the host device.
  */
 static int
-host_dev_open(struct open_file *f, ...)
+host_dev_open(struct open_file *f __unused)
 {
 
 	return (0);
diff --git a/stand/userboot/userboot/main.c b/stand/userboot/userboot/main.c
--- a/stand/userboot/userboot/main.c
+++ b/stand/userboot/userboot/main.c
@@ -266,15 +266,19 @@
 #endif
 
 	if (userboot_disk_maxunit > 0) {
+		struct open_file f = { 0 };
+
 		dev.dd.d_dev = &userboot_disk;
 		dev.dd.d_unit = 0;
 		dev.d_slice = D_SLICEWILD;
 		dev.d_partition = D_PARTWILD;
+		f.f_devdata = &dev;
+
 		/*
 		 * If we cannot auto-detect the partition type then
 		 * access the disk as a raw device.
 		 */
-		if (dev.dd.d_dev->dv_open(NULL, &dev)) {
+		if (dev.dd.d_dev->dv_open(&f)) {
 			dev.d_slice = D_SLICENONE;
 			dev.d_partition = D_PARTNONE;
 		}
diff --git a/stand/userboot/userboot/userboot_disk.c b/stand/userboot/userboot/userboot_disk.c
--- a/stand/userboot/userboot/userboot_disk.c
+++ b/stand/userboot/userboot/userboot_disk.c
@@ -57,7 +57,7 @@
 		    size_t size, char *buf, size_t *rsize);
 static int	userdisk_realstrategy(void *devdata, int flag, daddr_t dblk,
 		    size_t size, char *buf, size_t *rsize);
-static int	userdisk_open(struct open_file *f, ...);
+static int	userdisk_open(struct open_file *f);
 static int	userdisk_close(struct open_file *f);
 static int	userdisk_ioctl(struct open_file *f, u_long cmd, void *data);
 static int	userdisk_print(int verbose);
@@ -156,22 +156,18 @@
  * Attempt to open the disk described by (dev) for use by (f).
  */
 static int
-userdisk_open(struct open_file *f, ...)
+userdisk_open(struct open_file *f)
 {
-	va_list			ap;
-	struct disk_devdesc	*dev;
+	struct devdesc *dev;
 
-	va_start(ap, f);
-	dev = va_arg(ap, struct disk_devdesc *);
-	va_end(ap);
-
-	if (dev->dd.d_unit < 0 || dev->dd.d_unit >= userdisk_maxunit)
+	dev = f->f_devdata;
+	if (dev->d_unit < 0 || dev->d_unit >= userdisk_maxunit)
 		return (EIO);
-	ud_info[dev->dd.d_unit].ud_open++;
-	if (ud_info[dev->dd.d_unit].ud_bcache == NULL)
-		ud_info[dev->dd.d_unit].ud_bcache = bcache_allocate();
-	return (disk_open(dev, ud_info[dev->dd.d_unit].mediasize,
-	    ud_info[dev->dd.d_unit].sectorsize));
+	ud_info[dev->d_unit].ud_open++;
+	if (ud_info[dev->d_unit].ud_bcache == NULL)
+		ud_info[dev->d_unit].ud_bcache = bcache_allocate();
+	return (disk_open((struct disk_devdesc *)dev,
+	    ud_info[dev->d_unit].mediasize, ud_info[dev->d_unit].sectorsize));
 }
 
 static int