stand: Change disk_fmtdev to take a struct devdesc *

We do a number of games with ploymorphism for different types struct
*devdesc. Adjust one place that this affects to take the address of the
base class (most others have void * at the moment). This is more type
safe than a bare void *.

Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D35914

stand/common/disk.c

@@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
 #include <stdarg.h>
 #include <bootstrap.h>
 #include <part.h>
+#include <assert.h>
 
 #include "disk.h"
 
@@ -386,11 +387,13 @@ disk_close(struct disk_devdesc *dev)
 }
 
 char *
-disk_fmtdev(struct disk_devdesc *dev)
+disk_fmtdev(struct devdesc *vdev)
 {
+	struct disk_devdesc *dev = (struct disk_devdesc *)vdev;
 	static char buf[128];
 	char *cp;
 
+	assert(vdev->d_dev->dv_type == DEVT_DISK);
 	cp = buf + sprintf(buf, "%s%d", dev->dd.d_dev->dv_name, dev->dd.d_unit);
 	if (dev->d_slice > D_SLICENONE) {
 #ifdef LOADER_GPT_SUPPORT

stand/common/disk.h

@@ -116,7 +116,8 @@ extern int ptblread(void *, void *, size_t, uint64_t);
  * Print information about slices on a disk.
  */
 extern int disk_print(struct disk_devdesc *, char *, int);
-extern char* disk_fmtdev(struct disk_devdesc *);
 extern int disk_parsedev(struct disk_devdesc *, const char *, const char **);
 
+char *disk_fmtdev(struct devdesc *vdev);
+
 #endif	/* _DISK_H */

stand/libsa/geli/gelidev.c

@@ -305,7 +305,7 @@ geli_probe_and_attach(struct open_file *f)
 	hlastblk = (hmediasize / DEV_BSIZE) - 1;
 
 	/* Taste the host provider.  If it's not geli-encrypted just return. */
-	gdev = geli_taste(diskdev_read, hdesc, hlastblk, disk_fmtdev(hdesc));
+	gdev = geli_taste(diskdev_read, hdesc, hlastblk, disk_fmtdev(&hdesc->dd));
 	if (gdev == NULL)
 		return;