--- sys/fs/devfs/devfs.h	2008-06-22 14:09:46.000000000 +0200
+++ sys/fs/devfs/devfs.h	2008-06-22 15:27:46.000000000 +0200
@@ -111,10 +111,11 @@ 
 #define	DEVFSIO_RGETNEXT       	_IOWR('D', 4, struct devfs_rule)
 
 #define	DEVFSIO_SUSE		_IOW('D', 10, devfs_rsnum)
 #define	DEVFSIO_SAPPLY		_IOW('D', 11, devfs_rsnum)
 #define	DEVFSIO_SGETNEXT	_IOWR('D', 12, devfs_rsnum)
+#define	DEVFSIO_SGETCURRENT	_IOWR('D', 13, devfs_rsnum)
 
 /* XXX: DEVFSIO_RS_GET_INFO for refcount, active if any, etc. */
 
 #ifdef _KERNEL
 
--- sys/fs/devfs/devfs_rule.c	2008-03-20 17:08:42.000000000 +0100
+++ sys/fs/devfs/devfs_rule.c	2008-06-22 15:58:30.000000000 +0200
@@ -285,10 +285,13 @@ 
 			error = ESRCH;
 			break;
 		}
 		devfs_ruleset_applydm(ds, dm);
 		break;
+	case DEVFSIO_SGETCURRENT:
+		*(devfs_rsnum *)data = dm->dm_ruleset;
+		break;
 	case DEVFSIO_SGETNEXT:
 		rsnum = *(devfs_rsnum *)data;
 		TAILQ_FOREACH(ds, &devfs_rulesets, ds_list) {
 			if (ds->ds_number > rsnum)
 				break;
--- sbin/devfs/rule.c	2008-06-22 15:19:59.000000000 +0200
+++ sbin/devfs/rule.c	2008-06-22 15:20:03.000000000 +0200
@@ -53,19 +53,20 @@ 
 static void rulespec_intok(struct devfs_rule *dr, int ac, char **av,
     devfs_rsnum rsnum);
 static void rulespec_outfp(FILE *fp, struct devfs_rule *dr);
 
 static command_t rule_add, rule_apply, rule_applyset;
-static command_t rule_del, rule_delset, rule_show, rule_showsets;
+static command_t rule_del, rule_delset, rule_show, rule_showset, rule_showsets;
 
 static ctbl_t ctbl_rule = {
 	{ "add",		rule_add },
 	{ "apply",		rule_apply },
 	{ "applyset",		rule_applyset },
 	{ "del",		rule_del },
 	{ "delset",		rule_delset },
 	{ "show",		rule_show },
+	{ "showset",		rule_showset },
 	{ "showsets",		rule_showsets },
 	{ NULL,			NULL }
 };
 
 static struct intstr ist_type[] = {
@@ -227,10 +228,26 @@ 
 	}
 	return (0);
 }
 
 static int
+rule_showset(int ac, char **av __unused)
+{
+	devfs_rsnum rsnum;
+
+	if (ac != 1)
+		usage();
+
+	if (ioctl(mpfd, DEVFSIO_SGETCURRENT, &rsnum) != -1)
+		printf("%d\n", rsnum);
+
+	if (errno != 0)
+		err(1, "ioctl DEVFSIO_SGETCURRENT");
+	return (0);
+}
+
+static int
 rule_showsets(int ac, char **av __unused)
 {
 	devfs_rsnum rsnum;
 
 	if (ac != 1)
--- sbin/devfs/devfs.8	2006-12-29 23:45:12.000000000 +0100
+++ sbin/devfs/devfs.8	2008-06-22 15:40:06.000000000 +0200
@@ -132,10 +132,12 @@ 
 Display the rule number
 .Ar rulenum ,
 or all the rules in the ruleset.
 The output lines (one line per rule) are expected to be valid
 .Ar rulespec Ns s .
+.It Cm rule showset
+Display the number of the ruleset associated with the mount-point.
 .It Cm rule showsets
 Report the numbers of existing rulesets.
 .It Cm ruleset Ar ruleset
 Set ruleset number
 .Ar ruleset