Introduce the "ruleset=number" option for devfs(5) mounts.

Add support for updating the devfs mount (currently only changing the
ruleset number is supported).
Check mnt_optnew with vfs_filteropt(9).

This new option sets the specified ruleset number as the active ruleset
of the new devfs mount and applies all its rules at mount time. If the
specified ruleset doesn't exist, a new empty ruleset is created.

MFC after:	1 month

share/man/man5/devfs.5

@@ -38,7 +38,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 18, 2010
+.Dd February 9, 2012
 .Dt DEVFS 5
 .Os
 .Sh NAME
@@ -90,6 +90,29 @@ and
 .Pa 2 .
 .Xr fdescfs 5
 creates files for all open descriptors.
+.Pp
+The options are as follows:
+.Bl -tag -width indent
+.It Fl o Ar options
+Use the specified mount
+.Ar options ,
+as described in
+.Xr mount 8 .
+The following devfs file system-specific options are available:
+.Bl -tag -width indent
+.It Cm ruleset Ns No = Ns Ar ruleset
+Set ruleset number
+.Ar ruleset
+as the current ruleset for the mount-point and apply all its rules. If the
+ruleset number
+.Ar ruleset
+does not exist, an empty ruleset with the number
+.Ar ruleset
+is created. See
+.Xr devfs 8
+for more information on working with devfs rulesets.
+.El
+.El
 .Sh FILES
 .Bl -tag -width /dev/XXXX -compact
 .It Pa /dev

sys/fs/devfs/devfs.h

@@ -182,6 +182,8 @@ void	devfs_rules_apply(struct devfs_mount *, struct devfs_dirent *);
 void	devfs_rules_cleanup(struct devfs_mount *);
 int	devfs_rules_ioctl(struct devfs_mount *, u_long, caddr_t,
 	    struct thread *);
+void	devfs_ruleset_set(devfs_rsnum rsnum, struct devfs_mount *dm);
+void	devfs_ruleset_apply(struct devfs_mount *dm);
 int	devfs_allocv(struct devfs_dirent *, struct mount *, int,
 	    struct vnode **);
 char	*devfs_fqpn(char *, struct devfs_mount *, struct devfs_dirent *,

sys/fs/devfs/devfs_rule.c

@@ -771,3 +771,38 @@ devfs_rules_cleanup(struct devfs_mount *dm)
 		devfs_ruleset_reap(ds);
 	}
 }
+
+/*
+ * Make rsnum the active ruleset for dm (locked)
+ */
+void
+devfs_ruleset_set(devfs_rsnum rsnum, struct devfs_mount *dm)
+{
+
+	sx_assert(&dm->dm_lock, SX_XLOCKED);
+
+	sx_xlock(&sx_rules);
+	devfs_ruleset_use(rsnum, dm);
+	sx_xunlock(&sx_rules);
+}
+
+/*
+ * Apply the current active ruleset on a mount
+ */
+void
+devfs_ruleset_apply(struct devfs_mount *dm)
+{
+	struct devfs_ruleset *ds;
+
+	sx_assert(&dm->dm_lock, SX_XLOCKED);
+
+	sx_xlock(&sx_rules);
+	if (dm->dm_ruleset == 0) {
+		sx_xunlock(&sx_rules);
+		return;
+	}
+	ds = devfs_ruleset_bynum(dm->dm_ruleset);
+	if (ds != NULL)
+		devfs_ruleset_applydm(ds, dm);
+	sx_xunlock(&sx_rules);
+}

sys/fs/devfs/devfs_vfsops.c

@@ -56,6 +56,10 @@ static vfs_unmount_t	devfs_unmount;
 static vfs_root_t	devfs_root;
 static vfs_statfs_t	devfs_statfs;
 
+static const char *devfs_opts[] = {
+	"from", "ruleset", NULL
+};
+
 /*
  * Mount the filesystem
  */
@@ -65,15 +69,46 @@ devfs_mount(struct mount *mp)
 	int error;
 	struct devfs_mount *fmp;
 	struct vnode *rvp;
+	int rsnum;
 
 	if (devfs_unr == NULL)
 		devfs_unr = new_unrhdr(0, INT_MAX, NULL);
 
 	error = 0;
 
-	if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
+	if (mp->mnt_flag & MNT_ROOTFS)
 		return (EOPNOTSUPP);
 
+	rsnum = 0;
+
+	if (mp->mnt_optnew != NULL) {
+		if (vfs_filteropt(mp->mnt_optnew, devfs_opts))
+			return (EINVAL);
+
+		if (vfs_getopt(mp->mnt_optnew, "ruleset", NULL, NULL) == 0 &&
+		    (vfs_scanopt(mp->mnt_optnew, "ruleset", "%d",
+		    &rsnum) != 1 || rsnum < 0 || rsnum > 65535))
+			error = EINVAL;
+	}
+
+	if (error) {
+		vfs_mount_error(mp, "%s", "invalid ruleset specification");
+		return (error);
+	}
+
+	if (mp->mnt_flag & MNT_UPDATE) {
+		if (rsnum != 0) {
+			fmp = mp->mnt_data;
+			if (fmp != NULL) {
+				sx_xlock(&fmp->dm_lock);
+				devfs_ruleset_set((devfs_rsnum)rsnum, fmp);
+				devfs_ruleset_apply(fmp);
+				sx_xunlock(&fmp->dm_lock);
+			}
+		}
+		return (0);
+	}
+
 	fmp = malloc(sizeof *fmp, M_DEVFS, M_WAITOK | M_ZERO);
 	fmp->dm_idx = alloc_unr(devfs_unr);
 	sx_init(&fmp->dm_lock, "devfsmount");
@@ -101,6 +136,12 @@ devfs_mount(struct mount *mp)
 		return (error);
 	}
 
+	if (rsnum != 0) {
+		sx_xlock(&fmp->dm_lock);
+		devfs_ruleset_set((devfs_rsnum)rsnum, fmp);
+		sx_xunlock(&fmp->dm_lock);
+	}
+
 	VOP_UNLOCK(rvp, 0);
 
 	vfs_mountedfrom(mp, "devfs");