Add more functions for handling mount arguments in VFS_MOUNT():

vfs_flagopt() for binary/boolean options.
vfs_getopts() for string options
vfs_filteropt() to check for unknown options.
vfs_scanopt() for scanf() like processing of options.

Also add function for setting the stat.f_mntfromname field.

sys/kern/vfs_mount.c

@@ -121,6 +121,18 @@ struct vnode	*rootvnode;
  *              to locate its physical store
  */
 
+/*
+ * Global opts, taken by all filesystems
+ */
+static const char *global_opts[] = {
+	"fstype",
+	"fspath",
+	"ro",
+	"suid",
+	"exec",
+	NULL
+};
+
 /*
  * The root specifiers we will try if RB_CDROM is specified.
  */
@@ -1381,6 +1393,41 @@ DB_SHOW_COMMAND(disk, db_getdiskbyname)
 }
 #endif
 
+/*
+ * ---------------------------------------------------------------------
+ * Functions for querying mount options/arguments from filesystems.
+ */
+
+/*
+ * Check that no unknown options are given
+ */
+int
+vfs_filteropt(struct vfsoptlist *opts, const char **legal)
+{
+	struct vfsopt *opt;
+	const char **t, *p;
+	
+
+	TAILQ_FOREACH(opt, opts, link) {
+		p = opt->name;
+		if (p[0] == 'n' && p[1] == 'o')
+			p += 2;
+		for(t = global_opts; *t != NULL; t++)
+			if (!strcmp(*t, p))
+				break;
+		if (*t != NULL)
+			continue;
+		for(t = legal; *t != NULL; t++)
+			if (!strcmp(*t, p))
+				break;
+		if (*t != NULL)
+			continue;
+		printf("mount option <%s> is unknown\n", p);
+		return (EINVAL);
+	}
+	return (0);
+}
+
 /*
  * Get a mount option by its name.
  *
@@ -1412,6 +1459,62 @@ vfs_getopt(opts, name, buf, len)
 	return (ENOENT);
 }
 
+char *
+vfs_getopts(struct vfsoptlist *opts, const char *name, int *error)
+{
+	struct vfsopt *opt;
+
+	*error = 0;
+	TAILQ_FOREACH(opt, opts, link) {
+		if (strcmp(name, opt->name) != 0)
+			continue;
+		if (((char *)opt->value)[opt->len - 1] != '\0') {
+			*error = EINVAL;
+			return (NULL);
+		}
+		return (opt->value);
+	}
+	return (NULL);
+}
+
+int
+vfs_flagopt(struct vfsoptlist *opts, const char *name, u_int *w, u_int val)
+{
+	struct vfsopt *opt;
+
+	TAILQ_FOREACH(opt, opts, link) {
+		if (strcmp(name, opt->name) == 0) {
+			if (w != NULL)
+				*w |= val;
+			return (1);
+		}
+	}
+	if (w != NULL)
+		*w &= ~val;
+	return (0);
+}
+
+int
+vfs_scanopt(struct vfsoptlist *opts, const char *name, const char *fmt, ...)
+{
+	va_list ap;
+	struct vfsopt *opt;
+	int ret;
+
+	KASSERT(opts != NULL, ("vfs_getopt: caller passed 'opts' as NULL"));
+
+	TAILQ_FOREACH(opt, opts, link) {
+		if (strcmp(name, opt->name) != 0)
+			continue;
+		if (((char *)opt->value)[opt->len - 1] != '\0')
+			return (0);
+		va_start(ap, fmt);
+		ret = vsscanf(opt->value, fmt, ap);
+		va_end(ap);
+		return (ret);
+	}
+	return (0);
+}
 /*
  * Find and copy a mount option.
  *
@@ -1481,6 +1584,15 @@ __vfs_statfs(struct mount *mp, struct statfs *sbp, struct thread *td)
 	return (error);
 }
 
+void
+vfs_mountedfrom(struct mount *mp, const char *from)
+{
+
+	bzero(mp->mnt_stat.f_mntfromname, sizeof mp->mnt_stat.f_mntfromname);
+	strlcpy(mp->mnt_stat.f_mntfromname, from,
+	    sizeof mp->mnt_stat.f_mntfromname);
+}
+
 /*
  * ---------------------------------------------------------------------
  * This is the api for building mount args and mounting filesystems from

sys/sys/mount.h

@@ -571,8 +571,12 @@ struct mntarg *mount_argsu(struct mntarg *ma, const char *name, const void *val,
 struct vfsconf *vfs_byname(const char *);
 struct vfsconf *vfs_byname_kld(const char *, struct thread *td, int *);
 void	vfs_event_signal(fsid_t *, u_int32_t, intptr_t);
+int	vfs_flagopt(struct vfsoptlist *opts, const char *name, u_int *w, u_int val);
 int	vfs_getopt(struct vfsoptlist *, const char *, void **, int *);
+char	*vfs_getopts(struct vfsoptlist *, const char *, int *error);
 int	vfs_copyopt(struct vfsoptlist *, const char *, void *, int);
+int	vfs_filteropt(struct vfsoptlist *, const char **legal);
+int	vfs_scanopt(struct vfsoptlist *opts, const char *name, const char *fmt, ...);
 int	vfs_setpublicfs			    /* set publicly exported fs */
 	    (struct mount *, struct netexport *, struct export_args *);
 int	vfs_lock(struct mount *);         /* lock a vfs */
@@ -589,6 +593,7 @@ struct cdev *vfs_getrootfsid(struct mount *);
 struct	mount *vfs_getvfs(fsid_t *);      /* return vfs given fsid */
 int	vfs_modevent(module_t, int, void *);
 void	vfs_mountroot(void);			/* mount our root filesystem */
+void	vfs_mountedfrom(struct mount *, const char *from);
 void	vfs_mount_destroy(struct mount *, struct thread *);
 int	vfs_suser(struct mount *, struct thread *);
 void	vfs_unbusy(struct mount *, struct thread *);