Function vfs_mountroot_devfs

freebsd/kern/vfs_mountroot.c:249–305

}

static int
vfs_mountroot_devfs(struct thread *td, struct mount **mpp)
{
	struct vfsoptlist *opts;
	struct vfsconf *vfsp;
	struct mount *mp;
	int error;

	*mpp = NULL;

	if (rootdevmp != NULL) {
		/*
		 * Already have /dev; this happens during rerooting.
		 */
		error = vfs_busy(rootdevmp, 0);
		if (error != 0)
			return (error);
		*mpp = rootdevmp;
	} else {
		vfsp = vfs_byname("devfs");
		KASSERT(vfsp != NULL, ("Could not find devfs by name"));
		if (vfsp == NULL)
			return (ENOENT);

		mp = vfs_mount_alloc(NULLVP, vfsp, "/dev", td->td_ucred);

		error = VFS_MOUNT(mp);
		KASSERT(error == 0, ("VFS_MOUNT(devfs) failed %d", error));
		if (error)
			return (error);

		error = VFS_STATFS(mp, &mp->mnt_stat);
		KASSERT(error == 0, ("VFS_STATFS(devfs) failed %d", error));
		if (error)
			return (error);

		opts = malloc(sizeof(struct vfsoptlist), M_MOUNT, M_WAITOK);
		TAILQ_INIT(opts);
		mp->mnt_opt = opts;

		mtx_lock(&mountlist_mtx);
		TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
		mtx_unlock(&mountlist_mtx);

		*mpp = mp;
		rootdevmp = mp;
		vfs_op_exit(mp);
	}

	set_rootvnode();

	error = kern_symlinkat(td, "/", AT_FDCWD, "dev", UIO_SYSSPACE);
	if (error)
		printf("kern_symlink /dev -> / returns %d\n", error);

	return (error);
}