Function vfs_mountroot_shuffle

freebsd/kern/vfs_mountroot.c:307–426

}

static void
vfs_mountroot_shuffle(struct thread *td, struct mount *mpdevfs)
{
	struct nameidata nd;
	struct mount *mporoot, *mpnroot;
	struct vnode *vp, *vporoot, *vpdevfs;
	char *fspath;
	int error;

	mpnroot = TAILQ_NEXT(mpdevfs, mnt_list);

	/* Shuffle the mountlist. */
	mtx_lock(&mountlist_mtx);
	mporoot = TAILQ_FIRST(&mountlist);
	TAILQ_REMOVE(&mountlist, mpdevfs, mnt_list);
	if (mporoot != mpdevfs) {
		TAILQ_REMOVE(&mountlist, mpnroot, mnt_list);
		TAILQ_INSERT_HEAD(&mountlist, mpnroot, mnt_list);
	}
	TAILQ_INSERT_TAIL(&mountlist, mpdevfs, mnt_list);
	mtx_unlock(&mountlist_mtx);

	cache_purgevfs(mporoot);
	if (mporoot != mpdevfs)
		cache_purgevfs(mpdevfs);

	if (VFS_ROOT(mporoot, LK_EXCLUSIVE, &vporoot))
		panic("vfs_mountroot_shuffle: Cannot find root vnode");

	VI_LOCK(vporoot);
	vporoot->v_iflag &= ~VI_MOUNT;
	vn_irflag_unset_locked(vporoot, VIRF_MOUNTPOINT);
	vporoot->v_mountedhere = NULL;
	VI_UNLOCK(vporoot);
	mporoot->mnt_flag &= ~MNT_ROOTFS;
	mporoot->mnt_vnodecovered = NULL;
	vput(vporoot);

	/* Set up the new rootvnode, and purge the cache */
	mpnroot->mnt_vnodecovered = NULL;
	set_rootvnode();
	cache_purgevfs(rootvnode->v_mount);

	if (mporoot != mpdevfs) {
		/* Remount old root under /.mount or /mnt */
		fspath = "/.mount";
		NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
		    fspath, td);
		error = namei(&nd);
		if (error) {
			NDFREE(&nd, NDF_ONLY_PNBUF);
			fspath = "/mnt";
			NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
			    fspath, td);
			error = namei(&nd);
		}
		if (!error) {
			vp = nd.ni_vp;