+EXPORT_SYMBOL_GPL(do_add_mount);
+
+static void expire_mount(struct vfsmount *mnt, struct list_head *mounts,
+ struct list_head *umounts)
+{
+ spin_lock(&vfsmount_lock);
+
+ /*
+ * Check if mount is still attached, if not, let whoever holds it deal
+ * with the sucker
+ */
+ if (mnt->mnt_parent == mnt) {
+ spin_unlock(&vfsmount_lock);
+ return;
+ }
+
+ /*
+ * Check that it is still dead: the count should now be 2 - as
+ * contributed by the vfsmount parent and the mntget above
+ */
+ if (!propagate_mount_busy(mnt, 2)) {
+ /* delete from the namespace */
+ touch_namespace(mnt->mnt_namespace);
+ list_del_init(&mnt->mnt_list);
+ mnt->mnt_namespace = NULL;
+ umount_tree(mnt, 1, umounts);
+ spin_unlock(&vfsmount_lock);
+ } else {
+ /*
+ * Someone brought it back to life whilst we didn't have any
+ * locks held so return it to the expiration list
+ */
+ list_add_tail(&mnt->mnt_expire, mounts);
+ spin_unlock(&vfsmount_lock);
+ }
+}
+
+/*
+ * process a list of expirable mountpoints with the intent of discarding any
+ * mountpoints that aren't in use and haven't been touched since last we came
+ * here
+ */
+void mark_mounts_for_expiry(struct list_head *mounts)
+{
+ struct namespace *namespace;
+ struct vfsmount *mnt, *next;
+ LIST_HEAD(graveyard);
+
+ if (list_empty(mounts))
+ return;
+
+ spin_lock(&vfsmount_lock);
+
+ /* extract from the expiration list every vfsmount that matches the
+ * following criteria:
+ * - only referenced by its parent vfsmount
+ * - still marked for expiry (marked on the last call here; marks are
+ * cleared by mntput())
+ */
+ list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
+ if (!xchg(&mnt->mnt_expiry_mark, 1) ||
+ atomic_read(&mnt->mnt_count) != 1)
+ continue;
+
+ mntget(mnt);
+ list_move(&mnt->mnt_expire, &graveyard);
+ }
+
+ /*
+ * go through the vfsmounts we've just consigned to the graveyard to
+ * - check that they're still dead
+ * - delete the vfsmount from the appropriate namespace under lock
+ * - dispose of the corpse
+ */
+ while (!list_empty(&graveyard)) {
+ LIST_HEAD(umounts);
+ mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire);
+ list_del_init(&mnt->mnt_expire);
+
+ /* don't do anything if the namespace is dead - all the
+ * vfsmounts from it are going away anyway */
+ namespace = mnt->mnt_namespace;
+ if (!namespace || !namespace->root)
+ continue;
+ get_namespace(namespace);
+
+ spin_unlock(&vfsmount_lock);
+ down_write(&namespace_sem);
+ expire_mount(mnt, mounts, &umounts);
+ up_write(&namespace_sem);
+ release_mounts(&umounts);
+ mntput(mnt);
+ put_namespace(namespace);
+ spin_lock(&vfsmount_lock);
+ }
+
+ spin_unlock(&vfsmount_lock);
+}
+
+EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
+
+/*
+ * Some copy_from_user() implementations do not return the exact number of
+ * bytes remaining to copy on a fault. But copy_mount_options() requires that.
+ * Note that this function differs from copy_from_user() in that it will oops
+ * on bad values of `to', rather than returning a short copy.
+ */
+static long exact_copy_from_user(void *to, const void __user * from,
+ unsigned long n)
+{
+ char *t = to;
+ const char __user *f = from;
+ char c;
+
+ if (!access_ok(VERIFY_READ, from, n))
+ return n;
+
+ while (n) {
+ if (__get_user(c, f)) {
+ memset(t, 0, n);
+ break;
+ }
+ *t++ = c;
+ f++;
+ n--;
+ }
+ return n;
+}
+
+int copy_mount_options(const void __user * data, unsigned long *where)