[PATCH] count ghost references to vfsmounts

make propagate_mount_busy() exclude references from the vfsmounts
that had been isolated by umount_tree() and are just waiting for
release_mounts() to dispose of their ->mnt_parent/->mnt_mountpoint.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/pnode.c b/fs/pnode.c
index 05ba692..1d8f544 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -225,7 +225,7 @@
  */
 static inline int do_refcount_check(struct vfsmount *mnt, int count)
 {
-	int mycount = atomic_read(&mnt->mnt_count);
+	int mycount = atomic_read(&mnt->mnt_count) - mnt->mnt_ghosts;
 	return (mycount > count);
 }