NFS takes some thought to switch to the new symlink scheme, because we
can't rely on the pagecache lookup to find the symlink page when freeing
it - the cache might have been invalidated in the meantime. 

So we hide the page information in the symlink data area itself,
by stealing the last pointer in the page used for the cache. That
way nfs_put_link() can just look up the page directly.
Signed-off-by: Al Viro <viro@parcelfarce.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>