- Add the library function read_cache_pages(), which is used in a
    similar fashion to the single page 'read_cache_page()'. It hides
    the details of the LRU cache etc. from a filesystem that wants to
    to populate an address space with a list of pages.

  - Fix NFS so that readahead uses the ->readpages() interface. Means
    that we can immediately schedule an RPC call in order to complete
    the I/O, rather than relying on somebody later triggering it by
    calling lock_page() (and hence sync_page()). The sync_page()
    method is race-prone, since the waiting page may try to call it
    before we've finished initializing the 'struct nfs_page'.

  - Clear out nfs_sync_page(), the nfs_inode->read list, and
    friends. When the I/O completion gets scheduled in ->readpage(),
    ->readpages(), they have no reason to exist.