Fix a wrong comment over page_cache_async_readahead().
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Acked-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>