It fixes a crash in NTFS on architectures where flush_dcache_page()
is a real function.  I never noticed this as all my testing is done on
i386 where flush_dcache_page() is NULL.

http://bugzilla.kernel.org/show_bug.cgi?id=6700

Many thanks to Pauline Ng for the detailed bug report and analysis!
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>