From: Nick Piggin <nickpiggin@yahoo.com.au>

Move the invocation of ->writepage for to-be-reclaimed pages into
its own function "pageout".

From: Nikita Danilov <nikita@namesys.com>
with small changes from Nick Piggin
Signed-off-by: Nick Piggin <nickpiggin@cyberone.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>