mm: vmscan: remove dead code related to lumpy reclaim waiting on pages under writeback

mm: vmscan: remove dead code related to lumpy reclaim waiting on pages under writeback

Lumpy reclaim worked with two passes - the first which queued pages for IO
and the second which waited on writeback.  As direct reclaim can no longer
write pages there is some dead code.  This patch removes it but direct
reclaim will continue to wait on pages under writeback while in
synchronous reclaim mode.

Signed-off-by: Mel Gorman <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Wu Fengguang <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Alex Elder <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Dave Hansen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>