mm: writeback: cleanups in preparation for per-zone dirty limits

The next patch will introduce per-zone dirty limiting functions in
addition to the traditional global dirty limiting.

Rename determine_dirtyable_memory() to global_dirtyable_memory() before
adding the zone-specific version, and fix up its documentation.

Also, move the functions to determine the dirtyable memory and the
function to calculate the dirty limit based on that together so that their
relationship is more apparent and that they can be commented on as a
group.

Signed-off-by: Johannes Weiner <[email protected]>
Reviewed-by: Minchan Kim <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Reviewed-by: Michal Hocko <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Wu Fengguang <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Chris Mason <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
1 file changed