writeback: move over_bground_thresh() to mm/page-writeback.c

and rename it to wb_over_bg_thresh().  The function is closely tied to
the dirty throttling mechanism implemented in page-writeback.c.  This
relocation will allow future updates necessary for cgroup writeback
support.

While at it, add function comment.

This is pure reorganization and doesn't introduce any behavioral
changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 2 insertions, 18 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 51c8a5b..da35587 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1071,22 +1071,6 @@ static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
 	return nr_pages - work.nr_pages;
 }
 
-static bool over_bground_thresh(struct bdi_writeback *wb)
-{
-	unsigned long background_thresh, dirty_thresh;
-
-	global_dirty_limits(&background_thresh, &dirty_thresh);
-
-	if (global_page_state(NR_FILE_DIRTY) +
-	    global_page_state(NR_UNSTABLE_NFS) > background_thresh)
-		return true;
-
-	if (wb_stat(wb, WB_RECLAIMABLE) > wb_calc_thresh(wb, background_thresh))
-		return true;
-
-	return false;
-}
-
 /*
  * Explicit flushing or periodic writeback of "old" data.
  *
@@ -1136,7 +1120,7 @@ static long wb_writeback(struct bdi_writeback *wb,
 		 * For background writeout, stop when we are below the
 		 * background dirty threshold
 		 */
-		if (work->for_background && !over_bground_thresh(wb))
+		if (work->for_background && !wb_over_bg_thresh(wb))
 			break;
 
 		/*
@@ -1227,7 +1211,7 @@ static unsigned long get_nr_dirty_pages(void)
 
 static long wb_check_background_flush(struct bdi_writeback *wb)
 {
-	if (over_bground_thresh(wb)) {
+	if (wb_over_bg_thresh(wb)) {
 
 		struct wb_writeback_work work = {
 			.nr_pages	= LONG_MAX,