Commit aa661bbe authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

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: default avatarTejun 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: default avatarJens Axboe <axboe@fb.com>
parent 9fc3a43e

fs/fs-writeback.c

+2 −18
Original line number Diff line number Diff line
@@ -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,

include/linux/writeback.h

+1 −0
Original line number Diff line number Diff line
@@ -207,6 +207,7 @@ unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh); 
void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time);

void page_writeback_init(void);

void balance_dirty_pages_ratelimited(struct address_space *mapping);

bool wb_over_bg_thresh(struct bdi_writeback *wb);



typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,

				void *data);

mm/page-writeback.c

+23 −0
Original line number Diff line number Diff line
@@ -1740,6 +1740,29 @@ void balance_dirty_pages_ratelimited(struct address_space *mapping) 
}

EXPORT_SYMBOL(balance_dirty_pages_ratelimited);



/**

 * wb_over_bg_thresh - does @wb need to be written back?

 * @wb: bdi_writeback of interest

 *

 * Determines whether background writeback should keep writing @wb or it's

 * clean enough.  Returns %true if writeback should continue.

 */

bool wb_over_bg_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;

}



void throttle_vm_writeout(gfp_t gfp_mask)

{

	unsigned long background_thresh;

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