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Commit 947e9762 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

writeback: update wb_over_bg_thresh() to use wb_domain aware operations 



wb_over_bg_thresh() currently uses global_dirty_limits() and
wb_dirty_limit() both of which are wrappers around operations which
take dirty_throttle_control.  For cgroup writeback support, the
function will be updated to also consider memcg wb_domains which
requires the context information carried in dirty_throttle_control.

This patch updates wb_over_bg_thresh() so that it uses the underlying
wb_domain aware operations directly and builds the global
dirty_throttle_control in the process.

This patch 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 aa661bbe

mm/page-writeback.c

+12 −5
Original line number Diff line number Diff line
@@ -1749,15 +1749,22 @@ EXPORT_SYMBOL(balance_dirty_pages_ratelimited); 
 */

bool wb_over_bg_thresh(struct bdi_writeback *wb)

{

	unsigned long background_thresh, dirty_thresh;

	struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) };

	struct dirty_throttle_control * const gdtc = &gdtc_stor;



	global_dirty_limits(&background_thresh, &dirty_thresh);

	/*

	 * Similar to balance_dirty_pages() but ignores pages being written

	 * as we're trying to decide whether to put more under writeback.

	 */

	gdtc->avail = global_dirtyable_memory();

	gdtc->dirty = global_page_state(NR_FILE_DIRTY) +

		      global_page_state(NR_UNSTABLE_NFS);

	domain_dirty_limits(gdtc);



	if (global_page_state(NR_FILE_DIRTY) +

	    global_page_state(NR_UNSTABLE_NFS) > background_thresh)

	if (gdtc->dirty > gdtc->bg_thresh)

		return true;



	if (wb_stat(wb, WB_RECLAIMABLE) > wb_calc_thresh(wb, background_thresh))

	if (wb_stat(wb, WB_RECLAIMABLE) > __wb_calc_thresh(gdtc))

		return true;



	return false;