writeback: update wb_over_bg_thresh() to use wb_domain aware operations (947e9762) · Commits · 戴 / test

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:

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>

mm/page-writeback.c

+12 −5

Original line number	Original line	Diff line number	Diff line
	@@ -1749,15 +1749,22 @@ EXPORT_SYMBOL(balance_dirty_pages_ratelimited);
	*/		*/
	bool wb_over_bg_thresh(struct bdi_writeback *wb)		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) +		if (gdtc->dirty > gdtc->bg_thresh)
	global_page_state(NR_UNSTABLE_NFS) > background_thresh)
	return true;		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 true;

	return false;		return false;

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