347  * domain_dirty_limits - calculate thresh and bg_thresh for a wb_domain
350  * Calculate @dtc->thresh and ->bg_thresh considering
364 	unsigned long thresh;  in domain_dirty_limits()  local
389 		thresh = DIV_ROUND_UP(bytes, PAGE_SIZE);  in domain_dirty_limits()
391 		thresh = (ratio * available_memory) / PAGE_SIZE;  in domain_dirty_limits()
401 		thresh += thresh / 4 + global_wb_domain.dirty_limit / 32;  in domain_dirty_limits()
407 	if (thresh > UINT_MAX)  in domain_dirty_limits()
408 		thresh = UINT_MAX;  in domain_dirty_limits()
410 	if (bg_thresh >= thresh)  in domain_dirty_limits()
411 		bg_thresh = thresh / 2;  in domain_dirty_limits()
412 	dtc->thresh = thresh;  in domain_dirty_limits()
417 		trace_global_dirty_state(bg_thresh, thresh);  in domain_dirty_limits()
423  * @pdirty: out parameter for thresh
425  * Calculate bg_thresh and thresh for global_wb_domain.  See
436 	*pdirty = gdtc.thresh;  in global_dirty_limits()
821 static unsigned long dirty_freerun_ceiling(unsigned long thresh,  in dirty_freerun_ceiling()  argument
824 	return (thresh + bg_thresh) / 2;  in dirty_freerun_ceiling()
828 				      unsigned long thresh)  in hard_dirty_limit()  argument
830 	return max(thresh, dom->dirty_limit);  in hard_dirty_limit()
879  * @thresh: dirty throttling or dirty background threshold of wb_domain in @dtc
901 				      unsigned long thresh)  in __wb_calc_thresh()  argument
911 	 * Calculate this wb's share of the thresh ratio.  in __wb_calc_thresh()
916 	wb_thresh = (thresh * (100 * BDI_RATIO_SCALE - bdi_min_ratio)) / (100 * BDI_RATIO_SCALE);  in __wb_calc_thresh()
922 	wb_thresh += (thresh * wb_min_ratio) / (100 * BDI_RATIO_SCALE);  in __wb_calc_thresh()
931 	if (thresh > dtc->dirty) {  in __wb_calc_thresh()
933 			wb_thresh = max(wb_thresh, (thresh - dtc->dirty) / 100);  in __wb_calc_thresh()
935 			wb_thresh = max(wb_thresh, (thresh - dtc->dirty) / 8);  in __wb_calc_thresh()
938 	wb_max_thresh = thresh * wb_max_ratio / (100 * BDI_RATIO_SCALE);  in __wb_calc_thresh()
945 unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh)  in wb_calc_thresh()  argument
950 	return __wb_calc_thresh(&gdtc, thresh);  in wb_calc_thresh()
962 	return __wb_calc_thresh(&mdtc, mdtc.thresh);  in cgwb_calc_thresh()
1069  * - the wb dirty thresh drops quickly due to change of JBOD workload
1075 	unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh);  in wb_position_ratio()
1076 	unsigned long limit = dtc->limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh);  in wb_position_ratio()
1192 	if (unlikely(wb_thresh > dtc->thresh))  in wb_position_ratio()
1193 		wb_thresh = dtc->thresh;  in wb_position_ratio()
1196 	 *	wb_setpoint = setpoint * wb_thresh / thresh  in wb_position_ratio()
1198 	x = div_u64((u64)wb_thresh << 16, dtc->thresh | 1);  in wb_position_ratio()
1202 	 * (thresh - wb_thresh ~= 0) and transit to wb_thresh in JBOD case.  in wb_position_ratio()
1204 	 *        wb_thresh                    thresh - wb_thresh  in wb_position_ratio()
1206 	 *         thresh                           thresh  in wb_position_ratio()
1208 	span = (dtc->thresh - wb_thresh + 8 * write_bw) * (u64)x >> 16;  in wb_position_ratio()
1287 	unsigned long thresh = dtc->thresh;  in update_dirty_limit()  local
1293 	if (limit < thresh) {  in update_dirty_limit()
1294 		limit = thresh;  in update_dirty_limit()
1299 	 * Follow down slowly. Use the higher one as the target, because thresh  in update_dirty_limit()
1303 	thresh = max(thresh, dtc->dirty);  in update_dirty_limit()
1304 	if (limit > thresh) {  in update_dirty_limit()
1305 		limit -= (limit - thresh) >> 5;  in update_dirty_limit()
1344 	unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh);  in wb_update_dirty_ratelimit()
1345 	unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh);  in wb_update_dirty_ratelimit()
1566 					 unsigned long thresh)  in dirty_poll_interval()  argument
1568 	if (thresh > dirty)  in dirty_poll_interval()
1569 		return 1UL << (ilog2(thresh - dirty) >> 1);  in dirty_poll_interval()
1686 	dtc->wb_thresh = __wb_calc_thresh(dtc, dtc->thresh);  in wb_dirty_limits()
1687 	dtc->wb_bg_thresh = dtc->thresh ?  in wb_dirty_limits()
1688 		div_u64((u64)dtc->wb_thresh * dtc->bg_thresh, dtc->thresh) : 0;  in wb_dirty_limits()
1695 	 * Otherwise it would be possible to get thresh+n pages  in wb_dirty_limits()
1696 	 * reported dirty, even though there are thresh-m pages  in wb_dirty_limits()
1712 	unsigned long dirty, thresh;  in domain_poll_intv()  local
1716 		thresh = dtc->wb_thresh;  in domain_poll_intv()
1719 		thresh = dtc->thresh;  in domain_poll_intv()
1722 	return dirty_poll_interval(dirty, thresh);  in domain_poll_intv()
1737 	unsigned long dirty, thresh, bg_thresh;  in domain_dirty_freerun()  local
1742 		thresh = dtc->wb_thresh;  in domain_dirty_freerun()
1746 		thresh = dtc->thresh;  in domain_dirty_freerun()
1749 	dtc->freerun = dirty <= dirty_freerun_ceiling(thresh, bg_thresh);  in domain_dirty_freerun()
1785 		((dtc->dirty > dtc->thresh) || strictlimit);  in wb_dirty_exceeded()
1986 		 * This is typically equal to (dirty < thresh) and can also  in balance_dirty_pages()
2124  * and thresh, but it's for background writeback.