writeback: clean up wb_dirty_limit()
The function name wb_dirty_limit(), its argument @dirty and the local
variable @wb_dirty are mortally confusing given that the function
calculates per-wb threshold value not dirty pages, especially given
that @dirty and @wb_dirty are used elsewhere for dirty pages.
Let's rename the function to wb_calc_thresh() and wb_dirty to
wb_thresh.
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>
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 70cf98d..c7745a7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -556,7 +556,7 @@
}
/**
- * wb_dirty_limit - @wb's share of dirty throttling threshold
+ * wb_calc_thresh - @wb's share of dirty throttling threshold
* @wb: bdi_writeback to query
* @dirty: global dirty limit in pages
*
@@ -577,28 +577,28 @@
* The wb's share of dirty limit will be adapting to its throughput and
* bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set.
*/
-unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty)
+unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh)
{
- u64 wb_dirty;
+ u64 wb_thresh;
long numerator, denominator;
unsigned long wb_min_ratio, wb_max_ratio;
/*
- * Calculate this BDI's share of the dirty ratio.
+ * Calculate this BDI's share of the thresh ratio.
*/
wb_writeout_fraction(wb, &numerator, &denominator);
- wb_dirty = (dirty * (100 - bdi_min_ratio)) / 100;
- wb_dirty *= numerator;
- do_div(wb_dirty, denominator);
+ wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100;
+ wb_thresh *= numerator;
+ do_div(wb_thresh, denominator);
wb_min_max_ratio(wb, &wb_min_ratio, &wb_max_ratio);
- wb_dirty += (dirty * wb_min_ratio) / 100;
- if (wb_dirty > (dirty * wb_max_ratio) / 100)
- wb_dirty = dirty * wb_max_ratio / 100;
+ wb_thresh += (thresh * wb_min_ratio) / 100;
+ if (wb_thresh > (thresh * wb_max_ratio) / 100)
+ wb_thresh = thresh * wb_max_ratio / 100;
- return wb_dirty;
+ return wb_thresh;
}
/*
@@ -750,7 +750,7 @@
* total amount of RAM is 16GB, bdi->max_ratio is equal to 1%, global
* limits are set by default to 10% and 20% (background and throttle).
* Then wb_thresh is 1% of 20% of 16GB. This amounts to ~8K pages.
- * wb_dirty_limit(wb, bg_thresh) is about ~4K pages. wb_setpoint is
+ * wb_calc_thresh(wb, bg_thresh) is about ~4K pages. wb_setpoint is
* about ~6K pages (as the average of background and throttle wb
* limits). The 3rd order polynomial will provide positive feedback if
* wb_dirty is under wb_setpoint and vice versa.
@@ -1115,7 +1115,7 @@
*
* We rampup dirty_ratelimit forcibly if wb_dirty is low because
* it's possible that wb_thresh is close to zero due to inactivity
- * of backing device (see the implementation of wb_dirty_limit()).
+ * of backing device (see the implementation of wb_calc_thresh()).
*/
if (unlikely(wb->bdi->capabilities & BDI_CAP_STRICTLIMIT)) {
dirty = wb_dirty;
@@ -1123,7 +1123,7 @@
setpoint = wb_dirty + 1;
else
setpoint = (wb_thresh +
- wb_dirty_limit(wb, bg_thresh)) / 2;
+ wb_calc_thresh(wb, bg_thresh)) / 2;
}
if (dirty < setpoint) {
@@ -1352,7 +1352,7 @@
* wb_position_ratio() will let the dirtier task progress
* at some rate <= (write_bw / 2) for bringing down wb_dirty.
*/
- *wb_thresh = wb_dirty_limit(wb, dirty_thresh);
+ *wb_thresh = wb_calc_thresh(wb, dirty_thresh);
if (wb_bg_thresh)
*wb_bg_thresh = dirty_thresh ? div_u64((u64)*wb_thresh *