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/fs/fs-writeback.c b/fs/fs-writeback.c
index 881ea5d97c00105b5621e7746ffd2400dd3ac64f..b1b3b8184500484e2a4bfc8678b76a6e85a7ff0b 100644 (file)
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1081,7 +1081,7 @@ static bool over_bground_thresh(struct bdi_writeback *wb)
            global_page_state(NR_UNSTABLE_NFS) > background_thresh)
                return true;
 
-       if (wb_stat(wb, WB_RECLAIMABLE) > wb_dirty_limit(wb, background_thresh))
+       if (wb_stat(wb, WB_RECLAIMABLE) > wb_calc_thresh(wb, background_thresh))
                return true;
 
        return false;

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 23af355d547154072d52e56c70aebe2836ea9598..0435c85d4cfa03dcc3c12ebc5bdbc1905c50608a 100644 (file)
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -155,7 +155,7 @@ int dirty_writeback_centisecs_handler(struct ctl_table *, int,
                                      void __user *, size_t *, loff_t *);
 
 void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
-unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty);
+unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);
 
 void __wb_update_bandwidth(struct bdi_writeback *wb,
                           unsigned long thresh,

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index ad5608d01e8c02d49708e4c33ce859aaeaae88d9..9c8b7b5a0eeed02d21865c846300cb051a24fbcc 100644 (file)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -49,7 +49,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
        struct bdi_writeback *wb = &bdi->wb;
        unsigned long background_thresh;
        unsigned long dirty_thresh;
-       unsigned long bdi_thresh;
+       unsigned long wb_thresh;
        unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
        struct inode *inode;
 
@@ -67,7 +67,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
        spin_unlock(&wb->list_lock);
 
        global_dirty_limits(&background_thresh, &dirty_thresh);
-       bdi_thresh = wb_dirty_limit(wb, dirty_thresh);
+       wb_thresh = wb_calc_thresh(wb, dirty_thresh);
 
 #define K(x) ((x) << (PAGE_SHIFT - 10))
        seq_printf(m,
@@ -87,7 +87,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
                   "state:              %10lx\n",
                   (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
                   (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
-                  K(bdi_thresh),
+                  K(wb_thresh),
                   K(dirty_thresh),
                   K(background_thresh),
                   (unsigned long) K(wb_stat(wb, WB_DIRTIED)),

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 70cf98dc342309313cd816b9a8b9a1777e6282bb..c7745a7fe11e303f9a02948aa3c608fe87907187 100644 (file)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -556,7 +556,7 @@ static unsigned long hard_dirty_limit(unsigned long thresh)
 }
 
 /**
- * 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 @@ static unsigned long hard_dirty_limit(unsigned long thresh)
  * 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 @@ static unsigned long wb_position_ratio(struct bdi_writeback *wb,
         * 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 @@ static void wb_update_dirty_ratelimit(struct bdi_writeback *wb,
         *
         * 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 @@ static void wb_update_dirty_ratelimit(struct bdi_writeback *wb,
                        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 @@ static inline void wb_dirty_limits(struct bdi_writeback *wb,
         *   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 *