writeback: add dirty_throttle_control->dom

Currently all dirty throttle operations use global_wb_domain; however,
cgroup writeback support requires considering per-memcg wb_domain too.
This patch adds dirty_throttle_control->dom and updates functions
which are directly using globabl_wb_domain to use it instead.

As this makes global_update_bandwidth() a misnomer, the function is
renamed to domain_update_bandwidth().

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>

1 files changed, 24 insertions, 6 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 5b439fc1e95e..38d45d8c71f5 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -126,6 +126,9 @@ struct wb_domain global_wb_domain;
 
 /* consolidated parameters for balance_dirty_pages() and its subroutines */
 struct dirty_throttle_control {
+#ifdef CONFIG_CGROUP_WRITEBACK
+        struct wb_domain        *dom;
+#endif
         struct bdi_writeback    *wb;
         struct fprop_local_percpu *wb_completions;
 
@@ -140,7 +143,7 @@ struct dirty_throttle_control {
         unsigned long           pos_ratio;
 };
 
-#define GDTC_INIT(__wb)         .wb = (__wb),                           \
+#define DTC_INIT_COMMON(__wb)   .wb = (__wb),                           \
                                 .wb_completions = &(__wb)->completions
 
 /*
@@ -152,6 +155,14 @@ struct dirty_throttle_control {
 
 #ifdef CONFIG_CGROUP_WRITEBACK
 
+#define GDTC_INIT(__wb)         .dom = &global_wb_domain,               \
+                                DTC_INIT_COMMON(__wb)
+
+static struct wb_domain *dtc_dom(struct dirty_throttle_control *dtc)
+{
+        return dtc->dom;
+}
+
 static void wb_min_max_ratio(struct bdi_writeback *wb,
                              unsigned long *minp, unsigned long *maxp)
 {
@@ -181,6 +192,13 @@ static void wb_min_max_ratio(struct bdi_writeback *wb,
 
 #else   /* CONFIG_CGROUP_WRITEBACK */
 
+#define GDTC_INIT(__wb)         DTC_INIT_COMMON(__wb)
+
+static struct wb_domain *dtc_dom(struct dirty_throttle_control *dtc)
+{
+        return &global_wb_domain;
+}
+
 static void wb_min_max_ratio(struct bdi_writeback *wb,
                              unsigned long *minp, unsigned long *maxp)
 {
@@ -583,7 +601,7 @@ static unsigned long hard_dirty_limit(unsigned long thresh)
  */
 static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc)
 {
-        struct wb_domain *dom = &global_wb_domain;
+        struct wb_domain *dom = dtc_dom(dtc);
         unsigned long thresh = dtc->thresh;
         u64 wb_thresh;
         long numerator, denominator;
@@ -952,7 +970,7 @@ out:
 
 static void update_dirty_limit(struct dirty_throttle_control *dtc)
 {
-        struct wb_domain *dom = &global_wb_domain;
+        struct wb_domain *dom = dtc_dom(dtc);
         unsigned long thresh = dtc->thresh;
         unsigned long limit = dom->dirty_limit;
 
@@ -979,10 +997,10 @@ update:
         dom->dirty_limit = limit;
 }
 
-static void global_update_bandwidth(struct dirty_throttle_control *dtc,
+static void domain_update_bandwidth(struct dirty_throttle_control *dtc,
                                     unsigned long now)
 {
-        struct wb_domain *dom = &global_wb_domain;
+        struct wb_domain *dom = dtc_dom(dtc);
 
         /*
          * check locklessly first to optimize away locking for the most time
@@ -1190,7 +1208,7 @@ static void __wb_update_bandwidth(struct dirty_throttle_control *dtc,
                 goto snapshot;
 
         if (update_ratelimit) {
-                global_update_bandwidth(dtc, now);
+                domain_update_bandwidth(dtc, now);
                 wb_update_dirty_ratelimit(dtc, dirtied, elapsed);
         }
         wb_update_write_bandwidth(wb, elapsed, written);