[PATCH 10/19] writeback: add dirty_throttle_control->wb_completions

Tejun Heo
2015-04-06T20:05:13Z

wb->completions measures the wb's proportional write bandwidth in
global_wb_domain and thus naturally tied to the wb_domain. This patch
adds dirty_throttle_control->wb_completions which is initialized to
wb->completions by GDTC_INIT() and updates __wb_dirty_limits() to use
it instead of dereferencing wb->completions directly.

This will allow dirty_throttle_control to represent different
wb_domains and the matching wb completions.

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>
---
mm/page-writeback.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 3450520..15771a6 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -127,6 +127,7 @@ struct wb_domain global_wb_domain;
/* consolidated parameters for balance_dirty_pages() and its subroutines */
struct dirty_throttle_control {
struct bdi_writeback *wb;
+ struct fprop_local_percpu *wb_completions;

unsigned long dirty; /* file_dirty + write + nfs */
unsigned long thresh; /* dirty threshold */
@@ -139,7 +140,8 @@ struct dirty_throttle_control {
unsigned long pos_ratio;
};

-#define GDTC_INIT(__wb) .wb = (__wb)
+#define GDTC_INIT(__wb) .wb = (__wb), \
+ .wb_completions = &(__wb)->completions

/*
* Length of period for aging writeout fractions of bdis. This is an
@@ -590,7 +592,7 @@ static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc)
/*
* Calculate this BDI's share of the thresh ratio.
*/
- fprop_fraction_percpu(&dom->completions, &dtc->wb->completions,
+ fprop_fraction_percpu(&dom->completions, dtc->wb_completions,
&numerator, &denominator);

wb_thresh = (thresh * (100 - bdi_min_ratio)) / 100;
--
2.1.0