Since now bdi->max_ratio is part per million, fix the wrong arithmetic
for max_prop_frac when setting max_ratio. Otherwise the miscalculated
max_prop_frac will affect the incrementing of writeout completion count
when max_ratio is not 100%.
Fixes: efc3e6ad53ea ("mm: split off __bdi_set_max_ratio() function")
Signed-off-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx>
---
mm/page-writeback.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 2140382dd768..dda59b368c01 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -728,7 +728,8 @@ static int __bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ra
ret = -EINVAL;
} else {
bdi->max_ratio = max_ratio;
- bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100;
+ bdi->max_prop_frac = div64_u64(FPROP_FRAC_BASE * max_ratio,
+ 100 * BDI_RATIO_SCALE);
}
spin_unlock_bh(&bdi_lock);
--
2.19.1.6.gb485710b
