Merge tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux

Pull writeback fixes from Wu Fengguang:
 "Two writeback fixes

   - fix negative (setpoint - dirty) in 32bit archs

   - use down_read_trylock() in writeback_inodes_sb(_nr)_if_idle()"

* tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  Negative (setpoint-dirty) in bdi_position_ratio()
  vfs: re-implement writeback_inodes_sb(_nr)_if_idle() and rename them

1 files changed, 1 insertions, 1 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 742c40583159..efe68148f621 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -696,7 +696,7 @@ static unsigned long bdi_position_ratio(struct backing_dev_info *bdi,
          *     => fast response on large errors; small oscillation near setpoint
          */
         setpoint = (freerun + limit) / 2;
-        x = div_s64((setpoint - dirty) << RATELIMIT_CALC_SHIFT,
+        x = div_s64(((s64)setpoint - (s64)dirty) << RATELIMIT_CALC_SHIFT,
                     limit - setpoint + 1);
         pos_ratio = x;
         pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT;