writeback: fix ppc compile warnings on do_div(long long, unsigned long)

Fix powerpc compile warnings

mm/page-writeback.c: In function 'bdi_position_ratio':
mm/page-writeback.c:622:3: warning: comparison of distinct pointer types lacks a cast [enabled by default]
page-writeback.c:635:4: warning: comparison of distinct pointer types lacks a cast [enabled by default]

Also fix gcc "uninitialized var" warnings.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 325f753c80ed7ac098baec9e2f85c26026a28993..0802d5177997a0a8ae29833cf79372a431865acc 100644 (file)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -618,8 +618,8 @@ static unsigned long bdi_position_ratio(struct backing_dev_info *bdi,
        x_intercept = bdi_setpoint + span;
 
        if (bdi_dirty < x_intercept - span / 4) {
-               pos_ratio *= x_intercept - bdi_dirty;
-               do_div(pos_ratio, x_intercept - bdi_setpoint + 1);
+               pos_ratio = div_u64(pos_ratio * (x_intercept - bdi_dirty),
+                                   x_intercept - bdi_setpoint + 1);
        } else
                pos_ratio /= 4;
 
@@ -630,10 +630,9 @@ static unsigned long bdi_position_ratio(struct backing_dev_info *bdi,
         */
        x_intercept = bdi_thresh / 2;
        if (bdi_dirty < x_intercept) {
-               if (bdi_dirty > x_intercept / 8) {
-                       pos_ratio *= x_intercept;
-                       do_div(pos_ratio, bdi_dirty);
-               } else
+               if (bdi_dirty > x_intercept / 8)
+                       pos_ratio = div_u64(pos_ratio * x_intercept, bdi_dirty);
+               else
                        pos_ratio *= 8;
        }
 
@@ -1010,10 +1009,10 @@ static void balance_dirty_pages(struct address_space *mapping,
        unsigned long dirty_thresh;
        unsigned long bdi_thresh;
        long pause = 0;
-       long max_pause;
+       long uninitialized_var(max_pause);
        bool dirty_exceeded = false;
        unsigned long task_ratelimit;
-       unsigned long dirty_ratelimit;
+       unsigned long uninitialized_var(dirty_ratelimit);
        unsigned long pos_ratio;
        struct backing_dev_info *bdi = mapping->backing_dev_info;
        unsigned long start_time = jiffies;