mm/page-writeback.c: dirty limit type should be unsigned long

get_dirty_limits() calls clip_bdi_dirty_limit() and task_dirty_limit()
with variable pbdi_dirty as one of the arguments.  This variable is an
unsigned long * but both functions expect it to be a long *.  This causes
the following sparse warnings:

  warning: incorrect type in argument 3 (different signedness)
     expected long *pbdi_dirty
     got unsigned long *pbdi_dirty
  warning: incorrect type in argument 2 (different signedness)
     expected long *pdirty
     got unsigned long *pbdi_dirty

Fix the warnings by changing the long * to unsigned long * in both
functions.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index bb553c3..7b0dcea 100644 (file)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -265,18 +265,19 @@ static void bdi_writeout_fraction(struct backing_dev_info *bdi,
  * This avoids exceeding the total dirty_limit when the floating averages
  * fluctuate too quickly.
  */
-static void
-clip_bdi_dirty_limit(struct backing_dev_info *bdi, long dirty, long *pbdi_dirty)
+static void clip_bdi_dirty_limit(struct backing_dev_info *bdi,
+               unsigned long dirty, unsigned long *pbdi_dirty)
 {
-       long avail_dirty;
+       unsigned long avail_dirty;
 
-       avail_dirty = dirty -
-               (global_page_state(NR_FILE_DIRTY) +
+       avail_dirty = global_page_state(NR_FILE_DIRTY) +
                 global_page_state(NR_WRITEBACK) +
                 global_page_state(NR_UNSTABLE_NFS) +
-                global_page_state(NR_WRITEBACK_TEMP));
+                global_page_state(NR_WRITEBACK_TEMP);
 
-       if (avail_dirty < 0)
+       if (avail_dirty < dirty)
+               avail_dirty = dirty - avail_dirty;
+       else
                avail_dirty = 0;
 
        avail_dirty += bdi_stat(bdi, BDI_RECLAIMABLE) +
@@ -299,10 +300,10 @@ static inline void task_dirties_fraction(struct task_struct *tsk,
  *
  *   dirty -= (dirty/8) * p_{t}
  */
-static void task_dirty_limit(struct task_struct *tsk, long *pdirty)
+static void task_dirty_limit(struct task_struct *tsk, unsigned long *pdirty)
 {
        long numerator, denominator;
-       long dirty = *pdirty;
+       unsigned long dirty = *pdirty;
        u64 inv = dirty >> 3;
 
        task_dirties_fraction(tsk, &numerator, &denominator);