mm: change dirty limit type specifiers to unsigned long

The background dirty and dirty limits are better defined with type
specifiers of unsigned long since negative writeback thresholds are not
possible.

These values, as returned by get_dirty_limits(), are normally compared
with ZVC values to determine whether writeback shall commence or be
throttled.  Such page counts cannot be negative, so declaring the page
limits as signed is unnecessary.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index e585657e9831..259e9ea58cab 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -125,8 +125,8 @@ struct file;
 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
                                       void __user *, size_t *, loff_t *);
 
-void get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
-                 struct backing_dev_info *bdi);
+void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
+                      unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 
 void page_writeback_init(void);
 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,