[RFC][-mm] [4/7] handle limit change

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Add an interface to set limit. This is necessary to memory resource controller
because it shrinks usage at set limit.

(*) Other controller may not need this interface to shrink usage because
    shrinking is not necessary or impossible under it.

Changelog:
  - fixed white space bug.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>


 include/linux/res_counter.h |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

Index: test-2.6.26-rc5-mm3++/include/linux/res_counter.h
===================================================================
--- test-2.6.26-rc5-mm3++.orig/include/linux/res_counter.h
+++ test-2.6.26-rc5-mm3++/include/linux/res_counter.h
@@ -158,4 +158,19 @@ static inline void res_counter_reset_fai
 	cnt->failcnt = 0;
 	spin_unlock_irqrestore(&cnt->lock, flags);
 }
+
+static inline int res_counter_set_limit(struct res_counter *cnt,
+	unsigned long long limit)
+{
+	unsigned long flags;
+	int ret = -EBUSY;
+
+	spin_lock_irqsave(&cnt->lock, flags);
+	if (cnt->usage < limit) {
+		cnt->limit = limit;
+		ret = 0;
+	}
+	spin_unlock_irqrestore(&cnt->lock, flags);
+	return ret;
+}
 #endif

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