1 files changed, 10 insertions, 1 deletions

diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index c9d625ca659e..da81af086eaf 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -109,12 +109,18 @@ void res_counter_init(struct res_counter *counter, struct res_counter *parent);
  *
  * returns 0 on success and <0 if the counter->usage will exceed the
  * counter->limit _locked call expects the counter->lock to be taken
+ *
+ * charge_nofail works the same, except that it charges the resource
+ * counter unconditionally, and returns < 0 if the after the current
+ * charge we are over limit.
  */
 
 int __must_check res_counter_charge_locked(struct res_counter *counter,
                 unsigned long val);
 int __must_check res_counter_charge(struct res_counter *counter,
                 unsigned long val, struct res_counter **limit_fail_at);
+int __must_check res_counter_charge_nofail(struct res_counter *counter,
+                unsigned long val, struct res_counter **limit_fail_at);
 
 /*
  * uncharge - tell that some portion of the resource is released
@@ -142,7 +148,10 @@ static inline unsigned long long res_counter_margin(struct res_counter *cnt)
         unsigned long flags;
 
         spin_lock_irqsave(&cnt->lock, flags);
-        margin = cnt->limit - cnt->usage;
+        if (cnt->limit > cnt->usage)
+                margin = cnt->limit - cnt->usage;
+        else
+                margin = 0;
         spin_unlock_irqrestore(&cnt->lock, flags);
         return margin;
 }