1 files changed, 177 insertions, 0 deletions
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
new file mode 100644
index 00000000..5edc9014
--- /dev/null
+++ b/include/linux/percpu_counter.h
@@ -0,0 +1,177 @@
+#ifndef _LINUX_PERCPU_COUNTER_H
+#define _LINUX_PERCPU_COUNTER_H
+/*
+ * A simple "approximate counter" for use in ext2 and ext3 superblocks.
+ *
+ * WARNING: these things are HUGE.  4 kbytes per counter on 32-way P4.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/list.h>
+#include <linux/threads.h>
+#include <linux/percpu.h>
+#include <linux/types.h>
+
+#ifdef CONFIG_SMP
+
+struct percpu_counter {
+	spinlock_t lock;
+	s64 count;
+#ifdef CONFIG_HOTPLUG_CPU
+	struct list_head list;	/* All percpu_counters are on a list */
+#endif
+	s32 __percpu *counters;
+};
+
+extern int percpu_counter_batch;
+
+int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,
+			  struct lock_class_key *key);
+
+#define percpu_counter_init(fbc, value)					\
+	({								\
+		static struct lock_class_key __key;			\
+									\
+		__percpu_counter_init(fbc, value, &__key);		\
+	})
+
+void percpu_counter_destroy(struct percpu_counter *fbc);
+void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
+void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
+s64 __percpu_counter_sum(struct percpu_counter *fbc);
+int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs);
+
+static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
+{
+	__percpu_counter_add(fbc, amount, percpu_counter_batch);
+}
+
+static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
+{
+	s64 ret = __percpu_counter_sum(fbc);
+	return ret < 0 ? 0 : ret;
+}
+
+static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
+{
+	return __percpu_counter_sum(fbc);
+}
+
+static inline s64 percpu_counter_read(struct percpu_counter *fbc)
+{
+	return fbc->count;
+}
+
+/*
+ * It is possible for the percpu_counter_read() to return a small negative
+ * number for some counter which should never be negative.
+ *
+ */
+static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
+{
+	s64 ret = fbc->count;
+
+	barrier();		/* Prevent reloads of fbc->count */
+	if (ret >= 0)
+		return ret;
+	return 0;
+}
+
+static inline int percpu_counter_initialized(struct percpu_counter *fbc)
+{
+	return (fbc->counters != NULL);
+}
+
+#else
+
+struct percpu_counter {
+	s64 count;
+};
+
+static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
+{
+	fbc->count = amount;
+	return 0;
+}
+
+static inline void percpu_counter_destroy(struct percpu_counter *fbc)
+{
+}
+
+static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
+{
+	fbc->count = amount;
+}
+
+static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
+{
+	if (fbc->count > rhs)
+		return 1;
+	else if (fbc->count < rhs)
+		return -1;
+	else
+		return 0;
+}
+
+static inline void
+percpu_counter_add(struct percpu_counter *fbc, s64 amount)
+{
+	preempt_disable();
+	fbc->count += amount;
+	preempt_enable();
+}
+
+static inline void
+__percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
+{
+	percpu_counter_add(fbc, amount);
+}
+
+static inline s64 percpu_counter_read(struct percpu_counter *fbc)
+{
+	return fbc->count;
+}
+
+/*
+ * percpu_counter is intended to track positive numbers. In the UP case the
+ * number should never be negative.
+ */
+static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
+{
+	return fbc->count;
+}
+
+static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
+{
+	return percpu_counter_read_positive(fbc);
+}
+
+static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
+{
+	return percpu_counter_read(fbc);
+}
+
+static inline int percpu_counter_initialized(struct percpu_counter *fbc)
+{
+	return 1;
+}
+
+#endif	/* CONFIG_SMP */
+
+static inline void percpu_counter_inc(struct percpu_counter *fbc)
+{
+	percpu_counter_add(fbc, 1);
+}
+
+static inline void percpu_counter_dec(struct percpu_counter *fbc)
+{
+	percpu_counter_add(fbc, -1);
+}
+
+static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
+{
+	percpu_counter_add(fbc, -amount);
+}
+
+#endif /* _LINUX_PERCPU_COUNTER_H */