1 files changed, 69 insertions, 0 deletions

diff --git a/lib/lockref.c b/lib/lockref.c
new file mode 100644
index 000000000000..a9a4f4e1eff5
--- /dev/null
+++ b/lib/lockref.c
@@ -0,0 +1,69 @@
+#include <linux/export.h>
+#include <linux/lockref.h>
+
+/**
+ * lockref_get - Increments reference count unconditionally
+ * @lockcnt: pointer to lockref structure
+ *
+ * This operation is only valid if you already hold a reference
+ * to the object, so you know the count cannot be zero.
+ */
+void lockref_get(struct lockref *lockref)
+{
+        spin_lock(&lockref->lock);
+        lockref->count++;
+        spin_unlock(&lockref->lock);
+}
+EXPORT_SYMBOL(lockref_get);
+
+/**
+ * lockref_get_not_zero - Increments count unless the count is 0
+ * @lockcnt: pointer to lockref structure
+ * Return: 1 if count updated successfully or 0 if count was zero
+ */
+int lockref_get_not_zero(struct lockref *lockref)
+{
+        int retval = 0;
+
+        spin_lock(&lockref->lock);
+        if (lockref->count) {
+                lockref->count++;
+                retval = 1;
+        }
+        spin_unlock(&lockref->lock);
+        return retval;
+}
+EXPORT_SYMBOL(lockref_get_not_zero);
+
+/**
+ * lockref_get_or_lock - Increments count unless the count is 0
+ * @lockcnt: pointer to lockref structure
+ * Return: 1 if count updated successfully or 0 if count was zero
+ * and we got the lock instead.
+ */
+int lockref_get_or_lock(struct lockref *lockref)
+{
+        spin_lock(&lockref->lock);
+        if (!lockref->count)
+                return 0;
+        lockref->count++;
+        spin_unlock(&lockref->lock);
+        return 1;
+}
+EXPORT_SYMBOL(lockref_get_or_lock);
+
+/**
+ * lockref_put_or_lock - decrements count unless count <= 1 before decrement
+ * @lockcnt: pointer to lockref structure
+ * Return: 1 if count updated successfully or 0 if count <= 1 and lock taken
+ */
+int lockref_put_or_lock(struct lockref *lockref)
+{
+        spin_lock(&lockref->lock);
+        if (lockref->count <= 1)
+                return 0;
+        lockref->count--;
+        spin_unlock(&lockref->lock);
+        return 1;
+}
+EXPORT_SYMBOL(lockref_put_or_lock);