1 files changed, 56 insertions, 0 deletions
diff --git a/src/basic/ioprio.h b/src/basic/ioprio.h
new file mode 100644
index 0000000..3fb168d
--- /dev/null
+++ b/src/basic/ioprio.h
@@ -0,0 +1,56 @@
+#ifndef IOPRIO_H
+#define IOPRIO_H
+
+/* This is minimal version of Linux' linux/ioprio.h header file, which
+ * is licensed GPL2 */
+
+#include <sys/syscall.h>
+#include <unistd.h>
+
+/*
+ * Gives us 8 prio classes with 13-bits of data for each class
+ */
+#define IOPRIO_BITS             16
+#define IOPRIO_N_CLASSES        8
+#define IOPRIO_CLASS_SHIFT      13
+#define IOPRIO_PRIO_MASK        ((1UL << IOPRIO_CLASS_SHIFT) - 1)
+
+#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
+#define IOPRIO_PRIO_DATA(mask)  ((mask) & IOPRIO_PRIO_MASK)
+#define IOPRIO_PRIO_VALUE(class, data)  (((class) << IOPRIO_CLASS_SHIFT) | data)
+
+#define ioprio_valid(mask)      (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
+
+/*
+ * These are the io priority groups as implemented by CFQ. RT is the realtime
+ * class, it always gets premium service. BE is the best-effort scheduling
+ * class, the default for any process. IDLE is the idle scheduling class, it
+ * is only served when no one else is using the disk.
+ */
+enum {
+        IOPRIO_CLASS_NONE,
+        IOPRIO_CLASS_RT,
+        IOPRIO_CLASS_BE,
+        IOPRIO_CLASS_IDLE,
+};
+
+/*
+ * 8 best effort priority levels are supported
+ */
+#define IOPRIO_BE_NR    (8)
+
+enum {
+        IOPRIO_WHO_PROCESS = 1,
+        IOPRIO_WHO_PGRP,
+        IOPRIO_WHO_USER,
+};
+
+static inline int ioprio_set(int which, int who, int ioprio) {
+        return syscall(__NR_ioprio_set, which, who, ioprio);
+}
+
+static inline int ioprio_get(int which, int who) {
+        return syscall(__NR_ioprio_get, which, who);
+}
+
+#endif