Add io_wait_event_killable(), a variant of wait_event_killable() that
uses io_schedule() instead of schedule(). This is to be used in
situation where waiting time is to be accounted as IO wait time.

Signed-off-by: Remi Pommarel <repk@triplefau.lt>
---
 include/linux/wait.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 09855d819418..cfeb1adee973 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -937,6 +937,21 @@ extern int do_wait_intr_irq(wait_queue_head_t *, wait_queue_entry_t *);
 	__ret;									\
 })
 
+#define __io_wait_event_killable(wq, condition)					\
+	___wait_event(wq, condition, TASK_KILLABLE, 0, 0, io_schedule())
+
+/*
+ * wait_event_killable() - link wait_event_killable but with io_schedule()
+ */
+#define io_wait_event_killable(wq_head, condition)				\
+({										\
+	int __ret = 0;								\
+	might_sleep();								\
+	if (!(condition))							\
+		__ret = __io_wait_event_killable(wq_head, condition);		\
+	__ret;									\
+})
+
 #define __wait_event_state(wq, condition, state)				\
 	___wait_event(wq, condition, state, 0, 0, schedule())
 
-- 
2.50.1