wait: Add wait_io_event_interruptible and friends

These these macros are the same as their "non-io" counterparts
but call io_schedule() instead of schedule(). This is useful for
indicating the time we are waiting should be considere as time
waiting on IO.

Change-Id: If7644d55052bfde559496a1c5b1567c8605253f1
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>
(cherry picked from commit 4f0ce001219b1e394dfe242d2b90907db72397ee)

include/linux/wait.h

@@ -346,6 +346,75 @@ do {									\
 	__ret;								\
 })
 
+/**
+ * wait_io_event_interruptible - sleep until an io condition gets true
+ * @wq: the waitqueue to wait on
+ * @condition: a C expression for the event to wait for
+ *
+ * The process is put to sleep (TASK_INTERRUPTIBLE) until the
+ * @condition evaluates to true or a signal is received.
+ * The @condition is checked each time the waitqueue @wq is woken up.
+ *
+ * wake_up() has to be called after changing any variable that could
+ * change the result of the wait condition.
+ *
+ * The function will return -ERESTARTSYS if it was interrupted by a
+ * signal and 0 if @condition evaluated to true.
+ */
+#define wait_io_event_interruptible(wq, condition)			\
+({									\
+	int __ret = 0;							\
+	if (!(condition))						\
+		__wait_io_event_interruptible(wq, condition, __ret);	\
+	__ret;								\
+})
+
+#define __wait_io_event_interruptible_timeout(wq, condition, ret)	\
+do {									\
+	DEFINE_WAIT(__wait);						\
+									\
+	for (;;) {							\
+		prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);	\
+		if (condition)						\
+			break;						\
+		if (!signal_pending(current)) {				\
+			ret = io_schedule_timeout(ret);			\
+			if (!ret)					\
+				break;					\
+			continue;					\
+		}							\
+		ret = -ERESTARTSYS;					\
+		break;							\
+	}								\
+	finish_wait(&wq, &__wait);					\
+} while (0)
+
+/**
+ * wait_io_event_interruptible_timeout - sleep until an io condition gets true or a timeout elapses
+ * @wq: the waitqueue to wait on
+ * @condition: a C expression for the event to wait for
+ * @timeout: timeout, in jiffies
+ *
+ * The process is put to sleep (TASK_INTERRUPTIBLE) until the
+ * @condition evaluates to true or a signal is received.
+ * The @condition is checked each time the waitqueue @wq is woken up.
+ *
+ * wake_up() has to be called after changing any variable that could
+ * change the result of the wait condition.
+ *
+ * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
+ * was interrupted by a signal, and the remaining jiffies otherwise
+ * if the condition evaluated to true before the timeout elapsed.
+ */
+
+#define wait_io_event_interruptible_timeout(wq, condition, timeout)	\
+({									\
+	long __ret = timeout;						\
+	if (!(condition))						\
+		__wait_io_event_interruptible_timeout(wq, condition, __ret); \
+	__ret;								\
+})
+
 #define __wait_event_interruptible_exclusive(wq, condition, ret)	\
 do {									\
 	DEFINE_WAIT(__wait);						\