fs: poll/select/recvmmsg: use timespec64 for timeout events

struct timespec is not y2038 safe.  Even though timespec might be
sufficient to represent timeouts, use struct timespec64 here as the plan
is to get rid of all timespec reference in the kernel.

The patch transitions the common functions: poll_select_set_timeout()
and select_estimate_accuracy() to use timespec64.  And, all the syscalls
that use these functions are transitioned in the same patch.

The restart block parameters for poll uses monotonic time.  Use
timespec64 here as well to assign timeout value.  This parameter in the
restart block need not change because this only holds the monotonic
timestamp at which timeout should occur.  And, unsigned long data type
should be big enough for this timestamp.

The system call interfaces will be handled in a separate series.

Compat interfaces need not change as timespec64 is an alias to struct
timespec on a 64 bit system.

Link: http://lkml.kernel.org/r/1461947989-21926-3-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 8a74a2a..10db912 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1583,15 +1583,15 @@
 	return ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0, false);
 }
 
-static inline struct timespec ep_set_mstimeout(long ms)
+static inline struct timespec64 ep_set_mstimeout(long ms)
 {
-	struct timespec now, ts = {
+	struct timespec64 now, ts = {
 		.tv_sec = ms / MSEC_PER_SEC,
 		.tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC),
 	};
 
-	ktime_get_ts(&now);
-	return timespec_add_safe(now, ts);
+	ktime_get_ts64(&now);
+	return timespec64_add_safe(now, ts);
 }
 
 /**
@@ -1621,11 +1621,11 @@
 	ktime_t expires, *to = NULL;
 
 	if (timeout > 0) {
-		struct timespec end_time = ep_set_mstimeout(timeout);
+		struct timespec64 end_time = ep_set_mstimeout(timeout);
 
 		slack = select_estimate_accuracy(&end_time);
 		to = &expires;
-		*to = timespec_to_ktime(end_time);
+		*to = timespec64_to_ktime(end_time);
 	} else if (timeout == 0) {
 		/*
 		 * Avoid the unnecessary trip to the wait queue loop, if the