epoll: convert max_user_watches to long

On a 16TB machine, max_user_watches has an integer overflow.  Convert it
to use a long and handle the associated fallout.

Signed-off-by: Robin Holt <holt@sgi.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index abc527a..96e2321 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -683,7 +683,7 @@
 	atomic_t fanotify_listeners;
 #endif
 #ifdef CONFIG_EPOLL
-	atomic_t epoll_watches;	/* The number of file descriptors currently watched */
+	atomic_long_t epoll_watches; /* The number of file descriptors currently watched */
 #endif
 #ifdef CONFIG_POSIX_MQUEUE
 	/* protected by mq_lock	*/