xfs: Don't wake the aild once per second

Now that the AIL push algorithm is traversal safe, we don't need a
watchdog function in the xfsaild to catch pushes that fail to make
progress. Remove the watchdog timeout and make pushes purely driven
by demand. This will remove the once-per-second wakeup that is seen
when the filesystem is idle and make laptop power misers happy.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 77414db..9f2e398 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -877,12 +877,11 @@
 {
 	struct xfs_ail	*ailp = data;
 	xfs_lsn_t	last_pushed_lsn = 0;
-	long		tout = 0;
+	long		tout = 0; /* milliseconds */
 
 	while (!kthread_should_stop()) {
-		if (tout)
-			schedule_timeout_interruptible(msecs_to_jiffies(tout));
-		tout = 1000;
+		schedule_timeout_interruptible(tout ?
+				msecs_to_jiffies(tout) : MAX_SCHEDULE_TIMEOUT);
 
 		/* swsusp */
 		try_to_freeze();