md: remove special meaning of ->quiesce(.., 2)

The '2' argument means "wake up anything that is waiting".
This is an inelegant part of the design and was added
to help support management of suspend_lo/suspend_hi setting.
Now that suspend_lo/hi is managed in mddev_suspend/resume,
that need is gone.
These is still a couple of places where we call 'quiesce'
with an argument of '2', but they can safely be changed to
call ->quiesce(.., 1); ->quiesce(.., 0) which
achieve the same result at the small cost of pausing IO
briefly.

This removes a small "optimization" from suspend_{hi,lo}_store,
but it isn't clear that optimization served a useful purpose.
The code now is a lot clearer.

Suggested-by: Shaohua Li <shli@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index b0de5b5..615f677 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3828,18 +3828,14 @@ static void raid10_free(struct mddev *mddev, void *priv)
 	kfree(conf);
 }
 
-static void raid10_quiesce(struct mddev *mddev, int state)
+static void raid10_quiesce(struct mddev *mddev, int quiesce)
 {
 	struct r10conf *conf = mddev->private;
 
-	switch(state) {
-	case 1:
+	if (quiesce)
 		raise_barrier(conf, 0);
-		break;
-	case 0:
+	else
 		lower_barrier(conf);
-		break;
-	}
 }
 
 static int raid10_resize(struct mddev *mddev, sector_t sectors)