gfs2: Add missing set_freezable() for freezable kthread

The kernel thread function gfs2_logd() and gfs2_quotad() invoke the
try_to_freeze() in its loop. But all the kernel threads are no-freezable
by default. So if we want to make a kernel thread to be freezable,
we have to invoke set_freezable() explicitly.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/log.c

@@ -1303,6 +1303,7 @@ int gfs2_logd(void *data)
 	struct gfs2_sbd *sdp = data;
 	unsigned long t = 1;
 
+	set_freezable();
 	while (!kthread_should_stop()) {
 		if (gfs2_withdrawing_or_withdrawn(sdp))
 			break;

fs/gfs2/quota.c

@@ -1583,6 +1583,7 @@ int gfs2_quotad(void *data)
 	unsigned long quotad_timeo = 0;
 	unsigned long t = 0;
 
+	set_freezable();
 	while (!kthread_should_stop()) {
 		if (gfs2_withdrawing_or_withdrawn(sdp))
 			break;