f2fs: Use wait_event_freezable_timeout() for freezable kthread

A freezable kernel thread can enter frozen state during freezing by
either calling try_to_freeze() or using wait_event_freezable() and its
variants. So for the following snippet of code in a kernel thread loop:
  wait_event_interruptible_timeout();
  try_to_freeze();

We can change it to a simple wait_event_freezable_timeout() and then
eliminate the function calls to try_to_freeze() and freezing().

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: haokexin

fs/f2fs/gc.c

@@ -46,8 +46,8 @@ static int gc_thread_func(void *data)
 	do {
 		bool sync_mode, foreground = false;
 
-		wait_event_interruptible_timeout(*wq,
-				kthread_should_stop() || freezing(current) ||
+		wait_event_freezable_timeout(*wq,
+				kthread_should_stop() ||
 				waitqueue_active(fggc_wq) ||
 				gc_th->gc_wake,
 				msecs_to_jiffies(wait_ms));
@@ -59,7 +59,7 @@ static int gc_thread_func(void *data)
 		if (gc_th->gc_wake)
 			gc_th->gc_wake = false;
 
-		if (try_to_freeze() || f2fs_readonly(sbi->sb)) {
+		if (f2fs_readonly(sbi->sb)) {
 			stat_other_skip_bggc_count(sbi);
 			continue;
 		}

fs/f2fs/segment.c

@@ -1887,9 +1887,8 @@ static int issue_discard_thread(void *data)
 	set_freezable();
 
 	do {
-		wait_event_interruptible_timeout(*q,
-				kthread_should_stop() || freezing(current) ||
-				dcc->discard_wake,
+		wait_event_freezable_timeout(*q,
+				kthread_should_stop() || dcc->discard_wake,
 				msecs_to_jiffies(wait_ms));
 
 		if (sbi->gc_mode == GC_URGENT_HIGH ||
@@ -1907,8 +1906,6 @@ static int issue_discard_thread(void *data)
 		if (atomic_read(&dcc->queued_discard))
 			__wait_all_discard_cmd(sbi, NULL);
 
-		if (try_to_freeze())
-			continue;
 		if (f2fs_readonly(sbi->sb))
 			continue;
 		if (kthread_should_stop())