f2fs: remove unnecessary gc option check and balance_fs

 1. If f2fs is mounted with background_gc_off option, checking
    BG_GC is not redundant.
 2. f2fs_balance_fs is checked in f2fs_gc, so this is also redundant.
Signed-off-by: NChangman Lee <cm224.lee@samsung.com>
Signed-off-by: NNamjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: NAmit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: NJaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/gc.c

@@ -49,11 +49,6 @@ static int gc_thread_func(void *data)
 			continue;
 		}
 
-		f2fs_balance_fs(sbi);
-
-		if (!test_opt(sbi, BG_GC))
-			continue;
-
 		/*
 		 * [GC triggering condition]
 		 * 0. GC is not conducted currently.
@@ -96,6 +91,8 @@ int start_gc_thread(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_gc_kthread *gc_th;
 
+	if (!test_opt(sbi, BG_GC))
+		return 0;
 	gc_th = kmalloc(sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
 	if (!gc_th)
 		return -ENOMEM;