f2fs: stop all the operations by cp_error flag

This patch replaces to use cp_error flag instead of RDONLY for quota off.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index c56e3ee..272625a 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -859,6 +859,9 @@
 	struct f2fs_sb_info *sbi = F2FS_SB(sb);
 	int err = 0;
 
+	if (unlikely(f2fs_cp_error(sbi)))
+		return 0;
+
 	trace_f2fs_sync_fs(sb, sync);
 
 	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))