f2fs: fix block address for __check_sit_bitmap

Should use lstart (logical start address) instead of start (in dev) here.
This fixes a bug in multi-device scenarios.
Signed-off-by: Qiuyang Sun <sunqiuyang@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -1151,7 +1151,7 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
 		list_move_tail(&dc->list, wait_list);
 
 		/* sanity check on discard range */
-		__check_sit_bitmap(sbi, start, start + len);
+		__check_sit_bitmap(sbi, lstart, lstart + len);
 
 		bio->bi_private = dc;
 		bio->bi_end_io = f2fs_submit_discard_endio;