f2fs: move flush tracepoint

This patch moves the tracepoint location for flush command.
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -426,6 +426,9 @@ static int submit_flush_wait(struct f2fs_sb_info *sbi)
 	int ret = __submit_flush_wait(sbi->sb->s_bdev);
 	int i;
 
+	trace_f2fs_issue_flush(sbi->sb, test_opt(sbi, NOBARRIER),
+					test_opt(sbi, FLUSH_MERGE));
+
 	if (sbi->s_ndevs && !ret) {
 		for (i = 1; i < sbi->s_ndevs; i++) {
 			ret = __submit_flush_wait(FDEV(i).bdev);
@@ -471,9 +474,6 @@ int f2fs_issue_flush(struct f2fs_sb_info *sbi)
 	struct flush_cmd_control *fcc = SM_I(sbi)->fcc_info;
 	struct flush_cmd cmd;
 
-	trace_f2fs_issue_flush(sbi->sb, test_opt(sbi, NOBARRIER),
-					test_opt(sbi, FLUSH_MERGE));
-
 	if (test_opt(sbi, NOBARRIER))
 		return 0;