ext4: do not call FC trace event in ext4_fc_commit() if FS does not support FC

This just puts trace_ext4_fc_commit_start(sb) & ktime_get()
for measuring FC commit time, after the check of whether sb
supports JOURNAL_FAST_COMMIT or not.
Signed-off-by: NRitesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: NHarshad Shirwadkar <harshadshirwadkar@gmail.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/d53cf3e535924ec0a1eb41a560e96561b0727e7a.1647057583.git.riteshh@linux.ibm.comSigned-off-by: NTheodore Ts'o <tytso@mit.edu>

fs/ext4/fast_commit.c

@@ -1165,13 +1165,13 @@ int ext4_fc_commit(journal_t *journal, tid_t commit_tid)
 	int status = EXT4_FC_STATUS_OK, fc_bufs_before = 0;
 	ktime_t start_time, commit_time;
 
+	if (!test_opt2(sb, JOURNAL_FAST_COMMIT))
+		return jbd2_complete_transaction(journal, commit_tid);
+
 	trace_ext4_fc_commit_start(sb);
 
 	start_time = ktime_get();
 
-	if (!test_opt2(sb, JOURNAL_FAST_COMMIT))
-		return jbd2_complete_transaction(journal, commit_tid);
-
 restart_fc:
 	ret = jbd2_fc_begin_commit(journal, commit_tid);
 	if (ret == -EALREADY) {