f2fs: run fstrim asynchronously if runtime discard is on

index bef74d628f66..b1e58b10425f 100644
@@ -2439,9 +2439,18 @@ int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
 
 	__init_discard_policy(sbi, &dpolicy, DPOLICY_FSTRIM, cpc.trim_minlen);
 	__issue_discard_cmd_range(sbi, &dpolicy, start_block, end_block);
-	trimmed = __wait_discard_cmd_range(sbi, &dpolicy,
+
+	/*
+	 * We filed discard candidates, but actually we don't need to wait for
+	 * all of them, since they'll be issued in idle time along with runtime
+	 * discard option. User configuration looks like using runtime discard
+	 * or periodic fstrim instead of it.
+	 */
+	if (!test_opt(sbi, DISCARD)) {
+		trimmed = __wait_discard_cmd_range(sbi, &dpolicy,
 					start_block, end_block);
-	range->len = F2FS_BLK_TO_BYTES(trimmed);
+		range->len = F2FS_BLK_TO_BYTES(trimmed);
+	}
 out:
 	return err;
 }