This is what i was looking for.
we use SD card in the embedded system, was trying to make sure the data won't get corrupted.
But seems it causes plenty of delay when write data back to SD.
E.g. when we soft reset the board, we try to close all files, was hoping to save all data to SD.
After wait ~5 seconds, we poweroff.
But a lot of times when we boot up, the files are missing.
So our random guess is the ext4 is not writing back to SD and complete its task on time.
Thanks for your reply and we'll try it out.
Originally Posted by replica9000
Why is your ext4 filesystem on a journey?
You can mount an ext4 filesystem with the data=writeback option
/dev/sda1 / ext4 defaults,data=writeback 0 1