Data lost in Android app for not write new checkpoint

[He YunLei <heyunlei@huawei.com>]

Hi all,
	Recently I did some test with f2fs on my Android phone, and found a problem
which I didn't know how to tackle it.
	I use my Android phone with /data partition formatted  by mkfs.f2fs. When the
phone just started, I check the f2fs status by reading the file /sys/kernel/debug/f2fs/status
in debugfs.
	
CP calls: 10
GC calls: 19 (BG: 19)
   - data segments : 19 (19)
   - node segments : 0 (0)

	We can see /data partition has done 10 times write_checkpoint since f2fs is mounted
on the phone, it also has triggered 19 times background GC.

******

Here I took some photos consecutively, and check the file /sys/kernel/debug/f2fs/status again

******

CP calls: 10
GC calls: 20 (BG: 20)
   - data segments : 20 (20)
   - node segments : 0 (0)
	
	there is no change in CP calls number and background GC doesn't write new checkpoint.
if then a sudden power failure or system crash occur, the photos will be lost when the phone
restart, and a sync before crash will avoid the data lost.
	I think this problem is bad for user experience of using Android phone with f2fs.
How do we deal with such situation? I wish you and other developers in this list could help
me in a correct way.

Thanks,
He



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