I found the reason.

I referred:
https://dev.openwrt.org/ticket/16279

There is a missing in implentation of struct file_operations.iterate.
It misinterpret the return value of dir_emit().


There is no problem in yaffs_iterate() of git://www.aleph1.co.uk/yaffs2


Thanks for yaffs works.

> Now I'm trying YAFFS2 with the kernel builted from OpenWrt git trunk tree.
> Its kernel revision is 3.14.27 and target architechture is ARMv7.
> 
> The yaffs2 codes are based git commit:
> > Version: bc76682d93955cfb33051beb503ad9f8a5450578 (2013-12-03)
> 
> 
> When I tried creating 1024 files with the following script,
> the problem occurred.
> - Number of files listed with "find /mnt/TEMP -type f" is 1022.
> - file1.bin and file2.bin are lost.
> 
> It seems that number of d-entries in a sub directory is limitted up to 1024.
> (1024 - 1022 = 2, used for "." and "..")
> 
> 
> But, with linux-3.2.26, tbe above problem does not occur.
> 1024 files were created surely.
> 
> 
> Any suggestion to investigate this problem ?
> 
> 
> 
> 
> And, volume /mnt have enough rooms to create 1024 empty files.