I found this bug in 2.5.10 first. And caused ext2 FS corruption.
We are porting Linux to PC-9801 architecture (made by NEC Japan).
It has PIO ONLY IDE I/F. So please check PIO mode too.

It was introduced in 2.5.9 and still exists in 2.5.13, and caused
superblock corruption for Andries.  This fixes it.