> > how about attached one?
> > it introduces third level nested buf so that we can get error via B_ERROR.
> 
> Is using `struct buf' here (especially in the interface of GOP_WRITE)
> really the right thing?  Actually, only keeping error and
> synchronizing is necessary.

sure.  I agree that struct buf here is overkill.
maybe we should have stripped version of struct buf.

YAMAMOTO Takashi