Re: O_DIRECT wierd behavior..

[Hugh Dickins]

On Mon, 17 Dec 2001, Andrea Arcangeli wrote:
> 
> I'm unsure (it's basically a matter of API, not something a kernel
> developer can choose liberally), and the SuSv2 is not saying anything about
> O_SYNC failures in the write(2) manapge, but I guess it would be at
> least saner to put the "pos" backwards if we fail osync but we just
> written something (so if we previously advanced pos).

I don't have references to back me up, don't take my word for it:
but I'm sure that the correct behaviour for a partially successful
read or write in any UNIX is that it return the count done, O_SYNC
or not, and file position should match that count; only when none
has been done is -1 returned with errno set.  Most implementations will
get this wrong in one corner or another, but that's how it should be.

Hugh