Re: O_DIRECT wierd behavior..

[Linus Torvalds]

On Mon, 17 Dec 2001, Joel Becker wrote:
> 	IIRC, SUS states that if a fatal error occurred causing the
> partial write, that error will be returned on the next write or upon
> close().  Thus:
>
> 	/* Smart program handles partial writes */
> 	write(100k); = 50k
> 	write(remaining 50k); = -1/ENOSPC|EIO|etc

We do this, if the error is "hard". And "fatal" implies hardness, so we're
ok here.

> 	/* Dumb program doesn't handle partial write */
> 	write(100k); = 50k
> 	close(fd); = -1/EIO

But we're not doing this.

We'd have to save the error into the "struct file" to do the close thing.

Which is what NFS actually already does for other reasons (ie the
asynchronous nature of writes and thus IO errors), so generalizing it
might actually clean some stuff up (sockets have some of the same issues,
but socket semantics may be different enough that we do not want to have
common "error on next access" handling).

		Linus