Re: [PATCH] loop sendfile retval

[Linus Torvalds]

On Mon, 11 Nov 2002, Hugh Dickins wrote:
>
> Buffer I/O error on device loop: its use of sendfile is (trivially)
> broken - retval is usually count done, only an error when negative.

Hmm.. Sendfile can return other values than "count" (ie a partial read).  
This return value change makes "do_lo_receive()" lose that information. As 
such, the new do_lo_receive() is weaker than the old one.

If fixing the loop code to handle partial IO is too nasty, then I would
suggest doing maybe something like

	if (ret > 0 && ret != bvec->bv_len)
		ret = -EIO;

which at least makes a partial IO an error instead of making it a success 
case (the code as-is seems to think that any non-negative return value 
means that the IO was fully successful).

> Nearby spinlocking clearly bogus, delete instead of remarking on it.

I'll apply the patch, it looks better than what is there now, but it might 
be worth fixing this _right_.

		Linus