Re: Network/block layer race.

[David Miller <davem@davemloft.net>]

From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Date: Fri, 28 Mar 2008 23:56:13 +0300

> Hi.
> 
> On Fri, Mar 28, 2008 at 01:40:53PM -0700, David Miller (davem@davemloft.net) wrote:
> > If content protection is desired, higher level things are needed.
> > For example, SAMBA only uses sendfile() if the remote client
> > has an OP lock on the file in question.
> 
> What I propose is to inform sender about when page is transmitted and
> received on the other side via implicit acks, which are provided already
> by tcp, but is not provided to higher layer.
> We can use it for sendfile and thus do not require higher
> layer 'distributed' locks, i.e. sync some state between hosts to inform
> that data was succesfully received. Patch would be minimal, just export
> sock_wfree() and setup different skb destructor if sk_sock_data is
> provided, that will allow for special users (like the same samba) to use
> ->sendpage() path too (with some changes in the code of course, but that
> is worth whole page copying).

I'd have to see the patch, feel free to submit it :-)