Re: [PATCH net-next v5 04/16] ceph: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage()

[David Howells]

Ilya Dryomov <idryomov@xxxxxxxxx> wrote:

> > Btw, is it feasible to use con->v2.out_iter_sendpage to apply
> > MSG_SPLICE_PAGES to the iterator to be transmitted as a whole?  It seems
> > to be set depending on iterator type.
> 
> I'm not sure I understand what you mean by "transmitted as a whole".
> con->v2.out_iter_sendpage is set only when zerocopy is desired.  If the
> underlying data is not guaranteed to remain stable, zerocopy behavior
> is not safe.

I think I need to reinstate the per-page sendpage_ok() check here also -
though Al pointed out it isn't sufficiently exhaustive.  There are pages that
sendpage_ok() will return true on that you shouldn't be passing to sendpage().

I'll whip up a patch to partially revert this also.

David