Re: [PATCH v2 08/17] {macvtap,tun}_get_user(): switch to iov_iter

On Tue, Feb 03, 2015 at 02:27:28PM +0000, Al Viro wrote:

On Tue, Feb 03, 2015 at 12:10:44PM +0200, Michael S. Tsirkin wrote:

quoted

Hmm does copy_from_iter actually modify the iovec?
If so, won't this break aio on tun/macvtap, by
reversing the effect of
commit 6f26c9a7555e5bcca3560919db9b852015077dae
    tun: fix tun_chr_aio_write so that aio works
?


Maybe we should change iovec_iter to avoid modifying the
underlying iovec?

iov_iter never changes the underlying iovec (or kvec, or bvec).
iter->iov_offset changes as you go and once you have consumed an
entire iovec element ->iov is incremented to point to the next one
(and ->iov_offset is reset to 0 at that point).  *Contents* of
iter->iov is never modified.

I see, I think I misread the code.
Thanks for the clarification.

-- 
MST