On 8/24/20 6:54 PM, Al Viro wrote:
On Fri, Aug 21, 2020 at 09:20:54PM -0700, John Hubbard wrote:
Direct IO behavior:
ITER_IOVEC:
pin_user_pages_fast();
break;
ITER_KVEC: // already elevated page refcount, leave alone
ITER_BVEC: // already elevated page refcount, leave alone
ITER_PIPE: // just, no :)
Why? What's wrong with splice to O_DIRECT file?
Oh! I'll take a look. Is this the fs/splice.c stuff? I ruled this out early
mainly based on Christoph's comment in [1] ("ITER_PIPE is rejected іn the
direct I/O path"), but if it's supportable then I'll hook it up.
(As you can see, I'm still very much coming up to speed on the various things
that invoke iov_iter_get_pages*().)
[1] https://lore.kernel.org/kvm/20190724061750.GA19397@xxxxxxxxxxxxx/
thanks,
--
John Hubbard
NVIDIA
