On Wed, Jan 09, 2019 at 08:53:31AM -0700, Jens Axboe wrote:
> >> +static int io_setup_rw(int rw, const struct io_uring_iocb *iocb,
> >> + struct iovec **iovec, struct iov_iter *iter)
> >> +{
> >> + void __user *buf = (void __user *)(uintptr_t)iocb->addr;
> >> + size_t ret;
> >> +
> >> + ret = import_single_range(rw, buf, iocb->len, *iovec, iter);
> >> + *iovec = NULL;
> >> + return ret;
> >> +}
> >
> > Is there any point in supporting non-vectored operations here?
>
> Not sure I follow?
This version only supports non-vectored read and write, that is
the equivalent of pread/pwrite. Many AIO users really need vectored
operations, that is preadv/pwritev semantics indirecting through
a struct iovec array. The non-vectored version can be trivially
emulated using a vector of 1, which is what we do in the kernel
I/O stack everywhere. So I think we should just support the vectored
version here, and not the non-vectored one. See my io_uring branch
for the sketeched implementation.
