Re: [PATCH 05/16] Add io_uring IO interface

On 1/9/19 11:30 AM, Christoph Hellwig wrote:

On Wed, Jan 09, 2019 at 08:53:31AM -0700, Jens Axboe wrote:

quoted

quoted

quoted

+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.

OK, I see what you mean, so only supported the vectored version.
Probably makes more sense, I'll make the change.

-- 
Jens Axboe