start adding the tag to iov_iter

For now, just use the same thing we pass to ->direct_IO() - it's all
iovec-based at the moment.  Pass it explicitly to iov_iter_init() and
account for kvec vs. iovec in there, by the same kludge NFS ->direct_IO()
uses.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/splice.c b/fs/splice.c
index 9bc07d2..f99e420 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1548,7 +1548,7 @@
 	if (ret <= 0)
 		return ret;
 
-	iov_iter_init(&iter, iov, nr_segs, count, 0);
+	iov_iter_init(&iter, READ, iov, nr_segs, count);
 
 	sd.len = 0;
 	sd.total_len = count;