iov_iter: set nr_segs = 1 for ITER_UBUF

To avoid needing to check if a given user backed iov_iter is of type
ITER_IOVEC or ITER_UBUF, set the number of segments for the ITER_UBUF
case to 1 as we're carrying a single segment.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 7f585ce..5dbd2dc 100644 (file)
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -355,7 +355,8 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
                .user_backed = true,
                .data_source = direction,
                .ubuf = buf,
-               .count = count
+               .count = count,
+               .nr_segs = 1
        };
 }
 /* Flags for iov_iter_get/extract_pages*() */