get rid of pointless iov_length() in ->direct_IO()

all callers have iov_length(iter->iov, iter->nr_segs) == iov_iter_count(iter)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 5b184c7..28984baf 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -223,12 +223,13 @@
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 	struct inode *inode = mapping->host;
+	size_t count = iov_iter_count(iter);
 	ssize_t ret;
 
 	ret = blockdev_direct_IO(rw, iocb, inode, iter->iov, offset, iter->nr_segs,
 				  udf_get_block);
 	if (unlikely(ret < 0 && (rw & WRITE)))
-		udf_write_failed(mapping, offset + iov_length(iter->iov, iter->nr_segs));
+		udf_write_failed(mapping, offset + count);
 	return ret;
 }