Remove rw from {,__,do_}blockdev_direct_IO()

Most filesystems call through to these at some point, so we'll start
here.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index df9d6af..3cbeb1b 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -864,7 +864,7 @@
 		ret = dax_do_io(rw, iocb, inode, iter, offset, ext2_get_block,
 				NULL, DIO_LOCKING);
 	else
-		ret = blockdev_direct_IO(rw, iocb, inode, iter, offset,
+		ret = blockdev_direct_IO(iocb, inode, iter, offset,
 					 ext2_get_block);
 	if (ret < 0 && (rw & WRITE))
 		ext2_write_failed(mapping, offset + count);