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/ext4/inode.c b/fs/ext4/inode.c
index a3f4513..ec049c0 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3037,7 +3037,7 @@
 		ret = dax_do_io(rw, iocb, inode, iter, offset, get_block_func,
 				ext4_end_io_dio, dio_flags);
 	else
-		ret = __blockdev_direct_IO(rw, iocb, inode,
+		ret = __blockdev_direct_IO(iocb, inode,
 					   inode->i_sb->s_bdev, iter, offset,
 					   get_block_func,
 					   ext4_end_io_dio, NULL, dio_flags);