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/btrfs/inode.c b/fs/btrfs/inode.c
index 686331f..e9a3ff8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8174,10 +8174,10 @@
 		wakeup = false;
 	}
 
-	ret = __blockdev_direct_IO(rw, iocb, inode,
-			BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev,
-			iter, offset, btrfs_get_blocks_direct, NULL,
-			btrfs_submit_direct, flags);
+	ret = __blockdev_direct_IO(iocb, inode,
+				   BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev,
+				   iter, offset, btrfs_get_blocks_direct, NULL,
+				   btrfs_submit_direct, flags);
 	if (rw & WRITE) {
 		current->journal_info = NULL;
 		if (ret < 0 && ret != -EIOCBQUEUED)