btrfs: sink blocksize parameter to readahead_tree_block

All callers pass nodesize.

Signed-off-by: David Sterba <dsterba@suse.cz>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3096512..be9d7c6 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1073,12 +1073,12 @@
 	.set_page_dirty = btree_set_page_dirty,
 };
 
-void readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize)
+void readahead_tree_block(struct btrfs_root *root, u64 bytenr)
 {
 	struct extent_buffer *buf = NULL;
 	struct inode *btree_inode = root->fs_info->btree_inode;
 
-	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
+	buf = btrfs_find_create_tree_block(root, bytenr, root->nodesize);
 	if (!buf)
 		return;
 	read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,