Btrfs: hash the btree inode during  fill_super

The snapshot deletion  patches dropped this line, but the inode
needs to be hashed.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a0d41e7..f1e905f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1664,6 +1664,7 @@
 	memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
 	       sizeof(struct btrfs_key));
 	BTRFS_I(fs_info->btree_inode)->dummy_inode = 1;
+	insert_inode_hash(fs_info->btree_inode);
 
 	spin_lock_init(&fs_info->block_group_cache_lock);
 	fs_info->block_group_cache_tree.rb_node = NULL;