return true;
 }
 
-static struct btrfs_free_space_op free_space_op = {
+static const struct btrfs_free_space_op free_space_op = {
        .recalc_thresholds      = recalculate_thresholds,
        .use_bitmap             = use_bitmap,
 };
 
        int total_bitmaps;
        int unit;
        u64 start;
-       struct btrfs_free_space_op *op;
+       const struct btrfs_free_space_op *op;
        void *private;
        struct mutex cache_writeout_mutex;
        struct list_head trimming_ranges;
 
        return true;
 }
 
-static struct btrfs_free_space_op free_ino_op = {
+static const struct btrfs_free_space_op free_ino_op = {
        .recalc_thresholds      = recalculate_thresholds,
        .use_bitmap             = use_bitmap,
 };
        return false;
 }
 
-static struct btrfs_free_space_op pinned_free_ino_op = {
+static const struct btrfs_free_space_op pinned_free_ino_op = {
        .recalc_thresholds      = pinned_recalc_thresholds,
        .use_bitmap             = pinned_use_bitmap,
 };
 
 static const struct address_space_operations btrfs_aops;
 static const struct address_space_operations btrfs_symlink_aops;
 static const struct file_operations btrfs_dir_file_operations;
-static struct extent_io_ops btrfs_extent_io_ops;
+static const struct extent_io_ops btrfs_extent_io_ops;
 
 static struct kmem_cache *btrfs_inode_cachep;
 struct kmem_cache *btrfs_trans_handle_cachep;
        .fsync          = btrfs_sync_file,
 };
 
-static struct extent_io_ops btrfs_extent_io_ops = {
+static const struct extent_io_ops btrfs_extent_io_ops = {
        .fill_delalloc = run_delalloc_range,
        .submit_bio_hook = btrfs_submit_bio_hook,
        .merge_bio_hook = btrfs_merge_bio_hook,
 
        int ret;
        u64 offset;
        u64 max_extent_size;
-       struct btrfs_free_space_op test_free_space_ops = {
+       const struct btrfs_free_space_op test_free_space_ops = {
                .recalc_thresholds = cache->free_space_ctl->op->recalc_thresholds,
                .use_bitmap = test_use_bitmap,
        };
-       struct btrfs_free_space_op *orig_free_space_ops;
+       const struct btrfs_free_space_op *orig_free_space_ops;
 
        test_msg("Running space stealing from bitmap to extent\n");