* Insert @em into @tree or perform a simple forward/backward merge with
* existing mappings. The extent_map struct passed in will be inserted
* into the tree directly, with an additional reference taken, or a
- * reference dropped if the merge attempt was successfull.
+ * reference dropped if the merge attempt was successful.
*/
int add_extent_mapping(struct extent_map_tree *tree,
struct extent_map *em)