396  * existing mappings.  The extent_map struct passed in will be inserted
538  * Helper for btrfs_get_extent.  Given an existing extent in the tree,
539  * the existing extent is the nearest extent to map_start,
544 					 struct extent_map *existing,  in merge_extent_mapping()  argument
556 	if (existing->start > map_start) {  in merge_extent_mapping()
557 		next = existing;  in merge_extent_mapping()
560 		prev = existing;  in merge_extent_mapping()
593  * a) Returning the existing extent in @em_in if @start is within the
594  *    existing em.
595  * b) Merge the existing extent with @em_in passed in.
613 		struct extent_map *existing;  in btrfs_add_extent_mapping()  local
617 		existing = search_extent_mapping(em_tree, start, len);  in btrfs_add_extent_mapping()
619 		trace_btrfs_handle_em_exist(fs_info, existing, em, start, len);  in btrfs_add_extent_mapping()
622 		 * existing will always be non-NULL, since there must be  in btrfs_add_extent_mapping()
625 		if (start >= existing->start &&  in btrfs_add_extent_mapping()
626 		    start < extent_map_end(existing)) {  in btrfs_add_extent_mapping()
628 			*em_in = existing;  in btrfs_add_extent_mapping()
635 			 * The existing extent map is the one nearest to  in btrfs_add_extent_mapping()
638 			ret = merge_extent_mapping(em_tree, existing,  in btrfs_add_extent_mapping()
644 "unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",  in btrfs_add_extent_mapping()
645 					  ret, existing->start, existing->len,  in btrfs_add_extent_mapping()
648 			free_extent_map(existing);  in btrfs_add_extent_mapping()