484  * forward/backward merge with existing mappings.  The extent_map struct passed
637  * Helper for btrfs_get_extent.  Given an existing extent in the tree,
638  * the existing extent is the nearest extent to map_start,
643 					 struct extent_map *existing,  in merge_extent_mapping()  argument
656 	if (existing->start > map_start) {  in merge_extent_mapping()
657 		next = existing;  in merge_extent_mapping()
660 		prev = existing;  in merge_extent_mapping()
689  * a) Returning the existing extent in @em_in if @start is within the
690  *    existing em.
691  * b) Merge the existing extent with @em_in passed in.
716 		struct extent_map *existing;  in btrfs_add_extent_mapping()  local
718 		existing = btrfs_search_extent_mapping(&inode->extent_tree, start, len);  in btrfs_add_extent_mapping()
720 		trace_btrfs_handle_em_exist(fs_info, existing, em, start, len);  in btrfs_add_extent_mapping()
723 		 * existing will always be non-NULL, since there must be  in btrfs_add_extent_mapping()
726 		if (start >= existing->start &&  in btrfs_add_extent_mapping()
727 		    start < btrfs_extent_map_end(existing)) {  in btrfs_add_extent_mapping()
729 			*em_in = existing;  in btrfs_add_extent_mapping()
736 			 * The existing extent map is the one nearest to  in btrfs_add_extent_mapping()
739 			ret = merge_extent_mapping(inode, existing, em, start);  in btrfs_add_extent_mapping()
744 "extent map merge error existing [%llu, %llu) with em [%llu, %llu) start %llu",  in btrfs_add_extent_mapping()
745 					   existing->start, btrfs_extent_map_end(existing),  in btrfs_add_extent_mapping()
748 			btrfs_free_extent_map(existing);  in btrfs_add_extent_mapping()