673  * are split.
680 	struct extent_map *split;  in btrfs_drop_extent_map_range()  local
704 	 * because we need to split those two extent maps at the boundaries.  in btrfs_drop_extent_map_range()
706 	split = alloc_extent_map();  in btrfs_drop_extent_map_range()
738 		 * In case we split the extent map, we want to preserve the  in btrfs_drop_extent_map_range()
747 		 * split it, we can remove it directly.  in btrfs_drop_extent_map_range()
756 			if (!split) {  in btrfs_drop_extent_map_range()
757 				split = split2;  in btrfs_drop_extent_map_range()
759 				if (!split)  in btrfs_drop_extent_map_range()
762 			split->start = em->start;  in btrfs_drop_extent_map_range()
763 			split->len = start - em->start;  in btrfs_drop_extent_map_range()
766 				split->orig_start = em->orig_start;  in btrfs_drop_extent_map_range()
767 				split->block_start = em->block_start;  in btrfs_drop_extent_map_range()
770 					split->block_len = em->block_len;  in btrfs_drop_extent_map_range()
772 					split->block_len = split->len;  in btrfs_drop_extent_map_range()
773 				split->orig_block_len = max(split->block_len,  in btrfs_drop_extent_map_range()
775 				split->ram_bytes = em->ram_bytes;  in btrfs_drop_extent_map_range()
777 				split->orig_start = split->start;  in btrfs_drop_extent_map_range()
778 				split->block_len = 0;  in btrfs_drop_extent_map_range()
779 				split->block_start = em->block_start;  in btrfs_drop_extent_map_range()
780 				split->orig_block_len = 0;  in btrfs_drop_extent_map_range()
781 				split->ram_bytes = split->len;  in btrfs_drop_extent_map_range()
784 			split->generation = gen;  in btrfs_drop_extent_map_range()
785 			split->flags = flags;  in btrfs_drop_extent_map_range()
786 			replace_extent_mapping(em_tree, em, split, modified);  in btrfs_drop_extent_map_range()
787 			free_extent_map(split);  in btrfs_drop_extent_map_range()
788 			split = split2;  in btrfs_drop_extent_map_range()
792 			if (!split) {  in btrfs_drop_extent_map_range()
793 				split = split2;  in btrfs_drop_extent_map_range()
795 				if (!split)  in btrfs_drop_extent_map_range()
798 			split->start = end;  in btrfs_drop_extent_map_range()
799 			split->len = em_end - end;  in btrfs_drop_extent_map_range()
800 			split->block_start = em->block_start;  in btrfs_drop_extent_map_range()
801 			split->flags = flags;  in btrfs_drop_extent_map_range()
802 			split->generation = gen;  in btrfs_drop_extent_map_range()
805 				split->orig_block_len = max(em->block_len,  in btrfs_drop_extent_map_range()
808 				split->ram_bytes = em->ram_bytes;  in btrfs_drop_extent_map_range()
810 					split->block_len = em->block_len;  in btrfs_drop_extent_map_range()
811 					split->orig_start = em->orig_start;  in btrfs_drop_extent_map_range()
815 					split->block_len = split->len;  in btrfs_drop_extent_map_range()
816 					split->block_start += diff;  in btrfs_drop_extent_map_range()
817 					split->orig_start = em->orig_start;  in btrfs_drop_extent_map_range()
820 				split->ram_bytes = split->len;  in btrfs_drop_extent_map_range()
821 				split->orig_start = split->start;  in btrfs_drop_extent_map_range()
822 				split->block_len = 0;  in btrfs_drop_extent_map_range()
823 				split->orig_block_len = 0;  in btrfs_drop_extent_map_range()
827 				replace_extent_mapping(em_tree, em, split,  in btrfs_drop_extent_map_range()
832 				ret = add_extent_mapping(em_tree, split,  in btrfs_drop_extent_map_range()
839 			free_extent_map(split);  in btrfs_drop_extent_map_range()
840 			split = NULL;  in btrfs_drop_extent_map_range()
853 			 *    maps for split operations, @split and @split2.  in btrfs_drop_extent_map_range()
865 				ASSERT(!split);  in btrfs_drop_extent_map_range()
885 	free_extent_map(split);  in btrfs_drop_extent_map_range()
931  * Split off the first pre bytes from the extent_map at [start, start + len],
934  * This function is used when an ordered_extent needs to be split.