fs/btrfs/extent_map.c

680  * are split.
687 	struct extent_map *split;
711 	 * because we need to split those two extent maps at the boundaries.
713 	split = alloc_extent_map();
745 		 * In case we split the extent map, we want to preserve the
754 		 * split it, we can remove it directly.
763 			if (!split) {
764 				split = split2;
766 				if (!split)
769 			split->start = em->start;
770 			split->len = start - em->start;
773 				split->orig_start = em->orig_start;
774 				split->block_start = em->block_start;
777 					split->block_len = em->block_len;
779 					split->block_len = split->len;
780 				split->orig_block_len = max(split->block_len,
782 				split->ram_bytes = em->ram_bytes;
784 				split->orig_start = split->start;
785 				split->block_len = 0;
786 				split->block_start = em->block_start;
787 				split->orig_block_len = 0;
788 				split->ram_bytes = split->len;
791 			split->generation = gen;
792 			split->flags = flags;
793 			replace_extent_mapping(em_tree, em, split, modified);
794 			free_extent_map(split);
795 			split = split2;
799 			if (!split) {
800 				split = split2;
802 				if (!split)
805 			split->start = end;
806 			split->len = em_end - end;
807 			split->block_start = em->block_start;
808 			split->flags = flags;
809 			split->generation = gen;
812 				split->orig_block_len = max(em->block_len,
815 				split->ram_bytes = em->ram_bytes;
817 					split->block_len = em->block_len;
818 					split->orig_start = em->orig_start;
822 					split->block_len = split->len;
823 					split->block_start += diff;
824 					split->orig_start = em->orig_start;
827 				split->ram_bytes = split->len;
828 				split->orig_start = split->start;
829 				split->block_len = 0;
830 				split->orig_block_len = 0;
834 				replace_extent_mapping(em_tree, em, split,
839 				ret = add_extent_mapping(em_tree, split,
846 			free_extent_map(split);
847 			split = NULL;
860 			 *    maps for split operations, @split and @split2.
872 				ASSERT(!split);
892 	free_extent_map(split);
941  * This function is used when an ordered_extent needs to be split.