fs/btrfs/file.c

2088 	struct extent_map *hole_em;
2153 	hole_em = alloc_extent_map();
2154 	if (!hole_em) {
2158 		hole_em->start = offset;
2159 		hole_em->len = end - offset;
2160 		hole_em->ram_bytes = hole_em->len;
2161 		hole_em->orig_start = offset;
2163 		hole_em->block_start = EXTENT_MAP_HOLE;
2164 		hole_em->block_len = 0;
2165 		hole_em->orig_block_len = 0;
2166 		hole_em->generation = trans->transid;
2168 		ret = btrfs_replace_extent_map_range(inode, hole_em, true);
2169 		free_extent_map(hole_em);