Function vdev_draid_map_alloc

freebsd/contrib/openzfs/module/zfs/vdev_draid.c:1301–1343

* Allocate the raidz mapping to be applied to the dRAID I/O. The parity * calculations for dRAID are identical to raidz however there are a few * differences in the layout. * * - dRAID always allocates a full stripe width. Any extra sectors due * this padding are zero filled and written to disk. They will be read * back during a scrub or repair operation since they are included in *

 *   the first group and the other at the start of the following group.
 */
static raidz_map_t *
vdev_draid_map_alloc(zio_t *zio)
{
	raidz_row_t *rr[2];
	uint64_t abd_offset = 0;
	uint64_t abd_size = zio->io_size;
	uint64_t io_offset = zio->io_offset;
	uint64_t size;
	int nrows = 1;

	size = vdev_draid_map_alloc_row(zio, &rr[0], io_offset,
	    abd_offset, abd_size);
	if (size < abd_size) {
		vdev_t *vd = zio->io_vd;

		io_offset += vdev_draid_asize(vd, size);
		abd_offset += size;
		abd_size -= size;
		nrows++;

		ASSERT3U(io_offset, ==, vdev_draid_group_to_offset(
		    vd, vdev_draid_offset_to_group(vd, io_offset)));
		ASSERT3U(abd_offset, <, zio->io_size);
		ASSERT3U(abd_size, !=, 0);

		size = vdev_draid_map_alloc_row(zio, &rr[1],
		    io_offset, abd_offset, abd_size);
		VERIFY3U(size, ==, abd_size);
	}

	raidz_map_t *rm;
	rm = kmem_zalloc(offsetof(raidz_map_t, rm_row[nrows]), KM_SLEEP);
	rm->rm_ops = vdev_raidz_math_get_ops();
	rm->rm_nrows = nrows;
	rm->rm_row[0] = rr[0];
	if (nrows == 2)
		rm->rm_row[1] = rr[1];

	zio->io_vsd = rm;
	zio->io_vsd_ops = &vdev_draid_vsd_ops;

	return (rm);
}

/*
 * Given an offset into a dRAID return the next group width aligned offset