Function vdev_raidz_io_start

freebsd/contrib/openzfs/module/zfs/vdev_raidz.c:1827–1856

* Start an IO operation on a RAIDZ VDev * * Outline: * - For write operations: * 1. Generate the parity data * 2. Create child zio write operations to each column's vdev, for both * data and parity. * 3. If the column skips any sectors for padding, create optional dummy * write zio children for those areas to improve aggregation continuity. * - For read operations: * 1.

 *      columns' VDevs as well.
 */
static void
vdev_raidz_io_start(zio_t *zio)
{
	vdev_t *vd = zio->io_vd;
	vdev_t *tvd = vd->vdev_top;
	vdev_raidz_t *vdrz = vd->vdev_tsd;
	raidz_map_t *rm;

	rm = vdev_raidz_map_alloc(zio, tvd->vdev_ashift,
	    vdrz->vd_logical_width, vdrz->vd_nparity);

	/*
	 * Until raidz expansion is implemented all maps for a raidz vdev
	 * contain a single row.
	 */
	ASSERT3U(rm->rm_nrows, ==, 1);
	raidz_row_t *rr = rm->rm_row[0];

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

	if (zio->io_type == ZIO_TYPE_WRITE) {
		vdev_raidz_io_start_write(zio, rr, tvd->vdev_ashift);
	} else {
		ASSERT(zio->io_type == ZIO_TYPE_READ);
		vdev_raidz_io_start_read(zio, rr);
	}

	zio_execute(zio);
}

/*
 * Report a checksum error for a child of a RAID-Z device.