Function vdev_raidz_need_resilver

freebsd/contrib/openzfs/module/zfs/vdev_raidz.c:2573–2611

* Determine if any portion of the provided block resides on a child vdev * with a dirty DTL and therefore needs to be resilvered. The function * assumes that at least one DTL is dirty which implies that full stripe * width blocks must be resilvered. */

 * width blocks must be resilvered.
 */
static boolean_t
vdev_raidz_need_resilver(vdev_t *vd, const dva_t *dva, size_t psize,
    uint64_t phys_birth)
{
	vdev_raidz_t *vdrz = vd->vdev_tsd;
	uint64_t dcols = vd->vdev_children;
	uint64_t nparity = vdrz->vd_nparity;
	uint64_t ashift = vd->vdev_top->vdev_ashift;
	/* The starting RAIDZ (parent) vdev sector of the block. */
	uint64_t b = DVA_GET_OFFSET(dva) >> ashift;
	/* The zio's size in units of the vdev's minimum sector size. */
	uint64_t s = ((psize - 1) >> ashift) + 1;
	/* The first column for this stripe. */
	uint64_t f = b % dcols;

	/* Unreachable by sequential resilver. */
	ASSERT3U(phys_birth, !=, TXG_UNKNOWN);

	if (!vdev_dtl_contains(vd, DTL_PARTIAL, phys_birth, 1))
		return (B_FALSE);

	if (s + nparity >= dcols)
		return (B_TRUE);

	for (uint64_t c = 0; c < s + nparity; c++) {
		uint64_t devidx = (f + c) % dcols;
		vdev_t *cvd = vd->vdev_child[devidx];

		/*
		 * dsl_scan_need_resilver() already checked vd with
		 * vdev_dtl_contains(). So here just check cvd with
		 * vdev_dtl_empty(), cheaper and a good approximation.
		 */
		if (!vdev_dtl_empty(cvd, DTL_PARTIAL))
			return (B_TRUE);
	}

	return (B_FALSE);
}

static void
vdev_raidz_xlate(vdev_t *cvd, const range_seg64_t *logical_rs,