Function vdev_rebuild_range

freebsd/contrib/openzfs/module/zfs/vdev_rebuild.c:535–608

* Issues a rebuild I/O and takes care of rate limiting the number of queued * rebuild I/Os. The provided start and size must be properly aligned for the * top-level vdev type being rebuilt. */

 * top-level vdev type being rebuilt.
 */
static int
vdev_rebuild_range(vdev_rebuild_t *vr, uint64_t start, uint64_t size)
{
	uint64_t ms_id __maybe_unused = vr->vr_scan_msp->ms_id;
	vdev_t *vd = vr->vr_top_vdev;
	spa_t *spa = vd->vdev_spa;
	blkptr_t blk;

	ASSERT3U(ms_id, ==, start >> vd->vdev_ms_shift);
	ASSERT3U(ms_id, ==, (start + size - 1) >> vd->vdev_ms_shift);

	vr->vr_pass_bytes_scanned += size;
	vr->vr_rebuild_phys.vrp_bytes_scanned += size;

	/*
	 * Rebuild the data in this range by constructing a special block
	 * pointer.  It has no relation to any existing blocks in the pool.
	 * However, by disabling checksum verification and issuing a scrub IO
	 * we can reconstruct and repair any children with missing data.
	 */
	vdev_rebuild_blkptr_init(&blk, vd, start, size);
	uint64_t psize = BP_GET_PSIZE(&blk);

	if (!vdev_dtl_need_resilver(vd, &blk.blk_dva[0], psize, TXG_UNKNOWN))
		return (0);

	mutex_enter(&vr->vr_io_lock);

	/* Limit in flight rebuild I/Os */
	while (vr->vr_bytes_inflight >= vr->vr_bytes_inflight_max)
		cv_wait(&vr->vr_io_cv, &vr->vr_io_lock);

	vr->vr_bytes_inflight += psize;
	mutex_exit(&vr->vr_io_lock);

	dmu_tx_t *tx = dmu_tx_create_dd(spa_get_dsl(spa)->dp_mos_dir);
	VERIFY0(dmu_tx_assign(tx, TXG_WAIT));
	uint64_t txg = dmu_tx_get_txg(tx);

	spa_config_enter(spa, SCL_STATE_ALL, vd, RW_READER);
	mutex_enter(&vd->vdev_rebuild_lock);

	/* This is the first I/O for this txg. */
	if (vr->vr_scan_offset[txg & TXG_MASK] == 0) {
		vr->vr_scan_offset[txg & TXG_MASK] = start;
		dsl_sync_task_nowait(spa_get_dsl(spa),
		    vdev_rebuild_update_sync,
		    (void *)(uintptr_t)vd->vdev_id, tx);
	}

	/* When exiting write out our progress. */
	if (vdev_rebuild_should_stop(vd)) {
		mutex_enter(&vr->vr_io_lock);
		vr->vr_bytes_inflight -= psize;
		mutex_exit(&vr->vr_io_lock);
		spa_config_exit(vd->vdev_spa, SCL_STATE_ALL, vd);
		mutex_exit(&vd->vdev_rebuild_lock);
		dmu_tx_commit(tx);