Function zil_sync

freebsd/contrib/openzfs/module/zfs/zil.c:3012–3091

* Called in syncing context to free committed log blocks and update log header. */

 * Called in syncing context to free committed log blocks and update log header.
 */
void
zil_sync(zilog_t *zilog, dmu_tx_t *tx)
{
	zil_header_t *zh = zil_header_in_syncing_context(zilog);
	uint64_t txg = dmu_tx_get_txg(tx);
	spa_t *spa = zilog->zl_spa;
	uint64_t *replayed_seq = &zilog->zl_replayed_seq[txg & TXG_MASK];
	lwb_t *lwb;

	/*
	 * We don't zero out zl_destroy_txg, so make sure we don't try
	 * to destroy it twice.
	 */
	if (spa_sync_pass(spa) != 1)
		return;

	mutex_enter(&zilog->zl_lock);

	ASSERT(zilog->zl_stop_sync == 0);

	if (*replayed_seq != 0) {
		ASSERT(zh->zh_replay_seq < *replayed_seq);
		zh->zh_replay_seq = *replayed_seq;
		*replayed_seq = 0;
	}

	if (zilog->zl_destroy_txg == txg) {
		blkptr_t blk = zh->zh_log;

		ASSERT(list_head(&zilog->zl_lwb_list) == NULL);

		bzero(zh, sizeof (zil_header_t));
		bzero(zilog->zl_replayed_seq, sizeof (zilog->zl_replayed_seq));

		if (zilog->zl_keep_first) {
			/*
			 * If this block was part of log chain that couldn't
			 * be claimed because a device was missing during
			 * zil_claim(), but that device later returns,
			 * then this block could erroneously appear valid.
			 * To guard against this, assign a new GUID to the new
			 * log chain so it doesn't matter what blk points to.
			 */
			zil_init_log_chain(zilog, &blk);
			zh->zh_log = blk;
		}
	}

	while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) {
		zh->zh_log = lwb->lwb_blk;
		if (lwb->lwb_buf != NULL || lwb->lwb_max_txg > txg)
			break;
		list_remove(&zilog->zl_lwb_list, lwb);
		zio_free(spa, txg, &lwb->lwb_blk);
		zil_free_lwb(zilog, lwb);

		/*
		 * If we don't have anything left in the lwb list then