3741 zfs needs better comments
Submitted by:   Will Andrews <willa@spectralogic.com>
Submitted by:   Justin Gibbs <justing@spectralogic.com>
Submitted by:   Alan Somers <alans@spectralogic.com>
Reviewed by:    Matthew Ahrens <mahrens@delphix.com>
Reviewed by:    Eric Schrock <eric.schrock@delphix.com>

*** 1012,1021 ****
--- 1012,1025 ----
          if (tx->tx_txg == 0)
                  return;
  
          txg_rele_to_quiesce(&tx->tx_txgh);
  
+         /*
+          * Walk the transaction's hold list, removing the hold on the
+          * associated dnode, and notifying waiters if the refcount drops to 0.
+          */
          for (txh = list_head(&tx->tx_holds); txh != tx->tx_needassign_txh;
              txh = list_next(&tx->tx_holds, txh)) {
                  dnode_t *dn = txh->txh_dnode;
  
                  if (dn == NULL)
*** 1124,1133 ****
--- 1128,1141 ----
  {
          dmu_tx_hold_t *txh;
  
          ASSERT(tx->tx_txg != 0);
  
+         /*
+          * Go through the transaction's hold list and remove holds on
+          * associated dnodes, notifying waiters if no holds remain.
+          */
          while (txh = list_head(&tx->tx_holds)) {
                  dnode_t *dn = txh->txh_dnode;
  
                  list_remove(&tx->tx_holds, txh);
                  kmem_free(txh, sizeof (dmu_tx_hold_t));