+ if (dn->dn_next_nblkptr[txgoff]) {
+ /* this should only happen on a realloc */
+ ASSERT(dn->dn_allocated_txg == tx->tx_txg);
+ if (dn->dn_next_nblkptr[txgoff] > dnp->dn_nblkptr) {
+ /* zero the new blkptrs we are gaining */
+ bzero(dnp->dn_blkptr + dnp->dn_nblkptr,
+ sizeof (blkptr_t) *
+ (dn->dn_next_nblkptr[txgoff] - dnp->dn_nblkptr));
+#ifdef ZFS_DEBUG
+ } else {
+ int i;
+ ASSERT(dn->dn_next_nblkptr[txgoff] < dnp->dn_nblkptr);
+ /* the blkptrs we are losing better be unallocated */
+ for (i = dn->dn_next_nblkptr[txgoff];
+ i < dnp->dn_nblkptr; i++)
+ ASSERT(BP_IS_HOLE(&dnp->dn_blkptr[i]));
+#endif
+ }
+ mutex_enter(&dn->dn_mtx);
+ dnp->dn_nblkptr = dn->dn_next_nblkptr[txgoff];
+ dn->dn_next_nblkptr[txgoff] = 0;
+ mutex_exit(&dn->dn_mtx);
+ }
+