4188 assertion failed in dmu_tx_hold_free(): dn_datablkshift != 0
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>

*** 633,645 ****
                  int shift = dn->dn_datablkshift + dn->dn_indblkshift -
                      SPA_BLKPTRSHIFT;
                  uint64_t start = off >> shift;
                  uint64_t end = (off + len) >> shift;
  
-                 ASSERT(dn->dn_datablkshift != 0);
                  ASSERT(dn->dn_indblkshift != 0);
  
                  zio = zio_root(tx->tx_pool->dp_spa,
                      NULL, NULL, ZIO_FLAG_CANFAIL);
                  for (uint64_t i = start; i <= end; i++) {
                          uint64_t ibyte = i << shift;
                          err = dnode_next_offset(dn, 0, &ibyte, 2, 1, 0);
--- 633,652 ----
                  int shift = dn->dn_datablkshift + dn->dn_indblkshift -
                      SPA_BLKPTRSHIFT;
                  uint64_t start = off >> shift;
                  uint64_t end = (off + len) >> shift;
  
                  ASSERT(dn->dn_indblkshift != 0);
  
+                 /*
+                  * dnode_reallocate() can result in an object with indirect
+                  * blocks having an odd data block size.  In this case,
+                  * just check the single block.
+                  */
+                 if (dn->dn_datablkshift == 0)
+                         start = end = 0;
+ 
                  zio = zio_root(tx->tx_pool->dp_spa,
                      NULL, NULL, ZIO_FLAG_CANFAIL);
                  for (uint64_t i = start; i <= end; i++) {
                          uint64_t ibyte = i << shift;
                          err = dnode_next_offset(dn, 0, &ibyte, 2, 1, 0);