OS-1566 filesystem limits for ZFS datasets

*** 19,28 ****
--- 19,29 ----
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2012 by Delphix. All rights reserved.
+  * Copyright (c) 2012 Joyent, Inc. All rights reserved.
   */
  
  /*
   * DSL permissions are stored in a two level zap attribute
   * mechanism.   The first level identifies the "class" of
*** 519,529 ****
  
  /*
   * Check if user has requested permission.
   */
  int
! dsl_deleg_access_impl(dsl_dataset_t *ds, const char *perm, cred_t *cr)
  {
          dsl_dir_t *dd;
          dsl_pool_t *dp;
          void *cookie;
          int     error;
--- 520,531 ----
  
  /*
   * Check if user has requested permission.
   */
  int
! dsl_deleg_access_impl(dsl_dataset_t *ds, const char *perm, cred_t *cr,
!     boolean_t do_lock)
  {
          dsl_dir_t *dd;
          dsl_pool_t *dp;
          void *cookie;
          int     error;
*** 553,562 ****
--- 555,565 ----
          }
  
          avl_create(&permsets, perm_set_compare, sizeof (perm_set_t),
              offsetof(perm_set_t, p_node));
  
+         if (do_lock)
                  rw_enter(&dp->dp_config_rwlock, RW_READER);
          for (dd = ds->ds_dir; dd != NULL; dd = dd->dd_parent,
              checkflag = ZFS_DELEG_DESCENDENT) {
                  uint64_t zapobj;
                  boolean_t expanded;
*** 614,623 ****
--- 617,627 ----
                  if (error == 0)
                          goto success;
          }
          error = EPERM;
  success:
+         if (do_lock)
                  rw_exit(&dp->dp_config_rwlock);
  
          cookie = NULL;
          while ((setnode = avl_destroy_nodes(&permsets, &cookie)) != NULL)
                  kmem_free(setnode, sizeof (perm_set_t));
*** 633,643 ****
  
          error = dsl_dataset_hold(dsname, FTAG, &ds);
          if (error)
                  return (error);
  
!         error = dsl_deleg_access_impl(ds, perm, cr);
          dsl_dataset_rele(ds, FTAG);
  
          return (error);
  }
  
--- 637,647 ----
  
          error = dsl_dataset_hold(dsname, FTAG, &ds);
          if (error)
                  return (error);
  
!         error = dsl_deleg_access_impl(ds, perm, cr, B_TRUE);
          dsl_dataset_rele(ds, FTAG);
  
          return (error);
  }