cstyle fixes
dsl_dataset_set_fsid_guid should use ZFS_SPACE_CHECK_RESERVED
dsl_dataset_set_fsid_guid _check and _sync func declared static,
removed from dsl_dataset.h
rewrite unique_valid
6333 ZFS should let the user specify or modify the fsid_guid of a dataset

*** 97,106 ****
--- 97,121 ----
          mutex_exit(&unique_mtx);
  
          return (un->un_value);
  }
  
+ boolean_t
+ unique_valid(uint64_t value)
+ {
+         unique_t un_tofind;
+ 
+         un_tofind.un_value = value;
+ 
+         mutex_enter(&unique_mtx);
+         boolean_t rv = ((value & ~UNIQUE_MASK) == 0 &&
+             avl_find(&unique_avl, &un_tofind, NULL) == NULL);
+         mutex_exit(&unique_mtx);
+ 
+         return (rv);
+ }
+ 
  void
  unique_remove(uint64_t value)
  {
          unique_t un_tofind;
          unique_t *un;