Use the LZ4 algorithm to compress metadata when the corresponding feature is enabled

*** 25,34 ****
--- 25,35 ----
   * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
   * Copyright (c) 2014, Joyent, Inc. All rights reserved.
   * Copyright (c) 2013 by Delphix. All rights reserved.
   * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
   * Copyright (c) 2013 Steven Hartland. All rights reserved.
+  * Copyright (c) 2014, Nexenta Systems, Inc. All rights reserved.
   */
  
  /*
   * ZFS ioctls.
   *
*** 2451,2491 ****
                          (void) zfs_ioc_userspace_upgrade(zc);
                          kmem_free(zc, sizeof (zfs_cmd_t));
                  }
                  break;
          }
-         case ZFS_PROP_COMPRESSION:
-         {
-                 if (intval == ZIO_COMPRESS_LZ4) {
-                         spa_t *spa;
- 
-                         if ((err = spa_open(dsname, &spa, FTAG)) != 0)
-                                 return (err);
- 
-                         /*
-                          * Setting the LZ4 compression algorithm activates
-                          * the feature.
-                          */
-                         if (!spa_feature_is_active(spa,
-                             SPA_FEATURE_LZ4_COMPRESS)) {
-                                 if ((err = zfs_prop_activate_feature(spa,
-                                     SPA_FEATURE_LZ4_COMPRESS)) != 0) {
-                                         spa_close(spa, FTAG);
-                                         return (err);
-                                 }
-                         }
- 
-                         spa_close(spa, FTAG);
-                 }
-                 /*
-                  * We still want the default set action to be performed in the
-                  * caller, we only performed zfeature settings here.
-                  */
-                 err = -1;
-                 break;
-         }
- 
          default:
                  err = -1;
          }
  
          return (err);
--- 2452,2461 ----