3740 Poor ZFS send / receive performance due to snapshot hold / release processing
Submitted by: Steven Hartland <steven.hartland@multiplay.co.uk>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>

@@ -24,10 +24,11 @@
  * Portions Copyright 2011 Martin Matuska
  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2012, 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.
  */
 
 /*
  * ZFS ioctls.
  *

@@ -4978,20 +4979,10 @@
  */
 /* ARGSUSED */
 static int
 zfs_ioc_release(const char *pool, nvlist_t *holds, nvlist_t *errlist)
 {
-        nvpair_t *pair;
-
-        /*
-         * The release may cause the snapshot to be destroyed; make sure it
-         * is not mounted.
-         */
-        for (pair = nvlist_next_nvpair(holds, NULL); pair != NULL;
-            pair = nvlist_next_nvpair(holds, pair))
-                zfs_unmount_snap(nvpair_name(pair));
-
         return (dsl_dataset_user_release(holds, errlist));
 }
 
 /*
  * inputs: