MFV r251644:

Poor ZFS send / receive performance due to snapshot
hold / release processing (by smh@)

Illumos ZFS issues:
  3740 Poor ZFS send / receive performance due to snapshot
       hold / release processing

MFC after:      2 weeks

1 files changed, 15 insertions, 3 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_pool.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_pool.c
index cc2631e..d7949e8 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_pool.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_pool.c
@@ -21,6 +21,7 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2013 by Delphix. All rights reserved.
+ * Copyright (c) 2013 Steven Hartland. All rights reserved.
  */
 
 #include <sys/dsl_pool.h>
@@ -856,23 +857,34 @@ dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
 	zap_cursor_t zc;
 	objset_t *mos = dp->dp_meta_objset;
 	uint64_t zapobj = dp->dp_tmp_userrefs_obj;
+	nvlist_t *holds;
 
 	if (zapobj == 0)
 		return;
 	ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
 
+	holds = fnvlist_alloc();
+
 	for (zap_cursor_init(&zc, mos, zapobj);
 	    zap_cursor_retrieve(&zc, &za) == 0;
 	    zap_cursor_advance(&zc)) {
 		char *htag;
-		uint64_t dsobj;
+		nvlist_t *tags;
 
 		htag = strchr(za.za_name, '-');
 		*htag = '\0';
 		++htag;
-		dsobj = strtonum(za.za_name, NULL);
-		dsl_dataset_user_release_tmp(dp, dsobj, htag);
+		if (nvlist_lookup_nvlist(holds, za.za_name, &tags) != 0) {
+			tags = fnvlist_alloc();
+			fnvlist_add_boolean(tags, htag);
+			fnvlist_add_nvlist(holds, za.za_name, tags);
+			fnvlist_free(tags);
+		} else {
+			fnvlist_add_boolean(tags, htag);
+		}
 	}
+	dsl_dataset_user_release_tmp(dp, holds);
+	fnvlist_free(holds);
 	zap_cursor_fini(&zc);
 }