Illumos #3740

3740 Poor ZFS send / receive performance due to snapshot
     hold / release processing
Reviewed by: Matthew Ahrens <[email protected]>
Approved by: Christopher Siden <[email protected]>

References:
  https://www.illumos.org/issues/3740
  illumos/illumos-gate@a7a845e4bf22fd1b2a284729ccd95c7370a0438c

Ported-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #1775

Porting notes:

1. 13fe019870c8779bf2f5b3ff731b512cf89133ef introduced a merge conflict
   in dsl_dataset_user_release_tmp where some variables were moved
   outside of the preprocessor directive.

2. dea9dfefdd747534b3846845629d2200f0616dad made the previous merge
   conflict worse by switching KM_SLEEP to KM_PUSHPAGE. This is notable
   because this commit refactors the code, adding a new KM_SLEEP
   allocation. It is not clear to me whether this should be converted
   to KM_PUSHPAGE.

3. We had a merge conflict in libzfs_sendrecv.c because of copyright
   notices.

4. Several small C99 compatibility fixed were made.

3 files changed, 6 insertions, 5 deletions

diff --git a/include/libzfs.h b/include/libzfs.h
index c212a0c05..5fabcb1b1 100644
--- a/include/libzfs.h
+++ b/include/libzfs.h
@@ -24,6 +24,7 @@
  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
  * Copyright (c) 2012 by Delphix. All rights reserved.
  * Copyright (c) 2012, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2013 Steven Hartland. All rights reserved.
  */
 
 #ifndef	_LIBZFS_H
@@ -614,7 +615,8 @@ extern int zfs_send(zfs_handle_t *, const char *, const char *,
 
 extern int zfs_promote(zfs_handle_t *);
 extern int zfs_hold(zfs_handle_t *, const char *, const char *,
-    boolean_t, boolean_t, int);
+    boolean_t, int);
+extern int zfs_hold_nvl(zfs_handle_t *, int, nvlist_t *);
 extern int zfs_release(zfs_handle_t *, const char *, const char *, boolean_t);
 extern int zfs_get_holds(zfs_handle_t *, nvlist_t **);
 extern uint64_t zvol_volsize_to_reservation(uint64_t, nvlist_t *);
diff --git a/include/sys/dsl_dataset.h b/include/sys/dsl_dataset.h
index 494f11b90..725f0d233 100644
--- a/include/sys/dsl_dataset.h
+++ b/include/sys/dsl_dataset.h
@@ -22,6 +22,7 @@
  * Copyright (c) 2005, 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.
+ * Copyright (c) 2013 Steven Hartland. All rights reserved.
  */
 
 #ifndef	_SYS_DSL_DATASET_H
@@ -187,8 +188,6 @@ int dsl_dataset_own_obj(struct dsl_pool *dp, uint64_t dsobj,
 void dsl_dataset_disown(dsl_dataset_t *ds, void *tag);
 void dsl_dataset_name(dsl_dataset_t *ds, char *name);
 boolean_t dsl_dataset_tryown(dsl_dataset_t *ds, void *tag);
-void dsl_register_onexit_hold_cleanup(dsl_dataset_t *ds, const char *htag,
-    minor_t minor);
 uint64_t dsl_dataset_create_sync(dsl_dir_t *pds, const char *lastname,
     dsl_dataset_t *origin, uint64_t flags, cred_t *, dmu_tx_t *);
 uint64_t dsl_dataset_create_sync_dd(dsl_dir_t *dd, dsl_dataset_t *origin,
diff --git a/include/sys/dsl_userhold.h b/include/sys/dsl_userhold.h
index 56c6c8f47..071aeb86d 100644
--- a/include/sys/dsl_userhold.h
+++ b/include/sys/dsl_userhold.h
@@ -23,6 +23,7 @@
  * Copyright (c) 2005, 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.
+ * Copyright (c) 2013 Steven Hartland. All rights reserved.
  */
 
 #ifndef	_SYS_DSL_USERHOLD_H
@@ -43,8 +44,7 @@ int dsl_dataset_user_hold(nvlist_t *holds, minor_t cleanup_minor,
     nvlist_t *errlist);
 int dsl_dataset_user_release(nvlist_t *holds, nvlist_t *errlist);
 int dsl_dataset_get_holds(const char *dsname, nvlist_t *nvl);
-void dsl_dataset_user_release_tmp(struct dsl_pool *dp, uint64_t dsobj,
-    const char *htag);
+void dsl_dataset_user_release_tmp(struct dsl_pool *dp, nvlist_t *holds);
 int dsl_dataset_user_hold_check_one(struct dsl_dataset *ds, const char *htag,
     boolean_t temphold, struct dmu_tx *tx);
 void dsl_dataset_user_hold_sync_one(struct dsl_dataset *ds, const char *htag,