OpenZFS 8600 - ZFS channel programs - snapshot

Authored by: Chris Williamson <chris.williamson@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Ported-by: Don Brady <don.brady@delphix.com>

ZFS channel programs should be able to create snapshots.
In addition to the base snapshot functionality, this entails extra
logic to handle edge cases which were formerly not possible, such as
creating then destroying a snapshot in the same transaction sync.

OpenZFS-issue: https://www.illumos.org/issues/8600
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/68089b8b

include/sys/dsl_dataset.h

@@ -252,6 +252,13 @@ typedef struct dsl_dataset_rollback_arg {
 	nvlist_t *ddra_result;
 } dsl_dataset_rollback_arg_t;
 
+typedef struct dsl_dataset_snapshot_arg {
+	nvlist_t *ddsa_snaps;
+	nvlist_t *ddsa_props;
+	nvlist_t *ddsa_errors;
+	cred_t *ddsa_cr;
+} dsl_dataset_snapshot_arg_t;
+
 /*
  * The max length of a temporary tag prefix is the number of hex digits
  * required to express UINT64_MAX plus one for the hyphen.
@@ -296,6 +303,8 @@ uint64_t dsl_dataset_create_sync(dsl_dir_t *pds, const char *lastname,
     struct dsl_crypto_params *, dmu_tx_t *);
 uint64_t dsl_dataset_create_sync_dd(dsl_dir_t *dd, dsl_dataset_t *origin,
     struct dsl_crypto_params *dcp, uint64_t flags, dmu_tx_t *tx);
+void dsl_dataset_snapshot_sync(void *arg, dmu_tx_t *tx);
+int dsl_dataset_snapshot_check(void *arg, dmu_tx_t *tx);
 int dsl_dataset_snapshot(nvlist_t *snaps, nvlist_t *props, nvlist_t *errors);
 void dsl_dataset_promote_sync(void *arg, dmu_tx_t *tx);
 int dsl_dataset_promote_check(void *arg, dmu_tx_t *tx);

include/sys/zcp.h

@@ -14,7 +14,7 @@
  */
 
 /*
- * Copyright (c) 2016 by Delphix. All rights reserved.
+ * Copyright (c) 2016, 2017 by Delphix. All rights reserved.
  */
 
 #ifndef _SYS_ZCP_H
@@ -137,8 +137,6 @@ typedef struct zcp_lib_info {
 	const zcp_arg_t kwargs[2];
 } zcp_lib_info_t;
 
-int zcp_nvlist_to_lua(lua_State *, nvlist_t *, char *, int);
-
 #ifdef	__cplusplus
 }
 #endif

lib/libzfs_core/libzfs_core.c

@@ -20,7 +20,7 @@
  */
 
 /*
- * Copyright (c) 2012, 2016 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2017 Datto Inc.
  * Copyright 2017 RackTop Systems.
@@ -146,7 +146,12 @@ lzc_ioctl(zfs_ioc_t ioc, const char *name,
 
 	if (resultp != NULL) {
 		*resultp = NULL;
+		if (ioc == ZFS_IOC_CHANNEL_PROGRAM) {
+			zc.zc_nvlist_dst_size = fnvlist_lookup_uint64(source,
+			    ZCP_ARG_MEMLIMIT);
+		} else {
 			zc.zc_nvlist_dst_size = MAX(size * 2, 128 * 1024);
+		}
 		zc.zc_nvlist_dst = (uint64_t)(uintptr_t)
 		    malloc(zc.zc_nvlist_dst_size);
 		if (zc.zc_nvlist_dst == (uint64_t)0) {
@@ -160,7 +165,7 @@ lzc_ioctl(zfs_ioc_t ioc, const char *name,
 		 * If ioctl exited with ENOMEM, we retry the ioctl after
 		 * increasing the size of the destination nvlist.
 		 *
-		 * Channel programs that exit with ENOMEM probably ran over the
+		 * Channel programs that exit with ENOMEM ran over the
 		 * lua memory sandbox; they should not be retried.
 		 */
 		if (errno == ENOMEM && resultp != NULL &&

man/man8/zfs-program.8

@@ -372,6 +372,18 @@ filesystem (string)
 .Bd -ragged -compact -offset "xxxx"
 Filesystem to rollback.
 .Ed
+.It Em zfs.sync.snapshot(dataset)
+Create a snapshot of a filesystem.
+Returns 0 if the snapshot was successfully created,
+and a nonzero error code otherwise.
+.Pp
+Note: Taking a snapshot will fail on any pool older than legacy version 27.
+To enable taking snapshots from ZCP scripts, the pool must be upgraded.
+.Pp
+dataset (string)
+.Bd -ragged -compact -offset "xxxx"
+Name of snapshot to create.
+.Ed
 .El
 .It Sy zfs.check submodule
 For each function in the zfs.sync submodule, there is a corresponding zfs.check
@@ -392,6 +404,7 @@ The available zfs.check functions are:
 .It Em zfs.check.destroy(dataset, [defer=true|false])
 .It Em zfs.check.promote(dataset)
 .It Em zfs.check.rollback(filesystem)
+.It Em zfs.check.snapshot(dataset)
 .El
 .It Sy zfs.list submodule
 The zfs.list submodule provides functions for iterating over datasets and

module/zfs/dsl_dataset.c

@@ -1140,13 +1140,6 @@ dsl_dataset_snapshot_reserve_space(dsl_dataset_t *ds, dmu_tx_t *tx)
 	return (0);
 }
 
-typedef struct dsl_dataset_snapshot_arg {
-	nvlist_t *ddsa_snaps;
-	nvlist_t *ddsa_props;
-	nvlist_t *ddsa_errors;
-	cred_t *ddsa_cr;
-} dsl_dataset_snapshot_arg_t;
-
 int
 dsl_dataset_snapshot_check_impl(dsl_dataset_t *ds, const char *snapname,
     dmu_tx_t *tx, boolean_t recv, uint64_t cnt, cred_t *cr)
@@ -1206,7 +1199,7 @@ dsl_dataset_snapshot_check_impl(dsl_dataset_t *ds, const char *snapname,
 	return (0);
 }
 
-static int
+int
 dsl_dataset_snapshot_check(void *arg, dmu_tx_t *tx)
 {
 	dsl_dataset_snapshot_arg_t *ddsa = arg;
@@ -1486,7 +1479,7 @@ dsl_dataset_snapshot_sync_impl(dsl_dataset_t *ds, const char *snapname,
 	spa_history_log_internal_ds(ds->ds_prev, "snapshot", tx, "");
 }
 
-static void
+void
 dsl_dataset_snapshot_sync(void *arg, dmu_tx_t *tx)
 {
 	dsl_dataset_snapshot_arg_t *ddsa = arg;

module/zfs/zcp.c

@@ -14,7 +14,7 @@
  */
 
 /*
- * Copyright (c) 2016 by Delphix. All rights reserved.
+ * Copyright (c) 2016, 2017 by Delphix. All rights reserved.
  */
 
 /*
@@ -106,10 +106,15 @@
 #define	KM_NORMALPRI	0
 #endif
 
+#define	ZCP_NVLIST_MAX_DEPTH 20
+
 uint64_t zfs_lua_check_instrlimit_interval = 100;
 uint64_t zfs_lua_max_instrlimit = ZCP_MAX_INSTRLIMIT;
 uint64_t zfs_lua_max_memlimit = ZCP_MAX_MEMLIMIT;
 
+/*
+ * Forward declarations for mutually recursive functions
+ */
 static int zcp_nvpair_value_to_lua(lua_State *, nvpair_t *, char *, int);
 static int zcp_lua_to_nvlist_impl(lua_State *, int, nvlist_t *, const char *,
     int);
@@ -217,8 +222,6 @@ zcp_cleanup(lua_State *state)
 	}
 }
 
-#define	ZCP_NVLIST_MAX_DEPTH 20
-
 /*
  * Convert the lua table at the given index on the Lua stack to an nvlist
  * and return it.

module/zfs/zcp_global.c

@@ -14,7 +14,7 @@
  */
 
 /*
- * Copyright (c) 2016 by Delphix. All rights reserved.
+ * Copyright (c) 2016, 2017 by Delphix. All rights reserved.
  */
 
 #include <sys/zcp_global.h>
@@ -62,7 +62,12 @@ static const zcp_errno_global_t errno_globals[] = {
 	{"EPIPE", EPIPE},
 	{"EDOM", EDOM},
 	{"ERANGE", ERANGE},
+	{"EDEADLK", EDEADLK},
+	{"ENOLCK", ENOLCK},
+	{"ECANCELED", ECANCELED},
+	{"ENOTSUP", ENOTSUP},
 	{"EDQUOT", EDQUOT},
+	{"ENAMETOOLONG", ENAMETOOLONG},
 	{0, 0}
 };
 

module/zfs/zcp_synctask.c

@@ -39,10 +39,10 @@ typedef int (zcp_synctask_func_t)(lua_State *, boolean_t, nvlist_t *);
 typedef struct zcp_synctask_info {
 	const char *name;
 	zcp_synctask_func_t *func;
-	zfs_space_check_t space_check;
-	int blocks_modified;
 	const zcp_arg_t pargs[4];
 	const zcp_arg_t kwargs[2];
+	zfs_space_check_t space_check;
+	int blocks_modified;
 } zcp_synctask_info_t;
 
 /*
@@ -91,8 +91,6 @@ static int zcp_synctask_destroy(lua_State *, boolean_t, nvlist_t *);
 static zcp_synctask_info_t zcp_synctask_destroy_info = {
 	.name = "destroy",
 	.func = zcp_synctask_destroy,
-	.space_check = ZFS_SPACE_CHECK_NONE,
-	.blocks_modified = 0,
 	.pargs = {
 	    {.za_name = "filesystem | snapshot", .za_lua_type = LUA_TSTRING},
 	    {NULL, 0}
@@ -100,7 +98,9 @@ static zcp_synctask_info_t zcp_synctask_destroy_info = {
 	.kwargs = {
 	    {.za_name = "defer", .za_lua_type = LUA_TBOOLEAN},
 	    {NULL, 0}
-	}
+	},
+	.space_check = ZFS_SPACE_CHECK_NONE,
+	.blocks_modified = 0
 };
 
 /* ARGSUSED */
@@ -140,19 +140,19 @@ zcp_synctask_destroy(lua_State *state, boolean_t sync, nvlist_t *err_details)
 	return (err);
 }
 
-static int zcp_synctask_promote(lua_State *, boolean_t, nvlist_t *err_details);
+static int zcp_synctask_promote(lua_State *, boolean_t, nvlist_t *);
 static zcp_synctask_info_t zcp_synctask_promote_info = {
 	.name = "promote",
 	.func = zcp_synctask_promote,
-	.space_check = ZFS_SPACE_CHECK_RESERVED,
-	.blocks_modified = 3,
 	.pargs = {
 	    {.za_name = "clone", .za_lua_type = LUA_TSTRING},
 	    {NULL, 0}
 	},
 	.kwargs = {
 	    {NULL, 0}
-	}
+	},
+	.space_check = ZFS_SPACE_CHECK_RESERVED,
+	.blocks_modified = 3
 };
 
 static int
@@ -208,6 +208,58 @@ zcp_synctask_rollback(lua_State *state, boolean_t sync, nvlist_t *err_details)
 	return (err);
 }
 
+static int zcp_synctask_snapshot(lua_State *, boolean_t, nvlist_t *);
+static zcp_synctask_info_t zcp_synctask_snapshot_info = {
+	.name = "snapshot",
+	.func = zcp_synctask_snapshot,
+	.pargs = {
+	    {.za_name = "filesystem@snapname | volume@snapname",
+	    .za_lua_type = LUA_TSTRING},
+	    {NULL, 0}
+	},
+	.kwargs = {
+	    {NULL, 0}
+	},
+	.space_check = ZFS_SPACE_CHECK_NORMAL,
+	.blocks_modified = 3
+};
+
+/* ARGSUSED */
+static int
+zcp_synctask_snapshot(lua_State *state, boolean_t sync, nvlist_t *err_details)
+{
+	int err;
+	dsl_dataset_snapshot_arg_t ddsa = { 0 };
+	const char *dsname = lua_tostring(state, 1);
+	zcp_run_info_t *ri = zcp_run_info(state);
+
+	/*
+	 * We only allow for a single snapshot rather than a list, so the
+	 * error list output is unnecessary.
+	 */
+	ddsa.ddsa_errors = NULL;
+	ddsa.ddsa_props = NULL;
+	ddsa.ddsa_cr = ri->zri_cred;
+	ddsa.ddsa_snaps = fnvlist_alloc();
+	fnvlist_add_boolean(ddsa.ddsa_snaps, dsname);
+
+	/*
+	 * On old pools, the ZIL must not be active when a snapshot is created,
+	 * but we can't suspend the ZIL because we're already in syncing
+	 * context.
+	 */
+	if (spa_version(ri->zri_pool->dp_spa) < SPA_VERSION_FAST_SNAP) {
+		return (ENOTSUP);
+	}
+
+	err = zcp_sync_task(state, dsl_dataset_snapshot_check,
+	    dsl_dataset_snapshot_sync, &ddsa, sync, dsname);
+
+	fnvlist_free(ddsa.ddsa_snaps);
+
+	return (err);
+}
+
 void
 zcp_synctask_wrapper_cleanup(void *arg)
 {
@@ -279,6 +331,7 @@ zcp_load_synctask_lib(lua_State *state, boolean_t sync)
 		&zcp_synctask_destroy_info,
 		&zcp_synctask_promote_info,
 		&zcp_synctask_rollback_info,
+		&zcp_synctask_snapshot_info,
 		NULL
 	};
 

module/zfs/zfs_ioctl.c

@@ -3695,7 +3695,7 @@ zfs_ioc_channel_program(const char *poolname, nvlist_t *innvl,
 
 	if (instrlimit == 0 || instrlimit > zfs_lua_max_instrlimit)
 		return (EINVAL);
-	if (memlimit == 0 || memlimit > ZCP_MAX_MEMLIMIT)
+	if (memlimit == 0 || memlimit > zfs_lua_max_memlimit)
 		return (EINVAL);
 
 	return (zcp_eval(poolname, program, instrlimit, memlimit,

tests/runfiles/linux.run

@@ -67,8 +67,9 @@ tests = ['tst.args_to_lua', 'tst.divide_by_zero', 'tst.exists',
     'tst.integer_illegal', 'tst.integer_overflow', 'tst.language_functions_neg',
     'tst.language_functions_pos', 'tst.large_prog', 'tst.memory_limit',
     'tst.nested_neg', 'tst.nested_pos', 'tst.nvlist_to_lua',
-    'tst.recursive_neg', 'tst.recursive_pos', 'tst.return_nvlist_neg',
+    'tst.recursive_neg', 'tst.recursive_pos', 'tst.return_large',
-    'tst.return_nvlist_pos', 'tst.return_recursive_table', 'tst.timeout']
+    'tst.return_nvlist_neg', 'tst.return_nvlist_pos',
+    'tst.return_recursive_table', 'tst.timeout']
 tags = ['functional', 'channel_program', 'lua_core']
 
 [tests/functional/channel_program/synctask_core]
@@ -78,7 +79,9 @@ tests = ['tst.destroy_fs', 'tst.destroy_snap', 'tst.get_count_and_limit',
     'tst.get_userquota', 'tst.get_written', 'tst.list_children',
     'tst.list_clones', 'tst.list_snapshots', 'tst.list_system_props',
     'tst.parse_args_neg', 'tst.promote_conflict', 'tst.promote_multiple',
-    'tst.promote_simple', 'tst.rollback_mult', 'tst.rollback_one']
+    'tst.promote_simple', 'tst.rollback_mult', 'tst.rollback_one',
+    'tst.snapshot_destroy', 'tst.snapshot_neg', 'tst.snapshot_recursive',
+    'tst.snapshot_simple']
 tags = ['functional', 'channel_program', 'synctask_core']
 
 [tests/functional/chattr]

tests/zfs-tests/tests/functional/channel_program/lua_core/Makefile.am

@@ -26,6 +26,8 @@ dist_pkgdata_SCRIPTS = \
 	tst.recursive_neg.ksh \
 	tst.recursive_pos.ksh \
 	tst.recursive.zcp \
+	tst.return_large.ksh \
+	tst.return_large.zcp \
 	tst.return_nvlist_neg.ksh \
 	tst.return_nvlist_pos.ksh \
 	tst.return_recursive_table.ksh \

tests/zfs-tests/tests/functional/channel_program/lua_core/tst.return_large.ksh

@@ -0,0 +1,54 @@
+#!/bin/ksh -p
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/channel_program/channel_common.kshlib
+
+#
+# DESCRIPTION: Returning very large (up to the memory limit) lists should
+# function correctly.
+#
+
+verify_runnable "global"
+
+fs=$TESTPOOL/$TESTFS/testchild
+
+function cleanup
+{
+	datasetexists $fs && log_must zfs destroy -R $fs
+}
+
+log_onexit cleanup
+
+log_must zfs create $fs
+
+#
+# Actually checking in the ~500kb expected result of this program would be
+# awful, so we just make sure it was as long as we expected.
+#
+output_lines=$(log_must zfs program $TESTPOOL \
+    $ZCP_ROOT/lua_core/tst.return_large.zcp | wc -l)
+
+[[ $output_lines -lt 5000 ]] &&
+    log_fail "Expected return of full list but only got $output_lines lines"
+
+#
+# Make sure we fail if the return is over the memory limit
+#
+log_mustnot_program $TESTPOOL -m 10000 \
+    $ZCP_ROOT/lua_core/tst.return_large.zcp
+
+log_pass "Large return values work properly"
+

tests/zfs-tests/tests/functional/channel_program/lua_core/tst.return_large.zcp

@@ -0,0 +1,24 @@
+--
+-- This file and its contents are supplied under the terms of the
+-- Common Development and Distribution License ("CDDL"), version 1.0.
+-- You may only use this file in accordance with the terms of version
+-- 1.0 of the CDDL.
+--
+-- A full copy of the text of the CDDL should have accompanied this
+-- source.  A copy of the CDDL is also available via the Internet at
+-- http://www.illumos.org/license/CDDL.
+--
+
+--
+-- Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+--
+
+basestring = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" ..
+             "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
+
+ret = {}
+for i=1,5000 do
+    table.insert(ret, basestring)
+end
+
+return ret

tests/zfs-tests/tests/functional/channel_program/synctask_core/Makefile.am

@@ -29,4 +29,12 @@ dist_pkgdata_SCRIPTS = \
 	tst.promote_multiple.ksh \
 	tst.promote_simple.ksh \
 	tst.rollback_mult.ksh \
-	tst.rollback_one.ksh
+	tst.rollback_one.ksh \
+	tst.snapshot_destroy.ksh \
+	tst.snapshot_destroy.zcp \
+	tst.snapshot_neg.ksh \
+	tst.snapshot_neg.zcp \
+	tst.snapshot_recursive.ksh \
+	tst.snapshot_recursive.zcp \
+	tst.snapshot_simple.ksh \
+	tst.snapshot_simple.zcp

tests/zfs-tests/tests/functional/channel_program/synctask_core/tst.snapshot_destroy.ksh

@@ -0,0 +1,39 @@
+#!/bin/ksh -p
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/channel_program/channel_common.kshlib
+
+#
+# DESCRIPTION: Creating and destroying snapshots in the same txg should work.
+#
+
+verify_runnable "global"
+
+fs=$TESTPOOL/$TESTFS/testchild
+
+function cleanup
+{
+	datasetexists $fs && log_must zfs destroy -R $fs
+}
+
+log_onexit cleanup
+
+log_must zfs create $fs
+
+log_must_program $TESTPOOL \
+    $ZCP_ROOT/synctask_core/tst.snapshot_destroy.zcp $fs
+
+log_pass "Creating/destroying snapshots in one channel program works"

tests/zfs-tests/tests/functional/channel_program/synctask_core/tst.snapshot_destroy.zcp

@@ -0,0 +1,24 @@
+--
+-- This file and its contents are supplied under the terms of the
+-- Common Development and Distribution License ("CDDL"), version 1.0.
+-- You may only use this file in accordance with the terms of version
+-- 1.0 of the CDDL.
+--
+-- A full copy of the text of the CDDL should have accompanied this
+-- source.  A copy of the CDDL is also available via the Internet at
+-- http://www.illumos.org/license/CDDL.
+--
+
+--
+-- Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+--
+
+args = ...
+argv = args["argv"]
+
+assert(zfs.sync.snapshot(argv[1] .. "@snap1") == 0)
+assert(zfs.sync.destroy(argv[1] .. "@snap1") == 0)
+
+for s in zfs.list.snapshots(argv[1]) do
+	assert(false)
+end

tests/zfs-tests/tests/functional/channel_program/synctask_core/tst.snapshot_neg.ksh

@@ -0,0 +1,44 @@
+#!/bin/ksh -p
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/channel_program/channel_common.kshlib
+
+#
+# DESCRIPTION: Check various invalid snapshot error cases
+#
+
+verify_runnable "global"
+
+fs1=$TESTPOOL/$TESTFS/testchild1
+fs2=$TESTPOOL/$TESTFS/testchild2
+
+function cleanup
+{
+	for fs in $fs1 $fs2; do
+		datasetexists $fs && log_must zfs destroy -R $fs
+	done
+}
+
+log_onexit cleanup
+
+log_must zfs create $fs1
+log_must zfs create $fs2
+log_must zfs snapshot $fs1@snap1
+
+log_must_program $TESTPOOL $ZCP_ROOT/synctask_core/tst.snapshot_neg.zcp $fs1 $fs2
+
+log_pass "zfs.sync.snapshot returns correct errors on invalid input"
+

tests/zfs-tests/tests/functional/channel_program/synctask_core/tst.snapshot_neg.zcp

@@ -0,0 +1,35 @@
+--
+-- This file and its contents are supplied under the terms of the
+-- Common Development and Distribution License ("CDDL"), version 1.0.
+-- You may only use this file in accordance with the terms of version
+-- 1.0 of the CDDL.
+--
+-- A full copy of the text of the CDDL should have accompanied this
+-- source.  A copy of the CDDL is also available via the Internet at
+-- http://www.illumos.org/license/CDDL.
+--
+
+--
+-- Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+--
+
+args = ...
+argv = args["argv"]
+fs1 = argv[1]
+fs2 = argv[2]
+
+longstring = "a"
+for i=1,9 do
+    longstring = longstring .. longstring
+end
+
+-- invalid snapshot names
+assert(zfs.sync.snapshot("ceci_nest_pas_une_dataset") == EINVAL);
+assert(zfs.sync.snapshot(fs1) == EINVAL)
+assert(zfs.sync.snapshot(fs1 .. "@" .. longstring) == ENAMETOOLONG)
+
+assert(zfs.sync.snapshot(fs2 .. "@snap1") == 0)
+-- only one snapshot of a filesystem is allowed per TXG.
+assert(zfs.sync.snapshot(fs2 .. "@snap2") == EAGAIN)
+-- snapshot already exists
+assert(zfs.sync.snapshot(fs1 .. "@snap1") == EEXIST)

tests/zfs-tests/tests/functional/channel_program/synctask_core/tst.snapshot_recursive.ksh

@@ -0,0 +1,61 @@
+#!/bin/ksh -p
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/channel_program/channel_common.kshlib
+
+#
+# DESCRIPTION: Construct a set of nested filesystems, then recursively snapshot
+# all of them.
+#
+
+verify_runnable "global"
+
+rootfs=$TESTPOOL/$TESTFS/root
+snapname=snap
+
+function cleanup
+{
+	datasetexists $rootfs && log_must zfs destroy -R $rootfs
+}
+
+log_onexit cleanup
+
+filesystems="$rootfs \
+$rootfs/child1 \
+$rootfs/child1/subchild1 \
+$rootfs/child1/subchild2 \
+$rootfs/child1/subchild3 \
+$rootfs/child2 \
+$rootfs/child2/subchild4 \
+$rootfs/child2/subchild5"
+
+for fs in $filesystems; do
+    log_must zfs create $fs
+done
+
+log_must_program $TESTPOOL \
+    $ZCP_ROOT/synctask_core/tst.snapshot_recursive.zcp $rootfs $snapname
+
+#
+# Make sure all of the snapshots we expect were created.
+#
+for fs in $filesystems; do
+    log_must snapexists $fs@$snapname
+done
+
+log_pass "Recursively snapshotting multiple filesystems works."
+
+

tests/zfs-tests/tests/functional/channel_program/synctask_core/tst.snapshot_recursive.zcp

@@ -0,0 +1,28 @@
+--
+-- This file and its contents are supplied under the terms of the
+-- Common Development and Distribution License ("CDDL"), version 1.0.
+-- You may only use this file in accordance with the terms of version
+-- 1.0 of the CDDL.
+--
+-- A full copy of the text of the CDDL should have accompanied this
+-- source.  A copy of the CDDL is also available via the Internet at
+-- http://www.illumos.org/license/CDDL.
+--
+
+--
+-- Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+--
+
+args = ...
+argv = args["argv"]
+fs = argv[1]
+snap = argv[2]
+
+function snapshot_recursive(root)
+    assert(zfs.sync.snapshot(root .. "@" .. snap) == 0)
+    for child in zfs.list.children(root) do
+        snapshot_recursive(child)
+    end
+end
+
+snapshot_recursive(fs)

tests/zfs-tests/tests/functional/channel_program/synctask_core/tst.snapshot_simple.ksh

@@ -0,0 +1,40 @@
+#!/bin/ksh -p
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+
+#
+# Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/channel_program/channel_common.kshlib
+
+#
+# DESCRIPTION: Make sure basic snapshot functionality works in channel programs
+#
+
+verify_runnable "global"
+
+fs=$TESTPOOL/$TESTFS/testchild
+snapname=testsnap
+
+function cleanup
+{
+	datasetexists $fs && log_must zfs destroy -R $fs
+}
+
+log_onexit cleanup
+
+log_must zfs create $fs
+
+log_must_program $TESTPOOL \
+    $ZCP_ROOT/synctask_core/tst.snapshot_simple.zcp $fs $snapname
+
+log_pass "Simple snapshotting works"

tests/zfs-tests/tests/functional/channel_program/synctask_core/tst.snapshot_simple.zcp

@@ -0,0 +1,26 @@
+--
+-- This file and its contents are supplied under the terms of the
+-- Common Development and Distribution License ("CDDL"), version 1.0.
+-- You may only use this file in accordance with the terms of version
+-- 1.0 of the CDDL.
+--
+-- A full copy of the text of the CDDL should have accompanied this
+-- source.  A copy of the CDDL is also available via the Internet at
+-- http://www.illumos.org/license/CDDL.
+--
+
+--
+-- Copyright (c) 2016, 2017 by Delphix. All rights reserved.
+--
+
+-- This program should be invoked as "zfs program <pool> <prog> <fs> <snap>"
+
+args = ...
+argv = args["argv"]
+assert(zfs.sync.snapshot(argv[1] .. "@" .. argv[2]) == 0)
+snaps = {}
+for s in zfs.list.snapshots(argv[1]) do
+	table.insert(snaps, s)
+end
+assert(#snaps == 1)
+assert(snaps[1] == (argv[1] .. "@" .. argv[2]))