ZTS: test that zdb can work with libzpool tunables

Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes #17537

tests/runfiles/common.run

@@ -170,7 +170,8 @@ tests = ['zdb_002_pos', 'zdb_003_pos', 'zdb_004_pos', 'zdb_005_pos',
     'zdb_block_size_histogram', 'zdb_checksum', 'zdb_decompress',
     'zdb_display_block', 'zdb_encrypted', 'zdb_label_checksum',
     'zdb_object_range_neg', 'zdb_object_range_pos', 'zdb_objset_id',
-    'zdb_decompress_zstd', 'zdb_recover', 'zdb_recover_2', 'zdb_backup']
+    'zdb_decompress_zstd', 'zdb_recover', 'zdb_recover_2', 'zdb_backup',
+    'zdb_tunables']
 pre =
 post =
 tags = ['functional', 'cli_root', 'zdb']

tests/zfs-tests/tests/Makefile.am

@@ -645,6 +645,7 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
 	functional/cli_root/zdb/zdb_objset_id.ksh \
 	functional/cli_root/zdb/zdb_recover_2.ksh \
 	functional/cli_root/zdb/zdb_recover.ksh \
+	functional/cli_root/zdb/zdb_tunables.ksh \
 	functional/cli_root/zfs_bookmark/cleanup.ksh \
 	functional/cli_root/zfs_bookmark/setup.ksh \
 	functional/cli_root/zfs_bookmark/zfs_bookmark_cliargs.ksh \

tests/zfs-tests/tests/functional/cli_root/zdb/zdb_tunables.ksh

@@ -0,0 +1,71 @@
+#!/bin/ksh -p
+# SPDX-License-Identifier: CDDL-1.0
+#
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2025, Rob Norris <robn@despairlabs.com>
+#
+
+. $STF_SUITE/include/libtest.shlib
+
+verify_runnable "both"
+
+log_assert "zdb can work with libzpool tunables"
+
+# a tunable name by itself, or with the "show" command, produces name and value
+log_must eval 'zdb -o zfs_recover | grep -qE "^zfs_recover: 0$"'
+log_must eval 'zdb -o show=zfs_recover | grep -qE "^zfs_recover: 0$"'
+
+# info about a tunable shows a different format
+log_must eval 'zdb -o info=zfs_recover | grep -qE "^zfs_recover \[[[:alnum:]_]+ r[dw]]: .+"'
+
+# "show" by itself shows all the tunables and their values
+# this tests limits to 50 tunables, and then counts the number that match
+# the format, which should be all of them
+log_must test $(zdb -o show | head -50 | grep -cE "^[[:alnum:]_]+: .+") -eq 50
+
+# "info" by itself shows info about all tunables
+# like previous test, we limit and then count
+log_must test $(zdb -o info | head -50 | grep -cE "^[[:alnum:]_]+ \[[[:alnum:]_]+ r[dw]]: .+") -eq 50
+
+# can't lookup nonexistent tunables
+log_mustnot_expect 'no such tunable: hello' zdb -o hello
+log_mustnot_expect 'no such tunable: hello' zdb -o show=hello
+log_mustnot_expect 'no such tunable: hello' zdb -o info=hello
+
+# setting a tunable shows the old and the new value
+log_must eval 'zdb -o zfs_recover=1 | grep -qE "^zfs_recover: 0 -> 1$"'
+
+# replacing a value still sets it
+log_must eval 'zdb -o zfs_recover=0 | grep -qE "^zfs_recover: 0 -> 0$"'
+
+# can't set the "magic" commands
+log_mustnot_expect 'no such tunable: 0' zdb -o show=0
+log_mustnot_expect 'no such tunable: 1' zdb -o info=1
+
+# can set multiple in same command
+log_must eval 'zdb -o zfs_recover=1 -o zfs_flags=512 | xargs | grep -qE "^zfs_recover: 0 -> 1 zfs_flags: 4294965758 -> 512$"'
+
+# can set and show in same command
+log_must eval 'zdb -o zfs_recover=1 -o zfs_recover -o zfs_recover=0 | xargs | grep -qE "^zfs_recover: 0 -> 1 zfs_recover: 1 zfs_recover: 1 -> 0$"'
+
+log_pass "zdb can work with libzpool tunables"