zhack: Add repair label option

In case if all label checksums will be invalid on any vdev, the pool
will become unimportable. The zhack with newly added cli options could
be used to restore label checksums and make pool importable again.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Fedor Uporov <fuporov.vstack@gmail.com>
Closes #2510
Closes #12686

tests/runfiles/common.run

@@ -317,6 +317,12 @@ tags = ['functional', 'cli_root', 'zfs_upgrade']
 tests = ['zfs_wait_deleteq']
 tags = ['functional', 'cli_root', 'zfs_wait']
 
+[tests/functional/cli_root/zhack]
+tests = ['zhack_label_checksum']
+pre =
+post =
+tags = ['functional', 'cli_root', 'zhack']
+
 [tests/functional/cli_root/zpool]
 tests = ['zpool_001_neg', 'zpool_002_pos', 'zpool_003_pos', 'zpool_colors']
 tags = ['functional', 'cli_root', 'zpool']

tests/zfs-tests/tests/functional/cli_root/Makefile.am

@@ -35,6 +35,7 @@ SUBDIRS = \
 	zfs_unshare \
 	zfs_upgrade \
 	zfs_wait \
+	zhack \
 	zpool \
 	zpool_add \
 	zpool_attach \

tests/zfs-tests/tests/functional/cli_root/zhack/Makefile.am

@@ -0,0 +1,3 @@
+pkgdatadir = $(datadir)/@PACKAGE@/zfs-tests/tests/functional/cli_root/zhack
+dist_pkgdata_SCRIPTS = \
+	zhack_label_checksum.ksh

tests/zfs-tests/tests/functional/cli_root/zhack/zhack_label_checksum.ksh

@@ -0,0 +1,64 @@
+#!/bin/ksh
+
+#
+# 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) 2021 by vStack. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/include/blkdev.shlib
+
+#
+# Description:
+# zhack label repair <vdev> will calculate and rewrite label checksum if invalid
+#
+# Strategy:
+# 1. Create pool with some number of vdevs and export it
+# 2. Corrupt all labels checksums
+# 3. Check that pool cannot be imported
+# 4. Use zhack to repair labels checksums
+# 5. Check that pool can be imported
+#
+
+log_assert "Verify zhack label repair <vdev> will repair labels checksums"
+log_onexit cleanup
+
+VIRTUAL_DISK=$TEST_BASE_DIR/disk
+
+function cleanup
+{
+	poolexists $TESTPOOL && destroy_pool $TESTPOOL
+	[[ -f $VIRTUAL_DISK ]] && log_must rm $VIRTUAL_DISK
+}
+
+log_must truncate -s $(($MINVDEVSIZE * 8)) $VIRTUAL_DISK
+
+log_must zpool create $TESTPOOL $VIRTUAL_DISK
+log_must zpool export $TESTPOOL
+
+log_mustnot zhack label repair $VIRTUAL_DISK
+
+corrupt_label_checksum 0 $VIRTUAL_DISK
+corrupt_label_checksum 1 $VIRTUAL_DISK
+corrupt_label_checksum 2 $VIRTUAL_DISK
+corrupt_label_checksum 3 $VIRTUAL_DISK
+
+log_mustnot zpool import $TESTPOOL -d $TEST_BASE_DIR
+
+log_must zhack label repair $VIRTUAL_DISK
+
+log_must zpool import $TESTPOOL -d $TEST_BASE_DIR
+
+cleanup
+
+log_pass "zhack label repair works correctly."