Test cancelling a removal in ZTS

This patch adds a new test that sanity checks cancelling a removal.

Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Closes #9101

tests/runfiles/linux.run

@@ -769,7 +769,7 @@ tags = ['functional', 'refreserv']
 
 [tests/functional/removal]
 pre =
-tests = ['removal_all_vdev', 'removal_check_space',
+tests = ['removal_all_vdev', 'removal_cancel', 'removal_check_space',
     'removal_condense_export', 'removal_multiple_indirection',
     'removal_nopwrite', 'removal_remap_deadlists',
     'removal_resume_export', 'removal_sanity', 'removal_with_add',

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

@@ -10,14 +10,15 @@
 #
 
 #
-# Copyright (c) 2014, 2015 by Delphix. All rights reserved.
+# Copyright (c) 2014, 2019 by Delphix. All rights reserved.
 #
 
 pkgdatadir = $(datadir)/@PACKAGE@/zfs-tests/tests/functional/removal
 
 dist_pkgdata_SCRIPTS = \
-	cleanup.ksh removal_all_vdev.ksh removal_check_space.ksh \
+	cleanup.ksh removal_all_vdev.ksh removal_cancel.ksh \
-	removal_condense_export.ksh removal_multiple_indirection.ksh \
+	removal_check_space.ksh removal_condense_export.ksh \
+	removal_multiple_indirection.ksh \
 	removal_nopwrite.ksh removal_remap_deadlists.ksh \
 	removal_reservation.ksh removal_resume_export.ksh \
 	removal_sanity.ksh removal_with_add.ksh removal_with_create_fs.ksh \

tests/zfs-tests/tests/functional/removal/removal_cancel.ksh

@@ -0,0 +1,99 @@
+#! /bin/ksh -p
+#
+# CDDL HEADER START
+#
+# 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.
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2018 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/functional/removal/removal.kshlib
+
+#
+# DESCRIPTION:
+#
+# Ensure that cancelling a removal midway does not cause any
+# issues like cause a panic.
+#
+# STRATEGY:
+#
+# 1. Create a pool with one vdev and do some writes on it.
+# 2. Add a new vdev to the pool and start the removal of
+#    the first vdev.
+# 3. Cancel the removal after some segments have been copied
+#    over to the new vdev.
+# 4. Run zdb to ensure the on-disk state of the pool is ok.
+#
+
+function cleanup
+{
+	#
+	# Reset tunable.
+	#
+	log_must set_tunable32 zfs_removal_suspend_progress 0
+}
+log_onexit cleanup
+
+SAMPLEFILE=/$TESTDIR/00
+
+#
+# Create pool with one disk.
+#
+log_must default_setup_noexit "$REMOVEDISK"
+
+#
+# Create a file of size 1GB and then do some random writes.
+# Since randwritecomp does 8K writes we do 12500 writes
+# which means we write ~100MB to the vdev.
+#
+log_must mkfile -n 1g $SAMPLEFILE
+log_must randwritecomp $SAMPLEFILE 12500
+
+#
+# Add second device where all the data will be evacuated.
+#
+log_must zpool add -f $TESTPOOL $NOTREMOVEDISK
+
+#
+# Start removal.
+#
+log_must zpool remove $TESTPOOL $REMOVEDISK
+
+#
+# Sleep a bit and hopefully allow removal to copy some data.
+#
+log_must sleep 1
+
+#
+# Block removal.
+#
+log_must set_tunable32 zfs_removal_suspend_progress 1
+
+#
+# Only for debugging purposes in test logs.
+#
+log_must zpool status $TESTPOOL
+
+#
+# Cancel removal.
+#
+log_must zpool remove -s $TESTPOOL
+
+#
+# Verify on-disk state.
+#
+log_must zdb $TESTPOOL
+
+log_pass "Device removal thread cancelled successfully."