OpenZFS 9591 - ms_shift can be incorrectly changed

ms_shift can be incorrectly changed changed in MOS config for
indirect vdevs that have been historically expanded

According to spa_config_update() we expect new vdevs to have
vdev_ms_array equal to 0 and then we go ahead and set their metaslab
size. The problem is that indirect vdevs also have vdev_ms_array == 0
because their metaslabs are destroyed once their removal is done.

As a result, if a vdev was expanded and then removed may have its
ms_shift changed if another vdev was added after its removal.
Fortunately this behavior does not cause any type of crash or bad
behavior in the kernel but it can confuse zdb and anyone doing any kind
of analysis of the history of the pools.

Authored by: Serapheim Dimitropoulos <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>
Reviewed by: George Wilson <[email protected]>
Reviewed by: John Kennedy <[email protected]>
Reviewed by: Prashanth Sreenivasa <[email protected]>
Reviewed by: Brian Behlendorf <[email protected]>
Signed-off-by: Tim Chase <[email protected]>
Ported-by: Tim Chase <[email protected]>

OpenZFS-commit: https://github.com/openzfs/openzfs/pull/651
OpenZFS-issue: https://illumos.org/issues/9591a
External-issue: DLPX-58879
Closes #7644

2 files changed, 90 insertions, 1 deletions

diff --git a/tests/zfs-tests/tests/functional/removal/Makefile.am b/tests/zfs-tests/tests/functional/removal/Makefile.am
index eac82a2f1..c2b333a00 100644
--- a/tests/zfs-tests/tests/functional/removal/Makefile.am
+++ b/tests/zfs-tests/tests/functional/removal/Makefile.am
@@ -27,6 +27,6 @@ dist_pkgdata_SCRIPTS = \
 	removal_with_send.ksh removal_with_send_recv.ksh \
 	removal_with_snapshot.ksh removal_with_write.ksh \
 	removal_with_zdb.ksh remove_mirror.ksh remove_mirror_sanity.ksh \
-	remove_raidz.ksh removal.kshlib
+	remove_raidz.ksh remove_expanded.ksh removal.kshlib
 
 pkgexecdir = $(datadir)/@PACKAGE@/zfs-tests/tests/functional/removal
diff --git a/tests/zfs-tests/tests/functional/removal/remove_expanded.ksh b/tests/zfs-tests/tests/functional/removal/remove_expanded.ksh
new file mode 100755
index 000000000..e7e63b705
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/removal/remove_expanded.ksh
@@ -0,0 +1,89 @@
+#! /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
+. $STF_SUITE/tests/functional/removal/removal.kshlib
+
+#
+# BACKGROUND:
+#
+# ztest hit an issue where it ran zdb and zdb failed because
+# it couldn't access some indirect mappings at the end of a
+# vdev. The issue was that the vdev's ms_shift had changed after
+# it was removed by the addition of another vdev. This test is
+# a regression test for ensuring this case doesn't come up again.
+#
+
+
+TMPDIR=${TMPDIR:-$TEST_BASE_DIR}
+DISK0=$TMPDIR/dsk0
+DISK1=$TMPDIR/dsk1
+DISK2=$TMPDIR/dsk2
+
+log_must truncate -s $MINVDEVSIZE $DISK0
+log_must truncate -s $(($MINVDEVSIZE * 3)) $DISK1
+log_must truncate -s $MINVDEVSIZE $DISK2
+
+function cleanup
+{
+	default_cleanup_noexit
+	log_must rm -f $DISK0 $DISK1 $DISK2
+}
+
+#
+# Setup the pool with one disk .
+#
+log_must default_setup_noexit "$DISK0"
+log_onexit cleanup
+
+#
+# Expand vdev.
+#
+log_must truncate -s $(($MINVDEVSIZE * 2)) $DISK0
+log_must zpool reopen $TESTPOOL
+log_must zpool online -e $TESTPOOL $DISK0
+
+#
+# Fill up the whole vdev.
+#
+dd if=/dev/urandom of=$TESTDIR/$TESTFILE0 bs=8M
+
+#
+# Add another vdev and remove the first vdev creating indirect
+# mappings for nearly all the allocatable space from the first
+# vdev. Wait for removal to finish.
+#
+log_must zpool add $TESTPOOL $DISK1
+log_must zpool remove $TESTPOOL $DISK0
+log_must wait_for_removal $TESTPOOL
+
+#
+# Add a new vdev that will trigger a change in the config.
+# Run sync once to ensure that the config actually changed.
+#
+log_must zpool add $TESTPOOL $DISK2
+log_must sync
+
+#
+# Ensure that zdb does not find any problems with this.
+#
+log_must zdb $TESTPOOL
+
+log_pass "Removal of expanded vdev doesn't cause any problems."