File: 0012-lvchange-reject-writemostly-writebehind-on-raid1-dur.patch

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From 27e1059ec6e67a4ac0faaf0f53cd086ac4ed0e35 Mon Sep 17 00:00:00 2001
From: Heinz Mauelshagen <heinzm@redhat.com>
Date: Thu, 23 Feb 2017 15:09:29 +0100
Subject: lvchange: reject writemostly/writebehind on raid1 during resync

The MD kernel raid1 personality does no use any writemostly leg as the primary.

In case a previous linear LV holding data gets upconverted to
raid1 it becomes the primary leg of the new raid1 LV and a full
resynchronization is started to update the new legs.

No writemostly and/or writebehind setting may be allowed during
this initial, full synchronization period of this new raid1 LV
(using the lvchange(8) command), because that would change the
primary (i.e the previous linear LV) thus causing data loss.

lvchange has a bug not preventing this scenario.

Fix rejects setting writemostly and/or writebehind on resychronizing raid1 LVs.

Once we have status in the lvm2 metadata about the linear -> raid upconversion,
we may relax this constraint for other types of resynchronization
(e.g. for user requested "lvchange --resync ").

New lvchange-raid1-writemostly.sh test is added to the test suite.

Resolves: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=855895
---
 lib/metadata/metadata-exported.h         |  1 +
 lib/metadata/raid_manip.c                |  8 ++++++-
 test/shell/lvchange-raid1-writemostly.sh | 41 ++++++++++++++++++++++++++++++++
 tools/lvchange.c                         | 15 ++++++++++++
 4 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 test/shell/lvchange-raid1-writemostly.sh

diff --git a/lib/metadata/metadata-exported.h b/lib/metadata/metadata-exported.h
index cdd4984c1..080073925 100644
--- a/lib/metadata/metadata-exported.h
+++ b/lib/metadata/metadata-exported.h
@@ -1212,6 +1212,7 @@ int lv_raid_replace(struct logical_volume *lv, int force,
 		    struct dm_list *remove_pvs, struct dm_list *allocate_pvs);
 int lv_raid_remove_missing(struct logical_volume *lv);
 int partial_raid_lv_supports_degraded_activation(const struct logical_volume *lv);
+int lv_raid_in_sync(const struct logical_volume *lv);
 /* --  metadata/raid_manip.c */
 
 /* ++  metadata/cache_manip.c */
diff --git a/lib/metadata/raid_manip.c b/lib/metadata/raid_manip.c
index 7e591e988..00e5551a3 100644
--- a/lib/metadata/raid_manip.c
+++ b/lib/metadata/raid_manip.c
@@ -268,7 +268,7 @@ static int _deactivate_and_remove_lvs(struct volume_group *vg, struct dm_list *r
  * Returns: 1 if in-sync, 0 otherwise.
  */
 #define _RAID_IN_SYNC_RETRIES  6
-static int _raid_in_sync(struct logical_volume *lv)
+static int _raid_in_sync(const struct logical_volume *lv)
 {
 	int retries = _RAID_IN_SYNC_RETRIES;
 	dm_percent_t sync_percent;
@@ -299,6 +299,12 @@ static int _raid_in_sync(struct logical_volume *lv)
 	return (sync_percent == DM_PERCENT_100) ? 1 : 0;
 }
 
+/* External interface to raid in-sync check */
+int lv_raid_in_sync(const struct logical_volume *lv)
+{
+	return _raid_in_sync(lv);
+}
+
 /* Check if RaidLV @lv is synced or any raid legs of @lv are not synced */
 static int _raid_devs_sync_healthy(struct logical_volume *lv)
 {
diff --git a/test/shell/lvchange-raid1-writemostly.sh b/test/shell/lvchange-raid1-writemostly.sh
new file mode 100644
index 000000000..edf11bd4e
--- /dev/null
+++ b/test/shell/lvchange-raid1-writemostly.sh
@@ -0,0 +1,41 @@
+#!/bin/sh
+# Copyright (C) 2017 Red Hat, Inc. All rights reserved.
+#
+# This copyrighted material is made available to anyone wishing to use,
+# modify, copy, or redistribute it subject to the terms and conditions
+# of the GNU General Public License v.2.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA2110-1301 USA
+
+SKIP_WITH_LVMLOCKD=1
+SKIP_WITH_LVMPOLLD=1
+
+. lib/inittest
+
+which mkfs.ext4 || skip
+aux have_raid 1 3 5 || skip
+
+aux prepare_vg 4
+
+for d in $dev1 $dev2 $dev3 $dev4
+do
+	aux delay_dev $d 1
+done
+
+#
+# Test writemostly prohibited on resyncrhonizing raid1
+#
+
+# Create 4-way striped LV
+lvcreate -aey --ty raid1 -m 3 -L 32M -n $lv1 $vg
+not lvchange -y --writemostly $dev1 $vg/$lv1
+check lv_field $vg/$lv1 segtype "raid1"
+check lv_field $vg/$lv1 stripes 4
+check lv_attr_bit health $vg/${lv1}_rimage_0 "-"
+aux wait_for_sync $vg $lv1
+lvchange -y --writemostly $dev1 $vg/$lv1
+check lv_attr_bit health $vg/${lv1}_rimage_0 "w"
+
+vgremove -ff $vg
diff --git a/tools/lvchange.c b/tools/lvchange.c
index 250d7209b..964eb5179 100644
--- a/tools/lvchange.c
+++ b/tools/lvchange.c
@@ -821,6 +821,21 @@ static int _lvchange_writemostly(struct logical_volume *lv)
 		return 0;
 	}
 
+	/*
+	 * Prohibit writebehind and writebehind during synchronization.
+	 *
+	 * FIXME: we can do better once we can distingush between
+	 *        an initial sync after a linear -> raid1 upconversion
+	 *        and any later additions of legs, requested resyncs
+	 *        via lvchange or leg repairs/replacements.
+	 */
+	if (!lv_raid_in_sync(lv)) {
+		log_error("Unable to change write%s on %s while it is not in-sync.",
+			  arg_is_set(cmd, writemostly_ARG) ? "mostly" : "behind",
+			  display_lvname(lv));
+		return 0;
+	}
+
 	if (arg_is_set(cmd, writebehind_ARG))
 		raid_seg->writebehind = arg_uint_value(cmd, writebehind_ARG, 0);