[PATCH v3 storage 17/76] diskmanage: link multipath member disks to their map device

[Thomas Lamprecht <t.lamprecht@proxmox.com>]

From: Dietmar Maurer <dietmar@proxmox.com>

The generic 'Device Mapper' usage neither identifies a multipath map
nor links its member paths. Report the map's device path in the
multipath property so clients can group members or hide them in favor
of the map.

Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
[TL: drop redundant comments; clarify the multipath member description]
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
 src/PVE/API2/Disks.pm                         |  7 +++++
 src/PVE/Diskmanage.pm                         | 31 +++++++++++++++++++
 .../multipath/disklist_expected.json          | 12 ++++---
 3 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/src/PVE/API2/Disks.pm b/src/PVE/API2/Disks.pm
index fe383319..dd3524b5 100644
--- a/src/PVE/API2/Disks.pm
+++ b/src/PVE/API2/Disks.pm
@@ -150,6 +150,13 @@ __PACKAGE__->register_method({
                         . " 'iscsi', 'nvme', 'nvme-fc', or 'nvme-tcp'.",
                     optional => 1,
                 },
+                multipath => {
+                    type => 'string',
+                    description =>
+                        'The device path of the multipath map this device belongs to.'
+                        . ' Only set for multipath member devices.',
+                    optional => 1,
+                },
                 parent => {
                     type => 'string',
                     description => 'For partitions only. The device path of '
diff --git a/src/PVE/Diskmanage.pm b/src/PVE/Diskmanage.pm
index be7d9828..807ef0ca 100644
--- a/src/PVE/Diskmanage.pm
+++ b/src/PVE/Diskmanage.pm
@@ -574,12 +574,40 @@ sub mounted_paths {
     return $mounted;
 }
 
+my sub get_multipath_slave_map {
+    my $slave_map = {};
+
+    dir_glob_foreach(
+        '/sys/block',
+        'dm-\d+',
+        sub {
+            my ($dev) = @_;
+            my $sysdir = "/sys/block/$dev";
+
+            my $uuid = file_read_firstline("$sysdir/dm/uuid") // return;
+            return if $uuid !~ m/^mpath-/;
+
+            my $name = file_read_firstline("$sysdir/dm/name") // return;
+
+            dir_glob_foreach(
+                "$sysdir/slaves",
+                '[^.].*',
+                sub { $slave_map->{ $_[0] } = "/dev/mapper/$name"; },
+            );
+        },
+    );
+
+    return $slave_map;
+}
+
 sub get_disks {
     my ($disks, $nosmart, $include_partitions) = @_;
     my $disklist = {};
 
     my $mounted = mounted_blockdevs();
 
+    my $mpath_slave_map = get_multipath_slave_map();
+
     my $lsblk_info = get_lsblk_info();
 
     my $journalhash = get_ceph_journals($lsblk_info);
@@ -697,6 +725,9 @@ sub get_disks {
             $disklist->{$dev}->{transport} = $transport if defined($transport);
             $disklist->{$dev}->{mounted} = 1 if exists $mounted->{$devpath};
 
+            my $mpath = $mpath_slave_map->{$dev};
+            $disklist->{$dev}->{multipath} = $mpath if defined($mpath);
+
             my $by_id_link = $data->{by_id_link};
             $disklist->{$dev}->{by_id_link} = $by_id_link if defined($by_id_link);
 
diff --git a/src/test/disk_tests/multipath/disklist_expected.json b/src/test/disk_tests/multipath/disklist_expected.json
index ec442969..001193da 100644
--- a/src/test/disk_tests/multipath/disklist_expected.json
+++ b/src/test/disk_tests/multipath/disklist_expected.json
@@ -15,7 +15,8 @@
         "osdid-list": null,
         "by_id_link": "/dev/disk/by-id/scsi-36001405000000000000000000000000a",
         "transport": "fc",
-        "used": "Device Mapper"
+        "used": "Device Mapper",
+        "multipath": "/dev/mapper/mpatha"
     },
     "sdb": {
         "devpath": "/dev/sdb",
@@ -33,7 +34,8 @@
         "osdid-list": null,
         "by_id_link": "/dev/disk/by-id/scsi-36001405000000000000000000000000b",
         "transport": "fc",
-        "used": "Device Mapper"
+        "used": "Device Mapper",
+        "multipath": "/dev/mapper/mpatha"
     },
     "sdc": {
         "devpath": "/dev/sdc",
@@ -51,7 +53,8 @@
         "osdid-list": null,
         "by_id_link": "/dev/disk/by-id/scsi-36001405000000000000000000000000c",
         "transport": "fc",
-        "used": "Device Mapper"
+        "used": "Device Mapper",
+        "multipath": "/dev/mapper/mpathb"
     },
     "sdd": {
         "devpath": "/dev/sdd",
@@ -69,7 +72,8 @@
         "osdid-list": null,
         "by_id_link": "/dev/disk/by-id/scsi-36001405000000000000000000000000d",
         "transport": "fc",
-        "used": "Device Mapper"
+        "used": "Device Mapper",
+        "multipath": "/dev/mapper/mpathb"
     },
     "nvme8n1": {
         "devpath": "/dev/nvme8n1",
-- 
2.47.3