[PATCH qemu-server v5 1/4] hotplug: scsi: only keep controller if a disk on it is still present

[Dominik Csapak <d.csapak@proxmox.com>]

The check whether a non-single SCSI controller is still in use compared
the disk index against (maxdev - 1) * (controller + 1). For LSI (7 disks
per controller), this ignores the last slot of the first controller for
example, and treats any disk on a lower controller as user of the higher
ones.

So unplugging scsi0 with only scsi6 left unplugged the controller
that scsi6 is still attached to, while unplugging scsi7 left the then
unused second controller behind.

Use scsihw_infos() to determine the controller of each remaining
disk, like when plugging them, and only keep the controller if one of
them is on it.

Also don't rely on the drive being in the config, since on hotplug
cleanup this does not have to be the case. This combines the index
extraction with the check for 'scsi'.

The added regression tests would have failed without the code change.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
 src/PVE/QemuServer.pm                            | 13 ++++---------
 src/test/hotplug/disk-remove-lsi-last-slot.conf  | 16 ++++++++++++++++
 .../disk-remove-lsi-last-slot.conf.expected      |  3 +++
 .../disk-remove-lsi-second-controller.conf       | 16 ++++++++++++++++
 ...sk-remove-lsi-second-controller.conf.expected |  4 ++++
 5 files changed, 43 insertions(+), 9 deletions(-)
 create mode 100644 src/test/hotplug/disk-remove-lsi-last-slot.conf
 create mode 100644 src/test/hotplug/disk-remove-lsi-last-slot.conf.expected
 create mode 100644 src/test/hotplug/disk-remove-lsi-second-controller.conf
 create mode 100644 src/test/hotplug/disk-remove-lsi-second-controller.conf.expected

diff --git a/src/PVE/QemuServer.pm b/src/PVE/QemuServer.pm
index b4a1a38d..6ac3c685 100644
--- a/src/PVE/QemuServer.pm
+++ b/src/PVE/QemuServer.pm
@@ -4144,15 +4144,10 @@ sub qemu_deletescsihw {
 
     my $devices_list = vm_devices_list($vmid);
     foreach my $opt (keys %{$devices_list}) {
-        if (is_valid_drivename($opt)) {
-            my $drive = parse_drive($opt, $conf->{$opt});
-            if (
-                $drive->{interface} eq 'scsi'
-                && $drive->{index} < (($maxdev - 1) * ($controller + 1))
-            ) {
-                return 1;
-            }
-        }
+        next if $opt !~ m/^scsi(\d+)$/;
+        my $index = $1;
+        my (undef, $drive_controller) = scsihw_infos($conf->{scsihw}, $index);
+        return 1 if $drive_controller == $controller;
     }
 
     my $scsihwid = "scsihw$controller";
diff --git a/src/test/hotplug/disk-remove-lsi-last-slot.conf b/src/test/hotplug/disk-remove-lsi-last-slot.conf
new file mode 100644
index 00000000..aa50098b
--- /dev/null
+++ b/src/test/hotplug/disk-remove-lsi-last-slot.conf
@@ -0,0 +1,16 @@
+# TEST: hot-unplug a SCSI disk keeps the LSI controller if a disk in its last slot still uses it
+bootdisk: scsi6
+cores: 2
+machine: pc-i440fx-10.1
+memory: 2048
+name: hotplug
+net0: virtio=A2:C0:43:77:08:A0,bridge=vmbr0
+ostype: l26
+scsi0: local:8006/vm-8006-disk-0.qcow2,size=32G
+scsi6: local:8006/vm-8006-disk-1.qcow2,size=32G
+smbios1: uuid=7b10d7af-b932-4c66-b2c3-3996152ec465
+sockets: 1
+vmgenid: c773c261-d800-4348-9f5d-167fadd53cf8
+
+[PENDING]
+delete: scsi0
diff --git a/src/test/hotplug/disk-remove-lsi-last-slot.conf.expected b/src/test/hotplug/disk-remove-lsi-last-slot.conf.expected
new file mode 100644
index 00000000..e24d5479
--- /dev/null
+++ b/src/test/hotplug/disk-remove-lsi-last-slot.conf.expected
@@ -0,0 +1,3 @@
+hmp device_del scsi0
+qmp blockdev-del {"node-name":"drive-scsi0"}
+qmp object-del {"id":"throttle-drive-scsi0"}
diff --git a/src/test/hotplug/disk-remove-lsi-second-controller.conf b/src/test/hotplug/disk-remove-lsi-second-controller.conf
new file mode 100644
index 00000000..fc32cda6
--- /dev/null
+++ b/src/test/hotplug/disk-remove-lsi-second-controller.conf
@@ -0,0 +1,16 @@
+# TEST: hot-unplug the last SCSI disk of the second LSI controller also removes that controller
+bootdisk: scsi0
+cores: 2
+machine: pc-i440fx-10.1
+memory: 2048
+name: hotplug
+net0: virtio=A2:C0:43:77:08:A0,bridge=vmbr0
+ostype: l26
+scsi0: local:8006/vm-8006-disk-0.qcow2,size=32G
+scsi7: local:8006/vm-8006-disk-1.qcow2,size=32G
+smbios1: uuid=7b10d7af-b932-4c66-b2c3-3996152ec465
+sockets: 1
+vmgenid: c773c261-d800-4348-9f5d-167fadd53cf8
+
+[PENDING]
+delete: scsi7
diff --git a/src/test/hotplug/disk-remove-lsi-second-controller.conf.expected b/src/test/hotplug/disk-remove-lsi-second-controller.conf.expected
new file mode 100644
index 00000000..1287300a
--- /dev/null
+++ b/src/test/hotplug/disk-remove-lsi-second-controller.conf.expected
@@ -0,0 +1,4 @@
+hmp device_del scsi7
+qmp blockdev-del {"node-name":"drive-scsi7"}
+qmp object-del {"id":"throttle-drive-scsi7"}
+hmp device_del scsihw1
-- 
2.47.3