fix extend queue file path

qemeventd: handle threshold event

src/PVE/QemuServer.pm

@@ -5822,6 +5822,28 @@ sub vm_start_nolock {
         warn $@ if $@;
     }
 
+    # set write threshold for LVM thin provisioning disks
+    PVE::QemuConfig->foreach_volume(
+        $conf,
+        sub {
+            my ($ds, $drive) = @_;
+            return if PVE::QemuServer::drive_is_cdrom($drive, 1);
+            my $volid = $drive->{file};
+            if ( $volid ne 'none') {
+                my $extra_blockdev_options = {};
+                # $extra_blockdev_options->{'live-restore'} = $live_restore if $live_restore;
+                # extra protection for templates, but SATA and IDE don't support it..
+                $extra_blockdev_options->{'read-only'} = 1
+                    if drive_is_read_only($conf, $drive);
+
+                my $drive_id = PVE::QemuServer::Drive::get_drive_id($drive);
+                PVE::QemuServer::Blockdev::set_write_threshold(
+                    $storecfg, $vmid, $drive_id, $volid, $extra_blockdev_options,
+                );
+            }
+        },
+    );
+
     #start nbd server for storage migration
     if (my $nbd = $migrate_opts->{nbd}) {
 

src/PVE/QemuServer/Blockdev.pm

@@ -17,6 +17,7 @@ use PVE::QemuServer::Drive qw(drive_is_cdrom);
 use PVE::QemuServer::Helpers;
 use PVE::QemuServer::Machine;
 use PVE::QemuServer::Monitor qw(mon_cmd);
+use PVE::SafeSyslog;
 
 # gives ($host, $port, $export)
 my $NBD_TCP_PATH_RE_3 = qr/nbd:(\S+):(\d+):exportname=(\S+)/;
@@ -111,6 +112,21 @@ sub get_block_info {
     return $block_info;
 }
 
+sub get_block_stats {
+    my ($vmid) = @_;
+
+    my $block_stats = {};
+
+    my $qmp_block_stats = mon_cmd($vmid, "query-blockstats");
+    for my $info ($qmp_block_stats->@*) {
+        my $qdev_id = $info->{qdev} or next;
+        my $drive_id = qdev_id_to_drive_id($qdev_id);
+        $block_stats->{$drive_id} = $info;
+    }
+
+    return $block_stats;
+}
+
 my sub get_node_name {
     my ($type, $drive_id, $volid, $options) = @_;
 
@@ -700,6 +716,22 @@ sub resize {
     );
 }
 
+sub underlay_resize {
+    my ($storecfg, $vmid, $drive_id, $volid) = @_;
+
+    my $running = PVE::QemuServer::Helpers::vm_running_locally($vmid);
+
+    my $size = PVE::Storage::volume_underlay_resize($storecfg, $volid);
+    syslog("info", "got size $size KiB\n");
+
+    return if !$running;
+    my $block_info = get_block_info($vmid);
+    my $inserted = $block_info->{$drive_id}->{inserted}
+        or die "no block node inserted for drive '$drive_id'\n";
+
+    set_write_threshold($storecfg, $vmid, $drive_id, $volid);
+}
+
 my sub blockdev_change_medium {
     my ($storecfg, $vmid, $qdev_id, $drive) = @_;
 
@@ -820,6 +852,59 @@ sub set_io_throttle {
     }
 }
 
+sub block_set_write_threshold {
+    my ($vmid, $nodename, $threshold) = @_;
+
+    print "set threshold $nodename $threshold\n";
+
+    PVE::QemuServer::mon_cmd(
+        $vmid,
+        "block-set-write-threshold",
+        'node-name' => $nodename,
+        'write-threshold' => int($threshold),
+    );
+}
+
+sub compute_write_threshold {
+    my ($storecfg, $volid) = @_;
+
+    my $lv_size = PVE::Storage::volume_underlay_size_info($storecfg, $volid, 5);
+
+    # FIX: change these vars to config inputs
+    my $chunksize = 1024 * 1024 * 1024; # 1 GiB
+    my $alert_chunk_percentage = 0.5; # alert when percetage of chunk used
+
+    my $write_threshold = $lv_size - $chunksize * (1 - $alert_chunk_percentage);
+
+    return $write_threshold;
+}
+
+sub set_write_threshold {
+    my ($storecfg, $vmid, $drive_id, $volid, $options) = @_;
+
+    my ($storeid) = PVE::Storage::parse_volume_id($volid);
+    my $scfg = PVE::Storage::storage_config($storecfg, $storeid);
+    my $support_qemu_snapshots = PVE::Storage::volume_qemu_snapshot_method($storecfg, $volid);
+
+    # set write threshold is only supported for lvm storage using
+    # qcow2+external snapshots
+    return if $scfg->{type} ne 'lvm' || $support_qemu_snapshots ne 'mixed';
+    # return if drive is not set as thin
+    # return if !$drive->{thin};
+
+    print "setting threshold for $volid from $storeid\n";
+
+    my $snapshots = PVE::Storage::volume_snapshot_info($storecfg, $volid);
+    my $parentid = $snapshots->{'current'}->{parent};
+    # for now only set write_threshold for volumes that have snapshots
+    if ($parentid) {
+        my $nodename = get_node_name('file', $drive_id, $volid, $options);
+        my $write_threshold = compute_write_threshold($storecfg, $volid);
+
+        block_set_write_threshold($vmid, $nodename, $write_threshold);
+    }
+}
+
 sub blockdev_external_snapshot {
     my ($storecfg, $vmid, $machine_version, $deviceid, $drive, $snap, $parent_snap) = @_;
 
@@ -868,6 +953,9 @@ sub blockdev_external_snapshot {
         node => $snap_fmt_blockdev->{'node-name'},
         overlay => $new_fmt_blockdev->{'node-name'},
     );
+
+    my $drive_id = PVE::QemuServer::Drive::get_drive_id($drive);
+    set_write_threshold($storecfg, $vmid, $drive_id, $volid);
 }
 
 sub blockdev_delete {

src/PVE/QemuServer/Drive.pm

@@ -254,6 +254,13 @@ my %drivedesc_base = (
         optional => 1,
         default => 0,
     },
+    thin => {
+        type => 'boolean',
+        description =>
+            'Controls whether a drive should be thin provisioned',
+        optional => 1,
+        default => 0,
+    },
 );
 
 my %iothread_fmt = (

src/qmeventd/docinfo.xml

@@ -0,0 +1,8 @@
+<!-- DocBook document information file for Proxmox VE asciidoc docs -->
+
+<authorgroup>
+  <corpauthor>Proxmox Server Solutions Gmbh
+  <ulink url="https://www.proxmox.com/"><citetitle>www.proxmox.com</citetitle></ulink>
+  </corpauthor>
+</authorgroup>
+

src/qmeventd/pve-copyright.adoc

@@ -0,0 +1,18 @@
+Copyright and Disclaimer
+------------------------
+
+Copyright (C) 2007-2022 Proxmox Server Solutions GmbH
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as
+published by the Free Software Foundation, either version 3 of the
+License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public
+License along with this program.  If not, see
+https://www.gnu.org/licenses/

src/qmeventd/qmeventd.8

@@ -0,0 +1,80 @@
+'\" t
+.\"     Title: qmeventd
+.\"    Author: Proxmox Server Solutions Gmbh \m[blue]\fBwww.proxmox.com\fR\m[]
+.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
+.\"      Date: Fri Aug 15 05:33:35 PM WEST 2025
+.\"    Manual: Proxmox VE Documentation
+.\"    Source: \ \& 9.0.8
+.\"  Language: English
+.\"
+.TH "QMEVENTD" "8" "Fri Aug 15 05:33:35 PM WEST 2025" "\ \& 9\&.0\&.8" "Proxmox VE Documentation"
+.\" -----------------------------------------------------------------
+.\" * Define some portability stuff
+.\" -----------------------------------------------------------------
+.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.\" http://bugs.debian.org/507673
+.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
+.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.\" -----------------------------------------------------------------
+.\" * set default formatting
+.\" -----------------------------------------------------------------
+.\" disable hyphenation
+.nh
+.\" disable justification (adjust text to left margin only)
+.ad l
+.\" -----------------------------------------------------------------
+.\" * MAIN CONTENT STARTS HERE *
+.\" -----------------------------------------------------------------
+.SH "NAME"
+qmeventd \- PVE QEMU Eventd Daemon
+.SH "SYNOPSIS"
+.sp
+\fBqmeventd\fR [\-f] [\-v] PATH
+.PP
+\-v
+.RS 4
+Turn on verbose messages
+.RE
+.PP
+\-f
+.RS 4
+Do not daemonize server
+.RE
+.PP
+PATH
+.RS 4
+The path to listen on
+.RE
+.sp
+This service is usually started and managed using systemd toolset\&. The service is called \fIqmeventd\fR\&.
+.sp
+.nf
+systemctl start qmeventd
+.fi
+.sp
+.nf
+systemctl stop qmeventd
+.fi
+.sp
+.nf
+systemctl status qmeventd
+.fi
+.SH "DESCRIPTION"
+.sp
+qmeventd is a daemon that listens on PATH for incoming connections from a qemu qmp socket, and waits for SHUTDOWN events\&. When a client then disconnects, it executes /usr/sbin/qm cleanup\&. This makes it easy to clean up leftover tap devices, vgpus, etc\&.
+.SH "COPYRIGHT AND DISCLAIMER"
+.sp
+Copyright \(co 2007\-2022 Proxmox Server Solutions GmbH
+.sp
+This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version\&.
+.sp
+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE\&. See the GNU Affero General Public License for more details\&.
+.sp
+You should have received a copy of the GNU Affero General Public License along with this program\&. If not, see \m[blue]\fBhttps://www\&.gnu\&.org/licenses/\fR\m[]
+.SH "AUTHOR"
+.PP
+\fBProxmox Server Solutions Gmbh
+  \fR\fB\m[blue]\fBwww\&.proxmox\&.com\fR\m[]\fR\fB
+  \fR

src/qmeventd/qmeventd.8-synopsis.adoc

@@ -0,0 +1,16 @@
+*qmeventd* `[-f]` `[-v]` `PATH`
+
+`-v`:: Turn on verbose messages
+
+`-f`:: Do not daemonize server
+
+`PATH`:: The path to listen on
+
+This service is usually started and managed using systemd toolset. The
+service is called 'qmeventd'.
+
+ systemctl start qmeventd
+
+ systemctl stop qmeventd
+
+ systemctl status qmeventd

src/qmeventd/qmeventd.adoc

@@ -0,0 +1,32 @@
+ifdef::manvolnum[]
+qmeventd(8)
+===========
+:pve-toplevel:
+
+NAME
+----
+
+qmeventd - PVE QEMU Eventd Daemon
+
+SYNOPSIS
+--------
+
+include::qmeventd.8-synopsis.adoc[]
+
+DESCRIPTION
+-----------
+endif::manvolnum[]
+
+ifndef::manvolnum[]
+PVE QEMU Event Daemon
+=====================
+endif::manvolnum[]
+
+`qmeventd` is a daemon that listens on PATH for incoming connections from
+a qemu qmp socket, and waits for SHUTDOWN events. When a client then
+disconnects, it executes `/usr/sbin/qm cleanup`. This makes it easy
+to clean up leftover tap devices, vgpus, etc.
+
+ifdef::manvolnum[]
+include::pve-copyright.adoc[]
+endif::manvolnum[]

src/qmeventd/qmeventd.c

@@ -43,7 +43,7 @@
 
 #define DEFAULT_KILL_TIMEOUT 60
 
-static int verbose = 0;
+static int verbose = 1;
 static int kill_timeout = DEFAULT_KILL_TIMEOUT;
 static int epoll_fd = 0;
 static const char *progname;
@@ -209,6 +209,25 @@ void handle_qmp_event(struct Client *client, struct json_object *obj) {
 
         // check if a backup is running and kill QEMU process if not
         terminate_check(client);
+    } else if (!strcmp(json_object_get_string(event), "BLOCK_WRITE_THRESHOLD")) {
+        struct json_object *data;
+        struct json_object *nodename;
+        if (json_object_object_get_ex(obj, "data", &data) &&
+            json_object_object_get_ex(data, "node-name", &nodename)) {
+
+            // needs concurrency control
+            char extend_queue_path[] = "/etc/pve/extend-queue";
+            FILE *p_extend_queue = fopen(extend_queue_path, "a");
+            if (p_extend_queue == NULL) {
+                VERBOSE_PRINT(
+                    "%s: Couldn't open extend queue file %s", client->qemu.vmid, extend_queue_path
+                );
+            } else {
+                const char *nodename_string = json_object_get_string(nodename);
+                fprintf(p_extend_queue, "%s: %s\n", client->qemu.vmid, nodename_string);
+            }
+            fclose(p_extend_queue);
+        }
     }
 }