[pve-devel] [RFC qemu-server 5/7] api: move-disk: add move to other VM

[Aaron Lauterer <a.lauterer@proxmox.com>]

The goal of this is to expand the move-disk API endpoint to make it
possible to move a disk to another VM. Previously this was only possible
with manual intervertion either by renaming the VM disk or by manually
adding the disks volid to the config of the other VM.

Signed-off-by: Aaron Lauterer <a.lauterer@proxmox.com>
---

There are some big changes here. The old [0] dedicated API endpoint is
gone and most of its code is now part of move_disk. Error messages have
been changed accordingly and sometimes enahnced by adding disk keys and
VMIDs where appropriate.

Since a move to other guests should be possible for unused disks, we
need to check before doing a move to storage to make sure to not
handle unused disks.

[0] https://lists.proxmox.com/pipermail/pve-devel/2021-April/047738.html

 PVE/API2/Qemu.pm | 204 +++++++++++++++++++++++++++++++++++++++++++++--
 PVE/CLI/qm.pm    |   2 +-
 2 files changed, 200 insertions(+), 6 deletions(-)

diff --git a/PVE/API2/Qemu.pm b/PVE/API2/Qemu.pm
index 24dba86..f1aee8d 100644
--- a/PVE/API2/Qemu.pm
+++ b/PVE/API2/Qemu.pm
@@ -35,6 +35,7 @@ use PVE::API2::Qemu::Agent;
 use PVE::VZDump::Plugin;
 use PVE::DataCenterConfig;
 use PVE::SSHInfo;
+use PVE::Replication;
 
 BEGIN {
     if (!$ENV{PVE_GENERATING_DOCS}) {
@@ -3258,9 +3259,11 @@ __PACKAGE__->register_method({
     method => 'POST',
     protected => 1,
     proxyto => 'node',
-    description => "Move volume to different storage.",
+    description => "Move volume to different storage or to a different VM.",
     permissions => {
-	description => "You need 'VM.Config.Disk' permissions on /vms/{vmid}, and 'Datastore.AllocateSpace' permissions on the storage.",
+	description => "You need 'VM.Config.Disk' permissions on /vms/{vmid}, " .
+	    "and 'Datastore.AllocateSpace' permissions on the storage. To move ".
+	    "a disk to another VM, you need the permissions on the target VM as well.",
 	check => [ 'and',
 		   ['perm', '/vms/{vmid}', [ 'VM.Config.Disk' ]],
 		   ['perm', '/storage/{storage}', [ 'Datastore.AllocateSpace' ]],
@@ -3271,14 +3274,19 @@ __PACKAGE__->register_method({
 	properties => {
 	    node => get_standard_option('pve-node'),
 	    vmid => get_standard_option('pve-vmid', { completion => \&PVE::QemuServer::complete_vmid }),
+	    'target-vmid' => get_standard_option('pve-vmid', {
+		completion => \&PVE::QemuServer::complete_vmid,
+		optional => 1,
+	    }),
 	    disk => {
 	        type => 'string',
 		description => "The disk you want to move.",
-		enum => [PVE::QemuServer::Drive::valid_drive_names()],
+		enum => [PVE::QemuServer::Drive::valid_drive_names_with_unused()],
 	    },
             storage => get_standard_option('pve-storage-id', {
 		description => "Target storage.",
 		completion => \&PVE::QemuServer::complete_storage,
+		optional => 1,
             }),
             'format' => {
                 type => 'string',
@@ -3305,6 +3313,18 @@ __PACKAGE__->register_method({
 		minimum => '0',
 		default => 'move limit from datacenter or storage config',
 	    },
+	    'target-disk' => {
+	        type => 'string',
+		description => "The config key the disk will be moved to on the target VM (for example, ide0 or scsi1).",
+		enum => [PVE::QemuServer::Drive::valid_drive_names_with_unused()],
+		optional => 1,
+	    },
+	    'target-digest' => {
+		type => 'string',
+		description => 'Prevent changes if current configuration file of the target VM has a different SHA1 digest. This can be used to prevent concurrent modifications.',
+		maxLength => 40,
+		optional => 1,
+	    },
 	},
     },
     returns => {
@@ -3319,14 +3339,22 @@ __PACKAGE__->register_method({
 
 	my $node = extract_param($param, 'node');
 	my $vmid = extract_param($param, 'vmid');
+	my $target_vmid = extract_param($param, 'target-vmid');
 	my $digest = extract_param($param, 'digest');
+	my $target_digest = extract_param($param, 'target-digest');
 	my $disk = extract_param($param, 'disk');
+	my $target_disk = extract_param($param, 'target-disk');
 	my $storeid = extract_param($param, 'storage');
 	my $format = extract_param($param, 'format');
 
+	die "either set storage or target-vmid, but not both\n"
+	    if $storeid && $target_vmid;
+
+
 	my $storecfg = PVE::Storage::config();
+	my $source_volid;
 
-	my $updatefn =  sub {
+	my $move_updatefn =  sub {
 	    my $conf = PVE::QemuConfig->load_config($vmid);
 	    PVE::QemuConfig->check_lock($conf);
 
@@ -3436,7 +3464,173 @@ __PACKAGE__->register_method({
             return $rpcenv->fork_worker('qmmove', $vmid, $authuser, $realcmd);
 	};
 
-	return PVE::QemuConfig->lock_config($vmid, $updatefn);
+	my $load_and_check_reassign_configs = sub {
+	    my $vmlist = PVE::Cluster::get_vmlist()->{ids};
+	    die "Both VMs need to be on the same node ($vmlist->{$vmid}->{node}) but target VM is on $vmlist->{$target_vmid}->{node}.\n"
+		if $vmlist->{$vmid}->{node} ne $vmlist->{$target_vmid}->{node};
+
+	    my $source_conf = PVE::QemuConfig->load_config($vmid);
+	    PVE::QemuConfig->check_lock($source_conf);
+	    my $target_conf = PVE::QemuConfig->load_config($target_vmid);
+	    PVE::QemuConfig->check_lock($target_conf);
+
+	    die "Can't move disks from or to template VMs\n"
+		if ($source_conf->{template} || $target_conf->{template});
+
+	    if ($digest) {
+		eval { PVE::Tools::assert_if_modified($digest, $source_conf->{digest}) };
+		if (my $err = $@) {
+		    die "VM ${vmid}: ${err}";
+		}
+	    }
+
+	    if ($target_digest) {
+		eval { PVE::Tools::assert_if_modified($target_digest, $target_conf->{digest}) };
+		if (my $err = $@) {
+		    die "VM ${target_vmid}: ${err}";
+		}
+	    }
+
+	    die "Disk '${disk}' for VM '$vmid' does not exist\n"
+		if !defined($source_conf->{$disk});
+
+	    die "Target disk key '${target_disk}' is already in use for VM '$target_vmid'\n"
+		if exists $target_conf->{$target_disk};
+
+	    my $drive = PVE::QemuServer::parse_drive(
+		$disk,
+		$source_conf->{$disk},
+	    );
+	    $source_volid = $drive->{file};
+
+	    die "disk '${disk}' has no associated volume\n"
+		if !$source_volid;
+	    die "CD drive contents can't be moved to another VM\n"
+		if PVE::QemuServer::drive_is_cdrom($drive, 1);
+	    die "Can't move  physical disk to another VM\n" if $drive->{file} =~ m|^/dev/|;
+	    die "Can't move disk used by a snapshot to another VM\n"
+		if PVE::QemuServer::Drive::is_volume_in_use(
+		    $storecfg,
+		    $source_conf,
+		    $disk,
+		    $source_volid,
+		);
+
+	    die "Storage does not support moving of this disk to another VM\n"
+		if !PVE::Storage::volume_has_feature(
+		    $storecfg,
+		    'rename',
+		    $source_volid,
+		);
+
+	    die "Cannot move disk to another VM while the source VM is running\n"
+		if PVE::QemuServer::check_running($vmid)
+		    && $disk !~ m/^unused\d+$/;
+
+	    if ($target_disk !~ m/^unused\d+$/ && $target_disk =~ m/^([^\d]+)\d+$/) {
+		my $interface = $1;
+		my $desc = PVE::JSONSchema::get_standard_option("pve-qm-${interface}");
+		eval {
+		    PVE::JSONSchema::parse_property_string(
+			$desc->{format},
+			$source_conf->{$disk},
+		    )
+		};
+		if (my $err = $@) {
+		    die "Cannot move disk to another VM: ${err}";
+		}
+	    }
+
+	    return ($source_conf, $target_conf);
+	};
+
+	my $logfunc = sub {
+	    my ($msg) = @_;
+	    print STDERR "$msg\n";
+	};
+
+	my $disk_reassignfn = sub {
+	    return PVE::QemuConfig->lock_config($vmid, sub {
+		return PVE::QemuConfig->lock_config($target_vmid, sub {
+		    my ($source_conf, $target_conf) = &$load_and_check_reassign_configs();
+
+		    my $drive_param = PVE::QemuServer::parse_drive(
+			$target_disk,
+			$source_conf->{$disk},
+		    );
+
+		    print "moving disk '$disk' from VM '$vmid' to '$target_vmid'\n";
+		    my ($storeid, undef) = PVE::Storage::parse_volume_id($source_volid);
+
+		    my $target_volname = PVE::Storage::find_free_diskname($storecfg, $storeid, $target_vmid, $format);
+
+		    my $new_volid = PVE::Storage::rename_volume(
+			$storecfg,
+			$source_volid,
+			$vmid,
+			$target_volname,
+			$target_vmid,
+		    );
+
+		    $drive_param->{file} = $new_volid;
+
+		    delete $source_conf->{$disk};
+		    print "removing disk '${disk}' from VM '${vmid}' config\n";
+		    PVE::QemuConfig->write_config($vmid, $source_conf);
+
+		    my $drive_string = PVE::QemuServer::print_drive($drive_param);
+		    &$update_vm_api(
+			{
+			    node => $node,
+			    vmid => $target_vmid,
+			    digest => $target_digest,
+			    $target_disk => $drive_string,
+			},
+			1,
+		    );
+
+		    # remove possible replication snapshots
+		    if (PVE::Storage::volume_has_feature(
+			    $storecfg,
+			    'replicate',
+			    $source_volid),
+		    ) {
+			eval {
+			    PVE::Replication::prepare(
+				$storecfg,
+				[$new_volid],
+				undef,
+				1,
+				undef,
+				$logfunc,
+			    )
+			};
+			if (my $err = $@) {
+			    print "Failed to remove replication snapshots on moved disk '$target_disk'. Manual cleanup could be necessary.\n";
+			}
+		    }
+		});
+	    });
+	};
+
+	if ($target_vmid) {
+	    $rpcenv->check_vm_perm($authuser, $target_vmid, undef, ['VM.Config.Disk'])
+		if $authuser ne 'root@pam';
+
+	    die "Moving a disk to the same VM is not possible. Did you mean to move the disk to a different storage?\n"
+		if $vmid eq $target_vmid;
+
+	    &$load_and_check_reassign_configs();
+	    return $rpcenv->fork_worker('qmmove', "${vmid}-${disk}>${target_vmid}-${target_disk}", $authuser, $disk_reassignfn);
+	} elsif ($storeid) {
+	    die "cannot move disk '$disk', only configured disks can be moved to another storage\n"
+		if $disk =~ m/^unused\d+$/;
+	    return PVE::QemuConfig->lock_config($vmid, $move_updatefn);
+	} else {
+	    die "Provide either a 'storage' to move the disk to a different " .
+		"storage or 'target-vmid' and 'target-disk' to move the disk " .
+		"to another VM\n";
+	}
     }});
 
 my $check_vm_disks_local = sub {
diff --git a/PVE/CLI/qm.pm b/PVE/CLI/qm.pm
index 60360c8..4b475f8 100755
--- a/PVE/CLI/qm.pm
+++ b/PVE/CLI/qm.pm
@@ -910,7 +910,7 @@ our $cmddef = {
 
     resize => [ "PVE::API2::Qemu", 'resize_vm', ['vmid', 'disk', 'size'], { node => $nodename } ],
 
-    'move-disk' => [ "PVE::API2::Qemu", 'move_vm_disk', ['vmid', 'disk', 'storage'], { node => $nodename }, $upid_exit ],
+    'move-disk' => [ "PVE::API2::Qemu", 'move_vm_disk', ['vmid', 'disk', 'storage', 'target-vmid', 'target-disk'], { node => $nodename }, $upid_exit ],
     move_disk => { alias => 'move-disk' },
 
     unlink => [ "PVE::API2::Qemu", 'unlink', ['vmid'], { node => $nodename } ],
-- 
2.20.1