[pve-devel] [PATCH qemu-server 05/31] blockdev: add helpers for attaching and detaching block devices

[Fiona Ebner]

Signed-off-by: Fiona Ebner <f.ebner at proxmox.com>
---
 src/PVE/QemuServer/Blockdev.pm | 132 +++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)

diff --git a/src/PVE/QemuServer/Blockdev.pm b/src/PVE/QemuServer/Blockdev.pm
index 6e6b9245..26d70eee 100644
--- a/src/PVE/QemuServer/Blockdev.pm
+++ b/src/PVE/QemuServer/Blockdev.pm
@@ -11,6 +11,7 @@ use PVE::JSONSchema qw(json_bool);
 use PVE::Storage;
 
 use PVE::QemuServer::Drive qw(drive_is_cdrom);
+use PVE::QemuServer::Monitor qw(mon_cmd);
 
 my sub get_node_name {
     my ($type, $drive_id, $volid, $snap) = @_;
@@ -221,4 +222,135 @@ sub generate_drive_blockdev {
     };
 }
 
+my sub blockdev_add {
+    my ($vmid, $blockdev) = @_;
+
+    eval { mon_cmd($vmid, 'blockdev-add', $blockdev->%*); };
+    if (my $err = $@) {
+        my $node_name = $blockdev->{'node-name'} // 'undefined';
+        die "adding blockdev '$node_name' failed : $err\n" if $@;
+    }
+
+    return;
+}
+
+=pod
+
+=head3 attach
+
+    attach($storecfg, $vmid, $drive, $options);
+
+Attach the drive C<$drive> to the VM C<$vmid> considering the additional options C<$options>.
+
+Parameters:
+
+=over
+
+=item C<$storecfg>
+
+The storage configuration.
+
+=item C<$vmid>
+
+The ID of the virtual machine.
+
+=item C<$drive>
+
+The drive as parsed from a virtual machine configuration.
+
+=item C<$options>
+
+A hash reference with additional options.
+
+=over
+
+=item C<< $options->{'read-only'} >>
+
+Attach the image as read-only irrespective of the configuration in C<$drive>.
+
+=item C<< $options->{size} >>
+
+Attach the image with this virtual size. Must be smaller than the actual size of the image. The
+image format must be C<raw>.
+
+=item C<< $options->{'snapshot-name'} >>
+
+Attach this snapshot of the volume C<< $drive->{file} >>, rather than the volume itself.
+
+=back
+
+=back
+
+=cut
+
+sub attach {
+    my ($storecfg, $vmid, $drive, $options) = @_;
+
+    my $blockdev = generate_drive_blockdev($storecfg, $drive, $options);
+
+    my $drive_id = PVE::QemuServer::Drive::get_drive_id($drive);
+    if ($blockdev->{'node-name'} eq "drive-$drive_id") { # device top nodes need a throttle group
+        my $throttle_group = generate_throttle_group($drive);
+        mon_cmd($vmid, 'object-add', $throttle_group->%*);
+    }
+
+    eval { blockdev_add($vmid, $blockdev); };
+    if (my $err = $@) {
+        eval { mon_cmd($vmid, 'object-del', id => "throttle-drive-$drive_id"); };
+        warn $@ if $@;
+        die $err;
+    }
+
+    return;
+}
+
+=pod
+
+=head3 detach
+
+    detach($vmid, $node_name);
+
+Detach the block device C<$node_name> from the VM C<$vmid>. Also removes associated child block
+nodes.
+
+Parameters:
+
+=over
+
+=item C<$vmid>
+
+The ID of the virtual machine.
+
+=item C<$node_name>
+
+The node name identifying the block node in QEMU.
+
+=back
+
+=cut
+
+sub detach {
+    my ($vmid, $node_name) = @_;
+
+    die "Blockdev::detach - no node name\n" if !$node_name;
+
+    # QEMU recursively auto-removes the file children, i.e. file and format node below the top
+    # node and also implicit backing children referenced by a qcow2 image.
+    eval { mon_cmd($vmid, 'blockdev-del', 'node-name' => "$node_name"); };
+    if (my $err = $@) {
+        return if $err =~ m/Failed to find node with node-name/; # already gone
+        die "deleting blockdev '$node_name' failed : $err\n";
+    }
+
+    if ($node_name =~ m/^drive-(.+)$/) {
+        # also remove throttle group if it was a device top node
+        my $drive_id = $1;
+        if (PVE::QemuServer::Drive::is_valid_drivename($drive_id)) {
+            mon_cmd($vmid, 'object-del', id => "throttle-drive-$drive_id");
+        }
+    }
+
+    return;
+}
+
 1;
-- 
2.47.2