From 780525f32851c0daaf4250dc734ba73d1571c1c1 Mon Sep 17 00:00:00 2001
From: Felipe Borges <felipeborges@gnome.org>
Date: Mon, 2 Nov 2020 15:35:36 +0100
Subject: [PATCH] vm-configurator: Pass discard "unmap" to virtio-blk disks

Ever since QEMU 4.0, virtio-blk disks have discard support[0]. For
this reason, we don't need to migrate to virtio-scsi[1] to benefit from
discard support.

See also https://chrisirwin.ca/posts/discard-with-kvm-2020/

[0] https://bugzilla.redhat.com/1672680
[1] https://bugzilla.redhat.com/1152037

Fixes #35
---
 src/vm-configurator.vala | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/vm-configurator.vala b/src/vm-configurator.vala
index ee8cf133..f2a50bb8 100644
--- a/src/vm-configurator.vala
+++ b/src/vm-configurator.vala
@@ -343,16 +343,21 @@ public static void set_target_media_config (Domain         domain,
         var disk = new DomainDisk ();
         disk.set_type (DomainDiskType.FILE);
         disk.set_guest_device_type (DomainDiskGuestDeviceType.DISK);
-        disk.set_driver_name ("qemu");
-        disk.set_driver_format (DomainDiskFormat.QCOW2);
         disk.set_source (target_path);
-        disk.set_driver_cache (DomainDiskCacheType.WRITEBACK);
+
+        var driver = new DomainDiskDriver ();
+        driver.set_name ("qemu");
+        driver.set_format (DomainDiskFormat.QCOW2);
+        driver.set_cache (DomainDiskCacheType.WRITEBACK);
+        disk.set_driver (driver);
 
         var dev_letter_str = ((char) (dev_index + 97)).to_string ();
         if (install_media.supports_virtio_disk || install_media.supports_virtio1_disk) {
             debug ("Using virtio controller for the main disk");
             disk.set_target_bus (DomainDiskBus.VIRTIO);
             disk.set_target_dev ("vd" + dev_letter_str);
+
+            driver.set_discard (DomainDiskDriverDiscard.UNMAP);
         } else {
             if (install_media.prefers_q35) {
                 debug ("Using SATA controller for the main disk");
-- 
2.26.2