Allow setting user.* on the root disk when the VM is running

internal/server/device/config/devices.go

@@ -139,23 +139,13 @@ func (list Devices) Update(newlist Devices, updateFields func(Device, Device) []
 
 	// Detect which devices have changed or been removed in in new list.
 	for key, d := range list {
-		// Always skip user keys.
-		if strings.HasPrefix(key, "user.") {
-			continue
-		}
-
 		if !newlist.Contains(key, d) {
 			rmlist[key] = d
 		}
 	}
 
 	// Detect which devices have changed or been added in in new list.
 	for key, d := range newlist {
-		// Always skip user keys.
-		if strings.HasPrefix(key, "user.") {
-			continue
-		}
-
 		if !list.Contains(key, d) {
 			addlist[key] = d
 		}
@@ -172,6 +162,14 @@ func (list Devices) Update(newlist Devices, updateFields func(Device, Device) []
 		// Detect keys different between old and new device and append to the all changed keys list.
 		allChangedKeys = append(allChangedKeys, deviceEqualsDiffKeys(oldDevice, newDevice)...)
 
+		// Remove 'user.' fields that can be live-updated without adding/removing the device from instance.
+		for k := range d {
+			if strings.HasPrefix(k, "user.") {
+				delete(oldDevice, k)
+				delete(newDevice, k)
+			}
+		}
+
 		// Remove any fields that can be live-updated without adding/removing the device from instance.
 		if updateFields != nil {
 			for _, k := range updateFields(oldDevice, newDevice) {

internal/server/device/disk.go

@@ -1526,25 +1526,27 @@ func (d *disk) Update(oldDevices deviceConfig.Devices, isRunning bool) error {
 		}
 
 		if d.inst.Type() == instancetype.VM {
-			// Parse the limits into usable values.
-			readBps, readIops, writeBps, writeIops, err := d.parseLimit(d.config)
-			if err != nil {
-				return err
-			}
+			var diskLimits *deviceConfig.DiskLimits
+			runConf.Mounts = []deviceConfig.MountEntryItem{}
+			if d.config["limits.read"] != "" || d.config["limits.write"] != "" || d.config["limits.max"] != "" {
+				// Parse the limits into usable values.
+				readBps, readIops, writeBps, writeIops, err := d.parseLimit(d.config)
+				if err != nil {
+					return err
+				}
 
-			// Apply the limits to a minimal mount entry.
-			diskLimits := &deviceConfig.DiskLimits{
-				ReadBytes:  readBps,
-				ReadIOps:   readIops,
-				WriteBytes: writeBps,
-				WriteIOps:  writeIops,
-			}
+				// Apply the limits to a minimal mount entry.
+				diskLimits = &deviceConfig.DiskLimits{
+					ReadBytes:  readBps,
+					ReadIOps:   readIops,
+					WriteBytes: writeBps,
+					WriteIOps:  writeIops,
+				}
 
-			runConf.Mounts = []deviceConfig.MountEntryItem{
-				{
+				runConf.Mounts = append(runConf.Mounts, deviceConfig.MountEntryItem{
 					DevName: d.name,
 					Limits:  diskLimits,
-				},
+				})
 			}
 
 			oldAttached := util.IsTrueOrEmpty(oldDevices[d.name]["attached"])

internal/server/instance/drivers/driver_qemu.go

@@ -2487,7 +2487,7 @@ func (d *qemu) deviceStart(dev device.Device, instanceRunning bool) (*deviceConf
 					if err != nil {
 						return nil, err
 					}
-				} else {
+				} else if mount.TargetPath != "/" {
 					err = d.deviceAttachBlockDevice(dev.Name(), configCopy, mount)
 					if err != nil {
 						return nil, err