qemu: Supply correct default type for 'dir' based VIR_STORAGE_TYPE_VOLUME

Our code would skip adding the default type in this cases, but since we
know that the only reasonable option here is 'fat' we can add it while
starting the VM.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_domain.c

@@ -14217,10 +14217,16 @@ qemuDomainPrepareDiskSource(virDomainDiskDefPtr disk,
 {
     qemuDomainPrepareDiskCachemode(disk);
 
-    /* add raw file format if the storage pool did not fill it in */
+    /* set default format for storage pool based disks */
     if (disk->src->type == VIR_STORAGE_TYPE_VOLUME &&
-        disk->src->format <= VIR_STORAGE_FILE_NONE)
-        disk->src->format = VIR_STORAGE_FILE_RAW;
+        disk->src->format <= VIR_STORAGE_FILE_NONE) {
+        int actualType = virStorageSourceGetActualType(disk->src);
+
+        if (actualType == VIR_STORAGE_TYPE_DIR)
+            disk->src->format = VIR_STORAGE_FILE_FAT;
+        else
+            disk->src->format = VIR_STORAGE_FILE_RAW;
+    }
 
     if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV)) {
         if (qemuDomainPrepareDiskSourceBlockdev(disk, priv, cfg) < 0)

tests/qemuxml2argvdata/disk-source-pool.args

@@ -36,4 +36,8 @@ readonly=on \
 readonly=on \
 -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,\
 id=virtio-disk0 \
+-drive file=fat:/some/dir/device/vol2,if=none,id=drive-virtio-disk1,\
+readonly=on \
+-device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk1,\
+id=virtio-disk1 \
 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3

tests/qemuxml2argvdata/disk-source-pool.xml

@@ -43,6 +43,12 @@
       <target dev='vda' bus='virtio'/>
       <readonly/>
     </disk>
+    <disk type='volume' device='disk'>
+      <driver name='qemu'/>
+      <source pool='pool-disk' volume='dir+vol2'/>
+      <target dev='vdb' bus='virtio'/>
+      <readonly/>
+    </disk>
     <controller type='usb' index='0'/>
     <controller type='ide' index='0'/>
     <controller type='pci' index='0' model='pci-root'/>

tests/qemuxml2xmloutdata/disk-source-pool.xml

@@ -44,6 +44,13 @@
       <readonly/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
     </disk>
+    <disk type='volume' device='disk'>
+      <driver name='qemu'/>
+      <source pool='pool-disk' volume='dir+vol2'/>
+      <target dev='vdb' bus='virtio'/>
+      <readonly/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
+    </disk>
     <controller type='usb' index='0'>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
     </controller>