qemu: Translate the pool disk source when building drive string

This adds a new helper qemuTranslateDiskSourcePool which uses the
storage pool/vol APIs to translate the disk source before building
the drive string. Network volume is not supported yet. Disk chain
for volume type disk may be supported later, but before I'm confident
it doesn't break anything, it's just disabled now.

src/qemu/qemu_command.c

@@ -2681,6 +2681,49 @@ qemuBuildNBDString(virConnectPtr conn, virDomainDiskDefPtr disk, virBufferPtr op
     return 0;
 }
 
+static int
+qemuTranslateDiskSourcePool(virConnectPtr conn,
+                            virDomainDiskDefPtr def,
+                            int *voltype)
+{
+    virStoragePoolPtr pool = NULL;
+    virStorageVolPtr vol = NULL;
+    virStorageVolInfo info;
+    int ret = -1;
+
+    if (def->type != VIR_DOMAIN_DISK_TYPE_VOLUME)
+        return 0;
+
+    if (!(pool = virStoragePoolLookupByName(conn, def->srcpool->pool)))
+        return -1;
+
+    if (!(vol = virStorageVolLookupByName(pool, def->srcpool->volume)))
+        goto cleanup;
+
+    if (virStorageVolGetInfo(vol, &info) < 0)
+        goto cleanup;
+
+    switch (info.type) {
+    case VIR_STORAGE_VOL_FILE:
+    case VIR_STORAGE_VOL_BLOCK:
+    case VIR_STORAGE_VOL_DIR:
+        if (!(def->src = virStorageVolGetPath(vol)))
+            goto cleanup;
+        break;
+    case VIR_STORAGE_VOL_NETWORK:
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("Using network volume as disk source is not supported"));
+        goto cleanup;
+    }
+
+    *voltype = info.type;
+    ret = 0;
+cleanup:
+    virStoragePoolFree(pool);
+    virStorageVolFree(vol);
+    return ret;
+}
+
 char *
 qemuBuildDriveStr(virConnectPtr conn ATTRIBUTE_UNUSED,
                   virDomainDiskDefPtr disk,
@@ -2693,6 +2736,7 @@ qemuBuildDriveStr(virConnectPtr conn ATTRIBUTE_UNUSED,
         virDomainDiskGeometryTransTypeToString(disk->geometry.trans);
     int idx = virDiskNameToIndex(disk->dst);
     int busid = -1, unitid = -1;
+    int voltype = -1;
 
     if (idx < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
@@ -2700,6 +2744,9 @@ qemuBuildDriveStr(virConnectPtr conn ATTRIBUTE_UNUSED,
         goto error;
     }
 
+    if (qemuTranslateDiskSourcePool(conn, disk, &voltype) < 0)
+        goto error;
+
     switch (disk->bus) {
     case VIR_DOMAIN_DISK_BUS_SCSI:
         if (disk->info.type != VIR_DOMAIN_DEVICE_ADDRESS_TYPE_DRIVE) {
@@ -2834,6 +2881,38 @@ qemuBuildDriveStr(virConnectPtr conn ATTRIBUTE_UNUSED,
                 }
                 break;
             }
+        } else if (disk->type == VIR_DOMAIN_DISK_TYPE_VOLUME) {
+            switch (voltype) {
+            case VIR_STORAGE_VOL_DIR:
+                if (!disk->readonly) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                                   _("cannot create virtual FAT disks in read-write mode"));
+                    goto error;
+                }
+                if (disk->device == VIR_DOMAIN_DISK_DEVICE_FLOPPY)
+                    virBufferEscape(&opt, ',', ",", "file=fat:floppy:%s,",
+                                    disk->src);
+                else
+                    virBufferEscape(&opt, ',', ",", "file=fat:%s,", disk->src);
+                break;
+            case VIR_STORAGE_VOL_BLOCK:
+                if (disk->tray_status == VIR_DOMAIN_DISK_TRAY_OPEN) {
+                    virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                                   _("tray status 'open' is invalid for "
+                                     "block type volume"));
+                    goto error;
+                }
+                virBufferEscape(&opt, ',', ",", "file=%s,", disk->src);
+                break;
+            case VIR_STORAGE_VOL_FILE:
+                virBufferEscape(&opt, ',', ",", "file=%s,", disk->src);
+                break;
+            case VIR_STORAGE_VOL_NETWORK:
+                /* Keep the compiler quite, qemuTranslateDiskSourcePool already
+                 * reported the unsupported error.
+                 */
+                break;
+            }
         } else {
             if ((disk->type == VIR_DOMAIN_DISK_TYPE_BLOCK) &&
                 (disk->tray_status == VIR_DOMAIN_DISK_TRAY_OPEN)) {

src/qemu/qemu_domain.c

@@ -2037,7 +2037,9 @@ qemuDomainDetermineDiskChain(virQEMUDriverPtr driver,
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
     int ret = 0;
 
-    if (!disk->src || disk->type == VIR_DOMAIN_DISK_TYPE_NETWORK)
+    if (!disk->src ||
+        disk->type == VIR_DOMAIN_DISK_TYPE_NETWORK ||
+        disk->type == VIR_DOMAIN_DISK_TYPE_VOLUME)
         goto cleanup;
 
     if (disk->backingChain) {