qemu: Move virtual FAT disk validation from command line builder

Move it to the validation callback and make it more robust. This will
also put the checks in the correct place to use with -blockdev.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

src/qemu/qemu_command.c

@@ -1520,20 +1520,6 @@ qemuBuildDriveSourceStr(virDomainDiskDefPtr disk,
 
         /* for now the DIR based storage is handled by the magic FAT format */
         if (actualType == VIR_STORAGE_TYPE_DIR) {
-            if (disk->src->format > 0 &&
-                disk->src->format != VIR_STORAGE_FILE_FAT) {
-                virReportError(VIR_ERR_INTERNAL_ERROR,
-                               _("unsupported disk driver type for '%s'"),
-                               virStorageFileFormatTypeToString(disk->src->format));
-                goto cleanup;
-            }
-
-            if (!disk->src->readonly) {
-                virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                               _("cannot create virtual FAT disks in read-write mode"));
-                goto cleanup;
-            }
-
             virBufferAddLit(buf, "fat:");
 
             if (disk->device == VIR_DOMAIN_DISK_DEVICE_FLOPPY)

src/qemu/qemu_domain.c

@@ -4128,6 +4128,8 @@ static int
 qemuDomainValidateStorageSource(virStorageSourcePtr src,
                                 virQEMUCapsPtr qemuCaps)
 {
+    int actualType = virStorageSourceGetActualType(src);
+
     if (src->format == VIR_STORAGE_FILE_COW) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                       _("'cow' storage format is not supported"));
@@ -4157,6 +4159,29 @@ qemuDomainValidateStorageSource(virStorageSourcePtr src,
         return -1;
     }
 
+    if (src->format == VIR_STORAGE_FILE_FAT &&
+        actualType != VIR_STORAGE_TYPE_DIR) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("storage format 'fat' is supported only with 'dir' "
+                         "storage type"));
+        return -1;
+    }
+
+    if (actualType == VIR_STORAGE_TYPE_DIR) {
+        if (src->format > 0 &&
+            src->format != VIR_STORAGE_FILE_FAT) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("storage type 'dir' requires use of storage format 'fat'"));
+            return -1;
+        }
+
+        if (!src->readonly) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("virtual FAT storage can't be accessed in read-write mode"));
+            return -1;
+        }
+    }
+
     return 0;
 }