blockdev-backup: add bitmap argument

It is only an oversight that we don't allow incremental backup with
blockdev-backup. Add the bitmap argument which enables this.
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Message-id: 20180830211605.13683-2-jsnow@redhat.com
Signed-off-by: NJohn Snow <jsnow@redhat.com>

blockdev.c

@@ -3545,6 +3545,7 @@ BlockJob *do_blockdev_backup(BlockdevBackup *backup, JobTxn *txn,
     BlockDriverState *bs;
     BlockDriverState *target_bs;
     Error *local_err = NULL;
+    BdrvDirtyBitmap *bmap = NULL;
     AioContext *aio_context;
     BlockJob *job = NULL;
     int job_flags = JOB_DEFAULT;
@@ -3595,6 +3596,21 @@ BlockJob *do_blockdev_backup(BlockdevBackup *backup, JobTxn *txn,
             goto out;
         }
     }
+
+    if (backup->has_bitmap) {
+        bmap = bdrv_find_dirty_bitmap(bs, backup->bitmap);
+        if (!bmap) {
+            error_setg(errp, "Bitmap '%s' could not be found", backup->bitmap);
+            goto out;
+        }
+        if (bdrv_dirty_bitmap_qmp_locked(bmap)) {
+            error_setg(errp,
+                       "Bitmap '%s' is currently locked and cannot be used for "
+                       "backup", backup->bitmap);
+            goto out;
+        }
+    }
+
     if (!backup->auto_finalize) {
         job_flags |= JOB_MANUAL_FINALIZE;
     }
@@ -3602,7 +3618,7 @@ BlockJob *do_blockdev_backup(BlockdevBackup *backup, JobTxn *txn,
         job_flags |= JOB_MANUAL_DISMISS;
     }
     job = backup_job_create(backup->job_id, bs, target_bs, backup->speed,
-                            backup->sync, NULL, backup->compress,
+                            backup->sync, bmap, backup->compress,
                             backup->on_source_error, backup->on_target_error,
                             job_flags, NULL, NULL, txn, &local_err);
     if (local_err != NULL) {

qapi/block-core.json

@@ -1316,6 +1316,10 @@
 # @speed: the maximum speed, in bytes per second. The default is 0,
 #         for unlimited.
 #
+# @bitmap: the name of dirty bitmap if sync is "incremental".
+#          Must be present if sync is "incremental", must NOT be present
+#          otherwise. (Since 3.1)
+#
 # @compress: true to compress data, if the target format supports it.
 #            (default: false) (since 2.8)
 #
@@ -1348,7 +1352,8 @@
 ##
 { 'struct': 'BlockdevBackup',
   'data': { '*job-id': 'str', 'device': 'str', 'target': 'str',
-            'sync': 'MirrorSyncMode', '*speed': 'int', '*compress': 'bool',
+            'sync': 'MirrorSyncMode', '*speed': 'int',
+            '*bitmap': 'str', '*compress': 'bool',
             '*on-source-error': 'BlockdevOnError',
             '*on-target-error': 'BlockdevOnError',
             '*auto-finalize': 'bool', '*auto-dismiss': 'bool' } }