block/backup: Add mirror sync mode 'bitmap'

We don't need or want a new sync mode for simple differences in
semantics.  Create a new mode simply named "BITMAP" that is designed to
make use of the new Bitmap Sync Mode field.

Because the only bitmap sync mode is 'on-success', this adds no new
functionality to the backup job (yet). The old incremental backup mode
is maintained as a syntactic sugar for sync=bitmap, mode=on-success.

Add all of the plumbing necessary to support this new instruction.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190709232550.10724-6-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

1 files changed, 23 insertions, 2 deletions

diff --git a/blockdev.c b/blockdev.c
index 8e4f70a..985b6cd 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3466,12 +3466,31 @@ static BlockJob *do_backup_common(BackupCommon *backup,
         return NULL;
     }
 
+    if (backup->sync == MIRROR_SYNC_MODE_INCREMENTAL) {
+        if (backup->has_bitmap_mode &&
+            backup->bitmap_mode != BITMAP_SYNC_MODE_ON_SUCCESS) {
+            error_setg(errp, "Bitmap sync mode must be '%s' "
+                       "when using sync mode '%s'",
+                       BitmapSyncMode_str(BITMAP_SYNC_MODE_ON_SUCCESS),
+                       MirrorSyncMode_str(backup->sync));
+            return NULL;
+        }
+        backup->has_bitmap_mode = true;
+        backup->sync = MIRROR_SYNC_MODE_BITMAP;
+        backup->bitmap_mode = BITMAP_SYNC_MODE_ON_SUCCESS;
+    }
+
     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);
             return NULL;
         }
+        if (!backup->has_bitmap_mode) {
+            error_setg(errp, "Bitmap sync mode must be given "
+                       "when providing a bitmap");
+            return NULL;
+        }
         if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_DEFAULT, errp)) {
             return NULL;
         }
@@ -3485,8 +3504,10 @@ static BlockJob *do_backup_common(BackupCommon *backup,
     }
 
     job = backup_job_create(backup->job_id, bs, target_bs, backup->speed,
-                            backup->sync, bmap, backup->compress,
-                            backup->on_source_error, backup->on_target_error,
+                            backup->sync, bmap, backup->bitmap_mode,
+                            backup->compress,
+                            backup->on_source_error,
+                            backup->on_target_error,
                             job_flags, NULL, NULL, txn, errp);
     return job;
 }