block/backup: add 'never' policy to bitmap sync mode
This adds a "never" policy for bitmap synchronization. Regardless of if
the job succeeds or fails, we never update the bitmap. This can be used
to perform differential backups, or simply to avoid the job modifying a
bitmap.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190709232550.10724-7-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
diff --git a/block/backup.c b/block/backup.c
index 2b4c5c2..d07b838 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -274,8 +274,11 @@
BdrvDirtyBitmap *bm;
BlockDriverState *bs = blk_bs(job->common.blk);
- if (ret < 0) {
- /* Merge the successor back into the parent, delete nothing. */
+ if (ret < 0 || job->bitmap_mode == BITMAP_SYNC_MODE_NEVER) {
+ /*
+ * Failure, or we don't want to synchronize the bitmap.
+ * Merge the successor back into the parent, delete nothing.
+ */
bm = bdrv_reclaim_dirty_bitmap(bs, job->sync_bitmap, NULL);
assert(bm);
} else {
diff --git a/qapi/block-core.json b/qapi/block-core.json
index dd926f7..06e3448 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1146,10 +1146,13 @@
# @on-success: The bitmap is only synced when the operation is successful.
# This is the behavior always used for 'INCREMENTAL' backups.
#
+# @never: The bitmap is never synchronized with the operation, and is
+# treated solely as a read-only manifest of blocks to copy.
+#
# Since: 4.2
##
{ 'enum': 'BitmapSyncMode',
- 'data': ['on-success'] }
+ 'data': ['on-success', 'never'] }
##
# @MirrorCopyMode:
