Important thing for bitmap migration is to select destination block
node to obtain the migrated bitmap.
Prepatch, on source we use bdrv_get_device_or_node_name() to identify
the node, and on target we do bdrv_lookup_bs.
bdrv_get_device_or_node_name() returns blk name only for direct
children of blk. So, bitmaps of direct children of blks are migrated by
blk name and others - by node name.
Old libvirt is unprepared to bitmap migration by node-name,
node-names are mostly auto-generated. So actually only migration by blk
name works for it.
Newer libvirt will use new interface (which will be added soon) to
specify node-mapping for bitmaps migration explicitly. Still, let's
improve the current behavior a bit.
Now, consider classic libvirt migrations assisted by mirror block job:
mirror block job inserts filter, so our source is not a direct child of
blk, and bitmaps are migrated by node-names. And this just doesn't work
with auto-generated node names.
Let's fix it by using blk-name even if some implicit filters are
inserted.
Note2: we, of course, can't skip filters and use blk name to migrate
bitmaps in filtered node by blk name for this blk if these filters have
named bitmaps which should be migrated.
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1652424
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
migration/block-dirty-bitmap.c | 45 +++++++++++++++++++++++++++++++++-
1 file changed, 44 insertions(+), 1 deletion(-)
diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 7e93718086..04a5525fd1 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -319,14 +319,54 @@ static int init_dirty_bitmap_migration(void)
{
BlockDriverState *bs;
DirtyBitmapMigBitmapState *dbms;
+ GHashTable *handled_by_blk = g_hash_table_new(NULL, NULL);
+ BlockBackend *blk;
dirty_bitmap_mig_state.bulk_completed = false;
dirty_bitmap_mig_state.prev_bs = NULL;
dirty_bitmap_mig_state.prev_bitmap = NULL;
dirty_bitmap_mig_state.no_bitmaps = false;
+ /*
+ * Use blockdevice name for direct (or filtered) children of named block
+ * backends.
+ */
+ for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
+ const char *name = blk_name(blk);
+
+ if (!name || strcmp(name, "") == 0) {
+ continue;
+ }
+
+ bs = blk_bs(blk);
+
+ /* Skip filters without bitmaos */
+ while (bs && bs->drv && bs->drv->is_filter &&
+ !bdrv_has_named_bitmaps(bs))
+ {
+ if (bs->backing) {
+ bs = bs->backing->bs;
+ } else if (bs->file) {
+ bs = bs->file->bs;
+ } else {
+ bs = NULL;
+ }
+ }
+
+ if (bs && bs->drv && !bs->drv->is_filter) {
+ if (add_bitmaps_to_list(bs, name)) {
+ goto fail;
+ }
+ g_hash_table_add(handled_by_blk, bs);
+ }
+ }
+
for (bs = bdrv_next_all_states(NULL); bs; bs = bdrv_next_all_states(bs)) {
- if (add_bitmaps_to_list(bs, bdrv_get_device_or_node_name(bs))) {
+ if (g_hash_table_contains(handled_by_blk, bs)) {
+ continue;
+ }
+
+ if (add_bitmaps_to_list(bs, bdrv_get_node_name(bs))) {
goto fail;
}
}
@@ -340,9 +380,12 @@ static int init_dirty_bitmap_migration(void)
dirty_bitmap_mig_state.no_bitmaps = true;
}
+ g_hash_table_destroy(handled_by_blk);
+
return 0;
fail:
+ g_hash_table_destroy(handled_by_blk);
dirty_bitmap_mig_cleanup();
return -1;
--
2.21.0