@@ -1621,3 +1621,39 @@
##
{ 'event': 'UNPLUG_PRIMARY',
'data': { 'device-id': 'str' } }
+
+##
+# @MigrationBlockNodeMapping:
+#
+# Maps a block node name to an alias for migration.
+#
+# @node-name: A block node name.
+#
+# @alias: An alias name for migration (for example the node name on
+# the opposite site).
+#
+# Since: 5.1
+##
+{ 'struct': 'MigrationBlockNodeMapping',
+ 'data': {
+ 'node-name': 'str',
+ 'alias': 'str'
+ } }
+
+##
+# @migrate-set-bitmap-node-mapping:
+#
+# Maps block node names to arbitrary aliases for the purpose of dirty
+# bitmap migration. Such aliases may for example be the corresponding
+# node names on the opposite site.
+#
+# By default, every node name is mapped to itself.
+#
+# @mapping: The mapping; must be one-to-one, but not necessarily
+# complete. Any mapping not given will be reset to the
+# default (i.e. the identity mapping).
+#
+# Since: 5.1
+##
+{ 'command': 'migrate-set-bitmap-node-mapping',
+ 'data': { 'mapping': ['MigrationBlockNodeMapping'] } }
@@ -73,6 +73,8 @@
#include "qemu/hbitmap.h"
#include "qemu/cutils.h"
#include "qapi/error.h"
+#include "qapi/qapi-commands-migration.h"
+#include "qapi/qmp/qdict.h"
#include "trace.h"
#define CHUNK_SIZE (1 << 10)
@@ -121,6 +123,9 @@ typedef struct DirtyBitmapMigState {
bool bulk_completed;
bool no_bitmaps;
+ QDict *node_in_mapping;
+ QDict *node_out_mapping;
+
/* for send_bitmap_bits() */
BlockDriverState *prev_bs;
BdrvDirtyBitmap *prev_bitmap;
@@ -281,8 +286,13 @@ static int init_dirty_bitmap_migration(void)
dirty_bitmap_mig_state.no_bitmaps = false;
for (bs = bdrv_next_all_states(NULL); bs; bs = bdrv_next_all_states(bs)) {
+ const QDict *map = dirty_bitmap_mig_state.node_out_mapping;
const char *name = bdrv_get_device_or_node_name(bs);
+ if (map) {
+ name = qdict_get_try_str(map, name) ?: name;
+ }
+
FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
if (!bdrv_dirty_bitmap_name(bitmap)) {
continue;
@@ -600,6 +610,8 @@ static int dirty_bitmap_load_bits(QEMUFile *f, DirtyBitmapLoadState *s)
static int dirty_bitmap_load_header(QEMUFile *f, DirtyBitmapLoadState *s)
{
+ const QDict *map = dirty_bitmap_mig_state.node_in_mapping;
+ const char *mapped_node = "(none)";
Error *local_err = NULL;
bool nothing;
s->flags = qemu_get_bitmap_flags(f);
@@ -612,7 +624,13 @@ static int dirty_bitmap_load_header(QEMUFile *f, DirtyBitmapLoadState *s)
error_report("Unable to read node name string");
return -EINVAL;
}
- s->bs = bdrv_lookup_bs(s->node_name, s->node_name, &local_err);
+
+ mapped_node = s->node_name;
+ if (map) {
+ mapped_node = qdict_get_try_str(map, mapped_node) ?: mapped_node;
+ }
+
+ s->bs = bdrv_lookup_bs(mapped_node, mapped_node, &local_err);
if (!s->bs) {
error_report_err(local_err);
return -EINVAL;
@@ -634,7 +652,7 @@ static int dirty_bitmap_load_header(QEMUFile *f, DirtyBitmapLoadState *s)
if (!s->bitmap && !(s->flags & DIRTY_BITMAP_MIG_FLAG_START)) {
error_report("Error: unknown dirty bitmap "
"'%s' for block device '%s'",
- s->bitmap_name, s->node_name);
+ s->bitmap_name, mapped_node);
return -EINVAL;
}
} else if (!s->bitmap && !nothing) {
@@ -713,6 +731,44 @@ static bool dirty_bitmap_has_postcopy(void *opaque)
return true;
}
+void qmp_migrate_set_bitmap_node_mapping(MigrationBlockNodeMappingList *mapping,
+ Error **errp)
+{
+ QDict *in_mapping = qdict_new();
+ QDict *out_mapping = qdict_new();
+
+ for (; mapping; mapping = mapping->next) {
+ MigrationBlockNodeMapping *entry = mapping->value;
+
+ if (qdict_haskey(out_mapping, entry->node_name)) {
+ error_setg(errp, "Cannot map node name '%s' twice",
+ entry->node_name);
+ goto fail;
+ }
+
+ if (qdict_haskey(in_mapping, entry->alias)) {
+ error_setg(errp, "Cannot use alias '%s' twice",
+ entry->alias);
+ goto fail;
+ }
+
+ qdict_put_str(in_mapping, entry->alias, entry->node_name);
+ qdict_put_str(out_mapping, entry->node_name, entry->alias);
+ }
+
+ qobject_unref(dirty_bitmap_mig_state.node_in_mapping);
+ qobject_unref(dirty_bitmap_mig_state.node_out_mapping);
+
+ dirty_bitmap_mig_state.node_in_mapping = in_mapping;
+ dirty_bitmap_mig_state.node_out_mapping = out_mapping;
+
+ return;
+
+fail:
+ qobject_unref(in_mapping);
+ qobject_unref(out_mapping);
+}
+
static SaveVMHandlers savevm_dirty_bitmap_handlers = {
.save_setup = dirty_bitmap_save_setup,
.save_live_complete_postcopy = dirty_bitmap_save_complete,
This command allows mapping block node names to aliases for the purpose of block dirty bitmap migration. This way, management tools can use different node names on the source and destination and pass the mapping of how bitmaps are to be transferred to qemu (on the source, the destination, or even both with arbitrary aliases in the migration stream). Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Max Reitz <mreitz@redhat.com> --- Branch: https://github.com/XanClic/qemu.git migration-bitmap-mapping-rfc-v2 Branch: https://git.xanclic.moe/XanClic/qemu.git migration-bitmap-mapping-rfc-v2 (Sorry, v1 was just broken. This one should work better.) Vladimir has proposed something like this in April: https://lists.nongnu.org/archive/html/qemu-block/2020-04/msg00171.html Now I’ve been asked by my manager to look at this, so I decided to just write a patch to see how it’d play out. This is an RFC, because I’d like to tack on tests to the final version, but I’m not sure whether I can come up with something before the end of the week (and I’ll be on PTO for the next two weeks). Also, I don’t know whether migration/block-dirty-bitmap.c is the best place to put qmp_migrate_set_bitmap_mapping(), but it appears we already have some QMP handlers in migration/, so I suppose it isn’t too bad. --- qapi/migration.json | 36 ++++++++++++++++++++ migration/block-dirty-bitmap.c | 60 ++++++++++++++++++++++++++++++++-- 2 files changed, 94 insertions(+), 2 deletions(-)