[PATCH v3 1/3] migration: Make migration blocker work for snapshots too

[Peter Xu <peterx@redhat.com>]

save_snapshot() checks migration blocker, which looks sane.  At the meantime we
should also teach the blocker add helper to fail if during a snapshot, just
like for migrations.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/migration.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index bb909781b7..6f7177daa0 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2048,15 +2048,16 @@ int migrate_add_blocker(Error *reason, Error **errp)
         return -EACCES;
     }
 
-    if (migration_is_idle()) {
-        migration_blockers = g_slist_prepend(migration_blockers, reason);
-        return 0;
+    /* Snapshots are similar to migrations, so check RUN_STATE_SAVE_VM too. */
+    if (runstate_check(RUN_STATE_SAVE_VM) || !migration_is_idle()) {
+        error_propagate_prepend(errp, error_copy(reason),
+                                "disallowing migration blocker "
+                                "(migration/snapshot in progress) for: ");
+        return -EBUSY;
     }
 
-    error_propagate_prepend(errp, error_copy(reason),
-                            "disallowing migration blocker "
-                            "(migration in progress) for: ");
-    return -EBUSY;
+    migration_blockers = g_slist_prepend(migration_blockers, reason);
+    return 0;
 }
 
 void migrate_del_blocker(Error *reason)
-- 
2.31.1