[Qemu-devel] [PATCH] migration: re-active images when migration fails to complete

[zhanghailiang]

commit fe904ea8242cbae2d7e69c052c754b8f5f1ba1d6 fixed a case
which migration aborted QEMU because it didn't regain the control
of images while some errors happened.

Actually, we have another case in that error path to abort QEMU
because of the same reason:
    migration_thread()
        migration_completion()
           bdrv_inactivate_all() ----------------> inactivate images
           qemu_savevm_state_complete_precopy()
               socket_writev_buffer() --------> error because destination fails
             qemu_fflush() -------------------> set error on migration stream
           qemu_mutex_unlock_iothread() ------> unlock
    qmp_migrate_cancel() ---------------------> user cancelled migration
        migrate_set_state() ------------------> set migrate CANCELLING
    migration_completion() -----------------> go on to fail_invalidate
        if (s->state == MIGRATION_STATUS_ACTIVE) -> Jump this branch
    migration_thread() -----------------------> break migration loop
      vm_start() -----------------------------> restart guest with inactive
                                                images
We failed to regain the control of images because we only regain it
while the migration state is "active", but here users cancelled the migration
when they found some errors happened (for example, libvirtd daemon is shutdown
in destination unexpectedly).

Signed-off-by: zhanghailiang <address@hidden>
---
 migration/migration.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/migration/migration.c b/migration/migration.c
index f498ab8..0c1ee6d 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1752,7 +1752,8 @@ fail_invalidate:
     /* If not doing postcopy, vm_start() will be called: let's regain
      * control on images.
      */
-    if (s->state == MIGRATION_STATUS_ACTIVE) {
+    if (s->state == MIGRATION_STATUS_ACTIVE ||
+        s->state == MIGRATION_STATUS_CANCELLING) {
         Error *local_err = NULL;
 
         bdrv_invalidate_cache_all(&local_err);
-- 
1.8.3.1